TW202203434A - Method for forming three-dimension memory device - Google Patents

Abstract

Embodiments of a 3D memory device and a method for forming the same are disclosed. A sacrificial layer is provided, a first stop layer on the sacrificial layer, an n-type doped semiconductor layer on the first stop layer, and a dielectric stack layer on the n-type doped semiconductor layer are sequentially formed on the substrate. A plurality of channel structures each extending vertically through the dielectric stack layer and the N-type doped semiconductor layer and stopping at the first stop layer are formed. The memory stack layer is used to replace the dielectric stack layer, so that each channel structure in the plurality of channel structures vertically extends through the memory stack layer and the N-type doped semiconductor layer. The substrate is sequentially removed, the sacrificial layer and the first stop layer to expose the end of each of the plurality of channel structures. A conductive layer is formed in contact with the ends of the plurality of channel structures.

Description

Method for forming a three-dimensional memory element

Embodiments of the present disclosure relate to three-dimensional (3D) memory elements and methods of fabricating the same.

Scale planar memory cells to smaller sizes by improving process technology, circuit design, programming algorithms, and manufacturing processes. However, as memory cell feature sizes approach lower limits, planar processes and fabrication techniques become challenging and costly. As a result, the storage density for planar memory cells approaches an upper limit.

3D memory architectures can address the density limitations in planar storage cells. A 3D memory architecture includes a memory array and peripherals that control the signals stored and read from the memory array.

Disclosed herein are embodiments of 3D memory elements, and methods for forming 3D memory elements.

In some of the embodiments of the present invention, a method for forming a 3D memory element is disclosed. A sacrificial layer on the substrate, a first stop layer on the sacrificial layer, an N-type doped semiconductor layer on the first stop layer, and a dielectric stack layer on the N-type doped semiconductor layer are sequentially formed. A plurality of channel structures are formed each extending vertically through the dielectric stack layer and the N-type doped semiconductor layer, stopping at the first stop layer. The dielectric stack is replaced with a storage stack such that each of the plurality of channel structures extends vertically through the storage stack and the N-type doped semiconductor layer. The substrate, the sacrificial layer, and the first stop layer are sequentially removed to expose the ends of each of the plurality of channel structures. A conductive layer is formed in contact with the ends of the plurality of channel structures.

In another example of the present invention, a method for forming a 3D memory element is disclosed. A sacrificial layer on the substrate, a first conductive layer on the sacrificial layer, an N-type doped semiconductor layer on the first conductive layer, and a dielectric stack layer on the N-type doped semiconductor layer are sequentially formed. A plurality of channel structures are formed each extending vertically through the dielectric stack layer and the N-type doped semiconductor layer, stopping at the first conductive layer. The dielectric stack is replaced with a storage stack such that each channel structure of the plurality of channel structures extends vertically through the storage stack and the N-type doped semiconductor layer. The substrate, the sacrificial layer, and a portion of the first conductive layer are sequentially removed to expose ends of each of the plurality of channel structures. A conductive layer is formed in contact with the ends of the plurality of channel structures and the first conductive layer.

In yet another example of the present invention, a method for forming a 3D memory element is disclosed. Peripheral circuits are formed on the first substrate. A plurality of channel structures are formed each extending vertically through the storage stack layer and the N-type doped semiconductor layer over the second substrate. The first substrate and the second substrate are bonded face-to-face such that the memory stack is over the peripheral circuitry. The second substrate is removed to expose the upper end of each of the plurality of channel structures and the N-type doped semiconductor layer. A conductive layer formed on the N-type doped semiconductor layer and in contact with upper ends of the plurality of channel structures.

While specific configurations and arrangements are discussed, it should be understood that this is done for illustrative purposes only. Those skilled in the relevant art will recognize that other configurations and arrangements may be used without departing from the spirit and scope of the present disclosure. It will be apparent to those skilled in the relevant art that the present disclosure may also be used in various other applications.

It should be noted that references in the specification to "one embodiment," "an embodiment," "exemplary embodiment," "some embodiments," etc. indicate that the described embodiment may include a particular feature, structure, or characteristic , various embodiments may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Furthermore, when a particular feature, structure or characteristic is described in connection with one embodiment, whether explicitly described or not, it is within the knowledge of those skilled in the relevant art to implement such feature, structure or characteristic in connection with other embodiments.

Generally, terms can be understood, at least in part, from their contextual usage. For example, the term "one or more" as used herein may be used to describe any feature, structure or characteristic in the singular or may be used to describe a combination of features, structures or characteristics in the plural, depending at least in part on the context . Similarly, terms such as "a", "an" or "the" may likewise be understood to convey singular usage or to convey plural usage, depending at least in part on context. Additionally, the term "based on" may be understood as not necessarily intended to convey an exclusive set of factors, but may allow for the presence of additional factors not necessarily explicitly described, again depending at least in part on the context.

It should be readily understood that the meanings of "on", "over" and "over" in this summary should be construed in the broadest manner, such that "on" not only means "directly on something" but also includes the meaning of "on something" with intervening features or layers, and "over" or "over" not only means The meaning of "over something" or "over something" and can include the meaning of "over something" or "over something" with no intervening features or layers in between (ie, directly on something).

Furthermore, for ease of description, spatially relative terms such as "under", "below", "lower", "over", "upper", etc. may be used herein to describe such as The relationship of one element or feature to another element or feature is shown in the figures. In addition to the orientation depicted in the figures, spatially relative terms are intended to encompass different orientations of the device during use or steps of operation. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly as well.

As used herein, the term "substrate" refers to the material upon which subsequent layers of material are added. The substrate itself can be patterned. The material added on top of the substrate may be patterned or may remain unpatterned. Additionally, the substrate may include various semiconductor materials such as silicon, germanium, gallium arsenide, indium phosphide, and the like. Alternatively, the substrate may be made of a non-conductive material such as glass, plastic or sapphire wafer.

As used herein, the term "layer" refers to a portion of a material that includes a region having a thickness. A layer may extend over the entire underlying or overlying structure, or may have a smaller extent than the underlying or overlying structure. Furthermore, a layer may be a region of a uniform or non-uniform continuous structure having a thickness less than that of the continuous structure. For example, a layer may be located between the top and bottom surfaces of the continuous structure or between any pair of horizontal planes at the top and bottom surfaces. The layers may extend horizontally, vertically and/or along a tapered surface. The substrate may be a layer, may include one or more layers therein, and/or may have one or more layers on, over, and/or under it. Layers may include multiple layers. For example, the interconnect layer may include one or more conductor and contact layers (with interconnect lines and/or vertical interconnect via contacts formed therein) and one or more dielectric layers.

As used herein, the term "nominal" refers to the expected or target value of a characteristic or parameter set during the design phase of a product or process for a component or process operating step, and above and/or or a range of values below the expected value. The range of values can be due to slight variations in the manufacturing process or tolerances. As used herein, the term "about" indicates a given amount of value that may vary based on the particular technology node associated with the subject semiconductor element. Based on a particular technology node, the term "about" may indicate a value of a given amount that varies, eg, within 10-30% of the value (eg, ±10%, ±20%, or ±30% of the value).

As used herein, the term "three-dimensional memory element" refers to a device having vertically oriented strings of memory cell transistors (referred to herein as "memory strings", eg, NAND memory strings) on a laterally oriented substrate A semiconductor element such that the memory strings extend in a vertical direction with respect to the substrate. As used herein, the term "perpendicular/perpendicular" means nominally perpendicular to the lateral surface of the substrate.

In some three-dimensional memory devices (eg, 3D NAND memory devices), a slot structure (eg, gate line slot (GLS)) is used to provide access from the front side of the device to the source of the memory array (eg, the array common source). (ACS)) electrical connection. However, the front-side source contacts can affect the electrical performance of the 3D memory device by introducing leakage currents and parasitic capacitances between the word lines and the source contacts, even in the presence of spacers between them. The formation of spacers also complicates the manufacturing process. In addition to affecting electrical performance, gap structures often include wall polysilicon and/or metal fillers, which can introduce localized stress that can cause wafer bending or warping, thereby reducing production yield.

Furthermore, in some 3D NAND memory devices, semiconductor plugs are selectively grown to surround the sidewalls of the channel structure, eg, known as sidewall selective epitaxial growth (SEG). The formation of sidewall SEGs avoids etching of the storage film at the bottom surface of the via holes as well as the semiconductor vias (which are also Known as "SONO" punch-through), thereby increasing the process window, especially when 3D NAND memory devices are fabricated with advanced technologies (eg, having 96 or more levels with a multi-stack architecture). Sidewall SEGs are typically formed by replacing the sacrificial layer between the substrate and the stack structure with sidewall SEGs, which involves multiple deposition and etching processes through the slit openings. However, as the levels of 3D NAND memory devices continue to increase, the aspect ratio of the slit openings extending through the stack structure becomes larger, so that deposition through the slit openings and The etching process is more challenging to form sidewall SEGs using known methods and is subject to improvement.

In addition, sidewall SEG structures can be combined with backside processes to form source contacts from the backside of the substrate, thereby avoiding leakage currents and parasitic capacitances between frontside source contacts and word lines, and increasing effective device area. However, since the backside process requires thinning of the substrate, it is difficult to control the thickness uniformity at the wafer level during the thinning process, which limits the production yield of 3D NAND memory devices with sidewall SEG structures and backside processes.

According to various embodiments of the present disclosure, three-dimensional memory elements with backside source contacts are provided. By moving the source contacts from the front side to the back side, the cost of each memory cell can be reduced because the effective memory cell array area can be increased, and the spacer forming process can be omitted. Device performance can also be improved, for example, by avoiding leakage currents and parasitic capacitances between word lines and source contacts, and by reducing local stress caused by front-side slot structures (as source contacts). Sidewall SEGs (eg, semiconductor plugs) can be formed from the backside of the substrate, so no deposition or etching process is required through the openings of the stack extending at the frontside of the substrate. Therefore, the complexity and cost of the manufacturing process can be reduced, and the production yield can be improved. Furthermore, since the fabrication process of the sidewall SEG is no longer affected by the aspect ratio of the opening through the stack structure, ie, is not limited by the level of the storage stack layer, the scalability of the 3D memory device can also be improved.

Before forming the sidewall SEG, the substrate on which the storage stack is formed may be removed from the backside to expose the channel structure. Thus, the choice of substrates can be extended to, for example, dummy wafers to reduce costs. In some of these embodiments of the invention, one or more stop layers are used to automatically stop the backside thinning process, allowing the substrate to be completely removed to avoid wafer thickness uniformity control issues, and reduce the manufacturing complexity of the backside process. In some of the embodiments of the invention, the same stop layer or another stop layer is used to automatically stop the via hole etch, which allows for better control of grooving variation between different via structures and further increases the backside process Windows.

After the substrate is removed, a conductive layer may be formed from the backside to electrically connect the sources of the plurality of channel structures, thereby increasing the conductivity of the array common source (ACS) of the channel structures. In some of the embodiments of the invention, the conductive layer includes a metal silicide layer in contact with the semiconductor channel of the channel structure to reduce contact resistance, and further includes a metal layer in contact with the metal silicide layer to further reduce overall resistance . As a result, the thickness of the semiconductor layer (N-type doping or P-type doping) that is part of the ACS can be reduced without affecting the ACS conductivity.

In this summary, various 3D memory device architectures and their fabrication methods (eg, with different erase operation step mechanisms) are disclosed to suit different requirements and applications. In some of the embodiments of the present invention, the sidewall SEG is part of an N-type doped semiconductor layer to enable gate-to-drain leakage (GIDL) erasure by the stereoscopic memory device. In some of the embodiments of the present invention, the sidewall SEG is part of a P-type doped semiconductor layer to enable P-well bulk erase by a stereo memory device.

FIG. 1A shows a side view of a cross-section of an exemplary three-dimensional memory element 100 in accordance with some embodiments of this disclosure. In some of the embodiments of the present invention, the 3D memory device 100 is a bonded wafer including a first semiconductor structure 102 and a second semiconductor structure 104 stacked on the first semiconductor structure 102 . According to some embodiments, the first semiconductor structure 102 and the second semiconductor structure 104 are bonded at the bonding interface 106 therebetween. As shown in FIG. 1A , the first semiconductor structure 102 may include a substrate 101 , which may include silicon (eg, single crystal silicon (c-Si)), silicon germanium (SiGe), gallium arsenide (GaAs), germanium (Ge) , SOI or any other suitable material.

The first semiconductor structure 102 of the 3D memory device 100 may include peripheral circuits 108 on the substrate 101 . Note that the x and y axes are included in FIG. 1A to further illustrate the spatial relationship of the components in the stereoscopic memory element 100 with the substrate 101 . The substrate 101 includes two lateral surfaces (eg, top and bottom surfaces) extending laterally in the x -direction (ie, the lateral direction). As used herein, determining a feature (eg, layer or element) in the y -direction (ie, the vertical direction) relative to the substrate (eg, substrate 101 ) of a semiconductor element (eg, 3D memory element 100 ) is in the semiconductor element Another feature (eg, a layer or element) is 'on', 'over', or 'below' (when the substrate is in the lowest plane of the semiconductor element in the y -direction). The same concepts used to describe spatial relationships are applied throughout this summary.

In some of the embodiments of the present invention, the peripheral circuit 108 is configured to control and sense the stereo memory device 100 . Peripheral circuitry 108 may be any suitable digital, analog, and/or mixed-signal control and sensing circuitry for facilitating the operational steps of stereo memory device 100, including but not limited to page buffers, decoders (eg, row decoders) and column decoders), sense amplifiers, drivers (e.g. word line drivers), charge pumps, current or voltage references, or any active or passive component of the circuit (e.g. transistors, diodes, resistors or capacitor). Peripheral circuitry 108 may include transistors formed “on” substrate 101 , wherein all or part of the transistors are formed in substrate 101 (eg, below the top surface of substrate 101 ) and/or directly on substrate 101 . Isolation regions (eg, shallow trench isolation (STI)) and doped regions (eg, source and drain regions of transistors) may also be formed in the substrate 101 . According to some embodiments, the transistors are high speed and have advanced logic processes (eg, 90nm, 65nm, 45nm, 32nm, 28nm, 20nm, 16nm, 14nm, 10nm, 7nm, 5nm, 3nm, 2nm, etc.). It should be understood that, in some of these embodiments of the invention, peripheral circuits 108 may also include any other circuits compatible with advanced logic processes, including logic circuits (eg, processors and programmable logic elements (PLDs)) or memory bulk circuits (eg, static random access memory (SRAM) and dynamic RAM (DRAM)).

In some of the embodiments of the present invention, the first semiconductor structure 102 of the 3D memory device 100 further includes an interconnect layer (not shown) over the peripheral circuit 108 to transmit electrical signals to and from the peripheral circuit 108 108 transmits electrical signals. The interconnect layer may include a plurality of interconnects (also referred to herein as "contacts") including lateral interconnect lines and vertical interconnect via (VIA) contacts. As used herein, the term "interconnect" may broadly include any suitable type of interconnect, such as mid-end of line (MEOL) interconnects and back-end of line (BEOL) interconnects. The interconnect layers may also include one or more interlayer dielectric (ILD) layers (also referred to as "intermetal dielectric (IMD) layers") in which interconnect lines and VIA contacts may be formed. That is, the interconnect layer may include interconnect lines and VIA contacts in multiple interlayer dielectric layers. The interconnect lines and VIA contacts in the interconnect layer may include conductive materials including, but not limited to, tungsten (W), cobalt (Co), copper (Cu), aluminum (Al), silicide, or any combination thereof. The interlayer dielectric layers in the interconnect layers may include dielectric materials including, but not limited to, silicon oxide, silicon nitride, silicon oxynitride, low-k (low-k) dielectrics, or any combination thereof.

As shown in FIG. 1A , the first semiconductor structure 102 of the three-dimensional memory device 100 may also include a bonding layer 110 at the bonding interface 106 and above the interconnect layer and the peripheral circuit 108 . The bonding layer 110 may include a plurality of bonding contacts 111 and a dielectric that electrically isolates the bonding contacts 111 . Bonding contacts 111 may include conductive materials including, but not limited to, W, Co, Cu, Al, silicides, or any combination thereof. The remaining regions of the bonding layer 110 may be formed using dielectric materials including, but not limited to, silicon oxide, silicon nitride, silicon oxynitride, low-k dielectrics, or any combination thereof. The bonding contacts 111 and surrounding dielectrics in the bonding layer 110 can be used for hybrid bonding.

Similarly, as shown in FIG. 1A , the second semiconductor structure 104 of the three-dimensional memory device 100 may also include a bonding layer 112 at the bonding interface 106 and above the bonding layer 110 of the first semiconductor structure 102 . The bonding layer 112 may include a plurality of bonding contacts 113 and a dielectric layer that electrically isolates the bonding contacts 113 . Bonding contacts 113 may include conductive materials including, but not limited to, W, Co, Cu, Al, silicides, or any combination thereof. The remaining regions of the bonding layer 112 may be formed using dielectrics including, but not limited to, silicon oxide, silicon nitride, silicon oxynitride, low-k dielectrics, or any combination thereof. Bonding contacts 113 and surrounding dielectrics in bonding layer 112 can be used for hybrid bonding. According to some embodiments, the bonding contact 113 is in contact with the bonding contact 111 at the bonding interface 106 .

As described in detail below, the second semiconductor structure 104 may be bonded on top of the first semiconductor structure 102 in a face-to-face manner at the bonding interface 106 . In some of these embodiments of the present invention, the bonding interface 106 is disposed between the bonding layer 110 and the bonding layer 112 as a hybrid bonding (also referred to as "metal/dielectric hybrid bonding") structure , hybrid bonding is a direct bonding technique (e.g. forming a bond between surfaces without the use of an intermediate layer such as solder or adhesive) and can achieve both metal-metal bonding and dielectric-dielectric Bond. In some of these embodiments of the invention, the bonding interface 106 is the location where the bonding layer 112 and the bonding layer 110 meet and bond. In practice, the bonding interface 106 may be a layer having a specific thickness that includes the top surface of the bonding layer 110 of the first semiconductor structure 102 and the bottom surface of the bonding layer 112 of the second semiconductor structure 104 .

In some of these embodiments of the present invention, the second semiconductor structure 104 of the stereoscopic memory device 100 further includes an interconnect layer (not shown) over the bonding layer 112 to transmit electrical signals. The interconnect layer may include multiple interconnects, such as mid-line (MEOL) interconnects and back-end (BEOL) interconnects. The interconnect layer may also include one or more interlayer dielectric layers in which interconnect lines and VIA contacts may be formed. The interconnect lines and VIA contacts in the interconnect layer may include conductive materials including, but not limited to, W, Co, Cu, Al, silicide, or any combination thereof. The interlayer dielectric layers in the interconnect layers may include dielectric materials including, but not limited to, silicon oxide, silicon nitride, silicon oxynitride, low-k dielectrics, or any combination thereof.

In some of the embodiments of the present invention, the three-dimensional memory device 100 is a NAND flash memory device, wherein the storage cells are provided in the form of an array of NAND memory strings. As shown in FIG. 1A , the second semiconductor structure 104 of the three-dimensional memory device 100 may include an array of channel structures 124 serving as an array of NAND memory strings. As shown in FIG. 1A , each channel structure 124 may extend vertically through a plurality of pairs each including a conductive layer 116 and a dielectric layer 118 . The alternating conductive layers 116 and dielectric layers 118 are part of the storage stack layer 114 . The number of pairs of conductive layers 116 and dielectric layers 118 (eg, 32, 64, 96, 128, 160, 192, 224, 256 or more) in the memory stack 114 determines the number of memory cells in the three-dimensional memory element 100 quantity. It should be understood that in some of these embodiments of the present invention, the storage stack layer 114 may have a multi-stack architecture (not shown) that includes multiple memory stacks stacked on top of each other. The number of pairs of conductive layers 116 and dielectric layers 118 in each memory stack may be the same or different.

The storage stack 114 may include a plurality of interleaved conductive layers 116 and dielectric layers 118 . Conductive layers 116 and dielectric layers 118 in storage stack 114 may alternate in a vertical direction. In other words, each conductive layer 116 may be adjoined by two dielectric layers 118 on both sides, and each dielectric layer 118 may be bordered by two The conductive layer 116 is contiguous. The conductive layer 116 may include a conductive material including, but not limited to, W, Co, Cu, Al, polysilicon, doped silicon, silicide, or any combination thereof. Each conductive layer 116 may include a gate electrode (gate line) surrounded by an adhesive layer and a gate dielectric layer. The gate electrodes of conductive layer 116 may extend laterally as word lines, terminating at one or more stepped structures of storage stack layer 114 . The dielectric layer 118 may include a dielectric material including, but not limited to, silicon oxide, silicon nitride, silicon oxynitride, or any combination thereof.

As shown in FIG. 1A , the second semiconductor structure 104 of the 3D memory device 100 may further include an N-type doped semiconductor layer 120 over the storage stack layer 114 . The N-type doped semiconductor layer 120 may be an example of a "sidewall SEG" as described above. The N-type doped semiconductor layer 120 may include a semiconductor material, such as silicon. In some of the embodiments of the present invention, the N-type doped semiconductor layer 120 includes polysilicon formed by deposition techniques, as described in detail below. The N-type doped semiconductor layer 120 may be doped with any suitable N-type dopant (eg, phosphorus (P), arsenic (Ar), or antimony (Sb)), which contributes free electrons and increases the conductivity of the intrinsic semiconductor . For example, the N-type doped semiconductor layer 120 may be a polysilicon layer doped with an N-type dopant (eg, P, Ar, or Sb).

In some of these embodiments of the invention, each channel structure 124 includes a channel hole filled with a semiconductor layer (eg, as semiconductor channel 128 ) and a composite dielectric layer (eg, as storage film 126 ). In some of the embodiments of the present invention, the semiconductor channel 128 includes silicon, such as amorphous silicon, polycrystalline silicon, or monocrystalline silicon. In some of these embodiments of the invention, the storage film 126 is a composite layer including a tunneling layer, a storage layer (also referred to as a "charge trapping layer"), and a blocking layer. The remaining space of the channel structure 124 may be partially or fully filled with a capping layer and/or air gap including a dielectric material such as silicon oxide. The channel structure 124 may have a cylindrical shape (eg, a cylindrical shape). According to some embodiments, the capping layer, the semiconductor channel 128 , the tunneling layer of the storage film 126 , the storage layer, and the barrier layer are arranged radially in this order from the center of the pillar toward the outer surface. The tunneling layer may include silicon oxide, silicon oxynitride, or any combination thereof. The storage layer may include silicon nitride, silicon oxynitride, silicon, or any combination thereof. The barrier layer may include silicon oxide, silicon oxynitride, high-k dielectrics, or any combination thereof. In one example, the storage film 126 may include a composite layer of silicon oxide/silicon oxynitride/silicon oxide (ONO).

In some of these embodiments of the invention, the channel structure 124 also includes a channel plug 129 in the bottom portion (eg, at the lower end) of the channel structure 124 . As used herein, when the substrate 101 is in the lowermost plane of the three-dimensional memory element 100, the "upper end" of the component (eg, the channel structure 124 ) is the end that is further away from the substrate 101 in the y -direction, and the component (eg, the channel structure 124 ) , the "lower end" of the channel structure 124) is the end that is closer to the substrate 101 in the y -direction. The channel plug 129 may include a semiconductor material (eg, polysilicon). In some of the embodiments of the present invention, the channel plug 129 is used as the drain of the NAND memory string.

As shown in FIG. 1A , each channel structure 124 may extend vertically through the interleaved conductive layers 116 and dielectric layers 118 of the storage stack 114 into the N-type doped semiconductor layer 120 . The upper end of each channel structure 124 may be flush with or below the top surface of the N-type doped semiconductor layer 120 . That is, according to some embodiments, the channel structure 124 does not extend beyond the top surface of the N-type doped semiconductor layer 120 . In some of these embodiments of the invention, as shown in FIG. 1A , the upper end of the storage film 126 is below the upper end of the semiconductor channel 128 in the channel structure 124 . In some of these embodiments of the invention, the upper end of the storage film 126 is below the top surface of the N-type doped semiconductor layer 120 and the upper end of the semiconductor channel 128 is flush with or at the top surface of the N-type doped semiconductor layer 120 below it. For example, as shown in FIG. 1A , the storage film 126 may terminate at the bottom surface of the N-type doped semiconductor layer 120 , and the semiconductor channel 128 may extend over the bottom surface of the N-type doped semiconductor layer 120 such that the N-type doped semiconductor layer 120 is doped The semiconductor layer 120 may surround the top portion 127 of the semiconductor channel 128 extending into the N-type doped semiconductor layer 120 . In some of these embodiments of the invention, the doping concentration of the top portion 127 of the semiconductor channel 128 extending into the N-type doped semiconductor layer 120 is different from the doping concentration of the rest of the semiconductor channel 128 . For example, semiconductor channel 128 may include undoped polysilicon in addition to top portion 127, which may include doped polysilicon to increase its conductivity when making electrical connection with surrounding N-type doped semiconductor layer 120 .

In some of the embodiments of the present invention, the second semiconductor structure 104 of the three-dimensional memory device 100 includes a conductive layer 122 over and in contact with the upper end of the channel structure 124 . The conductive layer 122 can electrically connect the plurality of channel structures 124 . Although not shown in the side view of FIG. 1A , it should be understood that the conductive layer 122 may be a continuous conductive layer (eg, with holes (mesh) therein) in contact with the plurality of channel structures 124 to allow the source contacts 132 to be in plan view through the conductive plate). As a result, the conductive layer 122 and the N-type doped semiconductor layer 120 may together provide electrical connection between the sources (ie ACS) of the array of NAND memory strings in the same block. As shown in FIG. 1A , in some of these embodiments of the invention, the conductive layer 122 includes two portions in the lateral direction: a first portion on the N-type doped semiconductor layer 120 (outside the area of the channel structure 124 ) , and a second portion (within the region of the channel structure 124 ) adjacent to the N-type doped semiconductor layer 120 and in contact with the upper end of the channel structure 124 . That is, according to some embodiments, at least a portion (ie, the first portion) of the conductive layer 122 is on the N-type doped semiconductor layer 120 . According to some embodiments, the remaining portion (ie, the second portion) of the conductive layer 122 surrounding the upper end of each channel structure 124 (which extends into the N-type doped semiconductor layer 120 ) is in contact with the top portion 127 of the semiconductor channel 128 . . As described in detail below, the storage stack layer 114 and the conductive layer 122 and the top portion 127 of the semiconductor channel 128 are formed on opposite sides of the N-type doped semiconductor layer 120 , respectively, which may avoid passing through openings extending through the storage stack layer 114 . of any deposition or etch process, thereby reducing manufacturing complexity and cost and increasing yield and vertical scalability.

In some of the embodiments of the present invention, the conductive layer 122 includes multiple layers in a vertical direction, including a metal silicide layer 121 and a metal layer 123 over the metal silicide layer 121 . Each of the metal silicide layer 121 and the metal layer 123 may be a continuous film. The metal silicide layer 121 may be disposed over and in contact with the N-type doped semiconductor layer 120 (in the first portion of the conductive layer 122 ) and the upper end of the channel structure 124 (in the second portion of the conductive layer 122 ). In some of these embodiments of the invention, a portion of the metal silicide layer 121 surrounds and contacts the top portion 127 of the semiconductor channel 128 extending into the N-type doped semiconductor layer 120 for electrical connection with the plurality of channel structures 124 . The metal silicide layer 121 may comprise a metal silicide, eg, copper silicide, cobalt silicide, nickel silicide, titanium silicide, tungsten silicide, silver silicide, aluminum silicide, gold silicide, platinum silicide, any other suitable metal silicide, or its any combination. According to some embodiments, metal layer 123 is over and in contact with metal silicide layer 121 . The metal layer 123 may include a metal, eg, W, Co, Cu, Al, nickel (Ni), titanium (Ti), any other suitable metal, or any combination thereof. It should be understood that the metal in metal layer 123 may broadly include any suitable conductive metal compounds and metal alloys, such as titanium nitride and tantalum nitride. The metal silicide layer 121 may reduce the contact resistance between the conductive layer 122 and the top portion 127 of the semiconductor channel 128 , and serve as a barrier for the metal layer 123 in the conductive layer 122 .

By combining the conductive layer 122 and the N-type doped semiconductor layer 120, the gap between the channel structures 124 (ie, at the ACS of the NAND memory strings in the same block) can be increased compared to the N-type doped semiconductor layer 120 alone. ), thereby improving the electrical performance of the three-dimensional memory device 100 . By introducing conductive layer 122, in order to maintain the same conductivity/resistance between channel structures 124, the thickness of N-type doped semiconductor layer 120 may be reduced, eg, to less than about 50 nm, eg, less than 50 nm. In some of the embodiments of the present invention, the thickness of the N-type doped semiconductor layer 120 is between about 10 nm and about 30 nm, such as between 10 nm and 30 nm (eg, 10 nm, 11nm, 12nm, 13nm, 14nm, 15nm, 16nm, 17nm, 18nm, 19nm, 20nm, 21nm, 22nm, 23nm nm, 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, 30 nm, any range bounded by any of these values as a lower limit, or within in any range bounded by any two values of ). The combination of the N-type doped semiconductor layer 120 and the conductive layer 122 surrounding the top portion 127 of the semiconductor channel 128 of the channel structure 124 may enable a GIDL auxiliary body bias for the erase operation step of the 3D memory device 100 . The GIDL around the source select gate of the NAND memory string can generate hole current into the NAND memory string to increase the body potential for the erase operation step. That is, according to some embodiments, the three-dimensional memory element 100 is configured to generate a GIDL auxiliary body bias when performing the erase operation step.

As shown in FIG. 1A , the second semiconductor structure 104 of the three-dimensional memory device 100 may also include insulating structures 130 that each extend vertically through the interleaved conductive layers 116 and dielectric layers 118 of the storage stack 114 . According to some embodiments, unlike the channel structures 124 that extend further into the N-type doped semiconductor layer 120 , the insulating structures 130 stop at the bottom surface of the N-type doped semiconductor layer 120 , ie, do not extend vertically into the N-type doped semiconductor layer 120 . in the doped semiconductor layer 120 . That is, the top surface of the insulating structure 130 may be flush with the bottom surface of the N-type doped semiconductor layer 120 . Each insulating structure 130 may also extend laterally to divide the channel structure 124 into multiple pieces. That is, the storage stack layer 114 may be divided into a plurality of memory blocks by the insulating structure 130 such that the array of channel structures 124 may be divided into individual memory blocks. Unlike slot structures including front-side ACS contacts in existing 3D NAND memory devices described above, according to some embodiments, insulating structure 130 does not include any contacts therein (ie, does not function as a source contact), and thus does not introduce contact with conductive layers 116 (including word lines) parasitic capacitance and leakage current. In some of these embodiments of the present invention, each insulating structure 130 includes an opening (eg, a gap) filled with one or more dielectric materials including, but not limited to, silicon oxide, silicon nitride, silicon oxynitride, or any combination thereof. In one example, each insulating structure 130 may be filled with silicon oxide.

Furthermore, as described in detail below, because the openings used to form the insulating structures 130 are not used to form the N-type doped semiconductor layer 120 and the second portion of the conductive layer 122 , the openings follow the staggered conductive layers 116 and dielectric layers 118 . The increased aspect ratio (eg, greater than 50) with an increase in the number of , will not affect the formation of the N-type doped semiconductor layer 120 and the conductive layer 122 .

As shown in FIG. 1A , instead of the front-side source contact, the three-dimensional memory element 100 may include a backside source contact 132 over the storage stack layer 114 and in contact with the N-type doped semiconductor layer 120 . The source contact 132 and the storage stack 114 (and the insulating structure 130 therethrough) may be disposed on opposite sides of the N-type doped semiconductor layer 120 and are thus considered "backside" source contacts. In some of the embodiments of the present invention, the source contact 132 passes through the N-type doped semiconductor layer 120 and is electrically connected to the semiconductor channel 128 of the channel structure 124 . In some of these embodiments of the invention, the source contact 132 is not laterally aligned with the insulating structure 130, but is proximate the channel structure 124 to reduce the resistance of the electrical connection therebetween. For example, source contact 132 may be located laterally between insulating structure 130 and channel structure 124 (eg, in the x -direction in FIG. 1 ). Source contact 132 may comprise any suitable type of contact. In some of these embodiments of the invention, the source contact 132 includes a VIA contact. In some of these embodiments of the invention, the source contacts 132 comprise laterally extending wall contacts. The source contact 132 may include one or more conductive layers, such as a metal layer (eg, W, Co, Cu, or Al) or a silicide layer surrounded by an adhesive layer (eg, titanium nitride (TiN)).

As shown in FIG. 1A , the three-dimensional memory device 100 may also include a back end-of-line (BEOL) interconnect layer 133 over the source contact 132 and electrically connected to the source contact 132 for pad-out ), for example, to transmit electrical signals between the three-dimensional memory device 100 and an external circuit. In some of the embodiments of the present invention, the interconnect layer 133 includes one or more interlayer dielectric layers 134 on the N-type doped semiconductor layer 120 and a redistribution layer 136 on the interlayer dielectric layer 134 . According to some embodiments, the upper end of the source contact 132 is flush with the top surface of the interlayer dielectric layer 134 and the bottom surface of the redistribution layer 136, and the source contact 132 extends vertically through the interlayer dielectric layer 134 and the conductive layer 122 enters the N-type doped semiconductor layer 120 . The interlayer dielectric layer 134 in the interconnect layer 133 may include a dielectric material including, but not limited to, silicon oxide, silicon nitride, silicon oxynitride, low-k dielectrics, or any combination thereof. The redistribution layer 136 in the interconnect layer 133 may include a conductive material including, but not limited to, W, Co, Cu, Al, silicide, or any combination thereof. In one example, the redistribution layer 136 may include Al. In some of these embodiments of the present invention, the interconnect layer 133 further includes a passivation layer 138 as the outermost layer for passivation and protection of the three-dimensional memory device 100 . A portion of redistribution layer 136 may be exposed from passivation layer 138 as contact pad 140 . That is, the interconnect layer 133 of the three-dimensional memory device 100 may also include contact pads 140 for wire bonding and/or bonding with intermediate layers.

In some of the embodiments of the present invention, the second semiconductor structure 104 of the 3D memory device 100 further includes a contact 142 and a contact 144 through the N-type doped semiconductor layer 120 . According to some embodiments, since the N-type doped semiconductor layer 120 may include polysilicon, the contacts 142 and 144 are through-silicon contacts (TSCs). In some of these embodiments of the invention, contact 142 extends through N-type doped semiconductor layer 120 and interlayer dielectric layer 134 to contact redistribution layer 136 such that N-type doped semiconductor layer 120 penetrates source contact 132 and Redistribution layer 136 of interconnect layer 133 is electrically connected to contact 142 . In some of these embodiments of the present invention, the contact 144 extends through the N-type doped semiconductor layer 120 and the interlayer dielectric layer 134 to make contact with the contact pad 140 . Contacts 142 and 144 may each include one or more conductive layers, such as metal layers (eg, W, Co, Cu, or Al) or silicide layers, surrounded by an adhesion layer (eg, TiN). In some of the embodiments of the present invention, at least the contact 144 further includes a spacer (eg, a dielectric layer) to electrically isolate the contact 144 from the N-type doped semiconductor layer 120 .

In some of these embodiments of the invention, the three-dimensional memory device 100 also includes a perimeter contact 146 and a perimeter contact 148 , each extending vertically outside the storage stack layer 114 . Each peripheral contact 146 or 148 may have a depth greater than that of the storage stack layer 114 to extend vertically from the bonding layer 112 to the N-type doped semiconductor layer 120 in peripheral regions outside the storage stack layer 114 . In some of these embodiments of the invention, perimeter contact 146 is below and in contact with contact 142 such that N-type doped semiconductor layer 120 is electrically connected through at least source contact 132 , interconnect layer 133 , contact 142 and perimeter contact 146 to peripheral circuits 108 in the first semiconductor structure 102 . In some of these embodiments of the invention, the peripheral contact 148 is below and in contact with the contact 144 such that the peripheral circuit 108 in the first semiconductor structure 102 is electrically connected to the pad output through at least the contact 144 and the peripheral contact 148 Contact pad 140 . Each of perimeter contact 146 and perimeter contact 148 may include one or more conductive layers, such as a metal layer (eg, W, Co, Cu, or Al) or a silicide layer surrounded by an adhesive layer (eg, TiN). In some of these embodiments of the invention, the conductive layer 122 is within the region of the storage stack layer 114, ie, does not extend laterally into the perimeter region, such that the contacts 142 and 144 do not extend vertically through the conductive layer 122 so as to Make contact with peripheral contacts 148 and 144, respectively.

As shown in FIG. 1A , the three-dimensional memory device 100 also includes various local contacts (also referred to as “C1 ”) as part of the interconnect structure, which are in direct contact with structures in the storage stack layer 114 . In some of these embodiments of the invention, the localized contacts include channel localized contacts 150 , each of which is below and in contact with the lower end of the corresponding channel structure 124 . Each channel local contact 150 may be electrically connected to a bitline contact (not shown) for bitline fan out. In some of these embodiments of the present invention, the local contacts also include word line local contacts 152 , each of which are under and in contact with respective conductive layers 116 (including word lines) at the stepped structure of the storage stack 114 for use with Fanout on character lines. Local contacts (eg, via local contact 150 and word line local contact 152 ) may be electrically connected to peripheral circuitry 108 of first semiconductor structure 102 through at least bonding layer 112 and bonding layer 110 . The local contacts (eg, via local contact 150 and wordline local contact 152 ) may each include one or more conductive layers, such as a metal layer (eg, W, Co, Cu, or Al) surrounded by an adhesive layer (eg, TiN) ) or silicide layer.

FIG. 1B shows a side view of a cross-section of another exemplary stereoscopic memory element 155 in accordance with some embodiments of this disclosure. The 3D memory device 155 is similar to the 3D memory device 100 except for the different structures of the conductive layer 122 and the upper end of the channel structure 124 . It should be understood that, for ease of description, details of other identical structures in both stereoscopic memory elements 155 and 100 are not repeated.

As shown in FIG. 1B , according to some embodiments, each channel structure 124 further includes a channel plug 125 adjacent to the N-type doped semiconductor layer 120 . In some of these embodiments of the invention, each channel plug 125 surrounds and contacts a corresponding top portion 127 of the semiconductor channel 128 . The top surface of the channel plug 125 may be flush with the top surface of the N-type doped semiconductor layer 120 . Channel plug 125 may be of the same material (eg, doped polysilicon) as top portion 127 of semiconductor channel 128 and thus may be considered part of semiconductor channel 128 of channel structure 124 . That is, in the context of the present invention, the entire doped polysilicon structure surrounded by the N-type doped semiconductor layer 120 can be regarded as the upper end of the channel structure 124 . Thus, according to some embodiments, conductive layer 122 (and metal silicide layer 121 therein) in both 3D memory device 100 and 3D memory device 155 is in contact with the upper end of channel structure 124 .

Unlike the conductive layer 122 in the 3D memory device 100 (as shown in FIG. 1A , in the 3D memory device 100 , the second portion of the conductive layer 122 is below the top surface of the N-type doped semiconductor layer 120 and surrounds the via structure 124 ), because the upper end of the channel structure 124 also includes the channel plug 125 in FIG. 1B , the entire conductive layer 122 is above the top surface of the N-type doped semiconductor layer 120 . As shown in FIG. 1B , the top surface of the upper end of the channel structure 124 is flush with the top surface of the N-type doped semiconductor layer 120 , and the conductive layer 122 is disposed on the upper end of the N-type doped semiconductor layer 120 and the channel structure 124 . In other words, a portion of the recess filling between the N-type doped semiconductor layer 120 and the top portion 127 of the semiconductor channel 128 in the conductive layer 122 in the 3D memory device 100 may be plugged by the channel in the 3D memory device 155 125 is replaced so that the conductive layer 122 can be formed in the same plane on the top surfaces of the N-type doped semiconductor layer 120 and the channel structure 124 .

Figure 1C shows a side view of a cross-section of yet another exemplary stereoscopic memory element 160 in accordance with some embodiments of this disclosure. The 3D memory device 160 is similar to the 3D memory device 100 except for the different structure of the conductive layer 122 . It should be understood that, for ease of description, details of other identical structures in both the 3D memory cell 160 and the 3D memory cell 100 are not repeated.

As shown in FIG. 1C , according to some embodiments, metal layer 123 of conductive layer 122 is in contact with semiconductor channel 128 and a portion of metal layer 123 is over and in contact with metal silicide layer 121 . Unlike conductive layer 122 in 3D memory device 100 (in 3D memory device 100 , a portion of metal silicide layer 121 is below the top surface of N-type doped semiconductor layer 120 and surrounds top portion 127 of semiconductor channel 128 ), in the three-dimensional memory device 160 , only the metal layer 123 is below the top surface of the N-type doped semiconductor layer 120 and surrounds the top portion 127 of the semiconductor channel 128 . However, in the 3D memory device 100 , the 3D memory device 155 and the 3D memory device 160 , the first portion of the conductive layer 122 has the same structure, ie, has a metal silicide layer on the N-type doped semiconductor layer 120 121, and a metal layer 123 over and in contact with the metal silicide layer 121. As for the second portion of the conductive layer 122 (in the area of the channel structure 124 ), the various structures in the 3D memory device 100 , the 3D memory device 155 and the 3D memory device 160 can be used as described in detail below with respect to the fabrication process. Different examples of forming conductive layer 122 (eg, the manner in which the recess between N-type doped semiconductor layer 120 and top portion 127 of semiconductor channel 128 is filled) are described.

For example, as described in detail below, the metal silicide layer 121 of the three-dimensional memory device 160 in FIG. 1C may be part of a stop layer for automatically stopping the etching of the channel holes of the channel structure 124 . The stop layer may be patterned to expose the upper end of the channel structure 124 from the backside of the N-type doped semiconductor layer 120 , and the remainder of the stop layer may remain in the 3D memory device 160 as the metal silicide layer 121 . Then, a metal layer 123 may be formed to fill the recess between the N-type doped semiconductor layer 120 and the top portion 127 of the semiconductor channel 128 , and on the metal silicide layer 121 . Conversely, the same stop layer in 3D memory element 100 and 3D memory element 155 may be removed prior to forming conductive layer 122 . Therefore, after removing the stop layer from the backside of the N-type doped semiconductor layer 120, the metal silicide layer 121 in the three-dimensional memory device 100 and the three-dimensional memory device 155 can be formed to contact the upper end of the channel structure 124, wherein the The absence of the channel plug 125 in the 3D memory device 100 or the presence of the channel plug 125 in the 3D memory device 155 can reduce the contact resistance with the channel structure 124 compared to the conductive layer 122 in the 3D memory device 160 , but increases the number and time of the process.

2A shows a side view of a cross-section of yet another exemplary stereoscopic memory element 200 in accordance with some embodiments of this disclosure. In some of the embodiments of the present invention, the 3D memory device 200 is a bonded wafer including a first semiconductor structure 202 and a second semiconductor structure 204 stacked over the first semiconductor structure 202 . According to some embodiments, the first semiconductor structure 202 and the second semiconductor structure 204 are bonded at a bonding interface 206 therebetween. As shown in FIG. 2A, the first semiconductor structure 202 may include a substrate 201, which may include silicon (eg, single crystal silicon (c-Si)), SiGe, GaAs, Ge, SOI, or any other suitable material.

The first semiconductor structure 202 of the 3D memory device 200 may include peripheral circuits 208 on the substrate 201 . In some of the embodiments of the present invention, the peripheral circuit 208 is configured to control and sense the stereo memory device 200 . Peripheral circuitry 208 may be any suitable digital, analog, and/or mixed-signal control and sensing circuitry for facilitating the operational steps of stereo memory device 200, including (but not limited to) page buffers, decoders (eg, line decoders and column decoders), sense amplifiers, drivers (e.g. word line drivers), charge pumps, current or voltage references, or any active or passive component of the circuit (e.g. transistors, diodes, resistors device or capacitor). Peripheral circuitry 208 may include transistors formed “on” substrate 201 , wherein all or part of the transistors are formed in substrate 201 (eg, below the top surface of substrate 201 ) and/or directly on substrate 201 . Isolation regions (eg, shallow trench isolation (STI)) and doped regions (eg, source and drain regions of transistors) may also be formed in the substrate 201 . According to some embodiments, the transistors are high speed and have advanced logic processes (eg, 90nm, 65nm, 45nm, 32nm, 28nm, 20nm, 16nm, 14nm, 10nm, 7nm, 5nm, 3nm, 2nm, etc. technology nodes). It should be appreciated that in some of these embodiments of the invention, peripheral circuits 208 may also include any other circuits compatible with advanced logic processes, including logic circuits (eg, processors and PLDs) or memory circuits (eg, SRAM and DRAM).

In some of the embodiments of the invention, the first semiconductor structure 202 of the 3D memory device 200 further includes an interconnect layer (not shown) over the peripheral circuit 208 to transmit electrical signals to and from the peripheral circuit 208 208 transmits electrical signals. The interconnect layer may include multiple interconnects (also referred to herein as "contacts"), including lateral interconnect lines and VIA contacts. As used herein, the term "interconnect" may broadly include any suitable type of interconnect, such as mid-range (MEOL) interconnects and back-end (BEOL) interconnects. The interconnect layers may also include one or more interlayer dielectric layers (also referred to as "IMD layers") in which interconnect lines and VIA contacts may be formed. That is, the interconnect layer may include interconnect lines and VIA contacts in multiple interlayer dielectric layers. The interconnect lines and VIA contacts in the interconnect layer may include conductive materials including, but not limited to, W, Co, Cu, Al, silicide, or any combination thereof. The interlayer dielectric layers in the interconnect layers may include dielectric materials including, but not limited to, silicon oxide, silicon nitride, silicon oxynitride, low-k dielectrics, or any combination thereof.

As shown in FIG. 2A , the first semiconductor structure 202 of the three-dimensional memory device 200 may also include a bonding layer 210 at the bonding interface 206 and above the interconnect layer and the peripheral circuit 208 . The bonding layer 210 may include a plurality of bonding contacts 211 and a dielectric material that electrically isolates the bonding contacts 211 . Bonding contacts 211 may include conductive materials including, but not limited to, W, Co, Cu, Al, silicide, or any combination thereof. The remaining regions of the bonding layer 210 may be formed using dielectric materials including, but not limited to, silicon oxide, silicon nitride, silicon oxynitride, low-k dielectrics, or any combination thereof. Bonding contacts 211 and surrounding dielectrics in bonding layer 210 can be used for hybrid bonding.

Similarly, as shown in FIG. 2A , the second semiconductor structure 204 of the three-dimensional memory device 200 may also include a bonding layer 212 at the bonding interface 206 and above the bonding layer 210 of the first semiconductor structure 202 . The bonding layer 212 may include a plurality of bonding contacts 213 and a dielectric material that electrically isolates the bonding contacts 213 . Bonding contacts 213 may include conductive materials including, but not limited to, W, Co, Cu, Al, silicide, or any combination thereof. The remaining regions of the bonding layer 212 may be formed using dielectrics including, but not limited to, silicon oxide, silicon nitride, silicon oxynitride, low-k dielectrics, or any combination thereof. The bonding contacts 213 and surrounding dielectric material in the bonding layer 212 can be used for hybrid bonding. According to some embodiments, the bonding contact 213 is in contact with the bonding contact 211 at the bonding interface 206 .

As described in detail below, the second semiconductor structure 204 may be bonded on top of the first semiconductor structure 202 in a face-to-face manner at the bonding interface 206 . In some of these embodiments of the present invention, the bonding interface 206 is disposed between the bonding layer 210 and the bonding layer 212 as a hybrid bonding (also referred to as "metal/dielectric hybrid bonding") structure , hybrid bonding is a direct bonding technique (e.g. forming a bond between surfaces without the use of an intermediate layer such as solder or adhesive) and can achieve both metal-metal bonding and dielectric-dielectric Bond. In some of these embodiments of the invention, the bond interface 206 is where the bond layer 212 and the bond layer 210 meet and bond. In practice, the bonding interface 206 may be a layer having a specific thickness that includes the top surface of the bonding layer 210 of the first semiconductor structure 202 and the bottom surface of the bonding layer 212 of the second semiconductor structure 204 .

In some of these embodiments of the invention, the second semiconductor structure 204 of the three-dimensional memory device 200 further includes an interconnect layer (not shown) over the bonding layer 212 to transmit electrical signals. The interconnect layer may include multiple interconnects, such as mid-range (MEOL) interconnects and back-end (BEOL) interconnects. The interconnect layer may also include one or more interlayer dielectric layers in which interconnect lines and VIA contacts may be formed. The interconnect lines and VIA contacts in the interconnect layer may include conductive materials including, but not limited to, W, Co, Cu, Al, silicide, or any combination thereof. The interlayer dielectric layers in the interconnect layers may include dielectric materials including, but not limited to, silicon oxide, silicon nitride, silicon oxynitride, low-k dielectrics, or any combination thereof.

In some of the embodiments of the present invention, the three-dimensional memory device 200 is a NAND flash memory device, wherein the storage cells are provided in the form of an array of NAND memory strings. As shown in FIG. 2A, the second semiconductor structure 204 of the three-dimensional memory device 200 may include an array of channel structures 224 that function as an array of NAND memory strings. As shown in FIG. 2A , each channel structure 224 may extend vertically through a plurality of pairs each including a conductive layer 216 and a dielectric layer 218 . The alternating conductive layers 216 and dielectric layers 218 are part of the storage stack layer 214 . The number of pairs of conductive layers 216 and dielectric layers 218 (eg, 32, 64, 96, 128, 160, 192, 224, 256, or more) in the memory stack 214 determines the number of memory cells in the three-dimensional memory element 200 quantity. It should be understood that in some of these embodiments of the present invention, the storage stack layer 214 may have a multi-stack architecture (not shown) that includes multiple memory stacks stacked on top of each other. The number of pairs of conductive layers 216 and dielectric layers 218 in each memory stack may be the same or different.

The storage stack 214 may include a plurality of interleaved conductive layers 216 and dielectric layers 218 . Conductive layers 216 and dielectric layers 218 in storage stack 214 may alternate in a vertical direction. In other words, each conductive layer 216 may be adjoined by two dielectric layers 218 on both sides, and each dielectric layer 218 may be bordered by two dielectric layers 218 on both sides, except for the layers at the top or bottom of the storage stack layer 214 The conductive layers 216 are adjacent. The conductive layer 216 may include a conductive material including, but not limited to, W, Co, Cu, Al, polysilicon, doped silicon, silicide, or any combination thereof. Each conductive layer 216 may include a gate electrode (gate line) surrounded by an adhesive layer and a gate dielectric layer. The gate electrodes of conductive layer 216 may extend laterally as word lines, terminating at one or more stepped structures of storage stack layer 214 . The dielectric layer 218 may include a dielectric material including, but not limited to, silicon oxide, silicon nitride, silicon oxynitride, or any combination thereof.

As shown in FIG. 2A , the second semiconductor structure 204 of the 3D memory device 200 may further include a P-type doped semiconductor layer 220 over the storage stack layer 214 . The P-type doped semiconductor layer 220 may be an example of a "sidewall SEG" as described above. The P-type doped semiconductor layer 220 may include a semiconductor material, such as silicon. In some of the embodiments of the present invention, the P-type doped semiconductor layer 220 includes polysilicon formed by deposition techniques, as described in detail below. The P-type doped semiconductor layer 220 may be doped into an intrinsic semiconductor with any suitable P-type dopant (eg, boron (B), gallium (Ga), or aluminum (Al)), resulting in a process known as "electrical" hole" valence electron defect. For example, the P-type doped semiconductor layer 220 may be a polysilicon layer doped with a P-type dopant (eg, B, Ga, or Al).

In some of the embodiments of the present invention, the second semiconductor structure 204 of the 3D memory device 200 further includes an N-well 221 in the P-type doped semiconductor layer 220 . The N-well 221 may be doped with any suitable N-type dopant (eg, phosphorous (P), arsenic (Ar), or antimony (Sb)), which contributes free electrons and increases the conductivity of the intrinsic semiconductor. In some of these embodiments of the present invention, the N-well 221 is doped from the bottom surface of the P-type doped semiconductor layer 220 . It should be understood that the N-well 221 may extend vertically through the entire thickness of the P-type doped semiconductor layer 220 (ie, to the top surface of the P-type doped semiconductor layer 220 ), or may extend through the entire thickness of the P-type doped semiconductor layer 220 . Extends vertically in a portion of the thickness.

In some of these embodiments of the invention, each channel structure 224 includes a channel hole filled with a semiconductor layer (eg, as semiconductor channel 228 ) and a composite dielectric layer (eg, as storage film 226 ). In some of the embodiments of the present invention, the semiconductor channel 228 comprises silicon, such as amorphous silicon, polysilicon, or monocrystalline silicon. In some of these embodiments of the invention, the storage film 226 is a composite layer including a tunneling layer, a storage layer (also referred to as a "charge trapping layer"), and a blocking layer. The remaining space of the channel structure 224 may be partially or fully filled with a capping layer and/or an air gap including a dielectric material such as silicon oxide. The channel structure 224 may have a cylindrical shape (eg, a cylindrical shape). According to some embodiments, the capping layer, the semiconductor channel 228, the tunneling layer of the storage film 226, the storage layer, and the barrier layer are arranged in this order radially from the center of the pillar toward the outer surface. The tunneling layer may include silicon oxide, silicon oxynitride, or any combination thereof. The storage layer may include silicon nitride, silicon oxynitride, silicon, or any combination thereof. The barrier layer may include silicon oxide, silicon oxynitride, high-k dielectric, or any combination thereof. In one example, the storage film 226 may include a composite layer of silicon oxide/silicon oxynitride/silicon oxide (ONO).

In some of these embodiments of the invention, the channel structure 224 also includes a channel plug 227 in the bottom portion of the channel structure 224 (eg, at the lower end). As used herein, when the substrate 201 is in the lowermost plane of the three-dimensional memory element 200, the "upper end" of a feature (eg, channel structure 224 ) is the end that is further away from the substrate 201 in the y -direction, and the feature (eg, the channel structure 224 ) , the "lower end" of the channel structure 224) is the end that is closer to the substrate 201 in the y -direction. The channel plug 227 may include a semiconductor material (eg, polysilicon). In some of these embodiments of the present invention, the channel plug 227 is used as the drain by the NAND memory string.

As shown in FIG. 2A , each channel structure 224 may extend vertically through the interleaved conductive layers 216 and dielectric layers 218 of the storage stack 214 and into the P-type doped semiconductor layer 220 . The upper end of each channel structure 224 may be flush with or below the top surface of the P-type doped semiconductor layer 220 . That is, according to some embodiments, the channel structure 224 does not extend beyond the top surface of the P-type doped semiconductor layer 220 . In some of these embodiments of the present invention, as shown in FIG. 2A , the upper end of the storage film 226 is below the upper end of the semiconductor channel 228 in the channel structure 224 . In some of these embodiments of the invention, the upper end of the storage film 226 is below the top surface of the P-type doped semiconductor layer 220 and the upper end of the semiconductor channel 228 is flush with or at the top surface of the P-type doped semiconductor layer 220 below it. For example, as shown in FIG. 2A, the storage film 226 may terminate at the bottom surface of the P-type doped semiconductor layer 220, and the semiconductor channel 228 may extend over the bottom surface of the P-type doped semiconductor layer 220 such that the P-type doped semiconductor layer 220 is doped The semiconductor layer 220 may surround and contact a top portion 229 in the semiconductor channel 228 that extends into the P-type doped semiconductor layer 220 . In some of these embodiments of the invention, the doping concentration of the top portion 229 of the semiconductor channel 228 that extends into the P-type doped semiconductor layer 220 is different from the doping concentration of the rest of the semiconductor channel 228 . For example, semiconductor channel 228 may include undoped polysilicon in addition to top portion 229 , which may include doped polysilicon to increase its electrical connection when forming electrical connections to surrounding P-type doped semiconductor layer 220 . Conductivity.

In some of the embodiments of the present invention, the second semiconductor structure 204 of the three-dimensional memory device 200 includes a conductive layer 222 over and in contact with the upper end of the channel structure 224 . The conductive layer 222 can electrically connect the plurality of channel structures 224 . Although not shown in the side view of FIG. 2A, it should be understood that the conductive layer 222 may be a continuous conductive layer (eg, having holes (mesh) therein) in contact with the plurality of channel structures 224 to allow the source contacts 132 to be in plan view through the conductive plate). As a result, the conductive layer 222 and the P-type doped semiconductor layer 220 may together provide electrical connection between the sources (ie, ACS) of the NAND memory string arrays in the same block. As shown in FIG. 2A, in some of the embodiments of the present invention, the conductive layer 222 includes two parts in the lateral direction: a first part on the P-type doped semiconductor layer 220 (outside the area of the channel structure 224), and a second portion (in the region of the channel structure 224 ) adjacent to the P-type doped semiconductor layer 220 and in contact with the upper end of the channel structure 224 . That is, according to some embodiments, at least a portion (ie, the first portion) of the conductive layer 222 is on the P-type doped semiconductor layer 220 . According to some embodiments, the remaining portion (ie, the second portion) of the conductive layer 222 surrounding the upper end of each channel structure 224 (which extends into the P-type doped semiconductor layer 220 ) is in contact with the top portion 229 of the semiconductor channel 228 . . As described in detail below, the formation of the storage stack layer 214 as well as the conductive layer 222 and the top portion 229 of the semiconductor channel 228, respectively, occurs on opposite sides of the P-type doped semiconductor layer 220, which can be done without extending through the storage stack layer. 214 of the openings, thereby reducing manufacturing complexity and cost and increasing yield and vertical scalability.

In some of the embodiments of the invention, the conductive layer 222 includes multiple layers in a vertical direction, including a metal silicide layer 219 and a metal layer 223 over the metal silicide layer 219 . Each of the metal silicide layer 219 and the metal layer 223 may be a continuous film. The metal silicide layer 219 may be disposed over and in contact with the P-type doped semiconductor layer 220 (in the first portion of the conductive layer 222 ) and the upper end of the channel structure 224 (in the second portion of the conductive layer 222 ). In some of these embodiments of the invention, a portion of the metal silicide layer 219 surrounds and contacts the top portion 229 of the semiconductor channel 228 extending into the P-type doped semiconductor layer 220 for electrical connection with the plurality of channel structures 224 . The metal silicide layer 219 may comprise a metal silicide such as copper silicide, cobalt silicide, nickel silicide, titanium silicide, tungsten silicide, silver silicide, aluminum silicide, gold silicide, platinum silicide, any other suitable metal silicide, or any combination. According to some embodiments, metal layer 223 is over and in contact with metal silicide layer 219 . Metal layer 223 may include a metal such as W, Co, Cu, Al, Ni, Ti, any other suitable metal, or any combination thereof. It should be understood that the metal in metal layer 223 may broadly include any suitable conductive metal compounds and metal alloys, such as titanium nitride and tantalum nitride. The metal silicide layer 219 can reduce the contact resistance between the conductive layer 222 and the top portion 229 of the semiconductor channel 228 and act as a barrier for the metal layer 223 in the conductive layer 222 .

By combining conductive layer 222 and P-type doped semiconductor layer 220, it is possible to increase between channel structures 224 (ie, at the ACS of NAND memory strings in the same block) compared to P-type doped semiconductor layer 220 alone ), thereby improving the electrical performance of the three-dimensional memory device 200 . By introducing conductive layer 222, in order to maintain the same conductivity/resistance between channel structures 224, the thickness of P-type doped semiconductor layer 220 can be reduced, eg, to less than about 50 nm, eg, less than 50 nm. In some of the embodiments of the present invention, the thickness of the P-type doped semiconductor layer 220 is between about 10 nm and about 30 nm, such as between 10 nm and 30 nm (eg, 10 nm, 11nm, 12nm, 13nm, 14nm, 15nm, 16nm, 17nm, 18nm, 19nm, 20nm, 21nm, 22nm, 23nm nm, 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, 30 nm, any range bounded by the lower limit of any of these values, or in any range bounded by any two values in ). P-type doped semiconductor layer 220 in combination with conductive layer 222 surrounding top portion 229 of semiconductor channel 228 of channel structure 224 may implement a P-well bulk erase operation step for 3D memory device 200 . The design of the 3D memory device 200 disclosed herein can realize the separation of the hole current path and the electron current path for forming the erase operation step and the read operation step, respectively. In some of these embodiments of the present invention, the three-dimensional memory device 200 is configured to form an electron current path between the electron source (eg, the N-well 221 ) and the semiconductor channel 228 of the channel structure 224 to Provides electrons to the NAND memory string when performing the read operation step. Instead, according to some embodiments, the 3D memory device 200 is configured to form a hole current path between a hole source (eg, the P-type doped semiconductor layer 220 ) and the semiconductor channel 228 of the channel structure 224 to perform P Holes are provided to the NAND memory strings during the bulk erase operation step.

As shown in FIG. 2A , the second semiconductor structure 204 of the three-dimensional memory device 200 may also include insulating structures 230 that each extend vertically through the interleaved conductive layers 216 and dielectric layers 218 of the storage stack layer 214 . According to some embodiments, unlike the channel structures 224 that extend further into the P-type doped semiconductor layer 220 , the insulating structures 230 stop at the bottom surface of the P-type doped semiconductor layer 220 , ie, do not extend vertically into the P-type doped semiconductor layer 220 . in the hetero semiconductor layer 220 . That is, the top surface of the insulating structure 230 may be flush with the bottom surface of the P-type doped semiconductor layer 220 . Each insulating structure 230 may also extend laterally to divide the channel structure 224 into multiple pieces. That is, the storage stack layer 214 may be divided into a plurality of memory blocks by the insulating structure 230 such that the array of channel structures 224 may be divided into individual memory blocks. Unlike slot structures including front-side ACS contacts in existing 3D NAND memory elements described above, according to some embodiments, insulating structure 230 does not include any contacts therein (ie, does not function as a source contact), and thus does not introduce contact with conductive layers 216 (including word lines) parasitic capacitance and leakage current. In some of the embodiments of the present invention, each insulating structure 230 includes an opening (eg, a gap) filled with one or more dielectric materials including, but not limited to, silicon oxide, silicon nitride, silicon oxynitride, or the like. any combination. In one example, each insulating structure 230 may be filled with silicon oxide.

Furthermore, as described in detail below, because the openings used to form the insulating structures 230 are not used to form the P-type doped semiconductor layer 220, the openings increase with the number of interleaved conductive layers 216 and dielectric layers 218. The width ratio (eg, greater than 50) will not affect the formation of the P-type doped semiconductor layer 220 and the conductive layer 222 .

As shown in FIG. 2A , instead of the front-side source contact, the three-dimensional memory element 200 may include back-side source contact 231 and source over the storage stack layer 214 and in contact with the N-well 221 and the P-type doped semiconductor layer 220 , respectively Contact 232. The source contact 231 and source contact 232 and the storage stack layer 214 (and insulating structure 230 therethrough) may be disposed on opposite sides of the P-type doped semiconductor layer 220 and are therefore considered "backside" source contacts . In some of the embodiments of the present invention, the source contact 232 in contact with the P-type doped semiconductor layer 220 is electrically connected to the semiconductor channel 228 of the channel structure 224 through the P-type doped semiconductor layer 220 . In some of the embodiments of the present invention, the source contact 231 in contact with the N-well 221 is electrically connected to the semiconductor channel 228 of the channel structure 224 through the P-type doped semiconductor layer 220 . In some of these embodiments of the invention, the source contact 232 is not aligned laterally with the insulating structure 230, but is proximate the channel structure 224 to reduce the resistance of the electrical connection therebetween. It should be understood that although the source contact 231 is laterally aligned with the insulating structure 230 as shown in FIG. 2A, in some examples the source contact 231 may not be laterally aligned with the insulating structure 230, but proximate the channel Structure 224 (eg, laterally located between insulating structure 230 and channel structure 224) to also reduce the resistance of the electrical connection therebetween. As described above, source contact 231 and source contact 232 may be used to independently control electron current and hole current during read operation steps and erase operation steps, respectively. Source contact 231 and source contact 232 may comprise any suitable type of contact. In some of these embodiments of the invention, source contact 231 and source contact 232 comprise VIA contacts. In some of these embodiments of the invention, source contact 231 and source contact 232 comprise laterally extending wall contacts. Source contact 231 and source contact 232 may include one or more conductive layers, such as a metal layer (eg, W, Co, Cu, or Al) or a silicide layer surrounded by an adhesive layer (eg, TiN).

As shown in FIG. 2A , the three-dimensional memory device 200 may also include a back end of line (BEOL) interconnect layer 233 over and electrically connected to the source contact 231 and the source contact 232 and electrically connected to the source contact 231 and the source contact 232 For pad output, for example, to transfer electrical signals between the stereo memory element 200 and external circuits. In some of these embodiments of the present invention, the interconnect layer 233 includes one or more interlayer dielectric layers 234 on the P-type doped semiconductor layer 220 and a redistribution layer 236 on the interlayer dielectric layer 234 . The upper end of the source contact 231 or the source contact 232 is flush with the top surface of the interlayer dielectric layer 234 and the bottom surface of the redistribution layer 236 . The source contact 231 and the source contact 232 can be electrically isolated by the interlayer dielectric layer 234 . In some of these embodiments of the invention, the source contact 232 extends vertically through the interlayer dielectric layer 234 and the conductive layer 222 into the P-type doped semiconductor layer 220 to electrically conduct electricity with the P-type doped semiconductor layer 220 sexual connection. In some of these embodiments of the present invention, the source contact 231 extends vertically through the interlayer dielectric layer 234 , the conductive layer 222 and the P-type doped semiconductor layer 220 into the N-well 221 for electrical communication with the N-well 221 connect. The source contact 231 may include spacers (eg, a dielectric layer) around its sidewalls to be electrically isolated from the P-type doped semiconductor layer 220 . Redistribution layer 236 may include two electrically isolated interconnects: a first interconnect 236-1 in contact with source contact 232 and a second interconnect 236-2 in contact with source contact 231.

The interlayer dielectric layer 234 in the interconnect layer 233 may include a dielectric material including, but not limited to, silicon oxide, silicon nitride, silicon oxynitride, low-k dielectrics, or any combination thereof. The redistribution layer 236 in the interconnect layer 233 may include a conductive material including, but not limited to, W, Co, Cu, Al, silicide, or any combination thereof. In one example, the redistribution layer 236 includes Al. In some of these embodiments of the present invention, the interconnect layer 233 also includes a passivation layer 238 as the outermost layer for passivation and protection of the three-dimensional memory device 200 . A portion of redistribution layer 236 may be exposed from passivation layer 238 as contact pad 240 . That is, the interconnect layer 233 of the three-dimensional memory device 200 may also include contact pads 240 for wire bonding and/or bonding with intermediate layers.

In some of the embodiments of the present invention, the second semiconductor structure 204 of the 3D memory device 200 further includes a contact 242 , a contact 243 and a contact 244 passing through the P-type doped semiconductor layer 220 . According to some embodiments, since the P-type doped semiconductor layer 220 may include polysilicon, the contacts 242, 243, and 244 are TSCs. In some of these embodiments of the invention, the contact 242 extends through the P-type doped semiconductor layer 220 and the interlayer dielectric layer 234 to contact the first interconnect 236-1 of the redistribution layer 236 such that the P-type doped semiconductor layer Layer 220 is electrically connected to contact 242 through source contact 232 and first interconnect 236 - 1 of interconnect layer 233 . In some of these embodiments of the invention, the contact 243 extends through the P-type doped semiconductor layer 220 and the interlayer dielectric layer 234 to contact the second interconnect 236-2 of the redistribution layer 236 so that the N-well 221 is transparent to the source The pole contact 231 and the second interconnection 236 - 2 of the interconnection layer 233 are electrically connected to the contact 243 . In some of these embodiments of the invention, the contact 244 extends through the P-type doped semiconductor layer 220 and the interlayer dielectric layer 234 to make contact with the contact pad 240 . Contact 242, contact 243, and contact 244 may each include one or more conductive layers, such as a metal layer (eg, W, Co, Cu, or Al) or a silicide layer surrounded by an adhesive layer (eg, TiN). In some of these embodiments of the invention, at least contact 243 and contact 244 each further include a spacer (eg, a dielectric layer) to electrically isolate contact 243 and contact 244 from P-type doped semiconductor layer 220 .

In some of these embodiments of the invention, the three-dimensional memory element 200 also includes a peripheral contact 246 , a peripheral contact 247 , and a peripheral contact 248 , each extending vertically outside the storage stack layer 214 . Each perimeter contact 246 , perimeter contact 247 or perimeter contact 248 may have a greater depth than that of the storage stack layer 214 to extend vertically from the bonding layer 212 to the P-type in a peripheral region outside the storage stack layer 214 The semiconductor layer 220 is doped. In some of these embodiments of the invention, the perimeter contact 246 is below and in contact with the contact 242 such that the P-type doped semiconductor layer 220 penetrates at least through the source contact 232, the first interconnect 236-1 of the interconnect layer 233, the contact 242 and peripheral contacts 246 are electrically connected to peripheral circuitry 208 in the first semiconductor structure 202 . In some of these embodiments of the invention, perimeter contact 247 is below and in contact with contact 243, such that N-well 221 penetrates at least source contact 231, second interconnect 236-2 of interconnect layer 233, contact 243, and the perimeter contact 247 is electrically connected to the peripheral circuit 208 in the first semiconductor structure 202 . That is to say, the electron current and hole current used for the read operation step and the erase operation step can be controlled by the peripheral circuit 208 through different electrical connections, respectively. In some of these embodiments of the invention, peripheral contact 248 is below and in contact with contact 244 such that peripheral circuitry 208 in first semiconductor structure 202 is electrically connected to pad output through at least contact 244 and peripheral contact 248 contact pad 240. Perimeter contact 246, perimeter contact 247, and perimeter contact 248 may each include one or more conductive layers, such as metal layers (eg, W, Co, Cu, or Al) or silicide layers, surrounded by an adhesive layer (eg, TiN). In some of these embodiments of the invention, conductive layer 222 is within the region of storage stack layer 214, ie, does not extend laterally into the perimeter region, such that contacts 242, 244, and 243 do not extend vertically through the conductive layer 222 to make contact with peripheral contact 246, contact 248, and contact 247, respectively.

As shown in FIG. 2A , the three-dimensional memory element 200 also includes various local contacts (also referred to as “C1 ”) as part of the interconnect structure, which are in direct contact with structures in the storage stack layer 214 . In some of these embodiments of the invention, the localized contacts include channel localized contacts 250 , each of which is below and in contact with the lower end of the corresponding channel structure 224 . Each channel local contact 250 may be electrically connected to a bitline contact (not shown) for bitline fan-out. In some of these embodiments of the invention, the local contacts also include word line local contacts 252 , each of which are under and in contact with corresponding conductive layers 216 (including word lines) at the stepped structure of the storage stack 214 for use with Fanout on character lines. Local contacts (eg, channel local contact 250 and word line local contact 252 ) may be electrically connected to peripheral circuitry 208 of first semiconductor structure 202 through at least bonding layer 212 and bonding layer 220 . The local contacts (eg, channel local contact 250 and wordline local contact 252 ) may each include one or more conductive layers, such as a metal layer (eg, W, Co, Cu, or Al) surrounded by an adhesive layer (eg, TiN) ) or silicide layer.

2B illustrates a side view of a cross-section of yet another exemplary stereoscopic memory element 255 in accordance with some embodiments of this disclosure. The 3D memory device 255 is similar to the 3D memory device 200 , except for the different structures of the conductive layer 222 and the upper end of the channel structure 224 . It should be understood that, for ease of description, details of other identical structures in both the three-dimensional memory element 255 and the three-dimensional memory element 200 are not repeated.

As shown in FIG. 2B , according to some embodiments, each channel structure 224 further includes a channel plug 225 adjacent to the P-type doped semiconductor layer 220 . In some of these embodiments of the invention, each channel plug 225 surrounds and contacts a corresponding top portion 229 of the semiconductor channel 228 . The top surface of the channel plug 225 may be flush with the top surface of the P-type doped semiconductor layer 220 . Channel plug 225 may be of the same material (eg, doped polysilicon) as top portion 229 of semiconductor channel 228 and thus may be considered part of semiconductor channel 228 of channel structure 224 . That is to say, in the context of the present invention, the entire doped polysilicon structure surrounded by the P-type doped semiconductor layer 220 can be regarded as the upper end of the channel structure 224 . Thus, according to some embodiments, conductive layer 222 (and metal silicide layer 219 therein) in both 3D memory device 200 and 3D memory device 255 is in contact with the upper end of channel structure 224 .

Unlike the conductive layer 222 in the 3D memory device 200 (as shown in FIG. 2A , in the 3D memory device 200 a second portion of the conductive layer 222 is below the top surface of the P-type doped semiconductor layer 220 and surrounds the via structure 224 ), because the upper end of the channel structure 224 also includes the channel plug 225 in FIG. 2B , the entire conductive layer 222 is above the top surface of the P-type doped semiconductor layer 220 . As shown in FIG. 2B , the top surface of the upper end of the channel structure 224 is flush with the top surface of the P-type doped semiconductor layer 220 , and the conductive layer 222 is disposed over the P-type doped semiconductor layer 220 and the upper end of the channel structure 224 . In other words, a portion of the concave portion of the conductive layer 222 in the 3D memory element 200 that fills the recess between the P-type doped semiconductor layer 220 and the top portion 229 of the semiconductor channel 228 can be replaced by the channel in the 3D memory element 255 Plugs 225 are replaced so that conductive layer 222 can be formed in the same plane on the top surfaces of P-type doped semiconductor layer 220 and channel structure 224 .

2C illustrates a side view of a cross-section of yet another exemplary stereoscopic memory element 260 in accordance with some embodiments of this disclosure. The 3D memory device 260 is similar to the 3D memory device 200 , except for the different structure of the conductive layer 222 . It should be understood that, for ease of description, details of other identical structures in both the stereo memory element 260 and the stereo memory 200 are not repeated.

As shown in FIG. 2C , according to some embodiments, metal layer 223 of conductive layer 222 is in contact with semiconductor channel 228 and a portion of metal layer 223 is over and in contact with metal silicide layer 219 . Unlike conductive layer 222 in 3D memory device 200 (in 3D memory device 200 , a portion of metal silicide layer 219 is below the top surface of P-type doped semiconductor layer 220 and surrounds the top portion 229 of semiconductor channel 228 ), in the three-dimensional memory element 260 , only the metal layer 223 is below the top surface of the P-type doped semiconductor layer 220 and surrounds the top portion 229 of the semiconductor channel 228 . However, in the 3D memory device 200 , the 3D memory device 255 and the 3D memory device 260 , the first portion of the conductive layer 222 has the same structure, ie, has a metal silicide layer on the P-type doped semiconductor layer 220 219, and a metal layer 223 over and in contact with the metal silicide layer 219. As for the second portion of the conductive layer 222 (in the area of the channel structure 224), the various structures in the 3D memory device 200, the 3D memory device 255, and the 3D memory device 260 may be described in detail below with respect to the manufacturing process Different examples for forming the conductive layer 222 are formed, for example, in the manner of how to fill the recess between the P-type doped semiconductor layer 220 and the top portion 227 of the semiconductor channel 228 .

For example, as described in detail below, the metal silicide layer 219 of the three-dimensional memory device 260 in FIG. 2C may be part of a stop layer for automatically stopping the etching of the channel holes of the channel structure 224 . The stop layer can be patterned to expose the upper end of the channel structure 224 from the backside of the P-type doped semiconductor layer 220 , and the remainder of the stop layer can remain in the three-dimensional memory element 260 as the metal silicide layer 219 . Then, a metal layer 223 may be formed to fill the recess between the P-type doped semiconductor layer 220 and the top portion 229 of the semiconductor channel 228 , and on the metal silicide layer 219 . In contrast, the same stop layer in 3D memory element 200 and 3D memory element 255 may be removed prior to forming conductive layer 222 . Therefore, after removing the stop layer from the backside of the P-type doped semiconductor layer 220, the metal silicide layer 219 in the three-dimensional memory element 200 and the three-dimensional memory element 255 can be formed to contact the upper end of the channel structure 224, wherein the There is no channel plug 225 in the 3D memory device 200, but the channel plug 225 is included in the 3D memory device 255, which can reduce the contact with the channel structure 224 compared to the conductive layer 222 in the 3D memory device 260. resistance, but increases the number of processes.

3A-3P illustrate a manufacturing process for forming an exemplary three-dimensional memory element in accordance with some embodiments of this disclosure. FIG. 5A shows a flowchart of a method 500 for forming an exemplary three-dimensional memory element in accordance with some embodiments of this disclosure. FIG. 5B shows a flowchart of another method 501 for forming an exemplary three-dimensional memory element in accordance with some embodiments of this disclosure. Examples of stereoscopic memory elements depicted in Figures 3A-3P, 5A, and 5B include stereoscopic memory element 100, stereoscopic memory element 155, and stereoscopic memory element 160 depicted in Figures 1A-1C. 3A-3P, 5A and 5B will be described together. It should be understood that the operational steps shown in method 500 and method 501 are not exclusive, and other operational steps may also be performed before, after, or between any of the operational steps shown. Furthermore, some of these operational steps may be performed concurrently or in a sequence different from that shown in Figures 5A and 5B.

Referring to Figure 5A, method 500 begins with operation 502 in which peripheral circuitry is formed on a first substrate. The first substrate may be a silicon substrate. As shown in FIG. 3G, multiple transistors are formed on the silicon substrate 350 using multiple processes including, but not limited to, lithography, etching, thin film deposition, thermal growth, implantation, chemical mechanical polishing (CMP), and any other suitable process. In some of these embodiments of the invention, doped regions (not shown) are formed in the silicon substrate 350 by ion implantation and/or thermal diffusion, which serve, for example, as source and/or drain regions of a transistor. In some of these embodiments of the present invention, isolation regions (eg, shallow trench isolation (STI)) are also formed in the silicon substrate 350 by wet and/or dry etching and thin film deposition. The transistors may be formed on the silicon substrate 350 for peripheral circuits 352 .

As shown in FIG. 3G , a bonding layer 348 is formed over the peripheral circuit 352 . Bonding layer 348 includes bonding contacts that are electrically connected to peripheral circuitry 352 . To form bonding layer 348, an interlayer dielectric layer is deposited using one or more thin film deposition processes, eg, chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), or any combination thereof; Use wet and/or dry etching (eg, reactive ion etching (RIE)) followed by one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof) to form bonding contacts through the interlayer dielectric layers.

Channel structures each extending vertically through the storage stack layer and the N-type doped semiconductor layer may be formed over the second substrate. As shown in FIG. 5A, the method 500 proceeds to operation step 504, in which a sacrificial layer on the second substrate, a first stop layer on the sacrificial layer, and an N-type on the first stop layer are sequentially formed A doped semiconductor layer, and a dielectric stack on the N-type doped semiconductor layer. A sacrificial layer may be formed on the front surface of the second substrate on which the semiconductor element may be formed. The second substrate may be a silicon substrate. It will be appreciated that since the second substrate will be removed from the final product, the second substrate may be part of a dummy wafer, eg, a carrier substrate, made of any suitable material (eg, glass, sapphire, plastic, silicon) to reduce the cost of the second substrate. In some of the embodiments of the present invention, the substrate is a carrier substrate, the N-type doped semiconductor layer includes polysilicon, and the dielectric stack layer includes alternating stacked dielectric layers and stacked sacrificial layers. In some of the embodiments of the present invention, stacked dielectric layers and stacked sacrificial layers are alternately deposited on the N-type doped semiconductor layers to form a dielectric stack. In some of the embodiments of the invention, the sacrificial layer includes two pad oxide layers (also referred to as buffer layers) and a second stop layer sandwiched between the two pad oxide layers. In some of these embodiments of the invention, the first stop layer includes a high-k dielectric layer, the second stop layer includes silicon nitride, and each of the two pad oxide layers includes silicon oxide.

As shown in FIG. 3A , a sacrificial layer 303 is formed on the carrier substrate 302 , a stopper layer 305 is formed on the sacrificial layer 303 , and an N-type doped semiconductor layer 306 is formed on the stopper layer 305 . The N-type doped semiconductor layer 306 may include polysilicon doped with an N-type dopant (eg, P, As, or Sb). The sacrificial layer 303 may comprise any suitable sacrificial material, which may then be selectively removed, and the sacrificial layer 303 may comprise a different material than the N-type doped semiconductor layer 306 . In some of these embodiments of the invention, the sacrificial layer 303 is a composite dielectric layer with a stop layer 304 sandwiched between two pad oxide layers. As described in detail below, stop layer 304 may act as a chemical mechanical polishing (CMP)/etch stop layer when carrier substrate 302 is removed from the backside, and stop layer 304 may comprise any suitable material other than that of carrier substrate 302, such as silicon nitride. Similarly, stop layer 305 may act as an etch stop layer when channel holes are etched from the front side, and stop layer 305 may include a high relative to polysilicon (the material of N-type doped semiconductor layer 306 on stop layer 305 ) Any suitable material with an etch selectivity (eg, greater than about 5). In one example, stop layer 305 may be removed from the final product later in the process, and may include a high-k dielectric layer such as aluminum oxide, hafnium oxide, zirconium oxide, or titanium oxide, to name a few. In another example, at least a portion of stop layer 305 may remain in the final product and may include metal silicides, such as copper silicide, cobalt silicide, nickel silicide, titanium silicide, tungsten silicide, silver silicide, to name a few , aluminum silicide, gold silicide, platinum silicide. It should be understood that, in some examples, a pad oxide layer (eg, a silicon oxide layer) may be formed between the carrier substrate 302 and the stop layer 304 and between the stop layer 304 and the stop layer 305 to relax between the different layers stress and avoid peeling.

According to some embodiments, to form the sacrificial layer 303, silicon oxide, silicon nitride, and silicon oxide are sequentially deposited on the carrier substrate 302 using one or more thin film deposition processes including, but not limited to, chemical vapor deposition (CVD), Physical Vapor Deposition (PVD), Atomic Layer Deposition (ALD) or any combination thereof. According to some embodiments, to form stop layer 305, a high-k dielectric layer is deposited on sacrificial layer 303 using one or more thin film deposition processes including, but not limited to, chemical vapor deposition (CVD), physical vapor deposition ( PVD), Atomic Layer Deposition (ALD), or any combination thereof. In some of these embodiments of the present invention, to form the N-type doped semiconductor layer 306, one or more thin film deposition processes (including but not limited to chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic Layer Deposition (ALD) or any combination thereof) deposits polysilicon on stop layer 305, and then uses ion implantation and/or thermal diffusion to dope the deposited polysilicon with N-type dopants (eg, P, As, or Sb). In some of these embodiments of the invention, in order to form the N-type doped semiconductor layer 306, when polysilicon is deposited on the stop layer 305, in-situ doping of an N-type dopant such as P, As, or Sb is performed miscellaneous. In some embodiments in which stop layer 305 includes a metal silicide, a metal layer is deposited on sacrificial layer 303, followed by polysilicon to form N-type doped semiconductor layer 306 on the metal layer. Then, a silicidation process may be performed on the polysilicon and metal layers by thermal processing (eg, annealing, sintering, or any other suitable process) to convert the metal layer into a metal silicide layer as stop layer 305 .

As shown in FIG. 3B , a first dielectric layer (referred to herein as a “stacked sacrificial layer” 312 ) and a second dielectric layer (referred to herein as a “stacked sacrificial layer”) and a second dielectric layer (referred to herein as A "stacked dielectric layer" 310, collectively referred to herein as a "dielectric layer pair") of the dielectric stack 308. According to some embodiments, the dielectric stack layer 308 includes a stacked sacrificial layer 312 and a stacked dielectric layer 310 that are interleaved. Stacked dielectric layers 310 and stacked sacrificial layers 312 may be alternately deposited on N-type doped semiconductor layer 306 over carrier substrate 302 to form dielectric stack layer 308 . In some of these embodiments of the present invention, each stacked dielectric layer 310 includes a silicon oxide layer, and each stacked sacrificial layer 312 includes a silicon nitride layer. The dielectric stack layer 308 may be formed by one or more thin film deposition processes including, but not limited to, chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), or any combination thereof. As shown in FIG. 3B , a stepped structure may be formed on the edge of the dielectric stack layer 308 . The stepped structure may be formed by performing a number of so-called "trimming-etch" loops on the dielectric layer pairs of the dielectric stack layer 308 towards the carrier substrate 302 . Dielectric stack 308 may have one or more sloping edges and a top dielectric layer that is shorter than the bottom dielectric layer pair due to repeated trim-etch cycles of the dielectric layer pairs applied to dielectric stack layer 308 Yes, as shown in Figure 3B.

As shown in FIG. 5A, the method 500 proceeds to operation 506 in which a plurality of channels are formed each extending vertically through the dielectric stack layer and the N-type doped semiconductor layer, stopping at a first stop layer structure. In some of the embodiments of the present invention, to form the channel structure, channel holes, each extending vertically through the dielectric stack layer and the N-type doped semiconductor layer, stopping at the first stop layer, are etched, and along each channel The sidewalls of the holes are sequentially deposited with a storage film and a semiconductor channel.

As shown in FIG. 3B , each via hole is an opening that extends vertically through the dielectric stack layer 308 and the N-type doped semiconductor layer 306 , stopping at the stop layer 305 . In some of these embodiments of the invention, a plurality of openings are formed such that each opening becomes a location for growing individual channel structures 314 in a subsequent process. In some of the embodiments of the present invention, the fabrication process for forming the via hole of the via structure 314 includes wet etching and/or dry etching, such as deep RIE (DRIE). According to some embodiments, due to the etch selectivity between the material of the stop layer 305 (eg, aluminum oxide or metal silicide) and the material of the N-type doped semiconductor layer 306 (ie, polysilicon), the etching of the channel holes Continue until stopped by a stop layer 305 (eg, a high-k dielectric layer (eg, an aluminum oxide layer) or a metal silicide layer). In some of these embodiments of the invention, etching conditions (eg, etch rate and time) can be controlled to ensure that each via hole has reached and stopped by stop layer 305, thereby separating the via hole and the channel structure 314 formed therein. Slotting variation between slots is minimized. It should be understood that, depending on the particular etch selectivity, one or more via holes may extend into stop layer 305 to a small extent, which is still considered to be stopped by stop layer 305 in the context of this disclosure.

As shown in FIG. 3B, the storage film including the barrier layer 317, the storage layer 316 and the tunneling layer 315, and the semiconductor channel 318 are sequentially formed in this order along the sidewall and bottom surface of the channel hole. In some of these embodiments of the invention, one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof), the barrier layer 317, the storage layer 316, and the tunneling layer 315 are deposited in this order along the sidewalls and bottom surface of the via hole to form a storage film. Then, by using one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof), A semiconductor material such as polysilicon (eg, undoped polysilicon) is deposited over the tunnel layer 315 to form the semiconductor channel 318 . In some of the embodiments of the present invention, a first silicon oxide layer, a silicon nitride layer, a second silicon oxide layer and a polysilicon layer (“SONO” structure) are sequentially deposited to form the barrier layer 317 and the storage layer 316 of the storage film and tunneling layer 315 and semiconductor channel 318 .

As shown in FIG. 3B, a capping layer is formed in the via hole and over semiconductor channel 318 to fully or partially fill the via hole (eg, without or with air gaps). The dielectric may be deposited using one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof) material (eg, silicon oxide), which in turn forms the capping layer. Then, a channel plug can be formed in the top portion of the channel hole. In some of these embodiments of the invention, the storage film, semiconductor channel 318 and capping layer on top of the dielectric stack layer 308 are removed and planarized by chemical mechanical polishing (CMP), wet etching and/or dry etching part of the surface. A recess may then be formed in the top portion of the via hole by wet etching and/or dry etching a portion of the semiconductor via 318 and the capping layer in the top portion of the via hole. A semiconductor material such as polysilicon may then be deposited by way of one or more thin film deposition processes (eg, chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), or any combination thereof) into the recess to form a channel plug. According to some embodiments, a channel structure 314 is thus formed through the dielectric stack layer 308 and the N-type doped semiconductor layer 306 , stopping at the stop layer 305 .

As shown in FIG. 5A, method 500 proceeds to operation 508, in which the dielectric stack is replaced with a storage stack such that the channel structure extends vertically through the storage, eg, using a so-called "gate replacement" process. Stacked layers and N-type doped semiconductor layers. In some of these embodiments of the invention, to replace the dielectric stack with the storage stack, an opening extending vertically through the dielectric stack, stopping at the N-type doped semiconductor layer is etched, and through the opening, using The stacked conductive layer replaces the stacked sacrificial layer to form a storage stack including alternating stacked dielectric layers and stacked conductive layers.

As shown in FIG. 3C , slot 320 is an opening that extends vertically through dielectric stack layer 308 and stops at N-type doped semiconductor layer 306 . In some of the embodiments of the present invention, the manufacturing process for forming the slit 320 includes wet etching and/or dry etching, such as DRIE. Gate replacement may then be performed through gap 320 to replace dielectric stack 308 with storage stack 330 (shown in Figure 3E).

As shown in FIG. 3D , lateral recesses 322 are first formed by removing stack sacrificial layer 312 (shown in FIG. 3C ) through slit 320 . In some of these embodiments of the present invention, the stacked sacrificial layer 312 is removed by applying an etchant through the gap 320 , thereby creating lateral recesses 322 staggered between the stacked dielectric layers 310 . The etchant may include any suitable etchant that selectively etches the stacked sacrificial layer 312 with respect to the stacked dielectric layer 310 .

As shown in FIG. 3E , a stacked conductive layer 328 (including the gate electrode and the adhesive layer) is deposited through the gap 320 into the lateral recess 322 (shown in FIG. 3D ). In some of these embodiments of the invention, the gate dielectric layer 332 is deposited into the lateral recess 322 prior to stacking the conductive layer 328 , such that the stacked conductive layer 328 is deposited on the gate dielectric layer 332 . Stacked conductive layer 328 may be deposited using one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof) , such as metal layers. In some of the embodiments of the present invention, a gate dielectric layer 332, such as a high-k dielectric layer, is formed along the sidewalls of the slit 320 and at the bottom thereof. In accordance with some embodiments, a storage stack 330 comprising alternating stacked conductive layers 328 and stacked dielectric layers 310 is thereby formed instead of dielectric stack 308 (shown in FIG. 3D ).

As shown in FIG. 5A, the method 500 proceeds to operation 510 in which an insulating structure is formed extending vertically through the storage stack. In some of the embodiments of the present invention, to form the insulating structure, one or more dielectric materials are deposited into the openings to fill the openings after the storage stack is formed. As shown in FIG. 3E , an insulating structure 336 is formed extending vertically through the storage stack layer 330 , stopping on the top surface of the N-type doped semiconductor layer 306 . One or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof) may be used by Various dielectric materials (eg, silicon oxide) are deposited into the gaps 320 to fully or partially fill the gaps 320 (with or without air gaps), thereby forming insulating structures 336 . In some of these embodiments of the invention, insulating structure 336 includes gate dielectric layer 332 (eg, including a high-k dielectric) and a dielectric capping layer 334 (eg, including silicon oxide).

As shown in FIG. 3F, after insulating structure 336 is formed, local contacts including via local contact 344 and word line local contact 342 and perimeter contact 338 and perimeter contact 340 are formed. A dielectric may be deposited on top of the storage stack 330 by using one or more thin film deposition processes (eg, chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), or any combination thereof) An electrical material (eg, silicon oxide or silicon nitride), thereby forming a local dielectric layer on the storage stack layer 330 . Contact openings can be etched through the local dielectric layer (and any other interlayer dielectric layers) by using wet and/or dry etching (eg, RIE), followed by one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof) to fill the contact openings with conductive material to form the channel local contacts 344, word lines Local contact 342 as well as perimeter contact 338 and perimeter contact 340 .

As shown in FIG. 3F , a bonding layer 346 is formed over the channel local contact 344 , the word line local contact 342 , and the perimeter contacts 338 and 340 . Bonding layer 346 includes bonding contacts that are electrically connected to via local contact 344 , wordline local contact 342 , and perimeter contact 338 and perimeter contact 340 . To form bonding layer 346, an interlayer dielectric layer is deposited using one or more thin film deposition processes (eg, chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), or any combination thereof) , and using wet and/or dry etching (eg, RIE) followed by one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD) , any other suitable process, or any combination thereof) to form bonding contacts through the interlayer dielectric layer.

As shown in FIG. 5A, the method 500 proceeds to operation 512 in which the first substrate and the second substrate are bonded face-to-face such that the memory stack is over the peripheral circuitry. Bonding may include hybrid bonding. As shown in FIG. 3G , the carrier substrate 302 and the components formed thereon (eg, the storage stack 330 and the channel structures 314 formed therethrough) are turned upside down. According to some embodiments, bonding layer 346 facing downward is bonded with bonding layer 348 facing upward, ie, bonding in a face-to-face manner, thereby forming bonding interface 354 between carrier substrate 302 and silicon substrate 350 . In some of the embodiments of the present invention, a treatment process, such as plasma treatment, wet treatment and/or thermal treatment, is applied to the bonding surface prior to bonding. After bonding, the bonding contacts in bonding layer 346 and bonding layer 348 are aligned and contacted with each other so that storage stack layer 330 and channel structures 314 formed therethrough can be electrically connected to the perimeter circuit 352 and above peripheral circuits 352 .

As shown in FIG. 5A, the method 500 proceeds to operation 514 in which the second substrate, the sacrificial layer, and the first stop layer are sequentially removed to expose the ends of each of the plurality of channel structures. The removal can be performed from the backside of the second substrate. In some of the embodiments of the present invention, to sequentially remove the second substrate, the sacrificial layer and the first stop layer, remove the second substrate, stop at the second stop layer of the sacrificial layer, and remove the remainder of the sacrificial layer, at Stop at the first stop layer.

As shown in FIG. 3H , the carrier substrate 302 (and the pad oxide layer between the carrier substrate 302 and the stop layer 304 shown in FIG. 3G ) is completely removed from the backside until the stop layer 304 (eg, nitrided) silicon layer) until it stops. The carrier substrate 302 may be completely removed using chemical mechanical polishing (CMP), grinding, dry etching, and/or wet etching. In some of these embodiments of the invention, the carrier substrate 302 is peeled off. In some embodiments in which the carrier substrate 302 includes silicon and the stop layer 304 includes silicon nitride, the carrier substrate 302 is removed using silicon chemical mechanical polishing (CMP), when the stop layer 304 having a material other than silicon is reached (ie, serving as a It can be automatically stopped when the backside chemical mechanical polishing (CMP) stop layer is used. In some of these embodiments of the invention, substrate 302 (silicon substrate) is removed using wet etching through tetramethylammonium hydroxide (TMAH), when a stop layer 304 having a material other than silicon is reached (ie, serving as a backside etch stop layer), it stops automatically. The stop layer 304 can ensure complete removal of the carrier substrate 302 without concern for thickness uniformity after thinning.

As shown in FIG. 3I, a wet etch can also be used next, using suitable etchants such as phosphoric acid and hydrofluoric acid to completely remove the remaining portion of the sacrificial layer 303 (eg, the stop layer shown in FIG. 3H ) 304 and another pad oxide layer between stop layer 304 and stop layer 305) until stopped by stop layer 305 having a different material (eg, a high-k dielectric). As described above, removal of the carrier substrate 302 and sacrificial layer 303 does not affect the channel structures 314 because the individual channel structures 314 do not extend beyond the stop layer 305 into the sacrificial layer 303 or the carrier substrate 302 . As shown in FIG. 3J, in some embodiments in which stop layer 305 includes a high-k dielectric layer (as opposed to a conductive layer including metal silicide), wet and/or dry etching is used to remove completely (in FIG. 3I) stop layer 305 to expose the upper ends of channel structures 314.

As shown in FIG. 5A, the method 500 proceeds to operation 516 in which a conductive layer is formed in contact with the ends of the plurality of channel structures. In some of the embodiments of the present invention, the conductive layer includes a metal silicide layer in contact with the ends of the plurality of channel structures and the N-type doped semiconductor layer, and a metal layer in contact with the metal silicide layer. In some of these embodiments of the invention, to form the conductive layer, a portion of the storage film adjacent to the N-type doped semiconductor layer is removed to form a recess surrounding a portion of the semiconductor channel and the portion of the semiconductor channel is doped. In some of the embodiments of the invention, to form the conductive layer, a metal silicide layer is formed in contact with the doped portion of the semiconductor channel in the recess and in contact with the N-type doped semiconductor layer outside the recess.

As shown in FIG. 3J, a portion of storage layer 316, barrier layer 317, and tunnel layer 315 adjacent to N-type doped semiconductor layer 306 (shown in FIG. 3I) are removed to form an extension around semiconductor channel 318 into N The top portion of the recess 357 in the type doped semiconductor layer 306 is formed. In some of the embodiments of the present invention, two wet etching processes are performed sequentially. For example, the storage layer 316 comprising silicon nitride is selectively removed without etching the N-type doped semiconductor layer 306 comprising polysilicon using a suitable etchant such as phosphoric acid using wet etching. The etching of the storage layer 316 can be controlled by controlling the etching time and/or the etching rate so that the etching does not continue affecting the rest of the storage layer 316 surrounded by the storage stack 330 . The barrier layer 317 comprising silicon oxide and the tunneling layer 315 can then be selectively removed using wet etching using a suitable etchant such as hydrofluoric acid without etching the N-type doped semiconductor layer comprising polysilicon 306 and semiconductor channel 318. The etching of barrier layer 317 and tunnel layer 315 can be controlled by controlling the etch time and/or etch rate so that the etching does not continue to affect the rest of barrier layer 317 and tunnel layer 315 surrounded by storage stack 330 . In some of these embodiments of the invention, a single dry etch process is performed using the patterned stop layer 305 as an etch mask. For example, when dry etching is performed, the stop layer 305 may not be removed, but may instead be patterned to expose only the storage layer 316, the barrier layer 317 and the tunnel layer 315 at the upper end of the channel structure 314, While still covering other areas as an etch mask. A dry etch may then be performed to etch a portion of the storage layer 316 , the barrier layer 317 and the tunneling layer 315 adjoining the N-type doped semiconductor layer 306 . Dry etching can be controlled by controlling the etch time and/or etch rate so that the etch does not continue to affect the rest of the storage layer 316 , barrier layer 317 and tunnel layer 315 surrounded by the storage stack 330 . Once the dry etching is complete, the patterned stop layer 305 can be removed.

However, in contrast to known solutions using front-side wet etching via openings (eg, slits 320 in FIG. 3D ) through the dielectric stack 308/storage stack 330 having a high aspect ratio (eg, greater than 50) Compared with the scheme, removing the storage layer 316, the barrier layer 317 and the portion of the tunnel layer 315 adjacent to the N-type doped semiconductor layer 306 from the back side has a much simpler process difficulty and has a higher production yield. Problems caused by the larger aspect ratio of the slit 320 can be avoided, manufacturing complexity and cost can be reduced, and yield can be increased. Additionally, vertical scalability (eg, increased levels of dielectric stack 308/storage stack 330) may also be improved.

As shown in FIG. 3J , according to some embodiments, the top portion of the storage film (including barrier layer 317 , storage layer 316 , and tunnel layer 315 ) of each channel structure 314 adjacent to N-type doped semiconductor layer 306 may be removed to form a recess 357, which exposes the top portion of the semiconductor channel 318. In some of these embodiments of the invention, the top portion of semiconductor channel 318 exposed by recess 357 is doped to increase its conductivity. For example, an oblique ion implantation process may be performed to dope the top portion of semiconductor channel 318 (eg, including polysilicon) exposed by recess 357 to a desired doping concentration with any suitable dopant.

As shown in FIG. 3K , a conductive layer 359 is formed in recess 357 (shown in FIG. 3J ) surrounding and contacting the doped top portion of semiconductor channel 318 and on N-type doped semiconductor layer 306 outside recess 357 A conductive layer 359 is formed. In some of these embodiments of the invention, to form conductive layer 359 , metal silicide layer 360 is formed in recess 357 in contact with the doped top portion of semiconductor channel 318 and outside of recess 357 with N-type doping The semiconductor layer 306 is in contact, and a metal layer 362 is formed on the metal silicide layer 360 . In one example, one or more thin film deposition processes may be used (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof) , a metal film (eg, Co, Ni, or Ti) is deposited on the sidewalls and bottom surfaces of the recesses 357 and on the N-type doped semiconductor layer 306 . The metal film may be in contact with the polysilicon of the N-type doped semiconductor layer 306 and the doped top portion of the semiconductor channel 318 . A silicidation process may then be performed on the metal film and polysilicon by thermal processing (eg, annealing, sintering, or any other suitable process) to form metal along the sidewalls and bottom surfaces of the recesses 357 and on the N-type doped semiconductor layer 306 Silicide layer 360 . Then, by using one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof), Another metal film (eg, W, Al, Ti, TiN, Co, and/or Ni) is deposited on the metal silicide layer 360 to fill the remaining space of the recess 357 , thereby forming a metal layer 362 on the metal silicide layer 360 . In another example, instead of depositing two metal films separately, one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof), a single metal film (eg, Co, Ni, or Ti) is deposited into recess 357 to fill recess 357 and deposited on N-type doped semiconductor layer 306 . Then, a silicidation process may be performed on the metal film and polysilicon by thermal processing (eg, annealing, sintering, or any other suitable process) such that a portion of the metal film is formed along the sidewalls and bottom surface of the recess 357, and on the N-type doped The metal silicide layer 360 on the hetero semiconductor layer 306 and the remainder of the metal film becomes the metal layer 362 on the metal silicide layer 360 . A chemical mechanical polishing (CMP) process may be performed to remove any excess metal layer 362 . As shown in FIG. 3K , according to some embodiments, a conductive layer 359 including a metal silicide layer 360 and a metal layer 362 is thereby formed (as one example of the conductive layer 122 in the three-dimensional memory element 100 in FIG. 1A ). In some of these embodiments of the invention, the conductive layer 359 is patterned and etched so as not to cover the peripheral area.

In some of these embodiments of the invention, to form the conductive layer, doped polysilicon is deposited into the recess to contact the doped portion of the semiconductor channel, and a metal silicide is formed in contact with the doped polysilicon and the N-type doped semiconductor layer material layer. As shown in FIG. 30 , a channel plug 365 is formed in the recess 357 (shown in FIG. 3J ), which surrounds and contacts the doped top portion of the semiconductor channel 318 . As a result, the removed top portion (shown in FIG. 3H ) of the channel structure 314 adjoining the N-type doped semiconductor layer 306 is thereby replaced with a channel plug 365 in accordance with some embodiments. In some of these embodiments of the invention, to form channel plug 365, one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof) to deposit polysilicon into the recesses 357 to fill the recesses 357 , followed by a chemical mechanical polishing (CMP) process to remove any excess over the top surface of the N-type doped semiconductor layer 306 polysilicon. In some of these embodiments of the invention, in-situ doping of N-type dopants, such as P, As, or Sb, is performed to dope the channel plugs 365 when the polysilicon is deposited into the recesses 357 . Since the channel plug 365 and the doped top portion of the semiconductor channel 318 may comprise the same material (eg, doped polysilicon), the channel plug 365 may be considered part of the semiconductor channel 318 of the channel structure 314 .

As shown in FIG. 30 , a conductive layer 359 including a metal silicide layer 360 and a metal layer 362 is formed on the N-type doped semiconductor layer 306 and the channel plug 365 . In some of the embodiments of the present invention, a metal film is first deposited on the N-type doped semiconductor layer 306 and the channel plug 365, and then a silicidation process is performed to form contact with the channel plug 365 and the N-type doped semiconductor layer 306 The metal silicide layer 360. Then, another metal film may be deposited on metal silicide layer 360 to form metal layer 362 . In some of the embodiments of the present invention, a metal film is deposited on the N-type doped semiconductor layer 306 and the channel plug 365, and then a silicidation process is performed, so that the metal film is closely related to the N-type doped semiconductor layer 306 and the channel plug 365. A portion of the contact forms metal silicide layer 360 , and the remainder of the metal film becomes metal layer 362 . As shown in FIG. 30 , according to some embodiments, a conductive layer 359 including a metal silicide layer 360 and a metal layer 362 is thereby formed (as one example of the conductive layer 122 in the three-dimensional memory element 155 in FIG. 1B ). In some of these embodiments of the invention, the conductive layer 359 is patterned and etched so as not to cover the peripheral area.

As shown in FIG. 5A, the method 500 proceeds to operation 518 in which a source contact is formed over the storage stack and in contact with the N-type doped semiconductor layer. As shown in FIG. 3L , one or more interlayer dielectric layers 356 are formed on the N-type doped semiconductor layer 306 . N-type deposition can be achieved by using one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof). A dielectric material is deposited on the top surface of the doped semiconductor layer 306 to form an interlayer dielectric layer 356 . Source contact openings 358 may be formed through interlayer dielectric layer 356 and conductive layer 359 into N-type doped semiconductor layer 306 . In some of these embodiments of the invention, the source contact openings 358 are formed using wet etching and/or dry etching (eg, RIE). In some of these embodiments of the invention, the source contact opening 358 extends further into the top portion of the N-type doped semiconductor layer 306 . The etching process through the interlayer dielectric layer 356 may continue to etch a portion of the N-type doped semiconductor layer 306 . In some of these embodiments of the invention, after etching through the interlayer dielectric layer 356 and the conductive layer 359, a separate etching process is used to etch a portion of the N-type doped semiconductor layer 306.

As shown in FIG. 3M , source contacts 364 are formed in source contact openings 358 (shown in FIG. 3L ) at the backside of N-type doped semiconductor layer 306 . According to some embodiments, the source contact 364 is above the storage stack layer 330 and is in contact with the N-type doped semiconductor layer 306 . In some of these embodiments of the invention, one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof), depositing one or more conductive materials into the source contact openings 358 to fill the source contact openings 358 with an adhesive layer (eg, TiN) and a conductor layer (eg, W). A planarization process such as chemical mechanical polishing (CMP) may then be performed to remove excess conductive material such that the top surface of source contact 364 is flush with the top surface of interlayer dielectric layer 356 .

As shown in FIG. 5A, the method 500 proceeds to operation 520 in which an interconnect layer is formed over and in contact with the source contact. In some of these embodiments of the invention, a contact is formed through the N-type doped semiconductor layer and in contact with the interconnect layer such that the N-type doped semiconductor layer is electrically connected to the contact through the source contact and the interconnect layer.

As shown in FIG. 3N, a redistribution layer 370 is formed over and in contact with the source contact 364. In some of these embodiments of the invention, by using one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof), a conductive material (eg, Al) is deposited on the top surface of the interlayer dielectric layer 356 and the source contacts 364 , thereby forming the redistribution layer 370 . A passivation layer 372 may be formed on the redistribution layer 370 . In some of these embodiments of the invention, by using one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof) to deposit a dielectric material (eg, silicon nitride), thereby forming passivation layer 372 . According to some embodiments, interconnect layer 376 including interlayer dielectric layer 356 , redistribution layer 370 and passivation layer 372 is thereby formed.

As shown in FIG. 3L, contact openings 363 and contact openings 361 are formed extending through the interlayer dielectric layer 356 and the N-type doped semiconductor layer 306, respectively. In some of these embodiments of the invention, contact openings 363 and contact openings 361 are formed through interlayer dielectric layer 356 and N-type doped semiconductor layer 306 using wet etching and/or dry etching (eg, RIE). In some of these embodiments of the invention, lithography is used to pattern contact openings 363 and contact openings 361 to align with peripheral contacts 338 and 340, respectively. Etching of contact opening 363 and contact opening 361 may stop at the upper ends of perimeter contact 338 and perimeter contact 340 to expose perimeter contact 338 and perimeter contact 340 . As shown in Figure 3L, using one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof) , a spacer 367 is formed along the sidewalls of the contact opening 363 and the contact opening 361 to electrically isolate the N-type doped semiconductor layer 306 . In some of these embodiments of the present invention, after the spacers 367 are formed, the etching of the source contact openings 358 is performed so that the spacers 367 are not formed along the sidewalls of the source contact openings 358 to increase the amount of space in the source contact 364 and the contact area between the N-type doped semiconductor layer 306 .

As shown in FIG. 3M , contacts 366 and 368 are formed in contact opening 363 and contact opening 361 (shown in FIG. 3L ) at the backside of N-type doped semiconductor layer 306 , respectively. Contacts 366 and 368 extend vertically through interlayer dielectric layer 356 and N-type doped semiconductor layer 306 according to some embodiments. Contacts 366 and 368 and source contact 364 may be formed using the same deposition process to reduce the number of deposition processes. In some of these embodiments of the invention, one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof) to deposit one or more conductive materials into contact opening 363 and contact opening 361 to fill contact opening 363 and contact opening 361 with an adhesive layer (eg, TiN) and a conductor layer (eg, W). A planarization process (eg, chemical mechanical polishing (CMP)) may then be performed to remove excess conductive material such that the top surfaces of contacts 366 and 368 (and the top surface of source contact 364 ) are in contact with interlayer dielectric layer 356 the top surface is flush. In some of these embodiments of the invention, since contact opening 363 and contact opening 361 are aligned with peripheral contact 338 and peripheral contact 340, respectively, contact 366 and contact 368 are also above peripheral contact 338 and peripheral contact 340, respectively, and contact with it.

A redistribution layer 370 is also formed over and in contact with contact 366, as shown in Figure 3N. As a result, N-type doped semiconductor layer 306 may be electrically connected to perimeter contact 338 through source contact 364 , redistribution layer 370 of interconnect layer 376 , and contact 366 . In some of the embodiments of the present invention, N-type doped semiconductor layer 306 is electrically connected to peripheral circuits through source contact 364 , interconnect layer 376 , contact 366 , peripheral contact 338 , and bonding layer 346 and bonding layer 348 352.

As shown in Figure 3N, a contact pad 374 is formed over and in contact with the contact 368. In some of these embodiments of the invention, a portion of the passivation layer 372 overlying the contacts 368 is removed by wet and/or dry etching to expose a portion of the underlying redistribution layer 370 to form the contact pads 374 . As a result, contact pads 374 for pad output may be electrically connected to peripheral circuitry 352 through contacts 368 , peripheral contacts 340 , and bonding layers 346 and 348 .

It should be understood that the first stop layer in method 500 may be a first conductive layer (eg, a metal silicide layer), a portion of which remains in the conductive layer in the final product, as described below with respect to method 501 . For ease of description, details of similar operational steps between methods 500 and 501 may not be repeated. Referring to FIG. 5B, method 501 begins with operation 502 in which peripheral circuits are formed on a first substrate. The first substrate may be a silicon substrate.

As shown in FIG. 5B, the method 501 proceeds to operation step 505, in which a sacrificial layer on the second substrate, a first conductive layer on the sacrificial layer, and an N-type conductive layer on the first conductive layer are sequentially formed A doped semiconductor layer, and a dielectric stack on the N-type doped semiconductor layer. In some of the embodiments of the present invention, the first conductive layer includes a metal silicide. As shown in FIG. 3A, the stop layer 305 may be a conductive layer including metal silicide, ie, a metal silicide layer. It should be understood that the above descriptions related to forming the carrier substrate 302, the sacrificial layer 303, and the N-type doped semiconductor layer 306 may be similarly applied to the method 501, and thus, are not repeated for ease of description.

As shown in FIG. 5B, the method 501 proceeds to operation 507 in which a plurality of channels are formed each extending vertically through the dielectric stack layer and the N-type doped semiconductor layer, stopping at the first conductive layer structure. In some of the embodiments of the present invention, to form the channel structure, a plurality of channel holes are formed each extending vertically through the dielectric stack layer and the doped element layer, stopping at the first conductive layer, and then along each The sidewalls of the via holes deposit storage films and semiconductor vias.

As shown in FIG. 5B, method 501 proceeds to operation 508 in which the dielectric stack is replaced with a storage stack such that each channel structure extends vertically through the storage stack and the N-type doped semiconductor layer. In some of these embodiments of the invention, to replace the dielectric stack with the storage stack, an opening extending vertically through the dielectric stack, stopping at the N-type doped semiconductor layer, is etched, and through the opening, using The stacked conductive layer replaces the stacked sacrificial layer to form a storage stack including alternating stacked dielectric layers and stacked conductive layers.

As shown in FIG. 5B, the method 501 proceeds to operation 510, in which an insulating structure is formed extending vertically through the storage stack. In some of the embodiments of the present invention, to form the insulating structure, one or more dielectric materials are deposited into the openings to fill the openings after the storage stack is formed. As shown in FIG. 5B, method 501 proceeds to operation 512, in which the first substrate and the second substrate wafer are bonded face-to-face such that the storage stack is over the peripheral circuitry. Bonding may include hybrid bonding.

As shown in FIG. 5B, method 501 proceeds to operation 515 in which the second substrate, the sacrificial layer, and a portion of the first conductive layer are sequentially removed to expose the ends of each of the plurality of channel structures . The removal can be performed from the backside of the second substrate. In some of the embodiments of the present invention, in order to sequentially remove the second substrate, the sacrificial layer, and a portion of the first conductive layer, the second substrate is removed, stopping at the stop layer, the remaining portion of the sacrificial layer is removed, and the first conductive layer is removed. layer is stopped, and a portion of the first conductive layer is removed to expose an end of each of the plurality of channel structures.

It should be understood that the above description related to removing the carrier substrate 302 and the sacrificial layer 303 may be similarly applied to the method 501 and thus will not be repeated for ease of description. As shown in FIG. 3P , after removal of the sacrificial layer 303 (shown in FIG. 3G ), a portion of the conductive layer 305 (eg, a metal silicide layer) is removed to expose the upper ends of the channel structures 314 . Conductive layer 305 may be patterned such that a portion directly above each channel structure 314 may be removed to expose each channel structure 314 using, for example, lithography, wet etching, and/or dry etching. According to some embodiments, the remainder of the conductive layer 305 remains on the N-type doped semiconductor layer 306 .

As shown in FIG. 5B, method 501 proceeds to operation 517 in which a second conductive layer is formed in contact with the ends of the plurality of channel structures and the first conductive layer. The second conductive layer may include metal. In some of these embodiments of the invention, to form the second conductive layer, a portion of the storage film adjacent to the N-type doped semiconductor layer is etched to form a recess surrounding a portion of the semiconductor channel, the portion of the semiconductor channel being doped, And metal is deposited into the recess to contact the doped portion of the semiconductor channel, and to the outside of the recess to contact the first conductive layer.

It should be understood that the above description related to removing a portion of storage layer 316 , barrier layer 317 , and tunneling layer 315 adjoining N-type doped semiconductor layer 306 to form recess 357 may be similarly applied to method 501 , and thus for ease of description , not repeated. As shown in FIG. 3P , a metal layer 362 is formed in the recess 357 (shown in FIG. 3J ), surrounding and contacting the doped top portion of the semiconductor channel 318 , and outside the recess 357 in the conductive layer 305 (eg, metal A metal layer 362 is formed on the silicide layer). Metal layer 362 may surround and contact ends of channel structures 314 in recesses 357 (eg, doped portions of semiconductor channels 318 ). Metal layer 362 may also be over and in contact with conductive layer 305 outside of recess 357 . Metals may be deposited using one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof) A film (eg, W, Al, Ti, TiN, Co, and/or Ni) is formed to fill recess 357 and deposited on conductive layer 305 outside recess 357 , thereby forming metal layer 362 . A chemical mechanical polishing (CMP) process may be performed to remove any excess metal layer 362 . According to some embodiments, conductive layer 359 comprising metal layer 362 and conductive layer 305 is thereby formed (as one example of conductive layer 122 in stereoscopic memory element 160 in FIG. 1C ). In some of these embodiments of the invention, the conductive layer 359 is patterned and etched so as not to cover the peripheral area. Compared to method 500, the number of fabrication processes in method 501 may be reduced by retaining the first stop layer (eg, metal silicide layer) portion of the conductive layer in the final product.

As shown in FIG. 5B, method 501 proceeds to operation 518 in which a source contact is formed over the storage stack and in contact with the N-type doped semiconductor layer. As shown in FIG. 5B, method 501 proceeds to operation 520 in which an interconnect layer is formed over and in contact with the source contact. In some of these embodiments of the invention, a contact is formed through the N-type doped semiconductor layer and in contact with the interconnect layer such that the N-type doped semiconductor layer is electrically connected to the contact through the source contact and the interconnect layer .

4A-4Q illustrate a fabrication process for forming another exemplary three-dimensional memory element in accordance with some embodiments of this disclosure. 6A shows a flowchart of a method 600 for forming another exemplary three-dimensional memory element in accordance with some embodiments of this disclosure. FIG. 6B shows a flowchart of another method 601 for forming another exemplary stereoscopic memory element in accordance with some embodiments of this disclosure. Examples of stereoscopic memory elements depicted in Figures 4A-4Q, 6A, and 6B include stereoscopic memory elements 200, 255, and 260 depicted in Figures 2A-2C. 4A-4Q, 6A and 6B will be described together. It should be understood that the operational steps shown in method 600 and method 601 are not exclusive, and other operational steps may also be performed before, after, or between any of the operational steps shown. Furthermore, some of these operational steps may be performed concurrently, or in a sequence different from that shown in Figures 6A and 6B.

Referring to FIG. 6A, method 600 begins with operation 602 in which peripheral circuitry is formed on a first substrate. The first substrate may be a silicon substrate. As shown in FIG. 4G, a plurality of transistors are formed on the silicon substrate 450 using a plurality of processes including, but not limited to, lithography, etching, thin film deposition, thermal growth, implantation, chemical mechanical polishing (CMP), and any other suitable process. In some of these embodiments of the present invention, doped regions (not shown) are formed in the silicon substrate 450 by ion implantation and/or thermal diffusion, which serve, for example, as source and/or drain regions of a transistor . In some of the embodiments of the present invention, isolation regions (eg, shallow trench isolation (STI)) are also formed in the silicon substrate 450 by wet and/or dry etching and thin film deposition. The transistors may be formed on the silicon substrate 450 for peripheral circuits 452 .

As shown in FIG. 4G , a bonding layer 448 is formed over the peripheral circuit 452 . Bonding layer 448 includes bonding contacts that are electrically connected to peripheral circuitry 452 . To form bonding layer 448, an interlayer dielectric layer is deposited using one or more thin film deposition processes (eg, chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), or any combination thereof) ; using wet and/or dry etching (eg, RIE) followed by one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof) to form bonding contacts through the interlayer dielectric layers.

Channel structures each extending vertically through the storage stack layer and the P-type doped semiconductor layer having the N-well may be formed over the second substrate. As shown in FIG. 6A, the method 600 proceeds to operation 604, in which a sacrificial layer on the substrate, a first stop layer on the sacrificial layer, and an N-well on the first stop layer are sequentially formed. A P-type doped semiconductor layer and a dielectric stack layer on the P-type doped semiconductor layer. A sacrificial layer may be formed on the front surface of the second substrate on which the semiconductor element may be formed. The second substrate may be a silicon substrate. It will be appreciated that since the second substrate will be removed from the final product, the second substrate may be part of a dummy wafer, eg, a carrier substrate, made of any suitable material (eg, glass, sapphire, plastic, silicon) to reduce the cost of the second substrate. In some of the embodiments of the present invention, the substrate is a carrier substrate, the P-type doped semiconductor layer includes polysilicon, and the dielectric stack layer includes alternating stacked dielectric layers and stacked sacrificial layers. In some of the embodiments of the present invention, stacked dielectric layers and stacked sacrificial layers are alternately deposited on the P-type doped semiconductor layers to form a dielectric stack. In some of the embodiments of the invention, the sacrificial layer includes two pad oxide layers (also referred to as buffer layers) and a second stop layer sandwiched between the two pad oxide layers. In some of these embodiments of the invention, the first stop layer includes a high-k dielectric material, the second stop layer includes silicon nitride, and each of the two pad oxide layers includes silicon oxide. In some of the embodiments of the present invention, prior to forming the dielectric stack, a portion of the P-doped semiconductor layer is doped with an N-type dopant to form an N-well.

As shown in FIG. 4A , a sacrificial layer 403 is formed on the carrier substrate 402 , a stopper layer 405 is formed on the sacrificial layer 403 , and a P-type doped semiconductor layer 406 is formed on the stopper layer 405 . The P-type doped semiconductor layer 406 may include polysilicon doped with a P-type dopant (eg, B, Ga, or Al). Sacrificial layer 403 may comprise any suitable sacrificial material that may be selectively removed later and is different from the material of P-type doped semiconductor layer 406 . In some of these embodiments of the invention, the sacrificial layer 403 is a composite dielectric layer with a stop layer 404 sandwiched between two pad oxide layers. As described in detail below, stop layer 404 may act as a chemical mechanical polishing (CMP)/etch stop layer when carrier substrate 402 is removed from the backside, and thus may include any suitable material other than that of carrier substrate 402, such as nitrogen Silicon. Similarly, stop layer 405 can act as an etch stop layer when etching via holes from the front side, and thus can include a high etch selectivity relative to polysilicon (the material of P-type doped semiconductor layer 406 on stop layer 405 ) Any suitable material with properties (eg, greater than about 5). In one example, stop layer 405 may be removed from the final product later in the process, and may include a high-k dielectric, such as aluminum oxide, hafnium oxide, zirconium oxide, or titanium oxide, to name a few. In another example, at least a portion of the stop layer 405 may remain in the final product and may include metal silicides such as copper silicide, cobalt silicide, nickel silicide, titanium silicide, tungsten silicide, silver silicide, Aluminum silicide, gold silicide, platinum silicide. It should be understood that, in some examples, a pad oxide layer (eg, a silicon oxide layer) may be formed between the carrier substrate 402 and the stop layer 404 and between the stop layer 404 and the stop layer 405 to relax between the different layers stress and avoid peeling.

According to some embodiments, to form sacrificial layer 403, silicon oxide, silicon nitride, and silicon oxide are sequentially deposited on carrier substrate 402 using one or more thin film deposition processes including, but not limited to, chemical vapor deposition (CVD) , Physical Vapor Deposition (PVD), Atomic Layer Deposition (ALD) or any combination thereof. According to some embodiments, to form stop layer 405, a high-k dielectric is deposited on sacrificial layer 403 using one or more thin film deposition processes including, but not limited to, chemical vapor deposition (CVD), physical vapor deposition ( PVD), Atomic Layer Deposition (ALD), or any combination thereof. In some of these embodiments of the present invention, to form the P-type doped semiconductor layer 406, one or more thin film deposition processes (including but not limited to chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD) or any combination thereof) to deposit polysilicon on stop layer 405, and then use ion implantation and/or thermal diffusion to dope the deposited polysilicon with P-type dopants (eg, B, Ga, or Al) . In some of these embodiments of the present invention, in order to form the P-type doped semiconductor layer 406, when polysilicon is deposited on the stop layer 405, in-situ doping of a P-type dopant such as B, Ga, or Al is performed miscellaneous. In some embodiments where stop layer 405 includes a metal silicide, a metal layer is deposited on sacrificial layer 403, followed by deposition of polysilicon to form P-type doped semiconductor layer 406 on the metal layer. Then, a silicidation process is performed on the polysilicon and metal layers by thermal processing (eg, annealing, sintering, or any other suitable process) to convert the metal layer into a metal silicide layer as stop layer 405 .

As shown in FIG. 4A , a portion of the P-type doped semiconductor layer 406 is doped with an N-type dopant (eg, P, As, or Sb) to form an N-well 407 in the P-type doped semiconductor layer 406 . In some of these embodiments of the invention, ion implantation and/or thermal diffusion are used to form N-well 407 . The ion implantation and/or thermal diffusion process can be controlled to control the thickness of the N-well 407 (through the entire thickness of the P-type doped semiconductor layer 406 or through a portion thereof).

As shown in FIG. 4B , a first dielectric layer (referred to herein as a “stacked sacrificial layer” 412 ) and a second dielectric layer (referred to herein as a “stacked sacrificial layer”) and a second dielectric layer (referred to herein as A "stacked dielectric layer" 410, collectively referred to herein as a "dielectric layer pair") of the dielectric stack layers 408. According to some embodiments, the dielectric stack layer 408 includes a stacked sacrificial layer 412 and a stacked dielectric layer 410 that are staggered. Stacked dielectric layers 410 and stacked sacrificial layers 412 may be alternately deposited on P-type doped semiconductor layer 406 over carrier substrate 402 to form dielectric stack layer 408 . In some of these embodiments of the present invention, each stacked dielectric layer 410 includes a silicon oxide layer, and each stacked sacrificial layer 412 includes a silicon nitride layer. The dielectric stack layer 408 may be formed by one or more thin film deposition processes including, but not limited to, chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), or any thereof. combination. As shown in FIG. 4B , a stepped structure may be formed on the edge of the dielectric stack layer 408 . The stepped structure may be formed by performing a number of so-called "trimming-etch" loops on the dielectric layer pairs of the dielectric stack layer 408 towards the carrier substrate 402 . Dielectric stack 408 may have one or more sloped edges and a top dielectric that is shorter than the bottom dielectric pair due to repeated trim-etch cycles of the dielectric pair applied to dielectric stack 408 layer pairs, as shown in Figure 4B.

As shown in FIG. 6A, the method 600 proceeds to operation 606 in which channel structures are formed each extending vertically through the dielectric stack layer and the P-type doped semiconductor layer, stopping at a first stop layer. In some of these embodiments of the present invention, to form the channel structure, channel holes, each extending vertically through the dielectric stack layer and the P-type doped semiconductor layer, stopping at the first stop layer, are etched, and along each channel The sidewalls of the holes are sequentially deposited with a storage film and a semiconductor channel.

As shown in FIG. 4B , each via hole is an opening that extends vertically through the dielectric stack layer 408 and the P-type doped semiconductor layer 406 , stopping at the stop layer 405 . In some of these embodiments of the invention, multiple openings are formed such that each opening becomes a location for growing individual channel structures 414 in a later process. In some of the embodiments of the present invention, the fabrication process for forming the via hole of the via structure 414 includes wet etching and/or dry etching, such as DRIE. According to some embodiments, due to the etch selectivity between the material of the stop layer 405 (eg, aluminum oxide or metal silicide) and the material of the P-type doped semiconductor layer 406 (ie, polysilicon), the etching of the channel holes Continue until stopped by a stop layer 405 (eg, a high-k dielectric layer (eg, an aluminum oxide layer) or a metal silicide layer). In some of these embodiments of the invention, etch conditions (eg, etch rate and time) can be controlled to ensure that individual via holes have reached and stopped by stop layer 405, thereby connecting the via holes and the channel structures 414 formed therein Slotting variations between are minimized. It should be understood that, depending on the particular etch selectivity, one or more via holes may extend into the stop layer 405 to a small extent, which is still considered to be stopped by the stop layer 405 in the context of this disclosure.

As shown in FIG. 4B , the storage film including the barrier layer 417 , the storage layer 416 and the tunneling layer 415 and the semiconductor channel 418 are sequentially formed in this order along the sidewall and bottom surface of the channel hole. In some of these embodiments of the invention, one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof), barrier layer 417, storage layer 416, and tunneling layer 415 are deposited in this order along the sidewalls and bottom surface of the via hole to form a storage film. Then, by using one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof) Semiconductor material (eg, polysilicon (eg, undoped polysilicon)) is deposited over the tunnel layer 415 , thereby forming the semiconductor channel 418 . In some of the embodiments of the present invention, a first silicon oxide layer, a silicon nitride layer, a second silicon oxide layer and a polysilicon layer (“SONO” structure) are sequentially deposited to form the barrier layer 417 and the storage layer 416 of the storage film and tunneling layer 415 and semiconductor channel 418 .

As shown in FIG. 4B, a capping layer is formed in the via hole and over semiconductor channel 418 to fully or partially fill the via hole (eg, without or with air gaps). The dielectric may be deposited using one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof) material (eg, silicon oxide), which in turn forms the capping layer. Then, a channel plug is formed in the top portion of the channel hole. In some of these embodiments of the invention, the storage film, semiconductor channel 418 and capping layer on the top surface of the dielectric stack 408 are removed by chemical mechanical polishing (CMP), wet etching and/or dry etching A part is removed and flattened. A recess may then be formed in the top portion of the via hole by wet etching and/or dry etching a portion of the semiconductor via 418 and the capping layer in the top portion of the via hole. A semiconductor material such as polysilicon may then be deposited by passing through one or more thin film deposition processes (eg, chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), or any combination thereof) deposited into the recesses, thereby forming channel plugs. According to some embodiments, a channel structure 414 is thus formed through the dielectric stack layer 408 and the P-type doped semiconductor layer 406 , stopping at the stop layer 405 .

As shown in FIG. 6A, method 600 proceeds to operation 608, in which the dielectric stack is replaced with a storage stack, such as using a so-called "gate replacement" process, such that the channel structure extends vertically through the storage Stacked layers and P-type doped semiconductor layers. In some of these embodiments of the invention, to replace the dielectric stack with the storage stack, an opening extending vertically through the dielectric stack, stopping at the P-type doped semiconductor layer, is etched, and through the opening, using The stacked conductive layer replaces the stacked sacrificial layer to form a storage stack including interleaved stacked dielectric layers and stacked conductive layers.

As shown in FIG. 4C , slot 420 is an opening that extends vertically through dielectric stack layer 408 and stops at P-type doped semiconductor layer 406 . In some of the embodiments of the present invention, the fabrication process used to form the slit 420 includes wet etching and/or dry etching, such as DRIE. Although slit 420 is laterally aligned with N-well 407 as shown in FIG. 4C , it should be understood that slit 420 may not be laterally aligned with N-well 407 in other examples. Gate replacement may then be performed through gap 420 to replace dielectric stack 408 with storage stack 430 (shown in Figure 4E).

As shown in FIG. 4D , lateral recesses 422 are first formed by removing stack sacrificial layer 412 (shown in FIG. 4C ) through slit 420 . In some of these embodiments of the present invention, the stacked sacrificial layer 412 is removed by applying an etchant through the slits 420 , thereby creating lateral recesses 422 staggered between the stacked dielectric layers 410 . The etchant may include any suitable etchant that selectively etches the stacked sacrificial layer 412 with respect to the stacked dielectric layer 410 .

As shown in FIG. 4E , a stacked conductive layer 428 (including a gate electrode and an adhesive layer) is deposited into the lateral recess 422 (shown in FIG. 4D ) through the gap 420 . In some of these embodiments of the invention, gate dielectric layer 432 is deposited into lateral recess 422 prior to stacking conductive layer 428 , such that stacked conductive layer 428 is deposited on gate dielectric layer 432 . The stacked conductive layers may be deposited using one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof) 428 (eg, metal layer). In some of the embodiments of the present invention, a gate dielectric layer 432, such as a high-k dielectric layer, is also formed along the sidewalls of the slit 420 and at the bottom. According to some embodiments, a storage stack layer 430 comprising alternating stacked conductive layers 428 and stacked dielectric layers 410 is thus formed, which replaces dielectric stack layer 408 (shown in FIG. 4D ).

As shown in FIG. 6A, the method 600 proceeds to operation 610 in which an insulating structure is formed extending vertically through the storage stack. In some of the embodiments of the present invention, to form the insulating structure, one or more dielectric materials are deposited into the openings to fill the openings after the storage stack is formed. As shown in FIG. 4E , an insulating structure 436 is formed extending vertically through the storage stack layer 430 , stopping on the top surface of the P-type doped semiconductor layer 406 . One or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof) may be used for Various dielectric materials (eg, silicon oxide) are deposited into the gaps 420 to fully or partially fill the gaps 420 (with or without air gaps), thereby forming insulating structures 436 . In some of these embodiments of the invention, the insulating structure 436 includes a gate dielectric layer 432 (eg, including a high-k dielectric) and a dielectric capping layer 434 (eg, including silicon oxide).

As shown in FIG. 4F, after insulating structure 436 is formed, local contacts including via local contact 444 and word line local contact 442 and perimeter contact 438, perimeter contact 439, and perimeter contact 440 are formed. A dielectric may be deposited on top of the storage stack 430 by using one or more thin film deposition processes (eg, chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), or any combination thereof) An electrical material (eg, silicon oxide or silicon nitride), thereby forming a local dielectric layer on the storage stack 430 . Contact openings can be etched through the local dielectric layer (and any other interlayer dielectric layers) by using wet and/or dry etching (eg, RIE), followed by one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof) to fill the contact openings with conductive material to form the channel local contacts 444, word lines Local contact 442 and perimeter contact 438 , perimeter contact 439 and perimeter contact 440 .

As shown in FIG. 4F , a bonding layer 446 is formed over the channel local contact 444 , the word line local contact 442 , and the perimeter contacts 438 , 439 and 440 . Bonding layer 446 includes bonding contacts electrically connected to via local contact 444 , wordline local contact 442 , and perimeter contact 438 , perimeter contact 439 , and perimeter contact 440 . To form bonding layer 446, an interlayer dielectric layer is deposited using one or more thin film deposition processes (eg, chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), or any combination thereof) , and using wet and/or dry etching (eg, RIE) followed by one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD) , any other suitable process, or any combination thereof) to form bonding contacts through the interlayer dielectric layer.

As shown in FIG. 6A, the method 600 proceeds to operation 612 in which the first substrate and the second substrate are bonded face-to-face such that the memory stack is over the peripheral circuitry. Bonding may include hybrid bonding. As shown in FIG. 4G , the carrier substrate 402 and the components formed thereon (eg, the storage stack 430 and the channel structures 414 formed therethrough) are turned upside down. According to some embodiments, the bonding layer 446 facing downward is bonded with the bonding layer 448 facing upward, ie, bonding in a face-to-face manner, thereby forming a bonding interface 454 between the carrier substrate 402 and the silicon substrate 450 . In some of the embodiments of the present invention, a treatment process, such as plasma treatment, wet treatment and/or thermal treatment, is applied to the bonding surface prior to bonding. After bonding, the bonding contacts in bonding layer 446 and bonding layer 448 are aligned and contacted with each other so that storage stack layer 430 and channel structures 414 formed therethrough can be electrically connected to Peripheral circuit 452 and above peripheral circuit 452 .

As shown in FIG. 6A, the method 600 proceeds to operation 614 in which the second substrate, the sacrificial layer, and the first stop layer are sequentially removed to expose the ends of each of the plurality of channel structures. The removal can be performed from the backside of the second substrate. In some of the embodiments of the present invention, to sequentially remove the second substrate, the sacrificial layer, and the first stop layer, remove the second substrate, stop at the second stop layer of the sacrificial layer, and remove the remainder of the sacrificial layer, at Stop at the first stop layer.

As shown in FIG. 4H , the carrier substrate 402 (and the pad oxide layer between the carrier substrate 402 and the stop layer 404 shown in FIG. 4G ) is completely removed from the backside until the stop layer 404 (eg, nitrogen silicon layer) until it stops. The carrier substrate 402 may be completely removed using chemical mechanical polishing (CMP), grinding, dry etching, and/or wet etching. In some of these embodiments of the invention, the carrier substrate 402 is peeled off. In some embodiments in which the carrier substrate 402 includes silicon and the stop layer 404 includes silicon nitride, the carrier substrate 402 is removed using chemical mechanical polishing (CMP) of silicon, when the stop layer 404 having a material other than silicon (ie, serving as a It can be automatically stopped when the backside chemical mechanical polishing (CMP) stop layer is used. In some of these embodiments of the invention, wet etch through TMAH is used to remove substrate 402 (silicon substrate), which when reaching stop layer 404 having a material other than silicon (ie, serving as a backside etch stop layer) stop automatically. The stop layer 404 can ensure complete removal of the carrier substrate 402 without concern for thickness uniformity after thinning.

As shown in Figure 4I, a wet etch can then also be used to completely remove the remaining portion of the sacrificial layer 403 (eg, the stop layer 404 shown in Figure 4H using suitable etchants such as phosphoric acid and hydrofluoric acid) and another pad oxide layer between stop layer 404 and stop layer 405) until stopped by stop layer 405 having a different material (eg, a high-k dielectric). As described above, removal of the carrier substrate 402 and sacrificial layer 403 does not affect the channel structures 414 because the individual channel structures 414 do not extend beyond the stop layer 405 into the sacrificial layer 403 or the carrier substrate 402 . As shown in FIG. 4J, in some embodiments in which the stop layer 405 includes a high-k dielectric (as opposed to a conductive layer including a metal silicide), wet and/or dry etching is used to remove completely (in FIG. 4I ). shown) stop layer 405 to expose the upper ends of channel structures 414.

As shown in FIG. 6A, the method 600 proceeds to operation 616 in which a conductive layer is formed in contact with the ends of the plurality of channel structures. In some of the embodiments of the present invention, the conductive layer includes a metal silicide layer in contact with the ends of the plurality of channel structures and the P-type doped semiconductor layer, and a metal layer in contact with the metal silicide layer. In some of these embodiments of the invention, to form the conductive layer, a portion of the storage film adjacent to the P-type doped semiconductor layer is removed to form a recess surrounding a portion of the semiconductor channel, and the portion of the semiconductor channel is doped. In some of the embodiments of the invention, to form the conductive layer, a metal silicide layer is formed in contact with the doped portion of the semiconductor channel in the recess and in contact with the P-type doped semiconductor layer outside the recess.

As shown in Figure 4J, a portion of the storage layer 416, barrier layer 417, and tunnel layer 415 adjacent to the P-type doped semiconductor layer 406 (shown in Figure 4I) is removed to form an extension around the semiconductor channel 418 into P The top portion of the recess 457 in the type doped semiconductor layer 406 is formed. In some of the embodiments of the present invention, two wet etching processes are performed sequentially. For example, wet etching is used to selectively remove the storage layer 416 comprising silicon nitride using a suitable etchant such as phosphoric acid, without etching the P-type doped semiconductor layer 406 comprising polysilicon. The etching of the storage layer 416 can be controlled by controlling the etching time and/or the etching rate so that the etching does not continue to affect the rest of the storage layer 416 surrounded by the storage stack 430 . The barrier layer 417 comprising silicon oxide and the tunneling layer 415 can then be selectively removed using a wet etch using a suitable etchant such as hydrofluoric acid, without etching the P-type doped semiconductor layer comprising polysilicon 406 and semiconductor channel 418. The etching of barrier layer 417 and tunnel layer 415 can be controlled by controlling the etch time and/or etch rate so that the etching does not continue to affect the rest of barrier layer 417 and tunnel layer 415 surrounded by storage stack 430 . In some of these embodiments of the invention, a single dry etch process is performed using the patterned stop layer 405 as an etch mask. For example, when dry etching is performed, the stop layer 405 may not be removed, but may instead be patterned to expose only the storage layer 416, the barrier layer 417 and the tunnel layer 415 at the upper end of the channel structure 414, While still covering other areas as an etch mask. A dry etch may then be performed to etch a portion of the storage layer 416 , the barrier layer 417 and the tunneling layer 415 adjacent to the P-type doped semiconductor layer 406 . Dry etching can be controlled by controlling the etch time and/or etch rate so that the etch does not continue to affect the rest of the storage layer 416 , barrier layer 417 and tunnel layer 415 surrounded by the storage stack 430 . Once the dry etching is complete, the patterned stop layer 405 can be removed.

However, in contrast to known methods using front-side wet etching via openings (eg, slits 420 in FIG. 4D ) through the dielectric stack 408/storage stack 430 with larger aspect ratios (eg, greater than 50) Removing the portion of the storage layer 416, barrier layer 417, and tunneling layer 415 adjacent to the P-type doped semiconductor layer 406 from the backside is much less challenging and has a higher production yield than the solution. By avoiding the problems introduced by the high aspect ratio of the slit 420, manufacturing complexity and cost can be reduced, and yield can be increased. Additionally, vertical scalability (eg, increased levels of dielectric stack 408/storage stack 430) may also be improved.

As shown in FIG. 4J , according to some embodiments, the top portion of the storage film (including barrier layer 417 , storage layer 416 , and tunnel layer 415 ) of each channel structure 414 adjacent to P-type doped semiconductor layer 406 may be removed to form Recess 457 , which exposes the top portion of semiconductor channel 418 . In some of these embodiments of the invention, the top portion of the semiconductor channel 418 exposed by the recess 457 is doped to increase its conductivity. For example, an oblique ion implantation process may be performed to dope the top portion of semiconductor channel 418 (eg, including polysilicon) exposed by recess 457 to a desired doping concentration with any suitable dopant.

As shown in FIG. 4K , a conductive layer 459 is formed in recess 457 (shown in FIG. 4J ), surrounding and contacting the doped top portion of semiconductor channel 418 , and outside recess 457 in P-type doped semiconductor layer 406 A conductive layer 459 is formed thereon. In some of these embodiments of the invention, to form conductive layer 459 , metal silicide layer 476 is formed in contact with the doped top portion of semiconductor channel 418 in recess 457 and outside of recess 457 with P-type doping The semiconductor layer 406 is in contact, and a metal layer 478 is formed on the metal silicide layer 476 . In one example, one or more thin film deposition processes may be used (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof) , to deposit a metal film (eg, Co, Ni, or Ti) on the sidewalls and bottom surfaces of the recesses 457 and on the P-type doped semiconductor layer 406 . The metal film may be in contact with the polysilicon of the P-type doped semiconductor layer 406 and the doped top portion of the semiconductor channel 418 . Then, a silicidation process may be performed on the metal film and polysilicon by thermal processing (eg, annealing, sintering, or any other suitable process) to form metal along the sidewalls and bottom surfaces of the recesses 457 and on the P-type doped semiconductor layer 406 Silicide layer 476 . Then, by using one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof) Another metal film (eg, W, Al, Ti, TiN, Co, and/or Ni) is deposited on the metal silicide layer 476 to fill the remaining space of the recess 457 , thereby forming a metal layer 478 on the metal silicide layer 476 . In another example, instead of depositing two metal films separately, one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof), a single metal film (eg, Co, Ni, or Ti) is deposited into recess 457 to fill recess 457 and deposited on P-type doped semiconductor layer 406 . Then, a silicidation process may be performed on the metal film and polysilicon by thermal processing (eg, annealing, sintering, or any other suitable process) such that a portion of the metal film is formed along the sidewalls and bottom surface of the recess 457 and on the P-type doped semiconductor Metal silicide layer 476 on layer 406 , and the remainder of the metal film becomes metal layer 478 on metal silicide layer 476 . A chemical mechanical polishing (CMP) process may be performed to remove any excess metal layer 478 . As shown in FIG. 4K , according to some embodiments, a conductive layer 459 including a metal silicide layer 476 and a metal layer 478 is thereby formed (as an example of the conductive layer 222 in the three-dimensional memory element 200 in FIG. 2A ). In some of these embodiments of the invention, the conductive layer 459 is patterned and etched so as not to cover the peripheral area.

In some of these embodiments of the invention, to form the conductive layer, doped polysilicon is deposited into the recess to contact the doped portion of the semiconductor channel, and a metal silicide is formed in contact with the doped polysilicon and the P-type doped semiconductor layer material layer. As shown in FIG. 4P , a channel plug 480 is formed in the recess 457 (shown in FIG. 4J ), which surrounds and contacts the doped top portion of the semiconductor channel 418 . As a result, the removed top portion of the channel structure 414 adjoining the P-type doped semiconductor layer 406 (shown in FIG. 4H ) is thereby replaced with a channel plug 480 in accordance with some embodiments. In some of these embodiments of the invention, to form channel plug 480, one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof), polysilicon is deposited into the recesses 457 to fill the recesses 457 , followed by a chemical mechanical polishing (CMP) process to remove any excess above the top surface of the P-type doped semiconductor layer 406 of polysilicon. In some of these embodiments of the invention, in-situ doping of a P-type dopant, such as B, Ga, or Al, is performed to dope the channel plug 480 when the polysilicon is deposited into the recess 457 . miscellaneous. Since the channel plug 480 and the doped top portion of the semiconductor channel 418 may comprise the same material (eg, doped polysilicon), the channel plug 480 may be considered part of the semiconductor channel 418 of the channel structure 414 .

As shown in FIG. 4P , a conductive layer 459 including a metal silicide layer 476 and a metal layer 478 is formed on the P-type doped semiconductor layer 406 and the channel plug 480 . In some of the embodiments of the present invention, a metal film is first deposited on the P-type doped semiconductor layer 406 and the channel plug 480 , and then a silicidation process is performed to form contact with the channel plug 480 and the P-type doped semiconductor layer 406 . Metal silicide layer 476 . Then, another metal film may be deposited on metal silicide layer 476 to form metal layer 478 . In some of the embodiments of the present invention, a metal film is deposited on the P-type doped semiconductor layer 406 and the channel plug 480, and then a silicidation process is performed, so that the metal film is closely related to the P-type doped semiconductor layer 406 and the channel plug 480. A portion of the contact forms metal silicide layer 476 , and the remainder of the metal film becomes metal layer 478 . As shown in FIG. 4P , according to some embodiments, a conductive layer 459 including a metal silicide layer 476 and a metal layer 478 is thereby formed (as an example of the conductive layer 222 in the three-dimensional memory element 255 in FIG. 2B ). In some of these embodiments of the invention, the conductive layer 459 is patterned and etched so as not to cover the peripheral area.

As shown in FIG. 6A, the method 600 proceeds to operation 618 where a first source contact is formed over the storage stack and in contact with the P-type doped semiconductor layer and over the storage stack And it is in contact with the second source electrode in contact with the N well. As shown in FIG. 4L , one or more interlayer dielectric layers 456 are formed on the P-type doped semiconductor layer 406 . Particles can be deposited on P by using one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof). A dielectric material is deposited on the top surface of the doped semiconductor layer 406 to form an interlayer dielectric layer 456 .

As shown in FIG. 4M , source contact openings 458 may be formed through interlayer dielectric layer 456 and conductive layer 459 into P-type doped semiconductor layer 406 . In some of these embodiments of the invention, the source contact openings 458 are formed using wet etching and/or dry etching (eg, RIE). In some of these embodiments of the invention, the source contact opening 458 extends further into the top portion of the P-type doped semiconductor layer 406 . The etching process through the interlayer dielectric layer 456 and the conductive layer 459 may continue to etch a portion of the P-type doped semiconductor layer 406 . In some of these embodiments of the invention, after etching through the interlayer dielectric layer 456 and the conductive layer 459, a separate etching process is used to etch a portion of the P-type doped semiconductor layer 406.

As shown in FIG. 4M , source contact openings 465 may be formed through interlayer dielectric layer 456 and conductive layer 459 into N well 407 . In some of these embodiments of the invention, the source contact openings 465 are formed using wet etching and/or dry etching (eg, RIE). In some of these embodiments of the invention, the source contact opening 465 extends further into the top portion of the N-well 407 . The etching process through interlayer dielectric layer 456 and conductive layer 459 may continue to etch a portion of N well 407 . In some of these embodiments of the invention, after etching through interlayer dielectric layer 456 and conductive layer 459, a separate etch process is used to etch a portion of N-well 407. The etching of the source contact openings 458 may be performed after the etching of the source contact openings 465, and vice versa. It should be appreciated that in some examples, source contact openings 458 and source contact openings 465 may be etched through the same etch process to reduce the number of etch processes.

As shown in FIG. 4N , source contact 464 and source contact opening 478 are formed in source contact openings 458 and 465 (shown in FIG. 4M ), respectively, at the backside of P-type doped semiconductor layer 406 . According to some embodiments, the source contact 464 is over the storage stack layer 430 and is in contact with the P-type doped semiconductor layer 406 . According to some embodiments, source contact 479 is above storage stack 430 and in contact with N-well 407 . In some of these embodiments of the invention, one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof) to deposit one or more conductive materials into source contact openings 458 and 465 to fill source contact openings 458 and 465 with an adhesive layer (eg, TiN) and a conductor layer (eg, W). A planarization process such as chemical mechanical polishing (CMP) may then be performed to remove excess conductive material such that the top surfaces of source contact 464 and source contact 478 are flush with each other and with interlayer dielectric layer 456 Top surface is flush. It should be appreciated that in some examples, source contact 464 and source contact 478 may be formed through the same deposition and chemical mechanical polishing (CMP) process to reduce steps in the fabrication process.

As shown in FIG. 6A, the method 600 proceeds to operation 620 in which an interconnect layer is formed over and in contact with the first source contact and the second source contact. In some of the embodiments of the invention, the interconnect layer includes first and second interconnects over and in contact with the first and second source contacts, respectively interconnection.

As shown in FIG. 40, a redistribution layer 470 is formed over and in contact with source contact 464 and source contact 478. In some of these embodiments of the invention, by using one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof) to deposit a conductive material (eg, Al) on the top surfaces of interlayer dielectric layer 456 and source contact 364 , thereby forming redistribution layer 470 . In some of these embodiments of the invention, the redistribution layer 470 is patterned through a lithography and etching process to form a first interconnect 470-1 over and in contact with the source contact 464 and at the source contact 479 A second interconnect 470-2 above and in contact therewith. The first interconnect 470-1 and the second interconnect 470-2 may be electrically isolated from each other. A passivation layer 472 may be formed on the redistribution layer 470 . In some of these embodiments of the invention, by using one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof) to deposit a dielectric material (eg, silicon nitride) to form passivation layer 472 . According to some embodiments, interconnect layer 477 including interlayer dielectric layer 456 , redistribution layer 470 and passivation layer 472 is thereby formed.

As shown in FIG. 4L, a contact opening 460, a contact opening 461, and a contact opening 463 are formed each extending through the interlayer dielectric layer 456 and the P-type doped semiconductor layer 406. As shown in FIG. In some of these embodiments of the present invention, contact openings 460 , contact openings 461 , and Contact opening 463 . In some of these embodiments of the invention, contact opening 460, contact opening 461, and contact opening 463 are patterned using lithography to align with perimeter contact 438, perimeter contact 440, and perimeter contact 439, respectively. Etching of contact opening 460 , contact opening 461 , and contact opening 463 may stop at the upper ends of perimeter contact 438 , perimeter contact 440 , and perimeter contact 439 to expose perimeter contact 438 , perimeter contact 440 , and perimeter contact 439 . The etching of the contact opening 460, the contact opening 461, and the contact opening 463 may be performed through the same etching process to reduce the number of etching processes. It will be appreciated that due to the different etch depths, the etching of contact opening 460, contact opening 461 and contact opening 463 may be performed before (but not simultaneously) the etching of source contact opening 465, and vice versa.

4M, using one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof) , spacers 462 are formed along the sidewalls of the contact opening 460 , the contact opening 461 , the contact opening 463 and the source contact opening 465 to electrically isolate the P-type doped semiconductor layer 406 . In some of the embodiments of the present invention, spacers 462 are formed along the sidewalls of contact openings 460, 461 and 463, and source contact openings 465 through the same deposition process to reduce the number of manufacturing processes. In some of these embodiments of the invention, the etching of the source contact openings 458 is performed after the spacers 462 are formed so that the spacers 462 are not formed along the sidewalls of the source contact openings 458 to increase the amount of space between the source contacts 464 and 458. The contact area between the P-type doped semiconductor layers 406 .

As shown in FIG. 4N, contacts 466, 468, and 469 are formed in contact opening 460, contact opening 461, and contact opening 463 (shown in FIG. 4M) at the backside of P-type doped semiconductor layer 406, respectively. Contact 466 , contact 468 , and contact 469 extend vertically through interlayer dielectric layer 456 and P-type doped semiconductor layer 406 according to some embodiments. Contacts 466, 468 and 469, and source contacts 464 and 478 may be formed using the same deposition process to reduce the number of deposition processes. In some of these embodiments of the invention, one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof) to deposit one or more conductive materials into contact opening 460, contact opening 461, and contact opening 463 to fill contact opening 460, contact opening 460, contact opening 460, contact opening 460 with an adhesive layer (eg, TiN) and a conductor layer (eg, W) 461 and contact opening 463. A planarization process (eg, chemical mechanical polishing (CMP)) may then be performed to remove excess conductive material such that the top surfaces of contacts 466 , 468 , and 469 (and the tops of source contacts 464 and 478 ) surface) is flush with the top surface of the interlayer dielectric layer 456. In some of these embodiments of the invention, since contact opening 460, contact opening 461, and contact opening 463 are aligned with peripheral contact 438, peripheral contact 440, and peripheral contact 439, respectively, contact 466, contact 468, and contact 469 are also Above and in contact with perimeter contact 438, perimeter contact 440, and perimeter contact 439, respectively.

As shown in FIG. 40, a first interconnect 470-1 of redistribution layer 470 is formed over and in contact with contact 466. As a result, the P-type doped semiconductor layer 406 may be electrically connected to the peripheral contact 438 through the source contact 464 , the first interconnect 470 - 1 of the interconnect layer 477 , and the contact 466 . In some of these embodiments of the invention, P-type doped semiconductor layer 406 penetrates source contact 464, first interconnect 470-1 of interconnect layer 477, contact 466, perimeter contact 438, and bonding layer 446 and keys The bonding layer 448 is electrically connected to the peripheral circuit 452 . Similarly, a second interconnect 470-2 of redistribution layer 470 is formed over and in contact with contact 469. As a result, N-well 407 may be electrically connected to perimeter contact 438 through source contact 479 , second interconnect 470 - 2 of interconnect layer 477 , and contact 469 . In some of these embodiments of the invention, N-well 407 is electrically conductive through source contact 479 , second interconnect 470 - 2 of interconnect layer 477 , contact 469 , perimeter contact 439 , and bonding layers 446 and 448 Connected to peripheral circuit 452 .

As shown in FIG. 40, a contact pad 474 is formed over and in contact with the contact 468. In some of these embodiments of the invention, a portion of the passivation layer 472 overlying the contacts 468 is removed by wet etching and/or dry etching to expose a portion of the underlying redistribution layer 470 to form the contact pads 474 . As a result, contact pads 474 for pad output may be electrically connected to peripheral circuitry 452 through contacts 468 , peripheral contacts 440 , and bonding layers 446 and 448 .

It should be understood that the first stop layer in method 600 may be a first conductive layer (eg, a metal silicide layer), a portion of which remains in the conductive layer in the final product, as described below with respect to method 601 . For ease of description, details of similar operational steps between methods 600 and 601 may not be repeated. Referring to FIG. 6B, method 601 begins with operation 602 in which peripheral circuits are formed on a first substrate. The first substrate may be a silicon substrate.

As shown in FIG. 6B , the method 601 proceeds to operation step 605 , in which a sacrificial layer on the second substrate, a first conductive layer on the sacrificial layer, and a conductive layer with N on the first conductive layer are sequentially formed. A P-type doped semiconductor layer of the well, and a dielectric stack layer on the P-type doped semiconductor layer. In some of the embodiments of the present invention, the first conductive layer includes a metal silicide. As shown in FIG. 4A , the stop layer 405 may be a conductive layer including metal silicide, ie, a metal silicide layer. It should be understood that the above descriptions related to forming the carrier substrate 402 , the sacrificial layer 403 and the P-type doped semiconductor layer 406 may be similarly applied to the method 601 and thus will not be repeated for ease of description.

As shown in FIG. 6B, method 601 proceeds to operation 607 in which a plurality of channels are formed each extending vertically through the dielectric stack layer and the P-type doped semiconductor layer, stopping at the first conductive layer structure. In some of the embodiments of the present invention, to form the channel structure, a plurality of channel holes are formed each extending vertically through the dielectric stack layer and the doped element layer, stopping at the first conductive layer, and along each channel The sidewalls of the holes are used to sequentially deposit the storage film and the semiconductor channel.

As shown in FIG. 6B, method 601 proceeds to operation 608 where the dielectric stack is replaced with a storage stack such that each channel structure extends vertically through the storage stack and the P-type doped semiconductor layer. In some of these embodiments of the invention, to replace the dielectric stack with the storage stack, an opening extending vertically through the dielectric stack, stopping at the P-type doped semiconductor layer, is etched, and through the opening, using The stacked conductive layer replaces the stacked sacrificial layer to form a storage stack including interleaved stacked dielectric layers and stacked conductive layers.

As shown in FIG. 6B, the method 601 proceeds to operation 610, in which an insulating structure is formed extending vertically through the storage stack. In some of the embodiments of the present invention, to form the insulating structure, one or more dielectric materials are deposited into the openings to fill the openings after the storage stack is formed. As shown in FIG. 6B, the method 601 proceeds to operation 612, where the first substrate and the second substrate wafer are bonded face-to-face such that the storage stack is over the peripheral circuitry. Bonding may include hybrid bonding.

As shown in FIG. 6B, method 601 proceeds to operation 615 in which the second substrate, the sacrificial layer, and a portion of the first conductive layer are sequentially removed to expose the ends of each of the plurality of channel structures . The removal can be performed from the backside of the second substrate. In some of the embodiments of the present invention, in order to sequentially remove the second substrate, the sacrificial layer, and a portion of the first conductive layer, the second substrate is removed, stopping at the stop layer, the remaining portion of the sacrificial layer is removed, and the first conductive layer is removed. layer is stopped, and a portion of the first conductive layer is removed to expose an end of each of the plurality of channel structures.

It should be understood that the above description related to the removal of the carrier substrate 402 and the sacrificial layer 403 may be similarly applied to the method 601 and thus will not be repeated for ease of description. As shown in FIG. 4Q , after removal of the sacrificial layer 403 (shown in FIG. 4G ), a portion of the conductive layer 405 (eg, a metal silicide layer) is removed to expose the upper ends of the channel structures 414 . Conductive layer 405 may be patterned such that a portion directly above each channel structure 414 may be removed to expose each channel structure 414 using, for example, lithography, wet etching, and/or dry etching. According to some embodiments, the remaining portion of conductive layer 405 remains on P-type doped semiconductor layer 406 .

As shown in FIG. 6B, method 601 proceeds to operation 617 in which a second conductive layer is formed in contact with the ends of the plurality of channel structures and the first conductive layer. The second conductive layer may include metal. In some of these embodiments of the invention, to form the second conductive layer, a portion of the storage film adjacent to the P-type doped semiconductor layer is etched to form a recess surrounding a portion of the semiconductor channel, the portion of the semiconductor channel being doped, And metal is deposited into the recess to contact the doped portion of the semiconductor channel, and to the outside of the recess to contact the first conductive layer.

It should be understood that the above description related to the removal of storage layer 416 , barrier layer 417 , and a portion of tunnel layer 415 adjoining P-type doped semiconductor layer 406 to form recess 457 may be similarly applied to method 601 , and therefore will not be used for ease of description. Repeat again. As shown in FIG. 4Q , a metal layer 478 is formed in the recess 457 (shown in FIG. 4J ) surrounding and contacting the doped top portion of the semiconductor channel 418 , and outside the recess 457 in the conductive layer 405 (eg, metal silicide) A metal layer 478 is formed thereon. Metal layer 478 may surround and contact ends of channel structures 414 in recesses 457 (eg, doped portions of semiconductor channels 418 ). Metal layer 478 may also be over and in contact with conductive layer 405 on the exterior of recess 457 . Metal films may be deposited using one or more thin film deposition processes (eg, atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), any other suitable process, or any combination thereof) (eg, W, Al, Ti, TiN, Co, and/or Ni) to fill recess 457 and deposit on conductive layer 405 outside recess 457 , thereby forming metal layer 478 . A chemical mechanical polishing (CMP) process may be performed to remove any excess metal layer 478 . According to some embodiments, conductive layer 459 comprising metal layer 478 and conductive layer 405 is thereby formed (as one example of conductive layer 222 in 3D memory element 260 in Figure 2C). In some of these embodiments of the invention, the conductive layer 459 is patterned and etched so as not to cover the peripheral area. Compared to method 600, the number of fabrication processes in method 601 may be reduced by retaining the first stop layer (eg, metal silicide layer) portion of the conductive layer in the final product.

As shown in FIG. 6B , method 601 proceeds to operation 618 where a first source contact is formed over the storage stack and in contact with the P-type doped semiconductor layer, and over the storage stack and A second source contact is in contact with the N well. As shown in FIG. 6B, the method 601 proceeds to operation 620 in which an interconnect layer is formed over and in contact with the first source contact and the second source contact. In some of these embodiments of the invention, the interconnect layer includes a first interconnect over and in contact with the first source contact, and a second interconnect over and in contact with the second source contact. In some of the embodiments of the invention, a first contact is formed through the P-type doped semiconductor layer and in contact with the first interconnect such that the P-type doped semiconductor layer is electrically connected through the first source contact and the first interconnect Sexually connected to the first contact. In some of the embodiments of the present invention, a second contact is formed through the P-type doped semiconductor layer and in contact with the second interconnect such that the N well is electrically connected to the first through the second source contact and the second interconnect Second contact.

According to one aspect of this disclosure, a method for forming a 3D memory element is disclosed. A sacrificial layer on the substrate, a first stop layer on the sacrificial layer, an N-type doped semiconductor layer on the first stop layer, and a dielectric stack layer on the N-type doped semiconductor layer are sequentially formed. A plurality of channel structures are formed each extending vertically through the dielectric stack layer and the N-type doped semiconductor layer, stopping at the first stop layer. The dielectric stack is replaced with a storage stack such that each channel structure of the plurality of channel structures extends vertically through the storage stack and the N-type doped semiconductor layer. The substrate, the sacrificial layer, and the first stop layer are sequentially removed to expose the ends of each of the plurality of channel structures. A conductive layer is formed in contact with the ends of the plurality of channel structures.

In some of the embodiments of the invention, the conductive layer includes: a metal silicide layer in contact with the ends of the plurality of channel structures and the N-type doped semiconductor layer; and a metal layer in contact with the metal silicide layer.

In some of the embodiments of the present invention, to form the plurality of channel structures, a plurality of channel holes each extending vertically through the dielectric stack layer and the N-type doped semiconductor layer, stopping at the first stop layer, are etched, and The storage film and semiconductor channel are sequentially deposited along the sidewalls of each of the plurality of via holes.

In some of these embodiments of the invention, to form the conductive layer, a portion of the storage film adjacent to the N-type doped semiconductor layer is etched to form a recess surrounding a portion of the semiconductor channel and the portion of the semiconductor channel is doped.

In some of the embodiments of the invention, to form the conductive layer, a metal silicide layer is formed in the recess in contact with the doped portion of the semiconductor channel and outside the recess in contact with the N-type doped semiconductor layer.

In some of these embodiments of the invention, to form the conductive layer, doped polysilicon is deposited into the recess to make contact with the doped portion of the semiconductor channel and to form contact with the doped polysilicon and the N-type doped semiconductor layer. metal silicide layer.

In some of the embodiments of the invention, the sacrificial layer includes a second stop layer. In some of these embodiments of the invention, to sequentially remove the substrate, the sacrificial layer, and the first stop layer, the substrate is removed, stopping at the second stop layer, and the remainder of the sacrificial layer is removed, stopping at the first stop layer.

In some of the embodiments of the present invention, the N-type doped semiconductor layer includes polysilicon, and the dielectric stack layer includes alternating stacked dielectric layers and stacked sacrificial layers. In some of the embodiments of the invention, to replace the dielectric stack with the storage stack, an opening extending vertically through the dielectric stack, stopping at the N-type doped semiconductor layer, is etched, and through the opening, using The stacked conductive layer replaces the stacked sacrificial layer to form a storage stack including interleaved stacked dielectric layers and stacked conductive layers.

In some of these embodiments of the invention, after replacing the dielectric stack layer with the storage stack layer, one or more dielectric materials are deposited into the openings to form insulating structures extending vertically through the storage stack layer.

In some of the embodiments of the present invention, after forming the conductive layer, a source contact is formed in contact with the N-type doped semiconductor layer.

In some of the embodiments of the invention, the interconnect layer is formed in contact with the source electrode, and the contact is formed through the N-type doped semiconductor layer and in contact with the interconnect layer such that the N-type doped semiconductor layer penetrates the source electrode The contact and interconnect layers are electrically connected to the contact.

In some of the embodiments of the present invention, the first stop layer includes a high-k dielectric material.

According to another aspect of the present disclosure, a method for forming a 3D memory element is disclosed. A sacrificial layer on the substrate, a first conductive layer on the sacrificial layer, an N-type doped semiconductor layer on the first conductive layer, and a dielectric stack layer on the N-type doped semiconductor layer are sequentially formed. A plurality of channel structures are formed each extending vertically through the dielectric stack layer and the N-type doped semiconductor layer, stopping at the first conductive layer. The dielectric stack is replaced with a storage stack such that each channel structure of the plurality of channel structures extends vertically through the storage stack and the N-type doped semiconductor layer. The substrate, the sacrificial layer, and a portion of the first conductive layer are sequentially removed to expose ends of each of the plurality of channel structures. A conductive layer is formed in contact with the ends of the plurality of channel structures and the first conductive layer.

In some of the embodiments of the present invention, the first conductive layer includes a metal silicide, and the second conductive layer includes a metal.

In some of the embodiments of the invention, to form the plurality of channel structures, a plurality of channel holes each extending vertically through the dielectric stack layer and the N-type doped semiconductor layer, stopping at the first conductive layer, are etched, and The storage film and semiconductor channel are sequentially deposited along the sidewalls of each of the plurality of via holes.

In some of these embodiments of the invention, to form the conductive layer, a portion of the storage film adjacent to the N-type doped semiconductor layer is etched to form a recess surrounding a portion of the semiconductor channel, the portion of the semiconductor channel is doped, and Metal is deposited into the recess to contact the doped portion of the semiconductor channel and to the outside of the recess to contact the first conductive layer.

In some of the embodiments of the invention, the sacrificial layer includes a stop layer. In some of the embodiments of the present invention, to sequentially remove the substrate, the sacrificial layer, and a portion of the first conductive layer, remove the substrate, stop at the stop layer, remove the remainder of the sacrificial layer, stop at the first conductive layer, And a portion of the first conductive layer is removed to expose an end of each of the plurality of channel structures.

In some of the embodiments of the present invention, the N-type doped semiconductor layer includes polysilicon, and the dielectric stack layer includes alternating stacked dielectric layers and stacked sacrificial layers. In some of the embodiments of the invention, to replace the dielectric stack with the storage stack, an opening extending vertically through the dielectric stack, stopping at the N-type doped semiconductor layer, is etched, and through the opening, using The stacked conductive layer replaces the stacked sacrificial layer to form a storage stack including interleaved stacked dielectric layers and stacked conductive layers.

In some of these embodiments of the invention, after replacing the dielectric stack layer with the storage stack layer, one or more dielectric materials are deposited into the openings to form insulating structures extending vertically through the storage stack layer.

In some of the embodiments of the present invention, after forming the conductive layer, a source contact is formed in contact with the N-type doped semiconductor layer.

In some of the embodiments of the invention, the interconnect layer is formed in contact with the source electrode, and the contact is formed through the N-type doped semiconductor layer and in contact with the interconnect layer such that the N-type doped semiconductor layer penetrates the source electrode The contact and interconnect layers are electrically connected to the contact.

According to another aspect of the present disclosure, a method for forming a 3D memory element is disclosed. Peripheral circuits are formed on the first substrate. A plurality of channel structures are formed each extending vertically through the storage stack layer and the N-type doped semiconductor layer over the second substrate. The first substrate and the second substrate are bonded face-to-face such that the memory stack is over the peripheral circuitry. The second substrate is removed to expose the upper end of each of the plurality of channel structures and the N-type doped semiconductor layer. A conductive layer formed on the N-type doped semiconductor layer and in contact with upper ends of the plurality of channel structures.

In some of the embodiments of the present invention, to form the plurality of channel structures, a dielectric stack is formed on the N-type doped semiconductor layer, forming a dielectric stack that each extends vertically through the dielectric stack layer and the N-type doped semiconductor layer. Multiple channel structures and replace the dielectric stack with a storage stack.

In some of the embodiments of the present invention, to form the plurality of channel structures, a plurality of channel holes each extending vertically through the dielectric stack layer and the N-type doped semiconductor layer are etched, and along the plurality of channel holes A storage film and a semiconductor channel are sequentially deposited on the sidewalls of each via hole.

In some of these embodiments of the invention, to form the conductive layer, a portion of the storage film adjacent to the N-type doped semiconductor layer is etched to form a recess surrounding a portion of the semiconductor channel and the portion of the semiconductor channel is doped.

In some of the embodiments of the invention, to form the conductive layer, a metal silicide layer is formed in the recess in contact with the doped portion of the semiconductor channel and in contact with the N-type doped semiconductor layer outside the recess, and is formed in the recess Metal layer on metal silicide layer.

In some of these embodiments of the present invention, to form the conductive layer, doped polysilicon is deposited into the recess to make contact with the doped portion of the semiconductor channel, forming metal in contact with the doped polysilicon and the N-type doped semiconductor layer A silicide layer, and a metal layer formed on the metal silicide layer.

In some of the embodiments of the invention, to form the conductive layer, a metal is formed in the recess in contact with the doped portion of the semiconductor channel and on the metal silicide layer on the N-type doped semiconductor layer outside the recess Floor.

In some of the embodiments of the invention, prior to bonding the first substrate and the second substrate, an insulating structure is formed extending vertically through the storage stack.

In some of the embodiments of the present invention, after forming the conductive layer, a source contact is formed over the storage stack layer and in contact with the N-type doped semiconductor layer.

In some of these embodiments of the invention, an interconnect layer is formed over and in contact with the source contact, and a contact is formed through the N-type doped semiconductor layer and in contact with the interconnect layer such that the N-type doped semiconductor layer is formed The hetero semiconductor layer is electrically connected to the contact through the source contact and the interconnect layer.

In some of these embodiments of the invention, the bonding comprises hybrid bonding.

According to one aspect of the present disclosure, a method for forming a three-dimensional (3D) memory element is disclosed, comprising: sequentially forming a sacrificial layer on a substrate, a first stop layer on the sacrificial layer, an N-type doped semiconductor layer on the first stop layer, and a dielectric stack layer on the N-type doped semiconductor layer, formed to respectively extend vertically through the dielectric stack layer and the N-type type doped semiconductor layer, and a plurality of channel structures stopped at the first stop layer, the dielectric stack layer is replaced with a storage stack layer such that each channel structure of the plurality of channel structures extends vertically sequentially removing the substrate, the sacrificial layer and the first stop layer through the storage stack layer and the N-type doped semiconductor layer to expose one end of each channel structure of the plurality of channel structures portion, and a conductive layer is formed in contact with the end portions of the plurality of channel structures.

In some of the embodiments of the present invention, the conductive layer includes a metal silicide layer in contact with the ends of the plurality of channel structures and the N-type doped semiconductor layer, and in contact with the N-type doped semiconductor layer. A metal layer in contact with the metal silicide layer.

In some of the embodiments of the present invention, forming the plurality of channel structures includes etching each extending vertically through the dielectric stack layer and the N-type doped semiconductor layer and at the first stop layer stop at the stop to form a plurality of via holes, and deposit a storage film and a semiconductor channel in sequence along a sidewall of each of the plurality of via holes.

In some of the embodiments of the present invention, forming the conductive layer includes etching a portion of the storage film adjacent to the N-type doped semiconductor layer to form a recess surrounding a portion of the semiconductor channel, and The portion of the semiconductor channel is doped.

In some of the embodiments of the present invention, forming the conductive layer further comprises: forming the metal silicide layer, wherein the metal silicide layer contacts a doped portion of the semiconductor channel in the recessed portion and the metal silicide layer is in contact with the N-type doped semiconductor layer at an outer portion of the recess.

In some of the embodiments of the present invention, forming the conductive layer further includes depositing a doped polysilicon into the recess to contact a doped portion of the semiconductor channel, and forming the silicide and wherein the metal silicide layer is in contact with the doped polysilicon and the N-type doped semiconductor layer.

In some embodiments of the present invention, the sacrificial layer includes a second stop layer, and sequentially removing the substrate, the sacrificial layer and the first stop layer includes: removing the substrate, and in the first stop layer Stopping at the second stop layer, and removing the remainder of the sacrificial layer, stopping at the first stop layer.

In some embodiments of the present invention, the N-type doped semiconductor layer includes a polysilicon, the dielectric stack layer includes a plurality of stacked dielectric layers and a plurality of stacked sacrificial layers, and the storage stack is utilized Layer replacement of the dielectric stack layer includes etching extending vertically through the dielectric stack layer and stopping at the N-type doped semiconductor layer to form a plurality of openings, and through the plurality of openings , replacing the stacked sacrificial layer with a stacked conductive layer to form the storage stack including a plurality of the stacked dielectric layers and a plurality of the stacked conductive layers interleaved.

In some of the embodiments of the present invention, further comprising: after replacing the dielectric stack layer with the storage stack layer, depositing one or more dielectric materials into the opening to form vertically extending through an insulating structure of the storage stack.

In some of the embodiments of the present invention, the method further includes: after forming the conductive layer, forming a source contact in contact with the N-type doped semiconductor layer.

In some of the embodiments of the present invention, further comprising: forming an interconnect layer in contact with the source contact, and forming an interconnect layer through the N-type doped semiconductor layer and in contact with the interconnect layer contact such that the N-type doped semiconductor layer is electrically connected to the contact through the source contact and the interconnect layer.

In some of the embodiments of the present invention, the first stop layer includes a high-k dielectric material.

According to one aspect of the present disclosure, a method for forming a three-dimensional (3D) memory element is disclosed, comprising: sequentially forming a sacrificial layer on a substrate, a first conductive layer on the sacrificial layer, An N-type doped semiconductor layer on the first conductive layer, and a dielectric stack layer on the N-type doped semiconductor layer are formed to each extend vertically through the dielectric stack layer and the dielectric stack layer. the N-type doped semiconductor layer and the plurality of channel structures stopped at the first conductive layer, the dielectric stack layer is replaced with a storage stack layer, so that each channel structure in the plurality of channel structures is vertical extending through the storage stack layer and the N-type doped semiconductor layer, sequentially removing the substrate, the sacrificial layer, and a portion of the first conductive layer to expose the plurality of channel structures One end of each channel structure, and a second conductive layer formed in contact with the ends of the plurality of channel structures and the first conductive layer.

In some embodiments of the present invention, the first conductive layer includes a metal silicide, and the second conductive layer includes a metal.

In some of the embodiments of the present invention, forming the plurality of channel structures includes etching each extending vertically through the dielectric stack layer and the N-type doped semiconductor layer and at the first conductive layer stop at the stop to form a plurality of via holes, and deposit a storage film and a semiconductor channel in sequence along a sidewall of each of the plurality of via holes.

In some of the embodiments of the present invention, forming the second conductive layer includes etching a portion of the storage film adjacent to the N-type doped semiconductor layer to form a recess surrounding a portion of the semiconductor channel, doping the portion of the semiconductor channel and depositing the metal into the recess to contact the doped portion of the semiconductor channel and depositing the metal to an exterior of the recess to in contact with the first conductive layer.

In some embodiments of the present invention, the sacrificial layer includes a stop layer, and sequentially removing the substrate, the sacrificial layer, and the portion of the first conductive layer includes removing the substrate, stopping at the stop layer, removing a remaining portion of the sacrificial layer, stopping at the first conductive layer, and removing a portion of the first conductive layer to expose individual channels in the plurality of channel structures the end of the structure.

In some of the embodiments of the present invention, the N-type doped semiconductor layer includes a polysilicon, the dielectric stack layer includes a plurality of stacked dielectric layers and a plurality of stacked sacrificial layers interleaved, and the storage stack is utilized Layer replacement of the dielectric stack layer includes etching extending vertically through the dielectric stack layer, stopping at the N-type doped semiconductor layer to form a plurality of openings, and passing through the plurality of openings, The stacked sacrificial layer is replaced with a plurality of stacked conductive layers to form the storage stack including the stacked dielectric layers and the stacked conductive layers interleaved.

In some of the embodiments of the present invention, the method further includes: after forming the conductive layer, forming a source contact in contact with the N-type doped semiconductor layer.

According to one aspect of the present disclosure, a method for forming a three-dimensional (3D) memory device is disclosed, comprising: forming a peripheral circuit on a first substrate, forming peripheral circuits each extending vertically through a second substrate a plurality of channel structures of a storage stack layer and an N-type doped semiconductor layer, bonding the first substrate and the second substrate in a face-to-face manner so that the storage stack layer is above the peripheral circuit, removing the second substrate to expose an upper end of each channel structure in the plurality of channel structures and the N-type doped semiconductor layer, and to form a position on the N-type doped semiconductor layer and to be connected to the N-type doped semiconductor layer. a conductive layer contacting the upper ends of the plurality of channel structures.

The foregoing descriptions of specific embodiments will so disclose the general nature of this disclosure that others may readily modify and/or adapt these specific embodiments without undue experimentation by applying knowledge within the skill in the art various applications without departing from the general concept of the present disclosure. Therefore, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein. It is to be understood that the phraseology or terminology herein is for the purpose of description and not limitation so that the terms or phraseology of this specification will be interpreted by one of ordinary skill in the art based on teaching and guidance.

Embodiments of the present disclosure have been described above with the aid of functional building blocks that illustrate the implementation of specified functions and relationships thereof. For the convenience of description, the boundaries of these functional building blocks are arbitrarily defined herein. Alternate boundaries may be defined so long as the specified functions and relationships are appropriately performed.

The Summary and Abstract sections may set forth one or more, but not all, exemplary embodiments of the present disclosure contemplated by the inventors, and, therefore, are not intended to limit the present disclosure and all of it in any way. The attached patent application scope.

The breadth and scope of this disclosure should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the scope of the claims that follow and their equivalents. The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

100: Three-dimensional memory device 101: Substrate 102: First semiconductor structure 104: Second Semiconductor Structure 106: Bonding interface 108: Peripheral circuit 110: Bonding layer 111: Bonded Contacts 112: Bonding layer 113: Bonding Contact 114: Storage Stacked Layers 116: Conductive layer 118: Dielectric layer 120: N-type doped semiconductor layer 121: metal silicide layer 122: Conductive layer 123: metal layer 124: Channel Structure 125: Channel Plug 126: Storage film 127: Top Section 128: Semiconductor channel 129: Channel Plug 130: Insulation structure 132: source contact 133: Interconnect layer 134: Interlayer dielectric layer 136: Rewiring layer 138: Passivation layer 140: Contact pad 142: Contact 144: Contact 146: Peripheral Contact 148: Peripheral Contact 150: Local Contact 152: Word line local contact 155: Stereo Memory Components 160: Stereo memory cell 200: 3D memory device 201: Substrate 202: First semiconductor structure 204: Second Semiconductor Structure 206: Bonding interface 208: Peripheral circuits 210: Bonding Layer 211: Bonded Contacts 212: Bonding Layer 213: Bond Contact 214: Storage Stacked Layers 216: Conductive layer 218: Dielectric layer 219: Metal silicide layer 220: P-type doped semiconductor layer 221: N well 222: Conductive layer 223: metal layer 224: Channel Structure 225: Channel Plug 226: Storage Film 227: Channel Plug 228: Semiconductor channel 229: Top Section 230: Insulation structure 231: source contact 232: source contact 233: Interconnect layer 234: interlayer dielectric layer 236: Redistribution layer 236-1: First Interconnect 236-2: First Interconnect 238: Passivation layer 240: Contact pad 242: Contact 243: Contact 244: Contact 246: Peripheral Contact 247: Perimeter Contact 248: Perimeter Contact 250: Channel local contact 252: Word line local contact 255: Stereo Memory 260: Stereo Memory 302: Carrier substrate 303: Sacrificial Layer 304: stop layer 305: Stop Layer 306: N-type doped semiconductor layer 308: Dielectric stack layer 310: Stacked Dielectric Layers 312: Stacked Sacrificial Layers 314: Channel Structure 315: Tunneling Layer 316: Storage Layer 317: Barrier 318: Semiconductor channel 328: Stacked Conductive Layers 320: Gap 322: Lateral recess 330: Storage Stacked Layers 332: gate dielectric layer 334: Channel local contact 336: Insulation structure 338: Peripheral Contact 340: Peripheral Contact 342: Word line local contact 344: Channel local contact 346: Bonding Layer 348: Bonding Layer 350: Silicon substrate 352: Peripheral circuit 354: Bonding interface 356: Interlayer dielectric layer 357: Recess 358: Source Contact Opening 359: Conductive layer 360: metal silicide layer 361: Contact opening 362: Metal Layer 363: Contact opening 364: source contact 365: Channel Plug 366: Contact 367: Spacer 368: Contact 370: Redistribution layer 372: Passivation layer 374: Contact Pad 376: Interconnect Layer 402: Carrier Substrate 403: Sacrificial Layer 404: stop layer 405: stop layer 406: P-type doped semiconductor layer 407: N well 408: Dielectric stack layer 410: Stacked Dielectric Layers 412: Stacked Sacrificial Layers 414: Channel Structure 415: Tunneling Layer 416: Storage Layer 417: Barrier 418: Semiconductor channel 420: Gap 422: Transverse recess 428: Stacked Conductive Layers 430: Storage Stacked Layers 432: gate dielectric layer 434: Dielectric capping layer 436: Insulation structure 438: Perimeter Contact 439: Perimeter Contact 440: Perimeter Contact 442: Word line local contact 444: Channel local contact 446: Bonding Layer 448: Bonding Layer 450: Silicon substrate 452: Peripheral circuit 454: Bonding interface 456: Interlayer dielectric layer 457: Recess 458: Source Contact Opening 459: Conductive layer 460: Contact opening 461: Contact opening 462: Spacer 463: Contact opening 464: source contact 465: Source Contact Opening 466: Contact 468: Contact 469: Contact 470: Redistribution layer 470-1: First Interconnect 470-2: Second Interconnect 472: Passivation layer 474: Contact Pad 476: metal silicide layer 477: Interconnect Layer 478: Metal Layer 479: Source Contact 480: Channel Plug 500: Method 501: Method 502: Operation steps 504: Operation steps 505: Operation steps 506: Operation steps 507: Operation steps 508: Operation steps 510: Operation steps 512: Operation steps 514: Operation steps 515: Operation steps 516: Operation steps 517: Operation steps 518: Operation steps 520: Operation steps 600: Method 601: Method 602: Operation steps 604: Operation steps 605: Operation steps 606: Operation steps 607: Operation steps 608: Operation steps 610: Operation steps 612: Operation steps 614: Operation steps 615: Operation steps 616: Operation steps 617: Operation steps 618: Operation steps 620: Operation steps

The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate embodiments of the present disclosure and, together with the description, further serve to explain the principles of the present disclosure and to enable those skilled in the relevant art to make and use the present disclosure. 1A shows a side view of a cross-section of an exemplary 3D memory element in accordance with some embodiments of the present disclosure. 1B illustrates a side view of a cross-section of another exemplary 3D memory element in accordance with some embodiments of the present disclosure. 1C shows a side view of a cross-section of yet another exemplary 3D memory element in accordance with some embodiments of the present disclosure. 2A illustrates a side view of a cross-section of yet another exemplary 3D memory element in accordance with some embodiments of the present disclosure. 2B illustrates a side view of a cross-section of yet another exemplary 3D memory element in accordance with some embodiments of the present disclosure. 2C illustrates a side view of a cross-section of yet another exemplary 3D memory element in accordance with some embodiments of the present disclosure. 3A-3P illustrate a manufacturing process for forming an exemplary 3D memory element according to some embodiments of this disclosure. 4A-4Q illustrate a fabrication process for forming another exemplary 3D memory element in accordance with some embodiments of this disclosure. 5A shows a flowchart of a method for forming an exemplary 3D memory element, according to some embodiments of this disclosure. 5B illustrates a flow diagram of another method for forming an exemplary 3D memory element in accordance with some embodiments of this disclosure. 6A shows a flowchart of a method for forming another exemplary 3D memory element, according to some embodiments of this disclosure. 6B illustrates a flowchart of another method for forming another exemplary 3D memory element in accordance with some embodiments of this disclosure. Embodiments of the present disclosure will be described with reference to the accompanying drawings.

100: Three-dimensional memory device

101: Substrate

102: First semiconductor structure

104: Second Semiconductor Structure

106: Bonding interface

108: Peripheral circuit

110: Bonding layer

111: Bonded Contacts

112: Bonding layer

113: Bonding Contact

114: Storage Stacked Layers

116: Conductive layer

118: Dielectric layer

120: N-type doped semiconductor layer

121: metal silicide layer

122: Conductive layer

123: metal layer

124: Channel Structure

126: Storage film

127: Top Section

128: Semiconductor channel

129: Channel Plug

130: Insulation structure

132: source contact

133: Interconnect layer

134: Interlayer dielectric layer

136: Rewiring layer

138: Passivation layer

140: Contact pad

142: Contact

144: Contact

146: Peripheral Contact

148: Peripheral Contact

150: Local Contact

152: Word line local contact

Claims (20)

A method for forming a three-dimensional (3D) memory element, comprising: sequentially forming a sacrificial layer on a substrate, a first stop layer on the sacrificial layer, an N-type doped semiconductor layer on the first stop layer, and the N-type doped semiconductor layer a dielectric stack layer on; forming a plurality of channel structures each extending vertically through the dielectric stack layer and the N-type doped semiconductor layer and stopping at the first stop layer; replacing the dielectric stack with a storage stack such that each channel structure of the plurality of channel structures extends vertically through the storage stack and the N-type doped semiconductor layer; sequentially removing the substrate, the sacrificial layer, and the first stop layer to expose an end of each of the plurality of channel structures; and A conductive layer is formed in contact with the ends of the plurality of channel structures. The method according to claim 1, wherein the conductive layer comprises: a metal silicide layer in contact with the ends of the plurality of channel structures and the N-type doped semiconductor layer; and a metal layer in contact with the metal silicide layer. The method of claim 2, wherein forming the plurality of channel structures comprises: etchings each extend vertically through the dielectric stack layer and the N-type doped semiconductor layer and stop at the first stop layer to form a plurality of via holes; and A storage film and a semiconductor channel are sequentially deposited along one sidewall of each of the plurality of channel holes. The method of claim 3, wherein forming the conductive layer comprises: etching a portion of the storage film adjacent to the N-type doped semiconductor layer to form a recess surrounding a portion of the semiconductor channel; and The portion of the semiconductor channel is doped. The method of claim 4, wherein forming the conductive layer further comprises: forming the metal silicide layer, wherein the metal silicide layer is in the recess with a doped portion of the semiconductor channel contact, and the metal silicide layer is in contact with the N-type doped semiconductor layer at an outer portion of the recess. The method according to claim 4, wherein forming the conductive layer further comprises: depositing a doped polysilicon into the recess to contact a doped portion of the semiconductor channel; and The metal silicide layer is formed, wherein the metal silicide layer is in contact with the doped polysilicon and the N-type doped semiconductor layer. The method of claim 1, wherein the sacrificial layer includes a second stop layer, and sequentially removing the substrate, the sacrificial layer and the first stop layer includes: removing the substrate, stopping at the second stop layer; and The remainder of the sacrificial layer is removed, stopping at the first stop layer. The method of claim 1, wherein the N-type doped semiconductor layer includes a polysilicon, the dielectric stack layer includes a plurality of stacked dielectric layers and a plurality of stacked sacrificial layers that are interleaved, and utilizing the storage Stacking layers replacing the dielectric stacking layers include: etching extending vertically through the dielectric stack and stopping at the N-type doped semiconductor layer to form a plurality of openings; and The stacked sacrificial layer is replaced with a stacked conductive layer through the plurality of openings to form the storage stack including a staggered plurality of the stacked dielectric layers and a plurality of the stacked conductive layers. The method of claim 8, further comprising: after replacing the dielectric stack layer with the storage stack layer, depositing one or more dielectric materials into the opening to form vertically extending through the dielectric stack layer. An insulating structure of the storage stack layer is described. The method of claim 1, further comprising: after forming the conductive layer, forming a source contact in contact with the N-type doped semiconductor layer. The method according to claim 10, further comprising: forming an interconnect layer in contact with the source contact; and forming a contact through the N-type doped semiconductor layer and in contact with the interconnect layer such that the N-type doped semiconductor layer is electrically connected to all of the N-type doped semiconductor layers through the source contact and the interconnect layer mentioned contact. The method of claim 1, wherein the first stop layer comprises a high-k dielectric material. A method for forming a three-dimensional (3D) memory element, comprising: A sacrificial layer on a substrate, a first conductive layer on the sacrificial layer, an N-type doped semiconductor layer on the first conductive layer, and an N-type doped semiconductor layer are formed in sequence a dielectric stack on the layer; forming a plurality of channel structures each extending vertically through the dielectric stack layer and the N-type doped semiconductor layer and stopping at the first conductive layer; replacing the dielectric stack with a storage stack such that each channel structure of the plurality of channel structures extends vertically through the storage stack and the N-type doped semiconductor layer; sequentially removing the substrate, the sacrificial layer, and a portion of the first conductive layer to expose one end of each of the plurality of channel structures; and A second conductive layer is formed in contact with the ends of the plurality of channel structures and the first conductive layer. The method of claim 13, wherein the first conductive layer comprises a metal silicide and the second conductive layer comprises a metal. The method of claim 14, wherein forming the plurality of channel structures comprises: etchings each extend vertically through the dielectric stack layer and the N-type doped semiconductor layer and stop at the first conductive layer to form a plurality of via holes; and A storage film and a semiconductor channel are sequentially deposited along one sidewall of each of the plurality of channel holes. The method of claim 15, wherein forming the second conductive layer comprises: etching a portion of the storage film adjacent to the N-type doped semiconductor layer to form a recess surrounding a portion of the semiconductor channel; doping the portion of the semiconductor channel; and The metal is deposited into the recess to contact the doped portion of the semiconductor channel, and the metal is deposited to an exterior of the recess to contact the first conductive layer. The method of claim 13, wherein the sacrificial layer includes a stop layer, and sequentially removing the substrate, the sacrificial layer, and the portion of the first conductive layer includes: removing the substrate, stopping at the stop layer; removing a remaining portion of the sacrificial layer, stopping at the first conductive layer; and A portion of the first conductive layer is removed to expose the end of each channel structure of the plurality of channel structures. The method of claim 13, wherein the N-type doped semiconductor layer includes a polysilicon, the dielectric stack layer includes a plurality of stacked dielectric layers and a plurality of stacked sacrificial layers that are interleaved, and wherein the storage Stacking layers replacing the dielectric stacking layers include: etching extending vertically through the dielectric stack layer, stopping at the N-type doped semiconductor layer to form a plurality of openings; and The stacked sacrificial layer is replaced with a plurality of stacked conductive layers through the plurality of openings to form the storage stack including the stacked dielectric layers and the stacked conductive layers interleaved. The method of claim 13, further comprising: after forming the conductive layer, forming a source contact in contact with the N-type doped semiconductor layer. A method for forming a three-dimensional (3D) memory element, comprising: forming a peripheral circuit on a first substrate; forming a plurality of channel structures each extending vertically through a storage stack layer and an N-type doped semiconductor layer over a second substrate; bonding the first substrate and the second substrate face-to-face such that the memory stack is over the peripheral circuit; removing the second substrate to expose an upper end of each of the plurality of channel structures and the N-type doped semiconductor layer; and A conductive layer is formed on the N-type doped semiconductor layer and in contact with the upper ends of the plurality of channel structures.

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