TW202115827A - Selective and self-limiting tungsten etch process - Google Patents

Abstract

Methods of dep-etch in semiconductor devices (e.g. V-NAND) are described. A metal layer is deposited in a feature. The metal layer is removed by low temperature atomic layer etching by oxidizing the surface of the metal layer and etching the oxide in a layer-by-layer fashion. After removal of the metal layer, the features are filled with a metal.

Description

Selective and self-limiting tungsten etching process

The embodiments of this disclosure generally relate to methods of filling gaps or features in semiconductor devices. More specifically, the embodiment of the present disclosure relates to a method of gap filling in a three-dimensional semiconductor device using tungsten.

As the design of semiconductor devices and the complexity of material components continue to increase, the selective removal of materials has become critical to the continued scale and improvement of semiconductor devices. Selective atomic layer etching (ALE) has become a precision etching method that uses self-limiting surface reactions. The selective ALE of metal oxide (MO _x ) is particularly important for many semiconductor technologies, but due to the inherent stability of these oxide materials, it may be difficult to achieve.

The V-NAND (or 3D-NAND) structure is used in flash memory applications. A V-NAND device is a vertically stacked NAND structure with a large number of cells arranged in blocks. The back gate word line formation is the mainstream processing flow in the current 3D-NAND manufacturing. Before forming the word line, the substrate is a layered oxide stack supported by the memory string. The interstitial space is filled with tungsten using CVD or ALD. The top/sidewalls of the memory stack are also coated with tungsten. The tungsten is removed from the top/sidewall of the stack by an etching process (eg, reactive ion etching (RIE) process or radical-based etching process), so that tungsten exists only on the inner side of the interstitial space, and each tungsten filler and others The tungsten filler is completely separated. However, due to the loading effect of the etching process, the separation etching usually results in a different word line recess at the top of the stack than at the bottom. As the stack of oxide layers increases, this difference becomes more pronounced.

In the multi-layer VNAND tungsten filling, filling tungsten presents challenges, especially in the buried world line. The deposition-etch cycle technology is being sought to produce better gap filling. However, currently, there is no cyclic deposition-etching process that can produce effective tungsten gap filling.

Therefore, there is a need for improved methods of etching tungsten, especially in NAND applications.

One or more embodiments of the present disclosure relate to a method of processing a substrate. In one or more embodiments, a processing method includes the steps of: depositing a metal layer in at least one feature on a substrate; oxidizing the metal to a first depth to form a metal oxide layer on the metal layer; and etching the metal oxide The material layer is used to selectively remove the metal oxide layer.

Other embodiments of this disclosure relate to methods of processing substrates. In one or more embodiments, a processing method includes the following steps: depositing a metal layer on a substrate surface, the substrate surface has at least one feature, at least one feature extends the depth of the feature from the substrate surface to the bottom surface, and at least one feature has The width defined by the first sidewall and the second sidewall, wherein the metal layer is deposited on the substrate surface, the first sidewall, the second sidewall, and the bottom surface of at least one feature; and the processing cycle is performed, including the steps of: oxidizing the metal to the second A depth to form a metal oxide layer on the metal layer; and etching the metal oxide layer to selectively remove the metal oxide layer.

A further embodiment of the present disclosure relates to a method of processing a substrate. In one or more embodiments, a method of processing a substrate includes the following steps: forming a film stack on the substrate, the film stack including a plurality of alternating layers of oxide materials and nitride materials, and the film stack having a stack thickness; The top of the film stack surface extends a depth of opening to the bottom surface, the opening has a width defined by the first side wall and the second side wall; optionally on the film stack surface and on the first side wall, second side wall, and bottom surface of the opening A barrier layer is formed, the barrier layer includes TiN with a thickness in the range of about 20 Å to about 50 Å; a metal layer is deposited on the film stack so that the metal layer fills the opening and covers the top of the film stack with the thickness of the metal layer; and repeatedly oxidize The surface of the metal layer is formed to form a metal oxide layer, and the metal oxide layer is etched from at least one feature until the metal layer is removed. Oxidizing the surface includes the following steps: exposing to O ₂ , and etching the metal oxide includes the following steps: exposing For halide etchant.

Before describing several exemplary embodiments of the present disclosure, it should be understood that the present disclosure is not limited to the details of the configuration or processing steps set forth in the following description. The present disclosure can have other embodiments and can be practiced or executed in various ways.

As used in this specification and the accompanying patent application, the terms "substrate" and "wafer" are used interchangeably, and both refer to the surface or part of the surface on which the treatment acts. Those familiar with the art will also understand that unless the context clearly dictates otherwise, references to the substrate may also refer to only a part of the substrate. In addition, reference to deposition on a substrate may refer to a bare substrate and a substrate on which one or more films or features are deposited or formed.

As used herein, "substrate" refers to any substrate or material surface formed on a substrate on which film processing is performed during a manufacturing process. For example, the substrate surface on which processing can be performed includes materials such as silicon, silicon oxide, strained silicon, silicon-on-insulator (SOI), carbon-doped silicon oxide, amorphous silicon, doped silicon, germanium, gallium arsenide, Materials for glass, sapphire, and any other materials such as metals, metal nitrides, metal alloys, and other conductive materials, depending on the application. The substrate includes (but is not limited to) a semiconductor wafer. The substrate may be exposed to a pre-treatment process for polishing, etching, reduction, oxidation, hydroxylation, annealing, UV curing, electron beam curing, and/or baking the surface of the substrate. In addition to directly performing film processing on the surface of the substrate itself, in this disclosure, any film processing steps disclosed can also be performed on the bottom layer formed on the substrate, as disclosed in more detail below, and the term " "Substrate surface" is intended to include such underlayers as the context dictates. Therefore, for example, in the case where the film/layer or part of the film/layer has been deposited on the surface of the substrate, the exposed surface of the newly deposited film/layer becomes the surface of the substrate.

Semiconductor manufacturing processes generally involve depositing metal (eg, tungsten (W)) into features (such as but not limited to vias or trenches) to form contacts or interconnects. Metals (eg, tungsten (W)) are usually deposited into features using chemical vapor deposition (CVD), in which a substrate with at least one feature to be filled is exposed to a metal-containing precursor and a reducing agent to deposit the metal Into the feature. However, as devices shrink and features become smaller and smaller, filling with CVD is more challenging, especially in advanced logic and memory applications.

One or more embodiments of the present disclosure advantageously provide a method of depositing a tungsten film in the gap of a three-dimensional structure. Some embodiments of the present disclosure advantageously provide methods for depositing conformal tungsten oxide films and selectively removing tungsten oxide. Some embodiments advantageously provide a method of filling the lateral features of the V-NAND with a high-quality tungsten film that has a uniform thickness from the top to the bottom of the oxide stack. In one or more embodiments, the treatment method advantageously does not use plasma. In addition, the processing method of one or more embodiments advantageously selectively removes tungsten at a more controlled rate than other deposition etching techniques.

One or more embodiments of the present disclosure relate to word line separation methods based on highly conformal metal (eg, tungsten) oxidation and highly selective metal oxide (eg, tungsten oxide) removal. The method can use high temperature or low temperature treatment.

One or more embodiments of the present disclosure relate to a deposition-etch ("dep-etch") cycle technique to produce better gap filling. The method of one or more embodiments facilitates this deposition etching cycle process. In addition, in one or more embodiments, because the natural oxide is removed from the surface of the metal (eg, tungsten), the contact resistance of the semiconductor device is improved.

Referring to Figure 1, a substrate 10 has a stack 12 of layers thereon. The substrate 10 may be any suitable substrate material and is not limited to the same material as any single layer. For example, in some embodiments, the substrate is an oxide, nitride, or metal layer. The stack 12 has a plurality of oxide layers 14 spaced apart from each other to form gaps 16 between the oxide layers 14 so that each gap forms a word line or a shell for forming the word line. The stack 12 has a top 13 and a side 15.

The stack 12 may have any suitable number of oxide layers 14 or gaps 16. In some embodiments, there are greater than or equal to about 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100 gaps 16 formed in the stack 12, and the gaps 16 can be used to form an equal number of word lines . The number of gaps 16 is measured on either side of the memory string 11 connecting all the individual oxide layers 14. In some embodiments, the number of gaps 16 is a multiple of two. In some embodiments, the number of gaps is equal to 2 ⁿ , where n is any positive integer. In some embodiments, the number of gaps 16 is about 96.

As shown in FIG. 2, the metal 20 is deposited on the stack 12. The metal 20 fills the gap 16 to form a word line 19. The metal 20 is formed around the stack 12 so that the metal 20 covers the top 13 and the side 15 of the stack 12 with the thickness of the metal covering layer 22. The cover layer 22 is a material deposited on the outside of the gap 16. The capping layer may have any suitable thickness, depending on the process used to deposit the metal 20. In some embodiments, the thickness of the cover layer 22 is in the range of about 1 Å to 1000 Å. In some embodiments, the thickness of the cover layer 22 is greater than or equal to about 5Å, 10Å, 15Å, 20Å, 25Å, 30Å, 35Å, 40Å, 45Å, or 50Å.

The metal 20 can be any suitable metal used in word line applications. In some embodiments, the metal film includes tungsten. In some embodiments, the metal film does not contain tungsten. In some embodiments, the metal film consists essentially of tungsten. As used in this respect, the term "consisting essentially of tungsten" means that the composition of the bulk metal film is greater than or equal to about 95%, 98%, or 99% tungsten on an atomic basis. The main metal film excludes the part of the metal 20 that may be in contact with another surface (such as an oxide surface) or open for further processing, because these areas may have a small amount of atomic diffusion with adjacent materials or have similar hydride-terminated Some surface functional groups (moiety).

The metal 20 can be deposited by any suitable technique, including but not limited to chemical vapor deposition (CVD) or atomic layer deposition (ALD). The metal 20 is deposited on the inside of the gap space and at the top/sidewall of the memory stack.

Referring to Figures 3A and 3B, high temperature oxidation with low temperature etching treatment is shown. In FIG. 3A, the metal 20 is oxidized into a metal oxide 25 to a depth of about the thickness of the cover layer 22. Almost all of the covering layer 22 can be oxidized in one step of oxidation treatment. The oxidation of the cover layer may be affected by, for example, the oxidation gas flow, the partial pressure of the oxidation gas, the temperature of the wafer, and the processing time to form a highly conformal oxidation of the metal cover layer 22.

The oxidizing gas may be any suitable oxidizing gas that can react with the metal 20 that has been deposited. Suitable oxidizing gases include (but are not limited to) O ₂ , O ₃ , H ₂ O, H ₂ O ₂ , NO, NO ₂ or combinations thereof. In some embodiments, the oxidizing gas includes one or more of _{O 2} or O _3. In some embodiments, the oxidizing gas consists essentially of one or more of _{O 2} or O _3. When used in this way, the term "consisting essentially of" means that the oxidizing component of the oxidizing gas is greater than or equal to about 95%, 98%, or 99% of the claimed species. The oxidizing gas may include inert gas, diluent gas, or carrier gas. For example, the oxidizing gas may be co-flowed or diluted with one or more of _{Ar, He, or N 2.}

The metal oxide 25 of some embodiments includes tungsten oxide (WO _x ). In some embodiments, metal oxide 25 is a derivative of metal 20, which may or may not include oxygen. Suitable derivatives of metal films include (but are not limited to) nitrides, borides, carbides, oxynitrides, oxyborides, oxycarbides, carbonitrides, boron carbides, boron nitrides, boron carbonitrides, Boron oxycarbonitride, oxycarbonitride, borooxycarbide and boron oxynitride. Those skilled in the art will understand that the deposited metal film and the metal film may have non-stoichiometric atoms. For example, a film designated as WO may have different amounts of tungsten and oxygen. The WO film may be, for example, 90 atomic% tungsten. The use of WO to describe a tungsten oxide film means that the film contains tungsten and oxygen atoms, and should not be regarded as limiting the film to a specific composition. In some embodiments, the film consists essentially of designated atoms. For example, a film substantially composed of WO means that the composition of the film is greater than or equal to about 95%, 98%, or 99% of tungsten and oxygen atoms.

In the treatment shown in Figures 3A and 3B, the oxidation treatment takes place at a high temperature. As used in this regard, the term "high temperature" refers to a temperature greater than or equal to 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, or 850°C. In some embodiments, the temperature of the oxidation treatment is in the range of about 400°C to about 950°C, or in the range of about 450°C to about 900°C, or in the range of about 500°C to about 850°C.

The pressure during the oxidation treatment may be in the range of about 0.1 Torr to about 760 Torr. The treatment time (exposure time) can be in the range of about 0.1 seconds to 12 hours. The temperature during the oxidation treatment affects the pressure and treatment time.

In some embodiments, the metal 20 of the capping layer 22 is oxidized to form a metal oxide 25 on the top 13 and side 15 of the stack 12 while leaving the metal 20 in the gap 16 to form the word line 19. In some embodiments, substantially all of the metal 20 in the gap 16 remains after oxidation. When used in this manner, the term “substantially all” means that the metal 20 is oxidized to within ±1 Å of the side 15 of the stack 12.

Referring to FIG. 3B, the metal oxide 25 formed of the cover layer 22 is etched from the top 13 and the side 15 of the stack 12 to leave the metal 20 in the gap 14 as a word line 19. The etching process of some embodiments is a selective etching process, which will remove the metal oxide 25 without substantially affecting the metal 20.

In some embodiments, the etchant includes a metal halide etchant. The etchant of some embodiments consists essentially of a metal halide etchant. When used in this way, the term "consisting essentially of metal halide etchant" means that the specified metal halide etchant species constitute 95%, 98%, or 99% of the total metal halide etchant species (excluding inert Gas, diluent gas or carrier gas). The metal halide etchant may have the same metal species as the metal oxide 25 or a different metal species. In some embodiments, the metal halide etchant includes the same metal species as the metal oxide 25.

In some embodiments, the metal halide etchant contains halogen atoms consisting essentially of chlorine. When used in this manner, the term "consisting essentially of chlorine" means that chlorine constitutes greater than or equal to about 95%, 98%, or 99% of the halogen atoms in the metal halide etchant on an atomic basis. In some embodiments, the metal halide etchant contains halogen atoms consisting essentially of fluorine. When used in this manner, the term "consisting essentially of fluorine" means that fluorine constitutes greater than or equal to about 95%, 98%, or 99% of the halogen atoms in the metal halide etchant on an atomic basis.

In some embodiments, the metal halide etchant includes one or more of _{WF 6} , WCl ₅ , WCl _{6 or tungsten oxyhalide.} In some embodiments, the metal halide etchant consists essentially of one or more of _{WF 6} , WCl ₅ or WCl _6. When used in this manner, the term "consisting essentially of" means that the claimed species constitutes greater than or equal to about 95%, 98%, or 99% of the metal halide on a molar basis.

The etching temperature of some embodiments is lower than the temperature during oxidation. In some embodiments, the etching temperature is in the range of about 300°C to about 600°C, or in the range of about 400°C to about 500°C. In some embodiments, the etching temperature is less than or equal to about 600°C, 550°C, 500°C, 450°C, 400°C, or 350°C. In some embodiments, the temperature during etching is greater than or equal to about 50°C, 75°C, 100°C, 125°C, or 150°C lower than the temperature during oxidation. In some embodiments, both oxidation and etching occur at a temperature greater than or equal to about 300°C.

After the metal oxide 25 is etched, the metal cap layer 22 is removed, and the metal 20 remaining in the gap 14 as the word line 19 is substantially flush with the side surface 15 of the stack 12. When used in this way, the term “substantially flush” means that the word line 19 in the gap 16 is within ±1 Å of the side 15 of the stack 12.

The examples shown in Figures 3A and 3B show high-temperature oxidation-low-temperature etching treatments. The examples shown in Figs. 4A to 4D show low-temperature oxidation and etching treatments. Some of the differences between treatments include (but are not limited to) lower temperature oxidation and slower cover removal.

After the stack 12 has the metal 20 formed with the cover layer 22 (as shown in FIG. 2), the removal of the cover layer can be performed by an atomic layer etching type process. The atomic layer etching process may include multiple repeated processes, which will modify the surface to be etched and then volatilize or remove the modified surface, thereby exposing the new surface below.

Referring to FIG. 4A, the cover layer 22 is oxidized to form a metal oxide 25 on the surface of the cover layer 22. The oxidation treatment can use the same reactants and parameters as the embodiment shown in Figure 3A, with some changes to allow atomic layer etching (ALE) treatment. The oxidation treatment of some embodiments occurs at a temperature of about 300°C to about 500°C. In some embodiments, oxidation occurs at a temperature less than or equal to about 500°C, 450°C, 400°C, or 350°C. The pressure during the low-temperature oxidation treatment may be in the range of about 0.1 Torr to about 760 Torr. The treatment or exposure time can be in the range of about 0.001 seconds to about 60 seconds. In the atomic layer etching process, each oxidation and etching process is self-limiting, because once it reacts with the active surface site, the process stops. For example, once all the active surface sites of the metal 20 are exposed to the oxidant and react with the oxidant to form a metal oxide 25 film, further oxidation will not easily occur. Similarly, once the etchant has removed the oxide film to expose the fresh metal 20 below, the etchant has no further oxide to remove.

Referring to FIG. 4B, after the metal oxide 25 is formed on the metal 20, the stack 12 is exposed to an etchant. The etchant and etching conditions may be the same as shown and described with respect to FIG. 3B. The metal oxide 25 layer on the metal 20 is thinner than the embodiment shown in FIGS. 3A and 3B, so that the etching process will take less time. In some embodiments, the etchant processing time is in the range of about 0.1 seconds to about 60 seconds.

In some embodiments, the temperature during the oxidation and etching process occurs at a temperature less than or equal to about 400°C. The temperature of the etching process shown in Figure 4B can be the same as that of the oxidation process in Figure 4A, so that the substrate containing the stack 12 can be quickly moved from one processing area of the processing chamber to another processing area of the processing chamber to reduce The substrate is sequentially exposed to oxidation and etching conditions.

This type of ALE processing may be referred to as spatial ALE, in which various reactive gases (eg, oxidizer and etchant) flow into separate areas of the processing chamber, and the substrate moves between the areas. The different processing areas are separated by gas curtains, which contain one or more purifying gas flows and/or vacuum flows to prevent the oxidant and etchant from mixing in the gas phase. ALE processing can also be performed by time-domain processing, in which the processing chamber is filled with an oxidant, purified to remove excess oxidant and reaction products or by-products, filled with etchant, and then purified to remove excess etchant and Reaction products or by-products. In time domain processing, the substrate can remain stationary.

Figures 4C and 4D respectively show repeated exposure to an oxidizer to form a metal oxide 25 and an etchant to remove the metal oxide. Although the process is shown as using two cycles, those skilled in the art will understand that this is only a representation, and more than two cycles can be used to remove the cover layer 22 and leave the metal 20 as the word line 19 in the gap 16 .

In some embodiments, a barrier layer is formed on the oxide layer 14 before the metal 20 is deposited. The barrier layer can be any suitable barrier material. In some embodiments, the barrier layer includes titanium nitride. In some embodiments, the barrier layer consists essentially of titanium nitride. When used in this manner, the term "consisting essentially of titanium nitride" means that the composition of the barrier layer is greater than or equal to about 95%, 98%, or 99% of titanium and nitrogen atoms on an atomic basis. The thickness of the barrier layer can be any suitable thickness. In some embodiments, the thickness of the barrier layer is in the range of about 20 Å to about 50 Å.

Figures 5A-5D show partial cross-sectional views of the substrate 100 with the features 110, and show in detail the atomic layer etching process according to one or more embodiments of the present disclosure. The drawings show a substrate with a single feature for illustration purposes; however, those skilled in the art will understand that there may be more than one feature. The shape of the feature 110 can be any suitable shape, including but not limited to grooves and cylindrical through holes. In this regard, the term "feature" refers to any intentional surface irregularities. Suitable examples of features include, but are not limited to, a trench with a top, two sidewalls, and a bottom, and a peak with a top and two sidewalls. Features can have any suitable aspect ratio (the ratio of the depth of the feature to the width of the feature). In some embodiments, the aspect ratio is greater than or equal to about 5:1, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, or 40:1.

The substrate 100 has a substrate surface 120. At least one feature 110 forms an opening in the substrate surface 120. At least one feature 110 extends from the substrate surface 120 to a feature depth D _f to the bottom surface 112. The at least one feature 110 has a first side wall 114 and a second side wall 116 that define the width W of the at least one feature 110. The opening area formed by the side walls 114, 116 and the bottom 112 is also called a gap. In one or more embodiments, the width W is homogeneous along the depth D1 of the at least one feature 110. In other embodiments, the width (W) at the top of the at least one feature 110 is greater than the width (W) at the bottom surface 112 of the at least one feature 110.

In one or more embodiments, the substrate 100 is a film stack including a plurality of alternating layers of nitride material 104 and oxide material 106 deposited on the semiconductor substrate 102.

The semiconductor substrate 102 can be any suitable substrate material. In one or more embodiments, the semiconductor substrate 102 includes semiconductor materials, such as silicon (Si), carbon (C), germanium (Ge), silicon germanium (SiGe), gallium arsenide (GaAs), indium phosphate (InP ), indium gallium arsenide (InGaAs), aluminum indium arsenide (InAlAs), germanium (Ge), silicon germanium (SiGe), copper indium gallium selenide (CIGS), other semiconductor materials or any combination thereof. In one or more embodiments, the semiconductor substrate 102 includes silicon (Si), germanium (Ge), gallium (Ga), arsenic (As), indium (In), phosphorus (P), copper (Cu), or selenium ( One or more of Se). Although some examples of materials that can form the substrate 102 are described here, they can be used to construct passive and active electronic devices (eg, transistors, memory, capacitors, inductors, resistors, switches, integrated circuits, amplifiers). , Photoelectric devices or any other electronic devices) can fall within the spirit and scope of this disclosure.

In one or more embodiments, at least one feature 110 includes a memory hole or word line slit. Therefore, in one or more embodiments, the substrate 100 includes a memory device or a logic device, such as NAND, V-NAND, DRAM, or the like.

As used herein, the term "3D NAND" refers to an electronic (solid-state) non-volatile computer storage memory in which memory cells are stacked in multiple layers. A 3D NAND memory usually includes a plurality of memory cells, and the plurality of memory cells include floating gate transistors. Traditionally, a 3D NAND memory cell includes a plurality of NAND memory structures arranged in three dimensions around a bit line.

As used herein, the term "Dynamic Random Access Memory" or "DRAM" refers to packets that store charge (ie, binary one) or no charge (ie, binary zero) on a capacitor. A memory unit that stores data bits. The charge is gated on the capacitor through the access transistor, and is induced by turning on the same transistor and looking at the voltage disturbance caused by the dumping of the charge packet on the interconnection line on the output of the transistor. Therefore, a single DRAM cell consists of a transistor and a capacitor.

Referring to FIG. 5B, a metal layer 124 is deposited in at least one feature 110. In one or more embodiments, the metal layer 124 includes one or more of tungsten (W), titanium (Ti), tantalum (Ta), nickel (Ni), cobalt (Co), or molybdenum (Mo). In one or more embodiments, the metal layer 124 includes one or more of tungsten (W). In one or more embodiments, the metal layer 124 is deposited with a capping layer 126. In some embodiments, the conformal liner 122 is deposited in the at least one feature 110 before the metal layer 124 is deposited. The conformal liner 122 may comprise any suitable material known to those skilled in the art. In one or more embodiments, the conformal liner 122 includes one or more of titanium nitride (TiN) or tantalum nitride (TaN).

Referring to FIG. 5C, after the metal layer 124 with the capping layer 126 (and optionally the conformal liner 122) has been deposited, the removal of the capping layer 126 can be performed by an atomic layer etching type process. The atomic layer etching process may include multiple repeated processes, which will modify the surface to be etched, and then volatilize or remove the modified surface, thereby exposing the new surface below.

Referring to FIG. 5C, the capping layer 126 is oxidized to form a metal oxide layer 128 on the surface of the capping layer 126. In one or more embodiments, the metal layer 122 is oxidized to a depth of the metal oxide layer 128 to about the thickness of the cover layer 126. Almost all of the covering layer 126 can be oxidized in one step of oxidation treatment. The oxidation of the cover layer 126 may be affected by, for example, the oxidation gas flow, the partial pressure of the oxidation gas, the wafer temperature and the processing time to form a highly conformal oxidation of the metal cover layer 126.

In one or more embodiments, the oxidizing gas is any suitable oxidizing gas that can react with the metal layer 122 that has already been deposited. Suitable oxidizing gases include (but are not limited to) O ₂ , O ₃ , H ₂ O, H ₂ O ₂ , NO, NO ₂ or combinations thereof. In some embodiments, the oxidizing gas includes one or more of _{O 2} or O _3. In some embodiments, the oxidizing gas consists essentially of one or more of _{O 2} or O _3. When used in this way, the term "consisting essentially of" means that the oxidizing component of the oxidizing gas is greater than or equal to about 95%, 98%, or 99% of the claimed species. The oxidizing gas may include inert gas, diluent gas, or carrier gas. For example, the oxidizing gas may be co-current or diluted with one or more of _{Ar, He, or N 2.}

The metal oxide layer 128 of some embodiments includes tungsten oxide (WO _x ). In some embodiments, the metal oxide layer 128 is a derivative of the metal layer 122, which may or may not include oxygen. Suitable derivatives of the metal layer 122 include (but are not limited to) nitrides, borides, carbides, oxynitrides, oxyborides, oxycarbides, carbonitrides, boron carbides, boron nitrides, boron carbonitrides , Boron oxycarbonitride, oxycarbonitride, borooxycarbide and boron oxynitride. Those skilled in the art will understand that the deposited metal layer 122 and metal film may have non-stoichiometric atoms. For example, the metal layer 122 designated as WO may have different amounts of tungsten and oxygen. The WO film may be, for example, 90 atomic% tungsten. The use of WO to describe a tungsten oxide film means that the film contains tungsten and oxygen atoms, and should not be regarded as limiting the film to a specific composition. In some embodiments, the film consists essentially of designated atoms. For example, a film substantially composed of WO means that the composition of the film is greater than or equal to about 95%, 98%, or 99% of tungsten and oxygen atoms.

In the treatment shown in FIGS. 5A to 5D, the oxidation treatment occurs at a high temperature, so that the oxidation is thermal oxidation or rapid thermal oxidation or spike annealing treatment. In this regard, the term "high temperature" refers to a temperature greater than or equal to about 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, or 850°C. In some embodiments, the temperature of the oxidation treatment is in the range of about 400°C to about 950°C, or in the range of about 450°C to about 900°C, or in the range of about 500°C to about 850°C.

In one or more embodiments, the pressure during the oxidation treatment is in the range of about 0.1 Torr to about 760 Torr. The treatment time (exposure time) can be in the range of about 0.1 seconds to 12 hours. The temperature during the oxidation treatment affects the pressure and treatment time.

In some embodiments, the metal layer 124 of the capping layer 126 is oxidized to form a metal oxide layer 128 on the top 130 and sides 132 of the at least one feature 110 while retaining the metal layer 124 in the at least one feature 110. In some embodiments, substantially all of the metal layer 124 in at least one feature 110 remains after oxidation. When used in this manner, the term “substantially all” means that the metal layer 124 is oxidized to within ±1 Å of the side 132 of at least one feature 110.

Referring to FIG. 5D, the metal oxide layer 128 formed by the capping layer 126 is etched from the top 130 and the side 132 to leave the metal layer 124. The etching process of some embodiments is a selective etching process, which will remove the metal oxide layer 128 without substantially affecting the metal layer 124.

In some embodiments, the etchant includes a metal halide etchant. The etchant of some embodiments consists essentially of a metal halide etchant. When used in this way, the term "consisting essentially of metal halide etchant" means that the specified metal halide etchant species constitute 95%, 98%, or 99% of the total metal halide etchant species (excluding inert Gas, diluent gas or carrier gas). The metal halide etchant may have the same metal species as the metal oxide layer 128 or a different metal species. In some embodiments, the metal halide etchant includes the same metal species as the metal oxide layer 128.

In some embodiments, the metal halide etchant contains halogen atoms consisting essentially of chlorine. In other embodiments, the metal halide etchant contains halogen atoms consisting essentially of fluorine. When used in this manner, the term "consisting essentially of fluorine" means that fluorine constitutes greater than or equal to about 95%, 98%, or 99% of the halogen atoms in the metal halide etchant on an atomic basis.

In some embodiments, the metal halide etchant includes one or more of _{WF 6} , WCl ₅ , WCl _{6 or tungsten oxyhalide.} In some embodiments, the metal halide etchant consists essentially of one or more of _{WF 6} , WCl ₅ , WCl _{6 or tungsten oxyhalide.} When used in this manner, the term "consisting essentially of" means that the claimed species constitutes greater than or equal to about 95%, 98%, or 99% of the metal halide on a molar basis.

The etching temperature of some embodiments is lower than the temperature during oxidation. In some embodiments, the etching temperature is in the range of about 100°C to about 600°C, or in the range of about 100°C to about 500°C. In some embodiments, the etching temperature is less than or equal to about 600°C, 550°C, 500°C, 450°C, 400°C, or 350°C. In some embodiments, the temperature during etching is greater than or equal to about 50°C, 75°C, 100°C, 125°C, or 150°C lower than the temperature during oxidation. In some embodiments, etching occurs at about 300°C. In some embodiments, both oxidation and etching occur at a temperature greater than or equal to about 400°C.

The oxidation treatment of some embodiments occurs at a temperature of about 300°C to about 500°C. In some embodiments, oxidation occurs at a temperature less than or equal to about 500°C, 450°C, 400°C, or 350°C. The pressure during the low-temperature oxidation treatment may be in the range of about 0.1 Torr to about 760 Torr. The treatment or exposure time can be in the range of about 0.001 seconds to about 60 seconds. In the atomic layer etching process, each oxidation and etching process is self-limiting, because once it reacts with the active surface site, the process stops. For example, once all active surface sites of the metal layer 124 are exposed to the oxidant and react with the oxidant to form the metal oxide layer 128, further oxidation will not easily occur. Similarly, once the etchant has removed the metal oxide layer 128 to expose the underlying fresh metal layer 124, the etchant has no further oxide to remove.

Referring to FIG. 5D, after the metal oxide layer 128 is formed on the metal layer 124, the substrate 102 is exposed to an etchant. The etchant and etching conditions may be the same as shown and described above. In some embodiments, the etchant processing time is in the range of about 0.1 seconds to about 60 seconds.

In one or more embodiments, this type of ALE processing may be referred to as spatial ALE, in which various reactive gases (eg, oxidizer and etchant) flow into separate areas of the processing chamber, and the substrate is between the areas mobile. The different processing areas are separated by gas curtains, which contain one or more purifying gas flows and/or vacuum flows to prevent the oxidant and etchant from mixing in the gas phase. ALE processing can also be performed by time-domain processing, in which the processing chamber is filled with an oxidant, purified to remove excess oxidant and reaction products or by-products, filled with etchant, and then purified to remove excess etchant and Reaction products or by-products. In time domain processing, the substrate can remain stationary

After etching the metal oxide 128, the process is repeated-the metal layer 124 is oxidized to form the metal oxide layer 128, which is then etched to remove the oxide layer. Although this process is shown as using a single cycle, those skilled in the art will understand that this is only a representation, and more than two cycles may be used to remove the metal layer 124. In one or more embodiments, the processing is repeated n processing cycles. In one or more embodiments, n is a number in the range of about 2 to about 2,000. In other embodiments, n is a number greater than about 10, greater than about 25, greater than about 50, greater than about 75, or greater than about 100.

As shown in FIG. 5D, the processing is completed in a layer-by-layer method until the metal layer 124 is selectively removed from the at least one feature 110. In some embodiments, as shown, the conformal liner 122 remains. In other embodiments not shown, the conformal liner 122 is etched such that it is partially or completely removed from at least one feature. In one or more embodiments, the metal layer 124 is selectively removed so that the dielectric material (eg, silicon oxide, silicon nitride layers 104, 106) is not affected.

Throughout the specification, references to "one embodiment," "certain embodiments," "one or more embodiments," or "an embodiment" mean a specific feature, structure, material, or The characteristics are included in at least one embodiment of this disclosure. Therefore, phrases such as "in one or more embodiments", "in certain embodiments", "in one embodiment" or "in an embodiment" appearing in various places throughout the specification are not necessarily Refers to the same embodiment of this disclosure. In addition, in one or more embodiments, specific features, structures, materials, or characteristics may be combined in any suitable manner.

Although the disclosure has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of the disclosure. It will be obvious to those familiar with the art that various modifications and changes can be made to the method and equipment of this disclosure without departing from the spirit and scope of this disclosure. Therefore, it is intended that this disclosure includes modifications and changes within the scope of the accompanying patent application and its equivalent elements.

10: substrate 11: memory string 12: Stack 13: top 14: oxide layer/gap 15: side 16: gap 19: word line 20: Metal 22: Overlay 25: metal oxide 100: substrate 102: substrate 104: Nitride material/silicon nitride layer 106: oxide material/silicon oxide layer 110: Features 112: bottom surface/bottom 114: first side wall/side wall 116: second side wall/side wall 120: substrate surface 122: Conformal lining/metal layer 124: Metal layer 126: Overlay 128: metal oxide layer

Therefore, in order to understand the above-mentioned features of the disclosure in detail, a more detailed description of the disclosure briefly outlined above can be obtained by referring to the embodiments, some of which are shown in the accompanying drawings. The accompanying drawings only show typical embodiments of this disclosure, and therefore should not be considered restrictive, as this disclosure may allow other equivalent embodiments.

Figure 1 shows a stack of oxide layers in which word lines will be formed according to one or more embodiments of the present disclosure;

Figure 2 shows a metal film formed on the stack of oxide layers of Figure 1;

Figures 3A and 3B show high-temperature oxidation and etching treatments according to one or more embodiments of this disclosure;

Figures 4A to 4D show low-temperature oxidation and etching treatments according to one or more embodiments of the present disclosure; and

Figures 5A to 5D show cross-sectional views of substrate features according to one or more embodiments of the present disclosure.

Domestic deposit information (please note in the order of deposit institution, date and number) no Foreign hosting information (please note in the order of hosting country, institution, date, and number) no

100: substrate

102: substrate

104: Nitride material/silicon nitride layer

106: oxide material/silicon oxide layer

122: Conformal lining/metal layer

124: Metal layer

126: Overlay

128: metal oxide layer

Claims (18)

A processing method including the following steps: Depositing a conformal liner in at least one feature on a substrate, wherein the conformal liner includes one or more of titanium nitride (TiN) or tantalum nitride (TaN); Depositing a metal layer on the conformal liner in the at least one feature, the metal layer including a metal; Oxidizing the metal to a first depth to form a metal oxide layer on the metal layer; and The metal oxide layer is etched to selectively remove the metal oxide layer. The method according to claim 1, wherein the metal includes one or more of tungsten (W), titanium (Ti), tantalum (Ta), nickel (Ni), cobalt (Co), or molybdenum (Mo). The method according to claim 2, wherein the metal includes tungsten (W). The method of claim 1, wherein the metal oxide layer includes tungsten oxide (WO). The method of claim 1, wherein the oxidation of the metal occurs at a temperature greater than or equal to 400°C. The method of claim 1, wherein etching the metal oxide layer occurs at a temperature in a range of about 100°C to about 500°C. The method according to claim 1, wherein etching the metal oxide comprises the following steps: exposing the metal oxide to a metal halide etchant. The method according to claim 7, wherein the metal halide etchant comprises one or more of _{WF 6} , WCl ₅ , WCl _{6 or tungsten oxyhalide.} A processing method including the following steps: A metal layer is deposited on a substrate surface, the substrate surface has at least one feature, the at least one feature extends a feature depth from the substrate surface to a bottom surface, and the at least one feature has a first sidewall and a second A width defined by two sidewalls, wherein the metal layer is deposited on the substrate surface, the first sidewall, the second sidewall, and the bottom surface of the at least one feature; and Performing a processing cycle includes the following steps: oxidizing the metal to a first depth to form a metal oxide layer on the metal layer; and etching the metal oxide layer to selectively remove the metal oxide layer. The method according to claim 9, wherein the metal includes tungsten (W), and the metal oxide layer includes tungsten oxide (WO). The method according to claim 9, further comprising the step of depositing a conformal lining in the at least one feature before depositing the metal layer, wherein the conformal lining comprises titanium nitride (TiN) or tantalum nitride (TaN) ) One or more. The method of claim 9, wherein the oxidation of the metal occurs at a temperature greater than or equal to 400°C. The method of claim 9, wherein etching the metal oxide layer occurs at a temperature in a range of about 100°C to about 500°C. The method according to claim 9, wherein etching the metal oxide comprises the following steps: exposing the metal oxide to a metal halide etchant, the metal halide etchant comprising WF ₆ , WCl ₅ , WCl ₆ or halogen One or more types of tungsten oxide. The method according to claim 9, further comprising the following steps: repeat the processing cycle n times. The method according to claim 9, wherein oxidizing the metal layer comprises the following steps: exposing a surface of the metal layer to oxygen (O ₂ ). The method of claim 9, wherein the substrate includes a plurality of alternating oxide layers and nitride layers. A method of processing a substrate, the method comprising the following steps: forming a film stack on a substrate, the film stack including a plurality of alternating layers of oxide materials and nitride materials, and the film stack having a stack thickness; An opening extending a depth from a top to a bottom surface of the film stack surface, the opening having a width defined by a first side wall and a second side wall; optionally on the film stack surface and on the opening A barrier layer is formed on the first sidewall, the second sidewall, and the bottom surface, and the barrier layer includes TiN with a thickness in the range of about 20Å to about 50Å; and a metal layer is deposited on the film stack so that The metal layer fills the opening and covers the top of the film stack with a metal layer thickness; and repeatedly oxidizes the surface of the metal layer to form a metal oxide layer, and etches the metal oxide layer from the at least one feature Until the metal layer is removed, oxidizing the surface includes the following steps: exposing to O ₂ , and etching the metal layer oxide includes the following steps: exposing to a halide etchant.

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