JP7362911B2 - Selective self-limiting tungsten etch process - Google Patents

Description

Embodiments of the present disclosure generally relate to a method of filling gaps or features in a semiconductor device. More particularly, embodiments of the present disclosure relate to a method of gap filling in three-dimensional semiconductor devices using tungsten.

As semiconductor devices become more complex in their design and material composition, selective removal of materials becomes critical to the continued scaling and improvement of semiconductor devices. Atomic Layer Etching (ALE) has emerged as a precision etching method that employs self-limiting surface reactions. Selective ALE of metal oxides (MO _x ) is particularly important for some semiconductor technologies, but can be difficult to accomplish due to the inherent stability of the oxide materials.

V-NAND or 3D-NAND structures are used for flash memory applications. A V-NAND device has a vertically stacked NAND structure in which a large number of cells are arranged in a block shape. Gate last word line formation is currently the mainstream process flow during 3D-NAND manufacturing. Prior to word line formation, the substrate is a layered oxide stack supported by memory strings. The interstitial space is filled with tungsten using CVD or ALD. The top/side walls of the memory stack are also coated with tungsten. An etching process (e.g., a reactive-ion etch (RIE) process or a radical-based etch) so that the tungsten is only inside the interstitial space and each tungsten fill is completely separate from the other tungsten fills. process) removes tungsten from the top/sidewalls of the stack. However, due to the loading effects of the etch process, the word line recesses at the top of the stack are often different from the word line recesses at the bottom for each individual etch. This difference becomes more noticeable as the oxide stack layer increases.

Multilayer VNAND tungsten fill presents many challenges when filling tungsten, especially in buried word lines. Deposition-etch cycle techniques that provide better gap filling are needed. However, at this time, there are no cyclic deposition-etch processes available to provide 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 are directed to a method of processing a substrate. In one or more embodiments, the processing method includes depositing a metal layer on at least one feature on the substrate and 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.

Another embodiment of the present disclosure is directed to a method of processing a substrate. In one or more embodiments, the processing method is to deposit a metal layer on a substrate surface, the substrate surface having at least one feature thereon, the at least one feature extending from the substrate surface to the bottom surface. and a width of the at least one feature is defined by a first sidewall and a second sidewall, and a metal layer extends along the substrate surface and the first sidewall, the second sidewall of the at least one feature. depositing a metal layer and oxidizing the metal to a first depth to form a metal oxide layer on the metal layer, and selectively depositing the metal oxide layer on the sidewalls and the bottom surface; etching the metal oxide layer to remove it; and performing a process cycle that includes: etching the metal oxide layer to remove it.

Further embodiments of the present disclosure are directed to methods of processing a substrate. In one or more embodiments, a method of processing a substrate includes forming a film stack on the substrate, the film stack comprising a plurality of alternating layers of oxide and nitride materials, the film stack comprising a plurality of alternating layers of oxide and nitride materials; forming a film stack having a stack thickness; and forming an aperture extending a depth from a top surface to a bottom surface of the film stack surface, the width of the aperture being equal to the width of the first sidewall and the second sidewall. forming an aperture defined by a barrier layer, and optionally forming a barrier layer on the film stack surface and on a first sidewall, a second sidewall, and a bottom surface of the aperture, the barrier layer being defined by a barrier layer; forming a barrier layer, the layer comprising TiN having a thickness in the range of about 20 Å to about 50 Å; and depositing a metal on the film stack such that the metal layer fills the opening and covers the top surface of the film stack with a metal layer thickness. depositing a layer and repeatedly oxidizing a surface of the metal layer to form a metal oxide layer and etching the metal oxide layer from the at least one feature until the metal layer is removed; Oxidizing the surface includes exposing the metal layer oxide to _O2 , and etching the metal layer oxide includes exposing the metal oxide layer to a halide etchant.

In order that the features of the disclosure described above may be understood in more detail, the disclosure briefly summarized above will now be described more specifically with reference to embodiments, some of which are illustrated in the accompanying drawings. be able to. The accompanying drawings depict only typical embodiments of the disclosure and should not be taken as limiting, as the disclosure may accommodate other equally valid embodiments.

FIG. 3 illustrates an oxide layer stack in which word lines are formed, according to one or more embodiments of the present disclosure. 2 shows a metal film formed on the oxide layer stack of FIG. 1; FIG. FIG. 3 illustrates a high temperature oxidation and etching process in accordance with one or more embodiments of the present disclosure. FIG. 3 illustrates a high temperature oxidation and etching process in accordance with one or more embodiments of the present disclosure. FIG. 3 illustrates a low temperature oxidation and etch process in accordance with one or more embodiments of the present disclosure. FIG. 3 illustrates a low temperature oxidation and etch process in accordance with one or more embodiments of the present disclosure. FIG. 3 illustrates a low temperature oxidation and etch process in accordance with one or more embodiments of the present disclosure. FIG. 3 illustrates a low temperature oxidation and etch process in accordance with one or more embodiments of the present disclosure. 2 is a cross-sectional view of a substrate feature in accordance with one or more embodiments of the present disclosure. FIG. 2 is a cross-sectional view of a substrate feature in accordance with one or more embodiments of the present disclosure. FIG. 2 is a cross-sectional view of a substrate feature in accordance with one or more embodiments of the present disclosure. FIG. 2 is a cross-sectional view of a substrate feature in accordance with one or more embodiments of the present disclosure. FIG.

Before describing some exemplary embodiments of the present disclosure, it is understood that this disclosure is not limited to the details of construction or process steps set forth in the detailed description below. Should. The present disclosure is susceptible to other embodiments and can be practiced or performed in various ways.

As used herein and in the appended claims, the terms "substrate" and "wafer" are used interchangeably and both refer to a surface or portion of a surface on which a process operates. be. Those skilled in the art will appreciate that references to a substrate may refer to only a portion of the substrate, unless the context clearly dictates otherwise. Also, references to depositing on a substrate may refer to both bare substrates and substrates on which one or more films or features have been deposited or formed.

As used herein, "substrate" refers to any substrate on which a film treatment is performed during the manufacturing process, and any material surface formed on the substrate. For example, the substrate surface on which the treatment may be performed may be silicon, silicon oxide, strained silicon, silicon on insulator (SOI), carbon-doped silicon oxide, amorphous silicon, doped silicon, Including materials such as germanium, gallium arsenide, glass, sapphire, and any other materials such as metals, metal nitrides, metal alloys, and other conductive materials. Substrates include, but are not limited to, semiconductor wafers. The substrate can be subjected to pretreatment processes such as polishing, etching, reducing, oxidizing, hydroxylating, tempering, UV curing, e-beam curing, and/or baking the substrate surface. In addition to directly coating the surface of the substrate itself, this disclosure also provides that any of the disclosed coating steps may also be performed on underlying layers formed on the substrate, as disclosed in more detail below. Often, the term "substrate surface" is intended to include such underlying layers, as the context indicates. Thus, for example, if a film/layer or partial film/layer is deposited on the substrate surface, the exposed surface of the newly deposited film/layer becomes the substrate surface.

Semiconductor manufacturing processes often involve depositing materials, such as tungsten (W), into features such as, but not limited to, vias or trenches to form contacts or interconnects. Chemical Vapor Deposition (CVD) is often used to deposit metals, such as tungsten (W), into features, where the substrate with at least one feature to be filled is filled with metal. A metal-containing precursor and a reducing agent are exposed to deposit into the feature. However, as devices shrink, features become smaller and CVD filling becomes more challenging, especially in advanced logic and memory applications.

In one or more embodiments of the present disclosure, it is advantageous to provide a method for depositing a tungsten film in a gap in a three-dimensional substrate. Some embodiments of the present disclosure advantageously provide methods of depositing conformal tungsten oxide films and methods of selective tungsten oxide removal. In some embodiments, it is advantageous to provide a method for filling the lateral features of a V-NAND with a high quality tungsten film of uniform thickness from the top to the bottom of the oxide stack. In one or more embodiments, the processing method advantageously does not use plasma. Additionally, the processing method of one or more embodiments advantageously selectively removes tungsten at a rate that is more consistent than other deep etching techniques.

One or more embodiments of the present disclosure are directed to methods of word line isolation based on highly conformal metal (e.g., tungsten) oxide and highly selective metal oxide (e.g., tungsten oxide) removal. It is. This method can be used in both high temperature and low temperature processes.

One or more embodiments of the present disclosure are directed to a deposition-etch ("deep etch") cycle technique that provides better gap filling. The method of one or more embodiments facilitates such deep etch cycle processes. Also, in one or more embodiments, contact resistance of the semiconductor device is increased because native oxide is removed from the surface of the metal, such as tungsten.

Referring to FIG. 1, there is a layer stack 12 on a substrate 10. Substrate 10 may be any suitable substrate material and is not limited to being the same material as any of the individual layers. For example, in some embodiments the substrate is an oxide layer, a nitride layer, or a metal layer. The stack 12 has a plurality of oxide layers 14 spaced apart from one another to form gaps 16 between the oxide layers 14 such that each gap forms a word line or a contour in which a word line is formed. There is. Stack 12 has a top surface 13 and side surfaces 15.

Stack 12 may include any suitable number of oxide layers 14 or gaps 16. In some embodiments, about 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100 or more gaps 16 are formed in the stack 12, which may be used to form an equal number of word lines. ing. The number of gaps 16 is measured on either side of the memory string 11 connecting all of 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 approximately 96.

As shown in FIG. 2, metal 20 is deposited on stack 12. Metal 20 fills the gap 16 and forms the word line 19. The outer shape of the metal 20 is formed around the entire circumference of the stack 12 such that the metal 20 covers the top surface 13 and side surfaces 15 of the stack 12 with the thickness of the metal overburden 22 . Overburden 22 is material deposited outside of gap 16. The overburden can be any thickness that is compatible with the process used to deposit metal 20. In some embodiments, the thickness of overburden 22 ranges from about 1 Å to about 1000 Å. In some embodiments, overburden 22 has a thickness of about 5 Å, 10 Å, 15 Å, 20 Å, 25 Å, 30 Å, 35 Å, 40 Å, 45 Å, or 50 Å or more.

Metal 20 may be any metal suitable for use in word line applications. In some specific embodiments, the metal film includes tungsten. In some specific embodiments, the metal film excludes tungsten. In some specific embodiments, the metal film consists essentially of tungsten. As used in this context, the phrase "consisting essentially of tungsten" means that the bulk metal film is comprised of greater than or equal to about 95%, 98%, or 99% tungsten on an atomic basis. The bulk metal film excludes surface portions of the metal 20 that may be in contact with another surface (e.g., an oxide surface) or available for further processing; There may be some small scale atomic diffusion through the matching material, or there may be some surface moieties such as hydride terminations.

Metal 20 can be deposited by any suitable technique, including but not limited to chemical vapor deposition (CVD) or atomic layer deposition (ALD). Metal 20 is deposited in the interstitial spaces and on the top/sides of the memory stack.

Referring to FIGS. 3A and 3B, a high temperature oxidation with a low temperature etch process is shown. In FIG. 3A, metal 20 is oxidized to form metal oxide 25 with a depth approximately equal to the thickness of overburden 22. In FIG. Substantially all of the overburden 22 can be oxidized in a one-step oxidation process. Oxidation of the overburden can be influenced by, for example, oxidizing gas flow, oxidizing gas partial pressure, wafer temperature, and process time to form highly conformal oxidized metal overburden 22.

The oxidizing gas may be any suitable oxidizing gas capable of reacting with the deposited metal 20. Suitable oxidizing gases include, but _are not limited to, _O2 , _O3 , _H2O , _H2O2 , NO, _NO2 , or combinations thereof. In some embodiments, the oxidizing gas includes one or more of _O2 or _O3 . In some embodiments, the oxidizing gas consists essentially of one or more of _O2 or _O3 . As used in this manner, the phrase "consisting essentially of" means that the oxidizing component of the oxidizing gas is about 95%, 98%, or 99% or more of the stated species. The oxidizing gas can include an inert gas, a diluent gas, or a carrier gas. For example, the oxidizing gas may be in parallel flow with one or more of Ar, He, or N ₂ or diluted with one or more of Ar, He, or N ₂ .

Metal oxide 25 in some embodiments includes tungsten oxide (WO _x ). In some embodiments, metal oxide 25 is a derivative of metal 20, which may or may not contain oxygen. Suitable derivatives of metal films are nitrides, borides, carbides, oxynitrides, oxyborides, oxycarbides, carbonitrides, boron carbide, boron nitride, boron carbonitride, boron oxycarbonitride, oxycarbonitride , boron oxycarbide, and boron oxynitride. Those skilled in the art will appreciate that the deposited metal film may have non-stoichiometric amounts of atoms with respect to the metal film. For example, in a film designated as WO, the amount of tungsten and the amount of oxygen may be different. The WO film may be, for example, 90 atomic percent tungsten. Using WO to describe a tungsten oxide film means that although the film is composed of tungsten and oxygen atoms, the film should not be viewed as limited to any particular composition. means. In some embodiments, the film consists essentially of the atoms shown. For example, a film consisting essentially of WO means that the composition of the film is greater than about 95%, 98%, or 99% tungsten and oxygen atoms.

In the process shown in FIGS. 3A and 3B, the oxidation process is performed at high temperatures. As used in this context, the term "high temperature" means a temperature of about 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, or 850°C or above. do. In some embodiments, the temperature of the oxidation process ranges from about 400°C to about 950°C, from about 450°C to about 900°C, or from about 500°C to about 850°C.

Pressures during the oxidation process may range from about 0.1 Torr to about 760 Torr. Process times (exposure times) may range from about 0.1 seconds to 12 hours. Pressure and process time can be affected by temperature during the oxidation process.

In some embodiments, the metal 20 of the overburden 22 is oxidized to form metal oxide 25 on the top surface 13 and side surfaces 15 of the stack 12 while leaving metal 20 in the gaps 16 that form the word lines 19. In some embodiments, substantially all of the metal 20 remains in the gap 16 after oxidation. As used in this manner, the phrase "substantially all" means that the metal 20 is oxidized to a range of ±1 Å on the sides 15 of the stack 12.

Referring to FIG. 3B, metal oxide 25 formed from overburden 22 is etched from top surface 13 and side surface 15 of stack 12, leaving metal 20 in gap 14 as word line 19. The etching process of some embodiments is a selective etching process that removes metal oxide 25 without substantially affecting 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 context, the phrase "consisting essentially of a metal halide etchant" means that the identified metal halide etchant species account for 95%, 98%, or 99% of the total metal halide etchant species. (contains no inert, diluent, or carrier gases). The metal species of the metal halide etchant may be the same as or different from the metal species of the metal oxide 25. In some embodiments, the metal species of the metal halide etchant is the same as the metal species of the metal oxide 25.

In some embodiments, the metal halide etchant includes halogen atoms consisting essentially of chlorine. When used in this context, the phrase "consisting essentially of chlorine" means that chlorine makes up about 95%, 98%, or 99% or more of the halogen atoms in the metal halide etchant on an atomic basis. means. In some embodiments, the metal halide etchant includes halogen atoms consisting essentially of fluorine. When used in this context, the phrase "consisting essentially of fluorine" means that fluorine makes up about 95%, 98%, or 99% or more of the halogen atoms in the metal halide etchant on an atomic basis. means.

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 _WF5 , _WCl5 , or _WCl6 . When used in this context, the phrase "consisting essentially of" means that the described species constitutes about 95%, 98%, or 99% or more of the metal halide on a molecular basis. do.

The etching temperature of some embodiments is lower than the temperature during oxidation. In some embodiments, the etching temperature ranges from about 300°C to about 600°C, or from about 400°C to about 500°C. In some embodiments, the etching temperature is about 600°C, 550°C, 500°C, 450°C, 400°C, or 350°C or less. In some embodiments, the temperature during etching is about 50°C, 75°C, 100°C, 125°C, or 150°C or higher and lower than the temperature during oxidation. In some embodiments, both the oxidation and etching are performed at a temperature of about 300° C. or higher.

After etching the metal oxide 25, the metal overburden 22 is removed, leaving the metal 20 in the gap 14 as the word line 19 substantially coplanar with the sides 15 of the stack 12. As used in this manner, the phrase "substantially coplanar" means that the word lines 19 within the gap 16 are within ±1 Å of the sides 15 of the stack 12.

In the embodiment shown in FIGS. 3A and 3B, a high temperature oxidation-low temperature etch process is visible. In the embodiment shown in FIGS. 4A-4D, a low temperature oxidation and etching process is visible. Some differences between the processes include, but are not limited to, lower temperature oxidation and slower overburden removal.

After the stack 12 has an overburden 22 of metal 20 (as seen in FIG. 2), removal of the overburden may be performed by an atomic layer etching type process. Atomic layer etching processes may involve multiple repetitions of the process of modifying the surface to be etched and then volatilizing or removing the modified surface to expose the new surface below.

Referring to FIG. 4A, overburden 22 is oxidized to form metal oxide 25 on the surface of overburden 22. Referring to FIG. The oxidation process can use the same reagents and parameters as the embodiment shown in FIG. 3A, with some modifications to allow for an atomic layer etch (ALE) process. The oxidation process of some embodiments is conducted at a temperature ranging from about 300°C to about 500°C. In some embodiments, oxidation occurs at a temperature of about 500°C, 450°C, 400°C, or 350°C or less. Pressures during the low temperature oxidation process may range from about 0.1 Torr to about 760 Torr. Process or exposure times may range from about 0.001 seconds to about 60 seconds. In atomic layer etching processes, each oxidation and etching process is self-limiting in that the process stops when available surface sites react. For example, once all of the available surface sites of metal 20 are exposed to and react with the oxidizing agent, resulting in a metal oxide 25 film, further oxidation cannot occur immediately. Similarly, once the etchant removes the oxide film and exposes new metal 20 underneath, there is no more oxide for the etchant to remove.

Referring to FIG. 4B, after the formation of metal oxide 25 on metal 20, stack 12 is exposed to an etchant. The etchant and etching conditions may be the same as shown in and described in connection with FIG. 3B. Because the metal oxide 25 layer on metal 20 is thinner than the embodiment shown in FIGS. 3A and 3B, the etching process is shorter. In some embodiments, the etchant process time ranges from about 0.1 seconds to about 60 seconds.

In some embodiments, the temperature during the oxidation process and the etching process are performed at a temperature of about 400°C or less. As shown in FIG. 4B, the substrate containing the stack 12 can be quickly moved from one process area of the processing chamber to another process area of the processing chamber, sequentially subjecting the substrates to oxidizing and etching conditions. The temperature of the etching process can be the same as the oxidation process of FIG.

This type of ALE process is sometimes referred to as spatial ALE, in which various reactant gases (eg, oxidants and etchants) flow into separate regions of the processing chamber and the substrate is moved between and within regions. The various process areas are separated by gas curtains consisting of one or more of a purge gas stream and/or a vacuum stream to prevent mixing of oxidant and etchant in the gas phase. The ALE process is a process in which a processing chamber is filled with an oxidant, purged to remove excess oxidant and reaction products or byproducts, and filled with etchant to remove excess etchant and reaction products or byproducts. It can also be done by a time domain process where the product is purged to remove it. In time domain processes, the substrate can remain stationary.

FIG. 4C shows the formation of metal oxide 25 by repeated exposure to an oxidizing agent, and FIG. 4D shows the removal of the metal oxide by repeated exposure to an etchant. Although the process is shown as using two cycles, those skilled in the art will appreciate that this is just an illustration and that two cycles are used to remove overburden 22 and leave metal 20 in gap 16 as word line 19. It will be appreciated that more cycles may be used.

In some embodiments, a barrier layer is formed on oxide layer 14 prior to metal 20 deposition. 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. As used in this manner, the phrase "consisting essentially of titanium nitride" means that the barrier layer consists of approximately 95%, 98%, or 99% or more titanium atoms and nitrogen atoms, atomically; It means that. The thickness of each wall covering may be any suitable thickness. In some embodiments, the thickness of the barrier layer ranges from about 20 Å to about 50 Å.

5A-5D illustrate a partial cross-sectional view of a substrate 100 with features 110 and details an atomic layer etch process, according to one or more embodiments of the present disclosure. Although these figures show substrates with only one feature for purposes of aiding understanding, those skilled in the art will recognize that there may be more than one feature. Features 110 can be any suitable shape, including, but not limited to, trenches and cylindrical vias. As used in this context, the term "feature" refers to any intentional surface irregularity. Suitable examples of features include, but are not limited to, a trench with a top surface, two sidewalls, and a bottom surface, a peak with a top surface and two sidewalls. The feature aspect ratio (ratio of feature depth to feature width) may be any suitable ratio. In some embodiments, the aspect ratio is about 5:1, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, or 40:1 or greater.

Substrate 100 has a substrate surface 120 . At least one feature 110 defines an opening in the substrate surface 120. At least one feature 110 extends a feature depth D _f from the substrate surface 120 to the bottom surface 112 . At least one feature 110 has a first sidewall 114 and a second sidewall 116 defining a width W of the at least one feature 110. The open area formed by side walls 114, 116 and bottom 112 is also referred to as a gap. In one or more embodiments, width W is uniform across depth D1 of at least one feature 110. In other embodiments, the width W of the top surface of at least one feature 110 is greater than the width W of the bottom surface 112 of at least one feature 110.

In one or more embodiments, substrate 100 is a film stack comprised of multiple alternating layers of nitrogen material 104 and oxide material 106 deposited on a semiconductor substrate 102.

The material of semiconductor substrate 102 may be any suitable substrate material. In one or more embodiments, semiconductor substrate 102 is made of a semiconductor material, such as silicon (Si), carbon (C), germanium (Ge), silicon germanium (SiGe), gallium arsenide (GaAs), indium phosphate ( InP), indium gallium arsenide (InGaAs), indium aluminum arsenide (lnAlAs), germanium (Ge), silicon germanium (SiGe), copper indium gallium selenide (CIGS), other semiconductor materials, or any combination thereof. In one or more embodiments, semiconductor substrate 102 is silicon (Si), germanium (Ge), gallium (Ga), arsenic (As), indium (In), phosphorus (P), copper (Cu), or Contains one or more of selenium (Se). Although a few examples of materials from which substrate 102 may be formed are mentioned herein, passive and active electronic devices (e.g., transistors, memories, capacitors, inductors, resistors, switches, integrated circuits, Any material that can serve as a basis from which an amplifier, optoelectronic device, or any other electronic device can be assembled falls 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. Accordingly, in one or more embodiments, substrate 100 includes a memory or logic device, such as a NAND, V-NAND, DRAM, or the like.

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

As used herein, the term "dynamic random access memory" or "DRAM" refers to a memory that stores a reference bit (i.e., a binary 1) by storing a packet of charge on a capacitor, or stores a charge packet on a capacitor. Refers to a memory cell that does not store any data (ie, binary 0). Charge is gated into a capacitor through an access transistor and sensed by turning on that same transistor and looking at the voltage perturbation caused by dumping a charge packet onto an interconnect line at the transistor output. Thus, a single DRAM cell is made of one transistor and one capacitor.

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

Referring to FIG. 5C, after overburden 126 and, optionally, metal layer 124 with conformal liner 122 are deposited, removal of overburden 126 may be performed by an atomic layer etching type process. Atomic layer etching processes may involve multiple repetitions of modifying the surface being etched and then volatilizing or removing the modified surface to expose the new surface below.

Referring to FIG. 5C, overburden 126 is oxidized to form a metal oxide layer 128 on the surface of overburden 126. In one or more embodiments, metal layer 122 is oxidized to a metal oxide layer 128 as deep as the thickness of overburden 126. Substantially all of the overburden 126 can be oxidized in a one-step oxidation process. Oxidation of overburden 126 in forming highly conformal oxidized metal overburden 126 can be influenced by, for example, oxidizing gas flow, oxidizing gas partial pressure, wafer temperature, and process time.

In one or more embodiments, the oxidizing gas is any suitable oxidizing gas capable of reacting with the deposited metal layer 122. Suitable oxidizing gases include, but _are not limited to, _O2 , _O3 , _H2O , _H2O2 , NO, _NO2 , or combinations thereof. In some embodiments, the oxidizing gas includes one or more of _O2 or _O3 . In some embodiments, the oxidizing gas consists essentially of one or more of _O2 or _O3 . As used in this manner, the phrase "consisting essentially of" means that the oxidizing component of the oxidizing gas is about 95%, 98%, or 99% or more of the stated species. The oxidizing gas can include an inert gas, a diluent gas, or a carrier gas. For example, the oxidizing gas may be in parallel flow with one or more of Ar, He, or _N2 , or diluted with one or more of Ar, He, or _N2 . good.

Metal oxide layer 128 in some embodiments includes tungsten oxide (WO _x ). In some embodiments, metal oxide layer 128 is a derivative of metal layer 122, which may or may not include oxygen. Suitable derivatives of metal layer 122 include nitride, boride, carbide, oxynitride, oxyboride, oxycarbide, carbonitride, boron carbide, boron nitride, boron carbonitride, boron oxycarbonitride, oxycarbonitride. boron oxycarbide, and boron oxynitride. Those skilled in the art will appreciate that the deposited metal layer 122 may have non-stoichiometric amounts of atoms with respect to the metal film. For example, metal layer 122, designated as WO, may have different amounts of tungsten and oxygen. The WO film may be, for example, 90 atomic percent tungsten. The use of WO to describe a tungsten oxide film means that although the film contains tungsten and oxygen atoms, the film should not be viewed as limited to any particular composition. In some embodiments, the film consists essentially of the atoms shown. For example, a film consisting essentially of WO means that the composition of the film is greater than about 95%, 98%, or 99% tungsten and oxygen atoms.

In the process shown in FIGS. 5A-5D, the oxidation process is performed at high temperatures, where the oxidation is a thermal oxidation, fast thermal oxidation, or spike annealing process. As used in this context, the term "high temperature" means a temperature of about 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, or 850°C or higher. , means. In some embodiments, the temperature of the oxidation process ranges from about 400°C to about 950°C, from about 450°C to about 900°C, or from about 500°C to about 850°C.

In one or more embodiments, the pressure during the oxidation process ranges from about 0.1 Torr to about 760 Torr. Process times (exposure times) may range from about 0.1 seconds to 12 hours. Pressure and process time can be affected by temperature during the oxidation process.

In some embodiments, the metal layer 124 of the overburden 126 is oxidized to form a metal oxide layer 128 on the top surface 130 and side surface 132 of the at least one feature 110 while the metal layer 124 is oxidized on the at least one feature 110. leave. In some embodiments, substantially all of the metal layer 124 remains on at least one feature 110 after oxidation. As used in this manner, the phrase "substantially all" means that the metal layer 124 is oxidized to within ±1 Å of the side surface 132 of at least one feature 110.

Referring to FIG. 5D, the metal oxide layer 128 formed from the overburden 126 is etched from the top surface 130 and side surfaces 132, leaving the metal layer 124. The etching process of some embodiments is a selective etching process that removes metal oxide layer 128 without substantially affecting 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 context, the phrase "consisting essentially of a metal halide etchant" means that the identified metal halide etchant species account for 95%, 98%, or 99% of the total metal halide etchant species. (contains no inert, diluent, or carrier gases). The metal chemistry of the metal halide etchant may be the same as or different from the metal chemistry of metal oxide layer 128. In some embodiments, the metal species of the metal halide etchant is the same as the metal species of metal oxide layer 128.

In some embodiments, the metal halide etchant includes halogen atoms consisting essentially of chlorine. In other embodiments, the metal halide etchant includes halogen atoms consisting essentially of fluorine. When used in this context, the phrase "consisting essentially of fluorine" means that fluorine constitutes about 95%, 98%, or 99% or more of the halogen atoms in the metal halide etchant, atomically. It means that.

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 context, the phrase "consisting essentially of" means that the stated species constitutes about 95%, 98%, or 99% or more of the metal halide on a molecular basis. means.

The etching temperature of some embodiments is lower than the temperature during oxidation. In some embodiments, the etching temperature ranges from about 100°C to about 600°C, or from about 100°C to about 500°C. In some embodiments, the etching temperature is about 600°C, 550°C, 500°C, 450°C, 400°C, or 350°C or less. In some embodiments, the temperature during etching is about 50°C, 75°C, 100°C, 125°C, or 150°C or higher and lower than the temperature during oxidation. In some embodiments, etching is performed at about 300°C. In some embodiments, both oxidation and etching occur above about 400°C.

The oxidation process of some embodiments is conducted at a temperature ranging from about 300°C to about 500°C. In some embodiments, oxidation occurs at a temperature of about 500°C, 450°C, 400°C, or 350°C or less. Pressures during the low temperature oxidation process may range from about 0.1 Torr to about 760 Torr. Process or exposure times may range from about 0.001 seconds to about 60 seconds. In atomic layer etching processes, each oxidation and etching process is self-limiting in that the process stops when available surface sites react. For example, once all of the available surface sites of metal layer 124 are exposed to and react with the oxidant to form metal oxide layer 128, further oxidation cannot readily occur. Similarly, when the etchant removes the metal oxide layer 128 and exposes the new metal layer 124 underneath, there is no oxide to be removed by the etchant.

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

In one or more embodiments, this type of ALE process involves a spatial process in which various reactant gases (e.g., oxidants and etchants) flow into separate regions of the processing chamber, and the substrate moves between and within regions. It is sometimes called ALE. The various process areas are separated by gas curtains comprised of one or more of a purge gas stream and/or a vacuum stream to prevent mixing of oxidant and etchant in the gas phase. The ALE process consists of filling a processing chamber with an oxidant, purging it to remove excess oxidant and reaction products or byproducts, and filling the chamber with etchant to remove excess etchant and reaction products or byproducts. It can also be done by a time domain process where the product is purged to remove it. In time domain processes, the substrate can remain stationary.

After etching metal oxide 128, the process is repeated to oxidize metal layer 124 to metal oxide layer 128 and then etch metal oxide layer 128 to remove the oxide layer. Although this process is shown as using only one cycle, those skilled in the art will appreciate that this is merely an indication and that more than two cycles may be used to remove metal layer 124. You will find that it is good. In one or more embodiments, the process repeats the process cycle n times. In one or more embodiments, n is a number ranging from about 2 to about 2000. 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.

The process is completed in a layer-by-layer manner until metal layer 124 is selectively removed from at least one feature 110, as shown in FIG. 5D. In some embodiments, a conformal liner 122 remains, as shown. 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, metal layer 124 is selectively removed so as not to affect the dielectric material (eg, silicon oxide layer 104, silicon nitride layer 106).

Throughout this specification, references to "one embodiment," "a particular embodiment," "one or more embodiments," or "an embodiment" refer to specific features discussed in the context of that embodiment. , a structure, material, or property is included in at least one embodiment of the present disclosure. Therefore, the phrases "in one or more embodiments," "in a particular embodiment," "in one embodiment," or "in an embodiment" appear in various places throughout this specification. references herein are not necessarily referring to the same embodiments of the disclosure. Additionally, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.

Although the disclosure herein has been described in the context of particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the disclosure. It will be apparent to those skilled in the art that various modifications and changes can be made to the methods and apparatus of the present disclosure without departing from the spirit and scope of the disclosure. Accordingly, it is intended that this disclosure cover the modifications and variations that come within the scope of the appended claims and their equivalents.

Claims (18)

depositing a conformal liner on at least one feature on a substrate, the conformal liner comprising one or more of titanium nitride (TiN) or tantalum nitride (TaN); depositing a conformal liner, the liner being deposited on the surface of the substrate and on the sidewalls and bottom of an aperture in the substrate, the aperture extending a depth from the surface to the bottom of the substrate;
depositing a metal layer on the conformal liner in the at least one feature, the metal layer comprising a metal;
oxidizing the metal to a first depth to form a metal oxide layer on a portion of the metal layer deposited above the surface of the substrate ;
etching the metal oxide layer to selectively remove the metal oxide layer. 2. The metal of claim 1, wherein the metal includes one or more of tungsten (W), titanium (Ti), tantalum (Ta), nickel (Ni), cobalt (Co), or molybdenum (Mo). Method. 3. The method of claim 2, wherein the metal comprises tungsten (W). 2. The method of claim 1, wherein the metal oxide layer comprises tungsten oxide (WO). 2. The method of claim 1, wherein oxidizing the metal is performed at a temperature of 400<0>C or higher. The method of claim 1 , wherein etching the metal oxide layer is performed at a temperature in the range of 100 °C to 500 °C. 2. The method of claim 1, wherein etching the metal oxide layer includes exposing the metal oxide layer to a metal halide etchant. 8. The method of claim 7, wherein the metal halide etchant comprises one or more of _WF6 , _WCl5 , _WCl6 , or tungsten oxyhalide. depositing a metal layer on a substrate surface, the substrate surface having at least one feature thereon, the at least one feature extending a feature depth from the substrate surface to a bottom surface; a width of a feature is defined by a first sidewall and a second sidewall , and a metal layer including a metal is formed on the substrate surface and the first sidewall, the second sidewall of the at least one feature. , and depositing a metal layer deposited on the bottom surface;
oxidizing the metal to a first depth to form a metal oxide layer on a portion of the metal layer deposited above the substrate surface ; and selectively removing the metal oxide layer. etching the metal oxide layer; and performing a process cycle comprising: etching the metal oxide layer. 10. The method of claim 9, wherein the metal comprises tungsten (W) and the metal oxide layer comprises tungsten oxide (WO). The method further comprises depositing a conformal liner on the at least one feature prior to depositing the metal layer, the conformal liner being one of titanium nitride (TiN) or tantalum nitride (TaN) or 10. The method of claim 9, comprising a plurality. 10. The method of claim 9, wherein oxidizing the metal is performed at a temperature of 400<0>C or higher. A method according to claim 9, wherein etching the metal oxide layer is performed at a temperature in the range of 100 °C to 500 °C. Etching the metal oxide layer includes exposing the metal oxide layer to a metal halide etchant comprising one or more of _WF6 , _WCl5 , _WCl6 , or tungsten oxyhalide. 10. The method according to claim 9. 10. The method of claim 9, further comprising repeating the process cycle n times. 10. The method of claim 9, wherein oxidizing the metal layer includes exposing a surface of the metal layer to oxygen ( _O2 ). 10. The method of claim 9, wherein the substrate comprises a plurality of alternating layers of oxide and nitride. A method of processing a substrate, the method comprising:
forming a film stack on at least one feature on a substrate, the film stack comprising a plurality of alternating layers of oxide and nitride materials, the film stack having a stack thickness; to form a
forming an aperture extending a depth from a top surface to a bottom surface of the film stack , the width of the aperture being defined by a first sidewall and a second sidewall ;
Optionally , forming a barrier layer on a top surface of the film stack and on the first sidewall, the second sidewall, and the bottom surface of the aperture, the barrier layer comprising two forming a barrier layer comprising TiN having a thickness in the range of 0 Å to 50 Å;
depositing a metal layer on the film stack such that the metal layer closes the opening and covers the top surface of the film stack with a metal layer thickness;
Repeatedly oxidizing the surface of the metal layer to form a metal oxide layer on the portions of the metal layer deposited above the top surface of the film stack , until the metal layer is removed. etching the metal oxide layer from one feature, oxidizing the surface comprising exposing to O ₂ and etching the metal oxide layer comprising exposing to a halide etchant; etching the metal oxide layer.

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