Chemical etching of molybdenum films

Abstract

The present disclosure relates to a method for etching a molybdenum (Mo) film and a system for performing the method. The disclosed method includes exposing a substrate comprising an outer layer of Mo to an oxygen-containing reactant to convert at least a portion of the outer layer of Mo to molybdenum oxide (MoOx), then exposing the substrate to an etchant comprising one or more S-X bonds, P-X bonds, and Si-X bonds, where X is Cl or Br, to convert the molybdenum oxide to a volatile Mo-containing compound removed from a surface of the substrate, and then exposing the substrate to an etchant comprising one or more S-X bonds, P-X bonds, and Si-X bonds. Therefore, the thickness of the Mo outer layer is reduced.

Description

Technical Field

[0001] The present disclosure relates to methods and systems for etching molybdenum films and using the methods and systems in semiconductor device fabrication. Background Art

[0002] Molybdenum is a candidate metal for a variety of applications in next-generation semiconductor devices. For example, molybdenum is a potential core metal replacement for local interconnects in logic devices. Compared to copper (the incumbent metal), molybdenum has a lower resistivity (ρ), so using molybdenum can enable narrower, more tightly spaced interconnects that do not require barrier layers. Molybdenum is also a potential replacement metal in future 3D NAND and 3D DRAM memory devices. For example, compared to tungsten, the incumbent metal in 3D NAND devices, molybdenum has a lower resistivity (ρ) and a higher work function, which can enable thinner, longer word lines with larger effective barriers to delay the start of electron injection from the gate during erase operations. In order to enable high-volume manufacturing of such next-generation devices, improved deposition and etching methods for molybdenum are needed.

[0003] Atomic layer etching (ALE) is a method that allows for uniform and precise removal of nanoscale materials from film surfaces. ALE is typically achieved by functionalizing the surface to increase its chemical reactivity, followed by a removal step of the functionalized layer. Molybdenum ALE methods are known and typically rely on the use of plasma for one or both of the functionalization and removal steps. However, plasma-based methods can be problematic for forming ultra-high aspect ratio features, such as those required for future 3D NAND and 3D DRAM structures, due to the recombination of radicals formed in the plasma; therefore, thermal ALE methods are preferred. Thermal ALE methods for molybdenum have been reported; however, they are unnecessarily complex, requiring multiple etching steps per ALE cycle. Methods for etching molybdenum require further innovation to enable their use in high aspect ratio structures and high-volume manufacturing. The present disclosure addresses and satisfies these needs.

[0004] Any discussion set forth in this section, including discussion of problems and solutions, has been included in the present disclosure merely to provide a context for the present disclosure. Such discussion should not be considered as an admission that any information was known or constituted prior art at the time of the invention. Summary of the invention

[0005] This summary is provided to introduce some concepts in a simplified form. These concepts are further described in detail in the detailed description of the example embodiments disclosed below. This summary is not intended to identify the key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0006] One aspect of the present disclosure relates to a method for etching a molybdenum-containing film. The method includes providing a substrate including a molybdenum-containing film in a reaction space, and exposing the substrate to a first etchant to convert at least a portion of the molybdenum-containing film into a volatile Mo-containing compound, thereby reducing the thickness of the molybdenum-containing film. In some embodiments, the molybdenum-containing film includes an outer region or layer located above the bulk region, wherein the outer region or layer includes molybdenum oxide (MoO x ), the bulk region comprises metallic molybdenum. At least a portion of the outer region or layer is converted into a volatile Mo-containing compound.

[0007] In addition, other aspects of the present disclosure relate to a method for etching molybdenum (Mo) from a substrate surface. The method includes providing a substrate including a Mo outer layer having an initial thickness in a reaction space and performing a cyclic etching process. The cyclic etching process includes: exposing the substrate to an oxygen-containing reactant to convert at least a portion of the Mo outer layer into molybdenum oxide (MoO x ); purging the reaction space; exposing the substrate to a first etchant to remove MoO x The etchant comprises one or more of a SX bond, a PX bond, and a Si-X bond, wherein X is Cl or Br; and a purging reaction space. The cyclic etching process can be repeated to reduce the initial thickness of the Mo outer layer to a final thickness, or to remove the Mo outer layer from the substrate.

[0008] In some embodiments, the cyclic etching process further includes exposing the substrate to a second etchant to remove the non-Mo oxide layer from the surface of the substrate, and purging the reaction space after exposing the substrate to the second etchant.

[0009] In some embodiments, the method further comprises performing a continuous etching step before the cyclic etching process, wherein the continuous etching step comprises exposing the substrate to a continuous etchant. In some embodiments, the continuous etching step comprises exposing the substrate to the continuous etchant, and purging the reaction space after exposing the substrate to the continuous etchant.

[0010] In some embodiments, the method further includes maintaining the temperature of the substrate at a set temperature.

[0011] Another aspect of the present disclosure relates to a system for etching molybdenum (Mo) from a substrate surface, such as a semiconductor device. The system includes: a reaction space for accommodating a substrate, the substrate including a Mo outer layer having an initial thickness; a first source for providing an oxygen-containing reactant connected to the reaction space gas via a first valve; a second source for providing a first etchant connected to the reaction space gas via a second valve, wherein the first etchant includes one or more of a SX bond, a PX bond, and a Si-X bond, wherein X is Cl or Br; and a controller operably connected to the first valve and the second valve. The controller is configured and programmed to perform a cyclic etching process, which sequentially includes: opening a first valve to the first source to supply an oxygen-containing reactant into the reaction space, wherein the oxygen-containing reactant converts at least a portion of the Mo outer layer into molybdenum oxide (MoO x ); closing a first valve leading to a first source to stop supplying an oxygen-containing reactant to the reaction space; opening a second valve leading to a second source to supply a first etchant to the reaction space, wherein the first etchant converts MoO x The controller can be further programmed to sequentially repeat opening the first valve to the first source, closing the first valve to the first source, opening the second valve to the second source, and closing the second valve to the second source to reduce the initial thickness of the Mo outer layer to the final thickness or remove the Mo outer layer from the substrate.

[0012] In some embodiments, the system further comprises a third source for providing a second etchant in gas communication with the reaction space via a third valve, and the controller is also operably connected to the third valve and is configured and programmed to control: opening the third valve leading to the third source to supply the second etchant into the reaction space, wherein the second etchant removes the non-Mo oxide layer from the substrate; and closing the third valve leading to the third source. In some embodiments, the controller may be further programmed to open the third valve leading to the third source and close the third valve leading to the third source after each closing of the second valve leading to the second source.

[0013] In some embodiments, the system is also configured to provide a continuous etchant to the reaction space before performing a cyclic etching process. In some embodiments, the controller may also be programmed to open a second valve to a second source and close the second valve to the second source before opening the first valve to the first source. In other embodiments, the system also includes a fourth source for providing a continuous etchant that is gaseously connected to the reaction space via a fourth valve, and the controller is also operably connected to the fourth valve and is configured and programmed to control: opening a fourth valve to the fourth source to supply a continuous etchant to the reaction space; and closing a fourth valve to the fourth source to stop the continuous etchant from flowing into the reaction space. In some embodiments, the controller may be further programmed to open a fourth valve to the fourth source and close a fourth valve to the fourth source before opening the first valve to the first source.

[0014] In some embodiments, the system further comprises at least one heating element in thermal communication with the substrate, and the controller is further operably connected to the at least one heating element and configured and programmed to control the temperature of the at least one heating element to maintain the temperature of the substrate at a set temperature.

[0015] In these aspects, in some embodiments, the oxygen-containing reactant is selected from oxygen (O2), ozone (O3), water (H2O), hydrogen peroxide (H2O2), organic peroxides, alcohols, nitrogen dioxide (NO2), nitrous oxide (N2O), nitric oxide (NO), nitrogen pentoxide (N2O5), pyridine oxide (C5H5NO), amine oxide, and combinations thereof. In some embodiments, the oxygen-containing reactant is selected from oxygen (O2), ozone (O3), nitrous oxide (N2O), and combinations thereof.

[0016] In these aspects, in some embodiments, the first etchant is selected from thionyl chloride (SOCl2), sulfonyl chloride (SO2Cl2), sulfur dichloride (S2Cl2), thionyl bromide (SOBr2), sulfonyl bromide (SO2Br2), sulfur dibromide (S2Br2), phosphorus pentachloride (PCl5), phosphorus trichloride (PCl3), phosphorus oxychloride (POCl3), phosphorus pentabromide (PBr5), phosphorus tribromide (PBr3), phosphorus oxybromide (POBr3), silicon tetrachloride (SiCl4), trichlorosilane (SiHCl3), dichlorosilane (SiH2Cl2), chlorosilane (SiH3Cl), hexachlorodisilane (Si2Cl6), silicon tetrabromide (SiBr4), tribromosilane (SiHBr3), dibromosilane (SiH2Br2), bromosilane (SiH3Br), hexabromodisilane (Si2Br6), and combinations thereof. In some embodiments, the first etchant is selected from SOCl2, PCl3, PCl5, SiCl4, and combinations thereof. In some embodiments, the first etchant is SOCl2.

[0017] In these aspects, in some embodiments, the oxygen-containing reactant is selected from oxygen (O2), ozone (O3), nitrous oxide (N2O), and combinations thereof, and the first etchant is selected from SOCl2, PCl3, PCl5, SiCl4, and combinations thereof. In some embodiments, the oxygen-containing reactant is selected from oxygen (O2), ozone (O3), nitrous oxide (N2O), and combinations thereof, and the first etchant is SOCl2. In some embodiments, the oxygen-containing reactant includes oxygen (O2), and the first etchant includes SOCl2. In some embodiments, the oxygen-containing reactant includes nitrous oxide (N2O), and the first etchant includes SOCl2.

[0018] In these aspects, in some embodiments, the volatile Mo-containing compound is molybdenum oxychloride or molybdenum oxybromide. In some embodiments, the volatile Mo-containing compound is molybdenum oxychloride.

[0019] In these aspects, in some embodiments, the substrate is maintained at a temperature of at least about 300° C. to no more than about 600° C. In some embodiments, the substrate is maintained at a temperature below about 450° C. In some embodiments, the substrate is maintained at a temperature below about 425° C. In some embodiments, the substrate is maintained at a temperature below about 400° C.

[0020] In these aspects, in some embodiments, the cyclic etching process is performed under thermal conditions in a plasma-free environment.

[0021] In these aspects, in some embodiments, the continuous etchant is selected from molybdenum pentachloride (MoCl5), thionyl chloride (SOCl2), sulfonyl chloride (SO2Cl2), sulfur dichloride (S2Cl2), thionyl bromide (SOBr2), sulfonyl bromide (SO2Br2), sulfur dibromide (S2Br2), phosphorus pentachloride (PCl5), phosphorus trichloride (PCl3), phosphorus oxychloride (POCl3), phosphorus pentabromide (PBr5), phosphorus tribromide (PBr3), phosphorus oxybromide (POBr3), silicon tetrachloride (SiCl4), trichlorosilane (SiHCl3), dichlorosilane (SiH2Cl2), chlorosilane (SiH3Cl), hexachlorodisilane (Si2Cl6), silicon tetrabromide (SiBr4), tribromosilane (SiHBr3), dibromosilane (SiH2Br2), bromosilane (SiH3Br), hexabromodisilane (Si2Br6), and combinations thereof. In some embodiments, the continuous etchant is selected from molybdenum pentachloride (MoCl5), thionyl chloride (SOCl2), phosphorus pentachloride (PCl5), phosphorus trichloride (PCl3), silicon tetrachloride (SiCl4) and combinations thereof. In some embodiments, the continuous etchant is thionyl chloride (SOCl2). In some embodiments, the continuous etchant is molybdenum pentachloride (MoCl5). In some embodiments, the continuous etchant is the same chemical compound as the first etchant.

[0022] In these aspects, in some embodiments, the substrate is maintained at a first temperature during the continuous etching steps and maintained at a second temperature during the cyclic etching process. In some embodiments, the first temperature is higher than the second temperature. In other embodiments, the first temperature is lower than the second temperature.

[0023] In these aspects, in some embodiments, the substrate includes at least one stack structure including a top and sidewalls formed by a plurality of stacked alternating material layers and a Mo outer layer located on the sidewalls of the stack structure. In some embodiments, the substrate includes at least one intermediate 3D NAND stack structure or at least one intermediate 3D DRAM stack structure. In some embodiments, the Mo outer layer is located on at least one sidewall of at least one intermediate 3D NAND stack structure or at least one intermediate 3D DRAM stack structure.

[0024] In these aspects, in some embodiments, the reaction space includes one or more reaction chambers of a semiconductor processing apparatus.

[0025] These and other embodiments will become apparent to those skilled in the art from the following detailed description of certain embodiments with reference to the accompanying figures.The present invention is not limited to any particular embodiment disclosed. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings constitute a part of the specification. The accompanying drawings are included to provide a further understanding of the present disclosure and to explain certain principles of the present disclosure together with the description. The accompanying drawings illustrate how to make and use exemplary embodiments of the present disclosure and should not be interpreted as limiting the present disclosure to only the examples shown and described. It should be understood that the elements in the accompanying drawings are shown for simplicity and clarity and are not necessarily drawn to scale. The illustrations presented herein are not meant to be actual views of any particular material, structure or device, but are merely idealized representations or illustrations for describing embodiments of the present disclosure. For example, the sizes of some elements in the figures may be exaggerated relative to other elements to help improve the understanding of the illustrated embodiments of the present disclosure. As shown in the accompanying drawings referenced below, further features and advantages will become apparent from the following more detailed description of various aspects, embodiments and configurations of the present disclosure.

[0027] Figure 1 is a process flow diagram of an exemplary embodiment of a cyclic etching process disclosed herein. Dashed lines illustrate optional steps.

[0028] Figure 2 is a process flow diagram of an exemplary embodiment of a cyclic etching process disclosed herein. Dashed lines illustrate optional steps.

[0029] Figure 3is a diagram of an embodiment of the etching sequence disclosed herein, wherein the etchant is SOCl2.

[0030] Figure 4 is a diagram of an embodiment of the etching sequence disclosed herein, wherein the etchant is PCl5.

[0031] Figure 5 is a diagram of an embodiment of the etching sequence disclosed herein, wherein the etchant is SiCl4.

[0032] Figure 6 is a process flow diagram of an exemplary embodiment of the present disclosure, wherein a continuous etching step is performed before a cyclic etching process. The dashed lines illustrate optional steps.

[0033] Figure 7 is a process flow diagram of an exemplary embodiment of the present disclosure, wherein a continuous etching step is performed before a cyclic etching process. The dashed lines illustrate optional steps.

[0034] Figure 8 is a schematic diagram of a semiconductor processing device according to an embodiment of the present disclosure.

[0035] Fig. 9A , Fig. 9B and Fig. 9C are illustrations of exemplary intermediate structures used to form interconnects at various stages of fabrication.

[0036] Fig. 10A , Fig. 10B and Fig. 10C is an illustration of an exemplary intermediate 3D NAND stack structure at various stages of fabrication.

[0037] Fig.11A , Fig. 11B and Fig. 11C is an illustration of an exemplary intermediate 3D DRAM stack structure at various stages of fabrication. DETAILED DESCRIPTION

[0038] The description of the embodiments of the methods, systems and structures provided below is exemplary only and is for illustrative purposes only. The following description is not intended to limit the scope of the present disclosure or the claims. In addition, the description of multiple embodiments with the features shown is not intended to exclude other embodiments with additional features or other embodiments incorporating different combinations of the features. Unless otherwise stated, the exemplary embodiments or their components may be combined or may be applied separately from each other. The titles provided here, if any, are only for convenience and do not necessarily affect the scope or meaning of the claimed invention.

[0039] definition

[0040] As used herein, "alkyl" refers to a functional group that can be derived from an alkane (e.g., an alkane with a hydrogen atom missing). An alkyl group can have a straight chain, branched chain, or cyclic structure. Generally, an alkyl group is part of a larger molecule, and the symbol "R" can be used to represent a general, unspecified alkyl group. In the case of a molecule having more than one R group, each R group can be independently selected. In some embodiments of the present disclosure, an alkyl group refers to a straight or branched C1 to C6 alkane (i.e., a C1 to C6 alkyl group) having one less hydrogen atom, such as a methyl group (—CH3), an ethyl group (—CH2CH3), a n-propyl group (—CH2CH2CH3), an isopropyl group (—CH(CH3)2), a n-butyl group (—CH2CH2CH2CH3), an isobutyl group (—CH2CH(CH3)CH3), a sec-butyl group (—CH(CH3)CH2CH3), a tert-butyl group (—C(CH3)3), a n-pentyl group (—CH2CH2CH2 CH2CH3), a 2-pentyl group (—CH(CH3)CH2CH2CH3), a 3-pentyl group (—CH2CH(CH3)CH2CH3), a neopentyl group (—CH2C(CH3)3), a tert-pentyl group (—C(CH3)2CH2CH3), an isopentyl group (—CH2 In some embodiments, the alkyl group refers to methyl (-CH3) or ethyl (-CH2CH3).

[0041] As used herein, an "anisotropic process" refers to a process that proceeds at a varying rate depending on the direction of the reaction space. For example, in anisotropic etching, etching may occur primarily in one direction on the substrate surface rather than another direction. In one such example, etching may occur primarily on the side surfaces of the substrate, without significantly occurring on the sidewalls of a recessed portion of the substrate.

[0042] As used herein, "aryl" refers to a functional group or substituent derived from an aromatic ring, typically an aromatic hydrocarbon. In general, an aryl group is part of a larger molecule, and the symbol "R" can be used to represent a general, unspecified aryl group. In the case of a molecule having more than one R group, each R group can be independently selected. In some embodiments of the present disclosure, aryl refers to phenyl (-C6H5).

[0043] As used herein, "atomic layer etching", abbreviated as "ALE", is a gas phase cyclic process that removes a thin layer or sublayer of material from the surface of a substrate using sequential reactions carried out in a reaction space (i.e., one or more reaction chambers). Typically, during each cycle in the ALE process, at least one reactant is introduced into the reaction space including the substrate to functionalize or chemically modify the top surface layer of the substrate. Thereafter, an etchant is introduced into the reaction space. The etchant reacts with the functionalized top layer to form volatile products, thereby removing material from the surface of the substrate. Typically, the etching step is self-limiting because excess etchant does react with the newly exposed non-functionalized surface, or does not react substantially. Other reaction steps may be included in the cyclic process as desired, for example, additional functionalization steps or etching steps may be included.

[0044] As used herein, a "cyclic etching process" refers to sequentially introducing reactants into a reaction space (ie, one or more reaction chambers) to etch at least a portion of a target surface, and includes processing techniques such as cyclic chemical vapor etching and ALE.

[0045] As used herein, "etchant" refers to a compound that participates in a surface chemical reaction to remove material from the surface. The chemical reaction may result in the formation of a volatile or gas phase reaction product that includes a portion of the surface material (eg, an element or radical of the surface material).

[0046] As used herein, "film" or "layer" used interchangeably refers to a continuous, substantially continuous or non-continuous material that extends in a direction perpendicular to the thickness direction to cover at least a portion of a surface. The film may be located on the side surfaces and / or sidewalls of a recessed feature of the surface. The thin film may include two-dimensional materials, three-dimensional materials, nanoparticles, partial or complete molecular layers, partial or complete atomic layers and / or atomic or molecular clusters. The film may be composed of one or more indistinguishable monolayers or sub-monolayers to produce a uniform or substantially uniform material, wherein the number of monolayers or sub-monolayers affects the thickness of the material.

[0047] As used herein, "gas" refers to a state of matter composed of atoms and / or molecules that has neither a definite volume nor a definite shape. Gases include evaporated solids and / or liquids and may consist of a single gas or a mixture of gases, depending on the context.

[0048] As used herein, "isotropic process" refers to a process that proceeds at substantially the same rate regardless of direction. For example, in isotropic etching, etching can occur in multiple directions on the substrate surface, such as on the side surfaces of the substrate and on the sidewalls of a recessed portion of the substrate.

[0049] As used herein, "molybdenum" or "Mo" refers to metallic molybdenum in the zero oxidation state. In some embodiments, Mo may include other elements as impurities, such as hydrogen, oxygen, carbon, nitrogen, and halogens. In some embodiments, molybdenum may have a purity of at least about 90% (by weight), or at least about 95%, or at least about 98%, or at least about 99%, or at least 99.5%, or at least about 99.9%.

[0050] As used herein, "molybdenum oxide" or "MoO x " refers to materials containing Mo-O bonds. Molybdenum oxide can be represented by the formula MoO x , where x is a variable that can vary from about 1 to about 3, typically from about 2 to about 3. x In the film, the variable x can be x The thickness of the layer varies, with x being closer to 3 at the surface of the layer than in the interior of the layer. It should be understood that the variable x may vary depending on the specific reactants and process conditions used to form the molybdenum oxide, as well as other factors, and may not be stoichiometric. MoO x The morphology can also vary and can be crystalline, with one or more phases, or it can be amorphous, depending on the x factors such as the specific reactants and process conditions.

[0051] As used herein, "molybdenum oxyhalide" or "MoO x X y " refers to a material containing Mo-O bonds and Mo-X bonds, wherein X is a halogen atom selected from chlorine (Cl), bromine (Br) or a combination thereof. Molybdenum oxyhalide can be represented by the formula MoO x X y , wherein x is a variable that can vary in the range of about 1 to about 2, and y is a variable that can vary in the range of about 1 to about 4. It should be understood that the variables x and y can vary depending on the specific reactants and process conditions used to form the molybdenum oxyhalide, as well as other factors. In some embodiments of the present disclosure, the molybdenum oxyhalide is molybdenum oxychloride (MoO x Cl y ), such as molybdenum oxytetrachloride (MoOCl4) and / or molybdenum dichloride (MoO2Cl2). In other embodiments, the molybdenum oxyhalide is molybdenum oxybromide (MoO x Br y ).

[0052] As used herein, "plasma" refers to an ionized gas that includes approximately equal amounts of negatively and positively charged species (usually electrons and ions). Excited and reactive species are also contained in the plasma, such as atoms and free radicals, metastable atoms and molecules, and photons. Plasma discharges require an applied electric or magnetic field to ionize the gas. Plasma generation schemes and geometries include, but are not limited to, capacitively coupled plasma (CCP), inductively coupled plasma (ICP), and RF hollow cathode (HC) plasmas, which differ in the generation of excited and reactive species, so they can provide different fluxes of different species.

[0053] As used herein, "purging" refers to clearing, removing or replacing certain gas phases and volatile substances from the reaction space. For example, purging can be performed by evacuating the reaction space with a vacuum pump and / or by replacing the gas in the reaction space with an inert or substantially inert gas such as argon or nitrogen. In some cases, the purging step can be implemented between two gas pulses that react with each other, or in other cases, the purging can be implemented between two gas pulses that do not react with each other. Purge can avoid or at least reduce the gas phase interaction between the two gases that react with each other. Purge can be used to remove volatile or gas phase reaction products from the substrate surface. It should be understood that purging can be performed in time or space, or both. For example, in the case of time purging, the purging step can be used in chronological order: a first reactant is provided to the reaction chamber, a purge gas is provided to the reaction chamber, and then a second reactant is provided to the reaction chamber, wherein the substrate on which the material is deposited or removed does not move. For example, in the case of a space purge, the purge step may include moving the substrate from a first position to a second position, a first reactant being continuously supplied to the first position, and a second reactant being continuously supplied to the second position through a purge gas curtain.

[0054] As used herein, "reactant" refers to a compound that participates in a chemical reaction to form another compound or element. In some cases, the reactant is an etchant. In other cases, the compound or element produced by the chemical reaction is non-volatile and / or it does not include a portion of the surface material (e.g., an element or group of the surface material), and thus the reactant is not an etchant.

[0055] As used herein, "substrate" refers to one or more underlying materials that can be used to form or on which a device, circuit, material or material layer can be formed. The substrate can be continuous or non-continuous; rigid or flexible; solid or porous; and combinations thereof. The substrate can be in any form, such as a powder, a plate or a workpiece. Plate-like substrates can include wafers of various shapes and sizes. The substrate can be made of semiconductor materials, including, for example, silicon, silicon germanium, silicon oxide, gallium arsenide, gallium nitride, and silicon carbide. The substrate can include one or more layers covering a bulk material, for example, the substrate can include nitrides, such as TiN, oxides, insulating materials, dielectric materials, conductive materials, metals, such as tungsten, ruthenium, molybdenum, cobalt, aluminum or copper, or other metallic materials, crystalline materials, epitaxial materials, heteroepitaxial materials and / or single crystal materials. The substrate can include various topological structures, such as gaps, recesses, lines, grooves, through holes, holes or spaces between raised portions, such as fins, etc., formed in or on at least a portion of a layer of the substrate.

[0056] As used herein, "volatile" refers to substances that easily change from a liquid or solid state to a gas phase. At a given temperature and pressure, volatile compounds or compounds with high volatility are more likely to exist as vapors; while non-volatile compounds or compounds with low volatility are more likely to be liquids or solids.

[0057] The articles "a" or "an" refer to one substance or a genus including a plurality of substances, depending on the context. Thus, the terms "a / an", "one or more" and "at least one" can be used interchangeably herein.

[0058] The terms "include", "comprising", and "having" are open ended and do not exclude the presence of other elements or components unless the context clearly indicates otherwise. Include, include, and have are used interchangeably and include the meaning of "consisting of". However, the phrase "consisting of" means that in addition to the mentioned features or components, there are no other features or components unless the context clearly indicates otherwise.

[0059] The term "about" applied to a value generally refers to a range of values ​​that are considered equivalent to the stated value (eg, having the same function or result). In some cases, the term "about" can include values ​​rounded to the nearest significant figure.

[0060] The term "substantially" as applied to a composition, method, or system generally means that the additional components do not substantially alter the properties and / or function of the composition, method, or system.

[0061] The term "on" or "above" can be used to describe a relative positional relationship. For example, an element, film or layer can be directly positioned on or above at least a portion of another element, film or layer and in physical contact with it; alternatively, an element, film or layer can be on or above another element, film or layer, but with one or more intervening elements, films or layers between them. Therefore, unless the term "directly" is also used, the term "on" or "above" will be interpreted as a relative concept. Similarly, it should be understood that the terms "below", "below" or "below" describe a relative positional relationship and should be interpreted as a relative concept unless otherwise stated.

[0062] The term "substantially" as applied to a composition, method or system generally refers to a proportion of at least about 70%, at least about 80%, at least about 90%, at least about 95%, at least about 97%, at least about 98%, at least about 99%, at least about 99.5%, at least about 99.9% or more, or any proportion between about 70% and about 100%. In some embodiments, the term "substantially" refers to a proportion of about 90%, about 95%, about 97%, about 98%, about 99%, about 99.5% or about 99.9%.

[0063] The terms "at least one", "one or more", and "and / or" are open-ended expressions that are both conjunctive and disjunctive in operation. For example, each of the expressions "at least one of A, B, and C", "at least one of A, B, or C", "one or more of A, B, and C", "one or more of A, B, or C", and "A, B and / or C" means A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B, and C together. When each of A, B, and C in the above expressions represents an element (e.g., X, Y, and Z) or a class of elements (e.g., X1-X n ,Y1-Y m and Z1-Z o ), the phrase is intended to mean a single element selected from X, Y and Z, a combination of elements selected from the same category (e.g., X1 and X2), and a combination of elements selected from two or more categories (e.g., Y1 and Z1).

[0064] It should be understood that each numerical range given throughout the disclosure is considered to include the upper and lower limits, as well as each narrower numerical range that falls within such broader numerical range, just as if such narrower numerical ranges were expressly written herein. For example, the phrase "from about 2 to about 4" or "from 2 to 4" includes 2 and 4, as well as integers and / or integer ranges from about 2 to about 3, from about 3 to about 4, and every possible range based on real numbers (e.g., irrational numbers and / or rational numbers), such as from about 2.1 to about 3.9, from about 2.1 to about 3.5, etc.

[0065] The present disclosure generally relates to methods and systems for etching molybdenum-containing films. In this context, a molybdenum-containing film is a film that contains molybdenum and may further contain additional elements, such as oxygen. In some embodiments, the molybdenum-containing film includes a bulk region that mainly contains metallic molybdenum and a bulk region that mainly contains molybdenum oxide (MoO x ) of an outer region or layer. It has been found that certain etchants can convert molybdenum oxide into volatile molybdenum-containing compounds, and under certain process conditions, this reactivity can be exploited to provide controlled etching of molybdenum-containing films. More specifically, the present invention generally relates to methods and systems for etching molybdenum (Mo) films using a cyclic etching process, wherein at least a portion of the molybdenum film is converted into molybdenum oxide, which then reacts with the etchant to form a volatile molybdenum-containing compound. In some embodiments, molybdenum etching can be advantageously performed using a simple two-step (i.e., two reactants) process under thermal conditions. Methods and systems for etching molybdenum can be used for various applications in the semiconductor industry, such as for manufacturing local interconnects in logic devices and 3D NAND and 3D DRAM structures in memory devices.

[0066] One aspect of the present disclosure relates to a method for etching a molybdenum-containing film. The method includes providing a substrate including a molybdenum-containing film in a reaction space (i.e., one or more reaction chambers) and exposing the substrate to an etchant to convert at least a portion of the molybdenum-containing film into a volatile molybdenum-containing compound. The molybdenum-containing film may include an outer region or layer located on a bulk region, wherein the outer layer includes molybdenum oxide (MoO x ), the bulk region includes metallic molybdenum. At least a portion of the outer layer is converted into a volatile molybdenum-containing compound, which is removed from the substrate surface, thereby reducing the thickness of the molybdenum-containing film.

[0067] More specifically, in some embodiments, a method for etching a molybdenum-containing film includes providing a substrate including a molybdenum (Mo) outer layer having an initial thickness in a reaction space (i.e., one or more reaction chambers), and exposing the substrate to an oxygen-containing reactant to convert at least a portion of the Mo outer layer into molybdenum oxide (MoO x Next, the substrate is exposed to an etchant to remove the MoO xThe reaction sequence is self-limiting because the removal of the volatile Mo-containing compound exposes a new outer layer (which may be Mo or another material) that does not react with the etchant or does not substantially react with the etchant under the process conditions (e.g., temperature and pressure) employed. This allows etching to be performed in a clear manner. Mo is removed layer by layer by repeating the reaction sequence during the cyclic etching process to remove the Mo outer layer of the target thickness from the substrate. As desired, other process steps may be optionally included in the reaction sequence, either before or after the reaction sequence, or before or after the cyclic etching process. For example, in some embodiments, a continuous etching step may be performed before the cyclic etching process. Exemplary embodiments and individual process steps and elements will be described in more detail below.

[0068] Figure 1 100 is a process flow diagram of an exemplary embodiment of a method for etching molybdenum disclosed herein. The method includes providing a substrate 101 including a Mo outer layer having an initial thickness in a reaction space, and performing a cyclic etching process 109. The cyclic etching process 109 includes: exposing the substrate to an oxygen-containing reactant 102, wherein the oxygen-containing reactant oxidizes at least a portion of the Mo outer layer into molybdenum oxide; optionally purging the reaction space 103; exposing the substrate to an etchant (also referred to as a first etchant in some places below) 104 to convert the molybdenum oxide into a volatile Mo-containing compound; and optionally purging the reaction space 105. Steps 102 and 104 can each be referred to as a sub-cycle, and together with the optional purge steps 103 and 105, they define an etching cycle of the cyclic etching process 109. The etching cycle can be repeated 107 (n times) to reduce the thickness of the Mo outer layer. As desired, other process steps can be optionally included in the etching cycle, or before or after the etching cycle, or before or after the cyclic etching process 109. For example, it will be appreciated that step 104 may be performed prior to step 102. Once a target thickness of molybdenum has been removed 106, the process terminates 108. The target thickness of molybdenum removed may be less than or equal to the initial thickness of the Mo outer layer.

[0069] Figure 2200 is a process flow diagram of another embodiment of a method for etching molybdenum disclosed herein. The method includes providing a substrate 201 including a Mo outer layer having an initial thickness in a reaction space, and performing a cyclic etching process 211. The cyclic etching process 211 includes: exposing the substrate to an oxygen-containing reactant 202, wherein the oxygen-containing reactant oxidizes at least a portion of the Mo outer layer to molybdenum oxide; optionally purging the reaction space 203; exposing the substrate to a first etchant 204 to convert the molybdenum oxide into a volatile Mo-containing compound; optionally purging the reaction space 205; exposing the substrate to a second etchant to remove a Mo-free oxide layer 206 from the substrate surface; and optionally purging the reaction space 207. Steps 202, 204, and 206 can each be referred to as a sub-cycle, and together with the optional purge steps 203, 205, and 207, they define an etching cycle of the cyclic etching process 211. The etching cycle can be repeated 209 (n times) to reduce the thickness of the Mo outer layer. As desired, other process steps may optionally be included during the etching cycle, or before or after the etching cycle, or before or after the cyclic etching process 211. For example, it will be appreciated that steps 204 and 206 may be performed before step 202. Once the target thickness of molybdenum has been removed, the process terminates 210. The target thickness of molybdenum removed is less than or equal to the initial thickness of the outer layer of molybdenum.

[0070] In an embodiment of the present disclosure, in a reaction space (e.g., one or more reaction chambers) (e.g., see Figure 1 101 and Figure 2 201 in ) provides a substrate including a Mo outer layer. The reaction space is not particularly limited and may include one or more reaction chambers of a semiconductor processing device. In some embodiments, one or more reaction chambers in a flow-type reactor may be utilized. In some embodiments, one or more reaction chambers in a showerhead reactor may be utilized. In some embodiments, one or more reaction chambers in a space-separated reactor may be utilized. In some embodiments, one or more reaction chambers in a single-wafer reactor with high-capacity manufacturing capabilities may be utilized. In other embodiments, one or more reaction chambers in a batch reactor may be utilized. For embodiments using a batch reactor, the reaction chamber may accommodate many wafers, for example, the number of wafers may be in the range of 10 to 200, or 50 to 150, or even 100 to 150. In any of these embodiments, the reactor may be configured as a thermal reactor, and a plasma generation unit may be lacking or not used.

[0071] The substrate is not particularly limited either, and may be a semiconductor wafer (or multiple semiconductor wafers). In addition to the Mo outer layer, the substrate may include one or more material layers, such as a dielectric layer, an insulating layer, a conductive layer, a sacrificial layer, etc. The substrate may include various topological features, such as spaces between raised portions formed in or on at least a portion of a layer of the substrate, such as gaps, depressions, lines, grooves, through holes, holes, or on. The Mo outer layer may cover the entire surface of the substrate or only a portion of the substrate, and may be present on the side surfaces and / or vertical surfaces or sidewalls of various topological features. Portions of the Mo outer layer may be covered with a mask layer, while other portions may be exposed.

[0072] In some embodiments, the substrate includes: at least one stacked structure formed by a plurality of stacked alternating material layers, at least one stacked structure including a top and sidewalls; and a Mo outer layer located on at least a portion of the sidewalls or at least one sidewall of the stacked structure, and optionally located on at least a portion of the top of the stacked structure. At least one stacked structure may include a plurality of stacked alternating insulating layers (e.g., silicon oxide) and conductive layers (e.g., molybdenum). (An exemplary embodiment of such a structure is shown in FIG. Fig. 10B , which will be described in more detail below. ) At least one stacked structure may include a plurality of stacked alternating insulating layers (e.g., silicon oxide), channel layers, and conductive layers (e.g., molybdenum). (An exemplary embodiment of such a structure is shown in Fig. 11B , which will be described in more detail below. ) In some embodiments, the stacked structure can be an intermediate 3D NAND stack or an intermediate 3D DRAM stack. In this article, "intermediate" refers to a partially formed structure that requires further production steps to form the final structure.

[0073] The substrate including the Mo outer layer is exposed to an oxygen-containing reactant to convert at least a portion of the Mo outer layer into molybdenum oxide (MoO x )(See for example Figure 1 102 and Figure 2 202 in the figure). Oxidation of the Mo outer layer increases the reactivity of the outer layer, enabling the subsequent etching step. The oxidation may be effected by thermal or plasma methods. In either case, an oxygen-containing reactant is introduced into the reaction space and the Mo outer layer is contacted with the oxygen-containing reactant. The degree of oxidation (i.e., MoO xThe value of x in () and the thickness of the oxide layer depend on factors such as the nature of the oxygen-containing reactant, the flow rate of the oxygen-containing reactant on the substrate surface, and the time the substrate is exposed to the oxygen-containing reactant. For example, certain oxygen-containing reactants can penetrate or diffuse into the substrate surface to varying degrees, thereby oxidizing more than just the outermost atomic or molecular layer. Higher flow rates and longer exposure times of oxygen-containing reactants will increase the thickness of the oxide layer and the degree of oxidation, and the degree of oxidation will vary with the thickness of the oxide layer. The thickness of the oxide layer will affect the amount of material removed in subsequent etching steps; therefore, these variables can be used to adjust the etching rate of the process. In different embodiments of the present disclosure, the pulse time for introducing the oxygen-containing reactant into the reaction space can vary. Typical pulse times for introducing the oxygen-containing reactant into the reaction space are from about 0.1 seconds to about 10 minutes, typically from about 1 second to about 3 minutes, or from about 1 second to about 1 minute, after which the reaction space can optionally be rinsed or purged to remove unreacted oxygen-containing reactants and other applicable substances from the reaction space (see, for example Figure 1 103 and Figure 2 203).

[0074] In some embodiments, the Mo outer layer is oxidized under thermal conditions. Under thermal conditions, the reaction can be promoted by increasing the temperature relative to the ambient temperature. Generally, the increase in temperature provides the energy required for the reaction in the absence of other external energy sources such as plasma, free radicals or other forms of radiation. In other words, the reaction does not use active substances generated by plasma, so it can be called "plasma-free". In the case of isotropic etching and / or forming a high aspect ratio structure, a thermal method may be preferred. Suitable oxygen-containing reactants include but are not limited to oxygen (O2), ozone (O3), water (H2O), hydrogen peroxide (H2O2), organic peroxides (ROOH, where R is an alkyl or aryl group), alcohols (ROH, where R is an alkyl or aryl group), nitrogen dioxide (NO2), nitrous oxide (N2O), nitric oxide (NO), nitrogen pentoxide (N2O5), pyridine oxide (C5H5NO), amine oxide (R3NO, where each R is independently an alkyl or aryl group), and / or two or more R groups can be bonded to each other to form a ring structure), and combinations thereof. In some embodiments, the oxygen-containing reactant is oxygen, ozone, nitrous oxide, or a combination thereof. In some embodiments, the oxygen-containing reactant is free of plasma species, and the substrate is not exposed to plasma species. For example, the oxygen-containing reactant may be free of one or more of ionic species, free radical species, atoms, metastable species, and excited species.

[0075] In other embodiments, the Mo outer layer is oxidized under non-thermal conditions using plasma. For applications requiring lower temperatures and / or applications requiring anisotropic etching, plasma-based methods may be preferred. In these embodiments, oxygen-containing reactants are formed by providing an oxygen-containing feed gas to a plasma source. The plasma source can be a direct plasma source or a remote plasma source. In different embodiments of the present disclosure, the power used to generate the plasma can vary. In some embodiments, the power used to generate the plasma is from about 10W to about 2000W, typically from about 20W to about 1000W, or more typically from about 20W to about 500W. Suitable oxygen-containing feed gases include, but are not limited to, oxygen (O2), ozone (O3), water (H2O), hydrogen peroxide (H2O2), organic peroxides (ROOH, wherein R is alkyl or aryl), alcohols (ROH, wherein R is alkyl or aryl), nitrogen dioxide (NO2), nitrous oxide (N2O), nitric oxide (NO), nitrogen pentoxide (N2O5), pyridine oxide (C5H5NO), amine oxide (R3NO, wherein each R is independently alkyl or aryl), and / or two or more R groups may be bonded to each other to form a ring structure), and combinations thereof. Thus, the oxygen-containing reactant may include O2, O3, H2O, H2O2, ROOH, ROH, NO2, N2O, NO, N2O5, C5H5NO, R3NO, combinations thereof, and oxygen plasma species formed thereby. In some embodiments, the oxygen-containing reactant includes an oxygen plasma species. In some embodiments, the oxygen-containing reactant is an oxygen plasma species. Examples of oxygen plasma species include, but are not limited to, atomic oxygen (O), excited diatomic oxygen (e.g., singlet oxygen ( 1 Oxygen-containing feed gases may be optionally mixed or co-fed with a carrier gas, such as an inert gas selected from helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and mixtures thereof. In some cases, excited species from the inert gas in the plasma may help promote the reaction, as well as aid in the formation and ignition of the plasma.

[0076] The substrate is exposed to an etchant (also referred to as a first etchant in some places herein) (see, e.g. Figure 1 104 and Figure 2 204 in the figure). The exposure of the substrate to the etchant occurs under thermal conditions; therefore, the etchant does not contain plasma species and the substrate is not exposed to plasma species. The etchant converts MoO x The outer layer is converted into a volatile Mo-containing compound, which is removed from the substrate surface. In some embodiments, the volatile Mo-containing compound is a molybdenum oxyhalide (MoO x X yFor example, in some embodiments, the volatile Mo-containing compound may be molybdenum oxychloride (MoO x Cl y ), such as molybdenum oxychloride tetrachloride (MoOCl4) (melting point = 101°C) and / or molybdenum dichloride dioxide (MoO2Cl2) (melting point = 175°C), both of which can be easily removed from the substrate surface. In addition to MoOCl4 and MoO2Cl2, or as an alternative, other oxychlorides can be formed. In other embodiments, the volatile Mo-containing compound can be molybdenum oxybromide (MoO x Br y ).

[0077] Many suitable etchants can be used, as long as the etchant is compatible with MoO x The reaction is favorable and results in the formation of volatile Mo-containing compounds. In general, if the Gibbs free energy change of the reaction is negative (i.e., Δ rnx G(T) < 0), then the reaction can be considered favorable. The free energy change of a given reaction is a function of temperature (T). The substrate temperature is usually maintained so that the etchant and MoO xThe reaction of is spontaneous, while the reaction of the etchant with Mo is not spontaneous. In some embodiments, the etchant includes one or more sulfur-chlorine bonds (i.e., S-Cl bonds) and / or one or more sulfur-bromine bonds (i.e., S-Br bonds). Suitable etchants containing S-Cl bonds may include, but are not limited to, sulfuryl chloride (SOCl2), sulfonyl chloride (SO2Cl2), sulfur dichloride (S2Cl2). Suitable etchants containing S-Br bonds may include, but are not limited to, thionyl bromide (SOBr2), sulfonyl bromide (SO2Br2), sulfur dibromide (S2Br2). In some embodiments, the etchant includes one or more phosphorus-chlorine bonds (i.e., P-Cl bonds) and / or one or more phosphorus-bromine bonds (i.e., P-Br bonds). Suitable etchants containing P-Cl bonds may include, but are not limited to, phosphorus pentachloride (PCl5), phosphorus trichloride (PCl3), and phosphorus oxychloride (POCl3). Suitable etchants containing P-Br bonds may include, but are not limited to, phosphorus pentabromide (PBr5), phosphorus tribromide (PBr3), and phosphorus bromide (POBr3). In some embodiments, the etchant includes one or more silicon-chlorine bonds (i.e., Si-Cl bonds) and / or one or more silicon-bromine bonds (i.e., Si-Br bonds). Suitable etchants containing Si-Cl bonds may include, but are not limited to, silicon tetrachloride (SiCl4), trichlorosilane (SiHCl3), dichlorosilane (SiH2Cl2), chlorosilane (SiH3Cl) and hexachlorodisilane (Si2Cl6). Suitable etchants containing Si-Br bonds may include, but are not limited to, silicon tetrabromide (SiBr4), tribromosilane (SiHBr3), dibromosilane (SiH2Br2), bromosilane (SiH3Br) and hexabromodisilane (Si2Br6). The etchant may be in gaseous form, or it may have sufficient vapor pressure at room temperature or near room temperature, or above room temperature, so that it is transported to the reaction space and the substrate surface. The etchant may be heated to provide sufficient vapor pressure and / or be entrained by an inert carrier gas flow (e.g., nitrogen and / or rare gases, such as helium (He) and argon (Ar)) and introduced into the reaction space. The flow rate and / or pulse time of the etchant into the reaction space can be optimized to make MoO x The outer layer is completely removed from the substrate surface. Typical pulse times for introducing the etchant into the reaction space range from about 0.1 seconds to about 10 minutes, typically from about 1 second to about 3 minutes, or from about 1 second to about 1 minute, after which the reaction space can be optionally rinsed or purged to remove unreacted etchant and reaction byproducts, such as volatile Mo-containing species (see, for example, Figure 1 105 and Figure 2 205).

[0078] In an exemplary embodiment of the present disclosure, the etchant includes thionyl chloride (SOCl2). In some embodiments, the etchant is SOCl2. The boiling point of thionyl chloride is 74.6°C and the vapor pressure at 25°C is 15.7 kPa. Without wishing to be bound by a particular mechanism, it is assumed that when the etchant is SOCl2, the etching cycle is as follows: Figure 3 In a first step, a structure 301 including a substrate including a Mo outer layer having a first thickness 304 is exposed to an oxygen-containing reactant (e.g., O2 and / or O3, although other oxygen-containing reactants may be used) to convert at least a portion of the Mo outer layer into MoO x The resulting structure 302 includes a molybdenum-containing film including a MoO-containing layer disposed on a bulk region including metallic molybdenum (Mo). x Next, the structure 302 is exposed to SOCl2. The reaction product MoO x Cl y and SO2 are removed from the substrate surface by diffusion and / or purging to expose a structure 303 including an outer layer of Mo having a second thickness less than the first thickness 306. The process may be repeated (e.g., as Figure 1 109 in the figure) to remove a target thickness of molybdenum 305 from the surface of the substrate.

[0079] In another exemplary embodiment of the present disclosure, the etchant includes phosphorus pentachloride (PCl5). In some embodiments, the etchant is PCl5. Phosphorus pentachloride is a yellow-white solid that sublimes at 166.8°C and has a vapor pressure of 4.58 kPa at 100°C. Without wishing to be bound by a particular mechanism, it is assumed that when the etchant is PCl5, the etching cycle is as follows: Figure 4 In a first step, a structure 401 including a substrate including a Mo outer layer having a first thickness 404 is exposed to an oxygen-containing reactant (e.g., O2 and / or O3, although other oxygen-containing reactants may be used) to convert at least a portion of the Mo outer layer into MoO x The resulting structure 402 includes a molybdenum-containing film including a MoO-containing layer disposed on a bulk region including metallic molybdenum (Mo). x Next, the structure 402 is exposed to PCl5 to form MoO x The layer is converted into volatile MoO x Cl y The reaction also produces a volatile phosphorus-containing compound, which can generally be represented by P a O b Cl c , where the subscripts "a", "b", and "c" are integers indicating that the stoichiometry may vary. a O b Cl cIt can be any one of POCl3, P2O5 and / or P4O6. The reaction product MoO x Cl y and P a O b Cl c The substrate is removed by diffusion and / or purging to expose a structure 403 including an outer layer of Mo having a second thickness 406 less than the initial thickness 404. The process may be repeated (e.g., Figure 1 109 in the figure) to remove a target thickness of molybdenum from the surface of the substrate 405.

[0080] In yet another exemplary embodiment of the present disclosure, the etchant is silicon tetrachloride (SiCl4). In some embodiments, the etchant is SiCl4. Silicon tetrachloride has a boiling point of 57.65°C and a vapor pressure of 25.9 kPa at 20°C. Without wishing to be bound by a particular mechanism, it is assumed that when the etchant is SiCl4, the etching cycle is as follows Figure 5 In a first step, a structure 501 including a substrate including a Mo outer layer having a first thickness 505 is exposed to an oxygen-containing reactant (e.g., O2 and / or O3, although other oxygen-containing reactants may be used) to convert at least a portion of the Mo outer layer into MoO x The resulting structure 502 includes a molybdenum-containing film including a MoO-containing layer disposed on a bulk region including metallic molybdenum (Mo). x Next, the structure 502 is exposed to SiCl4 to convert the MoO x The layer is converted into volatile MoO x Cl y The reaction also produces SiO2 as a solid layer on the substrate surface 503 (shown in structure 503), and a second etching step is required to expose structure 504 including an outer layer of Mo having a second thickness less than the initial thickness 507. For example, SiO2 can be easily removed by exposing the substrate to HF. The process can be repeated (e.g., as Figure 2 211 in the figure) to remove a target thickness of molybdenum from the surface of the substrate 506.

[0081] The various process steps of the etching cycle discussed above can be repeated sequentially to remove a target thickness of molybdenum from the substrate surface. Figure 1In the embodiment shown, the method may include repeating 107 steps 102 and 104 one or more times (n) to remove a target thickness of molybdenum from the substrate surface; or repeating 107 steps 102, 103, 104 and 105 one or more times (n) to remove a target thickness of molybdenum from the substrate surface; or repeating 107 steps 102, 103 and 104 or steps 102, 104 and 105 one or more times (n) to remove a target thickness of molybdenum from the substrate surface; or any combination thereof. In another example, referring to Figure 2 In the illustrated embodiment, the method may include repeating 209 steps 202, 204 and 206 one or more times (n) to remove a target thickness of molybdenum from the surface of the substrate; or repeating 209 steps 202, 203, 204, 205, 206 and 207 one or more times (n) to remove a target thickness of molybdenum from the surface of the substrate; or repeating 209 steps 202, 204 and 206 (with any steps 203, 205 and 207) one or more times (n) to remove a target thickness of molybdenum from the surface of the substrate; or any combination thereof. Other steps may be inserted into the process as desired. For example, other reaction steps and / or etching steps may be performed before, after or between the n repeated cycles. The number of repeated cycles (n) is not particularly limited and depends on the target Mo thickness to be removed and the etching rate of molybdenum. In some embodiments, the Mo outer layer is about to about / etching cycle rate etching, for example about to about / the rate of the etching cycle, or even about to about / etching cycle rate. In some embodiments, the Mo outer layer is about to about / etch cycle rate, or at about to about / etch cycle rate, or at about to about / etching cycle. In some embodiments, the process is repeated until the Mo outer layer of the target thickness is removed. In some embodiments, the process is repeated until the entire Mo outer layer has been removed. In some embodiments, the Mo outer layer may have an initial thickness (pre-etch) of between about 0.5 nm and about 20 nm, or between about 2 nm and about 15 nm, or between about 4 nm and about 15 nm. In some embodiments, the Mo outer layer may have an initial thickness (pre-etch) of less than about 20 nm, or less than about 15 nm, or less than about 12 nm, or less than about 10 nm, or less than about 8 nm, or less than about 4 nm, or less than about 2 nm. In some embodiments, the number of repeated cycles (n) is from about 1 to about 5000, from about 1 to about 2000, from about 1 to about 1000, from about 1 to about 500, from about 1 to about 200, from about 1 to about 100, or typically from about 10 to about 1000, typically from about 10 to about 500, typically from about 10 to about 200, typically from about 10 to about 100, or more typically between about 50 and about 1000, or more typically between about 50 and about 500, or more typically between about 50 and about 200.

[0082] In certain embodiments, a continuous etching step is performed before the above-mentioned cyclic etching process. In these embodiments, the continuous etching step is used to reduce the thickness of the Mo outer layer to an intermediate thickness, and then the cyclic etching process is used to further reduce the thickness of the Mo outer layer to a final thickness or completely remove the Mo outer layer. The use of the continuous etching step allows molybdenum to be quickly removed without the need to sequentially introduce multiple reactants into the reaction space; and the cyclic etching process allows the removal of molybdenum in a clear and controlled manner. The continuous etching step can be performed by exposing a substrate including a Mo outer layer having an initial thickness to a continuous etchant, thereby reducing the thickness of the Mo outer layer to an intermediate thickness. The amount of molybdenum removed (i.e., the difference between the initial thickness and the intermediate thickness) depends on factors such as the properties of the continuous etchant, the flow rate of the continuous etchant to the substrate surface, and the time when the substrate surface is exposed to the continuous etchant. In some embodiments, the Mo outer layer may have an initial thickness (pre-etching) between about 5nm and about 20nm, and the thickness of the Mo outer layer is reduced to an intermediate thickness of less than about 10nm, or less than about 5nm, or less than about 3nm using a continuous etching step. In some embodiments, the Mo outer layer may have an initial thickness (pre-etch) between about 5 nm and about 15 nm, and successive etching steps are used to reduce the thickness of the Mo outer layer to an intermediate thickness of less than about 10 nm, or less than about 5 nm, or less than about 3 nm.

[0083] Figure 6 A process diagram 600 of an exemplary embodiment of the present disclosure is shown, wherein a continuous etching step 602 is performed before a cyclic etching process 611. (Note that Figure 6 Steps 604 to 611 in FIG. Figure 1) The method includes: providing a substrate 601 including a Mo outer layer having an initial thickness in a reaction space; exposing the substrate to a continuous etchant 602 to reduce the thickness of the Mo outer layer to an intermediate thickness; optionally purging the reaction space 603; and performing a cyclic etching process 611. The cyclic etching process 611 includes: exposing the substrate to an oxygen-containing reactant 604, wherein the oxygen-containing reactant oxidizes at least a portion of the Mo outer layer having an intermediate thickness into molybdenum oxide; optionally purging the reaction space 605; exposing the substrate to an etchant (also referred to as a first etchant in some places of the present disclosure) 606 to convert the molybdenum oxide into a volatile Mo-containing compound; and optionally purging the reaction space 607. Step 602 is a continuous etching process. Steps 604 to 607 define one etching cycle of the cyclic etching process 611. The etching cycles 604 to 606 and the optional purging steps 605 and 607 can be repeated 609 (n times) to reduce the thickness of the Mo outer layer. Once a target thickness of Mo has been removed 608, the process terminates 610. The target thickness of Mo removed may be less than or equal to the initial thickness of the Mo outer layer.

[0084] Figure 7 A process diagram 700 of another exemplary embodiment of the present disclosure is shown, wherein a continuous etching step 702 is performed before a cyclic etching process 713. (Note that Figure 7 Steps 704 to 713 in Figure 2 ) The method comprises: providing a substrate 701 including a Mo outer layer having an initial thickness in a reaction space; exposing the substrate to a continuous etchant 702 to reduce the thickness of the Mo outer layer to an intermediate thickness; optionally purging the reaction space 703; and performing a cyclic etching process 713. The cyclic etching process 713 comprises: exposing the substrate to an oxygen-containing reactant 704, wherein the oxygen-containing reactant oxidizes at least a portion of the Mo outer layer having an intermediate thickness into molybdenum oxide; optionally purging the reaction space 705; exposing the substrate to a first etchant 706 to convert the molybdenum oxide into a volatile Mo-containing compound; optionally purging the reaction space 707; exposing the substrate to a second etchant to remove a Mo-free oxide layer 708 from the substrate surface; and optionally purging the reaction space 709. Step 702 is a continuous etching process. Steps 704, 706, and 708 together with the optional purge steps 705, 707, and 709 define one etching cycle of the cyclic etching process 713. The etching cycles 704 to 709 may be repeated 711 (n times) to reduce the thickness of the Mo outer layer. Once a target thickness of molybdenum has been removed 710, the process terminates 712. The target thickness of the removed molybdenum may be less than or equal to the initial thickness of the Mo outer layer.

[0085] Suitable continuous etchants include, but are not limited to, molybdenum pentachloride (MoCl5), thionyl chloride (SOCl2), sulfonyl chloride (SO2Cl2), sulfur dichloride (S2Cl2), thionyl bromide (SOBr2), sulfonyl bromide (SO2Br2), sulfur dibromide (S2Br2), phosphorus pentachloride (PCl5), phosphorus trichloride (PCl3), phosphorus oxychloride (POCl3), phosphorus pentabromide (PBr5), phosphorus tribromide (PBr3), phosphorus oxybromide (POBr3), silicon tetrachloride (SiCl4), trichlorosilane (SiHCl3), dichlorosilane (SiH2Cl2), chlorosilane (SiH3Cl), hexachlorodisilane (Si2Cl6), silicon tetrabromide (SiBr4), tribromosilane (SiHBr3), dibromosilane (SiH2Br2), bromosilane (SiH3Br), hexabromodisilane (Si2Br6), and combinations thereof. In some embodiments, the continuous etchant includes molybdenum pentachloride (MoCl5), which spontaneously etches molybdenum at room temperature and above. In some embodiments, the continuous etchant is MoCl5. In other embodiments, the continuous etchant and the first etchant are the same chemical compound, and the continuous etching step and the cyclic etching process are performed under different reaction conditions, so that the outer layer of Mo is etched in the continuous etching step, but not or substantially not etched in the cyclic etching process. For example, during the continuous etching process, the substrate can be maintained at a first temperature so that the reaction of the etchant with Mo is spontaneous, and during the cyclic etching process, the substrate can be maintained at a second temperature so that the etchant reacts with Mo. x The reaction of is spontaneous, but the reaction of the etchant with Mo is not spontaneous. Typically, in these embodiments, the first temperature is higher than the second temperature. In some of these embodiments, the continuous etchant includes SOCl2. In some of these embodiments, the continuous etchant is SOCl2. In some of these embodiments, the continuous etchant and the first etchant are SOCl2. In some of these embodiments, the continuous etchant includes one or both of PCl5 and PCl3. In some of these embodiments, the continuous etchant is one or both of PCl5 and PCl3. In some of these embodiments, the continuous etchant and the first etchant are one or both of PCl5 and PCl3. In some of these embodiments, the continuous etchant includes SiCl4. In some of these embodiments, the continuous etchant is SiCl4. In some of these embodiments, the continuous etchant and the first etchant are SiCl4.

[0086] As known to those skilled in the art, many process parameters can affect the etching rate of the outer layer of Mo. These process parameters include, but are not limited to, substrate temperature, pressure inside the reaction space, time for the substrate surface to be exposed to oxygen-containing reactants and etchants, flow rates of oxygen-containing reactants and etchants to the substrate surface, etc. Based on routine work, these parameters can be optimized to obtain a suitable etching rate, and such optimization is within the capabilities of those skilled in the art.

[0087] The method according to the present disclosure can be carried out at an elevated temperature. For example, the substrate can be maintained at an elevated temperature. In some embodiments, the method is performed by maintaining the substrate temperature at a temperature of about 40°C to about 600°C, typically about 100°C to about 500°C, or about 100°C to about 475°C, or about 100°C to about 450°C, or about 100°C to about 425°C, or about 100°C to about 400°C, or about 100°C to about 375°C, or about 100°C to about 350°C, or about 100°C to about 325°C, or about 100°C to about 300°C, or about 100°C to about 275°C, or about 100°C to about 250°C. In some embodiments, the method is performed by maintaining the substrate temperature at less than about 450°C, or less than about 425°C, or less than about 400°C. In some embodiments, the method is performed by maintaining the substrate temperature at about 50°C, or about 75°C, or about 100°C, or about 125°C, or about 150°C, or about 175°C, or about 200°C, or about 225°C, or about 250°C, or about 275°C, or about 300°C, or about 325°C, or about 350°C, or about 375°C, or about 400°C, or about 425°C, or about 450°C, or about 475°C, or about 500°C, or about 525°C, or about 550°C, or about 575°C, or about 600°C. In some embodiments, the method is performed under thermal conditions (i.e., the substrate is not exposed to plasma species), and the substrate temperature may be maintained at a temperature from about 300°C to about 600°C, typically from about 300°C to about 450°C, or from about 300°C to about 425°C, or from about 300°C to about 400°C. In other embodiments, the substrate is exposed to oxygen plasma species, and the substrate temperature may be maintained at a temperature from about 100°C to about 400°C, typically from about 100°C to about 300°C, or more typically from about 100°C to about 250°C. In certain embodiments, a continuous etching step is performed prior to the cyclic etching process, and the substrate may be maintained at a first temperature during the continuous etching step and at a second temperature during the cyclic etching process. In some of these embodiments, the first temperature may be higher than the second temperature. In some other embodiments of these embodiments, the first temperature may be lower than the second temperature.

[0088] The method according to the present invention can be carried out under reduced pressure. In some embodiments, the pressure in the reaction space during the etching process is less than about 500 Torr, usually from about 0.1 Torr to about 500 Torr, or from about 0.5 Torr to about 100 Torr, or from about 1 Torr to about 20 Torr. In some embodiments, the pressure in the reaction space during the etching process is less than about 100 Torr, less than about 50 Torr, less than about 20 Torr or less than about 10 Torr. In some embodiments, the pressure in the reaction space during the etching cycle is lower than about 20 Torr. In some embodiments, the pressure in the reaction space during the etching cycle is lower than about 10 Torr. In some embodiments, the pressure in the reaction space during the etching cycle is higher than about 1 Torr. In some embodiments, the pressure in the reaction space during the etching cycle is higher than about 5 Torr. In some embodiments, the pressure in the reaction space during the etching process is between about 1 Torr and about 25 Torr. In some embodiments, the process can be carried out under constant pressure. In some embodiments, the pressure in the reaction space during the first sub-cycle is different from the pressure in the reaction chamber during the second sub-cycle or the third sub-cycle. For example, the first pressure in the reaction space during the oxidation reaction can be higher than the second pressure in the reaction space during the etching reaction step. Alternatively, the first pressure in the reaction space during the oxidation reaction may be lower than the second pressure in the reaction space during the etching reaction step. In other cases, the first pressure in the reaction space during the oxidation reaction may be the same or substantially the same as the second pressure in the reaction space during the etching reaction step. In certain embodiments in which continuous etching steps are performed, the pressure in the reaction space during the continuous etching steps may be different from the pressure in the reaction chamber during the cyclic etching process. For example, the first pressure in the reaction space during the continuous etching steps may be higher than the second pressure in the reaction space during the cyclic etching process. Alternatively, the first pressure in the reaction space during the continuous etching steps may be lower than the second pressure in the reaction space during the cyclic etching process. In other cases, the first pressure in the reaction space during the continuous etching steps may be the same or substantially the same as the second pressure in the reaction space during the cyclic etching process.

[0089] Another aspect of the present disclosure relates to a system for etching a molybdenum-containing film using the method disclosed herein. In some embodiments, the system is a semiconductor processing device including a reaction space (i.e., at least one reaction chamber), and the reaction space is used to accommodate a substrate including a Mo outer layer. The semiconductor processing device may include one reaction chamber, two reaction chambers, three reaction chambers, four reaction chambers or more. In some embodiments, one or more reaction chambers in a flow-type reactor can be utilized. In some embodiments, one or more reaction chambers in a showerhead reactor can be utilized. In some embodiments, one or more reaction chambers in a space-separated reactor can be utilized. In some embodiments, one or more reaction chambers in a single-wafer reactor with high-volume manufacturing capabilities can be utilized. In other embodiments, one or more reaction chambers in a batch reactor can be utilized. The semiconductor processing equipment also includes a substrate for exposing it to an oxygen-containing reactant to convert at least a portion of the Mo outer layer into molybdenum oxide (MoO x ) and a device for exposing a substrate to an etchant to convert MoO x The semiconductor processing equipment may further include one or more of a device for exposing the substrate to additional reactants and a device for heating the substrate. In some embodiments, the semiconductor processing equipment also includes a device for generating plasma. In other embodiments, the semiconductor processing equipment does not include a device for generating plasma. These different elements and how they are related to the disclosed method are described in detail above.

[0090] Figure 8A schematic diagram of an exemplary embodiment of a semiconductor processing apparatus 800 according to the present disclosure is shown. Gaseous reactants are provided into a reaction chamber 801 through an injector system 802. The injector system 802 is configured to provide an oxygen-containing reactant from a first source 803, a first etchant from a second source 804, optionally a second etchant from a third source 805, and optionally a continuous etchant from a fourth source 806. The injector system may further include one or more other gas sources (not shown), such as for providing a purge gas and a carrier gas (e.g., nitrogen and / or a noble gas, such as He, Ne, Ar, Kr, Xe, and combinations thereof) to the reaction chamber, and a device for heating the various reactant sources and corresponding gas lines, if necessary, to facilitate their introduction into the reaction chamber 807. The various gases flow into the reaction chamber 801 through a showerhead 810, which is located directly above a susceptor 812, on which a substrate 811 is placed. In some embodiments, the reaction chamber 801 may further include one or more heating elements (not shown) that are thermally connected to the substrate 811 and one or more thermocouples (not shown) to maintain the temperature of the substrate 811 at a set temperature. Unreacted gases and gaseous reaction byproducts leave the reaction chamber 801 through an exhaust pipe 813 connected to a vacuum pump 814. Optionally, in certain embodiments, the semiconductor processing equipment 800 also includes a plasma unit, which includes a plasma generator (e.g., an RF power generator or a microwave power generator) (not shown), which can be configured to form plasma between the showerhead 810 and the susceptor 812, or alternatively, to form plasma remotely upstream of the reaction chamber 801. The semiconductor processing equipment also includes a controller 815 operably connected to the first, second, third and fourth valves 807-810 and other components (not shown). The controller 815 is configured and programmed to independently control (e.g., turn on and off, etc.) the supply of various gases (e.g., oxygen-containing reactants, first etchant and optional second etchant, continuous etchant, carrier gas and purge gas, etc.), the plasma generator (if present), and other components to etch the Mo outer layer.

[0091] In some embodiments, the controller 815 is configured and programmed to perform a cyclic etching process including a first operation and a second operation. In the first operation, the controller 815 opens the valve 807 to allow the oxygen-containing reactant to flow from the first source 803 into the reaction chamber 801, and after a set period of time, the controller 815 closes the valve 807 to the first source 803 (e.g., Figure 1 102 and Figure 6In some embodiments, when the semiconductor processing apparatus 800 includes a plasma unit (not shown), the controller 815 may be configured and programmed to pulse (turn on and then turn off) the plasma generator while causing the oxygen-containing reactant to flow from the first source 803 into the reaction chamber 801. Next, in a second operation, the controller 815 opens valve 808 to cause the first etchant to flow from the second source 804 into the reaction chamber 801, and after a set period of time, the controller 815 closes the valve to the second source 804 (e.g., Figure 1 104 and Figure 6 606 in 811). The controller 815 may be programmed to repeat the first operation and the second operation (n times) to remove the Mo outer layer of the target thickness from the substrate 811. The controller 815 may optionally be configured and programmed to perform other additional operations before, after and / or during the cyclic etching process.

[0092] In other embodiments, the controller 815 is configured and programmed to perform a cyclic etching process including a first operation, a second operation, and a third operation, etc. In the first operation, the controller 815 opens the valve 807 to allow the oxygen-containing reactant to flow from the first source 803 into the reaction chamber 801, and after a set period of time, the controller 815 closes the valve 807 to the first source 803 (e.g., Figure 2 202 and Figure 7 In some embodiments, when the semiconductor processing apparatus 800 includes a plasma unit (not shown), the controller 815 may be configured and programmed to pulse (turn on and then turn off) the plasma generator while causing the oxygen-containing reactant to flow from the first source 803 into the reaction chamber 801. Next, in a second operation, the controller 815 opens valve 808 to cause the first etchant to flow from the second source 804 into the reaction chamber 801, and after a set period of time, the controller 815 closes the valve to the second source 804 (e.g., Figure 2 204 and Figure 7 Then, in a third operation, the controller 815 opens the valve 809 to allow the second etchant to flow from the third source 805 into the reaction chamber 801, and after a set period of time, the controller 815 closes the valve 809 to the third source 805 (e.g. Figure 2 206 and Figure 7 808 in 708). The controller 815 can be programmed to repeat the first operation, the second operation, and the third operation (n times) to remove the Mo outer layer of the target thickness from the substrate 811. The controller 815 can optionally be configured and programmed to perform other additional operations before, after, and / or during the cyclic etching process.

[0093] The controller 815 may be further configured and programmed to perform other operations. For example, the controller 815 may be operably connected to a purge gas source (not shown), and configured and programmed to open a valve to the purge gas source to allow the purge gas to flow into the reaction chamber 801, and after a set time period, close the valve to the purge gas source. In another example, the controller 815 may be operably connected to one or more heaters (not shown) and one or more thermocouples (not shown), and configured and programmed to control the temperature of at least one heating element to maintain the temperature of the substrate 811 at a set temperature. In yet another example, in certain embodiments, the controller 815 may be further configured and programmed to perform a continuous etching operation before starting the first operation. In some embodiments, the controller 815 may be programmed to open the valve 810 to the fourth source 806 before the first operation to allow continuous etchant to flow into the reaction chamber 801, and after a set time period, the controller 815 closes the valve to the fourth source 806 (e.g. Figure 6 602 and Figure 7 702). Alternatively, in other embodiments, the first etchant and the continuous etchant are the same chemical compound, and the controller 815 can be programmed to open the second valve 808 leading to the second source 804 before the first operation to allow the first etchant to flow into the reaction chamber 801, and then close the second valve 808 leading to the second etchant. After the continuous etching operation, the controller 815 can be programmed to repeat the first operation and the second operation (n times) or repeat the first operation, the second operation, and the third operation (n times) to remove the target thickness of the Mo outer layer from the substrate 811.

[0094] In some embodiments, a system for etching a molybdenum surface comprises: a reaction space for accommodating a substrate, the substrate comprising a Mo outer layer having an initial thickness; a first source for providing an oxygen-containing reactant in gas communication with the reaction space via a first valve; a second source for providing a first etchant in gas communication with the reaction space via a second valve; and a controller operably connected to the first valve and the second valve. The controller is configured and programmed to perform a cyclic etching process by sequentially controlling: opening a first valve to the first source to supply an oxygen-containing reactant into the reaction space, wherein the oxygen-containing reactant converts at least a portion of the Mo outer layer into molybdenum oxide (MoO x ); closing a first valve leading to a first source to stop supplying an oxygen-containing reactant to the reaction space; opening a second valve leading to a second source to supply a first etchant to the reaction space, wherein the first etchant converts MoO xto a volatile Mo-containing compound; and closing the second valve to the second source to stop supplying the first etchant to the reaction space. In some embodiments, the controller is further programmed to sequentially repeat opening the first valve to the first source, closing the first valve to the first source, opening the second valve to the second source, and closing the second valve to the second source to reduce the initial thickness of the Mo outer layer to the final thickness or remove the Mo outer layer from the substrate. In some embodiments, the system also includes a third source for providing a second etchant that is gas-connected to the reaction space via a third valve, and the controller is also operably connected to the third valve and is configured and programmed to control: opening the third valve to the third source to supply the second etchant to the reaction space, wherein the second etchant removes the non-Mo oxide layer from the surface of the substrate; and closing the third valve to the third source to stop supplying the second etchant to the reaction space. The controller can also be programmed to open the third valve to the third source and close the third valve to the third source after each closing of the second valve to the second source.

[0095] In some embodiments, the system is further configured to provide a continuous etchant to the reaction space before performing the cyclic etching process. In some embodiments, the system is further configured to provide a continuous etchant to the reaction space before performing the cyclic etching process. In some of these embodiments, the continuous etchant and the first etchant are the same compound, and before opening the first valve to the first source, the controller is also programmed to open the second valve to the second source, and then close the second valve to the second source. In some other of these embodiments, the semiconductor device also includes a fourth source for providing a continuous etchant that is connected to the reaction space gas via a fourth valve, and the controller is also operably connected to the fourth valve, and is configured and programmed to control the opening of the fourth valve to the fourth source to supply the continuous etchant to the reaction space, wherein the continuous etchant reduces the initial thickness of the Mo outer layer to an intermediate thickness; and close the fourth valve to the fourth source to stop supplying the continuous etchant to the reaction space. Before opening the first valve to the first source, the controller is further programmed to open the fourth valve to the fourth source, and then close the fourth valve to the fourth source.

[0096] The methods and systems disclosed herein can be used in various applications in semiconductor device manufacturing. For example, the methods and systems disclosed herein can be used to form local interconnects on the surface of a substrate. The interconnects can be formed by forming at least one groove or recessed feature on the surface of the substrate and then filling the at least one groove or recessed feature with a suitable metal (e.g., molybdenum). Before filling the groove or recessed feature with metal, other lining or barrier layers can optionally be deposited in the groove or recessed feature. The metal deposition within the groove or recessed feature produces a metal outer layer or covering layer (e.g., a Mo outer layer) on at least a portion of the side surface of the substrate. Removal of the metal outer layer is necessary for further substrate processing. Fig. 9A , Fig. 9B and Fig. 9C An exemplary structure at different stages of fabrication is illustrated in FIG. Fig. 9A A substrate 904 is shown including recessed features 903 , which are optionally lined with a liner or barrier material 905 . Fig. 9B The substrate 904 is shown after the recessed features have been filled with molybdenum 906. An outer layer of Mo 907 exists on the substrate surface over the now filled recessed features. Fig. 9C The substrate 904 is shown after the outer layer of Mo is removed. The substrate 904 includes a filled recessed feature 906, wherein the filled recessed feature is optionally lined with a liner or barrier material 905 and filled with molybdenum 906. As will be appreciated by those skilled in the art, the methods and systems disclosed herein can be used to Fig. 9B The structure shown in FIG. 1 is stripped of the Mo outer layer 907 to obtain Fig. 9C The structure shown.

[0097] In another example, the methods and systems disclosed herein can be used for word lines, or more generally, memory cell separation during the manufacture of a 3D memory stack structure. Typically, memory line features in a 3D memory stack can be formed by depositing multiple alternating material layers and sacrificial layers on a substrate. At least one trench is then formed through various material layers and sacrificial layers, forming at least two adjacent stacks and exposing the vertical surfaces of the material layers and sacrificial layers that constitute the trench sidewalls. Next, at least a portion of each sacrificial layer is selectively removed, leaving gaps between some or all of the material layers. The gaps are then filled with a metal material (e.g., molybdenum) using a suitable deposition method (e.g., chemical vapor deposition or atomic layer deposition). The deposition process also results in the formation of a metal outer layer or capping layer (e.g., Mo outer layer) on the sidewalls and bottom of the trench and in some cases on the top of the stack, thereby electrically connecting various metallic layers. The removal of the metal outer layer separates the memory cell lines from each other.

[0098] exist Fig. 10A , Fig. 10B and Fig. 10C An exemplary intermediate 3D NAND stack structure at various stages of fabrication is illustrated in FIG. Fig. 10A Two intermediate 3D NAND stacks 1000 are shown separated by trenches 1009, each stack comprising multiple stacked oxide layers 1004 supported by memory strings 1005 on a substrate 1003. Each stack includes a top 1006 and sidewalls 1007 with multiple openings therein due to gaps 1008 between oxide layers 1004. A given stack may have from 2 to 256 gaps or more, with more advanced devices having greater numbers. Fig. 10B The two intermediate 3D NAND stacks 1001 are shown after the gaps have been filled with molybdenum 1010. During Mo deposition, an outer layer of Mo 1011 is formed on the sidewalls 1007 and bottom of the trenches 1011, electrically connecting the various molybdenum lines 1010 within the stack. Fig. 10C Two intermediate 3D NAND stacks 1002 are shown after the Mo outer layer has been removed, thereby separating the plurality of molybdenum wires 1010 from each other. As will be appreciated by those skilled in the art, the methods and systems disclosed herein can be used to Fig. 10B The intermediate 3D NAND stack structure 1001 shown in the figure removes the Mo outer layer 1011, thereby separating the molybdenum lines 1010 from each other. More specifically, storage cell separation or line separation can be achieved by providing a substrate including an intermediate 3D NAND stack structure including a Mo outer layer in a reaction space and removing the Mo outer layer using the methods and systems disclosed herein. In some embodiments, the methods and systems disclosed herein are used to remove molybdenum from the sidewalls of the intermediate 3D NAND stack structure. In some embodiments, the molybdenum removal occurs under thermal conditions (i.e., in a plasma-free environment). In some embodiments, the substrate is maintained at a temperature of 450°C or less, or a temperature of 425°C or less, or even a temperature of 400°C or less. Such conditions can advantageously allow molybdenum to be etched from the sidewalls of high aspect ratio recesses or trenches between two or more adjacent stacks.

[0099] exist Fig.11A , Fig. 11B and Fig. 11C An exemplary intermediate 3D DRAM stack structure at different stages of fabrication is illustrated in FIG. Fig.11A Two intermediate 3D DRAM stacks 1100 separated by trenches 1110 are shown, each stack including a plurality of alternating channel layers 1106 and insulating layers 1107 on a substrate 1104. Each stack can be divided into an inner stack region 1111 and an outer stack region 1112. The outer stack region 1112 also includes a plurality of sacrificial layers 1105 surrounding the outer portion of the channel layer 1106, each of which will be removed in subsequent manufacturing steps to form a plurality of capacitors. The inner stack region 1111 also includes a plurality of gate oxide material layers 1109 surrounding the inner portion of the channel layer 1106 and a plurality of gaps 1108 between the inner portion of the channel layer 1106 and the insulating layer 1107. Fig. 11B Two intermediate 3D DRAM stacks 1101 are shown after the various gaps have been filled with Mo 1113. During Mo deposition, an outer layer 1114 of Mo forms on the sidewalls 1115 and bottom of the trenches 1116, electrically connecting the various Mo lines 1113 within the stack. Fig. 11C Two intermediate 3D DRAM stacks 1102 are shown after the Mo outer layer has been removed, thereby separating the plurality of molybdenum lines 1113 from each other. As will be appreciated by those skilled in the art, the methods and systems disclosed herein can be used to Fig. 11B The intermediate 3D DRAM structure 1101 shown in the figure removes the Mo outer layer 1114, thereby separating the molybdenum lines 1113 from each other. More specifically, memory cell separation or line separation can be achieved by providing a substrate including an intermediate 3D DRAM stacking structure in a reaction space and removing the Mo outer layer using the methods and systems disclosed herein, the intermediate 3D DRAM stacking structure including the Mo outer layer. In some embodiments, the methods and systems disclosed herein are used to remove molybdenum from the sidewalls of the intermediate 3D DRAM stacking structure. In some embodiments, the removal of molybdenum occurs under thermal conditions (i.e., in a plasma-free environment). In some embodiments, the substrate is maintained at a temperature of 450°C or less, or a temperature of 425°C or less, or even a temperature of 400°C or less. Such conditions can advantageously allow molybdenum to be etched from the sidewalls of high aspect ratio recesses or trenches between two or more adjacent stacks.

[0100] Although certain embodiments and examples are disclosed herein, it will be understood by those skilled in the art that the disclosed methods and systems go beyond the specifically disclosed embodiments and include all novel and non-obvious combinations and sub-combinations of various methods, systems and configurations, as well as any and all equivalents thereof. It should be understood that the methods and / or systems and / or structures described herein are exemplary in nature, and these specific embodiments or examples should not be considered restrictive, as many variations are possible. The specific methods and systems described herein may represent one or more of any number of processing strategies. Therefore, the various steps shown may be performed in the order shown, in other orders, or omitted in some cases. In addition, for the purpose of simplifying the present disclosure, various features of the present disclosure are combined together in one or more aspects, embodiments and configurations. The features of the various aspects, embodiments and configurations of the present disclosure may be combined in alternative aspects, embodiments and configurations other than those discussed above. The methods, systems and structures of the present disclosure should not be interpreted as reflecting the intention that the claimed disclosure requires more features than those explicitly stated in each claim. On the contrary, as reflected in the following claims, the inventive aspects are less than all the features of the aspects, embodiments and configurations of the single aforementioned disclosure. Thus, the following claims are hereby incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment of the disclosure, and the features recited in the various dependent claims may be combined with one another in various combinations as appropriate to form further embodiments of the disclosure.

Claims

1. A method for etching molybdenum (Mo) from a substrate surface, the method comprising: providing a substrate including a Mo outer layer having an initial thickness in a reaction space; and Perform a cyclic etching process including: The substrate is exposed to an oxygen-containing reactant to convert at least a portion of the Mo outer layer into molybdenum oxide (MoO x ); Purge the reaction space; The substrate is exposed to a first etchant to remove MoO x Converting to a volatile Mo-containing compound, wherein the first etchant comprises one or more of a S—X bond, a P—X bond, and a Si—X bond, wherein X is Cl or Br; and Purge the reaction space.

2. The method according to claim 1, further comprising: The cyclic etching process is repeated to reduce the initial thickness of the Mo outer layer to a final thickness or to remove the Mo outer layer from the substrate.

3. The method according to claim 1, wherein: The first etchant is selected from thionyl chloride (SOCl2), sulfonyl chloride (SO2Cl2), sulfur dichloride (S2Cl2), thionyl bromide (SOBr2), sulfonyl bromide (SO2Br2), sulfur dibromide (S2Br2), phosphorus pentachloride (PCl5), phosphorus trichloride (PCl3), phosphorus oxychloride (POCl3), phosphorus pentabromide (PBr5), phosphorus tribromide (PBr3), phosphorus oxybromide (POBr3), silicon tetrachloride (SiCl4), trichlorosilane (SiHCl3), dichlorosilane (SiH2Cl2), chlorosilane (SiH3Cl), hexachlorodisilane (Si2Cl6), silicon tetrabromide (SiBr4), tribromosilane (SiHBr3), dibromosilane (SiH2Br2), bromosilane (SiH3Br), hexabromodisilane (Si2Br6) and combinations thereof.

4. The method according to claim 3, wherein: The first etchant is selected from SOCl2, PCl3, PCl5 and a combination thereof.

5. The method according to claim 1, wherein: The cyclic etching process further includes exposing the substrate to a second etchant to remove the non-Mo oxide layer from the substrate.

6. The method according to claim 5, wherein: The first etchant includes SiCl 4 , and the second etchant includes HF.

7. The method according to claim 1, wherein: The oxygen-containing reactant is selected from oxygen (O2), ozone (O3), water (H2O), hydrogen peroxide (H2O2), organic peroxides, alcohols, nitrogen dioxide (NO2), nitrous oxide (N2O), nitric oxide (NO), nitrogen pentoxide (N2O5), pyridine oxide (C5H5NO), amine oxide and combinations thereof.

8. The method according to claim 1, wherein: The oxygen-containing reactant includes one or more of O2, O3 and N2O.

9. The method according to claim 1, wherein: The cyclic etching process is performed under thermal conditions in a plasma-free environment.

10. The method of claim 1, further comprising heating the substrate to a temperature below about 450°C.

11. The method according to claim 1, wherein: X=Cl, and the volatile Mo-containing compound is molybdenum oxychloride.

12. The method of claim 1, further comprising performing a continuous etching step prior to the cyclic etching process, wherein the continuous etching step comprises exposing the substrate to continuous etchants.

13. The method according to claim 12, wherein: The continuous etchant is selected from molybdenum pentachloride (MoCl5), thionyl chloride (SOCl2), sulfonyl chloride (SO2Cl2), sulfur dichloride (S2Cl2), thionyl bromide (SOBr2), sulfonyl bromide (SO2Br2), sulfur dibromide (S2Br2), phosphorus pentachloride (PCl5), phosphorus trichloride (PCl3), phosphorus oxychloride (POCl3), phosphorus pentabromide (PBr5), phosphorus tribromide (PBr3), phosphorus oxybromide (POBr3), silicon tetrachloride (SiCl4), trichlorosilane (SiHCl3), dichlorosilane (SiH2Cl2), chlorosilane (SiH3Cl), hexachlorodisilane (Si2Cl6), silicon tetrabromide (SiBr4), tribromosilane (SiHBr3), dibromosilane (SiH2Br2), bromosilane (SiH3Br), hexabromodisilane (Si2Br6) and combinations thereof.

14. The method according to claim 12, wherein: The first etchant and the sequential etchant are the same chemical compound, wherein the substrate is maintained at a first temperature during the sequential etching step and maintained at a second temperature during the cyclic etching process, wherein the first temperature is greater than the second temperature.

15. The method according to claim 1, wherein: The substrate includes at least one intermediate 3D NAND stack structure or at least one intermediate 3D DRAM stack structure, wherein the Mo outer layer is located on at least one sidewall of the at least one intermediate 3D NAND stack structure or at least one intermediate 3D DRAM stack structure.

16. A method for etching a molybdenum-containing film, the method comprising: A substrate including a molybdenum-containing film is provided in a reaction space, wherein the molybdenum-containing film includes an outer layer located on a bulk region, wherein the outer layer includes molybdenum oxide (MoO x ), and the bulk region comprises metallic molybdenum; and The substrate is exposed to an etchant selected from the group consisting of thionyl chloride (SOCl2), sulfonyl chloride (SO2Cl2), sulfur dichloride (S2Cl2), thionyl bromide (SOBr2), sulfonyl bromide (SO2Br2), sulfur dibromide (S2Br2), phosphorus pentachloride (PCl5), phosphorus trichloride (PCl3), phosphorus oxychloride (POCl3), phosphorus pentabromide (PBr5), phosphorus tribromide (PBr3), phosphorus oxybromide (POBr3), silicon tetrachloride (SiCl4), trichlorosilane (SiHCl3), dichlorosilane (SiH2Cl2), chlorosilane (SiH3Cl), hexachlorodisilane (Si2Cl6), silicon tetrabromide (SiBr4), tribromosilane (SiHBr3), dibromosilane (SiH2Br2), bromosilane (SiH3Br), hexabromodisilane (Si2Br6) and combinations thereof to convert at least a portion of the outer layer of the molybdenum-containing film into a volatile Mo-containing compound, thereby reducing the thickness of the molybdenum-containing film.

17. The method according to claim 16, wherein: The etchant is selected from SOCl2, PCl3, PCl5, SiCl4 and combinations thereof.

18. A semiconductor processing device comprising: A reaction space for accommodating a substrate, the substrate comprising a Mo outer layer having an initial thickness; a first source for providing an oxygen-containing reactant in gaseous communication with the reaction space via a first valve; a second source for providing a first etchant in gas communication with the reaction space via a second valve, wherein the first etchant comprises one or more of an S—X bond, a P—X bond, and a Si—X bond, wherein X is Cl or Br; and A controller is operably connected to the first valve and the second valve, the controller being configured and programmed to perform a cyclic etching process by sequentially controlling: The first valve to the first source is opened to supply an oxygen-containing reactant into the reaction space, wherein the oxygen-containing reactant converts at least a portion of the Mo outer layer into molybdenum oxide (MoO x ); closing a first valve to a first source to stop supplying the oxygen-containing reactant to the reaction space; The second valve leading to the second source is opened to supply the first etchant into the reaction space, wherein the first etchant converts MoO x Converted into volatile Mo-containing compounds; as well as and closing the second valve to the second source to stop supplying the first etchant into the reaction space, wherein the controller is further programmed to sequentially repeat opening the first valve to the first source, closing the first valve to the first source, opening the second valve to the second source, and closing the second valve to the second source to reduce an initial thickness of the Mo outer layer to a final thickness or remove the Mo outer layer from the substrate.

19. The semiconductor device according to claim 18, wherein: The first etchant is selected from thionyl chloride (SOCl2), sulfonyl chloride (SO2Cl2), sulfur dichloride (S2Cl2), thionyl bromide (SOBr2), sulfonyl bromide (SO2Br2), sulfur dibromide (S2Br2), phosphorus pentachloride (PCl5), phosphorus trichloride (PCl3), phosphorus oxychloride (POCl3), phosphorus pentabromide (PBr5), phosphorus tribromide (PBr3), phosphorus oxybromide (POBr3), silicon tetrachloride (SiCl4), trichlorosilane (SiHCl3), dichlorosilane (SiH2Cl2), chlorosilane (SiH3Cl), hexachlorodisilane (Si2Cl6), silicon tetrabromide (SiBr4), tribromosilane (SiHBr3), dibromosilane (SiH2Br2), bromosilane (SiH3Br), hexabromodisilane (Si2Br6) and combinations thereof.

20. The semiconductor device according to claim 19, wherein The first etchant is selected from SOCl2, PCl3, PCl5, SiCl4 and a combination thereof.

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