Hydrogen reduction in amorphous carbon films.

Abstract

This specification provides examples of methods and associated apparatus for depositing an ashable hardmask (AHM) on a substrate using process gases including hydrocarbons and halide-containing species and pulsed low frequency (LF) power. The halide-containing species can reduce the hydrogen content of the AHM, and the pulsed LF power plasma can improve the mechanical properties of the AHM. This specification also provides examples of annealing hardmasks and processes for annealing hardmasks.

Description

[Background technology]

[0001] Amorphous carbon films may be used as hardmasks and etch stop layers in semiconductor processing, including the fabrication of memory and logic devices. These films are also known as ashable hardmasks (AHMs) because they can be removed by ashing techniques. The larger the aspect ratio in lithography, the higher the etch selectivity of the AHMs required. Current methods of forming highly selective AHMs using plasma enhanced chemical vapor deposition (PECVD) processes result in AHMs with high stress, limiting their usefulness as hardmasks. It is therefore desirable to fabricate AHMs with low stress while still having high etch selectivity.

[0002] The background and context descriptions contained herein are intended only to provide a general context for the present disclosure. Most of this disclosure presents the inventors' inventions, and merely because such inventions are described in the Background section or presented elsewhere in this specification does not mean that they are admitted as prior art. Summary of the Invention

[0003] Disclosed herein is a method and system for forming an ashable hardmask (AHM) film. The method includes receiving a substrate in a process chamber, exposing the substrate in the process chamber to a process gas including one or more hydrocarbon precursors and one or more halide-containing species, and depositing an AHM film on the substrate by a plasma-enhanced chemical vapor deposition (PECVD) process using the process gas. The PECVD process includes igniting a plasma generated by a dual radio frequency (RF) plasma source including a high frequency (HF) element and a low frequency (LF) element. The power of the HF element is constant during deposition, and the power of the LF element is pulsed at at least 1250 W per 300 mm wafer and with a duty cycle between 10% and 75%.

[0004] In some examples, the one or more halide-containing species include a fluorine-containing species. In some examples, the one or more halide-containing species include SF6, CF4, or both. In some examples, the one or more hydrocarbon precursors include acetylene, propylene, methane, or any combination thereof. In some examples, the flow rate of the one or more halide-containing species is between 1% and 20% of the flow rate of the one or more hydrocarbon precursors. In some examples, the flow rate of the one or more halide-containing species is between 5% and 15% of the flow rate of the one or more hydrocarbon precursors. In some examples, the flow rate of the one or more hydrocarbon precursors is between 100 sccm and 200 sccm. In some examples, the power of the HF element is at least 350 W per 300 mm wafer. In some examples, the processing chamber is at a temperature between 150° C. and 550° C. during the PECVD process. In some examples, the processing chamber is at a pressure between 0.5 torr and 5 torr during the PECVD process. In some examples, exposing the substrate to one or more halide-containing species occurs after ignition of the plasma, and the one or more halide-containing species are flowed into the plasma. In some examples, the AHM film is deposited on a layer of a substrate comprising poly-Si, SiO2, Si3N4, or any combination thereof. In some examples, the AHM film has a modulus of at least 120 GPa. In some examples, the AHM film has a hardness of at least 14 GPa. In some examples, the AHM film has a hardness between 14 GPa and 16 GPa. In some examples, the AHM film has a hydrogen content of less than 20% atomic. In some examples, the AHM film has a hydrogen content of less than 15% atomic.

[0005] Examples relating to annealing carbon hardmasks are also disclosed. One example provides a method of processing a substrate. The substrate includes a carbon hardmask. The method includes placing the substrate in an annealing tool. The carbon hardmask has a first stress and a first hydrogen content. The method further includes annealing the substrate to form an annealing carbon hardmask having a second stress and a second hydrogen content. The second stress is lower than the first stress. The second hydrogen content is lower than the first hydrogen content. In some such examples, the substrate includes a three-dimensional integrated circuit mold stack on which the carbon hardmask is disposed. In some such examples, instead or in addition, the second, lower hydrogen content of the annealing carbon hardmask is 10 atomic percent or less. In some such examples, instead or in addition, the second, lower stress of the annealing carbon hardmask is 1 MPa (megapascal) or more and 100 MPa or less. In some such examples, annealing the substrate such that the annealed carbon hardmask has a second, lower stress may alternatively or additionally include annealing the substrate such that the annealed carbon hardmask exhibits an elastic modulus of 60 GPa or more and 250 GPa or less. In some such examples, annealing the substrate such that the annealed carbon hardmask has a second, lower stress may alternatively or additionally include annealing the substrate such that the annealed carbon hardmask exhibits an average grain size change of 15% or less compared to the carbon hardmask. In some such examples, annealing the substrate such that the annealed carbon hardmask has a second, lower stress may alternatively or additionally include annealing the substrate such that the annealed carbon hardmask exhibits an average grain size change of 10% or less compared to the carbon hardmask. 3 annealing the substrate such that the carbon hard mask exhibits a change in carbon content. In some such examples, alternatively or additionally, annealing the substrate such that the annealed carbon hard mask has a second, lower stress includes annealing the substrate at a temperature within a temperature range of 500 to 1000 degrees Celsius.

[0006] Another example provides a method of treating a substrate. The method includes depositing a carbon hard mask, annealing the carbon hard mask to form an annealed carbon hard mask, patterning the annealed carbon hard mask, and etching the substrate. In some such examples, alternatively or additionally, depositing the carbon hard mask includes depositing the carbon hard mask such that the carbon hard mask exhibits an elastic modulus of 60 GPa or more and 250 GPa or less. In some such examples, alternatively or additionally, depositing the carbon hard mask includes depositing the carbon hard mask using thermal chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), or remote plasma enhanced chemical vapor deposition (RPECVD). In some such examples, alternatively or additionally, annealing the carbon hard mask includes annealing the carbon hard mask under an inert atmosphere. In some such examples, alternatively or additionally, annealing the carbon hard mask includes annealing the carbon hard mask at a temperature higher than the deposition temperature and in a temperature range of 500 to 1000°C. In some such examples, annealing the carbon hardmask alternatively or additionally includes annealing the carbon hardmask such that the annealed carbon hardmask exhibits a hydrogen content of 10 atomic percent or less. In some such examples, annealing the carbon hardmask alternatively or additionally includes annealing the carbon hardmask such that the annealed carbon hardmask exhibits a stress of 1 MPa or more and 100 MPa or less. In some such examples, annealing the carbon hardmask alternatively or additionally includes annealing the carbon hardmask such that the annealed carbon hardmask exhibits an elastic modulus of 60 GPa or more and 250 GPa or less. In some such examples, annealing the carbon hardmask alternatively or additionally includes annealing the carbon hardmask such that the annealed carbon hardmask exhibits a change in average grain size of 15% or less compared to the carbon hardmask.In some such examples, annealing the carbon hard mask may alternatively or additionally reduce the sp. of the annealed carbon hard mask by 10% or less compared to the carbon hard mask. 3 Annealing the carbon hard mask to exhibit a change in carbon content.

[0007] Another example provides a structure in a 3D memory fabrication process. The structure includes a substrate and an annealed carbon hardmask disposed on the substrate. The annealed carbon hardmask film has an elastic modulus of 60 GPa or more and 250 GPa or less and a stress of 1 MPa or more and 100 MPa or less. In some such examples, alternatively or additionally, the annealed carbon hardmask has a hydrogen content of 10 atomic percent or less.

[0008] These and other features of the disclosed examples are described in detail below with reference to the associated drawings. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a process flow diagram illustrating relevant acts of a method of using an ashable hardmask (AHM) in an etching operation, according to various examples.

[0010] [Diagram 2] FIG. 2 shows a schematic diagram of etching a stack of alternating layers in one example.

[0011] [Diagram 3] FIG. 3 is a process flow diagram illustrating relevant operations of a method for forming an ashable hardmask, according to various examples herein.

[0012] [Figure 4] FIG. 4 is a table of film properties of AHM deposited using various process gases.

[0013] [Diagram 5]FIG. 5 shows the FTIR spectra of the ashable hard mask with different ratios of SF6.

[0014] [Figure 6] FIG. 6 shows the FTIR spectra of the ashable hard mask with different ratios of CF4.

[0015] [Figure 7] FIG. 7 shows a schematic diagram of a plasma-enhanced chemical vapor deposition (PECVD) chamber suitable for practicing the various examples.

[0016] [Figure 8A] FIG. 8A illustrates a schematic of an exemplary etching process utilizing a carbon hard mask that has poor etch selectivity to the etching process. [Figure 8B] FIG. 8B illustrates a schematic of an exemplary etching process utilizing a carbon hard mask that has poor etch selectivity for the etching process. [Figure 8C] FIG. 8C illustrates a schematic of an exemplary etching process utilizing a carbon hard mask that has poor etch selectivity for the etching process. [Figure 8D] FIG. 8D illustrates a schematic of an exemplary etching process utilizing a carbon hard mask that has poor etch selectivity for the etching process. [Figure 8E] FIG. 8E illustrates a schematic of an exemplary etching process utilizing a carbon hard mask that has poor etch selectivity for the etching process.

[0017] [Figure 9A] FIG. 9A illustrates a schematic of an exemplary etching process using an annealed carbon hard mask that provides sufficient etch selectivity for the etching process of FIGS. 1A-1E. [Figure 9B] FIG. 9B illustrates a schematic of an exemplary etching process using an annealed carbon hard mask that has sufficient etch selectivity for the etching process of FIGS. 1A-1E. [Figure 9C] FIG. 9C illustrates a schematic of an exemplary etching process using an annealed carbon hard mask that has sufficient etch selectivity for the etching process of FIGS. 1A-1E. [Figure 9D] FIG. 9D illustrates a schematic of an exemplary etching process using an annealed carbon hard mask that has sufficient etch selectivity for the etching process of FIGS. 1A-1E. [Figure 9E] FIG. 9E illustrates a schematic of an exemplary etching process using an annealed carbon hard mask that provides sufficient etch selectivity for the etching process of FIGS. 1A-1E. [Figure 9F] FIG. 9F illustrates a schematic of an exemplary etching process using an annealed carbon hard mask that has sufficient etch selectivity for the etching process of FIGS. 1A-1E.

[0018] [Figure 10] FIG. 10 is a flow diagram illustrating an exemplary process for forming an annealed carbon hard mask.

[0019] [Figure 11] FIG. 11 is a flow diagram illustrating an exemplary process for depositing a carbon hardmask, annealing the carbon hardmask, and using the annealed carbon hardmask in an etching process.

[0020] [Figure 12] FIG. 12 shows a block diagram of an exemplary deposition tool.

[0021] [Figure 13] FIG. 13 shows a block diagram of an exemplary annealing tool.

[0022] [Figure 14] FIG. 14 illustrates another schematic diagram of another plasma enhanced chemical vapor deposition (PECVD) chamber suitable for practicing various examples.

[0023] [Figure 15] FIG. 15 shows a schematic diagram of a module cluster suitable for implementing various examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] The term "alkane" generally refers to an alkane having the general formula C n H 2n+2 represents a compound containing the formula: Examples of alkanes include methane, ethane, propane, and butane. Examples of alkanes that may be suitable for use as carbon-containing precursors as disclosed herein include alkanes where n=1-10.

[0025] The term "alkene" generally refers to a hydrocarbon compound that contains at least one carbon-carbon double bond. Alkenes that contain one carbon-carbon double bond have the general formula C n H 2n Examples of alkenes include ethylene, propylene, and butylenes. Alkenes may have two or more carbon-carbon double bonds, such as dienes, arenes, and cumulenes. Examples of alkenes that may be suitable for use as carbon-containing precursors include alkenes where n=2-10.

[0026] The term "alkylamine" generally refers to a nitrogen-containing hydrocarbon compound having one to three alkyl substituents and zero to two H substituents. Alkylamines may include primary amines, secondary amines, tertiary amines, and cyclic amines. Examples of alkylamines suitable for use as carbon-containing precursors include methylamine, dimethylamine, trimethylamine, and piperidine.

[0027] The term "alkyne" generally refers to a hydrocarbon compound that contains at least one carbon-carbon triple bond. Alkynes that contain one carbon-carbon triple bond can be represented by the general formula C n H 2n-2The alkynes may have more than one carbon-carbon triple bond, such as diynes having two carbon-carbon triple bonds. Examples of alkynes suitable for use as carbon-containing precursors include alkynes where n=2-10.

[0028] The terms "anneal," "annealing," and variations thereof generally refer to the process of heating a carbon hardmask for a period of time after deposition of the carbon hardmask. Annealing can be used for purposes such as stress relief, removal of volatile species, structural improvement, and control of grain size and / or surface roughness.

[0029] The term "annealing tool" generally refers to a tool used for annealing a substrate. The annealing tool is configured to expose the substrate to elevated temperatures (e.g., 400° C. or higher) in a controlled gas environment. The annealing tool may also be referred to as a furnace.

[0030] The term "carbon-containing precursor" generally refers to a carbon-containing compound that can be introduced into a process chamber in the gas phase to form a carbon hard mask on a substrate in the process chamber. Carbon-containing precursors can include carbon-containing gases such as low molecular weight hydrocarbons. Examples of carbon-containing precursors include those having the general formula C, where n is an integer ranging from 1 to 10: n H 2n+2 Alkanes (e.g., methane, ethane, etc.) having the general formula C n H 2n Alkenes having the general formula C n H 2n-2 Examples of carbon-containing precursors include alkynes (acetylene, propyne, etc.) having the formula: which are in the gas phase under the process conditions. Other examples of carbon-containing precursors include nitrogen-containing compounds including aliphatic and aromatic cyclic hydrocarbons, alkylamines, and oxygen-containing compounds including alcohols, ketones, esters, aldehydes, and ethers, which are in the gas phase under the process conditions.

[0031] The terms "carbon hardmask" and "ashable hardmask" (AHM) generally refer to a layer of carbon used as a selective film in an etching process. A carbon hardmask may, in some instances, include amorphous carbon. Amorphous carbon is a type of carbon that is composed of sp 2 Carbon and sp 3 The carbon may comprise both.

[0032] The term "chemical vapor deposition" generally describes a process in which a film is formed on a substrate by a continuous flow of reactive gas-phase precursors. Plasma-enhanced CVD (PECVD) uses a plasma to form reactive species from gas-phase precursors to facilitate film formation. Thermal CVD (TCVD) uses heat to facilitate film formation. Remote plasma-enhanced CVD (RPECVD) uses a remote plasma to form reactive species from gas-phase precursors to facilitate film formation.

[0033] The term "dual radio frequency plasma source" generally refers to a set of elements configured to form a plasma using radio frequency energy at two different frequencies. A dual radio frequency plasma source can form a plasma having a high frequency element and a low frequency element. The terms "high frequency element" and "low frequency element" are relative to each other and can take any suitable values.

[0034] The term "duty cycle" generally refers to the percentage of time that power to an electronic component is on. The duty cycle is defined as DC=t on / (t on +t off ), where t on is the period during which the power is on, and t off is the period during which the power is off.

[0035] The terms "etch", "etching", and variations thereof generally refer to a process for removing material from a substrate surface. Etching processes can use chemical and / or physical material removal mechanisms. Dry etching processes are etching processes that utilize a gas phase etchant. Wet etching is an etching process that utilizes a liquid phase etchant.

[0036] The terms "etch selectivity," "selectivity," and variations thereof generally refer to the ratio of the etch rate of one material to the etch rate of another material.

[0037] The term "flow control hardware" generally refers to elements configured to fluidly connect one or more chemical sources to a processing chamber. The flow control hardware may include, for example, one or more mass flow controllers and / or one or more valves. Examples of chemical sources include a film precursor source, an inert gas source, and a reactive gas source.

[0038] The term "grain" generally refers to a short-range arrangement of atoms within a film or layer. The grains may vary in size, shape, orientation, and crystallinity.

[0039] The term "grain size" generally refers to the diameter of the individual grains of the membrane material. The grain size of the membrane material can be determined using a variety of measurement techniques. An exemplary measurement technique for measuring grain size is Raman spectroscopy.

[0040] The term "halide-containing species" generally refers to molecules that have a halogen anion. Examples of halide-containing species include fluorine-, chlorine-, and bromine-containing species.

[0041] The term "hardness" generally describes a material's resistance to localized plastic deformation.

[0042] The term "high aspect ratio" generally refers to features having a ratio of feature height to feature width in the range of 1:1 to 100:1 (height:width).

[0043] The term "mold stack" generally refers to a structure including multiple alternating layers of material formed in a three-dimensional (3D) integrated circuit manufacturing process. In some examples, the mold stack may include alternating oxide and nitride layers. In other examples, the mold stack may include alternating oxide and polycrystalline silicon (polysilicon) layers. In further examples, the mold stack may include any other suitable alternating layers of material.

[0044] The terms "modulus" and "elastic modulus" generally refer to the physical unit of resistance to elastic deformation when an applied stress is applied to a material. The elastic modulus is a measure of the mechanical strength of a material.

[0045] The term "patterning" generally refers to the process of forming structures on a substrate by selectively masking or exposing selected areas of the substrate for topology generation in subsequent deposition or etching processes.

[0046] The term "plasma" generally refers to a gas that contains cations and free electrons.

[0047] The term "process gas" generally refers to a gas or mixture of gases that is introduced into a processing chamber when performing a process on a substrate.

[0048] The term "processing chamber" generally refers to an enclosure in which chemical and / or physical processes are performed on a substrate. The pressure, temperature, and atmospheric composition within the processing chamber can be controlled to carry out the chemical and / or physical processes.

[0049] The term "processing tool" generally refers to equipment that includes a processing chamber and other hardware configured to enable a process to be performed in the processing chamber.

[0050] The term "purging" generally refers to the process of removing unwanted species from a processing chamber.

[0051] The term "reactive ion etching (RIE)" generally refers to a dry etching process that involves accelerating chemically reactive species (ions) towards a substrate in a low pressure environment.

[0052] The term "remote plasma" generally refers to a plasma used to generate reactive species at a location remote from the substrate being processed.

[0053] The term “sp 2 "Carbon" generally refers to a carbon atom bonded to three other atoms in a roughly planar trigonal arrangement.

[0054] The term “sp 3 "Carbon" generally refers to a carbon atom bonded to four other atoms in an approximately tetragonal arrangement.

[0055] The term "stress" generally refers to the force per unit area that produces strain in a film or layer. Stress can be calculated by measuring the change in radius of curvature of a substrate caused by deposition of a layer onto the substrate. If the change in radius of curvature is positive, the stress may be referred to as "tensile stress." If the change in radius of curvature is negative, the stress may be referred to as "compressive stress."

[0056] The term "substrate" generally refers to any object upon which a film can be deposited.

[0057] The term "three-dimensional integrated circuits" generally refers to structures in which integrated circuit elements are stacked vertically in addition to being arranged horizontally across a wafer. Examples of 3D integrated circuits include 3D memory devices. Examples of 3D memory devices include 3D NAND flash memory, 3D NOR, and 3D DRAM.

[0058] The term "3D DRAM" is an acronym for three-dimensional dynamic random-access memory.

[0059] The term "3D NAND" is an acronym for three-dimensional NOT AND memory and generally refers to a memory architecture based on NOT AND logic gates.

[0060] The term "3D NOR" is an acronym for three-dimensional NOT OR memory and generally refers to a memory architecture based on NOT-OR logic gates.

[0061] The term "atomic percent" generally refers to the number of atoms of an element relative to the total number of atoms in a composition.

[0062] Semiconductor device processing includes the formation of multilayer stacks that can be used to fabricate various three-dimensional devices, such as 3D NAND structures. Some stacks include multiple alternating layers of dielectric and conductive materials, each of which may be about 10 nm or thicker. One approach to forming such stacks includes the deposition of multiple alternating layers of oxide and nitride materials (ONON multilayer deposition), followed by selective removal of material and backfill deposition of metal into the space previously occupied by the nitride material. In another approach, a stack of multiple alternating layers of oxide and polysilicon (or "poly" as used elsewhere herein) is directly patterned. The polysilicon is maintained as the conductive layer. These methods may be used to fabricate 3D NAND structures.

[0063] The etching of the stack may be performed using a patterned amorphous carbon film. The amorphous carbon film may also be referred to as an ashable hard mask (AHM). The amorphous carbon layer may be suitable as a hard mask with high selectivity during the etching process of the stack. The high selectivity is determined in the context of a particular etching chemistry. For a particular etching chemistry, the underlying substrate, such as an ONON layer, is etched much faster than the hard mask, such as an amorphous carbon layer. In various applications described herein, the underlying substrate includes silicon oxide, silicon nitride, and / or polysilicon.

[0064] For 3D NAND applications, the ashable hardmask may be carbon-based and thicker than about 1.5 micrometers. Such thickness may be necessary for applications requiring etching of high aspect ratio features, such as those used in forming some memory devices (e.g., 3D NAND devices). In some cases, or in certain examples, applications using amorphous carbon hardmasks formed as described herein etch stacks of alternating layers of silicon oxide and silicon nitride, or alternating layers of polysilicon and silicon oxide. A significant contributor to the cost of 3D NAND is the time it takes to deposit AHMs. At a rate of about 0.25 micrometers / min and a target layer of 2 μm thickness, deposition may take 8 minutes or more. It is therefore desirable to increase the etch selectivity of the AHM to allow etching of underlying layers with thinner AHMs.

[0065] FIG. 1 illustrates a process flow diagram of operations performed according to a method of forming a 3D NAND structure. In operation 182, a substrate is provided. In various examples, the substrate is a semiconductor substrate. The substrate may be a silicon wafer (e.g., a 200 mm wafer, a 300 mm wafer, or a 450 mm wafer, etc.), including a wafer having one or more layers of material deposited thereon, such as a dielectric material, a conductive material, or a semiconductive material. In operation 184, a film stack of alternating dielectric and conductive layers is deposited on the substrate. In some examples, the dielectric layer is an oxide layer. In various examples, the deposited oxide layer is a silicon oxide layer. In various examples, the conductive layer is a nitride layer, such as a silicon nitride layer. In some examples, the conductive layer is a polysilicon layer. Each of the dielectric layer and the conductive layer is deposited to approximately the same thickness, such as between about 10 nm and about 100 nm, or about 350 Å, in some examples. The oxide layer may be deposited at a deposition temperature between about room temperature and about 600° C. It will be understood that "deposition temperature" (or "substrate temperature") as used herein refers to the temperature at which the pedestal holding the substrate is set during deposition.

[0066] The oxide layers and conductive layers to form the alternating oxide and nitride film stack may be deposited using any suitable technique, such as atomic layer deposition (ALD), plasma-enhanced atomic layer deposition (PEALD), chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), physical vapor deposition (PVD), or sputtering. In various examples, the oxide and nitride layers are deposited by PECVD.

[0067] The film stack may include between 48 and 512 alternating layers of dielectric and conductive layers, with each dielectric or conductive layer constituting one layer. In some examples, the film stack may include fewer than 48 or more than 512 alternating dielectric and conductive layers, depending on the application. A film stack including alternating oxide and nitride layers may be referred to as an ONON stack. While the film stack described above may include alternating oxide and nitride layers, it will be understood that the stack may include additional layers, and furthermore, other materials may be used for the alternating layers that are not oxide and nitride layers. For example, in some cases, silicon germanium layers may be used instead of nitride or silicon nitride layers. Other additional layers that may be on the stack include silicon-containing layers, germanium-containing layers, or both. Examples of silicon-containing layers include doped and undoped silicon carbide layers, doped and undoped polysilicon layers, amorphous silicon layers, doped and undoped silicon oxide layers, and doped and undoped silicon nitride layers. The dopant may include a nonmetallic dopant. For example, the doped silicon carbide layer is silicon carbide doped with oxygen. In another example, the doped silicon carbide layer is silicon carbide doped with nitrogen. Further discussion of layer deposition and etching for 3D NAND applications can be found in application PCT / US2019 / 050369, filed September 10, 2019.

[0068] In operation 186, an amorphous carbon film is formed on the substrate. The amorphous carbon film has various properties described herein that make it suitable as a mask for etching the underlying substrate. In certain applications, the film has a thickness of at least about 1 μm. In certain examples, the film has a thickness of at least about 1.5 μm. In certain examples, the film has a thickness of at least about 2 μm. In some examples, the film has a thickness between about 1 μm and about 2 μm. In operation 188, the amorphous carbon film is patterned to expose portions of the underlying substrate. Patterning may be accomplished, for example, by a lithographic process.

[0069] In operation 190, the film stack is etched. The etching chemistry used is selective to the amorphous carbon film compared to the underlying substrate, and therefore the amorphous carbon film etches slower than the layers of the film stack. Examples of etches include radical and / or ion-based etches. Examples of etch chemistries include halogen-based etch chemistries, such as fluorine-containing etch chemistries, bromine-containing etch chemistries, and chlorine-containing etch chemistries. For example, a capacitively coupled plasma generated from a fluorocarbon-containing process gas may be used to selectively etch the oxide layer. A specific example of a process gas is C4H8 / CH2F2 / O2 / Ar, optionally with oxygen (O2) and an inert gas. x F y In a particular example, the amorphous carbon layer is used as a hard mask in an etching process where the etching species are generated in a plasma.

[0070] Finally, in operation 192, the amorphous carbon film is removed, for example, by a technique called ashing, plasma ashing, or dry stripping. Ashing may be performed by oxygen-rich dry etching. Often, oxygen, for example in the form of O2, N2O, and NO, is introduced into the chamber under vacuum, and RF power creates oxygen radicals in the plasma that react with the AHM and oxidize it to water (H2O), carbon monoxide (CO), and carbon dioxide (CO2). Optionally, any remaining AHM residues may be removed by a wet or dry etching process after ashing. The result is a patterned substrate layer.

[0071] FIG. 2 provides schematic diagrams 100-150 of operations 182-192 of FIG. 1. In FIG. 100, a substrate 105 is provided. The substrate 105 may be a silicon wafer having one or more layers previously formed thereon. In FIG. 110, alternating layers of oxide films (101) and nitride films (102) are deposited on the substrate 105. Note that although in the structure shown in FIG. 2, the oxide is deposited first, followed by the nitride, oxide, nitride, etc., the nitride may be deposited first, followed by the oxide, nitride, oxide, etc.

[0072] In Fig. 120, an amorphous carbon film 103 is deposited over the stack of oxide and nitride films. Details of this process are discussed further herein. In Fig. 130, the amorphous carbon film 103 is patterned to expose portions of the underlying stack. The exposed portions of the amorphous carbon film 103 define areas where high aspect ratio features are etched. In Fig. 140, the underlying stack is etched using the amorphous carbon film 103 as a mask to form various features in the stack of alternating layers. In Fig. 150, the amorphous carbon film 103 is removed, resulting in a stack of alternating layers of oxide and nitride films with etched various features.

[0073] In some examples, features etched using the AHMs described herein may have an aspect ratio of about 10: 1 to about 1000: 1. In some examples, the opening size of the features may have a width of about 20 to 100 nm.

[0074] Certain processes for depositing amorphous carbon hardmasks employ a carbon precursor, which may be a hydrocarbon, such as propylene. In some cases, the hydrocarbon precursor has a relatively high carbon-to-hydrogen ratio, such as acetylene. In some instances, propylene is an advantageous carbon precursor because it has a low tendency to polymerize and clog holes in the showerhead or deposit on sensitive parts of the deposition chamber. Propylene may also be advantageous due to safety concerns at the high pressures and temperatures employed in the processes described herein. Other hydrocarbon species may be used, including methane, propylene, acetylene, or any combination thereof.

[0075] In addition to propylene or other suitable carbon-containing precursors, the process may employ an inert or chemically non-reactive gas, such as argon, helium, nitrogen, or any combination thereof.

[0076] Conventional processes can produce amorphous carbon layers with large amounts of hydrogen. The presence of hydrogen generally reduces the etch selectivity of the AHM. While deposition at higher temperatures can reduce the hydrogen content, it can adversely affect modulus and hardness and reduce etch selectivity.

[0077] Another method to reduce hydrogen content is co-flow of halide-containing species. Adding certain reactants to the process gas, such as halide-containing species, can reduce the presence of hydrogen in the deposited film. Generally, a hydrocarbon precursor is flowed into the plasma to form carbon ions, as well as hydrogen ions and / or hydrogen radicals, among other particles. The hydrogen radicals or hydrogen ions can interact with carbon atoms deposited on the surface of the hard mask, incorporating hydrogen into the deposited film and even removing deposited carbon from the film, resulting in an etching process that reduces the deposition rate.

[0078] Without being bound by theory, halide-containing species such as SF6 may form SF5 and HF by reacting with the hydrocarbon precursors and / or hydrogen radicals formed during the deposition process. The SF5 and HF may be vented from the processing chamber without etching the hardmask. The generation of HF reduces the presence of hydrogen radicals to suppress the competing etching process, thus increasing the overall deposition rate. Other halide-containing species that react with hydrogen radicals and / or hydrogen ions, such as CF4, may also be used.

[0079] Flowing a halide-containing species may reduce the hydrogen content of the AHM, but the halide-containing species may be deposited in the film as impurities and typically also reduce the mechanical properties of the film (e.g., lower modulus and hardness). The reduced modulus and hardness from halide-containing species (e.g., sulfur or fluorine) and the presence of impurities may reduce the etch selectivity of the film more than the reduced hydrogen content improves the etch selectivity. This net reduction in etch selectivity is undesirable.

[0080] The RF power may be controlled to improve the mechanical properties of the AHM. The AHM film may be deposited using a PECVD process. In the PECVD process, a plasma is ignited using low frequency (LF) and high frequency (HF) power. The pulsed output of the LF power may allow ions to bombard the surface when the LF power is on, increasing the density. Meanwhile, when the LF power is off, the ions may form an ordered structure with lower stress, decreasing the stress. Increasing the density while decreasing the stress may improve the mechanical properties of the film, especially the hardness and modulus. The LF power may be characterized by a duty cycle. As illustrated and known in the art, the duty cycle (DC) is expressed by the equation DC=t on / (t on +t off) and represents the percentage of time that the power is on or set to high power. Both the duty cycle and pulse frequency can be used to determine the time that the LF power is on. That is, a 100 Hz pulse frequency with a 25% duty cycle indicates that the LF power is on for 2.5 ms and off for 7.5 ms. The HF power may be maintained as a non-pulsed output (constant), while the LF power is pulsed.

[0081] 3 is a process flow diagram illustrating relevant operations of a method for forming AHMs by adjusting dual RF plasma power, according to various examples. In operation 302, a substrate is received in a processing chamber. The substrate may be provided to the chamber in this operation or may already be in the chamber from a previous operation. In operation 304, the substrate is exposed to a process gas including a hydrocarbon precursor and a halide-containing species. In addition to the hydrocarbon precursor, an inert gas carrier may be used. The inert gas may include helium (He), argon (Ar), nitrogen (N2), hydrogen (H2), or any combination thereof.

[0082] Next, in operation 306, a plasma is ignited using a dual RF plasma source that generates a plasma having pulsed low frequency (LF) and high frequency (HF) components to deposit an ashable hard mask on the substrate by a PECVD process. The pulsed LF component may occur by pulsing the LF power source. In some examples, pulsing the LF RF power includes using high power, fast pulses, and low duty cycles to produce high peak energy ion bombardment with low average ion density. In some examples, a halide-containing species may be flowed after the plasma is ignited. The halide-containing species may act as an etchant for the hard mask or other materials in the processing chamber. Thus, flowing the halide-containing species after plasma ignition may inhibit any etching process because the halide-containing species may instead react with ions and radicals formed from the hydrocarbon precursor flowed into the plasma.

[0083] Operation 306 results in an AHM film. This process produces films with better density-to-stress ratios and higher selectivity. The pulse frequency may be adjusted to maintain high average ion energy while varying the average ion density depending on the duty cycle of the LF power. In some examples, decreasing the duty cycle may produce a film with a low modulus and low stress. In other examples, increasing the duty cycle may produce a film with a high modulus and high stress. Increasing the duty cycle may also increase the deposition rate of the AHM film. Depending on other process conditions, both types of films may be desirable.

[0084] FIG. 4 is a table showing the effect on various film properties when SF6 and CF4 are included in the process gas, as well as when the film is deposited without any halide-containing species flowing. As shown in FIG. 4, increasing the flow rate of SF6 to 5% of the flow rate of C2H2 reduced the hydrogen content of the resulting AHM from about 21% to about 14.7%. A similar reduction in hydrogen content was also seen with the co-flow of CF4. Of note, the modulus and hardness of the resulting film are relatively similar to those of the baseline film where no halide-containing species are flowed. The co-flow of SF6 reduced the hydrogen content more than CF4, and also reduced the modulus and hardness more than CF4 (while the overall reduction in modulus and hardness is still limited). Conversely, the co-flow of CF4 did not reduce the hydrogen content as much as SF6, but the modulus and hardness values ​​were closer to the film deposited without the co-flow of halide-containing species.

[0085] Other process conditions for all deposited films shown in FIG. 4 were pedestal temperature of 250° C., pressure of 0.5 Torr, C2H2 flow rate of 125 sccm, 4500 W at 13.56 MHz, and 600 W at 400 kHz with a duty cycle of 62%.

[0086] High aspect ratio patterning uses AHMs with high etch selectivity. Etch selectivity can be determined by comparing the etch rate of the AHM layer to the underlying layer. Etch selectivity can be approximated by determining the hydrogen content, refractive index (RI), density, and Young's modulus or stiffness of the AHM layer, in some cases. Typically, AHMs with lower hydrogen content, higher RI, higher density, and higher modulus or stiffness can withstand higher etch rates in etch processes that include more ion bombardment. Thus, AHMs with lower hydrogen content, higher RI, higher density, and / or higher modulus have higher selectivity and lower etch rates and can be used more efficiently and effectively for high aspect ratio semiconductor processing. The desired etch selectivity of an AHM may depend on the etch process and the composition of the underlying layer, but the correlation between etch selectivity and the above-mentioned material properties may remain the same regardless of the etch process or composition of the underlying layer. The selectivity correlation as described herein applies to all types of underlying layers, including polysilicon layers, oxide layers, and nitride layers.

[0087] AHM films produced according to the disclosed methods are typically composed primarily of carbon and hydrogen, although other elements may be present in the film. In some examples, the carbon concentration is at least about 70 percent atomic. Examples of other elements that may be present in the AHM film include halogens, nitrogen, sulfur, boron, oxygen, tungsten, titanium, and aluminum. Typically, such other elements are present in amounts of about 10 percent atomic or less. In some examples, the hydrogen concentration is less than about 20% atomic, less than about 18% atomic, or less than about 15% atomic.

[0088] Notably, flowing smaller amounts of halide-containing species (e.g., less than about 20% or less than about 15% of the flow rate of the hydrocarbons) can significantly reduce the amount of hydrogen when LF power is pulsed during deposition without degrading mechanical properties. In some examples, co-flow of halide-containing species as low as 5% can significantly reduce the hydrogen content without affecting mechanical properties. This can result in a net increase in the etch selectivity of the resulting film.

[0089] The deposited amorphous carbon layer should have a relatively high density. In certain examples, the amorphous carbon layer has a density of about 1.65 to about 1.85 g / cm3. In certain examples, the amorphous carbon layer has a hardness of at least about 14 GPa, or between about 14 and about 16 GPa.

[0090] Density is defined in units of mass per volume, but direct measurement of density is not always easy. In some cases, however, more easily measurable properties can be used as proxies for density. One such property is modulus. In some examples, the amorphous carbon layer has a modulus of at least about 120 GPa, or between about 120 and about 135 GPa.

[0091] In a particular example, the amorphous carbon layer has a relatively high content of graphite-like carbon as compared to diamond-like carbon. 3 Relatively high bond content compared to sp 2 In a particular example, the amorphous carbon layer should have about 5% to about 30%, or about 10% to about 15% sp 2 The remainder of the amorphous carbon layer is made up of diamond-like sp 3 Has bonds.

[0092] In various examples, a halide-containing species is added to the process gas during deposition of the amorphous carbon film. In some examples, the halide-containing species is a fluorine-containing species and / or a chlorine-containing species. In some examples, the halide-containing species is sulfur hexafluoride. In some examples, the halide-containing species is carbon tetrafluoride. In certain examples, the deposition process includes a halide-containing species at a volumetric (approximately per mole) flow rate of about 1% to about 20% of the flow rate of the hydrocarbon precursor. In certain examples, the deposition process includes a halide-containing species at a flow rate of about 5% to about 15% of the flow rate of the hydrocarbon precursor.

[0093] In a particular example, the deposition process includes a molar flow rate of about 5 slm of an inert or chemically non-reactive gas (e.g., Ar, He, and / or N2).

[0094] In a particular example, the deposition process gas has about 3% to about 50% acetylene or other hydrocarbon precursor, about 1% to about 20% sulfur hexafluoride or other halide-containing species, and about 25% to about 96% inert gas or chemically non-reactive gas. All percentages are by volume or by molar. In a particular example, the deposition process gas has about 15% to about 25% acetylene or other hydrocarbon precursor, about 5% to about 15% halide-containing species, and about 70% to about 80% inert gas or chemically non-reactive gas. In a particular example, the inert gas or chemically non-reactive gas is argon, nitrogen, and / or helium. The percentage values ​​are based on volumetric flow rates.

[0095] In some examples, the process gas consists of acetylene and / or other carbon-containing precursors, an inert gas, and SF6 or CF4. In some examples, the process gas consists essentially of acetylene and / or other carbon-containing precursors, an inert gas, and a halide-containing species. In some examples, the flow rate of the hydrocarbon precursor is between about 100 sccm and about 200 sccm. In further examples, the process gas can include one or more other species along with acetylene and / or other carbon-containing precursors, an inert gas, and a halide-containing species.

[0096] In some instances, the hydrocarbon precursor has the formula C x H y where X is an integer between 2 and 10, and Y is an integer between 2 and 24. Examples include methane (CH4), acetylene (C2H2), ethylene (C2H4), propylene (C3H6), butane (C4H 10 ), Cyclohexane (CH 12 ), benzene (C6H6), and toluene (C7H8). In certain examples, the process gas includes propylene alone or, optionally, in combination with one or more additional hydrocarbon precursors. In certain examples, the hydrocarbon precursor is a halogenated hydrocarbon in which one or more hydrogen atoms are replaced with a halogen, particularly fluorine, chlorine, bromine, and / or iodine. In some examples, the hydrocarbon precursor has a C:H ratio of at least 1:2. In some examples, more than one hydrocarbon precursor may be used.

[0097] Although this specification primarily identifies SF6 and CF4 as the halide-containing species co-flowed for the AHM film, in some examples, the process gas may include one or more of a hypervalent phosphoryl chloride or fluoride (e.g., PCl5 or PF5), or a xenon fluoride (e.g., XeF2, XeF4, XeF6). In some examples, the halide-containing species is selected from the group consisting of SF6, CF4, a hypervalent phosphoryl chloride or fluoride, a xenon fluoride, and any combination thereof. In some examples, the halide-containing species reacts with hydrogen ions and / or hydrogen radicals during deposition of the AHM film. The halide-containing species may reduce the hydrogen content as described herein while not substantially depositing any species in the AHM film.

[0098] In some examples, the pressure in the process chamber may be about 0.1 to about 15 Torr, about 0.5 Torr to about 5 Torr, or about 1 Torr. In some examples, in a four station configuration, the high frequency ("HF", e.g., 13.56 MHz power) may be about 50 W to about 8000 W, at least about 350 W, about 400 W to about 4000 W, or about 6000 W. In some examples, in a four station configuration, the low frequency ("LF", e.g., 400 kHz power) may be about 0 to about 6000 W, about 900 to about 4000 W, or about 3450 W. In some examples, the LF power may be pulsed according to a duty cycle. In some examples, the duty cycle may be between about 10% and about 75%, at least about 10%, at least about 25%, at least about 50%, between about 50% and about 75%, or about 60%.

[0099] In other contexts, it has been observed that higher deposition temperatures result in less hydrogen in the amorphous carbon film. For hardmask applications, lower hydrogen content is desired, and therefore higher temperatures are often used. However, higher temperatures unfavorably reduce modulus and hardness, which is undesirable. In some examples, the pedestal temperature may be about 20° C. to about 750° C., or up to about 650° C., or about 550° C. to about 650° C., or about 650° C. In particular examples, the pedestal temperature is at least about 200° C., or at least about 250° C. In particular examples, the pedestal temperature is at least about 500° C. In some examples, the pedestal temperature is at least about 150° C., or between about 150° C. and about 550° C. It has been observed that temperatures significantly above 650° C. may result in undesirable plasma results, such as arcing in the chamber or degradation of the underlying film.

[0100] The deposited film should be relatively uniform across the surface of the wafer. The relative amount of uniformity or non-uniformity of the deposited film is not necessarily an inherent property of the composition of the amorphous carbon layer, but rather is strongly related to the process conditions used to deposit the amorphous carbon layer.

[0101] While not wishing to be bound by theory, it is believed that hydrogen content and other impurities reduce the etch selectivity of amorphous carbon films. Therefore, reducing the hydrogen content may improve the etch selectivity of amorphous carbon films. Halide-containing species affect the hydrogen content of AHM films. It is believed that halide-containing species react with hydrogen in the plasma to form hydrogen halides that do not etch the grown film. For example, HF is not considered a deposition species because no significant amount of fluorine is detected by RBS or solid-state FTIR in the resulting film. Thus, the presence of halide-containing species may reduce the hydrogen content of the film.

[0102] Somewhat surprisingly, it has been found that halide-containing species do not themselves etch the deposited amorphous carbon film, or at least not to a large extent. For example, sulfur hexafluoride is widely used as an etchant gas in the integrated circuit fabrication industry. Surprisingly, it has been found that in the absence of a deposited carbon layer, sulfur hexafluoride and propylene, a hydrocarbon, react to form carbon hexafluoride. This result may suggest that sulfur hexafluoride, which is widely used as an etchant gas, reacts with the forming amorphous carbon hard mask and etches it. However, this is not the case. Instead, small ratios (e.g., ratios described herein) of sulfur hexafluoride or other halide-containing species may not etch the carbon hard mask or may reduce the hydrogen content of the film with significantly reduced etching. Furthermore, as shown above in FIG. 4, the mechanical properties of films deposited using process gases containing halide-containing species may be largely similar to the mechanical properties of films deposited without such halide-containing species.

[0103] In some instances, relatively small amounts of halide-containing species can significantly reduce the hydrogen content. Figures 5 and 6 show FTIR spectra for various ratios of SF6 to CH2 (Figure 5) and CF4 to CH2 (Figure 5). As shown in Figure 5, a co-flow of SF6 at as little as 5% of the CH2 flow rate can significantly reduce the CH peak around 2925, indicating reduced hydrogen content in the film. This peak is further reduced with increasing amounts of SF6, but the increased amounts can increase sulfur and fluorine incorporation in the film. Figure 6 similarly shows the CH peak reduced with the addition of as little as 5% CF4 to the process gas flow.

[0104] The examples can be performed in a plasma enhanced chemical vapor deposition (PECVD) reactor. Such a reactor can take many different forms. Furthermore, the various examples can be performed on a multi-station tool or a single station tool.

[0105] Generally, the apparatus includes one or more chambers or one or more reactors, each including one or more stations. The chambers accommodate one or more wafers and are suitable for wafer processing. The one or more chambers maintain the wafer in a defined position or positions by preventing rotation, vibration, or other agitation. In some examples, the wafer undergoing AHM deposition is transported from one station to another within the chamber during the process. For example, a 2000 Å AHM deposition may occur entirely in one station, or a 500 Å film may be deposited at each of four stations, depending on various examples. Alternatively, any other fraction of the total film thickness may be deposited at any number of stations. In various examples where multiple AHMs are deposited, multiple stations may be used to deposit each AHM layer. During processing, each wafer is held in place by a pedestal, a wafer chuck, and / or other wafer holding device. For certain operations that heat the wafer, the apparatus may include a heater, such as a heating plate.

[0106] 7 illustrates generally one example of a processing station 700 that may be used to deposit material using plasma enhanced chemical vapor deposition (PECVD). For simplicity, the processing station 700 is illustrated as a stand-alone processing station having a processing chamber body 702 for maintaining a low pressure environment. However, it will be understood that multiple processing stations 700 may be included in a common processing tool environment. Additionally, it will be understood that in some examples, one or more hardware parameters of the processing station 700, including those discussed in detail below, may be programmatically adjusted by one or more computer controllers.

[0107] The processing station 700 is in fluid communication with a reactant delivery system 701 for delivering process gases to a distribution showerhead 706. The reactant delivery system 701 includes a mixing vessel 704 for formulating and / or conditioning process gases for delivery to the showerhead 706. One or more mixing vessel inlet valves 720 may control the introduction of process gases to the mixing vessel 704. Similarly, a showerhead inlet valve 705 may control the introduction of process gases to the showerhead 706.

[0108] For example, the example of FIG. 7 includes a vaporization point 703 for vaporizing a liquid reactant that is supplied to a mixing vessel 704. In some examples, the vaporization point 703 may be a heated vaporizer. The reactant vapor generated by such a vaporizer may condense in the downstream delivery piping. Exposure of incompatible gases to the condensed reactants may generate small particles. These small particles may, for example, clog the piping, interfere with the operation of valves, or contaminate the substrate. Some approaches to address these issues include sweeping and / or evacuating the delivery piping to remove residual reactants. However, sweeping the delivery piping may lengthen the cycle time of the processing station and reduce the throughput of the processing station. Thus, in some examples, the delivery piping downstream of the vaporization point 703 may be heat traced. In some examples, the mixing vessel 704 may also be heat traced. In one non-limiting example, the piping downstream of vaporization point 703 has a ramped temperature profile at mixing vessel 704 from approximately 100° C. to approximately 150° C.

[0109] In some examples, the reactant liquid may be vaporized in a liquid injector. For example, the liquid injector may inject a pulse of liquid reactant into the carrier gas flow upstream of the mixing vessel. In one scenario, the liquid injector may vaporize the reactant by flashing the liquid from a higher pressure to a lower pressure. In another scenario, the liquid injector may atomize the liquid into spray droplets that are then vaporized in a heated delivery tubing. It will be appreciated that smaller droplets may vaporize faster than larger droplets, reducing the delay between injection and complete vaporization of the liquid. Faster vaporization may reduce the length of tubing downstream of the vaporization point 703. In one scenario, the liquid injector may be attached directly to the mixing vessel 704. In another scenario, the liquid injector may be attached directly to the showerhead 706.

[0110] In some examples, a liquid flow controller upstream of the vaporization point 703 may be provided to control the mass flow rate of liquid for vaporization and delivery to the processing station 700. For example, the liquid flow controller (LFC) may include a thermal mass flow meter (MFM) located downstream thereof. A plunger valve of the LFC may then be adjusted in response to a feedback control signal provided by a proportional-integral-derivative (PID) controller in electrical communication with the MFM. However, stabilizing the liquid flow using feedback control may take more than a second. This may extend the time to dose the liquid reactant. Thus, in some examples, the LFC may be dynamically switched between a feedback control mode and a direct control mode. In some examples, the LFC may be dynamically switched from the feedback control mode to the direct control mode by disabling the sensing tube and the PID controller of the LFC.

[0111] 7, the substrate 712 is shown positioned below the showerhead 706 and resting on a pedestal 708. It will be understood that the showerhead 706 may have any suitable shape and may have any suitable number and arrangement of ports for distributing process gases to the substrate 712.

[0112] In some examples, a microvolume 707 is located below the showerhead 706. By performing ALD and / or CVD processes in the microvolume rather than in the entire volume of the processing station, for example, reactant exposure and sweep times can be reduced, time to change process conditions (e.g., pressure, temperature, etc.) can be reduced, and exposure of processing station robotics to process gases can be limited. Examples of microvolume sizes include, but are not limited to, volumes between 0.1 liters and 2 liters. This microvolume also impacts productivity throughput. While the deposition rate per cycle is reduced, cycle time is also reduced at the same time. In certain cases, the latter effect is dramatic enough to improve the overall throughput of the module for a given target film thickness.

[0113] In some examples, the pedestal 708 may be raised or lowered to expose the substrate 712 to the microvolume 707 and / or to change the volume of the microvolume 707. For example, during a substrate transfer phase, the pedestal 708 may be lowered to allow the substrate 712 to be loaded onto the pedestal 708. During a deposition process phase, the pedestal 708 may be raised such that the substrate 712 is positioned within the microvolume 707. In some examples, the microvolume 707 may completely surround the substrate 712, as well as a portion of the pedestal 708, forming a region of high flow impedance during the deposition process.

[0114] Optionally, during a portion of the deposition process, the pedestal 708 may be lowered and / or raised to adjust the process pressure, reactant concentration, etc., within the microvolume 707. In one scenario where the process chamber body 702 remains at a base pressure during the deposition process, the pedestal 708 may be lowered to allow evacuation of the microvolume 707. Examples of ratios of the microvolume to the process chamber volume include, but are not limited to, volume ratios between 1:700 and 1:10. It will be appreciated that in some examples, the height of the pedestal may be programmatically adjusted by a suitable computer controller.

[0115] In another scenario, the height of the pedestal 708 may be adjusted to allow for changes in plasma density during plasma activation and / or treatment cycles involved in the deposition process. At the end of a deposition process stage, the pedestal 708 may be lowered to allow the substrate 712 to be removed from the pedestal 708 for another substrate transfer stage.

[0116] Although the micro-volume variations described herein refer to a height-adjustable pedestal, it will be understood that in some examples, the position of the showerhead 706 may be adjusted relative to the pedestal 708 to vary the volume of the micro-volume 707. Further, it will be understood that the vertical position of the pedestal 708 and / or the showerhead 706 may be varied by any suitable mechanism within the scope of the present disclosure. In some examples, the pedestal 708 may include a rotation axis for rotating the orientation of the substrate 712. It will be understood that in some examples, one or more of these adjustments may be programmatically performed by one or more suitable computer controllers.

[0117] Returning to the example shown in FIG. 7, the showerhead 706 and pedestal 708 are in electrical communication with an RF power supply 714 and a matching network 716 to power the plasma. In some examples, the plasma energy may be controlled by controlling one or more of the process station pressure, gas concentration, RF source power, RF source frequency, and plasma power pulse timing. For example, the RF power supply 714 and the matching network 716 may be operated at any suitable power to generate a plasma having a desired composition of radical species. Examples of suitable powers are listed above. Similarly, the RF power supply 714 may provide RF power of any suitable frequency. In some examples, the RF power supply 714 may be configured to control the high frequency RF power source and the low frequency RF power source independently of each other. Examples of low frequency RF frequencies may include, but are not limited to, frequencies between 50 kHz and 700 kHz. Examples of high frequency RF frequencies may include, but are not limited to, frequencies between 1.8 MHz and 2.45 GHz. It will be appreciated that any suitable parameters may be adjusted, either discretely or continuously, to provide plasma energy for surface reactions. In one non-limiting example, the plasma power may be pulsed to reduce ion bombardment to the substrate surface compared to a continuously powered plasma.

[0118] In some examples, the plasma may be monitored in situ by one or more plasma monitors. In one scenario, the plasma power may be monitored by one or more voltage, current sensors (e.g., VI probes). In another scenario, the plasma density and / or process gas concentration may be measured by one or more optical emission spectroscopy (OES) sensors. In some examples, one or more plasma parameters may be programmatically adjusted based on measurements from such in situ plasma monitors. For example, OES sensors may be used in a feedback loop to provide programmatic control of the plasma power. It will be appreciated that in some examples, other monitors may be used to monitor the plasma or other process characteristics. Examples of such monitors may include, but are not limited to, infrared (IR) monitors, acoustic monitors, and pressure transducers.

[0119] In some examples, the plasma may be controlled via input / output control (IOC) sequence instructions. In one example, instructions for setting plasma conditions for a plasma process step may be included in a corresponding plasma activation recipe step in a deposition process recipe. In some cases, process recipe steps may be sequentially arranged such that all instructions for a deposition process step are executed simultaneously with that process step. In some examples, instructions for setting one or more plasma parameters may be included in a recipe step preceding a plasma process step. For example, a first recipe step may include instructions for setting a flow rate of an inert gas and / or a hydrocarbon precursor gas, instructions for setting a plasma generator to a power setting, and a time delay instruction for the first recipe step. A second, subsequent recipe step may include instructions for enabling the plasma generator and a time delay instruction for the second recipe step. A third recipe step may include instructions for disabling the plasma generator and a time delay instruction for the third recipe step. It will be understood that these recipe steps may be further subdivided and / or repeated in any suitable manner within the scope of the present disclosure.

[0120] In some examples, the pedestal 708 may be temperature controlled via a heater 710. Additionally, in some examples, pressure control for the deposition processing station 700 may be provided by a butterfly valve 718. As shown in the example of FIG. 7, the butterfly valve 718 throttles and regulates the vacuum provided by a downstream vacuum pump (not shown). However, in some examples, pressure control of the processing station 700 may be adjusted by varying the flow rate of one or more gases introduced to the processing station 700.

[0121] As described above, a stack of alternating layers of materials used to form a three-dimensional (3D) integrated circuit may also be referred to as a mold stack. Examples of mold stacks include an ONON (silicon oxide-silicon nitride) stack and an OPOP (silicon oxide-polycrystalline silicon (polysilicon)) stack. An intermediate step in the 3D memory fabrication process may include etching high aspect ratio (HAR) structures into the 3D memory mold stack using a directional etching process such as reactive ion etching (RIE). A carbon hard mask may be employed to protect the surrounding substrate surface during the directional etching process.

[0122] Because the HAR feature etch process may require etching through a relatively large number of material layers, there is a risk that a carbon hard mask with poor etch selectivity will be completely consumed before the HAR feature etch process is complete. FIGS. 8A-8E illustrate structures formed in an exemplary process for etching a 3D memory mold stack utilizing a carbon hard mask with poor etch selectivity. First, FIG. 8A illustrates a mold stack 800 formed on a substrate 801. The mold stack 800 includes alternating layers of a first material 802 and a second material 804. As discussed above, in some examples, the first material 802 can include silicon oxide and the second material 804 can include silicon nitride. In other examples, the first material 802 can include silicon oxide and the second material 804 can include polysilicon. In further examples, the first material 802 and the second material 804 can include any other suitable pair of materials.

[0123] FIG. 8B shows the mold stack 800 after deposition of a carbon hardmask 806. The carbon hardmask 806 can be deposited using any suitable deposition process. Exemplary deposition processes include TCVD, PECVD, and RPECVD. The carbon hardmask can be deposited by exposing the substrate to a carbon-containing precursor in an inert or reducing environment. Exemplary carbon-containing precursors include those having the general formula C n H 2n+2 Alkanes (e.g., methane, ethane, etc.) having the general formula C n H 2n Alkenes having the general formula C n H 2n-2 Examples of carbon-containing precursors include alkynes (acetylene, propyne, etc.) having the formula: which are in the gas phase under the process conditions. Other examples of carbon-containing precursors include nitrogen-containing compounds including aliphatic and aromatic cyclic hydrocarbons, alkylamines, and oxygen-containing compounds including alcohols, ketones, esters, aldehydes, and ethers, which are in the gas phase under the process conditions.

[0124] Next, FIG. 8C shows the carbon hard mask 806 after it has been patterned. For example, the carbon hard mask 806 can be patterned by photolithography followed by an oxide etch. The patterning process removes the hard mask from regions 808 of the mold stack 800. Regions 808 are regions where the HAR features will be etched using a directional etch process. Examples of directional etch processes include sputtering, ion milling, and reactive ion etching (RIE).

[0125] During the directional etching process, the carbon hard mask 806 is also consumed. The rate at which the carbon hard mask 806 is consumed during the directional etching etch depends on the selectivity of the carbon hard mask 806. Figure 8D shows the mold stack 800 after performing a portion of the directional etching process. As can be seen, the thickness of the carbon hard mask 806 has been reduced as compared to Figure 8C.

[0126] In the case of a carbon hardmask with poor etch selectivity, the entire carbon hardmask may be consumed before the etching process of the HAR feature is complete. Figure 8E shows that the HAR feature 808 is etched halfway through the mold stack 800, while the carbon hardmask 806 is completely consumed. After the carbon hardmask 806 is consumed, the underlying mold stack layers are exposed and subject to damage from the etching process.

[0127] As one possible solution to the problem illustrated in Figures 8A-8E, a thicker carbon hardmask may be deposited. However, the patterning process may limit the thickness of the carbon hardmask. For example, a carbon hardmask that is too thick may distort the profile and shape of the features during the patterning process. Furthermore, a thicker carbon hardmask may cause more curvature in the substrate due to stress than a thinner carbon hardmask. The curvature may deteriorate the size and shape of the features during the patterning process. In addition, a thicker carbon hardmask is more susceptible to cracking than a thinner hardmask. The mechanical strength of the carbon hardmask may be characterized by its elastic modulus. The etch selectivity, stress, mechanical strength, and total thickness of the carbon hardmask layer may determine the highest aspect ratio structure that can be etched using a given carbon hardmask.

[0128] In view of the above problems, an example is disclosed regarding the use of an annealed carbon hard mask. The disclosed annealed carbon hard mask can provide higher mechanical strength, higher etch selectivity, and lower stress than a non-annealed carbon hard mask having a comparable thickness. An example provides a method of processing a substrate including a carbon hard mask on a 3D memory mold stack. The method includes placing the substrate in an annealing tool. The carbon hard mask has a first stress and a first hydrogen content. The method further includes annealing the substrate to form an annealed carbon hard mask having a second stress and a second hydrogen content. The second stress is lower than the first stress. The expressions "lower" and "higher" refer to the magnitude of stress, with the "lower" stress after annealing being less in absolute value than the "higher" stress before annealing. Additionally, the second hydrogen content is less than the first hydrogen content. After annealing, the annealed carbon hardmask can be used to etch higher aspect ratio features than a non-annealed carbon hardmask of the same thickness.

[0129] 9A-9E are schematic diagrams illustrating structures formed in an exemplary mold stack etching process using an annealed carbon hard mask. FIG. 9A illustrates a mold stack 900 formed on a substrate 901. The mold stack 900 includes alternating layers of a first material 902 and a second material 904. As discussed above, in some examples, the first material 902 can include silicon oxide and the second material 204 can include silicon nitride. In other examples, the first material 902 can include silicon oxide and the second material 904 can include polysilicon. In further examples, the first material 902 and the second material 904 can include any other suitable pair of materials.

[0130] 9B shows a carbon hardmask 906 deposited on top of the mold stack 900. As mentioned above, the carbon hardmask 906 can be deposited using any suitable deposition process. Examples include thermal CVD, PECVD, or RPECVD. Suitable carbon-containing precursors for depositing the carbon hardmask 906 include those having the general formula C n H 2n+2 Alkanes (e.g., methane, ethane, etc.) having the general formula C n H 2n Alkenes having the general formula C n H 2n-2 Examples of carbon-containing precursors include alkynes (acetylene, propyne, etc.) having the formula: ##STR00011## which are in the gas phase under process conditions. Other examples of carbon-containing precursors include aliphatic and aromatic cyclic hydrocarbons, nitrogen-containing compounds including alkylamines, and oxygen-containing compounds including alcohols, ketones, esters, aldehydes, and ethers, which are in the gas phase under process conditions. Other gases that can be used during deposition include inert gases such as argon or helium. Additionally, in some examples, hydrogen and / or nitrogen can be used.

[0131] After deposition of the carbon hard mask 906, the carbon hard mask 906 is annealed. FIG. 9C shows that the carbon hard mask 906 is transformed into an annealed carbon hard mask 907 by annealing. The annealed carbon hard mask 907 may have lower stress and less hydrogen content than the carbon hard mask 906 before annealing. The annealing may be performed under any suitable conditions. In some examples, the carbon hard mask may be annealed at a temperature in the range of 500-1000° C. Similarly, the annealing may be performed under any suitable gas environment. In some examples, the annealing is performed under an inert gas environment. Examples of inert gases include helium, neon, argon, krypton, xenon, and nitrogen. The annealing may be performed at atmospheric pressure or at a pressure lower or higher than atmospheric pressure.

[0132] The carbon hard mask 906 before annealing has a first stress and a first hydrogen content. Annealing removes hydrogen from the carbon hard mask to produce an annealed carbon hard mask having a second stress and a second hydrogen content. The second stress is lower than the first stress. The second hydrogen content is lower than the first hydrogen content. Because hydrogen-carbon bonds are terminal bonds, the presence of hydrogen-carbon bonds can change the carbon-carbon bond angle in the carbon hard mask. The changed bond angle can result in stress and resulting strain. Thus, removing hydrogen from the carbon hard mask 906 to form the annealed carbon hard mask 907 can provide a lower stress in the annealed carbon hard mask 907 than the carbon hard mask 906. Additionally, removing hydrogen from the carbon hard mask 906 can help increase the modulus of the annealed carbon hard mask 907 compared to the carbon hard mask 906 before annealing. This is because the removal of hydrogen from the carbon hard mask allows for the formation of more carbon-carbon bonds. This allows for improved etch selectivity of the annealed carbon hardmask 907 compared to the pre-annealed carbon hardmask 906.

[0133] In some examples, the stress of the annealed carbon hard mask may be 1 MPa or more and 100 MPa or less. Furthermore, in some examples, the annealed carbon hard mask after annealing may exhibit an elastic modulus of 60 GPa or more and 250 GPa or less. Additionally, in some examples, the second, lower hydrogen content may be 10 atomic percent or less. In other examples, the annealed carbon hard mask may have a stress, elastic modulus, and / or hydrogen content outside of these ranges.

[0134] In some examples, the annealing time and annealing temperature can be controlled so that the grain size of the annealed carbon hard mask as measured by Raman spectroscopy shows limited change compared to the carbon hard mask before annealing. In some examples, the change in average grain size can be 15 percent or less after annealing. In addition, annealing can reduce the sp 3 The carbon content is controllable to vary by less than 10 percent.

[0135] Next, referring to FIG. 9D, the annealed carbon hard mask 907 is patterned. In some examples, a photolithography process may be used. The patterning process removes the hard mask from regions 908. The remaining areas of the annealed carbon hard mask 907 protect the underlying mold stack 900 regions from etching.

[0136] Next, referring to FIG. 9E, a directional etching process is used to form the high aspect ratio feature 910. Any suitable directional etching method may be used. As mentioned above, examples of directional etching methods include sputtering, ion milling, and reactive ion etching (RIE). Comparing FIG. 9D to FIG. 9E, the thickness of the annealed carbon hard mask 907 decreases from FIG. 9C during the etching of the high aspect ratio feature 910 because the annealed carbon hard mask 907 is consumed. However, the etch selectivity of the annealed carbon hard mask 907 in FIG. 9 is higher than the etch selectivity of the carbon hard mask 106 in FIG. 8. This allows the directional etching to continue without completely consuming the annealed carbon hard mask 907. Next, referring to FIG. 9F, the high aspect ratio feature 910 has been completely etched without completely consuming the annealed carbon hard mask 907.

[0137] FIG. 10 is a flow diagram illustrating an exemplary method 1000 for processing a substrate. The method 1000 includes, at step 1002, placing a substrate in an annealing tool. The substrate includes a carbon hard mask having a first stress and a first hydrogen content. The method 1000 further includes, at step 1004, annealing the substrate to form an annealed hard mask. The annealed carbon hard mask has a second stress that is lower than the first stress. The annealed carbon hard mask also has a second hydrogen content that is lower than the first hydrogen content. Any suitable conditions may be used to anneal the carbon hard mask. In some examples, the substrate may be heated to a temperature within a temperature range of 500-1000° C., as shown at 1005. In other examples, the annealing may be performed at a temperature outside this range. Additionally, the annealing may be performed in any suitable gas environment. In some examples, the annealing may be performed under an inert atmosphere, as shown at 1006. Examples of suitable gases that provide an inert atmosphere during annealing include helium, neon, argon, krypton, xenon, nitrogen, and mixtures of two or more thereof. In some examples, annealing can be performed using an annealing tool that includes an annealing chamber. In other examples, a reducing agent such as hydrogen or ammonia can be used. In other examples, annealing can be performed in another type of processing chamber. For example, annealing can be performed in a deposition chamber used to deposit a carbon hardmask.

[0138] The annealing process can remove hydrogen from the carbon hard mask. In some examples, the second hydrogen content can be less than or equal to 10 atomic percent, as shown at 1008. The reduction in hydrogen content by annealing the carbon hard mask can result in the annealed carbon hard mask having a lower stress than the carbon hard mask before annealing. In some examples, the annealed carbon hard mask can have a stress of greater than or equal to 1 MPa and less than or equal to 100 MPa, as shown at 1010.

[0139] As mentioned above, the annealed carbon hard mask may have a higher carbon-carbon bond content than the carbon hard mask before annealing. The lower hydrogen content, higher carbon-carbon bond content, and lower stress of the annealed carbon hard mask may provide the annealed carbon hard mask with a higher etch selectivity than the carbon hard mask before annealing. In some examples, the annealed carbon hard mask may exhibit an elastic modulus of 60 GPa or more and 250 GPa or less, as shown at 1012. As mentioned above, a higher elastic modulus may indicate a higher mechanical strength. Thus, the annealed carbon hard mask may be less susceptible to cracking at higher stress values ​​and / or at a larger thickness compared to the non-annealed carbon hard mask.

[0140] The annealing time and annealing temperature can be controlled so that the grain size of the carbon hardmask as measured by Raman spectroscopy exhibits a relatively small change. The change in average grain size can be limited to a change of 15% or less after annealing, as shown in step 1014. In addition, the annealing can be controlled so that the sp3 carbon content of the carbon hardmask as measured by Raman spectroscopy exhibits a change of 10 percent or less, as shown in step 1016.

[0141] FIG. 11 is a flow diagram illustrating another exemplary method for processing a substrate. The method 1100 includes, at step 1102, depositing a carbon hardmask. In some examples, deposition conditions can be controlled such that the carbon hardmask exhibits an elastic modulus of 60 GPa or more and 250 GPa or less, as shown in step 1104. Controllable deposition conditions include deposition temperature, total process chamber pressure, and partial pressure of the carbon-containing precursor. The carbon hardmask can be deposited using any suitable deposition method. Examples of deposition methods include TCVD, PECVD, or RPECVD, as shown at 1106. When PECVD is used, the plasma power and plasma frequency used to deposit the carbon hardmask can also be controlled. An example of a carbon-containing precursor can be a compound of the general formula C, where n is an integer in the range of 1 to 10. n H 2n+2 Alkanes (e.g., methane, ethane, etc.) having the general formula C n H 2n Alkenes having the general formula C n H 2n-2 Examples of carbon-containing precursors include alkynes (acetylene, propyne, etc.) having the formula: which are in the gas phase under the process conditions. Other examples of carbon-containing precursors include nitrogen-containing compounds including aliphatic and aromatic cyclic hydrocarbons, alkylamines, and oxygen-containing compounds including alcohols, ketones, esters, aldehydes, and ethers, which are in the gas phase under the process conditions.

[0142] The method 1100 further includes annealing the carbon hardmask to form an annealed carbon hardmask, at step 1108. In some examples, the annealing can be performed in an annealing tool. In other examples, the annealing can be performed in another type of processing chamber. For example, the annealing can be performed in a deposition chamber used to deposit the carbon hardmask.

[0143] As discussed above, the annealing can be performed in any suitable gas environment. For example, the carbon hard mask can be annealed in an inert atmosphere, as shown at 1110. In such an example, the annealing can be performed in an atmosphere including at least one of helium, neon, argon, krypton, xenon, or nitrogen. The annealing temperature can be higher than the deposition temperature of the carbon hard mask, as shown at 1112. This aids in the removal of hydrogen and allows the carbon atoms to relax into a low stress structure after deposition. In some examples, the annealing can be performed at a temperature within a temperature range of 500-1000° C., as shown at 1114. In other examples, the annealing can be performed at a temperature outside of this range. In some examples, the annealing temperature and annealing time can be controlled such that the hydrogen content of the annealed carbon hard mask is 10 atomic percent or less, as shown at 1116. The lower hydrogen content of the annealed carbon hard mask compared to the carbon hard mask before annealing can improve the etch selectivity of the annealed carbon hard mask compared to the carbon hard mask before annealing.

[0144] Further, as discussed above, a lower hydrogen content in the annealed carbon hardmask than the carbon hardmask before annealing can provide the annealed carbon hardmask with a lower stress than the carbon hardmask before annealing. In some examples, the second stress can be greater than or equal to 1 MPa and less than or equal to 100 MPa, as shown at 1118. Further, in some examples, the annealed carbon hardmask can exhibit an elastic modulus greater than or equal to 60 GPa and less than or equal to 250 GPa, as shown at 1120. As discussed above, a higher elastic modulus can indicate a higher mechanical strength.

[0145] Additionally, the annealing time and annealing temperature can be controlled to provide limited changes in grain size as measured by Raman spectroscopy of the carbon hardmask. In some examples, the annealed carbon hardmask may provide a change in average grain size of 15% or less compared to the carbon hardmask prior to annealing, as shown at 1122. Alternatively, or in addition, the sp 3 The carbon content may show a change of 10% or less compared to the non-annealed carbon hardmask.

[0146] Continuing, the method 1100 includes patterning the annealed carbon hard mask at step 1126. The annealed carbon hard mask can be patterned using a suitable patterning process that removes the hard mask from areas where high aspect ratio features will be formed by directional etching of the underlying layer.

[0147] The method 1100 further includes, at step 1128, etching the substrate with the patterned hard mask. The etching proceeds in areas where the carbon hard mask has been removed to expose the underlying layer. Any suitable directional etching method may be used. Examples of directional etching include sputtering, ion milling, and reactive ion etching (RIE). The etch selectivity of the annealed carbon hard mask allows for etching of higher aspect ratio features than a non-annealed carbon hard mask of the same thickness.

[0148] FIG. 12 shows a block diagram of an exemplary processing tool 1200 for depositing a carbon hardmask. The processing tool 1200 may include an ALD tool or a CVD tool. The processing tool 1200 may be used to perform any of the carbon hardmask deposition processes described herein. The processing tool 1200 includes a processing chamber 1202. The processing tool 1200 further includes a substrate support 1204 for supporting a substrate 1206 within the processing chamber. The substrate support 1204 may include a pedestal, a chuck, and / or any other suitable structure. The substrate support 1204 may further include a substrate heater 1208. The processing chamber 1202 further includes a showerhead 1210. In other examples, nozzles and / or other suitable inlet hardware may be used.

[0149] The processing tool 1200 further includes one or more process gas inlets for introducing process gas into the processing chamber 1202. An example of a process gas inlet 1214 is shown. In the illustrated example, the process gas inlet 1214 directs the process gas into the showerhead 1210. The processing tool 1200 further includes flow control hardware 1216 for controlling the introduction of the process gas into the processing chamber 1202. The flow control hardware is connected to a carbon-containing precursor source 1218 and an inert gas source 1220.

[0150] The carbon-containing precursor source 1218 may include any suitable carbon-containing precursor for depositing a carbon hardmask. Examples of carbon-containing precursors include those having the general formula C, where n is an integer ranging from 1 to 10: n H 2n+2 Alkanes (e.g., methane, ethane, etc.) having the general formula C n H 2n Alkenes having the general formula C n H 2n-2Examples of carbon-containing precursors include alkynes (acetylene, propyne, etc.) having the formula: which are in the gas phase under the process conditions. Other examples of carbon-containing precursors include nitrogen-containing compounds including aliphatic and aromatic cyclic hydrocarbons, alkylamines, and oxygen-containing compounds including alcohols, ketones, esters, aldehydes, and ethers, which are in the gas phase under the process conditions.

[0151] The inert gas source 1220 may include any suitable inert gas, examples include helium, neon, argon, krypton, xenon, and nitrogen.

[0152] The processing tool 1200 further includes an exhaust system 1222. The exhaust system 1222 is configured to remove gases from the processing chamber 1202. The exhaust system 1222 may include any suitable hardware. Example hardware includes one or more low vacuum pumps and one or more high vacuum pumps.

[0153] The substrate heater 1208 can be used to provide thermal energy to facilitate the deposition process. Further, in some examples, instead or in addition, a plasma to facilitate the deposition process can be generated in the processing chamber 1202 using the matching network A1230A and a radio frequency (RF) power source A1232A. The plasma can be used to provide energy to generate gas-phase chemically active species. In the illustrated example, the processing tool 1200 is configured to form a capacitively coupled plasma. In other examples, an inductively coupled plasma, a microwave plasma, or other suitable plasma can be formed.

[0154] The matching network A1230A and the RF power source A1232A are configured to provide RF power to the showerhead 1210 as a powered electrode. The substrate support 1204 is configured as a grounded electrode. In other examples, power may be provided to the pedestal and the showerhead is grounded. The matching network A1230A, the radio frequency power source A1232A, the substrate support 1204, and the showerhead 1210 may be referred to as an in-situ plasma generator. The term "in-situ plasma" generally refers to a plasma to which the substrate 1206 is directly exposed during processing.

[0155] In some examples, a remote plasma generator 1228 can be used for a chamber cleaning process. The term "remote plasma" generally refers to a plasma formed at a location remote from the substrate being processed or the chamber surface being cleaned. Reactive species can be delivered to the processing chamber 1202 via an inlet 1231. When the optional remote plasma generator 1228 is used, the processing tool 1200 includes an RF power source B 1232B electrically connected to the remote plasma generator 1228 and a matching network B 1230B for impedance matching of the RF power source 1232B. Additionally, in some examples, a remote plasma can be used to form a carbon hard mask.

[0156] RF power source A 1232A and RF power source B 1232B can be configured for any suitable frequency and power. Examples of suitable frequencies include 400 kHz, 13.56 MHz, 27 MHz, 60 Mz, and 90 MHz. Examples of suitable powers include powers between 50 W (watts) and 50 kW. In some examples, RF power sources 1232A and 1232B can be configured to operate at multiple different frequencies and / or powers. For example, either or both RF power sources can be configured as a dual frequency radio frequency plasma source as disclosed herein.

[0157] The flow control hardware 1216 is controllable to flow process chemicals from sources 1218 and 1220 into the process chamber 1202 through the process gas inlet 1214 to form a process gas. In some examples, the flow control hardware 1216 can also be configured to control the flow of one or more chemicals into a remote plasma generator 1228. The flow control hardware 1216 generally represents any suitable elements associated with flowing gases into the process chamber 1202 (and, in some examples, the remote plasma generator 1228). For example, the flow control hardware 1216 may include one or more mass flow controllers and / or valves controllable to place selected chemical sources in fluid communication with the process chamber 1202.

[0158] The controller 1236 is operatively coupled to the substrate heater 1208, the flow control hardware 1216, the remote plasma generator 1228, the exhaust system 1222, the RF source A 1232A, and the RF power source B 1232B. The controller 1236 may be further operatively coupled to any other suitable elements of the processing tool 1200. The controller 1236 is configured to control various functions of the processing tool 1200 to deposit a carbon hard mask.

[0159] For example, the controller 1236 is configured to operate the substrate heater 1208 to heat the substrate 1206. The controller 1236 is also configured to operate the flow control hardware 1216 to flow a selected chemical or mixture of chemicals at a selected rate into the process chamber 1202. The controller 1236 is also configured to operate the exhaust system 1222 to remove gases from the process chamber 1202. The controller 1236 is further configured to operate the flow control hardware 1216 and the exhaust system 1222 to maintain a selected pressure in the process chamber 1202. The controller 1236 is further configured to control the plasma source 1232A to control the plasma generated in the process chamber 1202. Additionally, the controller 1236 is configured to operate the RF power source 1232B to generate a remote plasma. In other examples, the processing tool may emit one or more of a remote plasma generator or an in-situ plasma generator.

[0160] In some examples, the controller 1236 can be configured to control the processing tool 1200 to anneal the substrate after deposition of the carbon hard mask. In such examples, the controller 1226 can be configured to heat the substrate 1206 to an annealing temperature and control the gas environment within the processing chamber 1202 for the annealing process.

[0161] However, depositing and annealing a carbon hardmask in the same processing tool, such as processing tool 1200, can increase cycle time and reduce throughput. Additionally, hardware components on processing tool 1200 can deteriorate faster due to the longer processing time at elevated temperatures caused by annealing. Also, in some instances, the substrate heater may not be able to heat to a high enough temperature for the annealing process.

[0162] Thus, in other examples, annealing can be performed in an annealing tool. The annealing tool can be designed to withstand higher temperatures for longer times and provide a higher throughput than can be achieved by annealing in a deposition tool. FIG. 13 shows a block diagram of an exemplary annealing tool 1300. The annealing tool 1300 can also be referred to as a furnace. The annealing tool 1300 includes an annealing chamber 1302, a heater 1304, and a substrate support 1306. The annealing tool 1300 further includes supports 1308A, 1308B, 1308C, and 1308D that support the substrate support 1306, and an exhaust system 1310. In some examples, the substrate support 1306 can hold multiple substrates 1312.

[0163] The annealing tool 1300 further includes a gas source A 1316 and a gas source B 1318. In other examples, more or fewer gas sources can be used. Gases are delivered into the annealing chamber 1302 through a gas inlet 1320. The annealing tool 1300 further includes flow control hardware 1322 for controlling the introduction of annealing gases into the annealing chamber 1302.

[0164] Gas source A 1316 may include an inert gas. Examples include helium, neon, argon, krypton, xenon, and nitrogen. The inert gas can be provided to the annealing chamber 1302 during the annealing process. The inert gas can also be used as a purge gas for the annealing chamber 1302. In some examples, two or more inert gas sources can be used to provide two or more different inert gases to the annealing chamber 1302. Examples include a mixture of argon and nitrogen. Gas source B 1318 may optionally include a reducing gas for annealing the substrate 1312 in a reducing environment. Examples of reducing gases include H2, or a mixture of H2 and N2.

[0165] The annealing chamber 1302 is heated by a heater 1304. In some examples, heat from the heater 1304 is transferred to the annealing chamber 1302 by convection. In other examples, the heater 1304 can function as a radiative heater that heats the substrate 1312 by radiation. In some examples, the heater 1304 can be divided into multiple zones along the length of the annealing chamber 1302, with each zone being individually controllable independent of the other zones.

[0166] The exhaust system 1310 is configured to remove gases from the annealing chamber 1302. The exhaust system 1310 may include any suitable hardware. Examples of the hardware include a vacuum pump.

[0167] Flow control hardware 1322 is controllable to flow gases from gas source A 1316 and gas source B 1318 into the annealing chamber 1302 through process gas inlet 1320. The flow control hardware 1322 generally represents any suitable elements associated with flowing gases into the annealing chamber 1302. For example, the flow control hardware 1322 may include one or more mass flow controllers and / or valves controllable to place the gas sources in fluid communication with the annealing chamber 1302.

[0168] The controller 1324 is operatively coupled to the heater 1304, the flow control hardware 1322, and the exhaust system 1310. The controller 1324 may further be operatively coupled to any other suitable elements of the annealing tool 1300, such as thermocouples. The controller 1324 is configured to control various functions of the annealing tool 1300 to perform the annealing process. The controller 1324 is also configured to control various functions of the annealing tool 1300 to perform an annealing chamber cleaning process.

[0169] In further examples, the carbon hardmask can be annealed using any other suitable tool other than those shown in Figures 12 and 13. The annealed carbon hardmask according to the disclosed examples can exhibit lower hydrogen concentration, higher elastic modulus, and lower stress than a non-annealed carbon hardmask of the same thickness. This can provide the annealed carbon hardmask with a higher etch selectivity than a non-annealed carbon hardmask. Thus, the use of the annealed carbon hardmask allows etching of higher aspect ratio features than a non-annealed carbon hardmask of the same thickness.

[0170] 14 is a schematic diagram of an example of a multi-station processing tool 1400 having an input load lock 1402 and an output load lock 1404, either or both of which may include a remote plasma source. The multi-station processing tool may represent an implementation of processing tools 700 or 1200, as examples. A robot 1406 is configured to move a wafer from a cassette loaded through a pod 1408 at atmospheric pressure to the input load lock 1402 through an atmospheric port 1410. The wafer is placed on a pedestal 1412 in the input load lock 1402 by the robot 1406, the atmospheric port 1410 is closed, and the load lock is pumped down. If the input load lock 1402 includes a remote plasma source, the wafer may be exposed to a remote plasma process in the load lock before being introduced to the processing chamber 1414. Additionally, the wafer may also be heated in the input load lock 1402 to remove, for example, moisture and adsorbed gases. Next, the chamber transfer port 1416 to the processing chamber 1414 is opened and another robot (not shown) places the wafer into the reactor and onto the pedestal of the first station shown in the reactor for processing.

[0171] The illustrated processing chamber 1414 includes four processing stations, numbered 1-4 in the example shown in FIG. 14. Each station includes a heated pedestal (shown at 1418 for station 1) and a gas line inlet. It will be understood that in some examples, each processing station may have a different purpose or multiple purposes. Although the illustrated processing chamber 1414 includes four stations, it will be understood that a processing chamber according to the present disclosure may have any suitable number of stations. For example, in some examples, a processing chamber may have five or more stations, and in other examples, a processing chamber may have three or fewer stations.

[0172] FIG. 14 also illustrates an example of a wafer handling system 1490 for transporting wafers into the processing chamber 1414. In some examples, the wafer handling system 1490 may transport wafers between various processing stations and / or between processing stations and load locks. It will be understood that any suitable wafer handling system may be employed. Non-limiting examples include a wafer carousel and a wafer handling robot. FIG. 14 also illustrates an example of a system controller 1450 employed to control process conditions and hardware states of the processing tool 1400. The system controller 1450 may include one or more memory devices 1456, one or more mass storage devices 1454, and one or more processors 1452. The processor 1452 may include a CPU or computer, analog and / or digital input / output connections, stepper motor control boards, etc.

[0173] In some examples, the system controller 1450 controls all of the operations of the processing tool 1400. The system controller 1450 executes system control software 1458 stored in the mass storage device 1454, loaded into the memory device 1456, and executed on the processor 1452. The system control software 1458 may include instructions for controlling the timing, mixture of gases, chamber and / or station pressure, chamber and / or station temperature, purge conditions and timing, wafer temperature, RF power levels, RF frequency, substrate, pedestal, chuck and / or susceptor position, and other parameters of a particular process performed by the processing tool 1400. The system control software 1458 may be configured in any other suitable manner. For example, subroutines or controls for various processing tool components may be written to control the operation of the processing tool components necessary to perform the various processing tool processes according to the methods of the present disclosure. The system control software 1458 may be coded in any suitable computer readable programming language.

[0174] In some examples, the system control software 1458 may include input / output control (IOC) sequence instructions for controlling the various parameters mentioned above. In some examples, other computer software and / or programs stored on the mass storage device 1454 and / or memory device 1456 associated with the system controller 1450 may be employed. Examples of programs or sections of programs for this purpose include a substrate positioning program, a process gas control program, a pressure control program, a heater control program, and a plasma control program.

[0175] The substrate positioning program may include program code for the processing tool components used to load the substrate onto the pedestal 1418 as well as control the spacing between the substrate and other parts of the processing tool 1400.

[0176] The process gas control program may include code for controlling the composition and flow rates of gases and, optionally, for flowing gases into one or more process stations prior to deposition to stabilize the pressure in the process station. The process gas control program may include code for controlling the composition and flow rates of gases within any of the scopes of the present disclosure. The pressure control program may include code for controlling the pressure in the process station by, for example, adjusting a throttle valve in the exhaust system of the process station, the flow of gas into the process station, etc. The pressure control program may include code for maintaining the pressure in the process station within any of the pressure ranges of the present disclosure.

[0177] The heater control program may include code for controlling current to a heating unit used to heat the substrate. Alternatively, the heater control program may control the delivery of a heat transfer gas (such as helium) to the substrate. The heater control program may include instructions for maintaining the temperature of the substrate within any of the scopes of the present disclosure.

[0178] The plasma control program may include code for setting the level and frequency of RF power applied to the process electrodes in one or more processing stations using, for example, any of the RF power levels disclosed herein. The plasma control program may also include code for controlling the duration of each plasma exposure.

[0179] In some examples, there may be a user interface associated with the system controller 1450. The user interface may include a display screen, a graphical software display of equipment and / or process conditions, and user input devices such as a pointing device, keyboard, touch screen, microphone, etc.

[0180] In some examples, the parameters adjusted by the system controller 1450 may relate to process conditions. Non-limiting examples include process gas composition and flow rates, temperature, pressure, plasma conditions (e.g., RF power levels, frequency, and exposure time), etc. These parameters may be provided to a user in the form of a recipe, which may be entered using a user interface.

[0181] Signals for monitoring the process may be provided by analog and / or digital input connections of the system controller 1450 from various process tool sensors. Signals for controlling the process may be output on analog and digital output connections of the process tool 1400. Non-limiting examples of process tool sensors that may be monitored include mass flow controllers, pressure sensors (such as manometers), thermocouples, etc. Appropriately programmed feedback and control algorithms may be used to maintain process conditions using data from these sensors.

[0182] Any suitable chamber may be used to carry out the disclosed examples. In some examples, two or more stations may perform the same function. Similarly, two or more stations may perform different functions. Each station can be designed / configured to perform a particular function / method as desired.

[0183] FIG. 15 is a block diagram of an exemplary modular cluster processing system suitable for performing substrate processing according to certain examples. The system 1500 includes a transfer module 1503. The transfer module 1503 provides a clean, pressurized environment to minimize the risk of contamination of the substrate during processing as the substrate moves between various reactor modules. Two multi-station reactors 1509 and 1510 are mounted on the transfer module 1503, each of which can perform atomic layer deposition (ALD) and / or chemical vapor deposition (CVD) according to certain examples. The reactors 1509 and 1510 can include multiple stations 1511, 1513, 1515, and 1517 that can perform operations in a continuous or non-continuous manner according to disclosed examples. The stations can include a heated pedestal or substrate support, one or more gas inlets or showerheads or distribution plates. The multi-station processing tool 1400 is an example of the multi-station reactors 1509 and 1510.

[0184] The transfer module 1503 may also be fitted with one or more single or multi-station modules 1507 capable of performing plasma pre-cleaning or chemical (non-plasma) pre-cleaning or any other process described in connection with the disclosed method. The modules 1507 may be used for various processes, in some cases, to prepare the substrate for, for example, a deposition process. The modules 1507 may also be designed / configured to perform various other processes, such as etching, polishing, or annealing. The system 1500 also includes one or more wafer source modules 1501 in which wafers are stored before and after processing. An atmospheric robot (not shown) in the atmospheric transfer chamber 1519 may first retrieve the wafer from the source module 1501 to the load lock 1521. A wafer transport device (typically a robot arm unit) in the transfer module 1503 moves the wafer from the load lock 1521 to and between modules attached to the transfer module 1503.

[0185] In various examples, a system controller 1529 is employed to control process conditions during deposition. The controller 1529 typically includes one or more memory devices and one or more processors. The processor may include a CPU or computer, analog and / or digital input / output connections, stepper motor control boards, etc.

[0186] The controller 1529 may control all of the operations of the deposition apparatus. The system controller 1529 executes system control software that includes sets of instructions for controlling the timing, mixture of gases, chamber pressure, chamber temperature, wafer temperature, radio frequency (RF) power levels, wafer chuck and / or pedestal position, and other parameters of a particular process. In some examples, other computer programs stored on memory devices associated with the controller 1529 may be employed.

[0187] Typically, there is a user interface associated with the controller 1529. The user interface may include a display screen, a graphical software display of equipment and / or process conditions, and user input devices such as a pointing device, keyboard, touch screen, microphone, etc.

[0188] The system control logic may be configured in any suitable manner. In general, the logic may be designed or configured in hardware and / or software. The instructions for controlling the drive circuits may be hard-coded or provided as software. The instructions may be provided by "programming". Such programming is understood to include any form of logic, including logic hard-coded into digital signal processors, application specific integrated circuits, and other devices that have specific algorithms implemented as hardware. Programming is also understood to include software or firmware instructions that may be executed on a general purpose processor. The system control software may be coded in any suitable computer readable programming language.

[0189] The controller parameters relate to process conditions such as, for example, process gas composition and flow rates, temperature, pressure, cooling gas pressure, substrate temperature, and chamber wall temperature. These parameters may be provided to a user in the form of a recipe and entered using a user interface. Signals for monitoring the process may be provided by analog and / or digital input connections of the system controller 1529. Signals for controlling the process are output on analog and digital output connections of the deposition apparatus 1500.

[0190] The system software may be designed or configured in many different ways. For example, subroutines or controls for various chamber components may be written to control the operation of the chamber components necessary to perform deposition processes (and in some examples other processes) in accordance with the disclosed examples. Examples of programs or sections of programs for this purpose include substrate positioning code, process gas control code, pressure control code, and heater control code.

[0191] In some implementations, the system controller 1529 is part of a system, which may be part of the examples described above. Such a system may include semiconductor processing equipment, including one or more processing tools, one or more chambers, one or more processing platforms, and / or specific processing components (wafer pedestals, gas flow systems, etc.). These systems may be integrated with electronics to control the operation of the electronics before, during, and after processing of the semiconductor wafer or substrate. The electronics may be referred to as a "controller" that may control various parts or sub-parts of one or more systems. The system controller 1529 may be programmed to control any of the processes disclosed herein depending on the processing requirements and / or type of system. Such processes may include delivery of process gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, settings of radio frequency (RF) generators in some systems, settings of RF matching circuits, frequency settings, flow settings, fluid delivery settings, position and motion settings, loading and unloading of wafers to and from the tool, and loading and unloading of wafers to and from other transport tools and / or load locks connected or coupled to the particular system.

[0192] In general, a controller may be defined as an electronic device having various integrated circuits, logic, memory, and / or software that receive instructions, issue instructions, control operations, enable cleaning operations, enable end-point measurements, etc. Integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and / or one or more microprocessors or microcontrollers that execute the program instructions (e.g., software). Program instructions may be instructions communicated to the controller in the form of various individual settings (or program files) that define operational parameters for performing a particular process on or for a semiconductor wafer or for a system. In some examples, the operational parameters may be part of a recipe defined by a process engineer to accomplish one or more processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or wafer dies.

[0193] In some implementations, the controller may be part of or coupled to a computer that is integrated, coupled, or otherwise networked to the system, or a combination thereof. For example, the controller may be in the "cloud" or be all or part of a fab host computer system, thereby enabling remote access of wafer processing. The computer may enable remote access to the system to monitor the current progress of a fabrication operation, review the history of past fabrication operations, review trends or performance metrics from multiple fabrication operations, modify parameters of a current process, set processing steps following a current process, or initiate a new process. In some examples, a remote computer (e.g., a server) may provide a process recipe to the system over a network, which may include a local network or the Internet. The remote computer may include a user interface that allows for input or programming of parameters and / or settings, which are then communicated from the remote computer to the system. In some examples, the controller receives instructions in the form of data that specify parameters for each processing step that is performed during one or more operations. It should be understood that the parameters may be specific to the type of process being performed or the type of tool that the controller is configured to couple to or control. It should be understood that the parameters may be specific to the type of process being performed or the type of tool that the controller is configured to couple to or control. Thus, as described above, the controller may be distributed, such as by including one or more separate controllers that are networked together and work toward a common purpose, such as the processes and controls described herein. An example of a controller distributed for such purposes includes one or more integrated circuits on the chamber that are located remotely (e.g., at the platform level or as part of a remote computer) and communicate with one or more integrated circuits that cooperatively control the processes on the chamber.

[0194] Exemplary systems include, but are not limited to, a plasma etch chamber or module, a deposition chamber or module, a spin rinse chamber or module, a metal plating chamber or module, a clean chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an atomic layer deposition (ALD) chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a track chamber or module, an annealing chamber or module, and any other semiconductor processing system that may be associated with or used in the fabrication and / or manufacturing of semiconductor wafers.

[0195] As described above, depending on the process step or steps being performed by the tool, the controller may communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, nearby tools, tools located throughout the factory, a main computer, another controller, or tools used to transport materials to and from containers of wafers to and from tool locations and / or load ports within a semiconductor manufacturing factory.

[0196] Although the foregoing examples have been described in some detail for clarity of understanding, it will be apparent that certain changes and modifications may be implemented within the scope of the appended claims. The examples disclosed herein may be implemented without some or all of these specific details. In other instances, well-known process operations have not been described in detail so as not to unnecessarily obscure the disclosed examples. Furthermore, although the disclosed examples are described in conjunction with specific examples, it will be understood that the specific examples are not intended to limit the disclosed examples. It should be noted that there are many alternative ways of implementing the processes, systems, and apparatus of the examples. Thus, the examples should be considered as illustrative and non-limiting, and should not be limited to the details set forth herein.

Claims

1. 1. A method for forming an ashable hardmask (AHM) film, comprising: Receiving a substrate in a processing chamber; exposing the substrate in the processing chamber to a process gas comprising one or more hydrocarbon precursors and one or more halide-containing species; depositing the AHM film on the substrate by a plasma enhanced chemical vapor deposition (PECVD) process using the process gas; Equipped with The PECVD process comprises igniting a plasma generated by a dual radio frequency (RF) plasma source including a high frequency (HF) element and a low frequency (LF) element; the power of the HF element is maintained in a non-pulsed state during deposition; A method wherein the power of the LF element is pulsed with a duty cycle between 10% and 75% during deposition.

2. 2. The method of claim 1 , wherein the one or more halide-containing species comprises a fluorine-containing species.

3. 10. The method of claim 1, wherein a flow rate of the one or more halide-containing species is between 1% and 20% of a flow rate of the one or more hydrocarbon precursors.

4. 2. The method of claim 1, wherein the power of the HF element is at least 350 W for a 300 mm wafer and the power of the LF element is 1250 W for a 300 mm wafer.

5. 10. The method of claim 1, wherein the processing chamber is at a temperature between 150° C. and 550° C. during the PECVD process.

6. 10. The method of claim 1, wherein the processing chamber is at a pressure between 0.5 torr and 5 torr during the PECVD process.

7. 10. The method of claim 1, wherein the AHM membrane has a modulus of at least 120 GPa.

8. 10. The method of claim 1, wherein the AHM film has a hardness of at least 14 GPa.

9. 10. The method of claim 1, wherein the AHM film has a hydrogen content of less than 20 atomic percent.

10. 1. A processing tool, comprising: a processing chamber; flow control hardware configured to control a flow of process chemicals into the processing chamber; Dual radio frequency plasma sources; a controller configured to control the processing tool; Equipped with The controller controls the processing tool to: the flow control hardware controls exposure of a substrate in the processing chamber to a process gas comprising one or more hydrocarbon precursors and one or more halide-containing species; The dual radio frequency plasma source comprises: Ignite a plasma including a high frequency (HF) component and a low frequency (LF) component; maintaining the power of said HF element in a non-pulsed state during deposition; A process tool controlling the power of said LF element to be pulsed with a duty cycle between 10% and 75% during deposition.

11. 11. The processing tool of claim 10, wherein the one or more halide-containing species comprises a fluorine-containing species.

12. 1. A method of processing a substrate, the substrate comprising a carbon hard mask, the method comprising: placing the substrate in an annealing tool, the carbon hard mask having a first stress and a first hydrogen content; annealing the substrate to form an annealed carbon hard mask having a second stress and a second hydrogen content; The method, wherein the second stress is less than the first stress and the second hydrogen content is less than the first hydrogen content.

13. 13. The method of claim 12, wherein the second, lesser hydrogen content of the annealed carbon hard mask is less than or equal to 10 atomic percent.

14. 13. The method of claim 12, wherein the second, lower stress of the annealed carbon hard mask is greater than or equal to 1 MPa and less than or equal to 100 MPa.

15. 13. The method of claim 12, wherein annealing the substrate such that the annealed carbon hardmask has the second, lower stress comprises annealing the substrate such that the annealed carbon hardmask exhibits an elastic modulus of greater than or equal to 60 GPa and less than or equal to 250 GPa.

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