Carbon mask deposition

Abstract

Examples are disclosed that relate to depositing a carbon mask to thicken a partially etched mask. One example includes forming a mask layer on a substrate and etching the substrate to partially form one or more etch features, where etching the substrate also results in etching the mask layer. The method further includes depositing a carbon mask over the mask layer by plasma enhanced chemical vapor deposition (PECVD) after etching a portion of the one or more etch features but before completion of etching the one or more etch features.

Description

[Background technology]

[0001] Semiconductor device manufacturing processes can involve etching high aspect ratio structures. For example, the fabrication of three-dimensional memory structures involves the formation of high aspect ratio channel holes by etching. Summary of the Invention

[0002] Examples are disclosed that relate to depositing a carbon mask to thicken a partially etched mask. One example provides a method that includes forming a mask layer on a substrate and etching the substrate to partially form one or more etch features, where etching the substrate also results in etching the mask layer. The method further includes depositing a carbon mask over the mask layer by plasma enhanced chemical vapor deposition (PECVD) after but prior to completion of the etching of the one or more etch features.

[0003] Alternatively, or in addition, in some such embodiments, depositing the carbon mask over the mask layer includes forming a plasma including a carbon-containing compound, argon, and molecular nitrogen.

[0004] Alternatively, or in addition, in some such embodiments, the carbon-containing compound comprises one or more of an alkane, an alkene, and an alkyne.

[0005] Alternatively, or in addition, in some such embodiments, the carbon-containing compound comprises one or more of a cyclic hydrocarbon, an aromatic compound, an alcohol, an aldehyde, an ester, an ether, a ketone, an alkyl halide, and an alkylamine.

[0006] Alternatively, or in addition, in some such embodiments, the plasma includes a high frequency radio frequency power component and a low frequency radio frequency power component, the low frequency radio frequency power component having a lower frequency than the high frequency radio frequency power component.

[0007] Alternatively, or in addition, in some such embodiments, the plasma further comprises a source of hydrogen.

[0008] Alternatively, or in addition, in some such embodiments, the method further comprises heating the substrate to a temperature in the range of 100-690°C.

[0009] Alternatively, or in addition, in some such embodiments, the carbon mask is deposited without a patterning step.

[0010] Alternatively, or in addition, in some such embodiments, the substrate comprises a substrate in a 3D NAND memory manufacturing process, a substrate in a 3D NOR memory manufacturing process, or a substrate in a 3D DRAM manufacturing process.

[0011] Alternatively, or in addition, in some such embodiments, the carbon mask is deposited in a single deposition step.

[0012] Another embodiment provides a method that includes obtaining a substrate including one or more etch features and a partially etched mask layer, and exposing the substrate to a plasma including a carbon-containing compound and an inert gas to deposit a carbon mask over the partially etched mask layer without a patterning step.

[0013] Alternatively, or in addition, in some such embodiments, the plasma further comprises a source of hydrogen.

[0014] Alternatively, or in addition, in some such embodiments, the carbon-containing compound comprises one or more of an alkane, an alkene, an alkyne, a cyclic hydrocarbon, an aromatic compound, an alcohol, an aldehyde, an ester, an ether, a ketone, an alkyl halide, and an alkylamine.

[0015] Alternatively, or in addition, in some such embodiments, the inert gas comprises argon.

[0016] Alternatively, or in addition, in some such embodiments, the plasma includes a high frequency radio frequency energy component and a low frequency radio frequency energy component, the low frequency radio frequency energy component having a lower frequency than the high frequency radio frequency energy component.

[0017] Another embodiment provides a processing tool. The processing tool comprises a processing chamber. The processing tool further comprises a substrate support disposed within the processing chamber. The processing tool further comprises a substrate heater disposed within the processing chamber. The processing tool further comprises a showerhead disposed within the processing chamber. The processing tool further comprises a radio frequency power source configured to provide radio frequency power to the showerhead or the substrate support. The processing tool further comprises flow control hardware configured to control gas flow from a carbon-containing compound source and an inert gas source through the showerhead to the processing chamber. The processing tool further comprises a controller operably connected to the flow control hardware and the substrate heater. The controller is configured to operate the substrate heater to heat a substrate disposed within the processing chamber. The controller is further configured to operate the flow control hardware to introduce a carbon-containing compound gas from the carbon-containing compound source to the processing chamber. The controller is further configured to operate the flow control hardware to introduce an inert gas from the inert gas source to the processing chamber. The controller is further configured to operate the radio frequency power source to provide a low frequency radio frequency energy component and a high frequency radio frequency energy component to generate a plasma comprising the carbon-containing compound gas and the inert gas to grow a carbon mask on the partially etched mask without a patterning step, the low frequency radio frequency energy component comprising a lower frequency than the high frequency radio frequency energy component.

[0018] Alternatively, or in addition, in some such embodiments, the first radio frequency energy component comprises a power between 500 and 2500 Watts and the second radio frequency energy component comprises a power between 800 and 2500 Watts.

[0019] Alternatively, or in addition, in some such embodiments, the processing tool further comprises a carbon-containing compound source, the carbon-containing compound source comprising one or more of an alkane, an alkene, an alkyne, a cyclic hydrocarbon, an aromatic compound, an alcohol, an aldehyde, an ester, an ether, a ketone, an alkyl halide, and an alkylamine.

[0020] Alternatively, or in addition, in some such embodiments, the source of carbon-containing compound includes acetylene.

[0021] Alternatively, or in addition, in some such embodiments, the processing chamber further comprises a source of inert gas, and the inert gas comprises argon. [Brief description of the drawings]

[0022] [Figure 1A] 1A-1D are schematic diagrams of various exemplary substrate structures formed during exemplary processes for etching high aspect ratio features. [Figure 1B] 1A-1D are schematic diagrams of various exemplary substrate structures formed during exemplary processes for etching high aspect ratio features. [Figure 1C] 1A-1D are schematic diagrams of various exemplary substrate structures formed during exemplary processes for etching high aspect ratio features. [Figure 1D] 1A-1D are schematic diagrams of various exemplary substrate structures formed during exemplary processes for etching high aspect ratio features. [Figure 1E] 1A-1D are schematic diagrams of various exemplary substrate structures formed during exemplary processes for etching high aspect ratio features.

[0023] [Figure 2A] FIG. 4 is a flow diagram illustrating an exemplary method for forming a carbon mask over a partially etched mask. [Figure 2B]FIG. 4 is a flow diagram illustrating an exemplary method for forming a carbon mask over a partially etched mask.

[0024] [Diagram 3] An exemplary plasma enhanced chemical vapor deposition tool.

[0025] [Figure 4] FIG. 1 is a block diagram of an exemplary computer system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] The term "alcohol" generally refers to a compound having the general formula R-OH, where R is an aryl or aliphatic group that is unsubstituted, partially substituted, or fully substituted. Alcohols may have more than one OH group (polyols), such as diols with two OH functional groups. Examples of alcohols include methanol, ethanol, and propanol.

[0027] The term "aldehyde" generally refers to an organic compound that contains a terminal carbonyl group. Aldehydes have the general formula R-CHO, where R is an unsubstituted, partially substituted, or fully substituted aryl or aliphatic group. Examples of aldehydes include formaldehyde and acetaldehyde.

[0028] The term "aliphatic" generally refers to an organic compound lacking aromatic groups.

[0029] The term "alkane" generally refers to an alkane having the general formula C n H 2n+2 and partially or fully substituted variants thereof. Examples of alkanes include methane, ethane, propane, and butane.

[0030] The term "alkene" generally refers to an organic compound containing at least one carbon-carbon double bond, as well as unsubstituted, partially substituted, and fully substituted variants thereof. Unsubstituted alkenes containing one carbon-carbon double bond include C nH 2n It has the general formula: Examples of alkenes include ethylene, propylene, and butylenes. Alkenes may have two or more carbon-carbon double bonds, such as dienes, arenes, and cumulenes.

[0031] The term "alkylamine" generally refers to a nitrogen-containing hydrocarbon compound having 1-3 alkyl substituents (including unsubstituted, partially substituted, and fully substituted alkyl substituents) and 0-2 H substituents. Alkylamines include primary amines, secondary amines, tertiary amines, and cyclic amines. Examples of alkylamines include methylamine, dimethylamine, trimethylamine, and piperidine. Alkylamines include compounds with two or more amine groups.

[0032] The term "alkyl halide" generally refers to alkane, alkene, and alkyne compounds that contain a halogen. Examples of alkyl halides include ethyl fluoride (fluoroethane), isopropyl bromide (2-bromopropane), and t-butyl chloride (2-chloro-2-methylpropane). Alkyl halides may have two or more halogen groups, such as 1,2-dichlorobutane.

[0033] The term "alkyne" generally refers to organic compounds containing at least one carbon-carbon triple bond, and partially or fully substituted variants thereof. Unsubstituted alkynes containing one carbon-carbon triple bond can be represented by the general formula C n H 2n-2 The alkynes may have more than one carbon-carbon triple bond, such as diynes, which have two carbon-carbon triple bonds.

[0034] The term "aromatic" generally refers to planar ring compounds that contain resonating pi bonds. The term "aromatic" includes homocyclic compounds in which all atoms in the ring structure are carbon, and also includes heterocyclic compounds in which one or more atoms in the ring structure are elements other than carbon (e.g., nitrogen).

[0035] The term "carbon-containing compound" generally refers to a molecular weight substance that contains carbon atoms. Examples of carbon-containing compounds that can be used to form a carbon mask in a PECVD process may include various alkanes, alkenes, alkynes, cyclic hydrocarbons, aromatic compounds, alcohols, aldehydes, esters, ethers, ketones, aldehydes, alkyl halides, and alkylamines.

[0036] The term "carbon mask" generally refers to a carbon layer formed on a substrate. A carbon mask may include amorphous carbon in some embodiments. Amorphous carbon is a material that is composed of sp 2 Carbon and sp 3 The material may have nanoscale crystallites that include both carbon and silicon.

[0037] The term "chemical vapor deposition" ("CVD") generally refers to a process in which a material film is formed on a substrate by exposure of the substrate to one or more volatile precursors. The term "plasma-enhanced CVD" ("PECVD") generally refers to a process in which a plasma is used to generate reactive species from precursors for deposition.

[0038] The term "cyclic hydrocarbon" generally refers to saturated and unsaturated hydrocarbon molecules that contain closed ring structures, as well as partially or fully substituted variants thereof. Examples of cyclic hydrocarbons include aliphatic hydrocarbons such as cyclopropane and cyclobutane, as well as aromatic hydrocarbons such as benzene, toluene, xylene, and pyridine.

[0039] The term "ether" generally refers to a carbon-containing compound having the general formula RO-R', where R and R' are independently unsubstituted, partially substituted, or fully substituted aryl or aliphatic groups. Examples of ethers include cyclic ethers such as diethyl ether, anisole, and furan.

[0040] The term "ester" generally refers to a hydrocarbon compound having the general formula RC(O)OR', where R and R' are independently unsubstituted, partially substituted, or fully substituted aryl or aliphatic groups, and R may alternatively contain H (e.g., formate). Examples of esters include ethyl formate, methyl acetate, and ethyl acetate.

[0041] The term "intermediate structure" generally refers to a structure formed by an initial processing step that is modified in a subsequent processing step.

[0042] The term "ketone" generally refers to an organic compound containing a non-terminal carbonyl. Ketones have the general formula RC(O)-R', where R and R' are independently unsubstituted, partially substituted, or fully substituted aryl or aliphatic groups. Examples of ketones include acetone and methyl ethyl ketone.

[0043] The term "mask loss" generally refers to the loss of material from a mask layer during an etching process.

[0044] The term "patterning process" generally refers to a photolithography process.

[0045] 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 may be controllable to perform the chemical and / or physical processes.

[0046] The term "processing tool" generally refers to a machine that includes a processing chamber and other hardware configured to perform a process within the processing chamber.

[0047] The term "sticking coefficient" generally refers to the ratio of gas phase species that adsorb to a substrate surface relative to the number of gas phase species that impinge on the substrate surface.

[0048] The term "substrate" generally refers to any object upon which a film can be deposited.

[0049] The term "substrate support" generally refers to any structure for supporting a substrate in a processing chamber.

[0050] As noted above, semiconductor device fabrication processes may include etching of high aspect ratio structures. For example, fabrication of three-dimensional memory structures may include etching of high aspect ratio channel holes. One example of such a memory structure is a three-dimensional (3D) NAND memory based on a NOT AND logic gate configuration. Another example is a 3D NOR memory based on a NOT OR logic gate configuration. High aspect ratio structures may be formed during fabrication of 3D-DRAM (Dynamic Random Access Memory) devices.

[0051] To protect surrounding structures from damage when etching features into a substrate, a mask layer may be deposited and patterned to cover the surrounding structures. However, etching of high aspect ratio structures may also etch the mask, resulting in thinning of the mask. This may be referred to as mask loss. Mask loss may affect the outcome of the etching process. For example, mask loss may make it difficult to maintain target dimensions in the etch features.

[0052] As a more specific example, in a 3D NAND memory manufacturing process, a stack of alternating layers of a first material and a second material is formed. In some embodiments, the stack of alternating layers may include alternating layers of silicon oxide and polysilicon. In other embodiments, the stack of alternating layers may include alternating layers of silicon oxide and silicon nitride. FIG. 1A shows a schematic diagram of an exemplary substrate 100 on which a stack 102 of alternating layers of silicon oxide and silicon nitride (denoted as "ONON") is formed. Additionally, a hard mask layer 104 is formed on the stack 102. Thus, FIG. 1A represents an intermediate structure in a 3D NAND manufacturing process. Substrate 100 represents any suitable structure on which stack 102 may be formed. Similarly, hard mask layer 104 may be formed from any suitable material. In some embodiments, hard mask layer 104 comprises amorphous carbon.

[0053] To form a 3D memory structure, the hard mask layer 104 is patterned and then a high aspect ratio channel hole is etched at least partially through the stack 102. The intermediate structure in FIG. 1B represents the hard mask layer 104 after patterning. The patterning step used to define the location of the channel hole is not shown herein. Referring now to the intermediate structure in FIG. 1C, an etching process forms a channel hole 106 in the stack 102 through the hard mask layer 104. The downward arrow indicates a directional etching process. Examples of directional etching processes include reactive ion etching (RIE), sputtering, and ion milling. The hard mask layer 104 helps maintain the target dimensions of the channel hole by preventing adjacent regions of the stack 102 from being damaged during the etching process.

[0054] However, as noted above, the channel hole 106 may have a relatively high aspect ratio. For example, in some instances, the aspect ratio may be about 20:100. Considering the etch depth, the hard mask layer 104 will undergo mask loss during the etching process. As can be seen from the intermediate structure shown in FIG. 1D, the mask loss results in a thinning of the hard mask layer 104. This may affect the dimensions of the etched channel hole. It will be appreciated that similar mask loss may occur when etching high aspect ratio features other than channel holes in 3D memory devices.

[0055] Accordingly, embodiments are disclosed that relate to growing a carbon mask layer on top of another mask layer (e.g., an amorphous carbon hard mask) at an intermediate point in the etching process to restore at least some of the mask thickness lost during etching. FIG. 1E shows a carbon mask layer 108 formed on top of a thinned hard mask layer 104. The growth of the carbon mask layer 108 at an intermediate point during the etching process can help to maintain the target dimensions of the channel hole 106 during the next step of the etching process. The carbon mask layer 108 may be deposited at any suitable intermediate point in the etching process. In some embodiments, a single carbon mask layer 108 may be deposited during the etching process. In other embodiments, two or more depositions of the carbon mask layer may be performed at two or more different intermediate points in the etching process to restore the lost thickness, thereby maintaining the desired total thickness of the mask layer.

[0056] The carbon mask layer 108 may be deposited in a single cycle without a patterning step. For example, carbon mask deposition by PECVD using both low frequency radio frequency (RF) power components and high frequency RF power components can result in carbon mask formation on the top surface of the hard mask layer with little or no carbon depositing in the etch features. The terms "low frequency" and "high frequency" are interrelated. In some embodiments, the low frequency RF power component may have a frequency less than 2 MHz and the high frequency RF power component may have a frequency equal to or greater than 2 MHz. In other embodiments, the low frequency RF power component and the high frequency RF power component may have any other suitable values. In one experiment using low frequency RF power components and high frequency RF power components, a single step carbon deposition process was used to grow a carbon mask on the hard mask over a partially etched ONON stack. The hard mask had a post-etch thickness of 793.7 nanometers. The carbon mask was grown on the hard mask to a total thickness (hard mask layer + carbon mask layer) of 977.3 nanometers. The carbon mask layer was deposited by PECVD using an argon plasma. Acetylene was used as the carbon-containing compound. In some embodiments, a hydrogen source (e.g., molecular hydrogen) may be used in the carbon mask deposition process. After the carbon mask was formed, the channel holes appeared to be free of carbon. Without wishing to be bound by theory, the sticking coefficient of the carbon-containing compound under the process conditions combined with etching by argon ions in the plasma may contribute to carbon deposition that preferentially deposits on the top surface of the hard mask layer and not on the walls of the feature being etched. The use of a low frequency RF power component along with a high frequency RF power component may provide a more extensive etch than an etch using only a high frequency RF power component. This is because the addition of the low frequency RF power component creates more argon ion bombardment of the substrate than does the high frequency RF power component alone. This may help prevent net carbon growth on the walls of the feature by removing previously deposited carbon from the walls at a faster rate than carbon is deposited on the walls.

[0057] In other embodiments, the carbon mask layer 108 may be formed in multiple steps. For example, separate PECVD carbon deposition and etching steps may be used. In such an example, a carbon-containing compound may be introduced into the plasma in the carbon deposition step. An argon etching step may then be used to remove the carbon. Because the vertical growth rate of carbon on the partially etched mask is greater than the horizontal growth rate on the walls of the etched features, the etching step may remove the carbon from the walls of the etched features while allowing net vertical growth of carbon on the partially etched mask.

[0058] Any suitable carbon-containing compound may be used as a carbon source to deposit a carbon mask as disclosed herein. Examples of carbon-containing compounds include those having the general formula C n H 2n+2 (n=1-10) Alkanes (methane, ethane, etc.), with the general formula C n H 2n (n=2-10) Alkenes (ethylene, propylene, etc.), general formula C n H 2n-2The carbon-containing compounds may include alkynes (acetylene, propyne, etc.) having n=2-10, partially or fully substituted variants thereof, and other carbon-containing compounds in the gas phase under the process conditions. Examples may include cyclic hydrocarbons (aliphatic and aromatic), alcohols, aldehydes, esters, ethers, ketones, alkyl halides, and alkylamines. In yet other examples, the carbon-containing compounds may include mixtures of carbon-containing compounds. Examples of suitable cyclic hydrocarbons may include cyclobutane, cyclopentane, and cyclohexane. Examples of suitable aromatic compounds may include benzene, toluene, pyridine, and pyrimidine. Examples of suitable alcohols may include methanol, ethanol, and propanol. Examples of suitable diols may include ethylene glycol, propylene glycol, and hydroquinone. Examples of suitable aldehydes may include formaldehyde and acetaldehyde. Examples of suitable esters may include ethyl formate, methyl acetate, and ethyl acetate. Examples of suitable ethers may include aromatic ethers such as diethyl ether, anisole, and furan. Examples of suitable ketones may include acetone and methyl ethyl ketone. Examples of suitable alkyl halides may include ethyl fluoride, isopropyl bromide, and t-butyl chloride. Examples of suitable alkyl amines may include methylamine, dimethylamine, trimethylamine, piperidine, ethylenediamine, and 1,3-diaminopropane.

[0059] Similarly, any suitable process conditions may be used to form the carbon mask as disclosed. In some embodiments, the carbon mask may be formed by PECVD using argon and molecular nitrogen (N2) as plasma gases for mask deposition and a carbon-containing compound as a carbon source. In some embodiments, a hydrogen source may be used along with argon, molecular nitrogen, and a carbon-containing compound. Examples of hydrogen sources include molecular hydrogen and ammonia. Without wishing to be bound by theory, hydrogen can act as a passivator to reduce the rate of carbon film formation on surfaces where hydrogen is adsorbed. Hydrogen, in conjunction with etching by bombardment of energetic argon ions, may help to favor vertical carbon growth over lateral carbon growth. Additionally, the carbon mask may have a higher growth rate in the vertical direction (upward from the partially etched mask) than in the horizontal direction (perpendicular to the sidewalls of the etched feature). The combination of low lateral growth rate, hydrogen passivation, and etching by argon ions may help to avoid carbon deposition on surfaces within the partially etched features while allowing the carbon mask to grow vertically. Additionally, in some embodiments, carbon dioxide may be used as a gas during PECVD deposition of carbon films according to the present disclosure.

[0060] Suitable RF powers for the plasma include high frequency RF power of 800-2500 W (watts) and low frequency RF power of 500-2500 W. In other embodiments, a single RF frequency may be used to form the plasma. Suitable substrate temperatures include temperatures between 100-690° C. Suitable gas flow rates include flow rates of carbon-containing compounds (e.g., acetylene) between 500-700 standard volumetric flow rates per minute (sccm), argon between 8000-12,000 sccm, and molecular nitrogen between 0-2000 sccm. A low flow rate of carbon-containing compounds results in a low deposition rate, but may help to planarize the surface roughness of the hard mask layer. Such gas flow rates may be used to maintain any suitable pressure in the processing chamber. Examples include pressures between 1-20 Torr. In some embodiments, other gases may be used during carbon mask deposition. Examples include helium. These or other suitable process conditions may be used to form a carbon mask of any suitable thickness. Example thicknesses include thicknesses between 200 and 600 nm, in other embodiments any other suitable conditions may be used to grow a carbon mask of any other thickness.

[0061] 2A-2B show a flow diagram illustrating an example method 200 for processing a substrate that includes depositing a carbon mask over a partially etched mask layer. Referring first to FIG. 2A, the method 200 includes forming a mask layer over the substrate at step 202. The mask layer may include a carbon hard mask in some embodiments.

[0062] The method 200 further includes patterning the mask layer and etching the substrate to partially form one or more etch features at step 204. The etching of the substrate also causes the mask layer to etch slower than the etching of the substrate. Thus, the mask layer is partially etched during the etching process. In some embodiments, the one or more etch features include structures formed in a 3D NAND memory, 3D NOR memory, or 3D DRAM manufacturing process, as shown at 206. As a more specific example, the one or more etch features may include channel holes formed in a 3D NAND memory manufacturing process.

[0063] As mentioned above, mask loss caused by etching the mask layer can affect the dimensions of the etched channel hole. Thus, referring now to FIG. 2B, the method 200 includes, at step 208, etching a portion of one or more etch features and partially etching the mask layer, followed by depositing a carbon mask on the mask layer by plasma enhanced chemical vapor deposition (PECVD) without a patterning step. Depositing the carbon mask may include, at 210, forming a plasma including a carbon-containing compound and argon. A variety of carbon-containing compounds may be used. In general, a carbon-containing compound that is in a gas phase under process chamber conditions and does not contain unwanted elements may be used to form the carbon mask. Examples of carbon-containing compounds that may be used to deposit the carbon mask include one or more of alkanes, alkenes, and alkynes, as shown at 212. A more specific example is acetylene, as shown at 214. In other examples, the carbon-containing compound includes one or more of cyclic hydrocarbons, aromatic compounds, alcohols, aldehydes, esters, ethers, ketones, alkyl halides, and alkyl amines, as shown at 216.

[0064] As shown at 218, in some embodiments, the inert gas may include argon. In other embodiments, another suitable inert gas may be used in the plasma. Examples include helium, neon, krypton, and xenon. Additionally, in some embodiments, molecular nitrogen gas may be used as the inert gas, and the plasma conditions do not form reactive nitrogen species from the molecular nitrogen gas.

[0065] As noted above, in some embodiments, the plasma includes a high frequency RF power component having a frequency of 2 MHz or greater and a low frequency RF power component having a frequency of less than 2 MHz. Using the low frequency RF power component along with the high frequency RF power may provide a higher etch rate that more efficiently removes carbon from the surface within the feature being etched than using only high frequency RF power. The growth rate of the carbon mask in the vertical direction upward from the substrate may be higher than the horizontal growth rate of the carbon mask in the partially etched feature on the substrate. Thus, a net vertical growth of the carbon mask may occur while the carbon that accumulates in the partially etched feature is substantially removed.

[0066] In some embodiments, the plasma at 210 may further include a molecular hydrogen source at 222. As discussed above, hydrogen can act as a passivating agent that adsorbs to surfaces of the substrate, including surfaces within the partially etched features. Hydrogen radicals and other reactive hydrogen-containing species may be formed in the plasma and adsorb to surfaces of the substrate. This can further help prevent carbon deposition within the partially etched features by reducing the carbon deposition rate. Examples of suitable hydrogen sources include molecular hydrogen 224 and ammonia 226. Additionally, in some embodiments, molecular nitrogen (N2) may be used as an additional gas in the plasma, as shown at 227.

[0067] Any suitable process conditions may be used during the carbon mask growth. In some embodiments, the substrate may be heated to a temperature between 100 and 690° C., as shown in step 228. Additionally, in some embodiments, the total pressure in the process chamber may be maintained between 1 and 20 Torr while depositing the carbon mask, as shown in 230. As examples of other process conditions, suitable RF power for the plasma may include high frequency RF power between 800 and 2500 W and low frequency RF power between 500 and 2500 W. Suitable gas flow rates include a carbon-containing compound (e.g., acetylene) between 500 and 700 standard volumetric flow rates per minute (sccm), and an argon flow rate between 8000 and 12,000 sccm. A low flow rate of the carbon-containing compound results in a low deposition rate, but may help to planarize the surface roughness of the carbon hard mask layer. These or other suitable process conditions may be used to form a carbon mask of any suitable thickness. Example thicknesses include thicknesses between 200 and 600 nm. In other embodiments, any other suitable conditions may be used to grow a carbon mask of any other suitable thickness. As noted above, such process conditions may be used to form the carbon mask on the partially etched mask in a single deposition step at 232. In other embodiments, the carbon mask may be formed on the partially etched mask using one or more alternating deposition / etch cycles.

[0068] 3 illustrates an example processing tool 300 that may be used to perform mask recovery with carbon mask deposition according to the present disclosure. Processing tool 300 may be used, for example, to perform method 200. It will be understood that processing tool 300 is exemplary and not limiting, as other suitable tools may be used to perform the example methods disclosed herein.

[0069] The processing tool 300 takes the form of a PECVD tool comprising a deposition chamber 302. The deposition chamber 302 is configured to be maintained at a reduced pressure during the deposition process by a vacuum pumping system 304 comprising one or more pumps. The vacuum pumping system 304 is in electrical communication with a controller 306 which is configured to output control signals to the vacuum pumping system 304 and other components described below.

[0070] A substrate holder 308 and a showerhead 310 are disposed within the deposition chamber 302. A substrate 312 is shown disposed on the substrate holder 308. The substrate holder 308 includes a heater 314. The heater 314 is controlled by control signals from the controller 306 to maintain the substrate holder 308 at a desired setpoint temperature.

[0071] The substrate holder 308 is electrically grounded, and the showerhead 310 is connected to a power source 316. The power source 316 is configured to apply RF power to the showerhead 310 to form a plasma in a discharge gap 318 between the substrate holder 308 and the showerhead 310. The power source 316 receives control signals from the controller 306 to control various aspects of the applied current. In some embodiments, the power source 316 may be configured to provide RF power at multiple frequencies. For example, the power source 316 may be configured to provide RF power in a high frequency (HF) band having one or more frequencies equal to or greater than 2 megahertz (MHz). The power source 316 may be configured to provide RF power in a low frequency (LF) band having a frequency less than 2 MHz. The RF current applied by the power source 316 through the discharge gap 318 supports the carbon deposition plasma. The processing tool 300 further includes a matching network 320 disposed between the power source 316 and the showerhead 310 for impedance matching of the RF power source. In another embodiment, RF power may be supplied to the substrate holder 308 and the showerhead 310 may be grounded.

[0072] The processing tool 300 further includes flow control hardware 322 configured to flow the gas mixture through the deposition chamber 302 at reduced pressure. The flow control hardware 322 may include, for example, mass flow controllers 324, each of which provides a corresponding gas at a set flow rate controlled by a control signal from the controller 306. As described above, the gases set by the flow control hardware 322 include one or more carbon-containing compounds 326. Examples of carbon-containing compounds include those having the general formula C n H 2n+2 (n=1-10) Alkanes (methane, ethane, etc.), with the general formula C n H 2n (n=2-10) Alkenes (ethylene, propylene, etc.), general formula C n H 2n-2Examples of suitable carbon-containing compounds include alkynes (acetylene, propyne, etc.) having n=2-10, partially or fully substituted variants thereof, and other carbon-containing compounds in the gas phase under process conditions. Examples include cyclic hydrocarbons (aliphatic and aromatic), alcohols, aldehydes, esters, ethers, ketones, alkyl halides, and alkylamines. In yet other examples, the carbon-containing compound may include a mixture of carbon-containing compounds. Examples of suitable cyclic hydrocarbons may include cyclobutane, cyclopentane, and cyclohexane. Examples of suitable aromatic compounds may include benzene, toluene, pyridine, and pyrimidine. Examples of suitable alcohols may include methanol, ethanol, and propanol. Examples of suitable diols may include ethylene glycol, propylene glycol, and hydroquinone. Examples of suitable aldehydes may include formaldehyde and acetaldehyde. Examples of suitable esters may include ethyl formate, methyl acetate, and ethyl acetate. Examples of suitable ethers may include aromatic ethers such as diethyl ether, anisole, and furan. Examples of suitable ketones may include acetone and methyl ethyl ketone. Examples of suitable alkyl halides may include ethyl fluoride, isopropyl bromide, and t-butyl chloride. Examples of suitable alkyl amines may include methylamine, dimethylamine, trimethylamine, piperidine, ethylenediamine, and 1,3-diaminopropane.

[0073] The gases configured by the flow control hardware 322 also include one or more inert gases 328, such as argon. Examples of other inert gases include helium (He) and, under some process conditions, molecular nitrogen (N2). The gases configured by the flow control hardware 322 may further include one or more hydrogen sources 329, such as molecular hydrogen (H2) or ammonia (NH3).

[0074] As described above, the controller 306 of the processing tool 300 is operably connected to the vacuum pumping system 304, the heater 314, the mass flow controller 324, the power supply 316, as well as other controllable components of the processing tool 300. The controller 306 comprises at least one processor 330 and a memory 332. The memory 332 holds instructions executable by the at least one processor 330 to direct the controller 306 to perform control functions related to the manufacturing process disclosed herein, among other functions. In some embodiments, the controller 306 may be specific to the other components of the processing tool 300. In other embodiments, the controller 306 may be located remotely from the other components of the processing tool 300. In still other embodiments, the controller 306 may be distributed from proximal to distal to the processing tool 300.

[0075] 4 illustrates generally an example of a computer system 400 that may perform one or more of the processes described above. The computer system 400 is illustrated in a simplified manner. The computer system 400 may take the form of one or more personal computers, workstations, computers integrated with wafer processing tools, and / or network-accessible server computers. The controller 306 is an example of a computer system 400.

[0076] The computer system 400 includes a logic machine 402 and a storage machine 404. The computer system 400 may optionally include a display subsystem 406, an input subsystem 408, a communication subsystem 410, and / or other components not shown in FIG.

[0077] The logical machine 402 includes one or more physical devices configured to execute instructions. For example, the logical machine may be configured to execute instructions that are part of one or more applications, services, programs, routines, libraries, objects, components, data structures, or other logical constructs. Such instructions may be implemented to perform tasks, manipulate data formats, transform the state of one or more components, achieve a technical effect, or arrive at a desired result.

[0078] A logical machine may include one or more processors configured to execute software instructions. Additionally or alternatively, a logical machine may include one or more hardware or firmware logic machines configured to execute hardware or firmware instructions. The processors of the logical machine may be single-core or multi-core, and the instructions executed thereon may be configured for sequential, parallel, and / or distributed processing. Individual components of the logical machine may be distributed across two or more different devices, as desired, and the devices may be remotely located and / or configured for cooperative processing. Aspects of the logical machine may be virtualized and executed by remotely accessible networked computing devices configured in a cloud computing configuration.

[0079] Storage machine 404 includes one or more physical devices configured to hold instructions 412 executable by a logical machine to perform methods and processes described herein. When such methods and processes are performed, the state of storage machine 404 may be transformed, for example, to hold different data.

[0080] The storage machine 404 may include removable and / or internal devices. The storage machine 404 may include, among other things, optical memory (e.g., CD, DVD, HD-DVD, Blu-ray disk, etc.), semiconductor memory (e.g., RAM, EPROM, EEPROM, etc.), and / or magnetic memory (e.g., hard disk drives, floppy disk drives, tape drives, MRAM, etc.). The storage machine 404 may include volatile devices, non-volatile devices, dynamic devices, static devices, read / write devices, read-only devices, random access devices, sequential access devices, addressable devices, file addressable devices, and / or content addressable devices.

[0081] It will be appreciated that storage machine 404 may include one or more physical devices, however, aspects of the instructions described herein may instead be conveyed by a communication medium (e.g., electromagnetic signals, optical signals, etc.) that is not retained in a physical device for a finite duration.

[0082] Aspects of the logic machine 402 and storage machine 404 may be integrated into one or more hardware logic components, which may include, for example, field programmable gate arrays (FPGAs), program specific and application specific integrated circuits (PASICs / ASICs), program specific and application specific standard products (PSSPs / ASSPs), systems on chips (SOCs), and combined programmable logic devices (CPLDs).

[0083] When included, the display subsystem 406 may be used to present a visual representation of the data held in the storage machine 404. This visual representation may take the form of a graphical user interface (GUI). Just as the methods and processes described herein modify the data held in the storage machine and thus transform the state of the storage machine, the state of the display subsystem 406 may likewise be transformed to visually represent the changes in the underlying data. The display subsystem 406 may include one or more display devices using any type of technology on a computer. Such display devices may be combined with the logic machine 402 and / or the storage machine 404 in a common housing, or such display devices may be peripheral display devices.

[0084] When included, input subsystem 408 may include or be connected to one or more user input devices, such as a keyboard, mouse, or touch screen. In some embodiments, the input subsystem may include or be connected to selected natural user input (NUI) components. Such components may be integrated or peripheral components, and conversion and / or processing of input actions may be handled on-board or off-board. Examples of NUI components may include microphones for voice recognition, and infrared, color, stereo, and / or depth cameras for machine vision and / or gesture recognition.

[0085] When included, the communications subsystem 410 may be configured to communicatively couple the computer system 400 to one or more other computing devices. The communications subsystem 410 may include wired and / or wireless communications devices compatible with one or more different communications protocols. By way of example, the communications subsystem may be configured for communication over a wireless telephone network, or a wired or wireless local or wide area network. In some embodiments, the communications subsystem may enable the computer system 400 to send and receive messages to and from other devices over a network, such as the Internet.

[0086] It will be understood that the configurations and / or methods described herein are exemplary in nature, and that the specific examples should not be considered limiting, as several variations are possible. The specific routines or methods described herein may represent one or more of any number of processing strategies. As such, the various acts illustrated and / or described may be performed in the order illustrated and / or described, and in other instances may be performed in parallel or omitted. Similarly, the order of the processes described above may be altered.

[0087] The subject matter of the present disclosure includes all novel and non-obvious combinations and subcombinations of the various processes, systems, and configurations, as well as other features, functions, acts, and / or properties described herein and all equivalents thereof.

[0088] It will be understood that the configurations and / or methods described herein are exemplary in nature, and that the specific examples should not be considered limiting, as several variations are possible. The specific routines or methods described herein may represent one or more of any number of processing strategies. As such, the various acts illustrated and / or described may be performed in the order illustrated and / or described, and in other instances may be performed in parallel or omitted. Similarly, the order of the processes described above may be altered.

[0089] The subject matter of the present disclosure includes all novel and non-obvious combinations and subcombinations of the various processes, systems, and configurations, as well as other features, functions, acts, and / or properties described herein and all equivalents thereof.

Claims

1. 1. A method comprising: forming a mask layer on a substrate; Etching the substrate to partially form one or more etch features, the etching of the substrate also resulting in etching of the mask layer; depositing a carbon mask over the mask layer by plasma enhanced chemical vapor deposition (PECVD) after etching a portion of the one or more etch features and partially etching the mask layer; A method comprising:

2. 2. The method of claim 1 , The method, wherein depositing the carbon mask over the mask layer comprises forming a plasma comprising a carbon-containing compound, argon, and molecular nitrogen.

3. 3. The method of claim 2, The method, wherein the carbon-containing compound comprises one or more of an alkane, an alkene, and an alkyne.

4. 3. The method of claim 2, The method, wherein the carbon-containing compound comprises one or more of a cyclic hydrocarbon, an aromatic compound, an alcohol, an aldehyde, an ester, an ether, a ketone, an alkyl halide, and an alkylamine.

5. 3. The method of claim 2, The method, wherein the plasma comprises a high frequency radio frequency power component and a low frequency radio frequency power component, the low frequency radio frequency power component comprising a lower frequency than the high frequency radio frequency power component.

6. 3. The method of claim 2, The method, wherein the plasma further comprises a source of hydrogen.

7. 10. The method of claim 1 further comprising: The method comprises heating the substrate to a temperature of 100 to 690°C.

8. 2. The method of claim 1 , The method, wherein the carbon mask is deposited without a patterning step.

9. 2. The method of claim 1 , The method, wherein the substrate comprises a substrate in a 3D NAND memory manufacturing process, a substrate in a 3D NOR memory manufacturing process, or a substrate in a 3D Dynamic Random Access Memory (DRAM) manufacturing process.

10. 2. The method of claim 1 , The method wherein the carbon mask is deposited in a single deposition step.

11. 1. A method comprising: obtaining a substrate including one or more etch features and a partially etched mask layer; exposing the substrate to a plasma comprising a carbon-containing compound and an inert gas to deposit a carbon mask on the partially etched mask layer without a patterning step; A method comprising:

12. 12. The method of claim 11, The method, wherein the plasma further comprises a source of hydrogen.

13. 12. The method of claim 11, The method, wherein the carbon-containing compound comprises one or more of an alkane, an alkene, an alkyne, a cyclic hydrocarbon, an aromatic compound, an alcohol, an aldehyde, an ester, an ether, a ketone, an alkyl halide, and an alkylamine.

14. 12. The method of claim 11, The method of claim 1, wherein the inert gas comprises argon.

15. 12. The method of claim 11, The method, wherein the plasma comprises a high frequency radio frequency energy component and a low frequency radio frequency energy component, the low frequency radio frequency energy component comprising a lower frequency than the high frequency radio frequency energy component.

16. 1. A processing tool, comprising: a processing chamber; a substrate support disposed within the processing chamber; a substrate heater disposed within the processing chamber; a showerhead disposed within the processing chamber; a radio frequency power source configured to provide radio frequency power to the showerhead or the support; flow control hardware configured to control gas flow from a carbon-containing compound source and an inert gas source through the showerhead and into the processing chamber; a controller operably connected to the flow control hardware and to the substrate heater, operating the substrate heater to heat a substrate disposed within the processing chamber; operating the flow control hardware to introduce a carbon-containing compound gas from the carbon-containing compound source into the processing chamber; operating the flow control hardware to introduce an inert gas from the inert gas source into the processing chamber; and a controller configured to operate the radio frequency power source to provide a low frequency radio frequency energy component and a high frequency radio frequency energy component to form a plasma comprising the carbon-containing compound gas and the inert gas to grow a carbon mask on the partially etched mask without a patterning step, wherein the low frequency radio frequency energy component comprises a lower frequency than the high frequency radio frequency energy component.

17. 17. A processing tool according to claim 16, comprising: A processing tool, wherein the low frequency radio frequency energy component comprises a power of 500-2500 W and the high frequency radio frequency energy component comprises a power of 800-2500 W.

18. 17. A processing tool according to claim 16, further comprising: A process tool comprising a source of said carbon-containing compounds comprising one or more of alkanes, alkenes, alkynes, cyclic hydrocarbons, aromatic compounds, alcohols, aldehydes, esters, ethers, ketones, alkyl halides, and alkyl amines.

19. 20. A processing tool according to claim 18, comprising: The process tool, wherein the source of carbon-containing compounds comprises acetylene.

20. 17. A processing tool according to claim 16, further comprising:

13. A processing tool comprising the inert gas source, the inert gas comprising argon.

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