WO2025217031A1

WO2025217031A1 - Etching using a carbon-containing film precursor

Info

Publication number: WO2025217031A1
Application number: PCT/US2025/023411
Authority: WO
Inventors: Sagar Balagangadhara UDYAVARA; Vineet MALIEKKAL; Francis Sloan ROBERTS; Aarsh Nilesh DODHIA; Ragesh PUTHENKOVILAKAM; Kapu Sirish Reddy; Todd Schroeder
Original assignee: Lam Research Corp
Current assignee: Lam Research Corp
Priority date: 2024-04-08
Filing date: 2025-04-07
Publication date: 2025-10-16
Anticipated expiration: 2026-10-08

Abstract

Examples are disclosed that relate to etching carbon-containing films using an etching agent and a carbon-containing film precursor. This helps to etch the carbon-containing film at a higher rate on a field region of the substrate than within a feature. One example provides, on a substrate comprising a feature and a field region adjacent to the feature, a method of etching a carbon film deposited on the field region and within the feature. The method comprises forming a plasma using a gas mixture comprising an etching agent and a carbon-containing film precursor to generate reactive etching species and reactive deposition species. The method further comprises etching the carbon film at a higher rate in the field region than within the feature by depositing carbon within the feature during etching.

Description

ETCHING USING A CARBON-CONTAINING FILM PRECURSOR

BACKGROUND

[0001] Integrated device fabrication processes involve many steps of material deposition, patterning and removal to form integrated circuits on substrates. Carbon films are sometimes used within an integrated device fabrication process. Carbon films can be deposited, for example, using a chemical vapor deposition (CVD) technique such as plasma-enhanced chemical vapor deposition (PECVD). Carbon films can be etched using both reducing and oxidating plasma etching chemistries.

SUMMARY

[0002] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure.

[0003] Examples are disclosed that relate to etching carbon-containing films using an etching agent and a carbon-containing film precursor. This helps to etch the carbon-containing film at a higher rate on a field region of the substrate than within a feature. One example provides, on a substrate comprising a feature and a field region adjacent to the feature, a method of etching a carbon film deposited on the field region and within the feature. The method comprises forming a plasma using a gas mixture comprising an etching agent and a carbon-containing film precursor to generate reactive etching species and reactive deposition species. The method further comprises etching the carbon film at a higher rate in the field region than within the feature by depositing carbon within the feature during etching.

[0004] In some such examples, the plasma is a second plasma, and is formed in a second etching phase, and the method further comprises performing a first etching phase prior to the second etching phase, the first etching phase comprising forming a first plasma using the etching agent and omitting the carbon-containing film precursor to etch the carbon film in the field region. [0005] Additionally or alternatively, in some such examples, the method further comprises, in a third etching phase, forming a third plasma using the etching agent and omitting the carbon-containing film precursor to etch the carbon film within the feature. [0006] Additionally or alternatively, in some such examples, the second etching phase comprises etching a thickness of 1 to 20 nm of the carbon film in the field region. [0007] Additionally or alternatively, in some such examples, the plasma is a first plasma, and the method further comprises forming a second plasma using the carbon-containing film precursor and omitting the etching agent to deposit carbon film into the feature and in the field region.

[0008] Additionally or alternatively, in some such examples, the method further comprises performing a plurality of chemical vapor deposition (CVD) cycles. Each CVD cycle of the plurality of CVD cycles comprises forming the second plasma using the carbon-containing film precursor and omitting the etching agent to deposit the carbon film into the feature and in the field region. Each CVD cycle of the plurality of CVD cycles further comprises, after depositing the carbon film, forming the first plasma using the gas mixture comprising the etching agent and the carbon-containing film precursor to etch the carbon film at a higher rate in the field region than within the feature.

[0009] Additionally or alternatively, in some such examples, the gas mixture comprising the etching agent and the carbon-containing film precursor has a molar ratio of the carbon-containing film precursor to the etching agent of 1 :5 to 1 :20.

[0010] Additionally or alternatively, in some such examples, the etching agent comprises one or more of hydrogen or ammonia.

[0011] Additionally or alternatively, in some such examples, the etching agent comprises one or more of oxygen, carbon dioxide, sulfur dioxide, or nitrous oxide.

[0012] Additionally or alternatively, in some such examples, the carbon- containing film precursor comprises one or more of acetylene, ethylene, or propylene.

[0013] Additionally or alternatively, in some such examples, the etching the carbon film is performed at a temperature of 500 °C to 650 °C.

[0014] Another example 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 radio frequency power source configured to generate a plasma in the processing chamber. The processing tool further comprises flow control hardware configured to flow an etching agent and a carbon-containing film precursor into the processing chamber. The processing tool further comprises a controller configured to process a substrate comprising a feature and a field region adjacent to the feature. The substrate further comprises a carbon film in the field region and within the feature. The controller is configured to cause operation of the flow control hardware to flow the etching agent and the carbon-containing film precursor into the processing chamber. The controller is further configured to cause operation of the radio frequency power source to form a plasma in the processing chamber using the etching agent and the carbon-containing film precursor to generate reactive etching species and reactive deposition species in the plasma, and cause etching of the carbon film at a higher rate in the field region than within the feature by depositing carbon within the feature during etching.

[0015] In some such examples, the causing of the etching of the carbon film at the higher rate in the field region than within the feature occurs within a second etching phase, the plasma is a second plasma, and the controller is further configured to, in a first etching phase prior to the second etching phase, cause operation of the flow control hardware to flow the etching agent into the processing chamber, and cause operation of the radio frequency power source to form a first plasma using the etching agent and omitting the carbon-containing film precursor to cause etching of the carbon film in the field region.

[0016] Additionally or alternatively, in some such examples, the controller is further configured to, in a third etching phase after the second etching phase, cause operation of the flow control hardware to flow the etching agent into the processing chamber, and cause operation of the radio frequency power source to form a third plasma using the etching agent and omitting the carbon-containing film precursor to cause etching of the carbon film within the feature.

[0017] Additionally or alternatively, in some such examples, the causing of the etching of the carbon film at the higher rate in the field region than within the feature occurs within an etching phase, the plasma is a first plasma, and the controller is further configured to, in a deposition phase after the etching phase, cause operation of the flow control hardware to flow the carbon-containing film precursor into the processing chamber, and cause operation of the radio frequency power source to form a second plasma using the carbon-containing film precursor and omitting the etching agent to deposit carbon film into the feature and in the field region. [0018] Additionally or alternatively, in some such examples, the controller is configured to perform a plurality of chemical vapor deposition (CVD) cycles, each CVD cycle of the plurality of CVD cycles comprising the etching phase and the deposition phase.

[0019] Another example provides, on a substrate comprising a plurality of features and a field region adjacent to the plurality of features, a method of etching a carbon film deposited on the field region and within the plurality of features. The method comprises, in a first etching phase, forming a first plasma omitting a carbon- containing film precursor to etch the carbon film deposited on the field region. The method further comprises, in a second etching phase, forming a second plasma using a gas mixture comprising an etching agent and the carbon-containing film precursor to etch the carbon film. The method further comprises, in the second etching phase, etching the carbon film at a higher rate in the field region than within the plurality of features by depositing carbon within the plurality of features during etching. The method further comprises, in a third etching phase, forming a third plasma omitting the carbon-containing film precursor to etch the carbon film deposited within the plurality of features.

[0020] In some such examples, the second etching phase comprises etching a thickness of 1 to 20 nm of the carbon film in the field region.

[0021] Additionally or alternatively, in some such examples, the etching agent comprises one or more of hydrogen, ammonia, oxygen, carbon dioxide, sulfur dioxide, or nitrous oxide.

[0022] Additionally or alternatively, in some such examples, the carbon- containing film precursor comprises one or more of acetylene, ethylene, or propylene.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIGS. 1A-1D schematically show example substrate structures that can cause uneven carbon etch depths within different features on the substrate.

[0024] FIGS. 2A-2C schematically show example substrate structures that can cause in thickness variations in field regions in a carbon deposition process.

[0025] FIG. 3 shows a flow diagram of an example method of etching a carbon film at a higher rate in field regions than within a feature by depositing carbon within the feature during a controlled etch phase. [0026] FIGS. 4A-4D schematically show example structures formed using the method of FIG. 3.

[0027] FIG. 5 shows a graph of etch rate/deposition rate ratios for example controlled etching processes that include different proportions of film precursor.

[0028] FIG. 6 shows a flow diagram of an example method of depositing a carbon-containing film in features and on field regions of a substrate.

[0029] FIGS. 7A-7F schematically show example substrate structures formed using the method of FIG. 6, and illustrates reduced thickness variations compared to FIGS. 2A-2C.

[0030] FIG. 8 schematically shows an example processing tool.

[0031] FIG. 9 shows a block diagram of an example computing system.

DETAILED DESCRIPTION

[0032] The term “aspect ratio” generally represents a ratio of a depth of a feature of a substrate to an average width of the feature.

[0033] The term “carbon-containing film precursor” generally represents any compound that can be introduced into a processing chamber in a gas phase to form a carbon film on a substrate. Examples of carbon-containing film precursors include alkanes having a general formula CnH2n+2 where n is an integer in a range of 1 to 10, alkenes having a general formula CnEkn where n = 2 to 10, and alkynes having a general formula CnH2n-2 where n = 2 to 10, that are gas-phase under processing conditions. More specific examples include acetylene, ethylene, and propylene. Other examples of carbon-containing film precursors comprise cyclic hydrocarbons including aromatics, alkyl halides, alkyl amines, alkyl diamines, alcohols, ketones, esters, aldehydes, and ethers that are gas-phase under processing conditions.

[0034] The term “chemical vapor deposition” (CVD) generally represents a process in which a solid phase film is formed on a substrate by directing a continuous flow of one or more precursor gases over the substrate surface under conditions configured to cause the chemical conversion of the precursor gases to the film. The term “plasma-enhanced chemical-vapor deposition” (PECVD) generally represents a CVD process in which a plasma is used to facilitate the chemical conversion of one or more precursor gases to a solid phase film on a substrate. Thermal CVD (TCVD) processes utilize thermal energy to facilitate film formation. The terms “growth”, “deposition”, and variants thereof, also can be used to refer to film formation. The term “CVD tool” generally represents a machine comprising a processing chamber and other hardware configured to perform CVD processing.

[0035] The term “etch” and variants thereof generally represent a process in which a material is selectively removed from a substrate. An etch using a gas phase etchant is referred to as a “dry etch". An etch utilizing a liquid phase etchant is referred to as a "wet etch".

[0036] The term “etching agent” generally refers to a compound that can convert a material into volatile species to facilitate removal of the material from a substrate. Example oxygen-containing etching agents include molecular oxygen (O2), carbon dioxide (CO2), sulfur dioxide (SO2), and nitrous oxide (N2O). Example hydrogen-containing etching agents include molecular hydrogen (H2) and ammonia (NEE).

[0037] The term “feature” generally represents a recess defined by negative space that extends into a substrate.

[0038] The term “field regions” generally represents surfaces of a substrate adjacent to and/or between features of the substrate and/or surfaces of a substrate that are not inside a feature (such as not a sidewall or a bottom of a feature).

[0039] The term “flow control hardware” generally represents components configured to place one or more chemical sources in fluid connection with a processing chamber. Flow control hardware can comprise one or more mass flow controllers and/or valves, for example. Example chemical sources include film precursor sources, inert gas sources, and reactant gas sources.

[0040] The term “gas mixture” generally represents a mixture of two or more gases in a processing chamber during substrate processing.

[0041] The term “plasma” generally represents a gas comprising cations and free electrons.

[0042] The term “processing chamber” generally represents an enclosure in which chemical and/or physical processes are performed on substrates. The pressure, temperature and atmospheric composition within a processing chamber are controllable to perform chemical and/or physical processes.

[0043] The term “radio frequency power” generally represents oscillating electric energy in a radio frequency regime (approximately 20 kHz to 300 GHz).

[0044] The term “showerhead” generally represents a processing chemical outlet comprising a plurality of holes distributed across an area. [0045] The term “substrate” generally represents any object onto which a film can be deposited in a processing chamber.

[0046] As mentioned above, semiconductor device fabrication can involve many material deposition and etching steps to form integrated circuits on a substrate. As an example, a carbon film can be deposited onto a substrate to fill one or more features in the substrate. The carbon film also can be deposited in field regions of the substrate outside the features. The carbon film can be etched in a later processing step to remove at least some of the deposited carbon film from the field regions and/or within the features. However, carbon film deposition can occur unevenly and result in non- uniform film thickness, as described in more detail below. Non-uniform film thickness can cause problems during a subsequent etching step. For example, carbon film deposited within different features can be etched back to different depths. Non-uniform etch depths in features can lead to later problems in device fabrication, which can negatively impact the performance of the resulting integrated circuits.

[0047] FIGS. 1A-1D schematically show structures formed during an example carbon etching process that leads to uneven carbon film depths in features. Substrate 100 comprises features 102, 104. Substrate 100 further comprises a carbon film 106 (e.g., amorphous carbon) formed on substrate 100. Carbon film 106 comprises a carbon overburden 108. Carbon overburden 108 includes portions of carbon film 106 deposited over field regions 110 and over features 102, 104. As shown, the carbon overburden 108 comprises carbon film portion 106A and carbon film portion 106B. Additionally, a carbon film portion 106C is located within feature 102, and a carbon film portion 106D is located within feature 104. Voids 109A, 109B are respectively located in features 102, 104. In other examples, such voids may not be present. The voids may be filled with air (e.g., in some embodiments, carbon film is not formed where the voids are).

[0048] Carbon film 106 comprises a non-uniform thickness. As shown in FIG. 1A, carbon film portion 106A is thicker than carbon film portion 106B. The non- uniform thickness of carbon film 106 can be caused by various issues. For example, feature filling rates can be sensitive to a feature width, sometimes referred to as critical dimension (CD). In this example, feature 102 comprises a smaller width than feature 104. During deposition, the relatively smaller width of feature 102 causes feature 102 to fill faster than feature 104. As a result, feature 102 fills before feature 104 and carbon film portion 106 A can grow thicker than the carbon film portion 106B. In other examples, non-uniform film thickness can be caused by varying feature density on the substrate or processing conditions such as a non-uniform flow rate of processing chemicals or non-uniform plasma conditions.

[0049] Such nonuniformity in carbon film thickness can cause nonuniform etching within features. FIG. IB shows substrate 100 partway through an etching process to etch carbon film 106. As shown, carbon film portion 106B is etched from field region 110 of substrate 100 to expose carbon film portion 106D within feature 104. However, some of carbon film portion 106A remains in carbon overburden 108. [0050] Continuing, FIG. 1C shows carbon film 106 after further etching. Carbon film portion 106A is etched to expose carbon film portion 106C within feature 102. Additionally, carbon film portion 106D is etched within feature 104. However, the etch rate of carbon film portion 106D (reduction of film thickness as a function of time) is greater than the etch rate of carbon overburden 108. This is because there is a greater cross section of material to etch from carbon overburden 108 that from carbon film portion 106D. As a result, carbon film portion 106D in feature 104 is etched more deeply than carbon film portion 106C in feature 102.

[0051] FIG. ID shows substrate 100 after further etching carbon film portions 106C, 106D in features 102, 104. The etch depth in feature 104 is deeper than the etch depth in feature 102. Further, the difference in etch depth between carbon film portion 106C and carbon film portion 106D is greater than the difference in thickness between carbon film portion 106 A and carbon film portion 106B. Thus, the problem of nonuniformity is magnified due to faster etching within the feature. As a result of etching deeper in feature 104, the etching of carbon film portion 106D breaks through the carbon film to expose void 109B. In some embodiments, it may be desirable to maintain the void. As mentioned above, non-uniform etch depths in features can lead to later problems in device fabrication, which can negatively impact the performance of the resulting integrated circuits.

[0052] It also can be challenging to perform suitably uniform carbon etching and deposition on a substrate comprising regions of relatively higher feature density and regions of relatively lower feature density. For example, dynamic random-access memory (DRAM) structures can comprise a first region comprising a plurality of features at a first feature density, and a second region comprising a different feature density or lacking features altogether. A deposition process to deposit a carbon film in features can lead to an abrupt thickness variation between the first region (e.g., patterned region) and the second region (e.g., non-patterned region) where the film comprises an uneven thickness. This is shown schematically in FIGS. 2A-2C.

[0053] FIG. 2 A shows a substrate 200 comprising four features 202 A, 202B, 202C, 202D in a patterned region 202. Substrate 200 further comprises a field region 204 outside the patterned region 202. Field region 204 lacks features. Referring next to FIG. 2B, a plasma-enhanced chemical vapor deposition (PECVD) process is used to deposit a carbon film on substrate 200. Any suitable carbon-containing film precursor can be used. Examples include alkanes having a general formula CnH2n+2 where n is an integer in a range of 1 to 10, alkenes having a general formula CnEkn where n = 2 to 10, and alkynes having a general formula CnH2n-2 where n = 2 to 10, that are gas-phase under processing conditions. More specific examples include acetylene, ethylene, and propylene. Other examples of carbon-containing film precursors comprise cyclic hydrocarbons including aromatics, alkyl halides, alkyl amines, alkyl diamines, alcohols, ketones, esters, aldehydes, and ethers that are gas-phase under processing conditions.

[0054] The PECVD process deposits carbon film portions 206A, 206B, 206C, 206D within features 202A, 202B, 202C, 202D. Further, carbon film portion 206E is deposited onto field region 204. As features 202A, 202B, 202C, 202D are filled, carbon film portion 206E grows thicker in field region 204. Due to the volume of features 202A, 202B, 202C, 202D, carbon-containing film precursor deposited over patterned region 202 contributes relatively less carbon-containing film precursor deposited onto field regions 208A, 208B, 208C between the features. In contrast, carbon-containing film precursor deposited over field region 204 does not have features to fill, and thus leads to a thicker carbon film portion 206E.

[0055] FIG. 2C shows substrate 200 following yet further PECVD processing to deposit carbon film 206 to fill features 202A, 202B, 202C, 202D and form an overburden on the patterned region 202. Carbon film 206 is thicker in field region 204 than patterned region 202. Variations in film thickness due to differences in feature density can be referred to as “feature-density-dependent differential film growth”. Here, carbon film 206 comprises an abrupt thickness variation between the patterned region 202 and the field region 204, indicated by step 210. In other examples, the thickness differences can be more gradual. In any case, carbon film 206 lacks planarity. A non- planar film can cause problems during planarization processes and/or lead to device performance issues. [0056] Accordingly, examples are disclosed that relate to performing an etching process comprising a “controlled etch” phase. The controlled etch comprises forming a plasma using a gas mixture comprising a carbon-containing film precursor and a suitable amount of etching agent. The inclusion of a carbon-containing film precursor in the gas mixture helps deposit carbon film within the feature during etching. As a result, the carbon-containing film is etched at a higher rate in field regions of the substrate than within features. In various examples, a controlled etch phase can be performed as part of an etching process, or as part of a deposition process.

[0057] In an example etching process, the controlled etch phase can be performed to even out a film overburden. Briefly, a multiphase etching process can be performed to etch a carbon film deposited on a substrate comprising features. In a first etching phase, an etching agent is used in a plasma-based etching process to etch an overburden of the carbon film. When most of the carbon overburden is removed a controlled etch phase is initiated. The controlled etch phase comprises forming a plasma using a gas mixture comprising the etching agent and a carbon-containing film precursor. The carbon-containing film precursor is deposited on the field regions and within the features. The etching agent is consumed mostly on the field regions rather than in the features. By including a suitable amount of carbon-containing film precursor, the etch rate within the features is reduced compared to the etch rate in field regions. This allows the field region to be etched without etching substantially into the features. In some examples, etching within the features can be substantially halted while etching of the overburden on the field regions proceeds. As such, the carbon film on the field regions can be selectively removed without etching deeper into the features. This helps etch the carbon film to a more uniform thickness compared to the first etching phase. After the controlled etch phase, a third etching phase can be performed by forming a plasma using the etching agent to etch the carbon film within the features. Due to the controlled etch phase, the third etching phase can etch the carbon film to more even depth within the features than where the controlled etch phase is omitted.

[0058] In an example deposition process, the controlled etch phase can be performed alternating with deposition phases to remove excess overburden from nonpatterned regions. Briefly, a carbon film can be deposited onto a substrate comprising one or more features and a field region on the surface of the substrate adjacent to the features. The carbon film can be deposited by forming a plasma using a carbon- containing film precursor. During a controlled etch phase, a plasma is formed using a carbon-containing film precursor in addition to the etching agent. The controlled etch phase etches the carbon film on the field region at a higher rate than within the features. In this manner, carbon film in field regions can be etched to avoid excess film growth in field regions. Deposition phases and controlled etch phases can be cycled as part of a deposition process. This helps to slow the overall growth rate of the carbon film in the field region while the overall growth rate of the carbon film within the features is less affected. As such, performing one or more controlled etch phases can help to deposit a film with a more uniform thickness across field regions and feature regions. Example processes that include a controlled etching phase are described in more detail below.

[0059] The disclosed controlled etch can be performed using any suitable etching agent and any suitable carbon-containing film precursor. Example etching agents for etching carbon films include oxygen-containing etching agents and hydrogen-containing etching agents. Example oxygen-containing etching agents include molecular oxygen (O2), carbon dioxide (CO2), sulfur dioxide (SO2), and nitrous oxide (N2O). Example hydrogen-containing etching agents include molecular hydrogen (H2) and ammonia (NH3). Examples of carbon-containing film precursors include alkanes having a general formula CnH2n+2 where n is an integer in a range of 1 to 10, alkenes having a general formula CnEkn where n = 2 to 10, and alkynes having a general formula CnH2n-2 where n = 2 to 10, that are gas-phase under processing conditions. More specific examples include acetylene (C2H2), ethylene (C2H4), and propylene (CsEfc). Other examples of carbon-containing film precursors comprise cyclic hydrocarbons including aromatics, alkyl halides, alkyl amines, alkyl diamines, alcohols, ketones, esters, aldehydes, and ethers that are gas-phase under processing conditions.

[0060] As the ratio of the carbon-containing film precursor to etching agent is increased, the etching rate of the carbon film in the feature decreases relative to the etching rate on the field region. The ratio of carbon-containing film precursor to etching agent can be adjusted based on various factors such as feature width and/or feature density. In some examples, the ratio of the etching agent to the carbon-containing film precursor is based on the feature width (CD size). For a relatively larger feature width, the controlled etch phase can use a relatively greater ratio of carbon-containing film precursor to etching agent. On the other hand, for a relatively smaller feature width, the controlled etch phase can use a relatively lower ratio of carbon-containing film precursor to etching agent. In some examples, the ratio of carbon-containing film precursor to etching agent can be adjusted based on the density of features (e.g. features per pm²) on the substrate. A relatively greater ratio of carbon-containing film precursor to etching agent can be used for a relatively greater feature density than for a lesser feature density. Further, the controlled etching process also can help selectively etch a carbon film in field regions of a substrate having features comprising different sizes and/or regions with varying feature density.

[0061] FIG. 3 shows a flow diagram of an example method 300 of etching a carbon film within features on a substrate. Method 300 includes a controlled etch phase that helps achieve a relatively uniform etch depth. FIGS. 4A-4D schematically show example structures formed using method 300. At 302, method 300 comprises performing a first etching phase. The first etching phase comprises forming a first plasma using an etching agent to etch a carbon film on a field region of a substrate. Any suitable etching agent can be used. Examples include oxygen-containing etching agents, such as molecular oxygen, carbon dioxide, sulfur dioxide, and nitrous oxide. Example etching agents further include hydrogen-containing etching agents such as molecular hydrogen and ammonia.

[0062] Use of a plasma can help convert at least some etching agent to reactive species (e.g., radical species) to facilitate chemical etching of the carbon film. For example, in hydrogen-containing etching processes, radical hydrogen species can react with the carbon film to form volatile CH_X species, such as CEE. Likewise, in oxygencontaining etching processes, radical oxygen species can react with the carbon film to form CO, CO2, or CH_xO_y species. Any suitable plasma conditions can be used. Example plasma conditions include radio frequency powers of 50 to 2500 Watts (W). In other examples, higher or lower powers can be used. Unless otherwise stated, values for RF power refers to power per substrate processing station. RF power for a multi-station processing chamber can be scaled accordingly. Example frequencies for the radio frequency plasma include frequencies of 400 kHz, 13.56 MHz, 27 MHz, 60 MHz, and 90 MHz. In some examples, the plasma can comprise a higher frequency radio frequency energy component (“HF component”) and a lower frequency radio frequency energy component (“LF component”). The HF component can comprise frequencies of 3 MHz to 300 MHz. The LF component can comprise frequencies of 3 MHz and below. The HF component can comprise a radio frequency power of 50 to 6500 W. The LF component can comprise a radio frequency power of 0 to 5000 W. In some examples, the gas mixture used to form the plasma can further comprise one or more inert gases in addition to the etching agent. Examples of inert gases include helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe).

[0063] The first etching phase 302 is shown schematically in FIGS. 4A-4B. FIG. 4 A shows a substrate 400 comprising a feature 402 and a feature 404 in a different location from feature 402. Substrate 400 further comprises a carbon film 406 formed on substrate 400. Carbon film 406 can comprise amorphous carbon, for example. Carbon film 406 comprises a carbon film portion 406A over feature 402. Carbon film 406 further comprises a carbon film portion 406B over feature 404. These film portions are part of the carbon overburden 408. Additionally, carbon film portion 406C is located in feature 402 and carbon film portion 406D is located in feature 404. As shown in FIG. 4A, carbon overburden 408 comprises a non-uniform thickness as carbon film portion 406A is thicker than carbon film portion 406B. The non-uniform thickness of carbon overburden 408 can be caused by, e.g., varying feature widths and/or feature densities. [0064] FIG. 4B shows substrate 400 following first etching phase 302. As shown, almost all of carbon film portion 406B is etched from the carbon overburden 408 of substrate 400. As such, additionally etching can expose carbon film portion 406D and etch the carbon film portion 406D within the feature 404. However, some of carbon film portion 406A remains over feature 402 and in field regions 410. Due to the non-uniform thickness of carbon overburden 408, some features can be exposed during etching while other features are covered by at least some carbon overburden 408. In some examples, the first etching phase is stopped prior to exposing features so that at least some overburden remains on the field region over each feature. Referring again to FIG. 3, in some examples, at 304, the first etching phase comprises etching the overburden to a thickness of 1 to 20 nm. In other examples, a thickness outside this range can be used.

[0065] Continuing, at 306, method 300 comprises performing a second etching phase comprising a controlled etch. The second etching phase includes forming a second plasma using a gas mixture comprising an etching agent and a carbon- containing film precursor. This forms reactive etching species and reactive deposition species in the second plasma. The reactive deposition species are deposited in field regions and within the features. However, the reactive etching species are concentrated in the field regions and the top portion of the features, with decreasing concentration as a function of increasing depth with the features. As such, the combination of reactive deposition species and reactive etching species helps etch the carbon film at a higher rate in the field region than within the feature by depositing carbon within the feature during etching.

[0066] Any suitable plasma conditions, carbon-containing film precursors, and etching agents can be utilized, including those described above. The etching agent used in second etching phase 306 can be a same etching agent or a different etching agent from that used in first etching phase 302.

[0067] FIG. 4C shows substrate 400 following second etching phase 306. As described above, the second etching phase etches the carbon film 406 at a higher rate in the field region than within the features. As a result, carbon film portion 406A is removed from the carbon overburden 408 over feature 402 and in field regions 410. This exposes carbon film portion 406C within feature 402. However, carbon film portion 406D is not substantially etched. This is because carbon is deposited within feature 404 during the second etching phase 306. As such, the carbon film portions 406 A and 406B in field regions 410 can be selectively etched without etching carbon film portions 406C, 406D within features 402, 404.

[0068] As mentioned above, using relatively more carbon-containing film precursor can help etch the carbon film within the feature at a slower rate than the etching rate on the field region. In some examples, at 308, the molar ratio of carbon- containing film precursor: etching agent can be within a range of 1 :5 to 1 :20. In other examples, a ratio outside this range can be used.

[0069] FIG. 5 shows a graph comparing etch rates on a field region to etch rates within a feature using an example plasma-based etching process with different amounts of carbon-containing film precursor. Other experimental conditions, such as feature width and plasma conditions, are maintained across different trials. Graph 500 shows the ratio between the etch rate within the feature to the etch rate in field regions. The feature/field etch rate ratio decreases as the flow rate of carbon-containing film precursor increases. This indicates that adding film precursor to the plasma inhibits etching within the features to a greater extent than inhibiting etching in field regions. The feature/field etch rate ratio drops below 1 : 1 for molar ratios of carbon-containing film precursoretching agent that are within a range of 1 : 16 to 1 :8. Thus, the etch rate within the features is slower than the etch rate in field regions under conditions with sufficient carbon-containing film precursor, indicated at 502. In some examples, a flow rate of carbon-containing film precursor can be selected that results in little to no etching of the carbon film within features. In some examples, a relatively greater proportion of carbon-containing film precursor can lead to conditions for net deposition of carbon film on the substrate. Thus, a flow rate of carbon-containing film precursor can be selected that achieves a net etching of carbon film in field regions with relatively less etching within features. In some examples, as mentioned above, a selected molar ratio of carbon-containing film precursoretching agent can be within a range of 1 :5 to 1 :20. In other examples, a ratio outside this range can be used.

[0070] Returning to FIG. 3, at 310, method 300 comprises performing a third etching phase. The third etching phase comprises forming a third plasma using an etching agent. Any suitable plasma conditions can be used for third etching phase 310. Additionally, the etching agent used in third etching phase 310 can be a same etching agent or a different etching agent from that used in first etching phase 302 and/or second etching phase 306. Example plasma conditions and etching agents include those described above for first etching phase 302.

[0071] FIG. 4D shows substrate 400 following third etching phase 310. The third etching phase etches carbon film portion 406C within feature 402 and carbon film portion 406D within feature 404. The etching process does not expose either of voids 409A, 409B, in contrast to the example of FIG. ID, as the carbon film portions 406C, 406D are etched to a more uniform depth level than in the example of FIG. ID. This results from performing a second etching phase 306 to even out the carbon film prior to etching into the features.

[0072] As mentioned above, a controlled etch phase also can be performed as part of a deposition process. For example, a deposition process to fill features of a patterned region of a substrate can lead to excess film on a field region of a substrate. Performing one or more controlled etch phases can help control growth of the film on the field region. Example deposition processes that include a controlled etch phase are described with reference to FIGS. 6-7F. First, FIG. 6 shows an example method 600 for depositing a carbon film on a substrate that includes a controlled etch phase alternating with a deposition phase. The controlled etch phase utilizes a first plasma and the deposition phase utilizes a second plasma. Method 600 comprises performing one or more process cycles 602 to process a substrate. At 604, each process cycle 602 comprises performing deposition phase by forming a second plasma using a carbon- containing film precursor. This deposits a carbon film on the substrate. The carbon film deposits on field regions and within features of the substrate. Any suitable carbon- containing film precursor can be used, including the examples described above. [0073] The deposition phase 604 can be performed using any suitable plasma conditions. Example plasma conditions include radio frequency power of 50 to 6500 Watts (W). Example frequencies for the radio frequency plasma include frequencies of 400 kHz, 13.56 MHz, 27 MHz, 60 MHz, and 90 MHz. In some examples, the plasma can comprise a HF component and LF component. The HF component can comprise frequencies of 3 MHz to 300 MHz. The LF component can comprise frequencies of 3 MHz and below. In some such examples, the HF component can comprise a radio frequency power of 50 to 6500 W. Likewise, in some such examples, the LF component can comprise a radio frequency power of 0 to 5000 W. In some examples, the gas mixture used to form the plasma can further comprise one or more inert gases in addition to the carbon-containing film precursor. Examples of inert gases include helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe).

[0074] Continuing, at 606, each process cycle 602 further comprises performing a controlled etch phase 606. The controlled etch phase 606 comprises forming a first plasma using a gas mixture comprising an etching agent and a carbon- containing film precursor. Examples of suitable etching agents, carbon-containing film precursors, and plasma conditions include those listed above.

[0075] FIGS. 7A-7B schematically show example structures formed during process cycles 602. FIG. 7A shows a substrate 700 comprising a patterned region 702 and a field region 704. Within the patterned region 702, substrate 700 comprises four features 702A, 702B, 702C, 702D. Field region 704 does not have features. As shown in FIG. 7A, the features 702A, 702B, 702C, 702D are partially filled with carbon film portions 706A, 706B, 706C, 706D part way through the deposition process.

[0076] FIG. 7B shows substrate 700 following a deposition phase 604. Additional carbon film is deposited into features 702A, 702B, 702C, 702D. Carbon film also is deposited onto field regions 708A, 708B, 708C between the features. Further, carbon film also is deposited onto field region 704, forming carbon film portion 706E. As mentioned above, excess carbon film deposition in field region 704 can result in feature-density-dependent differential film growth.

[0077] FIG. 7C shows substrate 700 following a controlled etch phase 606. As described above, the controlled etch phase includes forming a plasma using a gas mixture comprising an etching agent and a carbon-containing film precursor. This forms reactive etching species and reactive deposition species in the plasma. The reactive deposition species are deposited in field region 704 and within the features 702A, 702B, 702C, 702D. However, the reactive etching species are consumed mostly on the field region 704 rather than in the features. As such, the combination of reactive species helps etch the carbon film portion 706E at a higher rate in the field region than carbon film portions 706A, 706B, 706C, 706D within the features.

[0078] Returning to FIG. 6, at 608, method 600 further comprises determining whether to perform additional process cycles 602. If “YES”, method 600 returns to deposition phase 604 to perform another process cycle 602. Any suitable number of process cycles can be performed during substrate processing. If at 608 it is determined not to perform additional process cycles 602, the method 600 can proceed to 610 and terminate.

[0079] FIG. 7D shows substrate 700 following a subsequent deposition phase 604 of an additional process cycle 602. Additional carbon film is deposited into features 702A, 702B, 702C, 702D. Further, carbon film potion 706E is deposited onto field region 704 and field regions 708A, 708B, 708C between the features.

[0080] Next, FIG. 7E shows substrate 700 following a subsequent controlled etch phase 606 of the additional process cycle 602. As described above, the controlled etch phase includes forming a plasma using a gas mixture comprising an etching agent and a carbon-containing film precursor. This forms reactive etching species and reactive deposition species in the plasma. Reactive deposition species are deposited in field region 704 and within the features 702A, 702B, 702C, 702D. As before, reactive etching species are consumed mostly in the field region 704 rather than in the features. As such, the combination of reactive species helps etch the carbon film portion 706E at a higher rate in the field region than carbon film portions 706A, 706B, 706C, 706D within the features. As described above with FIGS. 7B-7C, the controlled etch phase helps to remove carbon film portion 706E in field region 704 while avoiding negative impact to the gapfill process. Thus, repeated process cycles 602 contribute to overall growth of carbon film portions 706A, 706B, 706C, 706D within features 702A, 702B, 702C, 702D without excess deposition in field region 704.

[0081] Finally, FIG. 7F shows substrate 700 after an additional arbitrary number of process cycles 602 to fill features 702A, 702B, 702C, 702D. As shown in FIG. 7F, carbon film 706 is deposited within features 702A, 702B, 702C, 702D and over field region 704 without formation of a step. The resultant carbon film 706 is more planar than carbon film 206 of FIG. 2C. As such, performing one or more process cycles 602 including a controlled etch phase 606 can help avoid feature-density-dependent differential film growth during carbon gapfill.

[0082] FIG. 8 shows an example processing tool 800 that can be used to process a carbon film by etching and/or deposition according to the present disclosure. Processing tool 800 takes the form of a PECVD tool comprising a processing chamber 802 and a substrate support 804 within the processing chamber. The substrate support 804 is configured to support a substrate 806 disposed within processing chamber 802. The substrate support 804 comprises a substrate heater 808. In other examples, a heater can be omitted, or can be located elsewhere within processing chamber 802. Processing tool 800 further comprises a showerhead 810 for introducing processing chemicals into the processing chamber. In some examples, processing tool 800 comprises a heater configured to heat showerhead 810.

[0083] Processing tool 800 further comprises flow control hardware 812. The flow control hardware connects processing chemical source(s) to processing chamber 802. In the depicted example, flow control hardware 812 connects a carbon-containing film precursor source 816, an etching agent source 820, and an inert gas source 824 to the processing chamber. The flow control hardware 812 can include any suitable components. Examples include mass flow controllers, valves, and conduits. For example, the flow control hardware 812 can comprise one or more valves controllable to place a selected gas source or selected gas sources in fluid connection with showerhead 810. The flow control hardware 812 also can comprise one or more mass flow controllers or other controllers for controlling a mass flow rate of gas.

[0084] The carbon-containing film precursor source 816 comprises any suitable precursor compound(s) for forming a carbon film. Examples of carbon-containing film precursors include alkanes having a general formula CnH2n+2 where n is an integer in a range of 1 to 10, alkenes having a general formula CnEkn where n = 2 to 10, and alkynes having a general formula CnH2n-2 where n = 2 to 10, that are gas-phase under processing conditions (such as, acetylene, ethylene, and propylene). Other examples of carbon- containing film precursors comprise cyclic hydrocarbons including aromatics, alkyl halides, alkyl amines, alkyl diamines, alcohols, ketones, esters, aldehydes, and ethers that are gas-phase under processing conditions.

[0085] The etching agent source 820 comprises any suitable etching agent. Example etching agents for etching carbon films include oxygen-containing etching agents and hydrogen-containing etching agents. Example oxygen-containing etching agents include molecular oxygen (O2), carbon dioxide (CO2), sulfur dioxide (SO2), and nitrous oxide (N2O). Example hydrogen-containing etching agents include molecular hydrogen (H2) and ammonia (NH3).

[0086] Inert gas source 824 comprises any suitable inert gas. Examples include argon, helium, neon, krypton, and xenon.

[0087] Processing tool 800 further comprises an exhaust system 832. Exhaust system 832 is configured to exhaust gases from processing chamber 802. Exhaust system 832 can comprise any suitable hardware, including one or more low vacuum pumps, one or more high vacuum pumps, and one or more valves for controlling an exhaust flow. Together, flow control hardware 812 and exhaust system 832 can be operated to achieve a selected pressure in processing chamber 802 during substrate processing. Example pressures include pressures of 1 Torr to 20 Torr. Further, exhaust system 832 can be operated to purge processing chamber 802.

[0088] Processing tool 800 further comprises a radio frequency (RF) power source 834 that is electrically connected to showerhead 810. Radio frequency power source 834 is configured to form a plasma using a gas mixture. For example, radio frequency power source 834 can be operated to form a plasma using a gas mixture comprising one or more carbon-containing film precursors to deposit a carbon film.

[0089] Radio frequency power can be supplied to the showerhead electrode or substrate holder electrode in various examples. As shown in FIG. 8, the radio frequency power is provided to showerhead 810, and substrate support 804 is configured as a grounded opposing electrode. In other examples, radio frequency power source 834 can supply radio frequency power to substrate support 804, and showerhead 810 can be grounded. In the depicted example, a capacitively coupled plasma can be formed in processing chamber 802 between showerhead 810 and substrate support 804. In other examples, an inductively coupled plasma can be used.

[0090] Processing tool 800 further includes a matching network 836 for impedance matching of radio frequency power source 834. Radio frequency power source 834 can be configured to provide radio frequency energy of any suitable frequency and power. Examples frequencies include 400 kHz, 13.56 MHz, 27 MHz, 60 MHz, and 100 MHz. In some examples, radio frequency power source 834 is configured to operate at a plurality of different frequencies and/or powers. For example, as described above, a plasma can comprise a LF component and a HF component. Examples of frequencies for the LF radio frequency energy component can include frequencies of 3 MHz and below. The LF radio frequency energy component can comprise a power of 0 to 3000 W, in some examples. Further, the HF radio frequency energy component can comprise frequencies of 3 MHz to 300 MHz. The HF radio frequency energy component can comprise a power of 50 W to 6500 W, in some examples.

[0091] Processing tool 800 further comprises a controller 850 configured to control operation of the processing tool. The controller 850 is operatively coupled to substrate heater 808, flow control hardware 812, exhaust system 832, and radio frequency power source 834. Controller 850 is configured to control various functions of processing tool 800 to perform substrate processing including deposition phases, etching phases, and controlled etch phases. For example, controller 850 is configured to control processing tool 800 to cause operation of substrate heater 808 to heat a substrate to a desired temperature. Examples include temperatures of 50 °C to 650 °C. Controller 850 also is configured to cause operation of flow control hardware 812 to flow a selected gas or mixture of gases at a selected rate into processing chamber 802. Controller 850 is further configured to cause operation of exhaust system 832 to remove gases from processing chamber 802. Controller 850 is configured to cause operation of radio frequency power source 834 to form a plasma, as well as to control any other suitable functions of processing tool 800.

[0092] Controller 850 can comprise any suitable computing system. FIG. 9 schematically shows a non-limiting example of a computing system 900 that can enact one or more of the methods and processes described above. Computing system 900 is shown in simplified form. Computing system 900 can take the form of one or more personal computers, workstations, computers integrated with substrate processing tools, and/or network accessible server computers.

[0093] Computing system 900 includes a logic subsystem 902 and a storage subsystem 904. Computing system 900 can optionally include a display subsystem 906, input subsystem 908, communication subsystem 910, and/or other components not shown in FIG. 9. Controller 850 is an example of computing system 900.

[0094] Logic subsystem 902 includes one or more physical devices configured to execute instructions. For example, the logic subsystem can 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 can be implemented to perform a task, implement a data type, transform the state of one or more components, achieve a technical effect, or otherwise arrive at a desired result.

[0095] The logic subsystem can include one or more processors configured to execute software instructions. Additionally or alternatively, the logic subsystem can include one or more hardware or firmware logic subsystems configured to execute hardware or firmware instructions. Processors of the logic subsystem can be single-core or multi-core, and the instructions executed thereon can be configured for sequential, parallel, and/or distributed processing. Individual components of the logic subsystem optionally can be distributed among two or more separate devices, which can be remotely located and/or configured for coordinated processing. Aspects of the logic subsystem can be virtualized and executed by remotely accessible, networked computing devices configured in a cloud-computing configuration.

[0096] Storage subsystem 904 includes one or more physical devices configured to hold instructions 912 executable by the logic subsystem to implement the methods and processes described herein. When such methods and processes are implemented, the state of storage subsystem 904 can be transformed — e.g., to hold different data.

[0097] Storage subsystem 904 can include removable and/or built-in devices. Storage subsystem 904 can include optical memory (e.g., CD, DVD, HD-DVD, Blu- Ray Disc, etc.), semiconductor memory (e.g., RAM, EPROM, EEPROM, etc.), and/or magnetic memory (e.g., hard-disk drive, floppy-disk drive, tape drive, MRAM, etc.), among others. Storage subsystem 904 can include volatile, nonvolatile, dynamic, static, read/write, read-only, random-access, sequential-access, location-addressable, file- addressable, and/or content-addressable devices.

[0098] It will be appreciated that storage subsystem 904 includes one or more physical devices. However, aspects of the instructions described herein alternatively can be propagated by a communication medium (e.g., an electromagnetic signal, an optical signal, etc.) that is not held by a physical device for a finite duration.

[0099] Aspects of logic subsystem 902 and storage subsystem 904 can be integrated together into one or more hardware-logic components. Such hardware-logic components can include field-programmable gate arrays (FPGAs), program- and application-specific integrated circuits (PASIC / ASICs), program- and applicationspecific standard products (PSSP / ASSPs), system-on-a-chip (SOC), and complex programmable logic devices (CPLDs), for example. [00100] When included, display subsystem 906 can be used to present a visual representation of data held by storage subsystem 904. This visual representation can take the form of a graphical user interface (GUI). As the herein described methods and processes change the data held by the storage subsystem, and thus transform the state of the storage subsystem, the state of display subsystem 906 can likewise be transformed to visually represent changes in the underlying data. Display subsystem 906 can include one or more display devices utilizing virtually any type of technology. Such display devices can be combined with logic subsystem 902 and/or storage subsystem 904 in a shared enclosure, or such display devices can be peripheral display devices.

[00101] When included, input subsystem 908 can comprise or interface with one or more user-input devices such as a keyboard, mouse, or touch screen. In some examples, the input subsystem can comprise or interface with selected natural user input (NUI) componentry. Such componentry can be integrated or peripheral, and the transduction and/or processing of input actions can be handled on- or off-board. Example NUI componentry can include a microphone for speech and/or voice recognition, and an infrared, color, stereoscopic, and/or depth camera for machine vision and/or gesture recognition.

[00102] When included, communication subsystem 910 can be configured to communicatively couple computing system 900 with one or more other computing devices. Communication subsystem 910 can include wired and/or wireless communication devices compatible with one or more different communication protocols. As non-limiting examples, the communication subsystem can be configured for communication via a wireless telephone network, or a wired or wireless local- or wide-area network. In some examples, the communication subsystem can allow computing system 900 to send and/or receive messages to and/or from other devices via a network such as the Internet.

[00103] It will be understood that the configurations and/or approaches described herein are exemplary in nature, and that these specific examples or examples are not to be considered in a limiting sense, because numerous variations are possible. The specific routines or methods described herein can represent one or more of any number of processing strategies. As such, various acts illustrated and/or described can be performed in the sequence illustrated and/or described, in other sequences, in parallel, or omitted. Likewise, the order of the above-described processes can be changed.

[00104] The subject matter of the present disclosure includes all novel and non- obvious combinations and sub-combinations of the various processes, systems and configurations, and other features, functions, acts, and/or properties disclosed herein, as well as any and all equivalents thereof.

Claims

CLAIMS:

1. On a substrate comprising a feature and a field region adjacent to the feature, a method of etching a carbon film deposited on the field region and within the feature, the method comprising: forming a plasma using a gas mixture comprising an etching agent and a carbon- containing film precursor to generate reactive etching species and reactive deposition species; and etching the carbon film at a higher rate in the field region than within the feature by depositing carbon within the feature during etching.

2. The method of claim 1, wherein the plasma is a second plasma and is formed in a second etching phase, and further comprising performing a first etching phase prior to the second etching phase, the first etching phase comprising forming a first plasma using the etching agent and omitting the carbon-containing film precursor to etch the carbon film in the field region.

3. The method of claim 2, further comprising, in a third etching phase, forming a third plasma using the etching agent and omitting the carbon-containing film precursor to etch the carbon film within the feature.

4. The method of claim 2, wherein the second etching phase comprises etching a thickness of 1 to 20 nm of the carbon film in the field region.

5. The method of claim 1, wherein the plasma is a first plasma, and further comprising forming a second plasma using the carbon-containing film precursor and omitting the etching agent to deposit carbon film into the feature and in the field region.

6. The method of claim 5, further comprising performing a plurality of chemical vapor deposition (CVD) cycles, each CVD cycle of the plurality of CVD cycles comprising: forming the second plasma using the carbon-containing film precursor and omitting the etching agent to deposit the carbon film into the feature and in the field region; and after depositing the carbon film, forming the first plasma using the gas mixture comprising the etching agent and the carbon-containing film precursor to etch the carbon film at a higher rate in the field region than within the feature.

7. The method of claim 1, wherein the gas mixture comprising the etching agent and the carbon-containing film precursor has a molar ratio of the carbon-containing film precursor to the etching agent of 1 :5 to 1 :20.

8. The method of claim 1, wherein the etching agent comprises one or more of hydrogen or ammonia.

9. The method of claim 1, wherein the etching agent comprises one or more of oxygen, carbon dioxide, sulfur dioxide, or nitrous oxide.

10. The method of claim 1, wherein the carbon-containing film precursor comprises one or more of acetylene, ethylene, or propylene.

11. The method of claim 1, wherein the etching the carbon film is performed at a temperature of 500 °C to 650 °C.

12. A processing tool, comprising: a processing chamber; a substrate support disposed within the processing chamber; a radio frequency power source configured to generate a plasma in the processing chamber; flow control hardware configured to flow an etching agent and a carbon- containing film precursor into the processing chamber; and a controller configured to process a substrate comprising a feature and a field region adjacent to the feature, the substrate further comprising a carbon film in the field region and within the feature, the controller configured to cause operation of the flow control hardware to flow the etching agent and the carbon-containing film precursor into the processing chamber, and cause operation of the radio frequency power source to form a plasma in the processing chamber using the etching agent and the carbon-containing film precursor to generate reactive etching species and reactive deposition species in the plasma, and cause etching of the carbon film at a higher rate in the field region than within the feature by depositing carbon within the feature during etching.

13. The processing tool of claim 12, wherein the causing of the etching of the carbon film at a higher rate in the field region than within the feature occurs within a second etching phase, the plasma is a second plasma, and the controller is further configured to, in a first etching phase prior to the second etching phase, cause operation of the flow control hardware to flow the etching agent into the processing chamber, and cause operation of the radio frequency power source to form a first plasma using the etching agent and omitting the carbon-containing film precursor to cause etching of the carbon film in the field region.

14. The processing tool of claim 13, wherein the controller is further configured to, in a third etching phase after the second etching phase, cause operation of the flow control hardware to flow the etching agent into the processing chamber, and cause operation of the radio frequency power source to form a third plasma using the etching agent and omitting the carbon-containing film precursor to cause etching of the carbon film within the feature.

15. The processing tool of claim 12, wherein the causing of the etching of the carbon film at a higher rate in the field region than within the feature occurs within an etching phase, the plasma is a first plasma, and the controller is further configured to, in a deposition phase after the etching phase, cause operation of the flow control hardware to flow the carbon-containing film precursor into the processing chamber, and cause operation of the radio frequency power source to form a second plasma using the carbon-containing film precursor and omitting the etching agent to deposit carbon film into the feature and in the field region.

16. The processing tool of claim 15, wherein the controller is configured to perform a plurality of chemical vapor deposition (CVD) cycles, each CVD cycle of the plurality of CVD cycles comprising the etching phase and the deposition phase.

17. On a substrate comprising a plurality of features and a field region adjacent to the plurality of features, a method of etching a carbon film deposited on the field region and within the plurality of features, the method comprising: in a first etching phase, forming a first plasma omitting a carbon-containing film precursor to etch the carbon film deposited on the field region; in a second etching phase, forming a second plasma using a gas mixture comprising an etching agent and the carbon-containing film precursor to etch the carbon film, and etching the carbon film at a higher rate in the field region than within the plurality of features by depositing carbon within the plurality of features during etching; and in a third etching phase, forming a third plasma omitting the carbon-containing film precursor to etch the carbon film deposited within the plurality of features.

18. The method of claim 17, wherein the second etching phase comprises etching a thickness of 1 to 20 nm of the carbon film in the field region.

19. The method of claim 17, wherein the etching agent comprises one or more of hydrogen, ammonia, oxygen, carbon dioxide, sulfur dioxide, or nitrous oxide.

20. The method of claim 17, wherein the carbon-containing film precursor comprises one or more of acetylene, ethylene, or propylene.