Carbon film deposition with reducing treatment after shaping etch

Abstract

Examples are disclosed that relate to performing a carbon film deposition process that utilizes a cyclic deposition / etch approach without forming a planarization stop layer within the carbon film. One disclosed example provides a method of depositing a carbon film on a substrate disposed in a processing chamber of a processing tool. The method comprises performing a first carbon deposition cycle to deposit a first portion of the carbon film. The method further comprises performing an oxidative etching process to shape the first portion of the carbon film. The method further comprises performing a reducing plasma treatment on the first portion of the carbon film after performing the oxidative etching process. The method further comprises performing a second carbon deposition cycle to deposit a second portion of the carbon film over the first portion of the carbon film.

Description

CARBON FILM DEPOSITION WITH REDUCING TREATMENT AFTERSHAPING ETCHBACKGROUND

[0001] Electronic device fabrication processes can involve many steps of material deposition, patterning, and removal to form integrated circuits on substrates. Various methods can be used to deposit films of materials onto a substrate. As one example, chemical vapor deposition (CVD) can be used to deposit a film by exposing a substrate to a flow of gas phase precursors. The gas phase precursors undergo chemical reactions to form a film on the substrate. Plasma-enhanced CVD (PECVD) utilizes a plasma to provide energy for the chemical conversion of the precursors to the film. PECVD processes can be used to deposit a wide variety of films, including carbon films.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 performing a carbon film deposition process that utilizes a cyclic deposition / etch approach without forming a planarization stop layer within the carbon film. One disclosed example provides a method of depositing a carbon film on a substrate disposed in a processing chamber of a processing tool. The method comprises performing a first carbon deposition cycle to deposit a first portion of the carbon film. The method further comprises performing an oxidative etching process to shape the first portion of the carbon film. The method further comprises performing a reducing plasma treatment on the first portion of the carbon film after performing the oxidative etching process. The method further comprises performing a second carbon deposition cycle to deposit a second portion of the carbon film over the first portion of the carbon film.

[0004] In some such examples, the method further comprises performing a second oxidative etching process to shape the second portion of the carbon film, and performing a second reducing plasma treatment on the second portion of the carbon film after performing the second oxidative etching process.

[0005] Alternatively or additionally, in some such examples, the method further comprises performing a planarization process on the carbon film to remove an overburden of the carbon film from the substrate.

[0006] Alternatively or additionally, in some such examples, performing the reducing plasma treatment comprises forming a plasma with one or more of hydrogen gas, hydrazine, or ammonia.

[0007] Alternatively or additionally, in some such examples, forming a plasma with one or more of hydrogen gas, hydrazine, or ammonia comprises forming an in-situ plasma.

[0008] Alternatively or additionally, in some such examples, performing the oxidative etching process comprises exposing the first portion of the carbon film to a plasma comprising an oxygen-containing species.

[0009] Alternatively or additionally, in some such examples, the oxygencontaining species comprises one or more of oxygen, ozone, carbon dioxide, water vapor, hydrogen peroxide, or nitrous oxide.

[0010] Alternatively or additionally, in some such examples, performing the reducing plasma treatment comprises using a single frequency plasma.

[0011] Alternatively or additionally, in some such examples, performing the reducing plasma treatment comprises using a multi -frequency plasma.

[0012] Another example provides a processing tool, comprising a processing chamber, a substrate holder disposed in the processing chamber, a showerhead positioned within the processing chamber, flow control hardware in fluid communication with the processing chamber, a power source configured to provide power to form a plasma, and a controller. The controller comprises instructions executable to control the processing tool. The instructions comprise instructions executable to cause the processing tool to expose a substrate on the substrate holder to a carbon-containing precursor to deposit a first portion of a carbon film. The controller further comprises instructions executable to cause the processing tool to perform an oxidative etching process to shape the first portion of the carbon film. The controller further comprises instructions executable to cause the processing tool to perform areducing plasma treatment on the first portion of the carbon film after performing the oxidative etching process. The controller further comprises instructions executable to cause the processing tool to expose the substrate to the carbon-containing precursor to deposit a second portion of the carbon film over the first portion of the carbon film.

[0013] In some such examples, the controller further comprises instructions executable to cause the processing tool to perform a second oxidative etching process to shape the second portion of the carbon film, and to perform a second reducing plasma treatment on the second portion of the carbon film after performing the second oxidative etching process.

[0014] Alternatively or additionally, in some such examples, the controller further comprises instructions executable to cause the processing tool to perform the reducing plasma treatment by forming a plasma with one or more of hydrogen gas, hydrazine, or ammonia.

[0015] Alternatively or additionally, in some such examples, the power source is configured to form an in-situ plasma.

[0016] Alternatively or additionally, in some such examples, the instructions executable to cause the processing tool to perform the oxidative etching process comprise instructions executable to cause the processing tool to expose the first portion of the carbon film to a plasma comprising an oxygen-containing species.

[0017] Alternatively or additionally, in some such examples, the instructions executable to cause the processing tool to perform the reducing plasma treatment comprise instructions executable to control the processing tool to form the plasma using a single frequency energy source.

[0018] Another example provides a method of depositing a carbon film on a substrate disposed in a processing chamber of a processing tool. The method comprises performing a plurality of carbon film deposition and etching cycles, wherein one or more deposition and etching cycles of the plurality of deposition and etching cycles comprises performing a carbon deposition cycle to deposit the carbon film, and performing an oxidative etching process to form a first etch / deposition interface, and wherein one or more other deposition and etching cycles of the plurality of deposition and etching cycles comprises performing a carbon deposition cycle to deposit the carbon film, performing an oxidative etching process to shape the carbon film, and performing a reducing plasma treatment on the carbon film after performing the oxidative etching process to form a second etch / deposition interface.

[0019] In some such examples, the method further comprises performing a planarization process on the carbon film to remove an overburden of the carbon film from the substrate, wherein the planarization process removes the second etch / deposition interface but not the first etch / deposition interface.

[0020] Additionally or alternatively, in some such examples, performing the reducing plasma treatment comprises forming a plasma with one or more of hydrogen gas, hydrazine, or ammonia.

[0021] Additionally or alternatively, in some such examples, forming the plasma with one or more of hydrogen gas, hydrazine, or ammonia comprises forming an in-situ plasma.

[0022] Additionally or alternatively, in some such examples, performing the reducing plasma treatment comprises using a remote plasma.BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIGS. 1A-1D schematically show structures formed during an example 3D NAND memory fabrication process.

[0024] FIGS. 2A-2C schematically show the formation of a thin carbon gapfill film due to the carbon film pinching off a gap during deposition.

[0025] FIGS. 3A-3F schematically show structures formed in a carbon gapfill deposition process that can form a planarization stop layer at a deposition / etch interface within the carbon film.

[0026] FIG. 4 shows a flow diagram illustrating an example method of depositing a carbon film by using cyclic deposition / etching steps with a reducing treatment after etching steps.

[0027] FIGS. 5A-5F schematically show example substrate structures formed by an implementation of the methods of FIG. 4.

[0028] FIG. 6 shows a flow diagram illustrating another example method of depositing a carbon film by using cyclic deposition / etching steps with a reducing treatment after some etching steps.

[0029] FIG. 7 shows a schematic depiction of an example processing tool.

[0030] FIG. 8 shows a block diagram of an example computing device.DETAILED DESCRIPTION

[0031] The term “carbon-containing precursor” generally represents any material that can be introduced into a processing chamber in a gas phase to form an amorphous carbon film on a substrate. Examples of carbon-containing precursors include alkanes having a general formula CnH2n+2 where n is an integer in a range of 1 to 10 (such as, methane, ethane, etc.), alkenes having a general formula CnELn where n = 2 to 10 (such as, ethylene, propylene, etc.), and alkynes having a general formula CnH2n-2 where n = 2 to 10 (such as, acetylene, propyne, etc.), that are gas-phase under processing conditions. Other examples of carbon-containing film precursors comprise aromatic hydrocarbons, cyclic aliphatic hydrocarbons, heterocyclic compounds, alkyl amines, and other nitrogen-containing compounds that are gas-phase under processing conditions and that include carbon-containing functional groups.

[0032] The term “chemical vapor deposition” (CVD) generally represents a process in which a solid phase film is formed on a substrate by directing a flow of one or more precursor gases over the substrate surface under processing conditions configured to cause the chemical conversion of the precursor gases to the solid phase 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. The terms “growth”, “deposition”, and variants thereof, also can be used to refer to film formation.

[0033] The term “deposit” and variants thereof generally represents addition of a material to a substrate.

[0034] The term “etch” and variants thereof generally represent removal of a material from a substrate.

[0035] The term "etchant" generally represents a substance used to remove materials from a substrate. Example etchants include hydrogen (Eb), other hydrogencontaining gases (e.g. ammonia (NH3) and hydrazine (N2H4)) halogen-containing gases, and oxygen-containing gases. Example halogen-containing etchants include chlorine (Ch), fluorine (F2), bromine (Bn), iodine (I2), halogen acids (hydrofluoric acid (HF), hydrochloric acid (HC1), hydrobromic acid (HBr), hydroiodic acid (HI)), nitrogen trifluoride (NF3), boron trifluoride (BF3), and sulfur hexafluoride (SFe). Example oxygen-containing etchants include carbon monoxide (CO), carbon dioxide (CO2), carbon oxysulfide (COS), sulfur dioxide (SO2), and molecular oxygen (O2).

[0036] 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, valves, and various conduits, for example. Example chemical sources include film precursor sources, purge gas sources, and reactant gas sources.

[0037] The term “plasma” generally represents an ionized gas comprising gasphase cations and free electrons.

[0038] The term “processing chamber” generally represents an enclosure in which chemical and / or physical processes are performed on substrates. The pressure, temperature, gas flow rate, and atmospheric composition within a processing chamber can be controllable to perform chemical and / or physical processes.

[0039] The term “processing tool” generally represents a machine including a processing chamber and other hardware configured to enable processing to be carried out in the processing chamber.

[0040] The term “showerhead” generally represents a processing chemical outlet comprising a plurality of holes distributed across an area.

[0041] The term “substrate” generally represents any object on which a film can be deposited.

[0042] The term “substrate holder” generally represents any apparatus for holding a substrate in a processing chamber during a process.

[0043] The term “3D NAND” is an abbreviation of three-dimensional NOT AND, and generally represents memory architecture based upon NOT AND logic gates.

[0044] As described above, the fabrication of electronic devices involves many steps of material deposition, patterning, and removal to form integrated circuits, such as logic and / or memory circuits, on substrates. Some steps can involve the deposition of amorphous carbon films to fill gaps in a substrate. A gap is a feature that has a recessed topology compared to adjacent substrate surfaces. An amorphous carbon film, hereinafter referred to as a carbon film, can be used as a gapfill material. Carbon gapfill can be used, for example, to protect sidewalls and / or other surfaces within a feature from damage caused by a subsequent etching process. Carbon films can be deposited using plasma enhanced chemical vapor deposition (PECVD).

[0045] Performing carbon gapfill processes using PECVD can pose various challenges. For example, when performing some carbon gapfill processes, carbon tends to deposit preferentially closer to an opening of the gap compared to deeper within thegap. As a result, the carbon film can form a pinch-off closer to the opening of the gap. The pinch-off restricts further carbon deposition deeper within the gap than the pinch- off. This can result in less carbon being deposited into the gap than desired.

[0046] To avoid incomplete gapfill, a carbon gapfill process can utilize cyclic deposition and etching steps. The deposition steps deposit carbon onto the substrate, including into the gap. The etching steps remove carbon from closer to the opening of the gap, thereby shaping the carbon and helping to prevent the growing carbon film from pinching off the gap and forming a void. This allows a greater amount of carbon to deposit deeper within the gap compared to carbon deposition processes that do not utilize cyclic deposition / etching steps. The deposition steps and etching steps can be repeated cyclically until a desired carbon gapfill film is formed.

[0047] One use of carbon gapfill is in the formation of three-dimensional (3D) integrated circuits, such as 3D NAND memory devices. 3D NAND memory devices are built upon stacked pairs of material layers, with the "active" device layer being one of the materials (e.g. silicon nitride) in the pair and the other being a dielectric (e.g. silicon oxide) for electrical isolation. By stacking these pairs of layers, manufacturers are able to create more active layers per unit substrate area. To form a 3D NAND device, first the stack of pairs of material layers is deposited. This stack can be referred to as a mold stack. Then, high aspect ratio channel holes are etched through the mold stack, and memory cells are formed in the active device layers within the holes.

[0048] As it can be challenging to etch a hole with consistent width through a mold stack having a large number of layers (hundreds in some examples), the mold stack can be formed in stages. As one example of such a process, in each stage, a subset (a “deck”) of pairs of material layers is deposited. Then, the high aspect ratio holes are etched through the deck. Next, a subsequent deck is deposited, and holes are etched through the subsequent deck to align with the holes in the previous deck. FIGS. 1 A-1D illustrate an example of such a process. FIG. 1A shows a substrate 100 comprising a first deck 102. The first deck 102 comprises a plurality of alternating material layers. Further, a gap in the form of a channel hole (“hole 104”) has been etched through the first deck 102. Next, FIG. IB shows carbon deposited on the surface of the first deck 102, and carbon deposited within the hole 104 (“carbon gapfill”). The layer of carbon on the first deck 102 is shown at 112. The carbon gapfill is shown at 114. The carbon can be deposited using plasma enhanced chemical vapor deposition (PECVD), as described below. Continuing, in FIG. 1C, the overburden of the layer of carbon 112 onthe surface of the first deck is removed by planarization, leaving the carbon gapfill 114 within the hole 104. Then, in FIG. ID, a next deck 130 is deposited, and a hole 134 that aligns with the hole 104 in the first deck 102 is etched through the next deck 130.

[0049] The carbon gapfill 114 acts as an etch stop layer that protects the surfaces within the hole 104 from damage during the etching of the hole 134 through the next deck 130. However, if the carbon gapfill 114 is too thin, the process of etching the hole 134 through the next deck can break through the carbon gapfill 114. This can cause damage to surfaces within the hole 104. As carbon tends to preferentially deposit in a gap toward an opening of a gap, there is a risk that a carbon gapfill film may pinch off a gap before forming a sufficiently thick etch stop layer in the gap. This is shown in FIGS 2A-2C. FIGS. 2A and 2B show a substrate 200 with a first deck 201, and a carbon film 202 respectively at a first time and a second time during a carbon film deposition process. As can be seen, the carbon film 202 deposits within a hole 204 preferentially closer to an opening 206 of the hole 204 than deeper within the hole 204. This can lead to the carbon film 202 pinching off the hole 204, as illustrated in FIG. 2B, before forming a sufficiently thick etch stop layer within the hole 204. Referring next to FIG. 2C, after the carbon film overburden is removed by planarization, the carbon film 202 within the hole 204 is relatively thin, and poses a risk of failure when a hole is etched through a next deck of materials deposited over the first deck 201.

[0050] As mentioned above, to avoid this issue, a cycling deposition / etching process can be used to perform a carbon gapfill process. FIGS. 3A-3F illustrate an example cyclic deposition / etching process to perform carbon gapfill. First, FIG. 3A shows a substrate 300 with a first deck 302, and a gap in the form of a hole 304 formed in the first deck. Further, a portion of a carbon film 306 is deposited on a surface of the first deck 302 and partially within the hole 304. The term “portion” is used herein to refer to a part of a carbon film that is deposited in a single deposition cycle of a cyclic deposition / etch process. The term “portion” also refers to the part of carbon film after an etching step has been performed, even though some carbon from the film portion has been removed. Referring next to FIG. 3B, prior to the carbon film 306 pinching off the hole 304, an etching process is performed (e.g. using hydrogen, carbon dioxide, or other suitable carbon etching chemistry) to shape the carbon film 306, thereby widening the opening of the hole 304. The etching process removes more of the carbon film 306 within the hole 304 from locations closer to an opening of the hole 304 than from deeper within the hole 304. FIG. 3C shows the carbon film 306 after a second deposition stepthat deposits a second film portion. FIG. 3D shows the carbon film 306 after a second etching step to further shape the carbon film 306. FIGS. 3C and 3D show a deposit! on / etch interface by dashed line 308. Additional cycles of deposition and etching can be performed as desired. Thus, FIG. 3E shows the carbon film 306 after completing the carbon film deposition process, and illustrates a second deposition / etch interface by dashed line 308 A.

[0051] Compared to the carbon film 202 of FIGS. 2A-2C, the carbon film 306 within the hole 304 has a greater thickness. Thus, the carbon film 306 can be a more robust etch stop layer than the carbon film 202. However, film nonuniformities at deposition / etch interfaces 308 and 308A can lead to issues in later processing steps. For example, the use of an oxidative etching process to perform the etching processes that shape the carbon film 306 can result in planarization stop layers forming at the deposition / etch interfaces 308, 308A. Oxidative etching processes can use an oxygencontaining etchant to form volatile carbon oxides, thereby etching the carbon film. However, the oxidative etching processes can leave behind a surface layer on the carbon film with a different surface charge than that of a carbon film that has not been exposed to an oxidative etching process. Planarization processes (e.g. chemical mechanical planarization (“CMP”)) can utilize a chemically reactive and abrasive slurry to planarize a carbon film by polishing. The rate of carbon removal by CMP can be affected by the surface properties, including surface charge, of the carbon film exposed to the CMP slurry. When a CMP process reaches deposition / etch interface 308A, the carbon removal rate of the CMP process can decrease greatly. As a result, carbon film removal can become difficult and slow at deposition / etch interface 308A, essentially stopping at deposition / etch interface 308A. This is illustrated in FIG. 3F. Incomplete removal of the overburden of the carbon film 306 on first deck 302 can cause issues such as poor adhesion of a next deck formed on first deck 302. This can potentially result in delamination of a next deck from first deck 302 when carbon film 306 is removed in a downstream process step.

[0052] One possible solution to the above planarization-stop issue is to use a reducing etching process, such as a hydrogen-based etching process. In a hydrogenbased etching process, hydrogen radicals formed in a plasma react with carbon in the carbon layer and form volatile hydrocarbons, such as methane. However, the hydrogen radicals can migrate relatively deeply within a deposited carbon film compared to other etchants. This can result in the etching step removing less carbon than desired fromcarbon film regions closer to an opening of a gap, and more carbon than desired being removed from carbon film regions deeper within the gap, compared to other etchants. Therefore, a hydrogen-based etching process may be less effective in shaping a carbon film in a cyclic carbon deposition / etch process than an oxidative etching process.

[0053] Accordingly, examples are disclosed that relate to performing a reducing plasma treatment after performing an oxidative etching process in a cyclic carbon deposition / etch process used to deposit a carbon film. The reducing plasma treatment exposes the surface of a carbon film portion to a reducing species such as hydrogen radicals after an oxidative etch has been performed on the carbon film portion. The reducing plasma treatment can modify the surface charge of the carbon film portion to at least partially recover a planarization rate. Thus, the reducing plasma treatment can, in effect, remove the planarization stop layer that is formed at the etch interface before depositing a next carbon film portion. This can allow the entire carbon film overburden to be removed by planarization prior to depositing a next mold stack deck, thereby helping to prevent the next deck from delaminating when the carbon film is removed in a later processing step.

[0054] FIG. 4 shows a flow diagram illustrating an example method 400 of depositing a carbon film by using cyclic deposition / etching steps with a reducing treatment after etching steps. Method 400 comprises, at 402, performing a carbon deposition cycle to form a portion of a carbon film. As described above, the portion of the carbon film can be deposited using PECVD. Example carbon-containing precursors that can be used for the PECVD deposition of carbon include those listed above. FIG. 5A shows an example portion of a carbon film 506 formed on a deck 502. The deck 502 is formed on a substrate 500. The portion of the carbon film 506 in FIG. 5A is deposited on a surface of the deck 502 and within a gap 504 formed in the deck 502.

[0055] Returning to FIG. 4, method 400 further comprises, at 404, performing an oxidative etching process to shape the portion of the carbon film. The oxidative etching process can comprise exposing the substrate to reactive oxygen-containing species formed in a plasma. Any suitable oxygen-containing gas can be introduced into the plasma. Examples include carbon monoxide (CO), carbon dioxide (CO2), carbon oxysulfide (COS), sulfur dioxide (SO2), and / or molecular oxygen (O2). The reactive oxygen-containing species react with the carbon of the carbon film layer to shape the carbon film layer. FIG. 5B shows the portion of carbon film 506 of FIG. 5 A after an oxidative etching process has been performed to shape the portion of the carbon film506. Any suitable plasma conditions can be used to perform the oxidative etching process. In some examples, a single frequency radiofrequency (RF) plasma can be used. The single frequency plasma can have a frequency within a range of 3 megahertz (MHz) to 300 MHz in some examples. In more particular examples, the single frequency plasma can have a frequency of 13.56 MHz or 27 MHz. In other examples, a multifrequency plasma can be used. In such examples, a plasma can have a relatively lower frequency (LF) RF power component having a frequency with a range of 30 kHz - 2.9 MHz can be used, in addition to a relatively higher frequency (HF) power component with a frequency of between 3 MHz and 300 MHz. The use of a plasma with a LF RF power component in addition to a HF RF power component can cause more ion bombardment of a substrate surface. This can reduce a planarization rate in some examples. Thus, in such examples, the LF RF power component can be omitted.

[0056] As described above, the oxidative etching process can form a surface with surface charge characteristics that can affect a planarization rate of a subsequent CMP process. This can effectively form a planarization stop layer in some examples. As such, method 400 comprises, at 406, performing a reducing plasma treatment on the portion of the carbon film after performing the oxidative etching process. The reducing plasma treatment can comprise forming hydrogen radicals in a plasma. This is depicted schematically in FIG. 5C. The plasma can include any suitable hydrogen-containing gas. Example hydrogen-containing gases include molecular hydrogen (H2), ammonia (NH3), and hydrazine (N2H4). In some examples, the plasma can include one or more other components, such as an inert gas. However, as mentioned above, ion bombardment can reduce a planarization rate in some examples. Thus, in such examples, the plasma may be formed without an inert gas, and under conditions (e.g. relatively lower plasma power levels, a single HF RF frequency, relatively higher processing chamber pressures, etc.) configured to expose the substrate primarily to hydrogen radicals, rather than to ion bombardment. Further, in other examples, another reducing agent than a hydrogen-containing gas can be used in a reducing plasma treatment. Any suitable pressure can be maintained in a processing chamber during the reducing plasma treatment. Example pressures include pressures within a range of 1 - 20 millitorr (mTorr). In other examples, processing chamber pressures outside of this range can be used.

[0057] Continuing with FIG. 4, after shaping the carbon film at 404 and performing the reducing plasma treatment at 406, another carbon film deposition cycleis performed at 407 to form another carbon film portion. If additional shaping will be performed at 408, then method 400 returns to step 404, and again performs steps 404, 406, and 407. FIG. 5D shows the carbon film 506 after performing an additional deposition / etch cycle, and during performing of another reducing plasma treatment. A deposition / etch interface from the prior deposit! on / etch / treatment cycle is shown at 508.

[0058] On the other hand, if additional shaping is not performed, then the most recently deposited carbon film portion is not shaped. FIG. 5E shows carbon film 506 after the deposition process is complete. In additional deposition / etch / treatment interface 508, a second deposition / etch / treatment interface is shown at 508A.

[0059] Method 400 then proceeds to step 410, where a planarization process is performed to remove the overburden of the carbon film from the surface of the deck. FIG. 5F shows the carbon 506 after performing a planarization process. The reducing plasma treatments used to treat deposition / etch / treatment interfaces 508 and 508A can help avoid these interfaces from acting as planarization stop layers. It has been found that a planarization rate of a planarization process used to planarize a carbon deposited according to method 400 can be approximately 80% of the planarization rate of a carbon film deposited without using a cyclic deposition / etching process. In contrast, a planarization rate of a carbon film deposited using a cyclic deposition / etching process without a reducing plasma treatment performed after an oxidative etching process can be effectively zero. In these experiments, a water contact angle of a water droplet on the carbon film changed from approximately ten degrees prior to the reducing plasma treatment to approximately fourteen degrees after the reducing plasma treatment, illustrating the change in surface charge achieved by the reducing plasma treatment. Therefore, the example method of FIG. 4 can produce a carbon gapfill film with a sufficient thickness to act as an effective etch stop layer for etching a channel hole of a subsequent deck in a 3D NAND process, and without having a deposition / etch interface that act as a planarization stop.

[0060] In the example of FIG. 4, a reducing plasma treatment is performed after each oxidative etch step. However, some deposition / etching interfaces may be located fully within a gap, and thus not be exposed during a subsequent planarization process. In such examples, a reducing plasma treatment can be omitted for any deposition / etch interfaces that will not be exposed by a planarization process.

[0061] FIG. 6 shows another example method 600 for depositing a carbon film. Method 600 comprises, at 602, performing a carbon deposition cycle to form a portionof a carbon film. As described above, the portion of the carbon film can be deposited using PECVD. Example carbon-containing precursors that can be used for the PECVD deposition of carbon include those listed above. Method 600 further comprises performing an oxidative etching process to shape the first portion of the carbon film, at 604. Next, as indicated at 606, if the deposition / etching interface formed by the oxidative etching process at 604 will be exposed during a subsequent planarization process, then method 600 comprises, at 608, performing a reducing plasma treatment on the portion of the carbon film after performing the oxidative etching process, followed by performing another carbon deposition cycle at 609. On the other hand, if the deposition / etching interface formed by the oxidative etching process at 604 will not be exposed by a subsequent planarization process, then method 600 comprises not performing the reducing plasma treatment on the portion of the carbon film after the oxidative etching process, and proceeding to step 609 to perform the next carbon deposition cycle.After performing another carbon deposition cycle at 609, it is determined at 610 whether shaping is needed. If additional shaping is needed, then method 600 returns to 604 to perform another oxidative etching process. On the other hand, if additional shaping is not needed, then method 600 proceeds to performing a planarization process to remove the overburden of carbon film, as shown at 612. As described above, by performing the reducing plasma treatment after oxidative etching for deposit! on / etch / treatment interfaces that will be exposed during a subsequent planarization process, the formation of a planarization stop layer within the carbon film can be avoided.

[0062] FIG. 7 shows a schematic depiction of a processing tool 700 configured for performing plasma-enhanced chemical vapor deposition (PECVD). Processing tool 700 comprises a processing chamber 702 and a substrate holder 704 within the processing chamber. The substrate holder 704 is configured to support a substrate 706 disposed within processing chamber 702. The substrate holder 704 comprises a substrate heater 708. In other examples, a heater can be omitted, or can be located elsewhere within processing chamber 702. The processing tool 700 further comprises a showerhead 710 for introducing processing chemicals into the processing chamber. In some examples, the processing tool 700 comprises a heater configured to heat showerhead 710.

[0063] The processing tool 700 further comprises an optional secondary purge gas outlet 711. Secondary purge gas outlet 711 is configured to form secondary purge gas flow around the outside edge of showerhead 710.

[0064] The processing tool 700 further comprises flow control hardware 712. The flow control hardware 712 connects processing chemical source(s) to the processing chamber. In the depicted example, the flow control hardware 712 connects a carbon-containing precursor source 716, an oxidative etchant source 718, an inert gas source 722, and a hydrogen-containing gas source 723 to the processing chamber. The flow control hardware 712 can include any suitable components. For example, the flow control hardware 712 can comprise one or more valves controllable to place a selected gas source or selected gas sources in fluid connection with showerhead 710. The flow control hardware 712 also can comprise one or more mass flow controllers or other controllers for controlling a flow rate of gas.

[0065] The carbon-containing precursor source 716 comprises any suitable precursor compound(s) for forming a carbon film. Examples of carbon-containing precursors include alkanes having a general formula CnH2n+2 where n is an integer in a range of 1 to 10 (such as, methane, ethane, etc.), alkenes having a general formula CnEEn where n = 2 to 10 (such as, ethylene, propylene, etc.), and alkynes having a general formula CnH2n-2 where n = 2 to 10 (such as, acetylene, propyne, etc.), that are gas-phase under processing conditions. Other examples of carbon-containing film precursors comprise cyclic aliphatic hydrocarbons, aromatic hydrocarbons, heterocyclic compounds, and alkyl amines.

[0066] The oxidative etchant source 718 can comprise any suitable substance or substances that can etch an amorphous carbon film during film deposition. Examples include carbon monoxide (CO), carbon dioxide (CO2), carbon oxysulfide (COS), sulfur dioxide (SO2), water vapor (H2O), hydrogen peroxide (H2O2), and molecular oxygen (O2).

[0067] The inert gas source 722 comprises any suitable inert gas. Examples include argon, helium, neon, krypton, and xenon, as well as nitrogen in some processing environments.

[0068] The hydrogen-containing gas source 723 can comprise any suitable hydrogen-containing gas that can form reactive hydrogen radicals in a plasma to perform a reducing plasma treatment on a carbon film after an oxidative etchingprocess. Example hydrogen-containing gases include molecular hydrogen (H2), ammonia (NH3), and hydrazine (N2H4).

[0069] The processing tool 700 further comprises an exhaust system 732. The exhaust system 732 is configured to exhaust gases from the processing chamber 702. The exhaust system 732 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 712 and exhaust system 732 can be operated to achieve a selected pressure in processing chamber 702 during substrate processing. Further, exhaust system 732 can be operated to purge processing chamber 702.

[0070] The processing tool 700 further comprises an RF power source 734 configured to form an in-situ plasma in processing chamber 702 using a gas mixture. The RF power source 734 can supply RF power to the showerhead electrode or substrate holder electrode in various examples. As shown in FIG. 7, RF power is provided to substrate holder 704, and showerhead 710 is configured as a grounded opposing electrode. In other examples, the RF power source 734 can supply RF power to showerhead 710, and substrate holder 704 can be grounded. In the depicted example, a capacitively coupled plasma can be formed in processing chamber 702 between showerhead 710 and substrate holder 704. In other examples, an inductively coupled plasma can be used. Further, in some examples, a processing tool can be configured to form a remote plasma at a location remote from a processing station, instead of or in addition to an in-situ plasma. The processing tool 700 further includes a matching network 736 for impedance matching of the RF power source 734.

[0071] In some examples, the radiofrequency power source 734 is configured to provide RF power comprising a lower-frequency (LF) RF power 734A and a higher- frequency (HF) RF power 734B to form a multi-frequency plasma. Example frequencies for the lower-frequency RF power include frequencies of 40 kHz to 3 MHz. Examples frequencies for the higher-frequency RF power include frequencies of 3 MHz to 300 MHz. In other examples, the radiofrequency power source 734 is configured to supply a single frequency (e.g. HF) of RF power.

[0072] The processing tool 700 further comprises a controller 750 configured to control operation of the processing tool. The controller 750 is operatively coupled to the substrate heater 708, the flow control hardware 712, the exhaust system 732, andthe RF power source 734. The controller 750 is configured to control various functions of processing tool 700 to perform PECVD.

[0073] Controller 750 can comprise any suitable computing system. FIG. 8 schematically shows a non-limiting example of a computing system 800 that can enact one or more of the methods and processes described above. Computing system 800 is shown in simplified form. Computing system 800 can take the form of one or more personal computers, workstations, computers integrated with substrate processing tools, and / or network accessible server computers.

[0074] Computing system 800 includes a logic subsystem 802 and a storage subsystem 804. Computing system 800 can optionally include a display subsystem 806, input subsystem 808, communication subsystem 810, and / or other components not shown in FIG. 8. The controller 750 is an example of computing system 800.

[0075] Logic subsystem 802 includes one or more physical devices configured to execute instructions. For example, the logic subsystem 802 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.

[0076] The logic subsystem 802 can include one or more processors configured to execute software instructions. Additionally or alternatively, the logic subsystem 802 can include one or more hardware or firmware logic machines configured to execute hardware or firmware instructions. Processors of the logic subsystem 802 can be singlecore or multi-core, and the instructions executed thereon can be configured for sequential, parallel, and / or distributed processing. Individual components of the logic subsystem 802 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 802 can be virtualized and executed by remotely accessible, networked computing devices configured in a cloud-computing configuration.

[0077] Storage subsystem 804 includes one or more physical devices configured to hold instructions 812 executable by the logic machine to implement the methods and processes described herein. When such methods and processes are implemented, the state of storage subsystem 804 can be transformed — e.g., to hold different data.

[0078] Storage subsystem 804 can include removable and / or built-in devices. Storage subsystem 804 can include optical memory, semiconductor memory, and / or magnetic memory, among others. Storage subsystem 804 can include volatile, nonvolatile, dynamic, static, read / write, read-only, random-access, sequential-access, location-addressable, file-addressable, and / or content-addressable devices.

[0079] It will be appreciated that storage subsystem 804 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.

[0080] Aspects of logic subsystem 802 and storage subsystem 804 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.

[0081] When included, display subsystem 806 can be used to present a visual representation of data held by storage subsystem 804. 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 machine, and thus transform the state of the storage machine, the state of display subsystem 806 can likewise be transformed to visually represent changes in the underlying data. Display subsystem 806 can include one or more display devices utilizing virtually any type of technology. Such display devices can be combined with logic subsystem 802 and / or storage subsystem 804 in a shared enclosure, or such display devices can be peripheral display devices.

[0082] When included, input subsystem 808 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.

[0083] When included, communication subsystem 810 can be configured to communicatively couple computing system 800 with one or more other computingdevices. Communication subsystem 810 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 800 to send and / or receive messages to and / or from other devices via a network such as the Internet.

[0084] 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.

[0085] 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. A method of depositing a carbon film on a substrate disposed in a processing chamber of a processing tool, the method comprising: performing a first carbon deposition cycle to deposit a first portion of the carbon film; performing an oxidative etching process to shape the first portion of the carbon film; performing a reducing plasma treatment on the first portion of the carbon film after performing the oxidative etching process; and performing a second carbon deposition cycle to deposit a second portion of the carbon film over the first portion of the carbon film.

2. The method of claim 1, further comprising performing a second oxidative etching process to shape the second portion of the carbon film, and performing a second reducing plasma treatment on the second portion of the carbon film after performing the second oxidative etching process.

3. The method of claim 1, further comprising performing a planarization process on the carbon film to remove an overburden of the carbon film from the substrate.

4. The method of claim 1, wherein performing the reducing plasma treatment comprises forming a plasma with one or more of hydrogen gas, hydrazine, or ammonia.

5. The method of claim 4, wherein forming the plasma with one or more of hydrogen gas, hydrazine, or ammonia comprises forming an in-situ plasma.

6. The method of claim 1, wherein performing the oxidative etching process comprises exposing the first portion of the carbon film to a plasma comprising an oxygen-containing species.

7. The method of claim 6 wherein the oxygen-containing species comprises one or more of oxygen, ozone, carbon dioxide, water vapor, hydrogen peroxide, or nitrous oxide.

8. The method of claim 1, wherein performing the reducing plasma treatment comprises using a single frequency plasma.

9. The method of claim 1, wherein performing the reducing plasma treatment comprises using a multi-frequency plasma.

10. A processing tool, comprising: a processing chamber; a substrate holder disposed in the processing chamber; a showerhead positioned within the processing chamber; flow control hardware in fluid communication with the processing chamber; a power source configured to provide power to form a plasma; and a controller comprising instructions executable by the controller to control the processing tool, the instructions comprising: instructions executable to cause the processing tool to expose a substrate on the substrate holder to a carbon-containing precursor to deposit a first portion of a carbon film; instructions executable to cause the processing tool to perform an oxidative etching process to shape the first portion of the carbon film; instructions executable to cause the processing tool to perform a reducing plasma treatment on the first portion of the carbon film after performing the oxidative etching process; and instructions executable to cause the processing tool to expose the substrate to the carbon-containing precursor to deposit a second portion of the carbon film over the first portion of the carbon film.

11. The processing tool of claim 10, wherein the controller further comprises instructions executable to cause the processing tool to perform a second oxidative etching process to shape the second portion of the carbon film, and to perform a second reducing plasma treatment on the second portion of the carbon film after performing the second oxidative etching process.

12. The processing tool of claim 10, wherein the controller further comprises instructions executable to cause the processing tool to perform the reducing plasmatreatment by forming a plasma with one or more of hydrogen gas, hydrazine, or ammonia.

13. The processing tool of claim 12, wherein the power source is configured to supply power to form an in-situ plasma.

14. The processing tool of claim 10, wherein the instructions executable to cause the processing tool to perform the oxidative etching process comprise instructions executable to cause the processing tool to expose the first portion of the carbon film to a plasma comprising an oxygen-containing species.

15. The processing tool of claim 10, wherein the instructions executable to cause the processing tool to perform the reducing plasma treatment comprise instructions executable to control the processing tool to form the plasma using a single frequency energy source.

16. A method of depositing a carbon film on a substrate disposed in a processing chamber of a processing tool, the method comprising: performing a plurality of carbon film deposition and etching cycles, wherein one or more deposition and etching cycles of the plurality of deposition and etching cycles comprises performing a carbon deposition cycle to deposit the carbon film, and performing an oxidative etching process to shape the carbon film to form a first etch / deposition interface, and wherein one or more other deposition and etching cycles of the plurality of deposition and etching cycles comprises performing a carbon deposition cycle to deposit the carbon film, performing an oxidative etching process to shape the carbon film, and performing a reducing plasma treatment on the carbon film after performing the oxidative etching process to form a second etch / deposition interface.

17. The method of claim 16, further comprising performing a planarization process on the carbon film to remove an overburden of the carbon film from the substrate, wherein the planarization process removes the second etch / deposition interface but not the first etch / deposition interface.

18. The method of claim 16, wherein performing the reducing plasma treatment comprises forming a plasma with one or more of hydrogen gas, hydrazine, or ammonia.

19. The method of claim 18, wherein forming the plasma with one or more of hydrogen gas, hydrazine, or ammonia comprises forming an in-situ plasma.

20. The method of claim 16, wherein performing the reducing plasma treatment comprises using a remote plasma.

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