Topographically selective ETCH with halogenated carbon

Abstract

Examples are disclosed that relate to shaping a feature using a topologically selective deposition and selective etch. One example provides a method for shaping a film of a gapfill material on a feature of a substrate, the method comprising performing a topologically selective deposition of a carbon film on a portion of the gapfill material of the substrate. The method further comprising forming a plasma using a halogen-containing etchant to incorporate halogen species from the halogen-containing etchant into the carbon film to form a halogenated carbon film. The method further comprising ashing the carbon film to thereby cause etching of the gapfill material by the halogen species selectively at locations that were covered by the halogenated carbon film.

Description

Docket No. LRC24313PPCTTOPOGRAPHICALLY SELECTIVE ETCH WITH HALOGENATED CARBONBACKGROUND

[0001] Semiconductor device fabrication processes involve many steps of material deposition, patterning and removal to form integrated circuits on substrates. Example deposition processes include chemical vapor deposition (CVD) and atomic layer deposition (ALD). CVD involves exposing a substrate in a processing chamber to a flow of one or more precursor compounds under conditions configured to convert the precursor compounds into a film on the substrate. ALD involves depositing a film in a layer-by-layer manner by cyclically adsorbing a film precursor to the substrate, and then chemically converting the adsorbed substrate to a layer of the film.

[0002] Etching processes are used to remove material from substrates. Example etching processes include dry etching processes and wet etching processes. Dry etching methods utilize gas-phase etchants to react with etchable materials to form volatile products. Dry etching methods can be performed by using a plasma to form reactive ions, or by using a thermally driven etching process.SUMMARY

[0003] 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.

[0004] Examples are disclosed that relate to shaping a feature using a topologically selective deposition and selective etch. One example provides a method for shaping a film of a gapfill material on a feature of a substrate, the method comprising performing a topologically selective deposition of a carbon film on a portion of the gapfill material. The method further comprising forming a plasma using a halogencontaining etchant to incorporate halogen species from the halogen-containing etchant into the carbon film to form a halogenated carbon film. The method further comprisingDocket No. LRC24313PPCT ashing the carbon film to thereby cause etching of the gapfill material by the halogen species selectively at locations that were covered by the halogenated carbon film.

[0005] In some such examples, ashing the carbon film to cause etching of the gapfill material comprises forming a tapered profile within the feature.

[0006] Additionally or alternatively, in some such examples, the method further comprises, after ashing the carbon film, densifying the gapfill material by exposing the gapfill material to an ion flux.

[0007] Additionally or alternatively, in some such examples, the method further comprises, prior to performing the topologically selective deposition of the carbon film on the portion of the gapfill material, depositing the gapfill material on the substrate to form a reentrant profile within the feature, and wherein etching the gapfill material etches the reentrant profile of the feature.

[0008] Additionally or alternatively, in some such examples, the method further comprises, after ashing the carbon film, depositing an additional layer of the gapfill material on the substrate and within the feature of the substrate, and cyclically repeating the topologically selective deposition of the carbon film, the forming of the plasma to incorporate the halogen species into the carbon film, the ashing of the carbon film, and the depositing of the additional layer of the gapfill material to fill the feature.

[0009] Additionally or alternatively, in some such examples, the topologically selective deposition of the carbon film on the portion of the gapfill material comprises depositing the carbon film using an ion-driven deposition process.

[0010] Additionally or alternatively, in some such examples, performing the topologically selective deposition of the carbon film on the portion of the gapfill material comprises forming a plasma using a hydrocarbon.

[0011] Additionally or alternatively, in some such examples, the plasma is formed using hydrogen fluoride, fluorine, nitrogen trifluoride, sulfur tetrafluoride, sulfur hexafluoride, xenon difluoride, hydrogen chloride, chlorine, and combinations thereof.

[0012] Additionally or alternatively, in some such examples, ashing the carbon film comprises forming a plasma using oxygen (O2), hydrogen (H2), nitrous oxide (N2O), ozone (O3), and combinations thereof.

[0013] Additionally or alternatively, in some such examples, the gapfill material comprises silicon, silicon oxide, silicon nitride, silicon oxynitride, siliconDocket No. LRC24313PPCT oxycarbide, molybdenum, tungsten, germanium, titanium, titanium nitride, tantalum, and combinations thereof.

[0014] Additionally or alternatively, in some such examples, forming the plasma using the halogen-containing etchant comprises incorporating a first concentration of the halogen species into a first location of the carbon film, and incorporating a second concentration of the halogen species into a second location of the carbon film, the first concentration being greater than the second concentration and the first location being closer to an opening of the recessed feature than the second location.

[0015] Another example provides a method of depositing a film of gapfill material in a recessed feature of a substrate. The method comprises (a) depositing a layer of gapfill material on the substrate and within the recessed feature of the substrate. The method further comprises (b) performing a topologically selective deposition of a carbon film on a portion of the gapfill material. The method further comprises (c) forming a plasma using a halogen-containing etchant to incorporate halogen species from the halogen-containing etchant into the carbon film. The method further comprises (d) ashing the carbon film to thereby cause etching of the gapfill material by the halogen species selectively at locations that were covered by the carbon film. The method further comprises (e) cyclically repeating (b), (c), and (d) for one or more process cycles to shape the layer of gapfill material within the recessed feature.

[0016] In some such examples, forming the plasma using the halogencontaining etchant comprises incorporating a first concentration of the halogen species into a first location of the carbon film near the opening of the recessed feature, and incorporating a second concentration of the halogen species into a second location of the carbon film near the bottom of the recessed feature, the first concentration being greater than the second concentration and the first location being closer to an opening of the recessed feature than the second location.

[0017] Additionally or alternatively, in some such examples, forming the plasma using the halogen-containing etchant comprises incorporating one of fluorine species or chlorine species into the carbon film.

[0018] Additionally or alternatively, in some such examples, the method further comprises cyclically repeating (a), (b), (c), and (d) for one or more process cycles to at least partially fill the recessed feature.Docket No. LRC24313PPCT

[0019] Additionally or alternatively, in some such examples, performing the topologically selective deposition of the carbon film comprises depositing the carbon film using an ion-driven deposition process comprising forming a plasma using argon and a hydrocarbon and a processing pressure within a range of 0.5 Torr to 20 Torr.

[0020] Another example provides a processing tool. The processing tool comprises a processing chamber, a substrate support disposed in the processing chamber, and a substrate heater configured to heat a substrate positioned on the substrate support. The processing tool further comprises a power source configured to form a plasma in the processing chamber. The processing tool further comprises a showerhead configured to introduce processing chemicals into the processing chamber. The processing tool further comprises flow control hardware configured to deliver processing chemicals to the showerhead. The processing tool further comprises a controller configured to control the processing tool to cause the processing tool to deposit a carbon film on a portion of a gapfill material of a substrate by a topologically selective deposition process. The controller is further configured to cause the processing tool to form a plasma using a halogen-containing etchant to incorporate halogen species from the halogen-containing etchant into the carbon film. The controller is further configured to cause the processing tool to ash the carbon film to thereby cause etching of the gapfill material by the halogen species selectively at locations that were covered by the carbon film.

[0021] In some such examples, the controller is further configured to cause the processing tool to deposit the layer of gapfill material on the substrate and within the feature of the substrate.

[0022] Additionally or alternatively, in some such examples, the controller is configured to cause the processing tool to form the plasma using the halogen-containing etchant under processing conditions configured to incorporate a first concentration of the halogen species into upper portions of the carbon film near the opening of the recessed feature, and incorporate a second concentration of the halogen species into lower portions of the carbon film near the bottom of the recessed feature, the first concentration being greater than the second concentration.

[0023] Additionally or alternatively, in some such examples, the gapfill material comprises silicon, silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbide, molybdenum, tungsten, germanium, titanium, titanium nitide, tantalum, or combinations thereof, and wherein forming the plasma using the halogen-containingDocket No. LRC24313PPCT etchant comprises forming the plasma using hydrogen fluoride, fluorine, nitrogen trifluoride, sulfur tetrafluoride, sulfur hexafluoride, xenon difluoride, hydrogen chloride, chlorine, and combinations thereof.BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIGS. 1A-1D schematically show structures formed in an atomic layer deposition (ALD) process to fill a feature that results in seam formation, and subsequent seam deterioration in a subsequent etch step.

[0025] FIGS. 2A-2C schematically show structures formed in an ALD process to fill a reentrant feature that results in a void.

[0026] FIG. 3 shows a flow diagram for an example method for shaping a feature by selectively depositing a carbon film, halogenating the carbon film, and selectively etching material covered by the halogenated carbon film.

[0027] FIGS. 4A-4K schematically show structures formed using the method of FIG. 3 to taper a film deposited in a feature.

[0028] FIGS. 5A-5H schematically show structures formed using the method of FIG. 3 to shape a reentrant feature.

[0029] FIG. 6 schematically shows an example processing tool that can be used to perform a topographically selective deposition and a selective etch.

[0030] FIG. 7 schematically shows an example computing system.DETAILED DESCRIPTION

[0031] The term “ashing” generally represents a dry etch of a carbon film that uses an oxidant such as oxygen (O2), ozone (O3), or nitrous oxide (N2O), to form one or more volatile carbon oxides, or a reducing agent such as hydrogen (H2) to form one or more volatile hydrocarbons. Ashing can utilize a plasma in some examples.

[0032] The term “aspect ratio” generally represents a ratio between a depth of a feature, such as a hole, and an average width of the feature.

[0033] The term “atomic layer deposition” (ALD) generally represents a process in which a film is formed on a substrate in one or more individual layers by sequentially adsorbing a precursor to the substrate and reacting the adsorbed precursor to form a film layer in self-limiting steps. Plasma-enhanced ALD (PEALD) utilizes a plasma of a reactive gas to facilitate a chemical conversion of a precursor adsorbed toDocket No. LRC24313PPCT a substrate to a film on the substrate. Thermal ALD (TALD) utilizes thermal energy to facilitate film formation. The terms “growth”, “deposition”, and variants thereof, also can be used to refer to film formation.

[0034] The term “carbon-containing precursor” generally represents any material that can be introduced into a processing chamber in a gas phase to form a carbon-containing film, such as an amorphous carbon film, on a substrate. Examples of carbon-containing precursors include carbon monoxide (CO), alkanes, alkenes, alkynes, cyclic hydrocarbons, aromatics, alcohols, diols, aldehydes, esters, ethers, ketones, alkyl amines, alkyl diamines, and organosilicon compounds. Examples of alkanes (CnH2n+2 in which n = 1 to 10) include methane, ethane, propane, and butane. Examples of alkenes (CnEkn in which n = 2 to 10, for an alkene with a single carboncarbon double bond) include ethene, propene, and butene. Examples of alkynes (CnEhn- 2 in which n = 2 to 10, for an alkyne with a single carbon-carbon triple bond) include acetylene, propyne, and butyne. Examples of cyclic hydrocarbons include cyclobutane, cyclopentane, and cyclohexane. Examples of aromatics include benzene, toluene, pyridine, and pyrimidine. Examples of alcohols include methanol, ethanol, and propanol. Examples of diols include ethylene glycol, propylene glycol, and hydroquinone. Examples of aldehydes include formaldehyde and acetaldehyde. Examples of esters may include ethyl formate, methyl acetate, and ethyl acetate. Examples of ethers include diethyl ether, methyl phenyl ether, and aromatic ethers such as furan. Examples of ketones include acetone and methyl ethyl ketone. Examples of alkyl halides include ethyl fluoride, isopropyl bromide, and t-butyl chloride. Examples of alkyl amines include methylamine, dimethylamine, trimethylamine, and piperidine. Examples of alkyl diamines include ethylenediamine and 1,3 -diaminopropane.

[0035] 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. Plasma- enhanced chemical-vapor deposition (PECVD) utilizes a plasma to facilitate film formation on a substrate. Thermal CVD (TCVD) utilizes thermal energy in the absence of a plasma to facilitate film formation on a substrate.

[0036] The term “critical dimension” generally represents a width of a feature of a substrate, such as a diameter of a hole formed in a substrate.Docket No. LRC24313PPCT

[0037] The term “etch” and variants thereof generally represent a process in which material is removed from a substrate. The term “selective etch” generally represents a process in which a first material exposed to an etching chemistry is removed from the substrate at a higher rate than a second material exposed to the etching chemistry. An etch using gas phase etchants is referred to as a "dry etch". An etch utilizing liquid phase etchants is referred to as a "wet etch".

[0038] The term “etch rate” generally represents a depth of an etch as a function of time.

[0039] The term “etchant” generally represents a chemical used in an etching process to chemically remove and / or facilitate chemical removal of material from a substrate. The term “etchant gas mixture” generally represents a mixture of one or more gases comprising at least one etchant. Examples of etchants include halogen-containing etchants, such as fluorine-containing etchants and chlorine-containing etchants. Examples of fluorine-containing etchants include fluorine (F2), hydrogen fluoride (HF), sulfur tetrafluoride (SF4), sulfur hexafluoride (SFe), nitrogen trifluoride (NF3), boron trifluoride (BF3), silicon tetrafluoride (SiF4), phosphorus trifluoride (PF3), phosphorus pentafluoride (PFs), tungsten hexafluoride (WFe), molybdenum hexafluoride (MoFe), fluorocarbons (CxFy), and hydrofluorocarbons ((CxHyFz). Examples of chlorine- containing etchants include chlorine (Ch) and hydrogen chloride (HC1).

[0040] The term “feature” generally represents substrate topology. For example, a feature can be a recessed feature that extends into a substrate, or a protrusion that extends out from a surface of a substrate.

[0041] The term “field regions” generally represents surfaces of a substrate oriented generally parallel to a surface plane of a substrate.

[0042] 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.

[0043] The term “plasma” generally represents a gas comprising cations and free electrons.

[0044] The term “precursor” generally represents a substance that can be reacted on a substrate to form a film.

[0045] The term “silicon-containing precursor” generally represents any material that can be introduced into a processing chamber in a gas phase to form aDocket No. LRC24313PPCT silicon-containing film, such as a silicon oxide film, on the substrate. Example silicon- containing precursors for forming silicon oxide films can comprise materials having the general structure:where Ri, R2 and R3 can be the same or different substituents, and can include silanes, siloxy groups, amines, halides, hydrogen, or organic groups, such as alkylamines, alkoxy, alkyl, alkenyl, alkynyl and aromatic groups.

[0046] Example silicon-containing precursors include silanes (SinH2n+2 where n >1), such as silane, disilane, trisilane, and tetrasilane.

[0047] In some examples, a halogen-containing silane (halosilane) can be used such that the silane includes at least one hydrogen atom. Such a silane may have a chemical formula of SiXaHy where X is a halogen, y = 1-3, and a+y = 4. For example, dichlorosilane (EhSiCh) may be used in some examples.

[0048] In some examples, the silicon-containing precursor is an alkoxysilane. Alkoxysilanes that may be used include the following:Hx-Si-(OR)y, where x = 1-3, x+y = 4 and each R is a substituted or unsubstituted alkyl, alkenyl, alkynyl or aromatic group; andHx(RO)y,-Si-Si-(OR)yHx, where each R is a substituted or unsubstituted alkyl, alkenyl, alkynyl or aromatic group.

[0049] In some examples, the silicon-containing precursor may be a siloxane. Example siloxanes include octamethylcyclotetrasiloxane (OMCTS), octamethoxydodecasiloxane (OMODDS), tetramethylcyclotetrasiloxane (TMCTS), triethoxysiloxane (TRIES), and tetraoxymethylcyclotetrasiloxane (TOMCTS).

[0050] In some examples, the silicon-containing precursor can be an aminosilane, such as bis(diethylamino)silane, di(isopropylamino)silane (DIPAS), bis(t- butylamino) silane (BTBAS), (di-sec-butylamino)silane, andtris(dimethylamino)silane (3DMAS). Example aminosilane precursors can include substances having the general formula Hx-Si-(NR)y, where x = 1-3, x+y = 4, and R is a substituted or unsubstituted alkyl, alkenyl, alkynyl or aromatic group or hydride group.Docket No. LRC24313PPCT

[0051] In some examples, the silicon-containing precursor can be an organosilicon compound, such as alkylsilanes and siloxanes.

[0052] More particular examples of silicon-containing precursors include methylsilane, dimethylsilane, trimethylsilane (3MS), ethylsilane, butasilanes, pentasilanes, octasilanes, heptasilane, hexasilane, cyclobutasilane, cycloheptasilane, cyclohexasilane, cyclooctasilane, cyclopentasilane, 1, 4-dioxa-2, 3,5,6- tetrasilacyclohexane, tetraethyl orthosilicate (TEOS), tetramethoxysilane (TMOS), dimethyldiethoxysilane, diethoxymethylsilane (DEMS), diethoxysilane (DES), dimethoxymethylsilane, dimethoxysilane (DMOS), methyl-diethoxysilane (MDES), methyl-dimethoxysilane (MDMS), t-butoxydisilane, triethoxysilane (TES), and trimethoxysilane (TMS or TriMOS).

[0053] An example nitrogen-containing precursor for providing nitrogen for formation of a silicon oxynitride film is N2O.

[0054] Example germanium-containing precursors for forming germanium containing films include germanium tetrachloride (GeCh) and germanium tetrai sopropoxi de .

[0055] Examples of molybdenum-containing precursors for forming molybdenum containing films include bis(tert-butylimino)bis(dimethylamino) molybdenum (C12H30M0N4), molybdenum pentachloride (M0CI5), molybdenum dioxide dichloride (MOO2CI2), molybdenum oxytetrachloride (MoOCh), and molybdenum hexacarbonyl (Mo(CO)e).

[0056] Example tantalum-containing precursors for forming tantalum containing films include tantalum chloride (Tads) and tantalum alkyloxides (e.g., tantalum(V) ethoxide, Ta2(OC2Hs)io).

[0057] Example titanium-containing precursors for forming titanium containing films include titanium tetrachloride (TiCh), titanium tetraisopropoxide (TTIP), and tetrakis-dimethyl-amido titanium (TDMAT).

[0058] Example tungsten-containing precursors for forming tungsten containing films include tungsten hexachloride (WCk), tungsten hexachloride (WCk), bis(tert-butylimino)bis(dimethylamino) tungsten (C12H30N4W), and tungsten hexacarbonyl (W(CO)e).

[0059] The term “selective etch cycle” generally represents a multi-step process that can be repeated to shape a film of gapfill material in a feature. A selective etchDocket No. LRC24313PPCT cycle can comprise a selective deposition step, a halogenation step, and a selective etch step.

[0060] The term “processing chamber” generally represents an enclosure in which chemical and / or physical processes are performed on substrates.

[0061] The term “processing tool” generally represents a machine including a processing chamber and other hardware configured to enable substrate processing to be carried out in the processing chamber.

[0062] The term “radio frequency power” generally represents oscillating electric energy in a radio frequency regime (approximately 20 kHz to 300 GHz).

[0063] The term “showerhead” generally represents a processing chemical outlet comprising a plurality of holes distributed across an area.

[0064] The term “substrate” generally represents any object that can be processed in a processing chamber of a processing tool. Deposition and etching are example processes that can be performed on a substrate in a processing chamber.

[0065] The term “substrate support” generally represents any structure for supporting a substrate in a processing chamber.

[0066] The term “3D DRAM” is an acronym for three-dimensional dynamic random-access memory.

[0067] The term “3D NAND” is an acronym for three-dimensional NOT AND memory, and represents memory architecture based upon NOT AND logic gates.

[0068] As introduced above, semiconductor manufacturing includes many steps of material deposition and removal to form integrated circuits on a substrate. Example deposition processes include atomic layer deposition (ALD) and chemical vapor deposition (CVD). Example etching processes include dry etching and wet etching processes.

[0069] In some device fabrication processes, features are etched into one or more previously deposited material layers. After etching, the features are filled with another material in a deposition process sometimes referred to as “gapfill.” A gapfill process can be used to form dielectric layers between circuits, for example.

[0070] However, gapfill processes can pose various challenges. For example, it can be challenging to fill a high aspect ratio (HAR) feature, such as a feature having an aspect ratio of 5 or greater. Due to the relatively narrow width of an HAR feature compared to the depth of the HAR feature, film precursors may react and form film layers on sidewalls of a HAR feature prior to reaching the bottom of a HAR feature. AsDocket No. LRC24313PPCT such, film growth rates tend to be greater near the opening of a feature than toward the bottom of the feature. This can result in void formation when the growth fronts of the film meet at a location near the opening of the feature and pinch off the feature before deeper regions of the film are fully filled.

[0071] Various techniques can be employed to enhance film growth near the bottom of a feature compared to the top of the feature to avoid such pinch off when performing gapfill. One strategy is to use ALD to conformally grow a film by sequentially adsorbing film precursor to surfaces in the feature and reacting the adsorbed precursor to form film layers. However, ALD gapfill processes can form seams in a feature where film growth fronts meet in the middle of a feature.

[0072] FIGS. 1A-1D schematically show seam formation in an ALD gapfill process. Referring first to FIG. 1 A, substrate 100 comprises a feature 102 that has been formed in substrate 100. Feature 102 can be formed using a patterned hardmask 104 and a directional etching process, such as reactive ion etching (RIE) or directional atomic layer etching (ALE).

[0073] FIG. IB shows partial completion of an ALD process to fill feature 102 with a film 106. The ALD process can be a plasma-enhanced ALD (PEALD) process that utilizes a plasma of a reactive gas to facilitate a chemical conversion of a precursor adsorbed to a substrate to a film on the substrate, or a thermal ALD (TALD) process that uses thermal energy to convert precursor to a film. Film 106 can comprise any suitable material. Examples of gapfill materials for film 106 include silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbide, silicon, molybdenum, germanium, tungsten, titanium, titanium nitride, and tantalum.

[0074] FIG. 1C shows substrate 100 following further ALD processing to fill feature 102 with film 106. However, as the growth fronts of film 106 approach each other from opposite sidewalls of feature 102, there are fewer reactive species and less ion bombardment on film 106 near the center of feature 102. This can lead to a lower density film and / or void formation. For example, where the film 106 comprises an oxide material (e.g., SiCh), terminal OH groups may be present at the seam. Terminal OH groups limit crosslinking and can cause the material to be less dense and / or susceptible to etching. Due to the lack of ion bombardment and reactive species, a seam 110 forms in the center of feature 102. Such seams can be less dense than surrounding gapfill film regions, and thus can be etched at a higher rate in a wet etching process. This can lead to difficulties in downstream wet or dry etching processes.Docket No. LRC24313PPCT

[0075] FIG. ID shows substrate 100 following a etch step to remove the overburden of film 106. Due to the low density of the gapfill material within seam 110, the seam 110 is etched at a higher etch rate than surrounding regions of film 106. As a result, a hole 112 is formed in the remaining film portion 106. This can be referred to as “seam blowout”. Seam blowout can lead to pattern collapse, punchthrough (i.e., exposure of the underlying substrate 100), and / or device failure.

[0076] ALD also can result in pinching off of a feature when a feature comprises a reentrant profile. A reentrant profile (sometimes referred to as “reentrancy” or “reentrant feature”) comprises a feature that is narrower at a location closer to an opening compared to a wider location deeper within the feature. Gapfill of reentrant features can result in void formation. FIGS. 2A-2C schematically show structures formed in an ALD gapfill of a feature comprising a reentrant profile. FIG. 2A shows a substrate 200 comprising a feature 202. As indicated at 204, the feature 202 comprises a reentrant profile.

[0077] FIG. 2B shows substrate 200 following ALD processing to deposit a film 206 within feature 202. Due to the reentrant profile 204, film 206 is beginning to pinch off toward the opening of feature 202. FIG. 2C shows substrate 200 following further ALD processing to deposit additional film 206. This leads to pinch off at the reentrant profile 204 and formation of a void 208. Due to the pinch off of film 206, film precursors do not deposit additional film within void 208.

[0078] Various strategies can be applied to attempt to modify ALD gapfill processes to enhance film growth toward the bottom of a feature and fill the feature in a bottom-up manner. One technique to promote bottom-up film growth is inhibited ALD, where an inhibitor is deposited onto upper surfaces of a feature to slow film growth compared to growth rates deeper in the feature. However, inhibited ALD can be slow. This adds costs to applications that use inhibited ALD gapfill processes. Alternatively or additionally, one or more etching cycles can be performed during a gapfill process to taper a gapfill film in a cyclic deposition / etching process. For example, a fluorine-containing plasma can be used to etch silicon-containing gapfill materials such as SiCh between deposition cycles to shape the gapfill film at intermediate points during deposition. However, it can be difficult to control lateral etching. For example, etching with a continuous fluorine-containing plasma can result in isotropic / conformal etching. While tapered etching may occur near the top of a feature, these methods can lack control over etching deeper in the feature.Docket No. LRC24313PPCT

[0079] Accordingly, examples are disclosed that relate to shaping a feature to address the above-mentioned issues associated with gapfill. Briefly, a layer of gapfill material is deposited on a substrate and within a feature. Then, to shape the layer of gapfill material, one or more etch cycles are performed. An etch cycle comprises a topologically selective deposition of a carbon film on a portion of the gapfill material. Next, a plasma is formed using a halogen-containing etchant to incorporate halogen species (e.g., F or Cl) into at least a portion of the carbon film. The etch cycle further comprises ashing the carbon film. The term “ashing” refers generally to the removal of a carbon film by converting carbon in the carbon film to volatile products, such as carbon oxides (e.g. by using an oxygen-containing plasms) or hydrocarbons (e.g. by using a hydrogen-containing plasma). The ashing process causes the halogen species to etch the gapfill material at locations that were covered by the carbon film. As a result, the gapfill material is selectively etched at locations where the carbon film was selectively deposited, halogenated, and ashed. As described in more detail below, the etch cycle can be repeated to shape a feature. As one example, the etch cycle can be used to taper a gapfill film within feature. This can help avoid seam formation in gapfill applications. As another example, etch cycles can be used to remove a reentrant profile from a feature. This can help avoid void formation in gapfill of reentrant features. Further, the examples disclosed herein can be faster and more cost-effective compared to inhibited deposition processes.

[0080] In addition to cost-savings, the disclosed examples can help produce a higher quality gapfill with greater density and corresponding better etch resistance in the seam compared to other techniques. By increasing the density of the seam and avoiding use of inhibitor chemicals, the disclosed examples can produce high quality oxide films suitable for use in dynamic random-access memory (DRAM) applications. For example, the disclosed etch cycles can be used to shape PEALD films for forming shallow trench isolation (STI) regions in logic applications. Additionally, the disclosed examples can be used in gapfill processes for 3D NAND (three-dimensional NOT AND) and DRAM (dynamic random access) memory device fabrication.

[0081] In various examples, the topologically selective deposition can be performed using plasma-enhanced CVD (PECVD) under processing conditions configured to promote an ion-driven deposition process. Ion-driven deposition can comprise forming a plasma to create carbon species and inert gas ions (e.g., argon ions) in the plasma, and accelerating the ions toward the substrate vertically (i.e.,Docket No. LRC24313PPCT perpendicular to the substrate surface) to deposit and form a carbon film on non-vertical surfaces (e.g., horizontal or sloped surfaces) of the substrate. Further, a relatively low processing pressure (e.g., < 20 Torr) can be utilized to avoid scattering and deposition on other surfaces. Other processing parameters can be tuned to provide further topographical control. For example, the radiofrequency energy used to form the plasma can be tuned to help drive reactive ions in the plasma toward the bottom of the feature. As an example, a radiofrequency plasma can be formed using a multi-frequency plasma with lower-frequency component of radiofrequency power (e.g. below 3MHz) and / or a biasing voltage. PECVD processes that provide directional control can be referred to as “directional PECVD” processes.

[0082] Halogenation of the carbon film can be achieved by forming a plasma using a halogen-containing etchant and exposing the carbon film to halogen species in the plasma. Example halogen-containing etchants include fluorine-containing etchants such as HF and NF3, and chlorine-containing etchants such as HC1. Further examples of halogen-containing etchants are listed above. By incorporating halogen species into the carbon film, the carbon film acts as an etchant reservoir. In the ashing step, halogen stored in the carbon film is driven into the gapfill material, resulting in etching at locations where the halogenated carbon film was formed.

[0083] In some examples, conditions for a halogenating plasma can be adjusted to incorporate halogen species into a selected portion of the carbon film. For example, a halogenating plasma treatment comprising a relatively shorter duration and / or a relatively lower concentration of halogen can be used to halogenate a portion of the carbon film on substrate surfaces near (substantially adjacent to) the opening of a feature. As the ashing step causes etching of the gapfill material at locations where the halogenated carbon film is formed, this can help selectively etch portions of the gapfill material closer to the opening of the feature. Alternatively, the halogenating plasma treatment can be performed for a relatively longer duration and / or utilize a relatively higher concentration of halogen to halogenate portions of the carbon film deeper in the feature. In this manner, the halogenating plasma conditions can provide further control over the selective etching process.

[0084] Performing the etch in a cyclic manner can produce a tapered etch profile in a feature, as carbon in subsequent etch cycles can deposit deeper into the feature. The etch profile can be tuned by controlling various process parameters suchDocket No. LRC24313PPCT as a thickness of the layer of gapfill material, PECVD carbon recipe, carbon film thickness, ashing conditions, process step duration, and number of etch cycle iterations.

[0085] FIG. 3 shows a flow diagram of an example method 300 for performing a topographically selective etch in a gapfill application. Method 300 comprises performing one or more etch cycles during a gapfill process to shape a feature. First, method 300 comprises at 302, depositing a layer of gapfill material on the substrate and within a feature of the substrate. Any suitable gapfill material can be used that can be etched by halogen species (e.g., fluorine species or chlorine species). Examples of gapfill materials include silicon-based materials, metals, metal oxides, and metal nitrides that can react with a halogen to form volatile species. More specific examples of gapfill materials include films comprising silicon (Si), silicon oxide (SiCh), silicon nitride (SiN), silicon oxynitride (SiON), silicon oxycarbide, molybdenum (Mo), germanium (Ge), titanium (Ti), titanium nitride (TiN), titanium dioxide (TiO ), tantalum (Ta), or tantalum oxide (Ta20s). Any suitable method can be used to deposit the layer of gapfill material at 302. In some examples, as indicated at 304, method 300 can comprise depositing the layer of gapfill material using ALD. As discussed above, ALD involves cyclically adsorbing a precursor to the substrate and reacting the adsorbed precursor to form a film layer. More particularly, an ALD cycle can include a dose step to adsorb precursor to the substrate, a purge step to remove excess precursor, a reaction step to convert the precursor to form a film layer, and an optional purge step to remove excess reactants. In various examples, the reaction step can utilize a plasma of a reactive gas (PEALD) or thermal energy (TALD) to facilitate chemical conversion of the precursor to a film on the substrate. Step 304 can comprise any suitable number of ALD cycles to deposit the layer of gapfill material. ALD can help deposit a relatively conformal layer of gapfill material on a substrate and in a feature. In other examples, method 300 comprises depositing the layer of gapfill material using CVD (e.g., PECVD or thermal CVD).

[0086] Method 300 further comprises performing one or more etch cycles 306. Each etch cycle comprises, at 308, performing a topologically selective deposition of a carbon film (e.g., an amorphous carbon film) on portions of the gapfill material. In some examples, the carbon film can be deposited by a PECVD process using one or more carbon-containing precursors. Example carbon-containing precursors include hydrocarbons, such as methane (CEL), ethane (C2H6), propane (CsHs), butane (C4H10), propylene (CsEL), and acetylene (C2H2). Further examples of carbon-containingDocket No. LRC24313PPCT precursors include those listed above. In some examples, O2 is used to help avoid carbon deposition on sidewalls of a features. H2, Ar, and / or N2 also can be used in a gas mixture during carbon deposition.

[0087] The carbon film can be deposited using any suitable method with topological selectivity. As mentioned above, plasma conditions during a PECVD process can be controlled to help promote vertical bombardment of precursor species on non-vertical surfaces of the substrate (directional PECVD) such that the precursor species impact and form the carbon film in an ion-driven deposition process on the nonvertical surfaces of the substrate. Such non-vertical surfaces can include, for example, a bottom surface of a feature between sidewalls of the feature, field regions outside the feature, and / or sloped portions of reentrant features. In some examples, step 308 can be performed using a relatively low pressure to avoid collisions and scattering of ions to non-vertical trajectories. Examples include pressures within a range of 0.5 Torr to 20 Torr. Examples of temperatures for carbon PECVD include temperatures within a range of 100 °C to 650 °C. Unless otherwise stated, all ranges listed herein are inclusive of the endpoints.

[0088] Directional PECVD of the carbon film can utilize any suitable plasma conditions. In some examples, the plasma is a radiofrequency plasma. Examples of frequencies for forming a radiofrequency plasma include frequencies of 400 kHz, 13.56 MHz, 27 MHz, 60 MHz, and 100 MHz. In some examples, the plasma can comprise a higher frequency radiofrequency energy component (“HF component”) and a lower frequency radiofrequency energy component (“LF component”). The LF component can comprise a frequency below 3 MHz. The LF component can comprise a power within a range of 100 W to 1500 W, in some examples. Further, the HF component can comprise frequencies within a range of 3 MHz to 300 MHz. The HF component can comprise a power within a range of 250 W to 1500 W, in some examples. In other examples, values outside these ranges can be used. Unless otherwise stated, values for radiofrequency power refers to power per substrate processing station. Radiofrequency power for a multi-station processing chamber can be scaled accordingly. As mentioned above, the directional PECVD process can include plasma conditions that favor ionbased film formation rather than radical-based film formation. In such examples, the radiofrequency energy can be tuned to help drive reactive carbon ions and argon ions in the plasma toward the bottom of the feature, e.g., by using a multi -frequency plasma with LF component of radiofrequency power and / or a biasing voltage.Docket No. LRC24313PPCT

[0089] Continuing method 300, the etch cycle 306 further comprises, at 310, halogenating the carbon film by forming a plasma using a halogen-containing etchant. Examples include fluorine-containing etchants such as HF, F2, or NF3, and chlorine- containing etchants such as CI2. Additional examples of fluorine-containing etchants and chlorine-containing etchants are listed above. In some examples, an inert gas such as He, Ne, Ar, Kr, or Xe also is used. Exposing the carbon film to the plasma causes halogen species (e.g., F or Cl) to be incorporated into the carbon film, thereby forming a halogenated carbon film. As an example, a plasma can be formed using NF3 and Ar to fluorinate the carbon film and form C-F bonds within the carbon film. In this example, the carbon film can act as a reservoir for fluorine to provide a fluorine-based etch in a later etch step.

[0090] Any suitable plasma conditions can be used at step 310. Examples include pressures of 0.5 Torr to 30 Torr and radiofrequency powers of 100 W to 1000 W. In some examples, a flow rate of the halogen-containing etchant can be 15 to 5000 standard cubic centimeters per minute (seem). In some examples, a flow rate of inert gas can be 10 to 20 standard liters per minute (slm). In other examples, one or more parameters outside of these ranges can be used.

[0091] In some examples, at 312, method 300 comprises selectively halogenating upper portions of the carbon film with a higher concentration of halogen than portions of the carbon film that are deeper within a feature. As used herein, “upper portions” refers to portions of a film disposed on field regions and / or sidewalls near the opening of a feature. For example, carbon film formed on field regions of the substrate can be halogenated while portions of the carbon film formed deeper in the features (e.g., a lower portion of a film on a bottom surface between sidewalls of a feature) are halogenated to a lesser extent (or not halogenated). In some examples, the substrate is exposed to the halogenating plasma for a relatively shorter duration to halogenate upper portions of the carbon film. For example, a halogenating plasma duration of 1 sec or less can be used to selectively halogenate upper portions of the carbon film. In some examples, a relatively lesser partial pressure of halogen-containing etchant can be used. Alternatively, the halogenating plasma treatment can be performed for a relatively longer duration and / or utilize a relatively greater partial pressure of halogen to halogenate portions of the carbon film deeper in the feature.

[0092] Continuing, at 314, etch cycle 306 comprises ashing the carbon film to thereby cause etching of the gapfill material. Ashing the carbon film at step 314 canDocket No. LRC24313PPCT comprise forming an ashing plasma using an oxidant such as oxygen (O2), nitrous oxide (N2O), or ozone (O3) to form one or more volatile carbon oxides, or a reducing agent such as hydrogen (H2) to form one or more volatile hydrocarbons. In some examples, the ashing plasma further can comprise an inert gas. The plasma-driven ashing process causes halogen species stored in the halogenated carbon film to drive into the gapfill material. This causes etching at locations covered by the halogenated carbon film. Other locations are not etched, or can be etched to a lesser extent. Various processing parameters of method 300 can be tuned to help control the etching of the layer of gapfill material. For example, a relatively thicker carbon film can be deposited at step 308 to help store a greater amount of halogen species. This can help achieve a greater etch effect at step 314 compared to use of a relatively thinner carbon film.

[0093] In some examples, the method can comprise densifying the gapfill material by exposing the gapfill material to an ion flux. For example, after ashing the carbon film to etch the gapfill material, a plasma can be formed using an inert gas (e.g., Ar). Inert gas ions can help densify the gapfill material. A gapfill material comprising a greater density can also exhibit better etch resistance. As such, densification of the layer of gapfill material can help avoid seam deterioration in a subsequent etch step.

[0094] Thus, the selective etching of the gapfill material can be used to shape the profile of the layer of gapfill material on the substrate and within the feature. More particular examples related to tapering a feature (FIGS. 4A-4K) and etching a reentrant feature (FIGS. 5A-5H) are described in more detail below.

[0095] The etch cycle 306 can be iterated to help achieve a desired shaping effect. At 320, method 300 comprises determining whether to perform additional etch cycles 306. If “YES”, method 300 returns to step 308 and performs another topologically selective deposition of carbon film. Any suitable number of etch cycles 306 can be performed to shape a feature.

[0096] If instead at 320 it is determined not to perform additional etch cycles 306, method 300 can proceed to 322 and determine whether to deposit additional layers of gapfill material. If “YES”, method 300 can return to step 302 and deposit an additional layer of gapfill material. After depositing an additional layer of gapfill material, method 300 can again perform one or more etch cycles 306 to shape the additional layer of gapfill material. In this manner, method 300 can comprise performing one or more “supercycles”, each supercycle comprising step 302 and oneDocket No. LRC24313PPCT or more etch cycles 306. In such examples, any suitable number of supercycles can be performed.

[0097] On the other hand, if at step 322 it is determined not to deposit additional layers of gapfill material, method 300 can proceed to optional step 324 and deposit additional gapfill material within the feature to complete the gapfill process. In various examples, optional step 324 can comprise a CVD process (e.g., PECVD) or one or more ALD cycles to fill the feature with the gapfill material. In some examples, method 300 can terminate without filling the feature with gapfill material. For example, method 300 can be performed to etch a reentrant feature and form a feature comprising vertical (non-reentrant) sidewalls. After etching the reentrant feature, the substrate can be transferred for additional processing.

[0098] Method 300 can be used in any suitable gapfill application. In some examples, method 300 can be used to fill a trench or hole for a 3D NAND or DRAM device fabrication process. Method 300 further can be used for shallow trench isolation (STI) gapfill for a logic device.

[0099] FIGS. 4A-4K schematically show structures formed in an example process that uses method 300 to taper a film deposited in a feature. FIG. 4 A shows a substrate 400 comprising a feature 402 formed in the substrate. Feature 402 can be formed using a hardmask 404 for patterning. Substrate 400 can comprise any suitable material, such as silicon or germanium. Hardmask 404 can comprise silicon nitride, for example.

[0100] FIG. 4B shows substrate 400 following step 302 to deposit a layer of silicon oxide 406 over substrate 400 and within feature 402. In other examples, a different gapfill material can be used instead of silicon oxide.

[0101] FIG. 4C shows substrate 400 following step 308 to deposit a carbon film 410 using a topologically selective deposition process. Due to the topologically selective deposition conditions, carbon film 410 is formed on non-vertical surfaces. As shown, upper portions of carbon film 410A are formed on field regions 412 to cover a portion of the silicon oxide 406 on the field regions 412. Additionally, a lower portion of carbon film 410B is formed on bottom surface 416 within feature 402 to cover a portion of the silicon oxide 406 on the bottom surface 416. The term “cover” and variants thereof refer to a film portion disposed directly on top of a different film portion. Carbon film 410 is not deposited on sidewalls 418 within feature 402.Docket No. LRC24313PPCT

[0102] FIG. 4D shows substrate 400 following step 310 to expose carbon film 410 to a fluorinating plasma. In the depicted example, a plasma is formed using NF3 and Ar to form F species 420. The plasma exposure incorporates F species into upper portions of the carbon film to form fluorinated carbon film 410C. However, fluorine is not significantly incorporated into the lower portions of carbon film 410B. As discussed above, selective fluorination of upper portions of the carbon film can be achieved by using a relatively short exposure time (e.g., approximately 1 second) and / or a relatively lower partial pressure of the fluorine-containing etchant. A longer plasma exposure time and / or relatively greater partial pressure can be used to fluorinate the portions of carbon film 410B deeper within the features.

[0103] FIG. 4E shows substrate 400 following step 314 to ash the carbon film 410. An ashing plasma can be formed using oxygen or hydrogen, for example, to form volatile carbon oxide species. The ashing plasma drives fluorine species stored in the fluorinated carbon film 410C into the silicon oxide 406 to cause etching of the silicon oxide. The etching causes tapering of feature 402, as dotted lines 422 indicate silicon oxide that has been removed. Thus, FIGS. 4C-4E show the effects of an etch cycle 306 to taper the layer of silicon oxide 406.

[0104] As mentioned above, etch cycles 306 can be performed in a cyclic manner to further taper the feature 402. FIG. 4F shows substrate 400 following a second step 308 to deposit additional carbon film 410 onto non-vertical surfaces of substrate 400 and within feature 402. As the layer of silicon oxide is tapered, the carbon film 410 can deposit deeper into feature 402. FIG. 4G shows substrate 400 following a second step 310 to halogenate upper portions of the carbon film to form halogenated carbon film 410C. FIG. 4H shows substrate 400 following a second step 314 to ash the carbon film and thereby cause etching of the layer of silicon oxide 406 on locations covered by the fluorinated carbon film 410C. As a result of the second etch cycle 306, the silicon oxide 406 is further tapered deeper into the feature 402.

[0105] FIGS. 41, 4J, and 4K shows substrate 400 following a third step 308, a third step 310, and a third step 314 to further taper the layer of silicon oxide 406. After a suitable amount of tapering has been performed, additional silicon oxide 406 can be deposited within feature 402. By tapering the profile of silicon oxide 406, the above- mentioned gapfill issues such as seam formation can be avoided.

[0106] FIGS. 5A-5H schematically show structures formed using method 300 to etch a reentrancy in a feature. FIG. 5A shows a substrate 500 comprising a featureDocket No. LRC24313PPCT502 formed in the substrate. Feature 502 comprises a reentrancy 504 as the width of feature 502 is smaller near the opening of the feature compared to deeper within the feature.

[0107] FIG. 5B shows substrate 500 following step 304 to deposit a layer of silicon oxide using ALD. As a result, the layer of silicon oxide 506 is formed conformally on substrate 500, within feature 502, and over reentrancy 504. Further ALD processing can pinch off at reentrancy 504 and form a void. As such, etch cycles 306 can be performed to etch the reentrant feature.

[0108] FIG. 5C shows substrate 500 following step 308 to deposit a carbon film 510 using a topologically selective deposition process. Due to the topologically selective deposition conditions, carbon film 510 is formed on non-vertical surfaces including field regions 512 and a sloped portion 514 above the reentrancy 504.

[0109] FIG. 5D shows substrate 500 following step 310 to expose carbon film 510 to a fluorinating plasma. The plasma exposure incorporates fluorine species 520 into the carbon film to form fluorinated carbon film 510A.

[0110] FIG. 5E shows substrate 500 following step 314 to ash the fluorinated carbon film 510A using an ashing plasma. The ashing plasma drives fluorine species stored in the fluorinated carbon film 510A into the silicon oxide 506 to cause etching of the silicon oxide. This etches the silicon oxide on field regions 512 and sloped portion 514. By etching the silicon oxide 506 over reentrancy 504, the reentrant profile of feature 502 is reduced.

[0111] Thus, FIGS. 5C-5E show the effect of a first etch cycle 306 to lessen the reentrant profile of feature 502. FIGS. 5F-5H show the effect of a second etch cycle 306. FIG. 5F shows substrate 500 following a second step 308 to deposit additional carbon film 510 onto non-vertical surfaces of substrate 500. FIG. 5G shows substrate 500 following a second step 310 to fluorinate the carbon film to form fluorinated carbon film 510A. FIG. 5H shows substrate 500 following a second step 314 to ash the carbon film and thereby cause etching of the layer of silicon oxide 506 on locations covered by the fluorinated carbon film 510A. As a result of the second etch cycle 306, the silicon oxide 506 is further etched to remove the reentrant profile within feature 502. By removing the reentrant profile, gapfill of feature 502 can be completed without void formation.

[0112] While FIGS. 4A-5H are described in the context of etching a film of silicon oxide with fluorine species, in other examples, a different chemical system canDocket No. LRC24313PPCT be used. As another example, a carbon film can be selectively deposited over a layer of silicon oxynitride. The carbon film can be chlorinated by forming a plasma using Ch and Ar. Then, an ashing plasma can be formed to drive chlorine species stored in the carbon film into the layer of silicon oxynitride to cause etching of the silicon oxynitride at locations covered by the chlorinated carbon film. Additionally, while FIGS. 4A-5H are described in the context of shaping a film deposited within a recessed feature, in other examples, the methods described herein can be used to shape a film deposited on a feature the protrudes out from a surface of a substrate.

[0113] FIG. 6 schematically shows an example processing tool 600 that can implement the examples described above with reference to FIGS. 3-5H. Processing tool 600 comprises a processing chamber 602 and a substrate support 604 within the processing chamber. The substrate support 604 is configured to support a substrate 606 disposed within the processing chamber 602. The substrate support 604 comprises a substrate heater 608. In other examples, a heater can be omitted, or can be located elsewhere within processing chamber 602. In some examples, the substrate heater is configured to heat to a temperature of 100 °C to 650 °C. In other examples, temperatures outside this range can be used.

[0114] The processing tool 600 further comprises a showerhead 610. In other examples, a processing tool can comprise a nozzle or other apparatus for introducing gas into processing chamber 602, as opposed to or in addition to a showerhead. The processing tool 600 further comprises flow control hardware 612. The flow control hardware 612 connects processing gas source(s) to the processing chamber. In the depicted example, the flow control hardware 612 connects a gapfill material film precursor source 616, a carbon-containing precursor source 618, a halogen-containing etchant source 620, an ashing chemical source 622, and an inert gas source 624 to the processing chamber. The flow control hardware 612 can include any suitable components. Examples include mass flow controllers, valves, and conduits. For example, the flow control hardware 612 can comprise one or more valves controllable to place a selected gas source or selected gas sources in fluid connection with showerhead 610. The flow control hardware 612 also can comprise one or more mass flow controllers or other controllers for controlling a mass flow rate of gas.

[0115] The gapfill material film precursor source 616 can comprise any suitable precursor chemical(s) for forming a layer of gapfill material. Examples include silicon- containing precursors for forming silicon-containing films. Examples of silicon-Docket No. LRC24313PPCT containing films include films comprising silicon, silicon oxide, silicon nitride, and silicon oxynitride. Examples of silicon-containing precursors include those listed above. In some examples, a film precursor source can comprise a mixture of chemicals. In other examples, two or more separate film precursor sources can be used to provide a respective two or more film precursors. An example precursor for providing nitrogen for formation of a silicon nitride film or silicon oxynitride film is N2O.

[0116] Further examples of film precursors include germanium-containing precursors, titanium-containing precursors, tungsten-containing precursors, molybdenum-containing precursors, and tantalum-containing precursors for forming germanium-containing films, titanium-containing films, tungsten-containing films, molybdenum-containing films, and tantalum-containing films, respectively.

[0117] The carbon-containing precursor source 618 can comprise any suitable precursor chemical for forming a carbon film (e.g., amorphous carbon). Examples of carbon-containing precursors include hydrocarbons, such as methane, ethane, propane, butane, propylene, and acetylene. Further examples of carbon-containing precursors are listed above.

[0118] The halogen-containing etchant source 620 can comprise any suitable chemical that can form halogen species in a plasma to be incorporated into a carbon film, and that can etch the gapfill material. In some examples, the halogen-containing etchant source comprises a fluorine-containing etchant source 620A. Examples of fluorine-containing etchants include fluorine (F2), hydrogen fluoride (HF), sulfur tetrafluoride (SF4), sulfur hexafluoride (SFe), nitrogen trifluoride (NF3), boron trifluoride (BF3), silicon tetrafluoride (SiF4), phosphorus trifluoride (PF3), phosphorus pentafluoride (PFs), tungsten hexafluoride (WFe), molybdenum hexafluoride (MoFe), fluorocarbons (CxFy), and hydrofluorocarbons ((CxHyFz). Examples of chlorine- containing etchants include chlorine (Ch) and hydrogen chloride (HC1). In some examples, the halogen-containing etchant source 620 comprises a chlorine-containing etchant, such as HC1 or Ch.

[0119] The ashing chemical source 622 can comprise any suitable chemical that can be used to ash a carbon film. Examples include oxidants such as oxygen (O2), nitrous oxide (N2O), or ozone (O3) that can form one or more volatile carbon oxides, or reducing agents such as hydrogen (H2) to form one or more volatile hydrocarbons.

[0120] The inert gas source 624 can comprise any suitable inert gas. Examples include argon, helium, neon, krypton, and xenon.Docket No. LRC24313PPCT

[0121] The processing tool 600 further comprises an exhaust system 632. The exhaust system 632 is configured to exhaust gases from the processing chamber 602. The exhaust system 632 can comprise any suitable hardware, including one or more low vacuum pumps and one or more high vacuum pumps. Together, flow control hardware 612 and exhaust system 632 can be operated to achieve a selected pressure in processing chamber 602 during substrate processing. Further, exhaust system 632 can be operated to purge processing chamber 602.

[0122] The processing tool 600 further comprises a radiofrequency power source 634 that is electrically connected to substrate support 604. Radiofrequency power source 634 is configured to form a plasma using a gas mixture. The processing tool 600 further includes a matching network 636 for impedance matching of the radiofrequency power source 634.

[0123] For example, during a deposition step, radiofrequency power source 634 can be operated to form a plasma using a gas mixture comprising one or more film precursors. Additionally, during a halogenation step, radiofrequency power source 634 can be operated to form a plasma using a gas mixture comprising a halogen-containing etchant to incorporate halogen species into a carbon film. Additionally, radiofrequency power source 634 also is configured to form a plasma comprising an oxidant or reducing agent to ash a carbon film. The showerhead 610 is configured as a grounded opposing electrode in this example. In this example, supplying radiofrequency power to substrate support 604 can increase plasma bias and directionality. This can facilitate directional PECVD of a carbon film, for example. In other examples, the radiofrequency power source 634 can supply radiofrequency power to showerhead 610, and substrate support 604 can be configured as a grounded electrode. Further, the radiofrequency power source 634 can be operated to pulse the plasma, for example, using any suitable duty cycle. Alternatively, the radiofrequency power source 634 can be operated to form a continuous-wave plasma. In the example depicted in FIG. 6, the radiofrequency power source 634 can form a capacitively coupled plasma (CCP) within processing chamber 602. In other examples, a processing tool can be configured to form an inductively coupled plasma (ICP).

[0124] The radiofrequency power source 634 can be configured to provide radiofrequency energy of any suitable frequency and power. Examples frequencies include 400 kHz, 13.56 MHz, 27 MHz, 60 MHz, and 90 MHz. In some examples, the radiofrequency power source 634 is configured to operate at a plurality of differentDocket No. LRC24313PPCT frequencies and / or powers. For example, as described above, a plasma can comprise a LF radiofrequency energy component and a HF radiofrequency energy component. Examples of frequencies for the LF radiofrequency energy component can include frequencies of 3 MHz and below. The LF radiofrequency energy component can comprise a power of 100 to 1500 W, in some examples. Further, the HF radiofrequency energy component can comprise frequencies of 3 MHz to 300 MHz. The HF radiofrequency energy component can comprise a power of 250 to 1500 W, in some examples.

[0125] The processing tool 600 further comprises a controller 650 configured to control operation of the processing tool. The controller 650 is operatively coupled to the substrate heater 608, the flow control hardware 612, the exhaust system 632, and the radiofrequency power source 634.

[0126] The controller 650 is configured to operate the substrate heater 608 to heat a substrate to a desired temperature. Examples include temperatures of 100 °C to 650 °C. The controller 650 further is configured to operate the flow control hardware 612 to flow one or more processing chemicals at selected flow rate(s) to showerhead 610. The controller 650 further is configured to operate the radiofrequency power source 634 to form a plasma in the processing chamber 602 to facilitate film formation, halogenation of a carbon film, etching, or ashing. The controller 650 further is configured to operate the exhaust system 632 to remove gases and / or byproducts from processing chamber 602. The controller 650 further is configured to operate the exhaust system 632 and the flow control hardware 612 to purge the processing chamber 602. The controller 650 further is configured to operate the exhaust system 632 and / or the flow control hardware 612 to maintain a selected pressure within processing chamber 602.

[0127] The controller 650 further is configured to control the processing tool 600 to perform one or more etch cycles 306. The controller 650 further is configured to cause the processing tool to deposit a carbon film on a portion of a gapfill material of a substrate by a topologically selective deposition process. The controller 650 further is configured to cause the processing tool to form a plasma using a halogen-containing etchant to incorporate halogen species from the halogen-containing etchant into the carbon film. The controller 650 further is configured to cause the processing tool to ash the carbon film to thereby cause etching of the gapfill material by the halogen species selectively at locations that were covered by the carbon film. The controller 650 furtherDocket No. LRC24313PPCT is configured to control any other suitable functions of processing tool 600 to implement any of the example method disclosed herein.

[0128] The controller 650 can comprise any suitable computing system. FIG. 7 schematically shows a non-limiting example of a computing system 700 that can enact one or more of the methods and processes described above. Computing system 700 is shown in simplified form. Computing system 700 may take the form of one or more personal computers, workstations, computers integrated with substrate processing tools, and / or network accessible server computers.

[0129] Computing system 700 includes a logic subsystem 702 and a storage subsystem 704. Computing system 700 may optionally include a display subsystem 706, input subsystem 708, communication subsystem 710, and / or other components not shown in FIG. 7. Controller 650 is an example of computing system 700.

[0130] Logic subsystem 702 includes one or more physical devices configured to execute instructions. For example, the logic subsystem may be configured to execute instructions that are part of one or more applications, services, programs, routines, libraries, objects, components, data structures, or other logical constructs. Such instructions may be implemented to perform 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.

[0131] The logic subsystem may include one or more processors configured to execute software instructions. Additionally or alternatively, the logic subsystem may include one or more hardware or firmware logic subsystems configured to execute hardware or firmware instructions. Processors of the logic subsystem may be singlecore or multi-core, and the instructions executed thereon may be configured for sequential, parallel, and / or distributed processing. Individual components of the logic subsystem optionally may be distributed among two or more separate devices, which may be remotely located and / or configured for coordinated processing. Aspects of the logic subsystem may be virtualized and executed by remotely accessible, networked computing devices configured in a cloud-computing configuration.

[0132] Storage subsystem 704 includes one or more physical devices configured to hold instructions 712 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 704 may be transformed — e.g., to hold different data.Docket No. LRC24313PPCT

[0133] Storage subsystem 704 may include removable and / or built-in devices. Storage subsystem 704 may 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 704 may include volatile, nonvolatile, dynamic, static, read / write, read-only, random-access, sequential-access, location-addressable, file-addressable, and / or content-addressable devices.

[0134] It will be appreciated that storage subsystem 704 includes one or more physical devices. However, aspects of the instructions described herein alternatively may 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.

[0135] Aspects of logic subsystem 702 and storage subsystem 704 may be integrated together into one or more hardware-logic components. Such hardware-logic components may 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.

[0136] When included, display subsystem 706 may be used to present a visual representation of data held by storage subsystem 704. This visual representation may 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 706 may likewise be transformed to visually represent changes in the underlying data. Display subsystem 706 may include one or more display devices utilizing virtually any type of technology. Such display devices may be combined with logic subsystem 702 and / or storage subsystem 704 in a shared enclosure, or such display devices may be peripheral display devices.

[0137] When included, input subsystem 708 may comprise or interface with one or more user-input devices such as a keyboard, mouse, or touch screen. In some examples, the input subsystem may comprise or interface with selected natural user input (NUI) componentry. Such componentry may be integrated or peripheral, and the transduction and / or processing of input actions may be handled on- or off- board. Example NUI componentry may include a microphone for speech and / or voiceDocket No. LRC24313PPCT recognition, and an infrared, color, stereoscopic, and / or depth camera for machine vision and / or gesture recognition.

[0138] When included, communication subsystem 710 may be configured to communicatively couple computing system 700 with one or more other computing devices. Communication subsystem 710 may include wired and / or wireless communication devices compatible with one or more different communication protocols. As non-limiting examples, the communication subsystem may 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 may allow computing system 700 to send and / or receive messages to and / or from other devices via a network such as the Internet.

[0139] 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 may represent one or more of any number of processing strategies. As such, various acts illustrated and / or described may be performed in the sequence illustrated and / or described, in other sequences, in parallel, or omitted. Likewise, the order of the above-described processes may be changed.

[0140] 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

Docket No. LRC24313PPCTCLAIMS:

1. A method for shaping a film of a gapfill material on a feature of a substrate, the method comprising: performing a topologically selective deposition of a carbon film on a portion of the gapfill material; forming a plasma using a halogen-containing etchant to incorporate halogen species from the halogen-containing etchant into the carbon film to form a halogenated carbon film; and ashing the carbon film to thereby cause etching of the gapfill material by the halogen species selectively at locations that were covered by the halogenated carbon film.

2. The method of claim 1, wherein ashing the carbon film to cause etching of the gapfill material comprises forming a tapered profile within the feature.

3. The method of claim 2, further comprising, after ashing the carbon film, densifying the gapfill material by exposing the gapfill material to an ion flux.

4. The method of claim 1, further comprising, prior to performing the topologically selective deposition of the carbon film on the portion of the gapfill material, depositing the gapfill material on the substrate to form a reentrant profile within the feature, and wherein etching the gapfill material etches the reentrant profile of the feature.

5. The method of claim 1, further comprising, after ashing the carbon film, depositing an additional layer of the gapfill material on the substrate and within the feature of the substrate; and cyclically repeating the topologically selective deposition of the carbon film, the forming of the plasma to incorporate the halogen species into the carbon film, the ashing of the carbon film, and the depositing of the additional layer of the gapfill material to fill the feature.

6. The method of claim 1, wherein the topologically selective deposition of the carbon film on the portion of the gapfill material comprises depositing the carbon film using an ion-driven deposition process.Docket No. LRC24313PPCT7. The method of claim 1, wherein performing the topologically selective deposition of the carbon film on the portion of the gapfill material comprises forming a plasma using a hydrocarbon.

8. The method of claim 1, wherein the plasma is formed using hydrogen fluoride, fluorine, nitrogen trifluoride, sulfur tetrafluoride, sulfur hexafluoride, xenon difluoride, hydrogen chloride, chlorine, and combinations thereof.

9. The method of claim 1, wherein ashing the carbon film comprises forming a plasma using oxygen (O2), hydrogen (H2), nitrous oxide (N2O), ozone (O3), and combinations thereof.

10. The method of claim 1, wherein the gapfill material comprises silicon, silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbide, molybdenum, tungsten, germanium, titanium, titanium nitride, tantalum, and combinations thereof.

11. The method of claim 1, wherein forming the plasma using the halogencontaining etchant comprises incorporating a first concentration of the halogen species into a first location of the carbon film, and incorporating a second concentration of the halogen species into a second location of the carbon film, the first concentration being greater than the second concentration and the first location being closer to an opening of the recessed feature than the second location.

12. A method of depositing a film of gapfill material in a recessed feature of a substrate, the method comprising:(a) depositing a layer of gapfill material on the substrate and within the recessed feature of the substrate;(b) performing a topologically selective deposition of a carbon film on a portion of the gapfill material;(c) forming a plasma using a halogen-containing etchant to incorporate halogen species from the halogen-containing etchant into the carbon film;(d) ashing the carbon film to thereby cause etching of the gapfill material by the halogen species selectively at locations that were covered by the carbon film; andDocket No. LRC24313PPCT(e) cyclically repeating (b), (c), and (d) for one or more process cycles to shape the layer of gapfill material within the recessed feature.

13. The method of claim 12, wherein forming the plasma using the halogencontaining etchant comprises incorporating a first concentration of the halogen species into a first location of the carbon film, and incorporating a second concentration of the halogen species into a second location of the carbon film, the first concentration being greater than the second concentration and the first location being closer to an opening of the recessed feature than the second location.

14. The method of claim 12, wherein forming the plasma using the halogencontaining etchant comprises incorporating one of fluorine species or chlorine species into the carbon film.

15. The method of claim 12, further comprising cyclically repeating (a), (b), (c), and (d) for one or more process cycles to at least partially fill the recessed feature.

16. The method of claim 15, wherein performing the topologically selective deposition of the carbon film comprises depositing the carbon film using an ion-driven deposition process comprising forming a plasma using argon and a hydrocarbon and a processing pressure within a range of 0.5 Torr to 20 Torr.

17. A processing tool, comprising: a processing chamber; a substrate support disposed in the processing chamber; a substrate heater configured to heat a substrate positioned on the substrate support; a power source configured to form a plasma in the processing chamber; a showerhead configured to introduce processing chemicals into the processing chamber; flow control hardware configured to deliver processing chemicals to the showerhead; and a controller configured to control the processing tool toDocket No. LRC24313PPCT cause the processing tool to deposit a carbon film on a portion of a gapfill material of a substrate by a topologically selective deposition process, cause the processing tool to form a plasma using a halogen-containing etchant to incorporate halogen species from the halogen-containing etchant into the carbon film, and cause the processing tool to ash the carbon film to thereby cause etching of the gapfill material by the halogen species selectively at locations that were covered by the carbon film.

18. The processing tool of claim 17, wherein the controller is further configured to cause the processing tool to deposit the layer of gapfill material on the substrate and within the feature of the substrate.

19. The processing tool of claim 17, wherein the controller is configured to cause the processing tool to form the plasma using the halogen-containing etchant under processing conditions configured to incorporate a first concentration of the halogen species into upper portions of the carbon film near the opening of the recessed feature, and incorporate a second concentration of the halogen species into lower portions of the carbon film near the bottom of the recessed feature, the first concentration being greater than the second concentration.

20. The processing tool of claim 17, wherein the gapfill material comprises silicon, silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbide, molybdenum, tungsten, germanium, titanium, titanium nitride, tantalum, or combinations thereof, and wherein forming the plasma using the halogen-containing etchant comprises forming the plasma using hydrogen fluoride, fluorine, nitrogen trifluoride, sulfur tetrafluoride, sulfur hexafluoride, xenon difluoride, hydrogen chloride, chlorine, and combinations thereof.

Images