Seam-free gapfill by inhibited atomic layer deposition

Abstract

Examples are disclosed that relate to the use of inhibited plasma-enhanced atomic layer deposition (PEALD) comprising sputtering to fill a gap in a substrate. One example provides a method comprising performing a plurality of PEALD cycles. A PEALD cycle comprises, in an inhibition step, forming a plasma using a gas mixture comprising an inhibitor to deposit inhibitor into a gap on a substrate such that a concentration of the inhibitor deposited at a first depth is greater than a concentration of the inhibitor deposited deeper within the gap. The PEALD cycle further comprises, in a deposition step, adsorbing a silicon-containing film precursor to the substrate, and forming a plasma to convert the silicon-containing film precursor into a silicon-containing film within the gap. At least one of the inhibition step or the deposition step comprises exposing the substrate to a plasma under conditions configured to sputter the silicon-containing film.

Description

SEAM-FREE GAPFILL BY INHIBITED ATOMIC LAYER DEPOSITIONBACKGROUND

[0001] Electronic device fabrication processes involve many steps of material deposition, patterning, and removal to form integrated circuits on substrates. Various methods can be used to process films of materials to form integrated circuits. For example, atomic layer deposition (ALD) can be used to form a film on a substrate in a layer-by-layer manner. ALD can be used to form highly conformal films on complex substrate topologies.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 the use of inhibited plasma- enhanced atomic layer deposition (PEALD) comprising sputtering to fill a recessed structure (“gap”) in a substrate. One example provides a method of processing a substrate comprising a gap. The method comprises performing a plurality of PEALD cycles to deposit a silicon-containing film into the gap. A PEALD cycle of the plurality of PEALD cycles comprises, in an inhibition step, forming a plasma using a gas mixture comprising an inhibitor to expose the substrate to the inhibitor under conditions configured to deposit inhibitor into the gap such that a concentration of the inhibitor deposited at a first depth within the gap is greater than a concentration of the inhibitor deposited at a second depth within the gap, the second depth being deeper in the gap than the first depth. The PEALD cycle of the plurality of PEALD cycles further comprises, in a deposition step, adsorbing a silicon-containing film precursor to the substrate, the inhibitor causing a lesser concentration of the silicon-containing film precursor to adsorb at the first depth than at the second depth. The PEALD cycle of the plurality of PEALD cycles further comprises, in the deposition step, forming a plasma to convert the silicon-containing film precursor adsorbed to the substrate into a silicon-containing film within the gap. At least one of the inhibition step or the deposition step comprises exposing the substrate to a plasma under conditions configured to sputter the silicon-containing film.

[0004] In some such examples, the plasma conditions are configured to sputter a portion of the silicon-containing film material from the first depth within the gap and redeposit at least some of the portion of the silicon-containing film material at the second depth within the gap.

[0005] In some such examples, the inhibition step additionally or alternatively is performed at a first pressure of 5 Torr or lower, and the deposition step is performed at a second pressure equal to or greater than the first pressure.

[0006] In some such examples, the deposition step additionally or alternatively is performed at a first pressure of 2 Torr or lower, and the inhibition step is performed at a second pressure of 5 Torr or greater.

[0007] In some such examples, the plasma conditions configured to sputter the silicon-containing film additionally or alternatively include a plasma formed using a radiofrequency power of 1000 W to 6000 W.

[0008] In some such examples, the method additionally or alternatively comprises heating a substrate to a temperature of 50 to 650 °C.

[0009] In some such examples, the substrate additionally or alternatively comprises a first fin and a second fin with the gap disposed therebetween, and the first fin and the second fin each deflect less than 0.5 nm from vertical as measured at a top of the first fin and a top of the second fin upon completion of depositing the silicon- containing film into the gap.

[0010] In some such examples, the substrate additionally or alternatively comprises silicon and germanium, and the deposition step is performed under conditions configured to avoid oxidization of the germanium.

[0011] In some such examples, the silicon-containing film additionally or alternatively comprises one of silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, silicon oxycarbide, silicon carbonitride, or silicon oxycarbonitride.

[0012] In some such examples, the inhibitor additionally or alternatively comprises one or more of nitrogen, hydrogen, ammonia, or nitrogen trifluoride.

[0013] In some such examples, forming the plasma to convert the silicon- containing film precursor into a silicon-containing film additionally or alternativelycomprises forming a plasma using an oxidant comprising one or more of nitrous oxide or carbon dioxide at a concentration that is greater than a concentration of oxygen.

[0014] In some such examples, a PEALD cycle of the plurality of PEALD cycles additionally or alternatively omits the inhibition step.

[0015] Another example provides an atomic layer deposition (ALD) tool. The ALD tool comprises a processing chamber. The ALD tool further comprises a substrate support disposed in the processing chamber. The ALD tool further comprises flow control hardware configured to control flow of gas from an inhibitor source, a silicon- containing film precursor source, and an inert gas source into the processing chamber. The ALD tool further comprises a radiofrequency power source configured to form a plasma in the processing chamber. The ALD tool further comprises a controller configured to control the ALD tool to, in an inhibition step, operate the flow control hardware to flow the inhibitor into the processing chamber. The controller is further configured to, in the inhibition step, operate the radiofrequency power source to form a plasma under conditions configured to deposit inhibitor within a gap on a substrate such that a concentration of the inhibitor deposited at a first depth within the gap is greater than a concentration of the inhibitor deposited at a second depth within the gap, the second depth being deeper in the gap than the first depth. The controller is further configured to, in a deposition step, operate the flow control hardware to flow the silicon- containing film precursor to the processing chamber to adsorb the silicon-containing film precursor on the substrate. The controller is further configured to, in the deposition step, operate the radiofrequency power source form a plasma to oxidize the film precursor to form a layer of an oxide film. The controller is further configured to, in one or more of the inhibition step or the deposition step, operate the flow control hardware and the radiofrequency power source to form a plasma using one or more of the inhibitor, an oxidant, nitrogen, or an inert gas under conditions configured to sputter the silicon-containing film.

[0016] In some such examples, the controller is configured to, in the inhibition step, operate the flow control hardware to form a first pressure in the processing chamber of 5 Torr or lower, and, in the deposition step, operate the flow control hardware to form a second pressure in the processing chamber equal to or greater than the first pressure.

[0017] In some such examples, the controller additionally or alternatively is configured to, in the inhibition step, operate the flow control hardware to form a firstpressure in the processing chamber of 5 Torr or greater, and, in the deposition step, operate the flow control hardware to form a second pressure in the processing chamber of 2 Torr or lower.

[0018] In some such examples, the ALD tool additionally or alternatively further comprises the inhibitor source comprising the inhibitor, the inhibitor comprising one or more of nitrogen, hydrogen, ammonia, or nitrogen trifluoride.

[0019] Another example provides, a method of processing a substrate comprising a gap. The method comprises heating the substrate to a temperature of 650 °C or lower. The method further comprises performing a plurality of plasma-enhanced atomic layer deposition (PEALD) cycles while heating the substrate to deposit a silicon- containing film into the gap. A PEALD cycle of the plurality of PEALD cycles comprises, in an inhibition step, forming a plasma using a gas mixture comprising an inhibitor to expose the substrate to the inhibitor under conditions configured to deposit inhibitor into the gap such that a concentration of the inhibitor deposited at a first depth within the gap is greater than a concentration of the inhibitor deposited at a second depth within the gap, the second depth being deeper in the gap than the first depth. The PEALD cycle further comprises, in a deposition step, exposing the substrate to a silicon-containing film precursor to adsorb silicon-containing film precursor on the substrate, the inhibitor causing a lesser concentration of the silicon-containing film precursor to adsorb at the first depth than at the second depth. The PEALD cycle further comprises, in the deposition step, forming a plasma to convert the silicon-containing film precursor into a silicon-containing film within the gap. At least one of the inhibition step or the deposition step comprises exposing the substrate to a plasma comprising one or more of the inhibitor, an oxidant, nitrogen, or an inert gas under plasma conditions configured to sputter the silicon-containing film as the silicon- containing film grows to avoid formation of a seam in the silicon-containing film within the gap.

[0020] In some such examples, the inhibition step is performed at a first pressure of 5 Torr or lower, and the deposition step is performed at a second pressure equal to or greater than the first pressure.

[0021] In some such examples, the deposition step is performed at a first pressure of 2 Torr or lower, and the inhibition step is performed at a second pressure of 5 Torr or greater.

[0022] In some such examples, the substrate additionally or alternatively comprises a first fin and a second fin with the gap disposed therebetween, and the first fin and the second fin each deflect less than 0.5 nm from vertical as measured at a top of the first fin and a top of the second fin upon completion of depositing the silicon- containing film into the gap.BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIGS. 1A-1E schematically show structures formed on a substrate in an example atomic layer deposition (ALD) gapfill process that results in seam formation.

[0024] FIGS. 2A-2C schematically show structures formed in an example ALD process in which uneven gapfill leads to the deformation of fins on a substrate.

[0001] FIG. 3 shows a flow diagram of an example plasma-enhanced ALD (PEALD) process.

[0002] FIGS. 4A-4E show example structures formed using the PEALD process of FIG. 3 to perform gapfill while avoiding fin displacement and seam formation.

[0003] FIG. 5 shows a flow diagram depicting an example method for processing a substrate comprising a gap.

[0004] FIG. 6 schematically shows an example PEALD tool.

[0005] FIG. 7 shows a block diagram of an example computing device.DETAILED DESCRIPTION

[0006] The term “aspect ratio” generally represents a ratio between a depth of a feature and an average width of the feature.

[0007] 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 to a substrate to a film on the substrate. The terms “growth” and “deposition”, and variants thereof, also can be used to refer to film formation.

[0008] The term “PEALD cycle” generally represents a sequence of processes used to form one layer of a film in a PEALD process.

[0009] The term “ALD tool” generally represents a machine comprising a processing chamber and other hardware configured to perform ALD processing.

[0010] The term “fin” generally represents a structure extending from a substrate surface.

[0011] The term “gap” generally represents a recessed structure on a substrate. A gap can be located between fins.

[0012] The term “inhibition” and variants thereof generally represent a process by which a compound can disrupt one or more chemical processes for film growth on a substrate surface, thereby slowing growth of the film.

[0013] The term “inhibitor” generally represents a compound that can be introduced into a processing chamber to adsorb to a substrate surface to inhibit film growth on the substrate surface. The term “inhibitor” is used herein to represent an inhibitor compound introduced into a processing chamber, reactive inhibitor species formed in a plasma, and adsorbed inhibitor on a substrate surface. Suitable inhibitors include hydrogen (H2), nitrogen-containing inhibitors, fluorine-containing inhibitors, and carbon-containing inhibitors.

[0014] Examples of suitable nitrogen-containing inhibitors can include nitrogen (N2), ammonia (NEE), amines, diamines, and aminoalcohols.

[0015] Examples of suitable fluorine-containing inhibitors can include fluorine (F2), nitrogen trifluoride (NF3), sulfur hexafluoride (SFe), hydrogen fluoride (HF), xenon difluoride (XeF2), and fluorocarbons such as tetrafluoromethane (CF4) or hexafluoroethane (C2F6).

[0016] Examples of suitable carbon-containing inhibitors can include alkanes, alkenes, alkynes, cyclic hydrocarbons, aromatics, alcohols, aldehydes, esters, ethers, ketones, aldehydes, alkyl halides, alkyl amines, and alkyl diamines.

[0017] The term “processing chamber” generally represents an enclosure in which chemical and / or physical processes are performed on substrates.

[0018] The terms “purge” and variants thereof generally represent processes in which unwanted species are removed from a processing chamber.

[0019] The term “showerhead” generally represents a processing chemical outlet comprising a plurality of holes distributed across an area.

[0020] The term “silicon-containing film precursor” generally represents any compound that can be introduced into a processing chamber in a gas phase to form a silicon-containing film on the substrate. Example silicon-containing films includesilicon oxide, silicon nitride, silicon oxynitride, silicon carbide, silicon oxycarbide, silicon carbonitride, and silicon oxycarbonitride. Example silicon-containing film precursors for forming silicon-containing films using PEALD can comprise materials having the general structure:where Ri, R2 and R3 can be the same or different substituents. In various examples, Ri, R2, and R3 can include silanes, siloxy groups, amines, halides, hydrogen, or organic groups such as alkylamines, alkoxy, alkyl, alkenyl, alkynyl, and cyclic groups (such as aromatic groups).

[0021] Example silicon-containing film precursors include silane and polysilanes (H3Si-(SiH2)n-SiH3), where n > 0, such as disilane, trisilane, and tetrasilane, and trisilylamine.

[0022] In some examples, the silicon-containing film precursor is an alkoxysilane. Alkoxysilanes that can be used include compounds having a general formula of Hx-Si-(OR)y, where x = 1-3, x+y = 4 and each R is a substituted or unsubstituted aliphatic or aromatic group; and Hx(RO)y,-Si-Si-(OR)yHx, where each R is a substituted or unsubstituted aliphatic or aromatic group. Example alkoxysilanes include tetramethoxysilane (TMOS), diethoxymethylsilane (DEMS), diethoxysilane (DES), dimethoxymethylsilane, dimethoxysilane (DMOS), methyl-diethoxysilane (MDES), methyl-dimethoxysilane (MDMS), t-butoxy di silane, triethoxysilane (TES), and trimethoxysilane (TMS or TriMOS).

[0023] In some examples, the silicon-containing film precursor is a siloxane. Siloxanes include materials having Si-O-Si linkages. Example siloxanes include octamethylcyclotetrasiloxane (OMCTS), octamethoxydodecasiloxane (OMODDS), and tetramethylcyclotetrasiloxane (TMCTS).

[0024] In some examples, the silicon-containing film precursor is an aminosilane. Aminosilanes include materials having a general formula Hx-Si-(NR)y, where x = 1-3, x+y = 4, and R is a substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aromatic group, or hydride group. Example aminosilanes includebisdiethylaminosilane, diisopropylaminosilane, bis(t-butylamino) silane (BTBAS), di- sec-butylaminosilane, and tris(dimethylamino)silane (3DMAS).

[0025] In some examples, the silicon-containing film precursor is a halogencontaining silane. In some examples, a halogen-containing silane can comprise at least one hydrogen atom. Such a silane can have a general formula of SiXaHy where y > 1. Example halosilanes include dichlorosilane (EhSiCh), hexachlorodisilane (Si2Cle), and diiodosilane (H2SH2).

[0026] More specific examples of silicon-containing film precursors include polysilanes ((SinH2n+2, where n >1, such as silane, disilane, trisilane, and tetrasilane), trisilylamine, tetraethyl orthosilicate (TEOS), methylsilane, trimethylsilane (3MS), ethylsilane, butasilanes, pentasilanes, octasilanes, heptasilane, hexasilane, cyclobutasilane, cycloheptasilane, cyclohexasilane, cyclooctasilane, cyclopentasilane, l,4-dioxa-2,3,5,6-tetrasilacyclohexane, triethoxysiloxane (TRIES), and tetraoxymethylcyclotetrasiloxane (TOMCTS).

[0027] An example precursor for providing nitrogen for formation of a silicon nitride film is nitrogen (N2). An example precursor for providing nitrogen and oxygen for formation of a silicon oxynitride film is N2O.

[0028] In some examples, an oxidant is used to react with the silicon-containing film precursor. Examples include molecular oxygen (O2), water (H2O), hydrogen peroxide (H2O2), ozone (O3), carbon dioxide (CO2), and nitrogen oxides such as nitrous oxide (N2O).

[0029] The term “sputtering” and variants thereof generally represent processes in which ions in a plasma are accelerated toward a substrate with sufficient kinetic energy to cause at least some material on the substrate to be ejected from the substrate upon collision with the substrate.

[0030] The terms “high sputter” and “low sputter” are used below to describe the relative magnitudes of the sputtering effects in inhibition and deposition steps of an ALD cycle according to the present disclosure. These terms are relative to one another. A high sputter step comprises conditions configured to modify a film on a substrate by sputtering. A low sputter step comprises conditions configured to avoid modification of a film on a substrate by sputtering (although some sputtering may occur).

[0031] The term “substrate” generally represents any object on which a film can be deposited.

[0032] The term “substrate support” generally represents any structure for supporting a substrate in a processing chamber.

[0033] As mentioned above, atomic layer deposition (ALD) can be used to fill a gap on a substrate. ALD involves performing one or more deposition cycles to grow a thin film on a substrate surface. Plasma enhanced ALD (PEALD) utilizes a plasma to facilitate deposition of a film. Examples of films that can be deposited by PEALD include oxide films. For example, during a PEALD oxide film deposition cycle, a film precursor gas is introduced into a processing chamber and adsorbs onto a substrate in a self-limiting reaction. Next, the processing chamber is purged to remove excess film precursor. Then, an oxidant is introduced to the processing chamber. A plasma is formed by application of radiofrequency power to electrodes within the processing chamber. The plasma forms reactive oxygen species from the oxidant. The reactive oxygen species react with the film precursor to form a layer of the oxide film. Thermal ALD (TALD) utilizes substrate temperature to drive the chemical reactions that form the oxide film.

[0034] ALD can be used to fill a gap in a substrate with a material, such as a dielectric film. However, seams can form during gapfill processed performed by ALD. FIGS. 1 A-1E schematically show structures formed in an example ALD gapfill process. In the process of FIGS. 1A-1E, a gap between spacers on a substrate is filled with an oxide film using ALD (e.g. PEALD), and then the oxide film is etched. Example oxide films include silicon oxide, silicon oxynitride, and silicon oxycarbide.

[0035] First referring to FIG. 1A, substrate 100 comprises fins 104, 105, 106. Gaps are located between the fins. For example, gap 110 is located between fin 104 and fin 105. Similarly, gap 112 is located between fin 105 and fin 106. Fins 104, 105, 106 can comprise any suitable material.

[0036] In an ALD oxide gapfill process, substrate 100 is positioned in a processing chamber and is exposed to a film precursor gas. The film precursor gas diffuses into gaps 110, 112 and adsorbs onto substrate surfaces. The processing chamber next is purged. Then, an oxidant is introduced into the plasma chamber. By the application of a plasma and / or heat, the adsorbed film precursor reacts with the oxidant to form an oxide film on the surfaces within the gap 110, 112. Repeated cycles of adsorption and oxidation steps progressively fill the gaps 110, 112. FIG. IB schematically shows an oxide film 114 formed on substrate 100. Oxide film 114 is formed using one or more ALD cycles. As shown, oxide film 114 is depositedconformally on surfaces within gap 110 and gap 112 and on fins 104, 105, 106. Additional ALD cycles can be repeated to progressively fill gap 110 and gap 112 with a conformal film. FIG. 1C shows further conformal deposition of oxide film 114 resulting from additional ALD cycles. As shown in FIG. 1C, conformal growth of oxide film 114 leads to narrowing of gap 110 and gap 112.

[0037] However, deposition of an oxide film by ALD in a gapfill process can result in formation of a seam in oxide film 114. FIG. ID shows a seam 120 that has formed in gap 110. Likewise, gap 112 comprises a seam 122. In some examples, a seam can lead to the formation of a void between fins. Oxide materials can comprise terminal OH groups in seams. Terminal OH groups limit crosslinking. Further, oxide material within seams can be low density. Such properties can cause problems during a subsequent etching step.

[0038] FIG. IE schematically shows the result of etching substrate 100 to expose fins 104, 105, 106. Etching oxide film 114 leaves oxide film portion 114A between fins 104 and 105 and oxide film portion 114B between fins 105 and 106. However, due to low density and terminal OH groups within the seam, the material at the seam is etched at a faster rate compared to etch rates at other locations. Terminal OH groups can limit forming oxygen bridging bonds within the seam. As such, etching to expose fins 104, 105, 106 also etches seams 120, 122. As a result, instead of evenly etching the surface of oxide film 114 downwardly, holes 130, 132 are formed in remaining oxide film portions 114A, 114B, respectively. This can be referred to as “seam blowout” or “blowout”. This can lead to pattern collapse and / or a missed pattern after transfer. Additionally, further processing can lead to further etching of the oxide film portions 114A, 114B within holes 130, 132 to expose substrate 100. This is sometimes referred to as “punchthrough”.

[0039] In some such examples, a deposited film can be made seam-free by annealing at > 650 °C. Annealing can help densify the seam portion to avoid higher etch rates in the seam. This can help to avoid pattern collapse and punchthrough. However, due to high temperature of the annealing, the substrate can suffer from thermal oxidation and species migration. For example, a substrate can comprise germanium (Ge). Ge can diffuse and / or be oxidized during high temperature annealing > 600 °C. Thermal oxidation and migration of Ge each can create device performance issues.

[0040] Accordingly, examples are provided that relate to performing seam-free gapfill by using plasma-enhanced ALD (PEALD) with an inhibition step. Briefly, aplurality of PEALD cycles are performed to deposit a silicon-containing film into a gap. In an inhibition step of a PEALD cycle, a plasma is formed using a gas mixture comprising an inhibitor. The processing conditions are configured to adsorb a greater concentration of inhibitor to substrate surfaces within the gap at a first depth and a lesser concentration of inhibitor at a second depth, where the second depth is deeper within the gap than the first depth. In a deposition step of the PEALD cycle, a silicon- containing film precursor is adsorbed on the substrate and a plasma is formed to convert the silicon-containing film precursor into a silicon-containing film within the gap. Due to the inhibitor, the film growth rate is greater at the second, deeper depth within the gap than at the first depth. In this manner, the silicon-containing film can fill the gap in a bottom-up approach to avoid formation of a seam. Further, the process can be performed at a temperature of 600 °C or lower. This can help avoid diffusion and thermal oxidation where Ge is present in the substrate. Further, the PEALD process can be performed under low-oxidizing conditions to further avoid Ge oxidation. For example, carbon dioxide (CO2) and / or nitrous oxide (N2O) can be used in place of oxygen to reduce oxidation of substrate materials. In some examples, EE can be added to the plasma gas mixture to help provide low-oxidizing conditions. Additionally, forming a plasma using relatively lower-power radiofrequency energy also can help reduce oxidation compared to the use of relatively higher-power radiofrequency energy. Example PEALD processes are described in more detail below.

[0041] Other issues than seams can arise when performing gapfill. For example, in some processes, gaps on a substrate can be separated by fins. However, the fins can be displaced from a vertical orientation during gapfill processes. FIGS. 2A-2C schematically show damage caused to a substrate due to fin displacement. First referring to FIG. 2A, substrate 200 comprises fins 202, 204, 206, 208. A gap 210 is located between fin 202 and fin 204. Similarly, a gap 212 is located between fin 204 and fin 206. Further, a gap 214 is located between fin 206 and fin 208. Gap 212 is narrower than gap 210 and gap 214. Fins 202, 204, 206, 208 can comprise any suitable material. In some examples, fins 202, 204, 206, 208 comprise a semiconductor material. Examples include silicon (Si), germanium (Ge), and silicon germanium (SiGe). In some examples, fins 202, 204, 206, 208 comprise a liner, such as a SiCh liner or a SislSk liner.

[0042] FIG. 2B shows substrate 200 comprising a film 220 formed by an arbitrary number of ALD cycles. Due to the spacing of fins 202, 204, 206, 208, gap 212 is smaller than gaps 210 and 214. As a result, film 220 deposits within gap 212 at arelatively faster rate than into gaps 210 and 214. This can lead to unbalanced forces on different sides of one or more of fins 202, 204, 206, and / or 208. FIG. 2C shows substrate 200 following additional ALD cycles. Gap 212 completely fills before gaps 210, 214. As a result, fins 204, 206 are pulled together in a so-called “zippering” effect, indicated at 222. This displaces fins 204, 206, and can damage the substrate 200.

[0043] Accordingly, examples are disclosed that relate to performing an ALD process to deposit a silicon-containing film in a gap that can avoid the issues described above. In various examples, processing conditions during the inhibition step and / or the deposition step of an ALD cycle are configured to sputter the deposited silicon- containing film. Sputtered film material can be ejected off the substrate, and / or redeposit onto other surfaces within the gap. Due to angular dependence on sputter rates, the sidewall surfaces within the gap are sputtered with a V-shape profile. Further, the inhibitor causes film growth rates to be greater at the second, deeper depth within the gap than at the first depth. The combination of the inhibition step and sputtering of the film during the ALD process results in a V-shaped film growth in which the film grows in a bottom-up manner within a gap, rather than conformally. This helps to avoid seams. Further, the sputtered film material can redeposit onto inhibited surfaces within the gap. As a result of sputtering in combination with inhibition, the net effect is more even film growth in gaps that have different widths. Sputtering can be achieved by forming a plasma comprising a gas, such as an inert gas, to expose the deposited film to energetic gas ions. In some examples, use of a relatively heavier inert gas (e.g. Ar) can provide for a higher rate of sputtering compared to a relatively lighter inert gas (e.g. He). In some examples, an inhibitor, an oxidant, and / or nitrogen can be used in a sputter gas in addition to, or alternatively to, an inert gas. Sputtering also can be controlled by adjusting pressure, radiofrequency power, duration of applied radiofrequency power, a showerhead temperature, and / or a spacing between the electrodes used to form a capacitively coupled plasma during PEALD (e.g. a showerhead electrode and substrate support electrode).

[0044] For example, a relatively lower processing chamber pressure can be used to increase a rate of sputtering compared to a relatively higher processing chamber pressure. Ions have a relatively longer mean free path at relatively lower pressures than at relatively higher pressures. This can provide for a relatively higher flux of inert gas ions at the substrate surface compared to the use of relatively higher processing chamber pressures.

[0045] As another example, the use of a higher radiofrequency power to form the plasma can increase the concentration of inert gas ions in the plasma. This can help increase a rate of sputtering. Further, the plasma can include both a lower-frequency radiofrequency power component and a higher-frequency radiofrequency power component. Using the lower-frequency component in addition to the higher-frequency radiofrequency component can help increase the kinetic energy of the inert gas ions in the plasma. This can increase a rate of sputtering. Further, the use of a longer duration of exposure to sputtering conditions also can be used to achieve more sputtering.

[0046] As a further example, showerhead temperature is another parameter that can be used to adjust sputtering conditions. For example, a lower showerhead temperature can lead to increased sputtering compared to a higher showerhead temperature in a PEALD process. Performing the process at a temperature of 650 °C or lower can help avoid seams and fin bending. A separation between a showerhead and the substrate support also can be controlled to adjust sputtering conditions. This is because the ion flux at the substrate surface can be dependent on the separation distance. In still further examples, the use of a powered substrate support and a grounded showerhead to form a capacitively coupled plasma can increase directional bias and enhance the sputtering effect compared to the use of a powered showerhead and grounded substrate support. In other examples, conditions other than the ones listed above can be controlled to adjust the sputtering effect on the substrate surface.

[0047] As mentioned above, the terms “high sputter” and “low sputter” are used below to describe the relative magnitudes of the sputtering effects in inhibition and deposition steps of an ALD cycle according to the present disclosure. These terms are relative to one another. For example, a “high sputter” inhibition step is more strongly sputtering than a “low sputter” inhibition step. Further, a “high sputter” deposition step is more strongly sputtering than a “low sputter” deposition step. Also, a “high sputter” deposition step is more strongly sputtering than a “low sputter” inhibition step. Additionally, a “high sputter” inhibition step is more strongly sputtering than a “low sputter” deposition step.

[0048] FIG. 3 shows a flow diagram for an example method 300 for performing a PEALD process to fill a gap on a substrate. Method 300 comprises performing a plurality of PEALD cycles 302. PEALD cycle 302 comprises an inhibition step 304 and a deposition step at 306. As described below, the inhibition step 304 can omitted from some PEALD cycles in a deposition process.

[0049] The inhibition step 304 comprises forming a plasma using a gas mixture comprising an inhibitor. Any suitable inhibitor can be used. Examples include hydrogen, nitrogen-containing inhibitors, fluorine-containing inhibitors, and carbon- containing inhibitors. Examples of nitrogen-containing inhibitors include nitrogen, ammonia, amines, diamines, and aminoalcohols. Examples of fluorine-containing inhibitors can include fluorine, nitrogen trifluoride, sulfur hexafluoride, hydrogen fluoride, xenon difluoride, and fluorocarbons such as tetrafluoromethane or hexafluoroethane. Examples of suitable carbon-containing inhibitors can include alkanes, alkenes, alkynes, cyclic hydrocarbons, aromatics, alcohols, aldehydes, esters, ethers, ketones, aldehydes, alkyl halides, alkyl amines, and alkyl diamines. The inhibition step 304 can be performed at any suitable conditions. Example pressures include pressures of 1 to 30 Torr. Example plasma conditions include radiofrequency power of 50 to 6000 W. Example frequencies for the radiofrequency plasma include frequencies of 400 kHz, 13.56 MHz, 27MHz, 60MHz, and 90MHz. 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 HF component can comprise frequencies of 3 MHz to 300 MHz. The LF component can comprise frequencies of 3 MHz and below. The plasma can be formed for any suitable duration. Examples include durations of 5 to 300 seconds. Further, the gas mixture used to form the plasma also can comprise one or more inert gases in addition to the inhibitor. Examples of inert gases include helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe).

[0050] The inhibition step 304 is performed under conditions configured to deposit the inhibitor into a gap on the substrate such that a concentration of inhibitor deposited at a first depth within the gap is greater than a concentration of the inhibitor deposited at a second depth within the gap. The second depth is deeper than the first depth.

[0051] FIGS. 4A-4E schematically show example structures formed during a PEALD gapfill process that includes inhibition steps and deposition steps. FIGS. 4A- 4E illustrate an example of method 300. First referring to FIG. 4A, substrate 400 comprises fins 402, 404, 406, 408. Substrate 400 can comprise any suitable material. Examples include silicon and / or germanium. Likewise, fins 402, 404, 406, 408 can comprise any suitable material. Fins 402, 404, 406, 408 define gaps 410, 412, 414.

[0052] Due to the spacing of fins 402, 404, 406, 408, gap 412 comprises a greater width than gaps 410 or 414. FIG. 4B schematically shows substrate 400 following an inhibition step, such as inhibition step 304. Substrate 400 is exposed to an inhibitor 420 to adsorb inhibitor onto the substrate. The inhibitor 420 is adsorbed under conditions configured to adsorb the inhibitor with a concentration gradient. For example, the concentration of inhibitor 420 adsorbed at a first depth 422 is greater than a concentration of inhibitor 420 adsorbed at a second depth 424.

[0053] The concentration gradient of the inhibitor on the sidewalls of fins 402, 404, 406, 408 can be controlled by controlling various processing conditions. Example processing conditions include total processing chamber pressure, partial pressure of the inhibitor, partial pressure of other gases (for example, a diluent gas), substrate temperature, gas flow rates, inhibitor gas flow duration, and plasma characteristics. For example, the use of a capacitively coupled plasma can cause directional effects that drive the inhibitor into a gap. Example frequencies for the radiofrequency plasma include frequencies of 400 kHz, 13.56 MHz, 27MHz, 60MHz, and 90MHz. In some examples, the capacitively coupled plasma can comprise a HF component and a LF component. Examples of frequencies for the HF component can comprise frequencies of 3 MHz to 300 MHz. In some examples, the HF component can comprise a power of 50 to 6000 W. Increasing the power of the higher frequency component can drive the inhibitor deeper within the gap. Further, in some examples, the LF component also can comprise a power of 0 to 5000 W. Examples of frequencies for the LF component can include frequencies of 3 MHz and below. The use of the LF component also can help drive the inhibitor deeper within the gap. Increasing the power of the LF component also can drive the inhibitor deeper within the gap. Thus, radiofrequency powers and frequencies can be adjusted to help deposit inhibitor 420 on deeper locations of fins 402, 404, 406, 408.

[0054] Returning to FIG. 3, method 300 further comprises, at 306, performing a deposition step. The deposition step comprises, at 308, exposing the substrate to a silicon-containing film precursor to adsorb silicon-containing film precursor on the substrate. Due to the inhibitor, a lesser concentration of the silicon-containing film precursor is adsorbed at the first depth than the second depth. Thus, the use of an inhibitor helps increase the growth rate of the silicon-containing film deeper on surfaces in the gap than on surfaces near the top of the gap. In some examples, a purge is performed after adsorbing the silicon-containing film precursor to the substrate.

[0055] Any suitable silicon-containing film precursor can be used. Example silicon-containing film precursors for forming silicon-containing films using PEALD can comprise materials having the general structure:where Ri, R2 and 3 can be the same or different substituents. In various examples, Ri, R2, and 3 can include silanes, siloxy groups, amines, halides, hydrogen, or organic groups such as alkylamines, alkoxy, alkyl, alkenyl, alkynyl, and cyclic groups (such as aromatic groups).

[0056] Example silicon-containing film precursors include silane, polysilanes (H3Si-(SiH2)n-SiH3), where n >0, such as disilane, trisilane, and tetrasilane, and trisilylamine.

[0057] In some examples, the silicon-containing film precursor is an alkoxysilane. Alkoxysilanes that can be used include compounds having a general formula of Hx-Si-(OR)y, where x = 1-3, x+y = 4 and each R is a substituted or unsubstituted aliphatic or aromatic group; and Hx(RO)y,-Si-Si-(OR)yHx, where each R is a substituted or unsubstituted aliphatic or aromatic group. Example alkoxysilanes include tetramethoxysilane (TMOS), diethoxymethylsilane (DEMS), diethoxysilane (DES), dimethoxymethylsilane, dimethoxysilane (DMOS), methyl-diethoxysilane (MDES), methyl-dimethoxysilane (MDMS), t-butoxy di silane, triethoxysilane (TES), and trimethoxysilane (TMS or TriMOS).

[0058] In some examples, the silicon-containing film precursor is a siloxane. Siloxanes include materials having Si-O-Si linkages. Example siloxanes include octamethylcyclotetrasiloxane (OMCTS), octamethoxydodecasiloxane (OMODDS), and tetramethylcyclotetrasiloxane (TMCTS).

[0059] In some examples, the silicon-containing film precursor is an aminosilane. Aminosilanes include materials having a general formula Hx-Si-(NR)y, where x = 1-3, x+y = 4, and R is a substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aromatic group, or hydride group. Example aminosilanes includebisdiethylaminosilane, diisopropylaminosilane, bis(t-butylamino) silane (BTBAS), di- sec-butylaminosilane, and tris(dimethylamino)silane (3DMAS).

[0060] In some examples, the silicon-containing film precursor is a halogencontaining silane. In some examples, a halogen-containing silane can comprise at least one hydrogen atom. Such a silane can have a general formula of SiXaHy where y > 1. Example halosilanes include dichlorosilane (EhSiCh), hexachlorodisilane (Si2Cle), and diiodosilane (H2SH2).

[0061] More specific examples of silicon-containing film precursors include polysilanes ((SinH2n+2, where n >1, such as silane, disilane, trisilane, and tetrasilane), trisilylamine, tetraethyl orthosilicate (TEOS), methylsilane, trimethylsilane (3MS), ethylsilane, butasilanes, pentasilanes, octasilanes, heptasilane, hexasilane, cyclobutasilane, cycloheptasilane, cyclohexasilane, cyclooctasilane, cyclopentasilane, l,4-dioxa-2,3,5,6-tetrasilacyclohexane, triethoxysiloxane (TRIES), and tetraoxymethylcyclotetrasiloxane (TOMCTS). In some examples, method 300 comprises optionally performing a purge after exposing the substrate to the silicon- containing precursor at 308.

[0062] Continuing, the deposition step 306 further comprises, at 310, forming a plasma comprising an oxidant to convert the silicon-containing film precursor into a silicon-containing film within the gap. Example films include silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, silicon oxycarbide, silicon carbonitride, and silicon oxycarbonitride. Examples of suitable plasma conditions are described above. In some examples, the plasma is formed using an oxidant comprising oxygen to form a silicon-containing film comprising oxygen. Example oxygen-containing oxidants include O2, N2O, and CO2. The use of N2O and / or CO2 can provide conditions that are less strongly oxidizing than O2. This can help avoid oxidation of Ge and / or other oxidation-susceptible substrate material(s). In some examples, O2 is used and N2O and CO2 are omitted. In some examples, H2 can be added to the plasma gas mixture to help provide less strongly oxidizing conditions compared to the use of O2 without H2. An example precursor for providing nitrogen for formation of a silicon oxynitride film is N2O. An example precursor for providing nitrogen for the formation of a nitride film is molecular nitrogen (N2). Further, in some examples, method 300 comprises performing a purge after forming the plasma comprising the oxidant at 310.

[0063] Method 300 further comprises, at 320, determining whether to perform additional PEALD cycles 302. If additional PEALD cycles are to be performed, method 300 returns to 302 and performs another PEALD cycle. Any suitable number of PEALD cycles 302 can be performed during processing of a substrate. Further, in some examples, method 300 can comprise performing a PEALD cycle that omits performing inhibition step 304. For example, at 322, method 300 determines whether to perform a deposition step 306 without an inhibition step 304. If “YES”, method 300 can perform a PEALD cycle 302 that omits inhibition step 304. In this manner, inhibition can be performed with any suitable frequency. On the other hand, if it is determined at 320 not to perform additional PEALD cycles, the method 300 terminates at 324.

[0064] As mentioned above, the PEALD cycle 302 comprises performing an inhibition step and / or a deposition step under high sputter conditions to avoid formation of a seam in the silicon-containing film within the gap. This also can help to avoid uneven gapfill and resulting spacer displacement. As mentioned above, high sputter conditions can comprise use of a relatively lower pressure, a relatively higher radiofrequency power, a relatively longer plasma duration, a relatively heavier inert gas, a relatively lower showerhead temperature, or a combination of two or more of such conditions, compared to low sputter conditions.

[0065] Continuing, at 334, method 300 optionally comprises using plasma conditions configured to sputter the silicon-containing film during an inhibition step. The plasma conditions at 334 can comprise, for example, forming a plasma using a gas mixture comprising the inhibitor and one or more of nitrogen and an inert gas. In some examples, nitrogen is used both as an inhibitor and as a sputter gas. Any suitable inert gas can be used. Use of a heavier inert gas, such as Ar, Kr, or Xe, can provide for a higher rate of sputtering than a lighter inert gas, such as He or Ne, under otherwise similar conditions. In some examples, inhibition step 334 comprises using a pressure of 4.5 Torr or lower. Alternatively or additionally, in some examples, inhibition step 334 comprises using a radiofrequency power of 1000 W to 6000 W to form the plasma. In other examples, even lower powers can be used, depending upon parameters such as processing chamber pressure, gas composition, the distance of the gap between the showerhead and pedestal, etc. In some examples, alternatively or additionally, inhibition step 334 comprises a duration of 40 seconds or longer. In some examples, inhibition step 334 comprises a combination of these processing conditions. In contrast, an inhibition step 304 that is not configured for sputtering the silicon-containing filmcan comprise a relatively higher pressure, a relatively lower radiofrequency power, and a relatively shorter duration, compared to the ranges above. Examples include pressures of 5 Torr or greater, radiofrequency powers of 2000 W or less, and durations of 30 seconds or less.

[0066] Alternatively or additionally, at 336, method 300 optionally comprises performing a high sputter deposition step using plasma conditions configured to sputter the silicon-containing film during the oxidation portion of the ALD. Deposition step 336 comprises forming a plasma using a gas mixture comprising one or more of an oxidant, nitrogen, and an inert gas. As mentioned above, suitable oxidants include O2, N2O, and CO2. Use of a heavier inert gas, such as Ar, can provide a higher sputtering rate than a lighter inert gas such as He or Ne. In some examples, deposition step 336 comprises using a pressure of 2.0 Torr or lower. In contrast, a deposition step 306 that is not configured for sputtering the silicon-containing film can comprise a relatively higher pressure, such as a pressure of 5.0 Torr or greater. Example frequencies for the radiofrequency plasma include frequencies of 400 kHz, 13.56 MHz, 27MHz, 60MHz, and 90MHz. Examples of frequencies for a HF component include frequencies of 3 MHz to 300 MHz. Examples of frequencies for a LF component can include frequencies of 3 MHz and below. Any suitable radiofrequency power can be used. Examples include HF radiofrequency power of 50 to 6000 W and LF radiofrequency power of 0 to 5000 W. In some more specific examples, the deposition step 336 can be performed using HF radiofrequency power of 1000 to 6000 W and LF radiofrequency power of 1000 to 3000 W.

[0067] FIG. 4C shows substrate 400 following an arbitrary number of PEALD cycles (e.g., PEALD cycles 302). A silicon-containing film 430 partially fills gaps 410, 412, 414. Silicon-containing film 430 can comprise any suitable material. Examples include silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, silicon oxycarbide, silicon carbonitride, and silicon oxycarbonitride. As mentioned above, inhibition and sputtering help to grow a film with a V-shaped profile from the bottom up to avoid seam formation. Further, sputtering in combination with inhibition has a net effect of more even film growth in gaps having different widths. This helps to avoid fin displacement. In some examples, the PEALD cycles comprise performing an inhibition step under plasma conditions that are configured to sputter a portion of the silicon- containing film material. Alternatively or additionally, in some examples, the PEALD cycles comprise performing a deposition step under plasma conditions that areconfigured to sputter a portion of the silicon-containing film material. The plasma conditions can sputter material from the first depth 422 within the gap and redeposit at least some of the portion of the silicon-containing film material at the second depth 424 within the gap. Due to the use of processing conditions configured to sputter the silicon- containing film, gaps 410, 412, 414 are filled relatively evenly. Further, due to the inhibitor 420, the silicon-containing film 430 grows with a V-shaped profile.

[0068] FIG. 4D shows substrate 400 following another inhibition step. As a result of the inhibition step, inhibitor 420 is absorbed onto substrate 400 with a concentration gradient where a concentration of inhibitor adsorbed at a first depth within the gap is greater than a concentration of inhibitor adsorbed at a second, deeper depth within the gap. Performing inhibition steps during PEALD processing helps slow film growth near the top of the gap such that the silicon-containing film 430 grows with a V-shaped profile and fills the gap in a bottom-up manner.

[0069] FIG. 4E shows substrate 400 following additional PEALD cycles to completely fill gaps 410, 412, 414. Due to the V-shaped growth profile, the gaps 410, 412, 414 are filled without seams. This helps avoid blowout if the substrate is etched in later processing steps. Further, due to the use of inhibition steps and sputtering during PEALD processing, gaps 410, 412, 414 are filled relatively evenly. This helps avoid the zippering effect that can pull fins together. In contrast to the structure shown in FIG. 2C, fins 402, 404, 406, 408 of FIG. 4E are not displaced. In some examples, the fins each deflect less than 0.5 nm from vertical as measured at the tops of the fins. For example, distance 432 represents the distance between the top of fin 404 and the top of fin 406. If, for example, fin 404 and fin 406 each deflect 0.5 nm or less towards each other, distance 432 can change by less than 1 nm in such examples. In some examples, deflection of a fin can depend on the aspect ratio of the fin and / or the aspect ratio of a gap between fins. In some examples, where the aspect ratio is 5: 1 or greater, the examples disclosed herein still can be used to fill a gap with fins that deflect less than 0.5 nm from vertical.

[0070] FIG. 5 shows a flow diagram of an example method 500 for processing a substrate comprising a gap. Method 500 can be performed in a processing chamber of a processing tool configured for PEALD. An example processing tool is described below with regard to FIG. 6.

[0071] At 502, method 500 comprises performing a plurality of PEALD cycles to deposit a silicon-containing film into a gap on a substrate. Any suitable material canbe used. Examples include silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, silicon oxycarbide, silicon carbonitride, and silicon oxycarbonitride. In some examples, the substrate comprises Si, Ge, SiGe, or a combination thereof.

[0072] In some examples, at 503, method 500 comprises heating the substrate to a temperature of 50 °C to 650 °C. In some such examples, the substrate is heated to a temperature of 600 °C or less. In some such examples, the substrate is heated to a temperature of 500 °C or less. As discussed above, performing the PEALD cycles at a temperature < 650 °C helps to avoid seams and fin bending. Further, performing the PEALD cycles at a temperature < 600 °C also helps to avoid diffusion and oxidation of Ge or other substrate materials.

[0073] At 504, method 500 comprises, in an inhibition step, forming a plasma using a gas mixture comprising an inhibitor to expose the substrate to the inhibitor. Step 504 is performed under conditions configured to deposit inhibitor into the gap such that a concentration of the inhibitor deposited at a first depth within the gap is greater than a concentration of the inhibitor deposited at a second depth within the gap, the second depth being deeper in the gap than the first depth. Any suitable inhibitor can be used. In some examples, the inhibitor comprises one or more of nitrogen, hydrogen, ammonia, or nitrogen trifluoride. The plasma can be formed using any suitable plasma conditions. Example frequencies for the radiofrequency plasma include frequencies of 400 kHz, 13.56 MHz, 27MHz, 60MHz, and 90MHz. Examples include radiofrequency power of 50 to 6000 W.

[0074] At 508, method 500 comprises, in a deposition step, exposing the substrate to a silicon-containing film precursor to adsorb silicon-containing film precursor on the substrate. Here, the inhibitor causes a lesser concentration of the silicon-containing film precursor to adsorb at the first depth than at the second depth. Any suitable silicon-containing film precursor can be used, such as those listed above. An example precursor for providing nitrogen for formation of a silicon oxynitride film is N2O. Examples of oxidants for facilitating formation of the silicon-containing film include O2, N2O, and CO2. In some examples, method 500 is performed under conditions to avoid oxidation of Ge in the substrate. As described above, the use of N2O and / or CO2 can provide for less strongly oxidizing conditions in the processing chamber compared to the use of O2 to help avoid oxidation of substrate material. Thus, in some examples, the amount of N2O or CO2 used is greater than an amount of O2 used. Insome examples, no O2 is used. Likewise, in some examples, O2 is used and N2O and CO2 are omitted. Further, in some examples, H2 is added to the plasma gas mixture. Using H2 also can help avoid oxidation of Ge in examples where the substrate comprises Ge. As discussed above, performing the PEALD cycles at a temperature below 650 °C (e.g., at step 503) helps to avoid seams and fin bending. Performing the PEALD cycles at a temperature < 600 °C also helps to avoid diffusion and oxidation of Ge or other substrate materials.

[0075] Continuing, at 510, method 500 comprises purging the processing chamber after adsorbing the silicon-containing film precursor on the substrate.

[0076] At 512, method 500 comprises forming a plasma to convert the silicon- containing film precursor into a silicon-containing film within the gap. Example frequencies for the radiofrequency plasma include frequencies of 400 kHz, 13.56 MHz, 27MHz, 60MHz, and 90MHz. Examples of frequencies for a HF component include frequencies of 3 MHz to 300 MHz. Examples of frequencies for a LF component can include frequencies of 3 MHz and below. Any suitable radiofrequency power can be used. Examples include HF radiofrequency power of 50 to 6000 W and LF radiofrequency power of 0 to 5000 W. In some more specific examples, method 500 can comprise performing the deposition step using HF radiofrequency power of 1000 to 6000 W and LF radiofrequency power of 1000 to 3000 W. At 514, method 500 comprises purging the processing chamber after forming the plasma.

[0077] Method 500 further comprises, at 516, in at least one of the inhibition step or the deposition step, exposing the substrate to a plasma comprising one or more of the inhibitor, an oxidant, nitrogen, or an inert gas and under plasma conditions configured to sputter the silicon-containing film. This helps to avoid uneven gapfill by sputtering film material from higher portions of gaps. Sputtering also helps to avoid formation of a seam in the silicon-containing film within the gap by causing gaps to fill in a bottom-up manner, as shown in FIGS. 4A-4E, rather than by conformal growth.

[0078] In some examples, a PEALD cycle can comprise performing an inhibition step with high sputter conditions and performing a deposition step with low sputter conditions. In some such examples, method 500 comprises, in an inhibition step, forming a plasma using a gas mixture comprising a relatively heavier inert gas (e.g. Ar) and an inhibitor, such as N2. In some such examples, method 500 comprises performing the inhibition step at a pressure of 4.5 Torr or lower. In some such examples, method500 alternatively or additionally comprises performing the inhibition step using a radiofrequency power of 1000 W or greater to form the plasma. In some examples, method 500 alternatively or additionally comprises performing the inhibition step for a duration of 40 seconds or longer. In some such examples, method 500 comprises performing the deposition step at a pressure of 5.0 Torr or greater.

[0079] Alternatively or additionally, in some examples, a PEALD cycle can comprise performing an inhibition step with low sputter conditions and performing a deposition step with high sputter conditions. In some such examples, method 500 comprises, in the deposition step, forming the plasma using a gas mixture comprising one or more of nitrogen or an inert gas. In some such examples, method 500 comprises performing the deposition step at a pressure of 2.0 Torr or lower. In some such examples, method 500 comprises, performing the inhibition step using a pressure of 5.0 Torr or greater, a radiofrequency power of 2000 W or less, and a duration of 30 seconds or less. In some examples, the deposition step can be performed at a pressure that is equal to or greater than a pressure of the inhibition step.

[0080] In still further examples, a PEALD cycle can comprise performing an inhibition step with high sputter conditions and performing a deposition step with high sputter conditions. Continuing, at 520, method 500 optionally comprises performing a PEALD cycle that omits the inhibition step.

[0081] FIG. 6 schematically shows an example processing tool 600 that can implement the examples described above with reference to FIGS. 3-5. 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 50 °C to 650 °C.

[0082] 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 sili con-containing film precursor source 616, an oxidant source 618, an inhibitor source 620, optionally anitrogen 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.

[0083] The silicon-containing film precursor source 616 comprises any suitable precursor chemical(s) for forming a silicon-containing film. Examples silicon- containing films include films comprising silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, silicon oxycarbide, silicon carbonitride, and silicon oxycarbonitride. Examples of silicon-containing film 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.

[0084] Optionally, a carbon-containing precursor source (not shown) can be used to provide a carbon-containing precursor for forming a silicon carbide film. Example carbon-containing precursors include those listed above. Further, in some examples, an optional oxidant source 618 can be used to provide an oxidant for forming silicon oxide, silicon oxynitride, silicon oxycarbide, or silicon oxycarbonitride films. Examples of oxidants can include molecular oxygen, water, hydrogen peroxide, ozone, and nitrogen oxides. Optionally, a hydrogen source (not shown) can be included to provide hydrogen. In some examples, hydrogen can be used in a plasma used in a deposition step to help film formation. For example, EE also can help provide less strongly oxidizing conditions within the processing chamber 602 than in the absence of hydrogen.

[0085] The inhibitor source 620 can comprise any suitable inhibitor. Examples include hydrogen, nitrogen-containing inhibitors such as nitrogen or ammonia, fluorine-containing inhibitors such as nitrogen trifluoride, carbon-containing inhibitors, and mixtures thereof.

[0086] Optional nitrogen source 622 comprises nitrogen (N2). In examples where inhibitor source 620 comprises nitrogen, the nitrogen source 622 can be omitted.

[0087] The inert gas source 624 can comprise any suitable inert gas. Examples include argon, helium, neon, krypton, and xenon. In some examples, using a heavier inert gas, such as Ar, Kr, or Xe, can help increase sputtering of the silicon-containing film compared to use of a lighter inert gas, such as He or Ne.

[0088] 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.

[0089] The processing tool 600 further comprises a radiofrequency power source 634 that is electrically connected to showerhead 610. Radiofrequency power source 634 is configured to form a plasma using a gas mixture.

[0090] For example, during an inhibition step, radiofrequency power source 634 can be operated to form a plasma using a gas mixture comprising an inhibitor. Additionally, 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 and an inert gas to deposit a silicon-containing film. Additionally, radiofrequency power source 634 also is configured to form a plasma to sputter a film. For example, the radiofrequency power source 634 can be configured to provide greater radiofrequency power for high sputter conditions than for low sputter conditions. The substrate support 604 is configured as a grounded opposing electrode in this example. In other examples, the radiofrequency power source 634 can supply radiofrequency power to substrate support 604, or to another suitable electrode structure. In such examples, supplying radiofrequency power to substrate support 604 can increase plasma bias and directionality. This can help increase sputtering of the silicon- containing film. Thus, the radiofrequency power source 634 forms a capacitively coupled plasma (CCP) when operated. 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.

[0091] The processing tool 600 further includes include a matching network 636 for impedance matching of the radiofrequency power source 634. Theradiofrequency 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 different 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 0 to 5000 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 50 to 6000 W, in some examples.

[0092] 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. The controller 650 is configured to control various functions of processing tool 600 to perform PEALD cycles including inhibition steps and deposition steps. For example, the controller 650 is configured to control processing tool 600 to perform high sputter inhibition steps and / or high sputter deposition steps, as well as low sputter inhibition steps and / or low sputter deposition steps. For example, the controller 650 is configured to operate the substrate heater 608 to heat a substrate to a desired temperature. Examples include temperatures of 50 °C to 650 °C. The controller 650 also is configured to operate the flow control hardware 612 to flow a selected gas or mixture of gases at a selected rate into the processing chamber 602. The controller 650 is further configured to operate the exhaust system 632 to remove gases from processing chamber 602. The controller 650 can, for example, control the exhaust system 632 and / or the flow control hardware 612 to purge the processing chamber 602. The controller 650 is configured to operate the radiofrequency power source 634 to form a plasma, as well as to control any other suitable functions of processing tool 600. The controller 650 can comprise any suitable computing system. Example computing systems are described below with reference to FIG. 7.

[0093] Thus, by performing sputtering during a PEALD process, gaps between fins can be filled more evenly. By avoiding uneven gapfill, a PEALD process with sputtering can help avoid fin displacement. Additionally, seam formation can be avoided by performing inhibition and sputtering during a PEALD gapfill process.Further, by performing the PEALD cycles at temperatures < 650 °C, the disclosed examples help avoid fin displacement. By performing the PEALD cycles at temperatures < 600 °C, the disclosed examples also help avoid thermal oxidation and Ge diffusion.

[0094] 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 can take the form of one or more personal computers, workstations, computers integrated with substrate processing tools, and / or network accessible server computers.

[0095] Computing system 700 includes a logic machine 702 and a storage machine 704. Computing system 700 can 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.

[0096] Logic machine 702 includes one or more physical devices configured to execute instructions. For example, the logic machine 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.

[0097] The logic machine can include one or more processors configured to execute software instructions. Additionally or alternatively, the logic machine can include one or more hardware or firmware logic machines configured to execute hardware or firmware instructions. Processors of the logic machine can be single-core or multi-core, and the instructions executed thereon can be configured for sequential, parallel, and / or distributed processing. Individual components of the logic machine 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 machine can be virtualized and executed by remotely accessible, networked computing devices configured in a cloud-computing configuration.

[0098] Storage machine 704 includes one or more physical devices configured to hold instructions 712 executable by the logic machine to implement the methods andprocesses described herein. When such methods and processes are implemented, the state of storage machine 704 can be transformed — e.g., to hold different data.

[0099] Storage machine 704 can include removable and / or built-in devices. Storage machine 704 can include optical memory (e.g., CD, DVD, HD-DVD, Blu-Ray Disc, etc.), semiconductor memory (e.g., RAM, EPROM, EEPROM, etc.), and / or magnetic memory (e.g., hard-disk drive, floppy-disk drive, tape drive, MRAM, etc.), among others. Storage machine 704 can include volatile, nonvolatile, dynamic, static, read / write, read-only, random-access, sequential-access, location-addressable, file- addressable, and / or content-addressable devices.

[0100] It will be appreciated that storage machine 704 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.

[0101] Aspects of logic machine 702 and storage machine 704 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.

[0102] When included, display subsystem 706 can be used to present a visual representation of data held by storage machine 704. 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 706 can likewise be transformed to visually represent changes in the underlying data. Display subsystem 706 can include one or more display devices utilizing virtually any type of technology. Such display devices can be combined with logic machine 702 and / or storage machine 704 in a shared enclosure, or such display devices can be peripheral display devices.

[0103] When included, input subsystem 708 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 voicerecognition, and an infrared, color, stereoscopic, and / or depth camera for machine vision and / or gesture recognition.

[0104] When included, communication subsystem 710 can be configured to communicatively couple computing system 700 with one or more other computing devices. Communication subsystem 710 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 700 to send and / or receive messages to and / or from other devices via a network such as the Internet.

[0105] 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.

[0106] 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 processing a substrate comprising a gap, the method comprising: performing a plurality of plasma-enhanced atomic layer deposition (PEALD) cycles to deposit a silicon-containing film into the gap, a PEALD cycle of the plurality of PEALD cycles comprising in an inhibition step, forming a plasma using a gas mixture comprising an inhibitor to expose the substrate to the inhibitor under conditions configured to deposit the inhibitor into the gap such that a concentration of the inhibitor deposited at a first depth within the gap is greater than a concentration of the inhibitor deposited at a second depth within the gap, the second depth being deeper in the gap than the first depth; and in a deposition step, adsorbing a silicon-containing film precursor to the substrate, the inhibitor causing a lesser concentration of the silicon-containing film precursor to adsorb at the first depth than at the second depth, and forming a plasma to convert the silicon-containing film precursor adsorbed to the substrate into a silicon-containing film within the gap, wherein at least one of the inhibition step or the deposition step comprises exposing the substrate to a plasma under conditions configured to sputter the silicon-containing film.

2. The method of claim 1, wherein the plasma conditions are configured to sputter a portion of the silicon-containing film material from the first depth within the gap and redeposit at least some of the portion of the silicon-containing film material at the second depth within the gap.

3. The method of claim 1, wherein the inhibition step is performed at a first pressure of 5 Torr or lower, and the deposition step is performed at a second pressure equal to or greater than the first pressure.

4. The method of claim 1, wherein the deposition step is performed at a first pressure of 2 Torr or lower, and the inhibition step is performed at a second pressure of 5 Torr or greater.

5. The method of claim 1, wherein the plasma conditions configured to sputter the silicon-containing film include a plasma formed using a radiofrequency power of 1000 W to 6000 W.

6. The method of claim 1, wherein the method comprises heating a substrate to a temperature of 50 to 650 °C.

7. The method of claim 1, wherein the substrate comprises a first fin and a second fin with the gap disposed therebetween, and the first fin and the second fin each deflect less than 0.5 nm from vertical as measured at a top of the first fin and a top of the second fin upon completion of depositing the silicon-containing film into the gap.

8. The method of claim 1, wherein the substrate comprises silicon and germanium, and the deposition step is performed under conditions configured to avoid oxidization of the germanium.

9. The method of claim 1, wherein the silicon-containing film comprises one of silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, silicon oxycarbide, silicon carbonitride, or silicon oxycarbonitride.

10. The method of claim 1, wherein the inhibitor comprises one or more of nitrogen, hydrogen, ammonia, or nitrogen trifluoride.

11. The method of claim 1, wherein forming the plasma to convert the silicon- containing film precursor into a silicon-containing film comprises forming a plasma using an oxidant comprising one or more of nitrous oxide or carbon dioxide at a concentration that is greater than a concentration of oxygen.

12. The method of claim 1, wherein a PEALD cycle of the plurality of PEALD cycles omits the inhibition step.

13. An atomic layer deposition (ALD) tool, comprising: a processing chamber; a substrate support disposed in the processing chamber;flow control hardware configured to control flow of gas from an inhibitor source, a silicon-containing film precursor source, and an inert gas source into the processing chamber; a radiofrequency power source configured to form a plasma in the processing chamber; and a controller configured to control the ALD tool to in an inhibition step, operate the flow control hardware to flow the inhibitor into the processing chamber, and operate the radiofrequency power source to form a plasma under conditions configured to deposit inhibitor within a gap on a substrate such that a concentration of the inhibitor deposited at a first depth within the gap is greater than a concentration of the inhibitor deposited at a second depth within the gap, the second depth being deeper in the gap than the first depth; in a deposition step, operate the flow control hardware to flow the silicon-containing film precursor to the processing chamber to adsorb the silicon-containing film precursor on the substrate, and operate the radiofrequency power source form a plasma to oxidize the film precursor to form a layer of an oxide film; and in one or more of the inhibition step or the deposition step, operate the flow control hardware and the radiofrequency power source to form a plasma using one or more of the inhibitor, an oxidant, nitrogen, or an inert gas under conditions configured to sputter the silicon-containing film.

14. The ALD tool of claim 13, wherein the controller is configured to, in the inhibition step, operate the flow control hardware to form a first pressure in the processing chamber of 5 Torr or lower, and, in the deposition step, operate the flow control hardware to form a second pressure in the processing chamber equal to or greater than the first pressure.

15. The ALD tool of claim 13, wherein the controller is configured to, in the inhibition step, operate the flow control hardware to form a first pressure in the processing chamber of 5 Torr or greater, and, in the deposition step, operate the flowcontrol hardware to form a second pressure in the processing chamber of 2 Torr or lower.

16. The ALD tool of claim 13, further comprising the inhibitor source comprising the inhibitor, the inhibitor comprising one or more of nitrogen, hydrogen, ammonia, or nitrogen trifluoride.

17. A method of processing a substrate comprising a gap, the method comprising: heating the substrate to a temperature of 650 °C or lower; performing a plurality of plasma-enhanced atomic layer deposition (PEALD) cycles while heating the substrate to deposit a silicon-containing film into the gap, a PEALD cycle of the plurality of PEALD cycles comprising in an inhibition step, forming a plasma using a gas mixture comprising an inhibitor to expose the substrate to the inhibitor under conditions configured to deposit inhibitor into the gap such that a concentration of the inhibitor deposited at a first depth within the gap is greater than a concentration of the inhibitor deposited at a second depth within the gap, the second depth being deeper in the gap than the first depth; and in a deposition step, exposing the substrate to a silicon-containing film precursor to adsorb silicon-containing film precursor on the substrate, the inhibitor causing a lesser concentration of the silicon-containing film precursor to adsorb at the first depth than at the second depth, and forming a plasma to convert the silicon-containing film precursor into a silicon-containing film within the gap, wherein at least one of the inhibition step or the deposition step comprises exposing the substrate to a plasma comprising one or more of the inhibitor, an oxidant, nitrogen, or an inert gas under plasma conditions configured to sputter the silicon-containing film as the silicon-containing film grows to avoid formation of a seam in the silicon-containing film within the gap.

18. The method of claim 17, wherein the inhibition step is performed at a first pressure of 5 Torr or lower, and the deposition step is performed at a second pressure equal to or greater than the first pressure.

19. The method of claim 17, wherein the deposition step is performed at a first pressure of 2 Torr or lower, and the inhibition step is performed at a second pressure of 5 Torr or greater.

20. The method of claim 17, wherein the substrate comprises a first fin and a second fin with the gap disposed therebetween, and the first fin and the second fin each deflect less than 0.5 nm from vertical as measured at a top of the first fin and a top of the second fin upon completion of depositing the silicon-containing film into the gap.

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