SEAM-free gapfill of dielectric films

Abstract

Examples are disclosed that relate to processes for seam-free gapfill of dielectric films. One disclosed example provides a method comprising depositing an inhibitor on the substrate under conditions such that a first concentration of the inhibitor deposited at a first depth within the gap is greater than a second concentration of the inhibitor deposited at a second depth within the gap, wherein the second depth is deeper within the gap than the first depth. The method further comprises performing a plurality of deposition cycles. Each deposition cycle comprises exposing the substrate to an aluminum-containing precursor and reacting adsorbed aluminum-containing precursor with an oxygen-containing reactant to form a layer of the aluminum oxide film.

Description

Docket No. LRC24321PPCTSEAM-FREE GAPFILL OF DIELECTRIC FILMSBACKGROUND

[0001] Electronic device fabrication processes can involve many steps of material deposition, patterning, and removal to form integrated circuits on a substrate. Various methods can be used to deposit films of materials onto a substrate. For example, atomic layer deposition (ALD) can be used to deposit 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. 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] One disclosed example provides a method of filling a gap on a substrate. The method comprises depositing an inhibitor on the substrate under conditions such that a first concentration of the inhibitor deposited at a first depth within the gap is greater than a second concentration of the inhibitor deposited at a second depth within the gap, wherein the second depth is deeper within the gap than the first depth. The method further comprises performing a plurality of deposition cycles. Each deposition cycle comprises exposing the substrate to an aluminum-containing precursor and reacting adsorbed aluminum-containing precursor with an oxygen-containing reactant to form a layer of the aluminum oxide film.

[0004] In some such examples, the method further comprises redepositing the inhibitor between at least two deposition cycles of the plurality of deposition cycles.

[0005] Additionally or alternatively, in some such examples, the method further comprises using a plasma to deposit the inhibitor.Docket No. LRC24321PPCT

[0006] Additionally or alternatively, in some such examples, the inhibitor comprises one or more of a nitrogen-containing compound, a halogen-containing compound, or a carbon-containing compound.

[0007] Additionally or alternatively, in some such examples, the inhibitor comprises one or more of nitrogen (N2), ammonia (NH3), an amine, a diamine, or an aminoalcohol.

[0008] Additionally or alternatively, in some such examples, the method further comprises using thermal energy in the absence of a plasma to react the adsorbed aluminum-containing precursor with the oxygen-containing precursor.

[0009] Additionally or alternatively, in some such examples, the oxygencontaining reactant comprises one or more of molecular oxygen, a nitrogen oxide, a carbon oxide, ozone, water vapor, or an alcohol.

[0010] Additionally or alternatively, in some such examples, the plurality of deposition cycles are performed at a substrate holder temperature within a range of 250 and 650 degrees Celsius.

[0011] Additionally or alternatively, in some such examples, the aluminum- containing precursor comprises organoaluminum compound with a vapor pressure within a range of 1 to 12 torr at 25 degrees Celsius.

[0012] Additionally or alternatively, in some such examples, the aluminum- containing precursor comprises one or more of dimethyl aluminum isopropoxide, dimethyl aluminum ethoxide, or dimethyl aluminum methoxide.

[0013] Additionally or alternatively, in some such examples, the gap is a horizontal trench in a gate-all-around field effect transistor (GAAFET) device.

[0014] Another example provides a method of filling a gap on a substrate. The method comprises depositing an inhibitor on the substrate under conditions such that a first concentration of the inhibitor deposited at a first depth within the gap is greater than a second concentration of the inhibitor deposited at a second depth within the gap, wherein the second depth is deeper within the gap than the first depth. The method further comprises performing a plurality of thermal CVD process deposition cycles. Each deposition cycle further comprises exposing the substrate to an aluminum- containing precursor. The aluminum-containing precursor comprises an organoaluminum compound. Each deposition cycle further comprises thermally reacting adsorbed aluminum-containing precursor with an oxygen-containing reactant in the absence of a plasma to form a layer of the aluminum oxide film.Docket No. LRC24321PPCT

[0015] In some such examples, the inhibitor comprises one or more of nitrogen (N2), ammonia (NH3), an amine, a diamine, or an aminoalcohol.

[0016] Additionally or alternatively, in some such examples, the method further comprises using a plasma to deposit the inhibitor under conditions 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, deeper depth within the gap.

[0017] Additionally or alternatively, in some such examples, the organoaluminum compound comprises one or more of dimethyl aluminum isopropoxide, dimethyl aluminum ethoxide, or dimethyl aluminum methoxide.

[0018] Another example provides a processing tool. The processing tool comprises a processing chamber. The processing tool further comprises a substrate holder in the processing chamber. The processing tool further comprises a substrate heater configured to heat a substrate positioned on the substrate holder. 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 power source configured to form a plasma in the processing chamber for processing substrates. The processing tool is configured to cause deposition of an inhibitor on a substrate under conditions such that a first concentration of the inhibitor deposited at a first depth within the gap is greater than a second concentration of the inhibitor deposited at a second depth within the gap, wherein the second depth is deeper within the gap than the first depth. The deposition tool is further configured to perform a plurality of deposition cycles. Each deposition cycle comprises exposing the substrate to an aluminum-containing precursor, and reacting adsorbed aluminum-containing precursor with an oxygen-containing reactant to form a layer of an aluminum oxide film.

[0019] In some such examples, the deposition tool is configured to executable to redeposit the inhibitor between at least two deposition cycles of the plurality of deposition cycles.

[0020] Additionally or alternatively, in some such examples, the inhibitor comprises one or more of nitrogen (N2), ammonia (NH3), an amine, a diamine, or an aminoalcohol.Docket No. LRC24321PPCT

[0021] Additionally or alternatively, in some such examples, the aluminum- containing precursor comprises one or more of dimethyl aluminum isopropoxide, dimethyl aluminum ethoxide, or dimethyl aluminum methoxide.

[0022] Additionally or alternatively, in some such examples, the oxygencontaining reactant comprises one or more of molecular oxygen, a nitrogen oxide, a carbon oxide, ozone, water vapor, or an alcohol.

[0023] Another example provides a method of depositing an aluminum oxide film comprising a varied density within a gap on a substrate. The method comprises performing a first set of one or more deposition cycles with a first set of deposition parameters to form a first portion of the aluminum oxide film with a first density. The method further comprises performing a second set of one or more deposition cycles with a second set of deposition parameters to form a second portion of the aluminum oxide film with a second density.

[0024] In some such examples, the first set of deposition parameters comprises a first temperature and the second set of deposition parameters comprises a second temperature.

[0025] Additionally or alternatively, in some examples, the first set of deposition parameters comprises a first aluminum-containing precursor exposure time, and the second set of deposition parameters comprises a second d aluminum-containing precursor exposure time.

[0026] Additionally or alternatively, in some examples, the first set of deposition parameters comprises a first reactant exposure time and the second set of deposition parameters comprises a second reactant exposure time.

[0027] Additionally or alternatively, in some examples, the second portion of the aluminum oxide film is a seam portion of the aluminum oxide gapfill film, wherein the second density is higher than the first density.

[0028] Additionally or alternatively, in some examples, the method further comprises depositing an inhibitor on the substrate under conditions such that a first concentration of the inhibitor deposited at a first depth within the gap is greater than a second concentration of the inhibitor deposited at a second depth within the gap, wherein the second depth is deeper within the gap than the first depth.Docket No. LRC24321PPCTBRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIGS. 1A-1C schematically show seam formation in an example substrate comprising horizontal gaps during an aluminum oxide gapfill process.

[0030] FIGS. 2A-2B schematically show void formation in a reentrant horizontal gap of an example substrate during an aluminum oxide gapfill process.

[0031] FIGS. 3A-3C schematically show seam formation in an example substrate comprising a vertical gap during an aluminum oxide gapfill process.

[0032] FIGS. 4A-4C schematically show void formation in an example substrate comprising a reentrant vertical gap during an aluminum oxide gapfill process.

[0033] FIG. 5 shows an example plot of a mean thickness of an aluminum oxide film as a function of exposure time.

[0034] FIG. 6 shows a flow diagram of an example method for performing seamless aluminum oxide ALD gapfill.

[0035] FIGS. 7A-7F schematically show structures formed in an example aluminum oxide gapfill process to fill horizontal gaps.

[0036] FIGS. 8A-8F schematically show structures formed in an example aluminum oxide gapfill process to fill a vertical gap.

[0037] FIGS. 9A-9C schematically show seam failure in an example substrate comprising horizontal gaps during recess etching of an aluminum oxide gapfill film.

[0038] FIGS. 10A-10D schematically show structures formed in an example aluminum oxide gapfill film deposition process to fill gaps in a substrate comprising horizontal gaps.

[0039] FIG. 11 schematically shows an example processing tool that can be used to perform an inhibited aluminum oxide gapfill process.

[0040] FIG. 12 schematically shows an example computing system.DETAILED DESCRIPTION

[0041] The term “aspect ratio” may generally represent a ratio of a depth of a substrate feature, such as a gap, to a width of the feature (for example, an average width).

[0042] The term “atomic layer deposition” (ALD) may generally represent a process in which a film is formed on a substrate in one or more individual layers by cyclically adsorbing a precursor to the substrate and reacting the adsorbed precursor to form a film layer. Plasma-enhanced ALD (PEALD) utilizes a plasma to facilitate aDocket No. LRC24321PPCT chemical conversion of adsorbed precursor to a film layer. Thermal ALD (TALD) utilizes thermal energy to facilitate conversion of adsorbed precursor to a film layer. The terms “growth”, “deposition”, and variants thereof, also can be used to refer to film formation.

[0043] The term “carbon-containing inhibitor” may generally represent any material that can be introduced into a processing chamber in a gas phase to deposit carbon as an inhibitor on a substrate. Examples of carbon-containing precursors include alkanes, alkenes, alkynes, cyclic hydrocarbons, aromatics, alcohols, diols, aldehydes, esters, ethers, ketones, alkyl amines, alkyl diamines, and organosilicon compounds. Examples of suitable alkanes include alkanes having a general formula of CnH2n+2 in which n = 1 to 10. More particular example alkanes may include methane, ethane, propane, and butane. Examples of suitable alkenes include alkenes having a general formula of CnEbn, in which n = 2 to 10 for an alkene with a single carbon-carbon double bond). More particular example alkenes may include ethene, propene, and butene. Examples of suitable alkynes include alkynes having a general formula of CnH2n-2, in which n = 2 to 10, for an alkyne with a single carbon-carbon triple bond. More particular example alkynes may include acetylene, propyne, and butyne. Examples of suitable cyclic hydrocarbons may include cyclobutane, cyclopentane, and cyclohexane. Examples of suitable aromatics may include benzene, toluene, pyridine, and pyrimidine. Examples of suitable alkyl halides may include ethyl fluoride, isopropyl bromide, and t-butyl chloride. Examples of suitable alkyl amines may include methylamine, dimethylamine, trimethylamine, and piperidine. Examples of suitable alkyl diamines may include ethylenediamine and 1,3-diaminopropane.

[0044] The term “chemical vapor deposition” (CVD) may generally represent a process in which a solid phase film is formed on a substrate by directing a continuous flow of one or more precursor vapors over the substrate surface under conditions configured to cause the chemical conversion of the precursor gases to the film. The term “plasma-enhanced chemical-vapor deposition” (PECVD) may generally represent a CVD process in which a plasma is used to facilitate the chemical conversion of one or more precursor gases to a solid phase film on a substrate. Thermal CVD (TCVD) processes utilize thermal energy to facilitate film formation.

[0045] The term “critical dimension” may generally represent a width of a feature of a substrate, such as a width of a gap formed in a substrate.Docket No. LRC24321PPCT

[0046] The term “feature” may generally represent substrate topology. For example, a feature can be a recess in a substrate. The term “gap” may generally represent a recessed feature in a substrate.

[0047] The term “field region” may generally represent surfaces of a substrate are oriented generally parallel to a plane of a substrate surface.

[0048] The term “flow control hardware” may generally represent 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.

[0049] The term “fluorine-containing inhibitor” may generally represent a compound that can be introduced into a processing chamber in a gas phase to deposit fluorine as an inhibitor on a substrate. Example fluorine-containing inhibitors can include fluorine (F2), nitrogen trifluoride (NF3), sulfur hexafluoride (SFe), hydrogen fluoride (HF), xenon difluoride (XeF?), various fluorocarbons (CxFy) such as tetrafluoromethane (CF4) or hexafluoroethane (C2F6), and various hydrofluorocarbons (CxHyFz).

[0050] The term “inhibition” and variants thereof generally represent a process by which a substance can disrupt one or more chemical processes for film growth on a substrate surface, thereby slowing growth of the film.

[0051] The term “inhibitor” may generally represent a substance 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. Example inhibitors include fluorine-containing inhibitors, nitrogen-containing inhibitors, and carbon- containing inhibitors.

[0052] The term “nitrogen-containing inhibitor” may generally represent any material that can be introduced into a processing chamber in a gas phase to deposit nitrogen as an inhibitor on a substrate. Example nitrogen-containing inhibitors can include nitrogen (N2), ammonia (NH3), hydrazine (N2H2), amines, diamines, and aminoalcohols.

[0053] The term “plasma” may generally represent a gas comprising cations and free electrons.Docket No. LRC24321PPCT

[0054] The term “precursor” may generally represent a substance that can be reacted to form a film on a substrate.

[0055] The term “process cycle” may generally represent a multi-step process that is repeated. As an example, a process cycle for an inhibited deposition process can comprise one or more deposition steps and one or more inhibition steps.

[0056] The term “processing chamber” may generally represent an enclosure in which chemical and / or physical processes are performed on substrates.

[0057] The term “processing tool” may generally represent a machine including a processing chamber and other hardware configured to enable substrate processing to be carried out in the processing chamber.

[0058] The term “showerhead” may generally represent a processing chemical outlet comprising a plurality of holes distributed across an area.

[0059] The term “substrate” may generally represent 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.

[0060] The term “substrate support” may generally represent any structure for supporting a substrate in a processing chamber.

[0061] 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) processes. ALD generally deposits films 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. ALD can be used to form highly conformal films on complex substrate topologies. ALD can be used to fill a recessed feature, or gap, on a substrate with a material. Such a process can be referred to as “gapfill”. One example of a material that can be used to fill a gap on a substrate is aluminum oxide. Aluminum oxide can be deposited by thermal ALD. In thermal ALD, the conversion of an aluminum-containing precursor to aluminum oxide on a substrate is accomplished by thermal energy, without plasma enhancement.

[0062] However, aluminum oxide ALD gapfill processes can pose various challenges. For example, high aspect ratio (HAR) gaps, such as gaps with aspect ratios equal to or greater than 1 :3 (width: depth), can be challenging to evenly fill with aluminum oxide using ALD. One difficulty encountered is seam formation. As layers of aluminum oxide film are progressively deposited within the gap, a seam can formDocket No. LRC24321PPCT where film growth fronts meet within the gap. This can arise at least partially due to the use of thermal ALD to deposit aluminum oxide, as the seam region is not densified by a plasma during the conversion of the aluminum-containing precursor to aluminum oxide. Such seams can be less dense than surrounding film regions. In a subsequent etching process, the etch chemistries can penetrate the seams and create spaces within the seam region. In a subsequent metal fill process, metal can intrude into the spaces, resulting in undesired metal fill.

[0063] As another challenge, a void may form in a gap during ALD aluminum oxide gapfill when the gap comprises a reentrancy. A reentrancy is a location in a gap at which a width is narrower than the width at a location deeper within the gap. As film layers grow on the reentrancy, growth fronts of the film can meet and pinch off at the reentrancy before deeper regions of the gap are fully filled, forming voids. Voids can cause similar downstream problems as seams.

[0064] FIGS. 1A-4C illustrate examples of such problems. First, FIGS. 1A-1C illustrate seam formation in an example aluminum oxide gapfill process used to fill gaps in the form of horizontal trenches in pillars. Such horizontal trenches can be formed in a gate-all-around field effect transistor (GAAFET) fabrication process.

[0065] FIG. 1A shows an example substrate 100. Substrate 100 comprises vertical trenches 102 that define pillars 104. Substrate 100 also comprises horizontal trenches 106 formed in the pillars 104 at different heights along each pillar 104. Trenches 106 can be filled with aluminum oxide in a gapfill process as part of a device fabrication process.

[0066] As shown in a magnified view 108 of pillar 104, each trench 106 comprises a sidewall 110 and a bottom 112. Next, FIG. IB shows substate 100 after partially completing the gapfill process. Here, an aluminum oxide film 114 is partially deposited conformally within trenches 106. Continuing, FIG. 1C shows substrate 100 after completing the gapfill of the horizontal trenches. As shown, seams, such as seam 116, have formed within the aluminum oxide film 114 where the growth fronts of the aluminum oxide film met during the ALD process. Seam 116 can have a lower density than surrounding regions of the aluminum oxide film, and can pose problems in downstream processing steps.

[0067] ALD gapfill also can lead to void formation, such as where a gap comprises a reentrancy. FIGS. 2A-2B illustrate void formation in a horizontal trench 202 in an example aluminum oxide gapfill process. The trench 202 comprises aDocket No. LRC24321PPCT reentrancy 204 at which a width 206 closer to an opening of the trench is narrower than a width 208 deeper within the trench. Referring next to FIG. 2B, which depicts the structure of FIG 2A after an aluminum oxide gapfill process, the growth fronts of aluminum oxide film 210 meet at the reentrancy 204 before meeting deeper within the gap due to the conformal nature of ALD. As such, a void 212 is formed. As mentioned above, this void can pose problems in downstream processing steps.

[0068] Similar issues can arise when filling vertical trenches. FIGS. 3A-3C illustrate seam formation in an example aluminum oxide gapfill process to fill a vertical trench. First, FIG. 3 A schematically shows a substrate 300 comprising a gap in the form of a vertical trench 302. Vertical trench 302 comprises a sidewall 304 and a bottom 306. FIG. 3B and FIG. 3C schematically show substrate 300 during and after completion of an aluminum oxide gapfill process performed using ALD. First referring to FIG. 3B, an aluminum oxide film 308 is partially deposited conformally within trench 302. Referring next to FIG. 3C, a seam 310 has formed within the aluminum oxide film where the growth fronts of aluminum oxide film 308 met.

[0069] FIGS. 4A-4C illustrate void formation in a substrate 400 comprising a vertical trench 402. Trench 402 comprises reentrancy 404, sidewall 406, and a bottom 408. FIG. 4B and FIG. 4C schematically show substrate 400 at different points during an aluminum oxide gapfill process. In FIG. 4B, an aluminum oxide film 410 has been partially deposited conformally within trench 402. Referring next to FIG. 4C, when the growth fronts of aluminum oxide film 410 meet along reentrancy 404, a void 414 can form within trench 402.

[0070] Accordingly, examples are disclosed that relate to performing void-free and seamless aluminum oxide gapfill by ALD. The term “seamless” indicates that a gapfill film lacks an interface where ALD growth fronts meet within the gap. The formation of a seamless and void-free gapfill film helps to ensure that the gapfill film has a similar etching rate throughout its bulk, thereby avoiding problems caused by a seam region with a faster etching rate than other film regions.

[0071] Briefly, the disclosed examples utilize the deposition of an inhibitor on a substrate under conditions such that a first concentration of the inhibitor deposited at a first depth within the gap is greater than a second concentration of the inhibitor deposited at a second, deeper depth within the gap. An inhibitor is a substance that can be applied to a substrate to affect one or more chemical and / or physical processes that occur during film deposition, to thereby reduce a rate of film growth. For example, anDocket No. LRC24321PPCT inhibitor can inhibit film precursor adsorption, inhibit film nucleation, and / or preferentially react with a reactant used to convert adsorbed precursor to a desired film material. After the deposition of the inhibitor, a plurality of ALD deposition cycles are performed. Each deposition cycle comprises exposing the substrate to an aluminum- containing precursor, and then reacting the adsorbed aluminum-containing precursor with an oxygen-containing reactant to form a layer of the aluminum oxide film. In this manner, aluminum oxide film growth can be more inhibited on the sidewalls of the gap at locations closer to an opening of the gap, and less inhibited or uninhibited deeper within the gap. This allows bottom-up, nonconformal film growth to occur, thereby helping to avoid seam and / or void formation. In some examples, inhibitor can be redeposited one or more times during the plurality of ALD deposition cycles. Further, in some examples, the reaction is driven thermally (using thermal ALD), rather than by plasma enhancement. The use of thermal ALD may allow for slower consumption of the inhibitor compared to PEALD. This can allow for less frequent inhibitor deposition, as well as more effective inhibition.

[0072] An aluminum oxide gapfill process according to the disclosed examples can utilize an aluminum-containing precursor with relatively lower reactivity compared to other aluminum-containing precursors. Examples of aluminum-containing precursors with relatively lower reactivity include aluminum-containing precursors with aluminum-oxygen bonds, and / or aluminum-containing precursors with vapor pressures within a range of 1 to 12 torr at 25 degrees Celsius. Such an aluminum- containing precursors may be less reactive with the adsorbed inhibitor compared to aluminum-containing precursors that lack aluminum-oxygen bonds and / or aluminum- containing precursors with vapor pressures above 12 torr at 25 degrees Celsius, and thereby remove less of the adsorbed inhibitor during a deposition cycle compared to the use of a relatively more reactive aluminum-containing precursor (e.g. one with a relatively higher vapor pressure and / or lacking aluminum-oxygen bonds). This can allow the inhibitor to more effectively inhibit aluminum oxide deposition than the use of a more reactive aluminum-containing precursor, encouraging bottom-up gapfill film growth. This also has the potential benefit of allowing fewer cycles of reapplication of inhibitor during the ALD deposition process than where a more reactive precursor that consumes inhibitor more quickly is used. However, in other examples, aluminum- containing precursors with vapor pressures above 12 torr at 25 degrees Celsius can be used. All ranges stated herein are inclusive of the endpoint values.Docket No. LRC24321PPCT

[0073] Process parameters used in aluminum oxide ALD can be controlled to tune various characteristics of the aluminum oxide film, such as density. An aluminum oxide film with a relatively higher density is etched more slowly than an aluminum oxide film with a relatively lower density. Thus, by controlling density of an aluminum oxide gapfill film, the etch rate of the aluminum oxide gapfill film can be controlled.

[0074] Various parameters can be controlled to control a density of an aluminum oxide film. One example parameter is temperature. Relatively higher substrate heater temperatures can lead to relatively denser aluminum oxide films, while relatively lower substrate heater temperatures can lead to relatively lower density aluminum oxide films.

[0075] Another example ALD process parameter that can be controlled to control aluminum oxide film density is precursor exposure time, which is an amount of time that a substrate is exposed to an aluminum-containing precursor in an aluminum oxide ALD cycle. Relatively shorter precursor exposure times can lead to relatively less dense aluminum oxide films. Likewise, relatively longer precursor exposure times can lead to relatively more dense aluminum oxide films.

[0076] Yet another example ALD process parameter that can be controlled to control aluminum oxide film density is reactant exposure time, which is an amount of time in an ALD cycle that a substrate is exposed to a reactant to convert adsorbed aluminum-containing precursor on the substrate to an aluminum oxide film layer. Relatively shorter reactant exposure times can lead to relatively less dense aluminum oxide films. Likewise, relatively longer reactant exposure times can lead to relatively more dense aluminum oxide films. Thus, one or more of substrate temperature, precursor exposure time, and / or reactant exposure time can be controlled to deposit an aluminum oxide film with an etch rate within a targeted range.

[0077] An inhibitor can be deposited using plasma-enhanced CVD (PECVD) in some examples. In a PECVD inhibitor deposition process, diffusion of reactive inhibitor species generated in a plasma can be controlled (e.g. by a time duration for exposure of the substrate to the reactive inhibitor species) such that relatively higher concentrations of inhibitor are deposited on substrate surfaces within the gap that are relatively closer to the gap opening, and relatively lower concentrations of inhibitor are deposited on surfaces relatively deeper within the gap. Relatively shorter exposure times to the inhibitor and / or relatively lesser concentrations of inhibitor in a gas flow mixture can be used to deposit the inhibitor relatively less deeply within a gap.Docket No. LRC24321PPCTSimilarly, relatively longer exposure times to the inhibitor and / or relatively higher concentrations of inhibitor in a gas flow mixture can be used to deposit the inhibitor relatively more deeply within a gap.

[0078] FIG. 5 shows an example plot of mean thicknesses of aluminum oxide films as a function of inhibitor exposure times at a substrate heater temperature of 360°C. The aluminum oxide films formed in this experiment were deposited as blanket films on unfeatured substrates using a dimethyl aluminum alkoxide precursor and a nitrogen-containing inhibitor according to the methods disclosed herein. The thickness data of FIG. 5 represents the effects of inhibitor exposure time on ALD processes using aluminum-containing precursor dose (exposure) times of 0.2 second and 0.4 second per ALD cycle. The illustrated exposure times are example times, and other exposure times, including shorter exposure times, also can be used. A same number of ALD cycles was used for each thickness measurement. As shown in FIG. 5, film thickness decreased as a function of increased inhibitor exposure time for both precursor dose times. Also, at 20 seconds inhibitor exposure time, less film thickness resulted for the 0.2 second aluminum-containing precursor dose time than for the 0.4 second aluminum-containing precursor dose time. Thus, FIG. 5 illustrates that ALD aluminum oxide film growth can effectively be inhibited, and that the growth rate is a function of both inhibitor exposure time and aluminum-containing precursor dose time. This indicates that inhibitor concentration on a substrate surface can be used to control film growth rate, such that forming a concentration gradient of inhibitor on the substrate can lead to different film growth rates based upon the different concentrations. As such, depositing a higher concentration of inhibitor on a substrate surface within a gap closer to an opening of a gap and a lower concentration of inhibitor on a substrate deeper within the gap can lead to a higher film growth rate deeper within the gap than closer to the opening of the gap. This can lead to bottom-up seam-free gapfill.

[0079] Other process parameters that can be controlled to control a depth within a gap to which an inhibitor is applied include plasma power, chamber pressure, and / or substrate bias. Relatively higher plasma powers can be used to activate relatively greater fractions of reactive inhibitor species within the plasma than relatively lower plasma powers. However, relatively higher plasma powers also can cause more ion bombardment of the substrate than relatively lower plasma powers. Ion bombardment can dislodge adsorbed inhibitor from the substrate surface. As such, plasma power can be controlled to achieve a suitable balance of these factors.Docket No. LRC24321PPCT

[0080] In some examples, a processing tool can allow a substrate bias voltage to be controlled. A higher bias voltage can drive more ions toward the substrate than a lower bias voltage. Thus, a relatively higher bias can be used to drive inhibitor ions from the plasma relatively deeper within the gap, while a relatively lower bias (or no bias) can be used to drive inhibitor ions relatively less deep within the gap. In processing tools having capacitively coupled plasma sources, bias can be controlled by using a multi -frequency plasma. In some such examples, a relatively higher frequency radiofrequency (HF RF) energy component can be used to excite the plasma, and a relatively lower frequency RF (LF RF) energy component can be used to control ion bombardment of the substrate. The term HF RF energy component may generally represent an RF energy component with a frequency of higher than 1 MHz. The term LF RF energy component may generally represent an RF energy component with a frequency of 1 MHz or lower. The amplitudes of both the HF RF and LF RF energy components can be controlled to achieve a desired inhibitor deposition. Further, in some examples, one or more of the HF RF energy component or the LF RF energy component can be pulsed in some examples. In yet further examples, a single frequency RF capacitively coupled plasma can be used.

[0081] Bias also can be controlled in processing tools that comprise inductively coupled plasmas. In such processing tools, plasma generation is achieved using an inductive coil. Then, a separate biasing electrode can be controlled to control bombardment of the substrate by reactive inhibitor ions generated in the inductively coupled plasma. Again, higher biases can be used to drive the reactive inhibitor ions from the plasma relatively more deeply within a gap.

[0082] Processing chamber pressure also can be controlled to help control inhibitor deposition. For example, relatively higher pressures can decrease the mean free path of the reactive inhibitor species. Collisions between reactive inhibitor species at such pressures can help prevent the high-energy ion bombardment from removing a portion or all of the inhibitor layer. Therefore, increasing the pressure inside the plasma deposition chamber can allow for a relatively higher plasma power to be used. An increase in chamber pressure can also reduce the directionality of the inhibitor deposition. This can help the reactive inhibitor species to deposit more uniformly on surfaces of different orientations than a more directional plasma.

[0083] In some gapfill film deposition processes, inhibitor can be consumed by the deposition process. Thus, as mentioned above, the inhibitor can be reapplied duringDocket No. LRC24321PPCT a deposition process, between at least two deposition cycles of the plurality of deposition cycles. In such examples, inhibitor deposition conditions can be changed to deposit inhibitor more deeply within a gap at an earlier time in the gapfill film deposition process, and to deposit inhibitor less deeply within the gap at one or more later times when the inhibitor is reapplied. In this manner, aluminum oxide deposition will be inhibited relatively deeper within the gap earlier in the gapfill film deposition process. The aluminum oxide thus will form a relatively thicker film at the bottom of the gap and a relatively thinner film at locations less deep within the gap. This helps to enable bottom-up seam-free gapfill. As the aluminum oxide film fills the gap from the bottom up, the later inhibitor reapplications that deposit inhibitor less deeply within the gap can be configured not to inhibit aluminum oxide deposition at the growth front within the gap.

[0084] FIG. 6 shows a flow diagram illustrating an example method 600 of performing aluminum oxide gapfill using inhibited ALD. The method 600 is performed in a processing chamber of a processing tool. An example processing tool is described below with regard to FIG. 9. FIG. 6 is described with reference to FIGS. 7A-7F and FIGS. 8A-8F. FIGS. 7A-7F illustrate an example implementation of method 600 to perform gapfill in horizontal trenches 702 in a substrate 700. FIGS. 8A-8F illustrate an example implementation of method 600 to perform gapfill in a vertical trench 802 in a substrate 800.

[0085] Method 600 comprises, at 602, depositing an inhibitor on a substrate under conditions such that a first concentration of the inhibitor deposited at a first depth within a gap on the substrate is greater than a second concentration of the inhibitor deposited at a second depth within the gap. The second depth is deeper within the gap than the first depth. In some examples, the inhibitor is deposited using a plasma 604, such as by plasma enhanced chemical vapor deposition (PECVD).

[0086] The inhibitor can comprise any suitable substance that can be adsorbed to a substrate surface to inhibit aluminum oxide film deposition by ALD. Example inhibitors include hydrogen (EE), nitrogen-containing inhibitors, fluorine-containing inhibitors, and carbon-containing inhibitors. Example nitrogen-containing inhibitors can include nitrogen (N2), ammonia (NH3), hydrazine (N2H2), amines, diamines, and aminoalcohols. Examples of fluorine-containing inhibitors can include fluorine (F2), nitrogen trifluoride (NF3), sulfur hexafluoride (SFe), hydrogen fluoride (HF), xenon difluoride (XeF2), fluorocarbons (CxFy) such as tetrafluoromethane (CF4) orDocket No. LRC24321PPCT hexafluoroethane (C2F6), and hydrofluorocarbons (CxHyFz). Examples of carbon- containing inhibitors can include alkanes, alkenes, alkynes, cyclic hydrocarbons, aromatics, alcohols, aldehydes, esters, ethers, ketones, aldehydes, alkyl halides, alkyl amines, and alkyl diamines.

[0087] The depth to which inhibitor is deposited within a gap can be controlled by such parameters as inhibitor exposure time, plasma conditions used to deposit the inhibitor (e.g. a power level for each of one or more frequencies of the plasma), processing chamber pressure, and / or substate temperature. For example, the use of a relatively shorter inhibitor exposure time can result in the deposition of inhibitor relatively less deep within a gap, compared to the use of a relatively longer inhibitor exposure time. Further, the use of a multi -frequency component with an LF RF power component and an HF RF power component can result in the deposition of inhibitor relatively deeper within a gap, compared to the use of a single frequency plasma with only an HF RF power component. Also, the use of relatively lower processing chamber pressures can result in more directional inhibitor deposition than the use of relatively higher processing chamber pressures.

[0088] In some examples, a single frequency capacitively coupled plasma is used to deposit the inhibitor. In such examples, the plasma can have a power within a range of 0 to 1500 W per processing station. In other examples, a multi -frequency plasma can be used, wherein a HF RF power component of the multi-frequency plasma is used for plasma excitation, and a LF RF power component of the multi -frequency plasma controls a bias used to accelerate ions formed in the plasma toward the substrate. As described above, the HF RF energy component may generally represent an RF energy component with a frequency of higher than 1 MHz, and the LF RF energy component may generally represent an RF energy component with a frequency of 1 MHz or lower. In such examples, the HF RF power component can have a power within a range of 25 to 1500 W per processing station, and the LF power component can have a power within a range of 0 to 1250W per processing station. Example processing chamber pressures for the deposition of the inhibitor include processing chamber pressures within a range of 1 to 30 torr. Example temperatures include substrate heater (pedestal) temperatures of 250 - 650 degrees Celsius.

[0089] FIGS. 7A-7B illustrate substrate 700 comprising horizontal trenches 702 before and after inhibitor deposition, such as the inhibitor deposition step 602 of method 600. As shown in FIG. 7B schematically by a thickness of a layer of theDocket No. LRC24321PPCT inhibitor 704, a greater concentration of inhibitor deposits on the outer portions of substrate 700 and at a first depth 701 (as shown by dashed line) within trenches 702 in substrate 700, and a lesser concentration of inhibitor deposits at a second depth (as shown by dashed line 703) deeper within the trenches 702 in substrate 700. The thickness of inhibitor 704 in FIG. 7B is not intended to represent an actual inhibitor layer thickness, but again is a schematic representation of a concentration of the inhibitor on the surface of the substrate.

[0090] Similarly, FIGS. 8A-8B illustrate substrate 800 before and after inhibitor deposition, such as the inhibitor deposition step 602 of method 600. As shown in FIG. 8B schematically by a thickness of a layer of the inhibitor 804, a greater concentration of inhibitor deposits on the outer portions of substrate 800 and at a first depth (shown by dashed line 801) within vertical trench 802 in substrate 800, and a second, lesser concentration of inhibitor deposits at a second depth (shown by dashed line 803) deeper within trench 802 in substrate 800.

[0091] Returning to FIG. 6, method 600 comprises purging the processing chamber at 608. Purging the processing chamber at 608 removes excess inhibitor from the processing chamber. Method 600 further comprises, at 610, performing an ALD cycle.

[0092] Performing the ALD cycle at 610 comprises, at 612, exposing the substrate to an aluminum-containing precursor. In some examples, as indicated at 614, the aluminum-containing precursor comprises an organoaluminum compound with a vapor pressure within a range of 1 to 12 torr at 25 degrees Celsius. Alternatively or additionally, the aluminum-containing precursor comprises aluminum-oxygen bonds. As mentioned above, such aluminum-containing precursors can be less reactive toward the inhibitor than aluminum-containing precursors without aluminum-oxygen bonds and / or aluminum containing precursors with a vapor pressure of higher than 12 torr at 25 degrees Celsius. In some such examples, the aluminum-containing precursor comprises one or more of dimethyl aluminum isopropoxide, dimethyl aluminum ethoxide, or dimethyl aluminum methoxide. In other examples, an aluminum- containing precursor with a vapor pressure higher than 12 torr at 25 degrees Celsius, and / or lacking aluminum-oxygen bonds, can be used. In some examples, at 628, exposing the substrate to the aluminum-containing precursor comprises varying the precursor exposure time. As mentioned above, varying the precursor exposure timeDocket No. LRC24321PPCT between different aluminum oxide deposition cycles can vary the density of the resulting aluminum oxide gapfill film.

[0093] Continuing, performing the ALD cycle 610 further comprises purging the processing chamber at 616. Purging the processing chamber at 616 removes excess aluminum-containing precursor from the processing chamber. ALD cycle 610 further comprises, at 618, reacting the adsorbed aluminum-containing precursor with an oxygen-containing reactant to convert the aluminum-containing precursor to a layer of aluminum oxide film. In step 618, an oxygen-containing reactant is flowed into the processing chamber under processing conditions configured to cause a reaction between the oxygen-containing reactant and the adsorbed aluminum-containing precursor to form a layer of aluminum oxide film. Regions of the substrate with a higher concentration of inhibitor experience a greater degree of inhibition of the formation of the aluminum oxide film. The inhibition can be due to the inhibitor impeding precursor adsorption, impeding film nucleation, reacting preferentially with the oxygencontaining reactant, and / or another suitable mechanism. As such, as more ALD cycles are performed, regions of the substrate with higher concentrations of inhibitor (e.g. relatively less deep within the gap) will experience a lower aluminum oxide film growth rate than regions of the substate with lower concentrations of inhibitor (e.g. relatively deeper within the gap). Any suitable oxygen-containing reactant can be used. Some oxygen-containing reactants can react without plasma excitation in a thermal ALD process. Such oxygen-containing reactants include water vapor and ozone. In such examples, the substrate can be heated to any suitable temperature to help cause the reaction of the oxygen-containing reactant and adsorbed aluminum-containing precursor. Examples include substrate heater (pedestal) temperatures of 250 - 650 degrees Celsius. Other oxygen-containing reactants can utilize plasma activation in a plasma enhanced ALD (PEALD process). Such oxygen-containing reactants include molecular oxygen, nitrogen oxides, alcohols, carbon oxides (e.g. carbon monoxide or carbon dioxide), or sulfur oxides. In more specific examples, the oxygen-containing reactant comprises one or more of water, ozone, tert-butyl alcohol, or nitrous oxide. In some examples, at 620, reacting the adsorbed aluminum-containing precursor with the oxygen-containing reactant comprises varying the reactant exposure time between different aluminum oxide deposition cycles to vary the density of the resulting aluminum oxide gapfill film.Docket No. LRC24321PPCT

[0094] Continuing with FIG. 6, ALD cycle 610 further comprises purging the processing chamber at 622. Purging the processing chamber removes excess reactant from the processing chamber.

[0095] FIG. 7C schematically illustrates an example of an aluminum oxide film 705 partially deposited within trenches 702 after performing one or more ALD cycles 610 of method 600. As shown, the aluminum oxide film is thicker at deeper portions of trenches 702, such as in region 706. Likewise, aluminum oxide film growth is inhibited on portions of substrate 700 on which the layer of inhibitor 704 is deposited. Some deposited inhibitor can be consumed during the deposition process, as shown by the thinning of the layer of inhibitor 704 (again, which indicates inhibitor concentration on the substrate 700 at various locations rather than inhibitor layer thickness).

[0096] Similarly, FIG. 8C schematically illustrates an example of an aluminum oxide film 805 partially deposited within trench 802 within substrate 800 after performing one or more ALD cycles 610 of method 600. As shown, the aluminum oxide film is thicker at a deeper portion of trench 802, such as in region 806. Likewise, aluminum oxide film growth is inhibited on portions of substrate 800 on which the layer of inhibitor 804 is deposited. As mentioned above, the deposited inhibitor can be consumed during the deposition process, as illustrated by the thinning of the layer of inhibitor 804.

[0097] Continuing with FIG. 6, method 600 further comprises, at 624, determining whether to repeat ALD cycle 610. If it is determined at 624 to repeat the ALD cycle 610, then method 600 returns to 612, where another exposure of the substrate to the aluminum-containing precursor is performed. If the determination at 624 is to not repeat ALD cycle 610, then method 600 comprises, at 626, determining whether to repeat depositing the inhibitor on the substrate. If the determination at step 626 is to not repeat depositing the inhibitor on the substrate, then method 600 ends. On the other hand, if it is determined at 626 to redeposit the inhibitor, the method returns to 602 for the inhibitor redeposition, followed by an additional purge at 608 and one or more additional ALD cycles at 610. In this manner, a seam-free aluminum oxide gapfill film can be deposited by ALD. FIG. 7D schematically illustrates substrate 700 after depositing an additional layer of inhibitor 704. As mentioned above, in some examples, deposition parameters may be controlled such that the inhibitor deposits with a different concentration profile than in the previous deposition of inhibitor. For example, the inhibitor may be deposited less deeply within trench 702 than an initial deposition ofDocket No. LRC24321PPCT inhibitor. FIG. 7D shows substrate 700 after the inhibitor is redeposited at a shallower depth (as shown by dashed line 710) within trenches 702 than in the initial inhibitor deposition illustrated in FIG. 7B.

[0098] FIG. 7E illustrates substrate 700 after performing one or more additional ALD cycles. As shown by the thinning of the layer of inhibitor 704, some deposited inhibitor can be consumed during the deposition process. FIG. 7F illustrates substrate 700 after further performing an additional one or more ALD cycles 610 of method 600. As shown, trenches 702 are filled with the aluminum oxide film 705 without formation of voids or seams. In this example, the inhibitor is consumed during a deposition process. In other examples, the inhibitor can be removed in a separate step, which can be referred to as passivation. Passivation can utilize an oxidative or reducing plasma in various examples, depending upon the inhibitor that was used and the other substrate materials exposed to the plasma.

[0099] FIG. 8D schematically illustrates substrate 800 after depositing an additional layer of inhibitor 804. As mentioned above, in some examples, the inhibitor can be deposited less deeply within trench 802 than an initial deposition of inhibitor. In other examples, such as shown in FIG. 8D by dashed line 803, the additional layer of inhibitor 804 can be re-deposited to a same or similar depth within trench 802 as the initial deposition of layer of inhibitor 804 shown in in FIG 8B.

[0100] FIG. 8E illustrates substrate 800 after repeating one or more ALD cycles 610 of method 600. As shown by the thinning of the layer of inhibitor 804, some deposited inhibitor can be consumed during the deposition process. FIG. 8F illustrates trench 802 after performing further ALD. As shown, trench 802 is filled with the aluminum oxide film 805 without formation of voids or seams, and the inhibitor is consumed. Returning to FIG. 6, after complete seamless gapfill of trenches 802, method 600 ends.

[0101] As mentioned above, seams and voids can pose problems in downstream processing steps. FIGS. 9A-9C schematically show an example of aluminum oxide seam failure in a wet etch process. FIG. 9A shows a substrate 900 comprising stacked channel structures 902. Channel structures 902 can be channel structures formed in a gate-all-around field effect transistor (GAAFET) or complementary FET (CFET) fabrication process. Channel structures 902 define horizontal gaps 904 and a vertical trench 906. FIG. 9B shows substrate 900 after an aluminum oxide film gapfill process to deposit an aluminum oxide film 908 between channel structures 902. As shown,Docket No. LRC24321PPCT aluminum oxide film 908 is deposited in horizontal gaps 904 between channel structures 902 and on sidewalls of vertical trench 906. Growth fronts of the aluminum oxide film 908 meet during the gapfill process, forming lower-density seams 910 within horizontal gaps 904. In this example, a downstream processing step comprises etching the aluminum oxide film 908 from sidewalls of vertical trench 906 in a wet etch process while leaving aluminum oxide film 908 in horizontal gaps 904 between channel structures 902. FIG. 9C schematically shows substrate 900 after a wet etching process. As shown, lower-density seams 910 are etched more quickly than the surrounding aluminum oxide film 908, resulting in seam failure.

[0102] To address the problems described in FIGS. 9A-9C, ALD parameters can be controlled to deposit an aluminum oxide film comprising a varied density. A first portion of an aluminum oxide film having a first density can be deposited, and then a second portion of the aluminum oxide film having a second density that is different than the first density can be deposited. For example, the first portion of the aluminum oxide film can have a lower density, and the second portion of the aluminum oxide film can have a higher density. The resulting aluminum oxide film thus comprises lower- density portions exhibiting a higher etch rate, and higher-density portions exhibiting a lower etch rate.

[0103] For example, seam regions of a gapfill film can comprise a lower density and can fail during downstream etching processes. Thus, depositing a higher-density aluminum oxide film in the seam regions and a lower-density aluminum oxide film farther from the seam regions can help to mitigate this effect by reducing a difference in the etch rate between the seam regions and other regions. This can help to achieve a more consistent etch rate of the film. In some examples, the aluminum oxide film can be deposited using inhibited ALD in addition to controlling the ALD parameters to tune the density of the aluminum oxide film. This can be done to avoid seam formation.

[0104] FIGS. 10A-10D schematically show substrate structures formed in a substrate 1000 in an aluminum oxide gapfill process to deposit an aluminum oxide film comprising a varied density. FIG. 10A shows a substrate 1000 after performing a first set of one or more deposition cycles using a first set of deposition parameters to deposit a lower-density aluminum oxide film portion 1008 on the substrate. The first set of one or more deposition cycles comprises a first substrate temperature, a first aluminum- containing precursor exposure time, and a first reactant exposure time. Substrate 1000 comprises channel structures 1002, such as channel structures formed in a gate allDocket No. LRC24321PPCT around field effect transistor (GAAFET) or complementary FET (CFET) fabrication process. Channel structures 1002 define horizontal gaps 1004 and a vertical trench 1006. An enlarged view of a portion of substrate 1000 is also shown in FIG. 10A. As shown, a lower-density aluminum oxide film portion 1008 is deposited conformally on surfaces of channel structures 1002.

[0105] FIG. 10B schematically shows the enlarged view of the portion of substrate 1000 during deposition of a higher-density aluminum oxide film portion 1010 on channel structures 1002. A second set of one or more deposition cycles can be performed to deposit a higher-density aluminum oxide film portion 1010. The second set of one or more deposition cycles comprises one or more different deposition parameters than the first set of deposition parameters. For example, the second set of deposition parameters can comprise one or more of a second substrate temperature, a second aluminum-containing precursor exposure time, or a second reactant exposure time that is or are different from corresponding parameters of the first set of deposition parameters. As a more specific example, the second set of deposition parameters may have one or more of a higher substrate temperature, a longer aluminum-containing precursor exposure time, or a longer reactant exposure time than the first set of deposition parameters to form a higher-density second film portion and a lower-density first film portion. As higher-density aluminum oxide film portion 1010 is deposited, growth fronts of higher-density aluminum oxide film portion 1010 begin growing together within horizontal gap 1004.

[0106] Next, FIG. 10C schematically shows the enlarged view of the portion of substrate 1000 after performing the second set of one or deposition cycles using a second set of parameters to thereby deposit the higher-density aluminum oxide film portion 1010. As shown, higher-density aluminum oxide film portion 1010 completely fills horizontal gap 1004. Growth fronts of higher-density aluminum oxide film portion 1010 grow together to form a relatively lower-density seam 1012. However, due to the relatively higher density of higher-density aluminum oxide film 1010, the overall etch rate of the aluminum oxide film formed within horizontal gap 1004 is suitably consistent.

[0107] FIG. 10D schematically shows the enlarged view of the portion of substrate 1000 after performing a wet etching process to etch portions of higher-density aluminum oxide film portion 1010 from sidewalls of vertical trench 1006. As shown, due to the relatively higher-density of aluminum oxide film portion 1010, the etchingDocket No. LRC24321PPCT chemistry does not penetrate into horizontal gap 1004, thereby avoiding seam failure. In this manner, deposition parameters can be controlled to achieve desired densities and thereby achieve consistent recess etch rates of the aluminum oxide film within complex substrate topography. Further, as mentioned above, in some examples inhibited ALD according to method 600 can be performed in addition to variable deposition to achieve seam-free gapfill of a material with a varied density within gaps in a substrate.

[0108] FIG. 11 schematically shows an example processing tool that can be used to perform aluminum oxide gapfill, such as by method 700 of FIG. 7. Processing tool 1100 comprises a processing chamber 1102. A substrate support 1104 and a showerhead 1110 are disposed in the processing chamber 1102. A substrate 1106 can be positioned on substrate support 1104 during operation of the processing tool 1100. Substrate support 1104 comprises a substrate heater 1108 configured to supply thermal energy to substrate 1106. In other examples, the substrate heater may be omitted, or may be located elsewhere within processing chamber 1102. Processing chemicals can be introduced into processing chamber 1102 through a processing chemical outlet in the form of a showerhead 1110. Alternatively or additionally, in other examples, a processing chemical outlet other than a showerhead, such as one or more nozzles, can be used to introduce processing chemicals into processing chamber 1102.

[0109] Processing tool 1100 further comprises flow control hardware 1112. Flow control hardware 1112 connects processing chemical sources to processing chamber 1102. In the depicted example, flow control hardware 1112 connects an inhibitor source 1114, an aluminum-containing precursor source 1116, an oxygen- containing reactant source 1122, and an inert gas source 1124 to the processing chamber. The processing chemical sources may comprise processing chemicals in liquid, solid, or gas form. In some embodiments, flow control hardware 1112 can connect a passivator source to the chamber (not shown). The passivator source can contain a passivator used to remove inhibitor deposited on the substrate in such examples.

[0110] The inhibitor source 1114 can comprise any suitable inhibitor for inhibiting the adsorption of the aluminum-containing precursor. In some examples, the inhibitor comprises one or more of a nitrogen-containing, a carbon-containing, or a fluorine-containing inhibitor. Examples of such inhibitors include hydrogen (EE), nitrogen-containing inhibitors, fluorine-containing inhibitors, and carbon-containing inhibitors. Example nitrogen-containing inhibitors can include nitrogen (N2), ammoniaDocket No. LRC24321PPCT(NF ), hydrazine (N2H2), amines, diamines, and aminoalcohols. Examples of fluorine- containing inhibitors can include fluorine (F2), nitrogen trifluoride (NF3), sulfur hexafluoride (SFe), hydrogen fluoride (HF), xenon difluoride (XeF2), fluorocarbons (CxFy) such as tetrafluoromethane (CF4) or hexafluoroethane (C2F6), and hydrofluorocarbons (CxHyFz). Examples of carbon-containing inhibitors can include alkanes, alkenes, alkynes, cyclic hydrocarbons, aromatics, alcohols, aldehydes, esters, ethers, ketones, aldehydes, alkyl halides, alkyl amines, and alkyl diamines.

[0111] The aluminum-containing precursor source 1116 can comprise any suitable precursor for forming an aluminum oxide film. As mentioned above, it can be advantageous in some examples to use a relatively less reactive aluminum-containing precursor for seam-free aluminum oxide gapfill according to the disclosed examples. Thus, in some examples, the aluminum-containing precursor comprises an aluminum- containing precursor having one or more aluminum-oxygen bonds 918. Additionally or alternatively, at 920, the aluminum-containing precursor can comprise an aluminum- containing precursor with a vapor pressure within a range of 1 to 12 torr at 25 degrees Celsius. More specific examples of aluminum-containing precursors include dimethyl aluminum isopropoxide, dimethyl aluminum ethoxide, or dimethyl aluminum methoxide.

[0112] The oxygen-containing reactant source 1122 can comprise any suitable reactant that can react with the aluminum-containing precursor to form an aluminum oxide film. In some examples, the oxygen-containing reactant comprises one or more of water vapor, an alcohol, or ozone. Suitable alcohols can include methanol, ethanol, propanol, and tert-butyl alcohol. In other examples, oxygen-containing reactant can comprise molecular oxygen, nitrogen oxides, carbon oxides (e.g. carbon monoxide or carbon dioxide), or sulfur oxides.

[0113] The inert gas source 1124 can comprise any suitable inert gas. Examples include one or more of argon, helium, neon, krypton, and xenon, or nitrogen (in environments in which nitrogen does not become reactive, such as in thermal ALD environments). The inert gas source 1124 can provide an inert gas as a carrier gas for one or more of the inhibitor, aluminum-containing precursor, or oxygen-containing reactant. One or more inert gases also can be used for purging the processing chamber 1102.

[0114] Flow control hardware 1112 can comprise any suitable components. Examples include mass flow controllers, valves, and conduits. For example, flowDocket No. LRC24321PPCT control hardware 1112 can comprise one or more valves controllable to place a selected processing chemical source in fluid connection with showerhead 1110. Flow control hardware 1112 also can comprise one or more mass flow controllers or other controllers for controlling a mass flow rate of gas.

[0115] Processing tool 1100 further comprises a radiofrequency (RF) power source 1132 electrically connected to substrate support 1104. RF power source 1132 is configured to form a plasma within processing chamber 1102. Showerhead 1110 is configured as a grounded opposing electrode in this example. In other examples, RF power source 1132 can be configured to supply RF power to showerhead 1110 and substrate support 1104 can be grounded. In further examples, RF power source 1132 can be configured to supply RF power to another suitable electrode structure.

[0116] Processing tool 1100 further includes a matching network 1130 for impedance matching of the RF power source 1132. The RF power source 1132 can be configured to provide radiofrequency energy of any suitable frequency and power. Example frequencies include radiofrequencies of 300 MHz and below. More specific example frequencies include 13.56 MHz and 27 MHz. Example powers include powers within a range of 0 to 1500 W (per processing station). In some examples, RF power source 1132 can be configured to operate at a plurality of different frequencies and / or powers. For example, a plasma can comprise a LF RF component and a HF RF component. Examples of frequencies for the LF RF component can include frequencies of 1 MHz and below. The LF RF component can comprise a power per station of 0 to 1250 W, in some examples. Further, the HF radiofrequency energy component can comprise frequencies of 1 MHz to 300 MHz. The HF RF component can comprise a power of 25 to 1500 W, in some examples.

[0117] Exhaust system 1134 is configured to exhaust gases from processing chamber 1102. The exhaust system 1134 can comprise any suitable hardware, including one or more low vacuum pumps and one or more high vacuum pumps. Flow control hardware 1112 and exhaust system 1134 can be operated together to achieve a selected pressure in processing chamber 1102 during substrate processing. For example, in a purge processing step, flow control hardware 1112 can be operated to introduce an inert gas from inert gas source 1124, and exhaust system 1134 can be operated to exhaust processing chamber 1102.

[0118] Processing tool 1100 further comprises a controller 1128 configured to control operation of processing tool 1100. Controller 1128 is operatively coupled toDocket No. LRC24321PPCT other components of the processing tool 1100 to cause the processing tool 1100 to perform deposition of an inhibitor on a substrate under conditions such that a first concentration of the inhibitor deposited at a first depth within the gap is greater than a second concentration of the inhibitor deposited at a second depth within the gap, wherein the second depth is deeper within the gap than the first depth. Controller 1128 is further operatively coupled to control the processing tool to cause the processing tool to perform a plurality of deposition cycles, each deposition cycle comprising exposing the substrate to an aluminum-containing precursor, and reacting adsorbed aluminum- containing precursor with an oxygen-containing reactant to form a layer of an aluminum oxide film. Controller 1128 is further operatively coupled to optionally cause redeposition of the inhibitor between at least two deposition cycles of the plurality of deposition cycles.

[0119] Controller 1128 is operatively coupled to flow control hardware 1112, RF power source 1132, matching network 1130, and exhaust system 1134. Controller 1128 is operatively coupled to flow control hardware 1112 to deliver processing chemicals to the showerhead, as described above. Controller 1128 is further operatively coupled to RF power source 1132 and matching network 1130 to form a plasma, as described above. Controller 1128 is further operatively coupled to control exhaust system 1134 to remove gases from processing chamber 1102, as described above. Controller 1128 can comprise any suitable computing system. Example computing systems are described in further detail below with reference to FIG. 12.

[0120] FIG. 12 schematically shows a non-limiting example of a computing system 1200 that can enact one or more of the methods and processes described above. Computing system 1200 is shown in simplified form. Computing system 1200 may take the form of one or more personal computers, workstations, computers integrated with substrate processing tools, and / or network accessible server computers.

[0121] Computing system 1200 includes a logic machine 1202 and a storage machine 1204. Computing system 1200 may optionally include a display subsystem 1206, input subsystem 1208, communication subsystem 1210, and / or other components not shown in FIG. 12. Controller 1028 is an example of computing system 1200.

[0122] Logic machine 1202 includes one or more physical devices configured to execute instructions. For example, the logic machine may be configured to execute instructions that are part of one or more applications, services, programs, routines, libraries, objects, components, data structures, or other logical constructs. SuchDocket No. LRC24321PPCT 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.

[0123] The logic machine 1202 may include one or more processors configured to execute software instructions. Additionally or alternatively, the logic machine 1202 may include one or more hardware or firmware logic machines configured to execute hardware or firmware instructions. Processors of the logic machine 1202 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 machine 1202 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 machine 1202 may be virtualized and executed by remotely accessible, networked computing devices configured in a cloud-computing configuration.

[0124] Storage machine 1204 includes one or more physical devices configured to hold instructions 1212 executable by the logic machine to implement the methods and processes described herein. When such methods and processes are implemented, the state of storage machine 1204 may be transformed — e.g., to hold different data.

[0125] Storage machine 1204 may include removable and / or built-in devices. Storage machine 1204 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 machine 1004 may include volatile, nonvolatile, dynamic, static, read / write, read-only, random-access, sequential-access, location-addressable, file- addressable, and / or content-addressable devices.

[0126] It will be appreciated that storage machine 1204 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.

[0127] Aspects of logic machine 1202 and storage machine 1204 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.Docket No. LRC24321PPCT

[0128] When included, display subsystem 1206 may be used to present a visual representation of data held by storage machine 1204. 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 machine, and thus transform the state of the storage machine, the state of display subsystem 1206 may likewise be transformed to visually represent changes in the underlying data. Display subsystem 1206 may include one or more display devices utilizing virtually any type of technology. Such display devices may be combined with logic machine 1202 and / or storage machine 1204 in a shared enclosure, or such display devices may be peripheral display devices.

[0129] When included, input subsystem 1208 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 voice recognition, and an infrared, color, stereoscopic, and / or depth camera for machine vision and / or gesture recognition.

[0130] When included, communication subsystem 1210 may be configured to communicatively couple computing system 1200 with one or more other computing devices. Communication subsystem 1210 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 1200 to send and / or receive messages to and / or from other devices via a network such as the Internet.

[0131] 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.Docket No. LRC24321PPCT

[0132] 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. LRC24321PPCTCLAIMS:

1. A method of filling a gap on a substrate, the method comprising; depositing an inhibitor on the substrate under conditions such that a first concentration of the inhibitor deposited at a first depth within the gap is greater than a second concentration of the inhibitor deposited at a second depth within the gap, wherein the second depth is deeper within the gap than the first depth; and performing a plurality of deposition cycles, each deposition cycle comprising exposing the substrate to an aluminum-containing precursor, and reacting adsorbed aluminum-containing precursor with an oxygencontaining reactant to form a layer of the aluminum oxide film.

2. The method of claim 1, further comprising redepositing the inhibitor between at least two deposition cycles while performing the plurality of deposition cycles.

3. The method of claim 1, wherein a plasma is used to deposit the inhibitor.

4. The method of claim 3, wherein the inhibitor comprises one or more of a nitrogen-containing compound, a halogen-containing compound, or a carbon- containing compound.

5. The method of claim 3, wherein the inhibitor comprises one or more of nitrogen (N2), ammonia (NH3), an amine, a diamine, or an aminoalcohol.

6. The method of claim 1, wherein reacting the adsorbed aluminum-containing precursor with the oxygen-containing reactant comprises using thermal energy in the absence of a plasma to react the adsorbed aluminum-containing precursor with the oxygen-containing precursor.

7. The method of claim 1, wherein the oxygen-containing reactant comprises one or more of molecular oxygen, a nitrogen oxide, a carbon oxide, ozone, water vapor, or an alcohol.

8. The method of claim 1, wherein the plurality of deposition cycles are performed at a substrate holder temperature within a range of 250 and 650 degrees Celsius.Docket No. LRC24321PPCT9. The method of claim 1, wherein the aluminum-containing precursor comprises an organoaluminum compound with a vapor pressure within a range of 1 to 12 torr at 25 degrees Celsius.

10. The method of claim 9, wherein the aluminum-containing precursor comprises one or more of dimethyl aluminum isopropoxide, dimethyl aluminum ethoxide, or dimethyl aluminum methoxide.

11. The method of claim 1, wherein the gap is a horizontal trench in a gate-all- around field effect transistor (GAAFET) device.

12. A method of filling a gap on a substrate, the method comprising; depositing an inhibitor on the substrate under conditions such that a first concentration of the inhibitor deposited at a first depth within the gap is greater than a second concentration of the inhibitor deposited at a second depth, wherein the second depth is deeper depth within the gap than the first depth; and performing a plurality of thermal chemical vapor deposition (CVD) process deposition cycles, each deposition cycle comprising exposing the substrate to an aluminum-containing precursor, the aluminum-containing precursor comprising an organoaluminum compound, and thermally reacting adsorbed aluminum-containing precursor with an oxygen-containing reactant to form a layer of the aluminum oxide film.

13. The method of claim 12, wherein the inhibitor comprises one or more of nitrogen (N2), ammonia (NH3), an amine, a diamine, or an aminoalcohol.

14. The method of claim 12, wherein depositing the inhibitor on the substrate under conditions 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, deeper depth within the gap comprises using a plasma to deposit the inhibitor.Docket No. LRC24321PPCT15. The method of claim 12, wherein the organoaluminum compound comprises one or more of dimethyl aluminum isopropoxide, dimethyl aluminum ethoxide, or dimethyl aluminum methoxide.

16. A processing tool, comprising a processing chamber; a substrate holder in the processing chamber; a sub state heater; a showerhead; flow control hardware configured to deliver processing chemicals to the showerhead; and a power source configured to form a plasma for processing substrates; wherein the processing tool is configured to deposit an inhibitor on a substrate under conditions such that a first concentration of the inhibitor deposited at a first depth within a gap is greater than a second concentration of the inhibitor deposited at a second depth within the gap, wherein the second depth is deeper within the gap than the first depth; and perform a plurality of deposition cycles, each deposition cycle comprising exposing the substrate to an aluminum-containing precursor, and reacting adsorbed aluminum-containing precursor with an oxygen-containing reactant to form a layer of an aluminum oxide film.

17. The processing tool of claim 16, wherein the processing tool is further configured to cause redeposition of the inhibitor between at least two deposition cycles, while performing the plurality of deposition cycles.

18. The processing tool of claim 16, wherein the inhibitor comprises one or more of nitrogen (N2), ammonia (NH3), an amine, a diamine, or an aminoalcohol.

19. The processing tool of claim 16, wherein the aluminum-containing precursor comprises one or more of dimethyl aluminum isopropoxide, dimethyl aluminum ethoxide, or dimethyl aluminum methoxide.Docket No. LRC24321PPCT20. The processing tool of claim 16, wherein the oxygen-containing reactant comprises one or more of molecular oxygen, a nitrogen oxide, a carbon oxide, ozone, water vapor, or an alcohol.

21. A method of depositing an aluminum oxide gapfill film comprising a varied density within a gap on a substrate, the method comprising; performing a first set of one or more deposition cycles with a first set of deposition parameters to form a first portion of the aluminum oxide film with a first density; and performing a second set of one or more deposition cycles with a second set of deposition parameters to form a second portion of the aluminum oxide film with a second density.

22. The method of claim 21, wherein the first set of deposition parameters comprises a first temperature and the second set of deposition parameters comprises a second temperature.

23. The method of claim 21, wherein the first set of deposition parameters comprises a first aluminum-containing precursor exposure time, and wherein the second set of deposition parameters comprises a second aluminum-containing precursor exposure time.

24. The method of claim 21, wherein the first set of deposition parameters comprises a first reactant exposure time, and wherein the second set of deposition parameters comprises a second reactant exposure time.

25. The method of claim 21 , wherein the second portion of the aluminum oxide film is a seam portion of the aluminum oxide gapfill film, and wherein the second density is higher than the first density.

26. The method of claim 21, wherein the method further comprises depositing an inhibitor on the substrate under conditions such that a first concentration of the inhibitor deposited at a first depth within the gap is greater than aDocket No. LRC24321PPCT second concentration of the inhibitor deposited at a second depth within the gap, wherein the second depth is deeper within the gap than the first depth.

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