Circulating etch and deposition for controlling film profiles

Abstract

Examples disclosed relate to controlling the growth profile of a silicon-containing film deposited on features of a substrate. One example provides a method of performing a cyclic chemical vapor deposition (CVD) / etch process to control the profile of a silicon-containing film deposited on a substrate including a spacer structure. Each spacer structure includes a top field region (top field) and one or more sidewalls. The method includes performing a plurality of alternating CVD and etch steps. Each CVD step includes depositing portions of the silicon-containing film on the spacer structures of the substrate. Each etching step includes forming a plasma using a gas mixture including a halogen-containing etchant to adjust the profile of the silicon-containing film.

Description

BACKGROUND

[0001] Electronic device manufacturing processes involve many steps of material deposition, patterning, and removal to form integrated circuits on a substrate. Different methods can be used to deposit a film of material on a substrate. For example, chemical vapor deposition (CVD) involves exposing a substrate to a continuous flow of precursor gases. These precursor gases react to form a film on the substrate. 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 of the problems mentioned in any part of this disclosure.

[0003] Disclosed examples relate to controlling a growth profile of a silicon-containing film deposited on features of a substrate. One example provides a method of performing a cyclic chemical vapor deposition (CVD) / etch process to control a profile of a silicon-containing film deposited on a substrate containing spacer structures. Each spacer structure contains a top field and one or more sidewalls. The method contains performing a plurality of alternating CVD steps and etch steps. Each CVD step contains depositing a portion of the silicon-containing film on the spacer structures of the substrate. Each etch step contains forming a plasma with a gas mixture containing a halogen-containing etchant to adjust the profile of the silicon-containing film.

[0004] In some such examples, each CVD step is a plasma-enhanced CVD (PECVD) step that contains forming a plasma with a gas mixture containing one or more film precursors and an inert gas to deposit the portion of the silicon-containing film, and the profile contains vertical growth of the silicon-containing film on the top field of each spacer structure.

[0005] In some such examples, forming the plasma containing the one or more film precursors additionally or alternatively contains forming a continuous wave plasma.

[0006] In some such examples, the one or more film precursors additionally or alternatively contains a silicon-containing precursor, molecular nitrogen, and molecular hydrogen.

[0007] In some such examples, each PECVD step is additionally or alternatively performed at a first pressure of 0.1 to 3 Torr and each etch step is performed at a second pressure that is greater than the first pressure.

[0008] In some such examples, each etching step additionally or alternatively further comprises reducing a pressure from the second pressure to the first pressure, and flowing the halogen-containing etchant while reducing the pressure.

[0009] In some such examples, the controlled profile additionally or alternatively comprises conformal growth on the top field region and the one or more sidewalls of each spacer structure.

[0010] In some such examples, each CVD step is a PECVD step comprising forming a plasma with a gas mixture comprising one or more film precursors and an inert gas to deposit the portion of the silicon-containing film.

[0011] In some such examples, forming the plasma comprising the one or more film precursors additionally or alternatively comprises pulsing the plasma.

[0012] In some such examples, the one or more film precursors additionally or alternatively comprise a silicon-containing precursor and ammonia.

[0013] In some such examples, additionally or alternatively, each PECVD step is performed at a first pressure of 4 Torr to 20 Torr and each etching step is performed at a second pressure equal to or less than the first pressure.

[0014] In some such examples, the silicon-containing film additionally or alternatively comprises silicon nitride.

[0015] In some such examples, the silicon-containing film additionally or alternatively comprises one of silicon oxide, silicon oxynitride, silicon carbide, silicon oxycarbide, silicon carbonitride, or silicon oxycarbonitride.

[0016] Another example provides a plasma-enhanced chemical vapor deposition (PECVD) tool. The PECVD tool includes a process chamber, a substrate support disposed in the process chamber, and a radio frequency power supply configured to supply radio frequency power to form a plasma in the process chamber. The PECVD tool also includes flow control hardware configured to control gas flow from a film precursor source, an inert gas source, and an etchant chemical source into the process chamber. The PECVD tool also includes a controller configured to perform a plurality of alternating deposition steps and etching steps. The controller is configured to operate the flow control hardware to flow a silicon-containing film precursor from the film precursor source and an inert gas from the inert gas source into the process chamber in a deposition step. The controller is also configured to operate the radio frequency power supply to form a plasma including the silicon-containing film precursor and the inert gas in conditions configured to deposit a silicon-containing film on spacer structures of a substrate supported by the substrate support, each spacer structure including a top field region and one or more sidewalls. The controller is also configured to operate the flow control hardware to flow a halogen-containing etchant chemical from the etchant chemical source into the process chamber in an etching step. The controller is also configured to operate the radio frequency power supply to form a plasma including the halogen-containing etchant chemical in conditions configured to etch the silicon-containing film in the etching step.

[0017] In some such examples, the controller is configured to perform an etching step with one or more of a longer duration or a higher partial pressure than a previously performed etching step in the plurality of etching steps.

[0018] In some such examples, the controller is additionally or alternatively configured to operate the flow control hardware and an exhaust system of the PECVD tool to maintain a pressure of 0.1 to 3 Torr and to operate the radio frequency plasma to form a continuous wave plasma to deposit the silicon-containing film in vertical growth on the top field regions of the spacer structures during a deposition step.

[0019] Another example provides a method of performing plasma-enhanced chemical vapor deposition (PECVD) to control vertical growth of a silicon-containing film on a substrate comprising spacer structures. Each spacer structure comprises a top field region and one or more sidewalls. The method comprises performing one or more cycles of alternating deposition steps and etching steps to deposit the silicon-containing film on the spacer structures of the substrate. Each deposition step comprises forming a plasma with a gas mixture comprising a silicon-containing film precursor, a nitrogen-containing film precursor, hydrogen, and an inert gas to deposit the silicon-containing film on the spacer structures. Each etching step comprises forming a plasma with a gas mixture comprising a halogen-containing etchant to etch the silicon-containing film, thereby causing the silicon-containing film to grow at a faster growth rate on the top field region of each spacer structure than on the one or more sidewalls of each spacer structure.

[0020] In some such examples, the method further comprises, while performing the plurality of alternating deposition steps and etching steps, decreasing a duration of a subsequent deposition step and increasing a duration of a subsequent etching step.

[0021] In some such examples, additionally or alternatively, each deposition step is performed at a first pressure and each etching step is performed at a second pressure that is greater than the first pressure, and each etching step further comprises flowing the halogen-containing etchant while reducing the pressure from the second pressure to the first pressure.

[0022] In some such examples, forming the plasma in a subsequent deposition step of the plurality of deposition steps additionally or alternatively comprises forming a plasma further comprising a residual halogen-containing etchant from a previous etching step. BRIEF DESCRIPTION OF DRAWINGS

[0023] FIGS. 1A-1G schematically illustrate exemplary vertical growth of a film on a top field region of a spacer structure with alternating deposition steps and etching steps.

[0024] FIG. 2 schematically illustrates a concentration gradient of adsorbed halogen- containing etchant on a spacer structure of a substrate.

[0025] FIG. 3 illustrates a flowchart of an exemplary cyclical CVD / etching process comprising alternating deposition steps and etching steps.

[0026] FIGS. 4A-4G schematically illustrate an example of conformal growth of a film on a spacer structure with alternating deposition steps and etching steps.

[0027] Figure 5 shows a flowchart of an exemplary cyclical CVD / etch process that includes alternating long duration deposition steps and long duration etch steps, followed by alternating short duration deposition steps and short duration etch steps.

[0028] Figures 6A-6B show a flowchart of an exemplary method for performing a cyclical CVD / etch process for controlling the profile of a silicon-containing film deposited on a spacer structure.

[0029] Figure 7 schematically shows an exemplary PECVD tool.

[0030] Figure 8 shows a block diagram of an exemplary computing device. DETAILED DESCRIPTION

[0031] The term "chemical vapor deposition (CVD)" generally represents a process in which a solid phase film is formed on a substrate by directing a continuous flow of one or more precursor gases over the substrate surface under conditions configured to cause film formation. Plasma enhanced chemical vapor deposition (PECVD) utilizes plasma to facilitate film formation.

[0032] The term "conformal film" generally represents a film having a uniform thickness over the substrate surface in different directions.

[0033] The term "deposition step" generally represents a portion of a cyclical PECVD / etch process in which a film is deposited on a substrate.

[0034] The term "etch step" generally represents a portion of a cyclical PECVD / etch process in which portions of a film previously deposited in a deposition step are removed to alter the profile of the film.

[0035] The term "flow control hardware" generally represents components that fluidly connect one or more chemical sources to a process chamber. For example, flow control hardware can include: conduits, mass flow controllers, and / or valves.

[0036] The term "gap" generally represents a recess in a substrate surface.

[0037] The term "halogen-containing etchant" generally represents a chemical used in an etching process to chemically remove material from a substrate or to facilitate the chemical removal of material. Examples include: fluorine-containing etchants, chlorine-containing etchants, and bromine-containing etchants. Exemplary fluorine-containing etchants include: F2, HF, BF3, PF3, NF3, fluorochlorocarbons, fluorocarbons, hydrofluorocarbons, chalcogen fluorides such as SF4and SF6, and interhalogen compounds such as CIF3and CIF5. Exemplary fluorocarbons include: CF4and C2F6. Examples of chlorine-containing etchants include: HCI, Cl2, and chalcogen chlorides such as S2CI2or SCI2. Examples of bromine-containing etchants include HBr and Br2. The term "interhalogen compound" generally represents a molecule that includes two or more different halogen atoms.

[0038] The term "cyclic CVD / etch process" generally represents a process that includes one or more cycles, each cycle including a CVD step and an etch step.

[0039] The term "plasma" generally represents a gas that includes cations and free electrons. The term "capacitively coupled plasma" generally represents a plasma formed between a pair of capacitive electrode plates. Exemplary capacitive electrode plates can include a showerhead electrode plate and a pedestal electrode plate. The term "inductively coupled plasma" generally represents a plasma formed using an electric field generated by an induction coil.

[0040] The term "processing chamber" generally represents an enclosure in which chemical and / or physical processing is performed on a substrate. The pressure, temperature, and atmospheric composition in a processing chamber are controllable to perform chemical and / or physical processing.

[0041] The term "processing tool" generally represents a machine that includes a processing chamber and other hardware configured to perform processing of a substrate.

[0042] The term "cleaning" and variants thereof generally represents a process that removes unwanted material from a processing chamber.

[0043] The term "silicon-containing film" generally represents a layer of material that includes silicon and is located on an underlying substrate. Silicon-containing films can be deposited using CVD. Exemplary silicon-containing films include: films including silicon nitride, silicon oxide, silicon carbide, silicon oxycarbide, silicon oxynitride, silicon nitrocarbide, and silicon oxynitrocarbide.

[0044] The term "silicon-containing precursor" generally represents any material that can be introduced in a gas phase into a processing chamber to form a silicon-containing film on a substrate. Exemplary film precursors that form silicon-containing films using CVD can include materials having the following general structure: where R1, R2, and R3may be the same or different substituents. In various examples, R1, R2, and R3may include: silanes; amines; halides; hydrogen; or organic groups such as alkylamines, alkyls, alkenyls, alkynyls, and cyclic groups (e.g., aromatic groups).

[0045] In some examples, the silicon-containing precursor is an alkoxysilane. Alkoxysilanes that can be used include compounds having the general formula: H x -Si-(OR) y where x = 1 to 3, x + y = 4, and each R is a substituted or unsubstituted aliphatic or aromatic group; and H x (RO) y -Si-Si-(OR) y H x where each R is a substituted or unsubstituted aliphatic or aromatic group. Exemplary alkoxysilanes include: tetramethyloxysilane (TMOS), diethoxymethylsilane (DEMS), diethoxysilane (DES), dimethoxymethylsilane, dimethoxysilane (DMOS), methyldiethoxysilane (MDES), methyldimethoxysilane (MDMS), t-butoxydisilane (MDMS), triethoxysilane (TES), and trimethoxysilane (TMS or TriMOS).

[0046] In some examples, the silicon-containing precursor can be a siloxane. Siloxanes include materials having Si-O-Si linkages. Exemplary siloxanes include: octamethylcyclotetrasiloxane (OMCTS), octamethyldodecasiloxane (OMODDS), and tetramethylcyclotetrasiloxane (TMCTS).

[0047] In some examples, the silicon-containing precursor is an aminosilane. Aminosilanes include materials having the general formula: H x -Si-(NR) y where x = 1 to 3, x + y = 4, and R is a substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aromatic, or hydride group. Exemplary aminosilanes include: bisdiethylaminosilane, diisopropylaminosilane, bis(tert-butylamino)silane (BTBAS), di-sec-butylaminosilane, and tris(dimethylamino)silane (3DMAS).

[0048] In some examples, the silicon-containing precursor is a halosilane. Halosilanes can also be referred to as halogenated silanes. In some examples, halosilanes include at least one hydrogen atom. Such silanes can have the general formula SiX aH y where y > 1. Exemplary halosilanes include: dichlorosilane (H2SiCl2), hexachlorodisilane (Si2Cl6), and diiodosilane (H2SiI 2) .

[0049] More specific examples of silicon-containing precursors include silane (SiH4) and polysilane (Si n H 2n+2 where n > 1, such as disilane, trisilane, and tetrasilane), trisilazane, tetraethyl orthosilicate (TEOS), monosilane, trimethylsilane (3MS), disilane, butylsilane, pentasilane, octasilane, heptasilane, hexasilane, cyclobutylsilane, cycloheptasilane, cyclohexylsilane, cyclooctasilane, cyclopentasilane, l,4-dioxa-2,3,5,6-tetrasilacyclohexane, triethoxysilane (TRIES), and tetramethylorthotetrasiloxane (TOMCTS).

[0050] Exemplary carbon-containing precursors for forming silicon carbide and other silicon-containing films can include alkanes, alkenes, alkynes, cyclic hydrocarbons, aromatic hydrocarbons, haloalkanes, alkylamines, and alkyl diamines. In some examples, the carbon-containing precursor can include an alkane having the general formula C n H 2n+2 where n = 1 to 10. Examples of suitable alkanes can include: methane, ethane, propane, butane, pentane, hexane, and substituted alkanes. Examples of suitable alkenes (for alkenes having a single carbon-carbon double bond, C n H 2n where n = 2 to 10) can include: ethylene, propylene, and butylene. Examples of suitable alkynes (for alkynes having a single carbon-carbon triple bond, C n H 2n-2 where n = 2 to 10) can include: acetylene, propyne, and butyne. Examples of suitable cyclic hydrocarbons can include: cyclobutene, cyclopentane, and cyclohexane. Examples of suitable aromatic hydrocarbons can include: benzene, toluene, pyridine, and pyrimidine. Examples of suitable haloalkanes can include: fluoroethane, 2-bromopropane, and chloro-tert-butane. Suitable alkylamines can include: methylamine, dimethylamine, trimethylamine, and piperidine. Suitable alkyl diamines can include: ethylenediamine, and 1,3- propanediamine. In other examples, the carbon-containing precursor can include a mixture of carbon-containing precursors.

[0051] Exemplary nitrogen-containing precursors for forming silicon nitride films can include ammonia (NH3) and aminosilane. Examples of aminosilanes include those described above.

[0052] An exemplary precursor to provide nitrogen for the formation of silicon oxynitride films is N2O.

[0053] The term "spacer structure" generally represents a feature that is recessed from, or extends from, the surrounding substrate surface on a substrate, and is spaced apart from one another.

[0054] The term "substrate" generally represents any object on which a film can be deposited.

[0055] The term "showerhead" generally represents a process gas outlet that includes a plurality of spatially distributed outlet holes for directing process gas to a substrate surface.

[0056] The term "substrate support" generally represents any structure used to support a substrate in a processing chamber during substrate processing. An example substrate support is a susceptor.

[0057] The term "sidewall" generally represents a surface of a spacer structure that extends at least partially upward or downward from a surface plane of a substrate.

[0058] The term "top field" generally represents a highest portion of a feature of a substrate. In some examples, a top field can generally have a planar structure. Example top fields include a top surface of a pillar and a substrate top surface between gaps.

[0059] As described above, electronic device manufacturing can include deposition processes and etching processes for forming structures on a substrate. For example, an etching process can be performed to remove material from gaps. To avoid damaging a top field between adjacent gaps, a patterned hard mask can be formed on the top field. However, forming a patterned hard mask can involve a time-consuming photolithographic patterning process. An example hard mask fabrication process can first involve deposition of a hard mask layer. Example hard mask layers can include silicon nitride, silicon oxide, silicon carbide, silicon oxynitride, silicon oxycarbide, silicon oxycarbonitride, and silicon oxycarbonitride. The hard mask formation process can further involve deposition of a photoresist layer over the hard mask layer. The photoresist layer is then exposed and developed. Next, an initial etching step is performed to remove regions of the hard mask that are not protected by the photoresist. This forms a patterned hard mask. Next, the remaining photoresist is removed. Then, an etching can be performed on the gaps. The patterned hard mask protects the top field between the gaps during the etching. Finally, the patterned hard mask is removed. Such hard mask fabrication and processing can add significant time and cost to substrate processing.

[0060] Deposition of conformal films on spacer structures can also be challenging. Atomic layer deposition (ALD) can be used to form a conformal film on a substrate in a layer-by-layer fashion using one or more ALD cycles. In an ALD cycle, a film precursor is adsorbed onto the surface of a substrate disposed in a processing chamber. Excess film precursor is purged from the processing chamber. The adsorbed film precursor is then chemically transformed into a film on the substrate. Next, another purge step is performed before more film precursor is directed to the processing chamber. One or more deposition cycles can be used to grow a highly conformal film of a target thickness. However, ALD can be relatively slow because each ALD cycle deposits a thin film layer. ALD processing can include tens to hundreds of ALD cycles to grow a film. Faster deposition techniques, such as CVD, tend to grow non-conformal films. More specifically, CVD tends to deposit thicker films on the top of a recessed structure than on the bottom of a recessed feature. Thus, CVD films can form a bread-loaf profile on the top field region of a spacer structure that varies with depth. In addition, CVD films can be thinner at a deeper location in a recessed feature than at the opening of the recessed feature. This can result in the formation of voids because film growth near the top of the feature can cause the opening to close.

[0061] Accordingly, disclosed examples involve using a cyclical CVD / etch process to control the profile of a silicon-containing film deposited on spacer structures by CVD. These spacer structures can include recessed features and / or protruding features. Each spacer structure includes a top field region and one or more sidewalls. Each deposition step of a CVD / etch cycle forms a layer of the silicon-containing film on the spacer structures. As noted above, CVD tends to form a non-conformal, bread-loaf profile film on the top of a spacer structure. Accordingly, each etch cycle is used to adjust the profile of the silicon-containing film. In addition, as described in more detail below, the etch gas mixture will include one or more process gases that have an inhibiting effect on the next deposition step. The etch conditions can be controlled to adjust the inhibiting effect by controlling the concentration profile of the inhibiting molecules on the surface of the substrate, particularly on the sidewall surfaces of the spacer structures. Depending on the conditions used, the cyclical deposition and etching can provide vertical growth on the top field region of the spacer structures, or conformal growth on all surfaces of the spacer structures. In addition, the cyclical CVD / etch process can be performed using less expensive precursors (e.g., silane) than ALD. Accordingly, disclosed examples can save costs in conformal deposition of silicon-containing films. The process conditions that can be controlled to obtain a desired profile of the silicon-containing film can include substrate temperature, total pressure in the processing chamber, partial pressure of each of the one or more gases, gas flow rate, gas flow duration, deposition step duration, and / or etch step duration.

[0062] To achieve vertical growth of the silicon-containing film on the top field regions of the various spacer structures, the silicon-containing film can be deposited using capacitively coupled plasma and using PECVD. As discussed in more detail below, performing PECVD at a relatively lower total pressure can help achieve a relatively higher degree of vertical growth as compared to performing PECVD at a relatively higher total pressure. This is because there are fewer collisions in the path to the substrate surface as the total pressure of ionized precursor molecules is lowered. This allows for more deposition in the vertical direction. Using a relatively heavier inert gas (e.g., argon instead of helium) in the PECVD process can also help achieve vertical growth. This is because the inert gas atoms can sputter the silicon-containing film as it grows. Because there is a higher film growth rate in the vertical direction as compared to the horizontal direction in a relatively lower pressure environment, sputtering of lower growth rate surfaces (e.g., the sidewalls of the spacer structures) can inhibit growth on these surfaces. In contrast, the film growth on higher growth rate surfaces can more significantly outpace the etching effect of the inert gas atoms. This can result in a greater net vertical growth. Additional shaping can then be performed in an etching step performed after the deposition step. Furthermore, a halogen-containing etchant can be used in the etching step. At the beginning of the deposition step, at least some residual halogen-containing etchant can remain in the processing chamber. This can provide an inhibition effect that inhibits deposition. This can further reduce film growth on the sidewalls due to the lower film deposition rate on the sidewalls as compared to the top field regions. Furthermore, hydrogen gas can be used in the PECVD step to achieve an additional inhibition effect. This can further help avoid silicon-containing film growth on the sidewalls of the spacer structures.

[0063] The vertical growth of the silicon-containing film disclosed herein can be used to form a hardmask without lithographic patterning. In some such examples, the silicon-containing film can be grown vertically on the hardmask partway through an etching process. This can allow for the use of a thinner initial hardmask. The use of a thinner hardmask layer can provide more accurate pattern transfer as compared to the use of a thicker initial hardmask layer. Furthermore, the vertical growth of the silicon-containing film disclosed herein can also avoid the time and expense of performing a lithographic process to pattern the hardmask.

[0064] A cyclic CVD / etch process can also be controlled to grow a conformal silicon-containing film on these spacer structures. In such examples, the deposition step of the cyclic CVD / etch process can be performed to deposit a silicon-containing film using any suitable CVD method. Examples include thermal CVD and PECVD. Furthermore, during CVD, the deposition step can be performed using a relatively higher total pressure than used for vertical growth. For example, in a PECVD step, the use of a higher pressure reduces the directional etching effect of the inert gas. In some examples, the PECVD step can include a pulsed plasma. Compared to a continuous wave plasma, a pulsed plasma results in a relatively lower ion energy. Due to the lower ion energy, there can be a larger ion impact angle distribution on the sidewall surfaces. As a result, a relatively larger amount of film forming species can be deposited on these sidewall surfaces compared to a continuous wave plasma. This helps to grow a thicker silicon-containing film on the sidewall surfaces. The lower ion energy can also result in less sidewall sputtering. Furthermore, sidewall etching can be further reduced by pulsing the plasma during the deposition step. Furthermore, ammonia can be used instead of hydrogen during PECVD. This can help to reduce the inhibition of film growth on the sidewalls compared to the use of hydrogen. By increasing the sidewall deposition rate and reducing sidewall inhibition and etching effects, such process conditions can help to achieve conformal growth of a silicon-containing film.

[0065] Furthermore, film growth on the upper sidewall surfaces and the top field region of the spacer structures can be faster than film growth on other surfaces. However, the etch step can remove material from such upper sidewall surfaces and top field region surfaces to result in a more conformal film. This is because during the etch step of the cyclic CVD / etch process, reactive ions in the plasma preferentially adsorb onto and etch the upper sidewall surfaces and the top field region. For example, using NF3to form a capacitively coupled plasma, F ions are formed with an upward velocity (a velocity perpendicular to the substrate). When in contact with a substrate surface, these F ions react quickly to etch the silicon-containing film. Due to the upward velocity, these F ions are more likely to hit the top field region than the sidewall surfaces. Furthermore, these F ions have a stronger reactivity than F radicals. As a result, the F ions can react and / or decay before reaching the lower surfaces in the gap. Thus, the F ions preferentially etch the surfaces near the top of the spacer structure. By preferentially etching surfaces that have faster film growth, the cyclic CVD / etch process can be used to grow a silicon-containing film with a relatively high degree of conformality.

[0066] Although discussed in the context of silicon nitride films, the example cyclic CVD / etch processes disclosed herein can be applied to other films, such as silicon oxide films, silicon carbide films, silicon carbon oxide films, silicon oxynitride films, silicon carbon nitride films, and silicon carbon oxynitride films.

[0067] FIGS. 1A-1G schematically illustrate an example structure formed during a cyclic CVD / etch process for achieving vertical film growth on top field regions of spaced structures of a substrate 100. The cyclic CVD / etch process deposits the film using alternating deposition steps and etching steps. In the example depicted in FIGS. 1A-1G, the growth profile includes vertical growth on the top field regions of the spaced structures, while there is little film growth on the sidewalls of the spaced structures. The cyclic CVD / etch process can be performed, for example, in a processing chamber of a processing tool. An example processing tool is described below with reference to FIG. 7.

[0068] FIG. 1A shows a substrate 100 including three pillars 102, 103, 104. A gap 106 is between pillar 102 and pillar 103. Another gap 108 is between pillar 103 and pillar 104. Each pillar includes a top field region and sidewalls. For example, pillar 102 includes a top field region 112 and sidewalls 113A, 113B. A bottom field region 118 is at the bottom of gap 106 between pillars 102, 103.

[0069] FIG. 1B shows substrate 100 after a first deposition step 120 of depositing a portion of a silicon-containing film 122. First deposition step 120 deposits a vertically growing silicon-containing film 122 on the top field regions of the spaced structures. For example, as shown at 124, the deposited film is thicker on top field region 112 than on sidewall 113B and on bottom field region 118. Silicon-containing film 122 is also thicker near the top of the sidewalls. This forms so-called "bread loaf" structures 126, 127, 128 on pillars 102, 103, 104, respectively.

[0070] In depositing a silicon nitride film, first deposition step 120 can include forming a plasma using a gas mixture including a silicon-containing film precursor, molecular nitrogen (N2), molecular hydrogen (H2), and an inert gas. Using a molecular hydrogen gas in the process gas mixture can reduce the amount of silicon incorporated into the film and increase the stability of the film. Hydrogen can also reduce the growth rate due to an inhibition effect, as discussed in more detail below. One example of a silicon-containing film precursor is silane. In particular, the use of silane can save costs compared to the use of more expensive precursors used in some ALD processes.

[0071] Other examples of silicon-containing film precursors include alkoxysilanes. Alkoxysilanes that can be used include compounds having the general formula H x -Si-(OR) y where x = 1 to 3, x + y = 4, and each R is a substituted or unsubstituted aliphatic or aromatic group; and compounds having the general formula H x (RO) y -Si-Si-(OR)y H x , wherein each R is a substituted or unsubstituted aliphatic or aromatic group. Exemplary alkoxysilanes include: tetramethoxysilane (TMOS), diethoxymethylsilane (DEMS), diethoxysilane (DES), dimethoxymethylsilane, dimethoxysilane (DMOS), methyldiethoxysilane (MDES), methyldimethoxysilane (MDMS), t-butoxydisilane, triethoxysilane (TES), and trimethoxysilane (TMS or TriMOS).

[0072] Further examples of silicon-containing precursors include siloxanes. Siloxanes include materials having Si-O-Si linkages. Exemplary siloxanes include: octamethylcyclotetrasiloxane (OMCTS), octamethoxydodecasiloxane (OMODDS), and tetramethylcyclotetrasiloxane (TMCTS).

[0073] Other silicon-containing precursors include aminosilanes. Aminosilanes include materials having the general formula: x -Si-(NR) y wherein 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, or hydride group. Exemplary aminosilanes include: bisdiethylaminosilane, diisopropylaminosilane, bis(tert-butylamino)silane (BTBAS), di-sec-butylaminosilane, and tris(dimethylamino)silane (3DMAS).

[0074] Further examples of silicon-containing precursors include halosilanes. In some examples, halosilanes can include at least one hydrogen atom. Such silanes can have the general formula SiX a H y wherein y > 1. Exemplary halosilanes can include: dichlorosilane (H2SiCl2), hexachlorosilane (Si2Cl6), and diiodosilane (H2SiI 2) .

[0075] Other examples of silicon-containing precursors include polysilanes (Si n H 2n+2where n > 1, e.g., disilane, trisilane, and tetrasilane), trisilazane, tetraethyl orthosilicate (TEOS), monosilane, trimethylsilane (3MS), disilane, butylsilane, pentasilane, octasilane, heptasilane, hexasilane, cyclobutylsilane, cycloheptylsilane, cyclohexylsilane, cyclooctylsilane, cyclopentylsilane, l,4-dioxa-2,3,5,6-tetrasilacyclohexane, triethoxysilane (TRIES), and tetramethylorthocyclotetrasiloxane (TOMCTS).

[0076] Examples of suitable inert gases include: argon, helium, neon, krypton, and xenon. The use of relatively heavy inert gases, such as Ar, can help sputter the sidewall portions of the pillars 102, 103, 104 and reduce the growth rate of the silicon-containing film 122 on such surfaces, as compared to the use of helium. This can help achieve a vertical growth profile.

[0077] As noted above, in some examples, the silicon-containing film includes carbon. Examples of such silicon-containing films include: silicon carbide, silicon oxycarbide, silicon carbonitride, and silicon oxycarbonitride. Examples of carbon-containing precursors for forming such films include: alkanes, alkenes, alkynes, cyclic hydrocarbons, aromatic hydrocarbons, haloalkanes, alkylamines, and alkyl diamines. In some examples, the carbon-containing precursor can include an alkane having the general formula CnH2n+2, where n = 1 to 10. Examples of suitable alkanes can include: methane, ethane, propane, butane, pentane, hexane, and substituted alkanes. Examples of suitable alkenes (for alkenes having a single carbon-carbon double bond, CnH2n) can include: ethylene, propylene, and butylene. Examples of suitable alkynes (for alkynes having a single carbon-carbon triple bond, CnH2n) can include: acetylene, propyne, and butyne. Examples of suitable cyclic hydrocarbons can include: cyclobutene, cyclopentane, and cyclohexane. Examples of suitable aromatic hydrocarbons can include: benzene, toluene, pyridine, and pyrimidine. Examples of suitable haloalkanes can include: fluoroethane, 2-bromopropane, and chloro-tert-butane. Examples of suitable alkylamines can include: methylamine, dimethylamine, trimethylamine, and piperidine. Examples of suitable alkyl diamines can include: ethylenediamine, and 1,3-propanediamine. In other examples, the carbon-containing precursor can include a mixture of carbon-containing precursors. n H 2n+2 where n = 1 to 10. Examples of suitable alkanes can include: methane, ethane, propane, butane, pentane, hexane, and substituted alkanes. Examples of suitable alkenes (for alkenes having a single carbon-carbon double bond, CnH2n) where n = 2 to 10) can include: ethylene, propylene, and butylene. Examples of suitable alkynes (for alkynes having a single carbon-carbon triple bond, CnH2n) where n = 2 to 10) can include: acetylene, propyne, and butyne. Examples of suitable cyclic hydrocarbons can include: cyclobutene, cyclopentane, and cyclohexane. Examples of suitable aromatic hydrocarbons can include: benzene, toluene, pyridine, and pyrimidine. Examples of suitable haloalkanes can include: fluoroethane, 2-bromopropane, and chloro-tert-butane. Examples of suitable alkylamines can include: methylamine, dimethylamine, trimethylamine, and piperidine. Examples of suitable alkyl diamines can include: ethylenediamine, and 1,3-propanediamine. In other examples, the carbon-containing precursor can include a mixture of carbon-containing precursors. n H 2n where n = 2 to 10) can include: ethylene, propylene, and butylene. Examples of suitable alkynes (for alkynes having a single carbon-carbon triple bond, CnH2n) where n = 2 to 10) can include: acetylene, propyne, and butyne. Examples of suitable cyclic hydrocarbons can include: cyclobutene, cyclopentane, and cyclohexane. Examples of suitable aromatic hydrocarbons can include: benzene, toluene, pyridine, and pyrimidine. Examples of suitable haloalkanes can include: fluoroethane, 2-bromopropane, and chloro-tert-butane. Examples of suitable alkylamines can include: methylamine, dimethylamine, trimethylamine, and piperidine. Examples of suitable alkyl diamines can include: ethylenediamine, and 1,3-propanediamine. In other examples, the carbon-containing precursor can include a mixture of carbon-containing precursors. n H 2n-2 where n = 2 to 10) can include: acetylene, propyne, and butyne. Examples of suitable cyclic hydrocarbons can include: cyclobutene, cyclopentane, and cyclohexane. Examples of suitable aromatic hydrocarbons can include: benzene, toluene, pyridine, and pyrimidine. Examples of suitable haloalkanes can include: fluoroethane, 2-bromopropane, and chloro-tert-butane. Examples of suitable alkylamines can include: methylamine, dimethylamine, trimethylamine, and piperidine. Examples of suitable alkyl diamines can include: ethylenediamine, and 1,3-propanediamine. In other examples, the carbon-containing precursor can include a mixture of carbon-containing precursors.

[0078] Oxygen-containing precursors for forming silicon oxide, silicon oxynitride, silicon oxycarbide, and silicon oxycarbonitride films can include: molecular oxygen, water, hydrogen peroxide, and nitrogen oxides (e.g., nitrous oxide).

[0079] The first deposition step 120 may include any suitable duration. In some examples, the first deposition step 120 includes a duration of 2-20 seconds; in other examples, durations outside this range may also be used. All ranges described herein include endpoints.

[0080] In some examples, the plasma can be formed using continuous-wave plasma. Continuous-wave plasma refers to plasma formed without adjusting the RF power. In other examples, pulsed plasma can be used. Pulsed plasma may be more advantageous for conformal film growth than vertical growth. This is because, as mentioned above, the relatively lower ion energy results in a larger ion impact angle distribution on the sidewall surfaces. Therefore, a relatively larger amount of film-forming material is deposited on these sidewall surfaces compared to continuous-wave plasma. This helps to grow a thicker silicon-containing film on the sidewall surfaces. Alternatively, the relatively lower energy of the inert gas ions in pulsed plasma may result in a smaller sputtering effect on the sidewall surfaces compared to continuous-wave plasma. Any suitable RF power can be used. Examples include RF power ranging from 50W to 6500W. Exemplary frequencies for RF plasma include 400kHz, 13.56MHz, 27MHz, 60MHz, and 90MHz. In some examples, two or more frequencies can be used simultaneously to form the plasma, as further described below. In some examples, capacitively coupled plasma can be formed by applying RF energy to either a nozzle or a base of a processing tool, with the other acting as a counter electrode. The use of capacitively coupled plasma allows for some control over the directionality of film growth by controlling the sputtering of an inert gas (e.g., argon) in the processing gas mixture onto the grown film. In other examples, inductively coupled plasma can be used.

[0081] The first deposition step 120 can be performed at any suitable substrate temperature and processing chamber pressure. Examples include temperatures from 50ºC to 650ºC and pressures from 0.1 to 3 Torr. Using relatively low pressure can enhance the sputtering effect of inert gas ions on the sidewall portions of sputtering pillars 102, 103, and 104 to deposit silicon-containing films. As mentioned above, this helps to achieve a faster film growth rate on the top field regions of pillars 102, 103, and 104 compared to the sidewalls. Therefore, a film with a vertical growth profile is deposited.

[0082] Flow control hardware can be used to control the flow rate and / or amount of various gases flowing into the processing chamber. In examples of forming silicon nitride films, the silicon-containing precursor can flow at a flow rate of 5-50 standard cubic centimeters (sccm) per minute. In some such examples, N2 can flow at a flow rate of 1000-5000 sccm. In some such examples, H2 can flow at a flow rate of 100-2500 sccm. Furthermore, in some other examples, the inert gas can flow at a flow rate of 1000-10000 sccm. In other examples, other flow rates can be used. The flow rate can depend on various factors such as pressure, temperature, and chamber size. Exemplary deposition steps are described in more detail below.

[0083] As described above, the breadstick structure can be formed during the first deposition step 120. Therefore, this cyclic CVD / etching process then includes a first etching step 130. Figure 1C shows the substrate 100 after the first etching step 130. The first etching step 130 includes forming a plasma using a gas mixture containing a halogen-containing etchant 132. This forms halide ions by the halogen-containing etchant 132. The plasma shapes the contour of the silicon-containing film 122 by etching the breadstick structures 126, 127, 128 of the silicon-containing film. Other portions of the silicon-containing film are also etched. For example, some of the silicon-containing film 122 on the top field regions and sidewalls of the pillars 102, 103, 104 are etched. As shown in Figure 1C, the sidewalls of the pillars 102, 103, 104 contain a thinner silicon-containing film 122 compared to the silicon-containing film 122 in Figure 1B, and in some examples, the silicon-containing film can be removed from these sidewalls. However, some of the silicon-containing film 122 remains on the top field regions of the pillars 102, 103, and 104. Therefore, the silicon-containing film 122 has a vertical growth profile.

[0084] The first etching step 130 can utilize any suitable halogen-containing etchant 132. Examples include: fluorine-containing etchants, chlorine-containing etchants, and bromine-containing etchants. Exemplary fluorine-containing etchants may include: F2, HF, BF3, PF3, NF3, chlorofluorocarbons, fluorocarbons, hydrofluorocarbons, sulfide fluorides such as SF4 or SF6, and interhalogen compounds such as ClF3 or ClF5. Example fluorocarbon compounds include: CF4 and C2F6. Examples of chlorine-containing etchants include: HCl, Cl2, and sulfide chlorides such as S2Cl2 or SCl2. Examples of bromine-containing etchants include: HBr and Br2. The term "interhalogen compound" generally refers to a molecule containing two or more different halogen atoms.

[0085] The first etching step 130 can be performed for any suitable duration. Examples include durations from 2 to 10 seconds. In other examples, etching step durations outside this range may also be used. Flow control hardware can be used to control the flow rate and / or amount of halogenated etchant flowing into the processing chamber during the first etching step 130. In some examples, the first etching step 130 causes the halogenated etchant 132 to flow at a flow rate of 100-300 sccm. Additionally, an inert gas can flow at a flow rate of 5000-30000 sccm. In other examples, flow rates outside this range may be used. Furthermore, the first etching step 130 can be performed at a pressure of 3-5 Torr. Therefore, in some examples, the first etching step 130 is performed at a higher pressure than the first deposition step 120.

[0086] After the plasma is formed in the first etching step 130, the processing chamber is purged. In some examples, partial purging is performed to leave some residual halogen-containing etchant in the processing chamber. This residual halogen-containing etchant has a suppressive effect on subsequent deposition steps. Due to the capacitively coupled plasma used in the next deposition step, the halogen-containing etchant can be adsorbed onto the sidewalls with a concentration gradient. Figure 2 schematically shows an example of halogen-containing etchant 132 adsorbed on pillars 102, 103, and 104. As shown in Figure 2, the concentration of halogen-containing etchant 132 adsorbed on the upper sidewall 210 is greater than the concentration of halogen-containing etchant 132 adsorbed on the lower sidewall 212. This can suppress silicon-containing film growth near the upper sidewall 210. Such suppression can reduce horizontal film growth that leads to breadcrumb structures.

[0087] The etchant concentration gradient along the sidewalls of pillars 102, 103, and 104 can be controlled by adjusting various processing conditions. Exemplary processing conditions include: total pressure of the processing chamber, partial pressure of the etchant, partial pressure of other gases (e.g., diluent gas), substrate temperature, gas flow rate, duration of the etchant gas flow, and plasma characteristics. For example, using capacitively coupled plasma to etch the silicon-containing film 122 can create a directional effect that drives the etchant into the gap. In some examples, the capacitively coupled plasma may contain a higher-frequency radio frequency energy component (“HF component”) and a lower-frequency radio frequency energy component (“LF component”). In some examples, the HF component may contain 50-6500 W of power. Increasing the power of the higher-frequency component can drive the halogen-containing etchant further into the gap. Additionally, in some examples, the LF component may also contain 0-6500 W of power. The use of the LF component can help drive the halogen-containing etchant deeper into the gap. Increasing the power of the LF component can further drive the halogen-containing etchant further into the gap. Therefore, the LF component can be adjusted to help remove the deposited film from deeper locations on the sidewalls. Furthermore, the LF component allows control over the surface on which adsorbed halogens act as inhibitors in the next deposition step.

[0088] Alternatively, after cleaning, the residual halogen-containing etchant 132 may be left in the processing chamber, and the halogen-containing etchant 132 may flow into the processing chamber after cleaning. For example, the halogen-containing etchant 132 may flow for a duration of 1-3 seconds. As described above, the deposition step can be performed at the first pressure and the etching step can be performed at a second pressure higher than the first pressure. In some such examples, the halogen-containing etchant may flow while the pressure is reduced from the second pressure to the first pressure.

[0089] Next, a second deposition step 140 is performed after the first etching step 130. As shown in FIG1D, the second deposition step 140 results in the additional growth of the silicon-containing film 122. In some examples, the second deposition step 140 may be performed using processing conditions similar to those of the first deposition step 120. In other examples, the second deposition step 140 may be performed using different processing conditions than those of the first deposition step 120. For example, the duration of the second deposition step 140 may differ from the duration of the first deposition step 120. Variations in step duration are discussed in more detail below with reference to FIG3.

[0090] The silicon-containing film 122 may also be included in the breadstick structure 142 formed during the second deposition step 140. However, as described above, the growth of the silicon-containing film 122 can be suppressed by halogen-containing etchant adsorbed on the sidewalls of the pillars 102, 103, and 104. Therefore, the breadstick structure 142 is farther from the substrate 100 than the breadstick structure depicted in FIG. 1B.

[0091] Next, a second etching step 150 is performed. In some examples, the second etching step 150 can be performed using processing conditions similar to those of the first etching step 130. In other examples, the second etching step 150 can be performed using processing conditions different from those of the first etching step 130. For example, the duration of the second etching step 150 may differ from that of the first etching step 130. The step duration is discussed in more detail below with reference to FIG3. As shown in FIG1E, this second etching step can etch the breadstick structure 142. Therefore, the silicon-containing film 122 is thicker in the top field region of the pillars 102, 103, and 104 compared to these sidewalls. In some examples, the sidewalls may be substantially free of silicon film 122.

[0092] Figure 1F shows the substrate 100 after the third deposition step 160. The third deposition step 160 can be performed using similar or different processing conditions as the first and / or second deposition steps. Finally, Figure 1G shows the substrate 100 after the third etching step 170. The third etching step 170 can be performed using similar or different processing conditions as the first and / or second etching steps. Due to the alternating deposition and etching steps, the silicon-containing film 122 includes a vertical growth profile.

[0093] As described above, the durations of the deposition and etching steps may vary during this cyclic CVD / etch process. Figure 3 shows a flowchart of an example cyclic CVD / etch process 300, which includes adjusting the step durations while performing alternating deposition and etching steps. The cyclic CVD / etch process 300 includes reducing the deposition step duration and increasing the etching step duration. This can help achieve a vertical growth profile of the deposited film. For example, as the silicon-containing film grows vertically, the gap volume between the spacer structures increases. Due to the increased gap volume, the gas concentration is relatively reduced. Therefore, the growth rate on the sidewall surfaces can be reduced relative to the film growth rate on the top field region. Similarly, the additional etching step duration allows the etchant to diffuse to the bottom of the gaps. Therefore, adjusting the deposition and etching step durations can help deposit a silicon-containing film with a vertical growth profile.

[0094] The cyclic CVD / etching process 300 includes a first cycle 302. The first cycle 302 includes a first deposition step 304 performed for a duration of j seconds. In some examples, 4 ≤ j ≤ 20. The first cycle 302 also includes a first etching step 306. In some examples, the first etching step may be performed for a duration of k seconds, where 2 ≤ k ≤ 10. In other examples, any other suitable duration may be used.

[0095] Next, the cyclic CVD / etching process 300 includes a second cycle 308. The second cycle 308 includes a second deposition step 310 performed for a duration of m seconds, where m < j. The second cycle 308 also includes a second etching step 312 performed for a duration of n seconds, where n > k. Therefore, from the first cycle 302 to the second cycle 308, the duration of the deposition step decreases and the duration of the etching step increases.

[0096] Next, the cyclic CVD / etch process 300 optionally includes an i-th cycle 314. The cyclic CVD / etch process 300 may include any suitable number of steps. The i-th cycle 314 includes an i-th deposition step 316 performed for a duration of p seconds, where p < m. The i-th cycle 314 also includes an i-th etching step 318 performed for a duration of q seconds, where q > n. Thus, from the second cycle 308 to the i-th cycle, the duration of the deposition step is further reduced and the duration of the etching step is further increased. In this way, the growth of the silicon-containing film on the sidewalls of the spacer structure can be more effectively suppressed in subsequent steps of the cyclic CVD / etch process 300. This can help achieve an improved vertical growth profile compared to an example with a constant step duration.

[0097] As described above, processing conditions can also be controlled to conformally grow silicon-containing films. Figures 4A-4G schematically show exemplary structures formed during a cyclic CVD / etch process, which includes alternating deposition and etching steps to deposit a conformal film on a spacer structure. For example, this cyclic CVD / etch process can be performed in the processing chamber of a processing tool. An exemplary processing tool is described below with reference to Figure 7.

[0098] As shown in Figure 4A, substrate 400 includes a spacer structure comprising three pillars 402, 403, and 404. A gap 406 is formed between pillars 402 and 403. Another gap 408 is formed between pillars 403 and 404. Each pillar includes a top field region and sidewalls. For example, pillar 402 includes a top field region 412 and sidewalls 413A and 413B. Furthermore, a bottom field region 418 is located at the bottom of gap 406 between pillars 402 and 403. This silicon-containing film can be conformally deposited on pillars 402, 403, and 404 by performing a cyclic CVD / etch process with alternating deposition and etching steps.

[0099] Figure 4B shows the substrate 400 after the first deposition step 420 for depositing the silicon-containing film 422. The first deposition step 420 deposits portions of the silicon-containing film 422 on the top surfaces and sidewalls of the pillars 402, 403, and 404. However, as shown in 424, the silicon-containing film 422 is thicker on the top field region 412 than on the sidewalls 413A and 413B. Furthermore, the silicon-containing film 422 is thicker near the top of these sidewalls. This forms breadcrumb structures 426, 427, and 428 on the pillars 402, 403, and 404, respectively.

[0100] The first deposition step 420 may involve forming a plasma using a gas mixture containing a silicon-containing film precursor, nitrogen (N2), ammonia (NH3), and an inert gas. Such a gas mixture can be used to deposit a silicon nitride film. As mentioned above, the presence of hydrogen in the gas mixture can improve the stability of the deposited silicon nitride film. Compared to the first deposition step 120 using hydrogen, using ammonia avoids some of the inhibitory effects of hydrogen on the sidewall surfaces. This can help to conformally grow the silicon-containing film 422 on the sidewalls. As mentioned above, in some examples, different CVD processes such as thermal CVD can be used to deposit this silicon-containing film.

[0101] Examples of silicon-containing film precursors include those listed above. In some examples, silicon-containing film precursors contain silanes, which can save costs compared to the more expensive precursors used in some ALD processes.

[0102] Examples of suitable inert gases include argon, helium, neon, krypton, and xenon.

[0103] As described above, in some examples, silicon-containing films may contain carbon. Examples of such silicon-containing films include silicon carbide, silicon oxycarbide, and silicon oxynitride. Examples of carbon-containing precursors used to form such films include those mentioned above. Oxygen-containing precursors used to form silicon oxide, silicon oxynitride, silicon oxycarbide, and silicon oxynitride films may contain molecular oxygen, water, hydrogen peroxide, and nitrogen oxides.

[0104] The first deposition step 420 can include any suitable duration. In some examples, the first deposition step 420 includes a duration of 10-300 seconds. However, durations outside this range are also possible. Gas can flow into the processing chamber for part or all of the deposition step duration. The first deposition step 420 can be performed at any suitable substrate temperature and processing chamber pressure. Examples include temperatures from 50°C to 650°C and pressures from 4 Torr to 20 Torr. The first deposition step 420 uses a relatively higher pressure compared to the first deposition step 120 used for vertical growth. This relatively higher pressure helps reduce the directional sputtering of inert gas ions in the plasma. Therefore, film growth on the sidewall surfaces can be improved. This can help with conformal growth of the silicon-containing film 422.

[0105] In some examples, the first deposition step 420 may use pulsed plasma. Pulsating this plasma, compared to continuous-wave plasma, helps form ions with relatively lower kinetic energy. As mentioned above, the relatively lower ion energy results in a larger ion impact angle distribution on the sidewall surfaces. Therefore, a relatively larger amount of film-forming material is deposited on these sidewall surfaces compared to continuous-wave plasma. This helps grow a thicker silicon-containing film on the sidewall surfaces. Furthermore, the lower ion energy reduces the sputtering effect of the plasma gas. Reduced sputtering allows for more sidewall growth, which helps in the conformal deposition of the silicon-containing film 422. Any suitable duty cycle can be used to pulse the plasma. Exemplary duty cycles include 5% to 50%. Additionally, any suitable radio frequency (RF) power can be used to form the plasma. Examples include 50W to 6500W of RF power. When using a second frequency, the RF power used for that second frequency can be 0 to 6500W. Exemplary frequencies for the RF plasma include 400kHz, 13.56MHz, 27MHz, 60MHz, and 90MHz. As mentioned above, in different examples, the plasma can be capacitively coupled or inductively coupled.

[0106] Flow control hardware can be used to control the flow rate and / or amount of various gases flowing into the processing chamber. The flow rate can depend on various factors, such as pressure, temperature, and chamber size. In some examples, the first deposition step 420 uses 100-300 ml of silicon-containing precursor, 200-500 ml of NH3, and 8-12 L of N2 at 5 Torr. In other examples, amounts outside these ranges can be used. In some examples, the processing chamber is purged after the first deposition step 420.

[0107] As described above, breadstick structures 426, 427, and 428 are formed during the first deposition step 420. Therefore, the subsequent cyclic CVD / etching process includes a first etching step 430. The first etching step 430 involves forming a plasma using a gas mixture containing a halogen-containing etchant 432. This plasma shapes the contour of the silicon-containing film 422 by etching the breadstick structures 426, 427, and 428. During the first etching step 430, reactive ions in the plasma are preferably adsorbed onto the upper sidewall surfaces and the top field region, and these surfaces are etched. This is because the reactive ions in the plasma have a shorter lifetime and react before reaching the deeper surfaces of the gaps 406 and 408. Therefore, the ion flux and etching rate are greater on the breadstick structures 426, 427, and 428 compared to other surfaces. By preferably etching surfaces with faster film growth, the first etching step 430 helps increase the conformability of the silicon-containing film 422. Other portions of the silicon-containing film 422 may also be etched. For example, some of the silicon-containing films 422 on the top field regions and sidewalls of the pillars 402, 403, and 404 are etched. As shown in FIG1C, the silicon-containing film 422 comprises a substantially uniform thickness on the top field regions and sidewalls of the pillars 102, 103, and 104. Therefore, the silicon-containing film 422 comprises a conformal profile.

[0108] The first etching step 430 can use any suitable halogen-containing etchant 432. As mentioned above, examples include: fluorine-containing etchants, chlorine-containing etchants, and bromine-containing etchants.

[0109] The first etching step 430 can be performed for any suitable duration. Examples include durations from 2 to 20 seconds. However, any suitable etching step duration outside this range may also be used. Flow control hardware can be used to control the flow rate and / or amount of the halogenated etchant flowing into the processing chamber during the first etching step 430. In some examples, the first etching step 430 causes the halogenated etchant 432 to flow at a flow rate of 100-300 sccm. Additionally, an inert gas may flow at a flow rate of 5000-30000 sccm. In other examples, flow rates outside these ranges may be used. Furthermore, the first etching step 430 can be performed at a pressure of 3 to 5 Torr. Therefore, the first etching step 430 can be performed at a lower pressure than the first deposition step 420.

[0110] After the etching process in the first etching step 430 is performed, the processing chamber can be cleaned.

[0111] Next, a second deposition step 440 is performed after the first etching step 430. As shown in FIG4D, the second deposition step 440 results in the growth of an additional silicon-containing film 422. In some examples, the second deposition step 440 can be performed using processing conditions similar to those of the first deposition step 420. In other examples, the second deposition step 440 can be performed using different processing conditions than those of the first deposition step 420. For example, the duration of the second deposition step 440 can be different from that of the first deposition step 420. Variations in step duration are described in more detail below with reference to FIG5.

[0112] The silicon-containing film 422 may also be included in the breadstick structure 442 formed during the second deposition step 440. However, the growth of the silicon-containing film 422 is inhibited by halogen-containing etchant adsorbed on the sidewalls of the pillars 402, 403, and 404. Therefore, the breadstick structure 442 is farther from the substrate 400 than the breadstick structure depicted in FIG. 4B.

[0113] Next, a second etching step 450 is performed. The second etching 450 can be performed using similar processing conditions as described above for the first etching step 430. In other examples, the second etching 450 can be performed using different processing conditions than the first etching step 430. For example, the duration of the second etching step 450 can be different from that of the first etching step 430. The step duration is discussed in more detail below with reference to FIG5. As shown in FIG4E, the second etching step can etch the breadstick structure 442. Therefore, the silicon-containing film 422 of FIG4E contains a thicker conformal film compared to the silicon-containing film of FIG4C.

[0114] Figure 4F shows the silicon-containing film 422 after the third deposition step 460. The third deposition step 460 can be performed using similar or different processing conditions as the first and / or second deposition steps. Finally, Figure 4G shows the silicon-containing film 422 after the third etching step 470. The third etching step 470 can be performed using similar or different processing conditions as the first and / or second etching steps. Compared to the silicon-containing film 122, the silicon-containing film 422 is grown conformally. Therefore, the silicon-containing film 422 of Figure 4G contains a thicker conformal film than the silicon-containing film of Figure 4E.

[0115] Therefore, using the above processing conditions, silicon-containing films 422 with conformal profiles can be grown. In experiments, deposition rates of 30 Å / s to 45 Å / s were achieved. The conformal conformity of the film can be represented by the ratio of the film thickness on the sidewalls of the spacer structure to the film thickness on the top field region of the spacer structure. Conformal conformity of 100% to 150% was achieved in experiments, measured by scanning transmission electron microscopy. In other examples, structures with non-vertical growth or conformal profiles can be formed by controlling the processing conditions used for cyclic CVD / etching.

[0116] As described above, in some examples, deposition and etching steps can be performed for different durations in different cycles. In some examples, the cyclic CVD / etch process may include long-duration steps in some cycles and short-duration steps in others. For example, the volume of gaps 406, 408 may be reduced due to the growth of the silicon-containing film 422. Therefore, conformally depositing additional film layers can be challenging. Therefore, the step durations can be adjusted to deposit relatively thick silicon-containing film layers in earlier steps and relatively thin silicon-containing film layers in later processing steps. This can help to conformally grow the silicon-containing film during later processing steps. Figure 5 shows a flowchart of an example cyclic CVD / etch process 500, which includes adjusting the step durations while performing alternating deposition and etching steps. The cyclic CVD / etch process 500 includes a first cycle 502. The first cycle 502 includes alternating first deposition step 504 and first etching step 506. In some examples, a first deposition step 504 can be performed for a duration of j seconds, where 120 ≤ j ≤ 240. In some examples, a first etching step 506 can be performed for a duration of k seconds, where 12 ≤ k ≤ 20. In other examples, any suitable duration can be used. As shown in 508, the first deposition step 504 and the first etching step 506 can be repeated M times, where M ≥ 1. In some more specific examples, 1 ≤ M ≤ 5.

[0117] After performing a first cycle 502 any suitable number M, the cyclic CVD / etching process 500 includes performing a second cycle 510. The second cycle 510 includes alternating second deposition steps 512 and second etching steps 514. In some examples, the second deposition step 512 may be performed for a duration of p seconds, where 1 / 2 ≤ p ≤ 20. In some examples, the second etching step 514 may be performed for a duration of q seconds, where 2 ≤ q ≤ 10. In other examples, any other suitable duration may be used. Therefore, each second deposition step 512 has a relatively short duration compared to the first deposition step 504 described above. Similarly, each second etching step 514 has a relatively short duration compared to the first etching step 506. As shown in 516, the second deposition step 512 and the second etching step 514 may be repeated N times, where N ≥ 1. In some more specific examples, 2 ≤ N ≤ 10. By utilizing a first cycle 502 and a subsequent second cycle 510, the cyclic CVD / etching process 500 can help deposit silicon-containing films conformally when gap shrinkage occurs due to film growth.

[0118] Figures 6A-6B show flowcharts of an exemplary method 600 for cyclic CVD / etching processes, which controls the profile of a silicon-containing film deposited on a spacer structure of a substrate. For example, method 600 can be performed using a processing tool to process a substrate disposed in a processing chamber of that tool.

[0119] Starting with Figure 6A, method 600 includes performing multiple alternating deposition and etching steps at 602. At 604, the deposition step includes depositing portions of the silicon-containing film on these spacer structures of the substrate.

[0120] In some examples, at 606, the deposition step includes a PECVD step, which involves forming a plasma using a gas mixture containing one or more film precursors and an inert gas to deposit a portion of the silicon-containing film. The profile includes the vertical growth of the silicon-containing film on the top field region of each spacer structure. In some such examples, the silicon-containing film is grown without horizontal growth on the sidewalls of these spacer structures. In some examples, at 608, step 606 is performed using a continuous-wave plasma. In other examples, pulsed plasma can be used. In some examples, at 610, the one or more film precursors include: a silicon-containing precursor, molecular nitrogen, and molecular hydrogen. Examples of suitable silicon-containing precursors are as described above. The addition of hydrogen to the gas mixture helps to form a plasma with enhanced etching effects on the sidewalls. This slows down the film growth rate on the sidewall surfaces and helps achieve a vertical growth profile. In some examples, additional precursors, such as carbon-containing and oxygen-containing precursors, can be used. Examples include those described above.

[0121] In some examples, at 612, method 600 includes performing the deposition step at a pressure of 0.1 to 3 Torr. As mentioned above, the sputtering etching effect of inert gas ions from this plasma can be enhanced at low pressure. This also helps to slow down the film growth rate on the sidewall surfaces.

[0122] In other examples, at 614, the profile includes conformal rather than vertical growth of the silicon-containing film on the top field region of each spacer structure and on one or more sidewalls. In other examples, the respective deposition steps are thermal CVD steps. In some examples, at 615, the respective deposition steps are PECVD steps, comprising forming a plasma using a gas mixture containing one or more film precursors and an inert gas to deposit portions of the silicon-containing film. In some such examples, at 616, method 600 includes pulsed plasma during the deposition step at 604. In some such examples, the plasma may be pulsed with a duty cycle of 5% to 50%, as described above. As described above, pulsed plasma can help deposit relatively thick films on the sidewall surfaces. In some examples, at 618, the one or more film precursors comprise: a silicon-containing precursor and ammonia. The use of ammonia helps reduce the etch effect of hydrogen on the film deposited on the sidewall surfaces. Examples of suitable silicon-containing precursors include those described above. In some examples, at 620, method 600 includes performing the deposition step at a pressure of 4 to 20 Torr. In other examples, pressures outside this range can be used. High pressure reduces the sputtering etch effect of the inert gas on the sidewall surfaces. By reducing etching at the sidewall surfaces at 616, 618, and / or 620, such examples help provide a more uniform growth rate of the silicon-containing film on the different surfaces of the spacer structure, which helps to provide conformal growth.

[0123] In some examples, at 622, the deposition step performed at 604 comprises depositing silicon nitride. In other examples, the deposition step may comprise depositing different silicon-containing films. Examples include: silicon oxide, silicon carbide, silicon carbide, silicon oxynitride, silicon carbide nitride, and silicon carbide nitride.

[0124] Continuing with Figure 6B, at 624, the etching step includes: forming a plasma using a gas mixture containing a halogen-containing etchant to shape the contour of the silicon-containing film. In some examples, capacitively coupled plasma is used to aid in the formation of halide ions from the halogen-containing etchant.

[0125] In an example including step 606, method 600 includes adjusting the profile of the silicon-containing film to a vertical growth profile. In some such examples, at 626, method 600 includes performing the deposition step at a first pressure greater than the first pressure and performing the etching step at a second pressure greater than the first pressure. In some such examples, at 628, performing the etching step includes reducing the pressure from the second pressure to the first pressure and allowing the halogen-containing etchant to flow. In this way, the halogen-containing etchant can suppress film growth on the sidewalls of these spacer structures during subsequent deposition steps.

[0126] In an example including step 614, method 600 includes adjusting the profile of the silicon-containing film to a conformal growth profile. In some such examples, at 630, method 600 includes performing the deposition step at a first pressure and performing the etching step at a second pressure, which is lower than the first pressure. As described above, performing the etching step at a relatively lower pressure than the deposition step helps to achieve conformal growth.

[0127] In some examples, forming the plasma at 632, 624 comprises forming the plasma under processing conditions configured to form a halide ion concentration gradient on one or more sidewalls of the respective spacer structures. The concentration gradient can provide a relatively greater inhibitory effect on film growth on the surface near the top of the spacer structure compared to the surface near the bottom of the spacer structure. In this way, the halide ion concentration gradient helps reduce breadcrumb formation.

[0128] Next, in some examples, at 634, the multiple alternating deposition and etching steps performed at 602 include: reducing the duration of subsequent deposition steps and increasing the duration of subsequent etching steps. Figure 3 shows an example of a reduced duration of subsequent deposition steps and an increased duration of subsequent etching steps. In some other examples, at 636, the multiple alternating deposition and etching steps performed at 602 include: reducing the duration of subsequent deposition steps and reducing the duration of subsequent etching steps. Figure 5 shows an example of a second step following a first step, which includes a shorter duration than the first steps.

[0129] Figure 7 schematically shows an exemplary processing tool 700 that can implement the examples described above according to Figures 1A-6B.

[0130] The processing tool 700 includes: a processing chamber 702; and a substrate support 704 located within the processing chamber. The substrate support 704 is configured to support a substrate 706 disposed within the processing chamber 702. The substrate support 704 may include a base, a chuck, and / or any other suitable structure. The substrate support 704 includes a substrate heater 708. In other examples, the heater may be omitted, or it may be located elsewhere within the processing chamber 702.

[0131] The processing tool 700 also includes a nozzle 710. In other examples, the processing tool may include a nozzle or other means for introducing gas into the processing chamber 702, rather than a nozzle or as a supplement to a nozzle. The processing tool 700 also includes flow control hardware 712. The flow control hardware 712 connects a processing gas source to the processing chamber. In the depicted example, the flow control hardware 712 connects a silicon-containing film precursor source 716, optionally a nitrogen-containing precursor source 718, optionally a hydrogen source 720, an inert gas source 722, and an etchant chemical source 724 to the processing chamber.

[0132] The silicon-containing membrane precursor source 716 contains any suitable precursor chemicals for forming the silicon-containing membrane. Exemplary silicon-containing membranes include membranes containing silicon nitride, silicon oxide, silicon carbide, silicon carbide, and silicon oxynitride. Example silicon-containing precursors include those described above. In some examples, the membrane precursor source may contain a mixture of chemicals. In other examples, two or more separate membrane precursor sources may be used to supply two or more corresponding membrane precursors.

[0133] Optionally, a carbon-containing precursor source (not shown) can be used to supply the carbon-containing precursor to form a silicon carbide film. Exemplary carbon-containing precursors include those described above. Furthermore, in some examples, an optional oxygen-containing precursor source can be used to supply the oxygen-containing precursor to form a silicon oxide, silicon oxynitride, silicon carbon oxide, or silicon oxynitride film. Examples of oxygen-containing precursors may include molecular oxygen, water, hydrogen peroxide, and nitrogen oxides.

[0134] Nitrogen precursor source 718 contains any suitable nitrogen-containing precursor. In some examples, nitrogen precursor source 718 contains NH3. In some examples, nitrogen precursor source 718 contains N2. In some examples, a combination of NH3 and N2 may be used. An exemplary precursor for providing nitrogen for the formation of a silicon oxynitride film is N2O. When included, hydrogen source 720 contains molecular hydrogen (H2). As described above, including H2 in the gas mixture of PECVD can increase the etching effect on the sidewall surfaces of the spacer structure and facilitate the vertical growth of the silicon-containing film. Alternatively, omitting H2 can help to grow the film conformally.

[0135] The inert gas source 722 may contain any suitable inert gas. Examples include: argon, helium, neon, krypton, and xenon.

[0136] Etching chemical source 724 may contain any suitable halogenated etchant chemicals. Examples include: fluorinated etchants, chlorinated etchants, and bromine-containing etchants. Exemplary fluorinated etchants may contain: F2, HF, BF3, PF3, NF3, chlorofluorocarbons, fluorocarbons, hydrofluorocarbons, sulfide fluorides such as SF4 and SF6, and interhalogen compounds such as ClF3 and ClF5. Exemplary fluorocarbons include: CF4 and C2F6. Examples of chlorinated etchants include: HCl, Cl2, and sulfide chlorides such as S2Cl2 or SCl2. Examples of bromine-containing etchants include: HBr and Br2.

[0137] The flow control hardware 712 may include any suitable components. Examples include mass flow controllers, valves, and conduits. For instance, the flow control hardware 712 may include one or more valves that control fluid connection between one or more selected gas sources and the nozzle 710. The flow control hardware 712 may also include one or more mass flow controllers or other controllers for controlling the mass flow rate of the gas.

[0138] The processing tool 700 also includes a venting system 732. The venting system 732 is configured to expel gases from the processing chamber 702. The venting system 732 may include any suitable hardware comprising one or more low-vacuum pumps and one or more high-vacuum pumps. Flow control hardware 712 and the venting system 732 may operate together to achieve a selected pressure in the processing chamber 702 during substrate processing.

[0139] The processing tool 700 also includes an RF power supply 734 electrically connected to the nozzle 710. The RF power supply 734 is configured to form a plasma using a gas mixture. For example, during a deposition step, the RF power supply 734 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, during an etching step, the RF power supply 734 can be operated to form a plasma using a gas mixture comprising a halogen-containing etchant to etch the silicon-containing film. In this example, the substrate support 704 is configured as a ground counter electrode. In other examples, the RF power supply 734 can supply RF power to the substrate support 704 or other suitable electrode structures. Thus, the RF power supply 734 forms a capacitively coupled plasma (CCP) during operation. Furthermore, the RF power supply 734 can be operated to pulse the plasma, for example, using any suitable duty cycle. Alternatively, the RF power supply 734 can form a continuous-wave plasma.

[0140] The processing tool 700 also includes a matching network 736 for impedance matching of the RF power supply 734. The RF power supply 734 can be configured to supply RF energy of any suitable frequency and power. Exemplary frequencies include 400 kHz, 13.56 MHz, 27 MHz, 60 MHz, and 90 MHz. In some examples, the RF power supply 734 is configured to operate at several different frequencies and / or powers. For example, as described above, the plasma may contain both low-frequency (LF) and high-frequency (HF) RF energy components. Examples of frequencies for the LF power component may include frequencies of 3 MHz and below. In some examples, the LF energy component may contain power from 0 to 6500 W. Examples of suitable high-frequency RF power include frequencies from 3 MHz to 300 MHz. In some examples, the HF RF energy component may contain power from 50 to 6500 W.

[0141] The processing tool 700 also includes a controller 750 configured to control the operation of the processing tool. The controller 750 is operatively coupled to a substrate heater 708, flow control hardware 712, an exhaust system 732, and an RF power supply 734. The controller 750 is configured to control various functions of the processing tool 700 to perform a CVD / etch cycle including deposition and etching steps. For example, the controller 750 is configured to operate the substrate heater 708 to heat the substrate to a desired temperature. The controller 750 is also configured to operate the flow control hardware 712 to allow selected gases or gas mixtures to flow into the processing chamber 702 at a selected rate. The controller 750 is further configured to operate the exhaust system 732 to remove gases from the processing chamber 702. The controller 750 may, for example, control the exhaust system 732 and / or the flow control hardware 712 to purge the processing chamber 702. The controller 750 is configured to operate the RF power supply 734 to form plasma and to control any other suitable functions of the processing tool 700. The controller 750 may include any suitable computing system. An exemplary computing system is described below with reference to FIG8.

[0142] Figure 8 schematically shows a non-limiting example of a computing system 800 capable of performing one or more of the methods and processes described above. The computing system 800 is shown in a simplified form. The computing system 800 may take the form of one or more personal computers, workstations, computers integrated with substrate processing tools, and / or network-accessible server computers.

[0143] The computing system 800 includes a logic machine 802 and a memory machine 804. The computing system 800 may optionally include a display subsystem 806, an input subsystem 808, a communication subsystem 810, and / or other components not shown in Figure 8. The controller 750 is an example of the computing system 810.

[0144] The logic machine 802 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 application programs, services, programs, routines, libraries, objects, components, data structures, or other logical constructs. Such instructions may be implemented to perform tasks, implement data types, transition the state of one or more components, achieve technical effects, or otherwise achieve desired results.

[0145] A logic machine may include one or more processors configured to execute software instructions. Additionally or alternatively, a logic machine may include one or more hardware or firmware logic machines configured to execute hardware or firmware instructions. The logic machine's processor may be single-core or multi-core, and the instructions executed on it may be configured for sequential, parallel, and / or distributed processing. The various components of the logic machine may optionally be distributed across two or more separate devices that can be remotely located and / or configured for coordinated processing. The various aspects of the logic machine can be virtualized and executed via remotely accessible, networked computing devices configured in a cloud computing configuration.

[0146] The storage device 804 includes one or more physical devices configured to store instructions 812, which are executable by a logic machine to implement the methods and processes described herein. When such methods and processes are implemented, the state of the storage device 804 can be transformed—for example, to store different data.

[0147] Storage device 804 may include removable and / or built-in devices. Storage device 804 may include optical storage (e.g., CD, DVD, HD-DVD, Blu-ray disc, etc.), semiconductor storage (e.g., RAM, EPROM, EEPROM, etc.) and / or magnetic storage (e.g., hard disk drive, floppy disk drive, magnetic tape drive, MRAM, etc.). Storage device 804 may include volatile, non-volatile, dynamic, static, read / write, read-only, random access, sequential access, location-addressable, file-addressable, and / or content-addressable devices.

[0148] It should be understood that the memory 804 includes one or more physical devices. However, alternatively, aspects of the instructions described herein may be propagated via a communication medium (e.g., electromagnetic signals, optical signals, etc.) that is not held by a physical device for a limited duration.

[0149] The logic unit 802 and the memory unit 804 can be integrated together into one or more hardware logic components. For example, such hardware logic components may include field-programmable gate arrays (FPGAs), program-specific and application-specific integrated circuits (PASICs / ASICs), program-specific and application-specific standard products (PSSPs / ASSPs), systems-on-a-chip (SoCs), and complex programmable logic devices (CPLDs).

[0150] When included, the display subsystem 806 can be used to present a visual representation of the data stored by the storage unit 804. This visual representation may take the form of a graphical user interface (GUI). Since the methods and processes described herein change the data held by the storage unit and thus change the state of the storage unit, the state of the display subsystem 806 can also be transformed to visually represent the changes in the underlying data. The display subsystem 806 may include one or more display devices using virtually any type of technology. Such display devices may be combined with the logic unit 802 and / or the storage unit 804 in a shared enclosure, or such display devices may be peripheral display devices.

[0151] When included, the input subsystem 808 may include or interact with one or more user input devices, such as a keyboard, mouse, or touchscreen. In some examples, the input subsystem may include or interact with a selected Natural User Input (NUI) component. Such components may be integrated or peripheral, and the translation and / or processing of input actions may be performed on-board or off-board. Exemplary NUI components may include a microphone for speech and / or voice recognition, and an infrared, color, stereo, and / or depth camera for machine vision and / or gesture recognition.

[0152] When included, the communication subsystem 810 can be configured to communicatively couple the computing system 800 to one or more other computing devices. The communication subsystem 810 may include wired and / or wireless communication devices compatible with one or more different communication protocols. As a non-limiting example, the communication subsystem may be configured to communicate using a wireless telephone network, or a wired or wireless local area network or wide area network. In some examples, the communication subsystem may allow the computing system 800 to send messages to and / or receive messages from other devices via a network such as the Internet.

[0153] It should be understood that the configurations and / or methods described herein are exemplary in nature, and these particular examples or illustrations should not be considered limiting, as many variations are possible. The specific routines or methods described herein may represent one or more of any number of processing strategies. Therefore, the various actions shown and / or described may be performed in the order shown and / or described, in another order, in parallel, or omitted. Similarly, the order of the above processing may be changed.

[0154] The subject matter of this disclosure includes all novel and non-obvious combinations and sub-combinations of various processes, systems and configurations, as well as other features, functions, behaviors and / or characteristics disclosed herein, and any and all equivalent schemes thereof.

Claims

1. A method for performing cyclic chemical vapor deposition (CVD) / etching processes to control the profile of a silicon-containing film deposited on a substrate, the substrate comprising spacer structures, each spacer structure comprising a top field region and one or more sidewalls, the method comprising: Perform multiple alternating CVD and etching steps. Each CVD step includes depositing a portion of the silicon-containing film on the spacer structure of the substrate, and Each etching step involves forming a plasma using a gas mixture containing a halogen-containing etchant to adjust the profile of the silicon-containing film.

2. The method of claim 1, wherein each CVD step is a plasma-enhanced CVD (PECVD) step, comprising forming a plasma using a gas mixture comprising one or more film precursors and an inert gas to deposit the portion of the silicon-containing film, and wherein the profile comprises vertical growth of the silicon-containing film on the top field region of each spacer structure.

3. The method of claim 2, wherein forming the plasma comprising one or more membrane precursors comprises: forming a continuous wave plasma.

4. The method according to claim 2, wherein the one or more membrane precursors comprise: a silicon-containing precursor, molecular nitrogen, and molecular hydrogen.

5. The method of claim 2, wherein each PECVD step is performed at a first pressure of 0.1 to 3 Torr and each etching step is performed at a second pressure greater than the first pressure.

6. The method of claim 5, wherein each etching step further comprises: reducing the pressure from the second pressure to the first pressure; and allowing the halogen-containing etchant to flow while reducing the pressure.

7. The method of claim 1, wherein the controlled contour comprises conformal growth on the top field area and the one or more sidewalls of each spacer structure.

8. The method of claim 7, wherein each CVD step is a PECVD step, comprising forming a plasma using a gas mixture comprising one or more film precursors and an inert gas to deposit said portion of the silicon-containing film.

9. The method according to claim 8, wherein, Forming the plasma containing one or more of the membrane precursors includes pulsed plasma.

10. The method of claim 8, wherein the one or more membrane precursors comprise a silicon-containing precursor and ammonia.

11. The method of claim 8, wherein each PECVD step is performed at a first pressure of 4 to 20 Torr and each etching step is performed at a second pressure equal to or less than the first pressure.

12. The method of claim 1, wherein the silicon-containing film comprises silicon nitride.

13. The method of claim 1, wherein the silicon-containing film comprises one of silicon oxide, silicon oxynitride, silicon carbide, silicon carbide, silicon oxynitride, or silicon oxynitride.

14. A plasma-enhanced chemical vapor deposition (PECVD) tool, comprising: Processing room; A substrate support is disposed in the processing chamber; A radio frequency power supply, configured to supply radio frequency power to form plasma in the processing chamber; Flow control hardware is configured to control the flow of gas from a membrane precursor source, an inert gas source, and an etchant chemical source into the processing chamber; as well as A controller configured to perform multiple alternating deposition and etching steps, the controller being configured to: During the deposition process, Operate the flow control hardware to cause the silicon-containing membrane precursor to flow from the membrane precursor source into the processing chamber and to cause the inert gas to flow from the inert gas source into the processing chamber; as well as The radio frequency power supply is operated under conditions configured to deposit a silicon-containing film on a spacer structure of a substrate supported by the substrate support to form a plasma comprising the silicon-containing film precursor and the inert gas, each spacer structure comprising a top field region and one or more sidewalls. as well as During the etching step, Operate the flow control hardware to cause the halogen-containing etchant chemicals to flow from the etchant chemical source into the processing chamber; as well as Under conditions configured to etch the silicon-containing film, the radio frequency power supply is operated to form a plasma containing the halogen-containing etchant chemicals.

15. The PECVD tool of claim 14, wherein the controller is configured to perform the etching step using one or more of a longer duration or a larger partial pressure of the halogen-containing etchant, compared to a previously performed etching step in the plurality of etching steps.

16. The PECVD tool of claim 14, wherein the controller is configured to operate the flow control hardware and discharge system of the PECVD tool during the deposition step to maintain the pressure between 0.1 and 3 Torr, and to operate the radio frequency power supply to form a continuous wave plasma to deposit the vertically grown silicon-containing film on the top field region of the spacer structure.

17. A method for performing plasma-enhanced chemical vapor deposition (PECVD) to control the vertical growth of a silicon-containing film deposited on a substrate, the substrate comprising spacer structures, each spacer structure comprising a top field region and one or more sidewalls, the method comprising: Multiple alternating deposition and etching steps are performed to deposit the silicon-containing film on the spacer structure of the substrate. Each deposition step involves forming a plasma using a gas mixture comprising a silicon-containing film precursor, a nitrogen-containing film precursor, hydrogen, and an inert gas to deposit the silicon-containing film on the spacer structure. Each etching step involves forming a plasma using a gas mixture containing a halogen-containing etchant to etch the silicon-containing film, thereby allowing the silicon-containing film to grow at a faster growth rate on the top field region of each spacer structure compared to the growth rate of the silicon-containing film on the one or more sidewalls of each spacer structure.

18. The method of claim 17, further comprising, while performing the plurality of alternating deposition and etching steps, reducing the duration of subsequent deposition steps and increasing the duration of subsequent etching steps.

19. The method of claim 17, wherein each deposition step is performed at a first pressure and each etching step is performed at a second pressure greater than the first pressure, and each etching step further comprises allowing the halogen-containing etchant to flow while reducing the pressure from the second pressure to the first pressure.

20. The method of claim 17, wherein forming the plasma in a subsequent deposition step of the plurality of deposition steps comprises: forming a plasma further comprising residual halogen-containing etchant from a previous etching step.

Images