Method and system for forming silicon nitride on a sidewall of a feature

Abstract

A method for forming silicon nitride on the sidewall of a feature is disclosed. An exemplary method comprises the steps of providing a substrate comprising a feature including a sidewall surface and a surface adjacent to the sidewall surface, forming a silicon oxide layer on the sidewall surface and the surface adjacent to the sidewall surface, depositing a silicon nitride layer on the silicon oxide layer using a periodic deposition process, and exposing the silicon nitride layer to an active species generated from a hydrogen-containing gas. An exemplary method may further comprise the step of selectively removing a portion of the silicon nitride layer. A structure formed using the present method and a system for performing the present method are also disclosed.

Description

Technology Field

[0001] The present disclosure generally relates to a method and system for forming a device. More specifically, an example of the present disclosure relates to a method and system for forming silicon nitride on the surface of a substrate. Background Technology

[0002] Silicon nitride layers can be used in various applications during the formation of electronic devices. For example, silicon nitride layers can be used as dielectric layers, diffusion barriers, hard masks, spacers, etc.

[0003] In some applications, it may be desirable to primarily form silicon nitride on the sidewall surfaces of the feature, so that no or relatively little silicon nitride remains on the surfaces adjacent to the sidewalls (e.g., top and bottom surfaces). One technique for forming silicon nitride on the sidewall surfaces includes the steps of depositing a thin conformal layer of silicon nitride, processing a portion of the silicon nitride layer, and selectively removing the processed silicon nitride using a wet etching process. This technique may result in bubble formation and / or delamination of the silicon nitride layer, particularly on the surfaces adjacent to the sidewall surfaces, after processing and before selectively removing a portion of the silicon nitride layer. Bubble formation and / or delamination may cause unwanted removal and / or changes in removal of the silicon nitride material from or near the bottom of the vertical sidewall surface. Unwanted removal of the silicon nitride material may eventually lead to unwanted changes in the silicon nitride material remaining on the vertical surfaces and / or device performance. Bubble formation and delamination can become increasingly problematic as the thickness of the silicon nitride layer decreases (e.g., to less than 20 nm or less than 10 nm).

[0004] Other techniques for forming silicon nitride on sidewall surfaces include using high-frequency (RF) power during the deposition of a silicon nitride layer on a feature and using a wet etching process to remove silicon nitride on a surface adjacent to the sidewall surface. However, these techniques often result in an undesirable large amount of silicon nitride layer being removed near the intersection of the sidewall and adjacent surface(s).

[0005] Therefore, an improved method for forming silicon nitride on the sidewall surface of a feature is required. Additionally, a structure suitable for forming a device is also required, including a system for forming silicon nitride and a structure.

[0006] Any discussion of the problems and solutions stated in this section is included in this disclosure merely for the purpose of providing context for the present disclosure, and should not be construed as an acknowledgment that all or part of such discussion was known at the time the invention was made.

[0007] Various embodiments of the present disclosure relate to a method for forming silicon nitride on a sidewall of a feature, a system for forming silicon nitride on a sidewall of a feature, and a structure comprising silicon nitride on a sidewall. Silicon nitride can be used in the formation of devices, such as semiconductor devices.

[0008] The ways in which various embodiments of the present disclosure address the problems of prior methods, systems, and structures are discussed in more detail below, but generally, various embodiments of the present disclosure provide an improved method for forming silicon nitride on a vertical surface. The method may cause less bubble formation and / or delamination of the silicon nitride on or near the bottom surface of a feature. Thus, the silicon nitride film formed on the sidewall surface may contain the desired material remaining at the bottom edge of the feature. Furthermore, the technique described herein may cause less variation in the silicon nitride formed on the sidewall surface, which may result in better and more predictable device performance.

[0009] According to an exemplary embodiment of the present disclosure, a method for forming silicon nitride on a sidewall of a feature is provided. One or more exemplary methods include providing a substrate having a feature including a sidewall surface and a surface adjacent to the sidewall surface (e.g., bottom) in a reaction chamber; forming a silicon oxide layer on the sidewall surface and the adjacent surface; depositing a silicon nitride layer on the silicon oxide layer using a periodic deposition process; and exposing the silicon nitride layer to an active species generated from a hydrogen-containing gas. The exemplary methods may also include the step of selectively removing a portion of the silicon nitride layer on the surface adjacent to the sidewall surface for a portion of the silicon nitride layer placed on the sidewall surface. According to various embodiments of the present disclosure, the periodic deposition process includes the steps of providing a silicon precursor and providing a nitrogen reactant. According to further embodiments of the present disclosure, the periodic deposition process includes a plasma-enhanced periodic deposition process. The step of selectively removing may include a wet etching process or a dry etching process. The wet etching process may include the use of an HF-based aqueous solution, such as an HF aqueous solution or an aqueous solution containing HF and NH4F. The dry etching process may include the use of an active species formed from a plasma generated from a fluorine-containing gas such as NF3, SF6, CF4, etc. The step of forming a silicon oxide layer may include one or more ALD, CVD, PVD, thermal oxidation, rapid thermal oxidation, coating, plasma oxidation, radical oxidation, etc.

[0010] According to a further embodiment of the present disclosure, a structure is provided. The structure may be formed according to a method as described herein. The structure may comprise a substrate having one or more features, each comprising a vertical surface or a sidewall and a silicon nitride disposed on the sidewall.

[0011] According to additional examples of the present disclosure, an element is formed using or includes a structure described herein.

[0012] According to another additional exemplary embodiment of the present disclosure, a system configured to perform the method described herein and / or to form a structure is provided.

[0013] The present invention is not limited to any specific embodiment(s) disclosed, and these and other embodiments will be readily apparent to those skilled in the art from the following detailed description of specific embodiments with reference to the accompanying drawings. Brief explanation of the drawing

[0014] A more complete understanding of the exemplary embodiments of the present disclosure can be derived by referring to the detailed description of the invention and the claims, when considered in conjunction with the following exemplary drawings. Figure 1 shows a silicon nitride film formed on a substrate, and the silicon nitride layer is peeled off from the surface of the substrate. FIG. 2 illustrates a method according to at least one embodiment of the present disclosure. FIG. 3 shows the chronological order of a method according to an example of the present disclosure. FIGS. 4 to 8 show a structure according to an embodiment of the present disclosure. FIGS. 9 and FIGS. 10 show additional structures according to examples of the present disclosure. FIG. 11 shows a system according to at least one embodiment of the present disclosure. It will be understood that the elements of the drawings are depicted in a simplified and clear manner and are not necessarily drawn to scale. For example, to aid in understanding the embodiments illustrated in this disclosure, the dimensions of some components in the drawings may be exaggerated compared to other components. Specific details for implementing the invention

[0015] Although specific embodiments and examples are disclosed below, those skilled in the art will understand that the present invention extends beyond the specifically disclosed embodiments and / or uses of the present invention and obvious variations and equivalents thereof. Accordingly, the scope of the disclosed invention is not intended to be limited by the specific disclosed embodiments described below.

[0016] The present disclosure generally relates to a method for forming silicon nitride on the sidewall of a feature, a structure comprising a silicon nitride layer, and a system for performing said method or forming the structure. As described in more detail below, various methods may be used to form a structure comprising silicon nitride on the sidewall surface of a feature, and the desired silicon nitride remains at the bottom of the sidewall / feature. Additionally or alternatively, the silicon nitride on the sidewall surface may be formed in a more predictable manner and / or the device performance may be improved.

[0017] In the present disclosure, the gas may include materials that are gas, vaporized solid, and / or vaporized liquid at normal temperature and pressure, and may consist of a single gas or a mixture of gases depending on the context. For example, the precursor or reactant gas may include the precursor or reactant and an inert gas. Gases other than the process gas, i.e., gases introduced without passing through a gas distribution assembly such as a showerhead or other gas distribution device, may include a sealing gas such as a rare gas or other inert gas, for example, which may be used to seal the reaction space. The term inert gas refers to a gas that does not participate in the chemical reaction to a significant degree and / or is capable of exciting the precursor when plasma power is applied. The terms precursor and reactant may be used interchangeably.

[0018] As used herein, the term substrate may refer to any underlying material or materials that can be used to form, or upon which an element, circuit, or film can be formed. The substrate may include a bulk material such as silicon (e.g., single-crystal silicon), other Group IV materials such as germanium, or compound semiconductor materials such as GaAs, and may include one or more layers placed on or beneath the bulk material. Additionally, the substrate may include various features formed within or on at least a portion of the layers of the substrate, such as indentations, lines, protrusions, etc. As a specific example, the substrate may include a bulk semiconductor material having features formed on or within it.

[0019] In some embodiments, a film refers to a layer extending perpendicular to the thickness direction to cover the entire target or surface of interest, or simply a layer covering the target or surface of interest. In some embodiments, a layer refers to a structure having a specific thickness formed on a surface, or refers to a synonym for a film or a non-film structure. A layer may be continuous or discontinuous. A film or layer may consist of a single film or layer or multiple films or layers having specific characteristics, and the boundary between adjacent films or layers may be clear or not, and may be constructed or not constructed based on physical, chemical, and / or any properties, formation processes and sequences, and / or the function or purpose of adjacent films or layers. In some cases, a portion of a layer or film may be removed (e.g., by etching), and the remainder of the film or layer may be referred to as a layer or film.

[0020] In the present disclosure, one or more of the following may be referred to: continuously, without vacuum breakdown, without temporal interruption, without a step of intervention of any material, without a change in processing conditions immediately thereafter as a next step, or in some embodiments, without a separate physical or chemical structure other than the two structures intervening between the two structures.

[0021] The term periodic deposition process or cyclic deposition process may refer to the deposition of a layer on a substrate by sequentially introducing precursors (and / or reactants) into a reaction chamber, and includes processing techniques such as atomic layer deposition (ALD) and periodic chemical vapor deposition (periodic CVD), and hybrid periodic deposition processes including ALD components and periodic CVD components.

[0022] As used herein, the term atomic layer deposition (ALD) may refer to a vapor deposition process, wherein deposition cycles, preferably a plurality of consecutive deposition cycles, are performed in a process chamber. Generally, during each cycle, a precursor is introduced and may be chemisorbed onto a deposition surface (e.g., a substrate surface, or a previously deposited underside such as material from a previous ALD cycle) to form a monolayer or sub-monolayer that does not readily react with additional precursors (i.e., self-limiting reaction). Subsequently, a reactant (e.g., another precursor or reaction gas) is subsequently introduced into the process chamber to convert the chemisorbed precursor on the deposition surface into the desired material. Generally, such reactants may further react with the precursor. During each cycle, purge steps may be further utilized to remove excess precursor from the process chamber and / or to remove excess reactant and / or reaction byproducts from the process chamber after the conversion of the chemisorbed precursor. Additionally, as used herein, the term atomic layer deposition also includes processes specified by related terms such as chemical vapor atomic layer deposition, atomic layer epitaxy (ALE), molecular beam epitaxy (MBE), gas source MBE, or organometallic MBE, and chemical beam epitaxy, when performed with alternating pulses of precursor composition(s), reaction gas, and purge (e.g., inert carrier) gas. PEALD refers to an ALD process, wherein plasma is applied during one or more of the ALD steps.

[0023] As used herein, silicon oxide refers to a material containing silicon and oxygen. Silicon oxide has the compositional formula SiO₂ x It can be expressed as, where x can be 1 to 2 (e.g., SiO2). In some cases, silicon oxide may not contain stoichiometric silicon oxide. In some cases, silicon oxide may contain other elements such as carbon, nitrogen, hydrogen, etc.

[0024] As used herein, silicon nitride refers to a material containing silicon and nitrogen. In some cases, silicon nitride may not contain stoichiometric silicon nitride. In some cases, silicon nitride may contain other elements such as carbon, oxygen, hydrogen, etc.

[0025] Additionally, in this disclosure, any two values ​​of a variable may constitute an executable range of said variable, and any indicated range may include or exclude endpoints. Additionally, any value of the indicated variable may refer to an exact value or an approximate value (regardless of whether an approx. is indicated) and may include an equivalent, and in some embodiments may refer to an average, median, representative, majority, etc. Also, in this disclosure, the terms include, include, constitute by, and have may independently refer to, in some embodiments, or ordinarily or approximately include, include, essentially constitute, or constitute. In this disclosure, any defined meaning in some embodiments is not necessarily excluded from the ordinary and conventional meaning.

[0026] Now, returning to the drawings, FIG. 1 shows a structure (100) comprising feature portions (102, 104) and a silicon nitride layer (112) formed on the feature portions (102, 104). The feature portion (102) includes a vertical surface or side wall (106), and the feature portion (104) includes a vertical surface or side wall (108). A bottom horizontal plane (110) extends between the feature portions (102 and 104). As shown, the silicon nitride layer (112) is peeled off on the bottom surface (110). Such peeling may occur, for example, during processing of the silicon nitride layer (112). During subsequent etching of the silicon nitride layer placed on the bottom surface (110), a change in unwanted material removal may occur in the regions (114 and 116). Examples of the present disclosure mitigate or eliminate such peeling and bubble formation.

[0027] FIG. 2 illustrates a method (200) according to an example of the present disclosure. FIGS. 4 through 8 illustrate a structure formed following various steps of the method (200).

[0028] The method (200) comprises the steps of providing a substrate within a reaction chamber (202), forming a silicon oxide layer (204), depositing a silicon nitride layer using a periodic deposition process (206), exposing the silicon nitride layer to an active species (208), and selectively removing a portion of the silicon nitride layer on a surface adjacent to a sidewall surface (210). Unless otherwise noted, the method according to the present disclosure does not need to include all steps of the method (200) shown in FIG. 2.

[0029] During step (202), a substrate (e.g., substrate (402) shown in FIG. 4) or a structure (400) is provided. The substrate may comprise any of the materials described above. According to an embodiment of the present disclosure, the substrate comprises a feature (e.g., feature (404, 406)) including a sidewall surface (e.g., sidewall surface (408, 410, 414, 416)) and a surface adjacent to the sidewall surface (e.g., bottom surface (412)). As an example, the substrate may comprise a bulk semiconductor (e.g., silicon) material.

[0030] During step (204), a silicon oxide layer (e.g., the silicon oxide layer (502) shown in FIG. 5) is formed on the surface of the substrate to form a structure (500). For example, the silicon oxide layer may be formed on the sidewall surface and the bottom surface of the substrate. The silicon oxide layer may be formed using any suitable method such as one or more ALD, CVD, PVD, thermal oxidation, rapid thermal oxidation, coating, plasma oxidation, radical oxidation, etc. The thickness of the silicon oxide layer may be greater than 1.5 nm, greater than 2 nm, or greater than 2.8 nm, and / or less than 50 nm, less than 10 nm, or less than 5 nm. In some cases, the thickness of the silicon oxide exceeds 1.1 nm or 1.5 nm to effectively prevent or mitigate delamination.

[0031] During step (206), a silicon nitride layer (e.g., silicon nitride layer (602)) is formed on a silicon oxide layer (e.g., silicon oxide layer (502)) to form a structure (600). Step (206) may begin loading the substrate onto a susceptor in the reaction chamber. Once the substrate is loaded onto the susceptor, the gate valve may be closed. In some cases, the susceptor may be moved to an operating position. During step (206), the temperature inside the reaction chamber and / or the substrate may be about 200°C to about 600°C, about 300°C to about 550°C, or about 350°C to about 500°C. Similarly, the pressure inside the reaction chamber may be controlled to provide a reduced pressure inside the reaction chamber for a subsequent process. For example, the pressure inside the reaction chamber may be about 200 to 6000 Pa, or about 350 to about 4000 Pa, or about 400 to about 3000 Pa.

[0032] Using a periodic deposition process, the silicon nitride layer deposition step (206) may include the step of providing a silicon precursor and the step of providing a nitrogen reactant to a reaction chamber.

[0033] An exemplary silicon precursor for use with step (206) comprises one or more of alkylaminosilanes, aminosilanes, and halosilanes. As an example, silicon precursors are bisdiethylaminosilane (BDEAS), bisdimethylaminosilane (BDMAS), hexylethylaminosilane (HEAD), tetraethylaminosilane (TEAS), tert-butylaminosilane (TBAS), bisdimethylaminodimethylaminosilane (BTBAS), bisdimethylaminodimethylaminosilane (BDMADMS), heptamethyldisilazane (HMDS), trimethicyldithelamin (TMSDEA), trimethylsiledimetramin (TMSDMA), trimethyltrivinylcyclotrisilazane (TMTVCTS), tritrimethylhydroxyamine (TTMSHA), bisdimethylsaminomethylsilane (BDMAMS), dimethylsilyldimethylamine (DMSDMA), silane, SiXH3 or SiX2H2 or SiX3H or SiX4 (where X is one of Cl, Br, or I), XH2Si-SiXH2 or X2HSi-SiX2H or It may include one or more precursors selected from the group consisting of X3Si-SiX3 (where X is one of Cl, Br, and I).

[0034] An exemplary nitrogen reactant for use in step (206) comprises one or more reactants selected from the group consisting of, for example, nitrogen and ammonia. The reactant may be provided to a reaction chamber together with an inert gas. For example, the reactant may flow jointly into the reaction chamber with an inert gas such as one or more of argon and helium.

[0035] The step (206) of depositing a silicon nitride layer may be a plasma-enhanced cyclic deposition process or may include such a process. The plasma-enhanced cyclic deposition process may be a direct plasma process or may include such a process. During the step (206), the plasma power may be about 300 W to about 2000 W, about 500 W to about 1500 W, or about 700 W to about 1000 W.

[0036] The thickness of the silicon nitride can be, for example, about 2 nm to about 30 nm, about 3 nm to about 20 nm, or about 4 nm to about 10 nm.

[0037] Once the silicon nitride layer has been formed to a desired thickness, during step (208), the silicon nitride layer (e.g., layer (602)) may be exposed to an active species generated from a hydrogen-containing gas to form a structure (e.g., the structure (700) shown in FIG. 7). The hydrogen-containing gas may include, for example, hydrogen, and an inert gas including one or more of nitrogen, argon, and helium. The volume ratio of hydrogen to inert gas may be, for example, in the range of about 1 to about 20 or about 10 to about 0.

[0038] Activating species can be generated, for example, from a direct plasma within a reaction chamber. During step (208), plasma conditions can be selected so that the activating species are directional and preferentially interact with the silicon nitride layer (602) on the horizontal surface to form a transformation region (702-710). The transformation region (702-710) may be relatively easy to etch compared to the silicon nitride material in the region (712-718), i.e., on the sidewalls (408, 410, 414, and 416). As an example, the plasma frequency during step (208) may be about 10 MHz to about 2.5 GHz. During step (208), the plasma power may be about 500 W to about 2000 W, about 600 W to about 1500 W, or about 700 W to about 1000 W.

[0039] During step (210), the structure (e.g., structure (700)) is exposed to an etching process to selectively remove the conversion region (702-710), while other parts of the silicon nitride layer (e.g., parts (802-808)) remain on the structure (e.g., structure (800)) as shown in FIG. 8. As used herein, selective etching may mean that the etching rate of the silicon nitride conversion region (702-710) is higher (e.g., 2, 5, or 10 times or more) than the etching rate of the silicon nitride material in the region (712-718).

[0040] The etching process may include a wet etching process and / or a dry etching process. The wet etching process may include, for example, using dilute hydrofluoric acid alone or in combination with NH4F. The dry etching may include a plasma generated from a gas containing one or more fluorine-containing gases, such as NF3, SF6, and CF4.

[0041] FIG. 3 illustrates a time sequence (300) suitable for various methods and / or steps of the method, including, for example, steps (206 and 208) of the method (200). The time sequence (300) includes one or more periodic deposition cycles (302) and one or more hydrogen treatment steps (304). To obtain a desired film thickness prior to the hydrogen treatment step (304), one or more periodic deposition cycles may be repeated multiple times (e.g., about 50 to about 5000 times). As further indicated, the time sequence according to the example of the present disclosure may include a rest period A, a stabilization period B, and / or a hydrogen flow period C.

[0042] In the illustrated example, the time sequence (300) includes a silicon precursor pulse period (306), a reactant pulse period (308), and a deposition plasma pulse period (310), a hydrogen-containing gas period (312), and a processing plasma pulse period (314). As used herein, a pulse period refers to the period during which a gas (e.g., precursor, reactant, inert gas, and / or carrier gas) flows into a reaction chamber and / or the period during which power is applied (e.g., power to generate plasma). The height and / or width of the illustrated pulse periods do not necessarily indicate a specific amount or duration of the pulse.

[0043] Table 1 below shows exemplary ranges for flow rate, plasma power, and other parameters for pulse periods (306-312, B and C), which may be the same or similar to the various conditions described above in conjunction with steps (206, 208) of the method (200).

[0044]

[0045] FIG. 9 shows a transmission electron microscope image of a structure (900) including a silicon oxide layer (906) and a silicon nitride layer (904) treated on a substrate (902). In contrast to the example shown in FIG. 1, as shown, the silicon nitride layer (904) does not show any bubble formation or peeling from the substrate (902).

[0046] FIG. 10 shows a transmission electron microscope image of a structure (1000) after selective etching (e.g., step (210)). As shown, the structure (1000) includes feature portions (1002 and 1004) each comprising silicon nitride (1006, 1008, 1010 and 1012) formed thereon. As previously described, silicon nitride was formed on a silicon oxide layer. As shown, the silicon nitride remains in the region (1014-1020) to provide desired structure characteristics and device performance.

[0047] Now, returning to FIG. 11, a reactor system (1100) according to an exemplary embodiment of the present disclosure is shown. The reactor system (1100) may be used to perform and / or perform one or more steps or substeps described herein, or to form one or more structures or parts thereof described herein.

[0048] The reactor system (1100) comprises a pair of electrically conductive flat plate electrodes (4, 2) that are parallel to each other and face each other within the interior (11) (reaction zone) of the reaction chamber (3). Although illustrated as a single reaction chamber, the system (1100) may comprise two or more reaction chambers. For example, by applying HRF power (e.g., 100 kHz, 13.56 MHz, 27 MHz, 2.45 GHz, or any value between these) from a plasma power source (30) to one electrode (e.g., electrode (4)) and electrically grounding the other electrode (e.g., electrode (2)), plasma can be excited within the reaction chamber (3). A temperature controller may be provided on the lower stage (2) (lower electrode), and the temperature of the substrate (1) placed thereon may be maintained at a desired temperature, e.g., the aforementioned substrate temperature. The electrode (4) may function as a gas distribution device, such as a shower plate or a shower head. If there is a precursor gas, a reactant gas, a carrier, or an inert gas, etc., one or more of the gas lines (23), gas lines (24), gas lines (25), or gas lines (27) can be introduced into the reaction chamber (3) from each source (21, 22, 20, and 26) and through the shower plate (4) using the gas line (23), gas line (24), gas line (25), or gas line (27). Although shown as four gas lines (23, 24, 25, and 27), the reactor system (1200) may include any suitable number of gas lines. As an example, source (21) may correspond to a precursor source (containing one or more silicon precursors), source (22) may correspond to a nitrogen reactant source, source (20) may correspond to a hydrogen reactant source, and source (26) may correspond to an inert gas source.

[0049] A circular duct (13) having an exhaust line (7) may be provided in the reaction chamber (3), through which gas inside (11) of the reaction chamber (3) can be exhausted. Additionally, a transfer chamber (5) positioned below the reaction chamber (3) may be provided with a sealing gas line (29) for introducing sealing gas into the inside (11) of the reaction chamber (3) through the inside (transfer zone) (16) of the transfer chamber (5), and a separator plate (14) for separating the reaction zone and the transfer zone may be provided (a gate valve through which the substrate is transferred to or from the transfer chamber (5) is omitted from the drawing). The transfer chamber may also be provided with an exhaust line (6) coupled to an exhaust source (32). In some embodiments, a continuous flow of carrier gas into the reaction chamber (3) may be performed using a flow pass system (FPS).

[0050] The reactor system (1100) may include one or more controller(s) (28) otherwise configured or programmed to perform one or more method steps described herein. The controller(s) (28) are combined with various power sources, heating systems, pumps, robotics, and gas flow controllers or valves of the reactor, as understood by those skilled in the art. As an example, the controller (28) may be configured to control the gas flow of a precursor, a reactant, and an inert gas into at least one of one or more reaction chambers to form a silicon nitride layer on a substrate surface (including a silicon oxide layer). The controller may be further configured to provide an activated species generated from a hydrogen-containing gas to the silicon nitride layer.

[0051] In some embodiments, a dual-chamber reactor (two sections or compartments for processing substrates placed close together) may be used, and the reactant gas and return gas may be supplied through a shared line, while the precursor gas is supplied through a non-shared line.

[0052] The exemplary embodiments of the present disclosure described above do not limit the scope of the invention, for these embodiments are merely examples of embodiments of the invention. Any equivalent embodiments are intended to be within the scope of the invention. Certainly, in addition to the embodiments shown and described herein, various modifications of the present disclosure, such as alternative useful combinations of the described elements, may be apparent to those skilled in the art from the description. Such modifications and embodiments are also intended to be within the scope of the appended claims.

Claims

Claim 1 A method for forming silicon nitride on a sidewall of a feature, the method comprising: providing a substrate comprising a feature including a sidewall surface and a surface adjacent to the sidewall surface; forming a silicon oxide layer on the sidewall surface and the surface adjacent to the sidewall surface; depositing a silicon nitride layer on the silicon oxide layer using a periodic deposition process; generating an active species from a hydrogen-containing gas; exposing the silicon nitride layer to the active species generated from the hydrogen-containing gas; and selectively removing the silicon nitride layer and the silicon oxide layer from the horizontal surface using a selective etching process, wherein the active species preferentially interact with the silicon nitride layer on the horizontal surface compared to the sidewall surface. Claim 2 A method according to claim 1, wherein the silicon oxide layer comprises nitrogen. Claim 3 A method according to claim 1, wherein the periodic deposition process comprises the step of providing a silicon precursor; and the step of providing a nitrogen reactant. Claim 4 In paragraph 3, the method wherein the silicon precursor comprises one or more of alkylaminosilane, aminosilane, and halosilane. Claim 5 In claim 3, the silicon precursor is bis-diethylaminosilane (BDEAS), bis-dimethylaminosilane (BDMAS), hexylethylaminosilane (HEAD), tetraethylaminosilane (TEAS), tert-butylaminosilane (TBAS), bis-tert-butylaminosilane (BTBAS), bis-dimethylaminodimethylaminosilane (BDMADMS), heptamethyldisilazane (HMDS), trimethicyldithelamin (TMSDEA), trimethylsiledimetramin (TMSDMA), trimethyltrivinylcyclotrisilazane (TMTVCTS), tritrimethylhydroxyamine (TTMSHA), bis-dimethylaminomethylsilane (BDMAMS), dimethylsilyldimethylamine (DMSDMA), silane, SiXH3 or SiX2H2 or SiX3H or SiX4 (where X is one of Cl, Br, or I). , A method comprising one or more precursors selected from the group consisting of XH2Si-SiXH2 or X2HSi-SiX2H or X3Si-SiX3 (where X is one of Cl, Br, and I). Claim 6 In paragraph 3, the method comprises the nitrogen reactant including one or more of nitrogen and ammonia. Claim 7 In paragraph 3, the method comprises a reactant gas including the nitrogen reactant and an inert gas including one or more of argon and helium. Claim 8 A method according to claim 1, wherein the periodic deposition process comprises a plasma-enhanced periodic deposition process. Claim 9 A method according to claim 8, wherein the power provided to generate plasma during the step of generating an active species from a hydrogen-containing gas is 300 W to 2000 W. Claim 10 A method according to claim 1, wherein the hydrogen-containing gas comprises hydrogen and an inert gas comprising one or more of nitrogen, argon, and helium. Claim 11 A method according to claim 1, wherein the step of optionally removing includes the step of using a wet etching process. Claim 12 A method according to claim 1, wherein the step of selectively removing includes the step of using a dry etching process. Claim 13 The method according to claim 1, wherein the thickness of the silicon oxide layer is greater than 1.5 nm and less than 5 nm. Claim 14 A method according to claim 1, wherein the substrate comprises silicon. Claim 15 A method according to claim 1, wherein the step of generating an active species from a hydrogen-containing gas includes the step of using direct plasma. Claim 16 In claim 15, the power provided to generate the direct plasma is 500 W to 2000 W. Claim 17 A method according to claim 1, wherein the temperature during the step of depositing a silicon nitride layer is 300°C to 550°C. Claim 18 A method according to claim 1, wherein the pressure during the step of depositing a silicon nitride layer is 200 Pa to 6000 Pa. Claim 19 A method according to claim 1, wherein the pressure during the step of exposing the silicon nitride layer to an active species is 100 Pa to 500 Pa. Claim 20 A method according to any one of claims 1 to 19, further comprising a stabilization period prior to the step of exposing a silicon nitride layer to an active species generated from a hydrogen-containing gas. Claim 21 delete Claim 22 delete Claim 23 delete

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