Morphologically selective silicon oxide film formation method

Abstract

To provide a method of topology-selective film formation of silicon oxide.SOLUTION: A method for forming a silicon oxide film on a step formed on a substrate includes: (a) designing a topology of a final silicon oxide film by preselecting a target portion of an initial silicon nitride film to be selectively deposited or removed or reformed with reference to a non-target portion of the initial silicon nitride film resulting in the final silicon oxide film; and (b) forming the initial silicon nitride film and the final silicon oxide film on the surfaces of the step according to the topology designed in process (a). In process (b), the initial silicon nitride film is deposited by ALD using a silicon-containing precursor containing halogen, the initial silicon nitride film is converted to the final silicon oxide film by oxidizing the initial silicon nitride film without further depositing a film, and a Si-N bond in the initial silicon nitride film is converted to a Si-O bond.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates generally to a method for forming a silicon oxide film on a step having a top surface, sidewalls, and a bottom surface formed on a substrate, and more particularly to a method for morphologically selectively depositing silicon oxide films. [Background technology]

[0002] Related technologies Atomic layer deposition (ALD), including plasma-enhanced atomic layer deposition (PEALD), is widely used in semiconductor manufacturing processes to form conformal films on substrates with patterned surfaces. In some semiconductor manufacturing processes, the conformal film, once formed, undergoes a dry etching or other dry trimming process to anisotropically remove one or more portions of the film for specific applications. In such cases, the film formation process and the etching process are necessarily performed in two separate steps.

[0003] However, when etching thin films, the etching selectivity of the thin film, the underlying film, and the mask material, i.e., the difference in etching resistance between the thin film, the underlying film, and the mask material, is always a problem. For example, adverse effects on the underlying film (e.g., degradation of the quality of the underlying film due to penetrating ion energy and reduction of the critical dimension (CD) of the trench) are inevitable.

[0004] If the film formation itself can control the film morphology through anisotropic deposition and / or anisotropic modification processes, neither dry etching nor a separate dry trimming process is required, eliminating the adverse effects of dry etching on the underlying film, reducing the number of process steps, and improving throughput. However, because oxidation occurs rather isotropically during the film deposition process, it is very difficult to control the morphology of silicon oxide films.

[0005] A known technique for controlling the morphology of such films involves first depositing a SiN film on the patterned surface of a substrate under specific conditions that result in different wet etching rates for the horizontal and vertical portions of the pattern, followed by wet etching, thereby selectively leaving only the sidewall portions of the pattern or the horizontal portions of the pattern (e.g., as disclosed in U.S. Patent Publication No. 2017 / 0243734, the disclosure of which is incorporated by reference in its entirety as applicable to certain embodiments disclosed herein). This technique is sometimes referred to as morphology-selective film formation of SiN ("TS-SiN"). Because wet etching, rather than dry etching, is used to selectively remove only the vertical or horizontal portions of the pattern, it is possible to achieve the advantages of setting high wet etching selectivity of the pattern relative to the underlying film and not having to consider etching uniformity. While high wet etching selectivity can be achieved with TS-SiN by increasing RF power, these conditions do not work on SiO films to provide similar high wet etching selectivity. Therefore, there is a high demand in the semiconductor industry for morphology-selective film formation of SiO (“TS-SiO”), but TS-SiO has not been successfully realized.

[0006] Any discussion of problems and solutions related to the related art is included in this disclosure solely for the purpose of providing a background for the present invention, and should not be construed as an admission that any or all of the discussion was known at the time of the practice of the invention. Summary of the Invention [Means for solving the problem]

[0007] In some embodiments, a morphology-selective SiO (TS-SiO) film is formed on a substrate step by first depositing a SiN film selectively on the horizontal surfaces of the SiO film to be deposited on the substrate step, then anisotropically treating the horizontal surfaces (top and bottom surfaces of the step) by exposing the SiO film to a plasma containing NH or N / H with relatively high ion energy (this surface treatment is sometimes called "incubation" or "surface nitridation"), followed by PEALD of a SiN film selectively on the horizontal surfaces of the step using a halogen-containing precursor (this deposition process is sometimes called "nitridation"), where the precursor adsorbed on the substrate surface is nitrided and the halogen of the precursor is replaced with nitrogen in the nitridation gas by an exchange reaction (e.g., Si-Cl → Si-N), thereby forming a monolayer of SiN. In the second process, the deposited SiN film is converted into a SiO film by an oxidation process (this process is sometimes called "oxidization" or "oxidation"). The main component of the resulting film is SiO, and anisotropic nitridation can be repeated during the conversion of the film into a SiO film, so that the resulting film can grow only or mainly vertically, thereby achieving anisotropic PEALD.

[0008] Anisotropic or selective nitridation is achieved by anisotropic or selective incubation or surface nitridation, and the anisotropy is due to the anisotropic ion incidence of nitrogen-containing plasma. To treat the SiO surface, ion energy above a certain level is required. Therefore, anisotropic surface treatment can be achieved only or primarily on the portion of the SiO film exposed to ion energy, thereby introducing -NH termination on the surface. On the other hand, when oxidizing a SiN film, oxidation can easily occur with plasma without the assistance of ion energy. That is, oxidation can be achieved uniformly on the patterned structure.

[0009] When a patterned structure has a trench with a high aspect ratio and a narrow opening, the number of ions implanted into the trench is smaller than the number of ions irradiated onto the top surface. Therefore, nitridation does not occur inside the trench compared to the top surface. By utilizing the above phenomenon, when a pattern has a narrow opening, a SiO film can be selectively and mainly formed only on the top surface. The effective range of aspect ratios and opening sizes suitable for the above operation varies depending on the deposition conditions, such as deposition pressure and RF power.

[0010] Anisotropic or selective incubation, or surface nitridation, forms -NH terminations on the surface of the underlying SiO film onto which the SiN film is deposited. As a precursor for depositing the SiN film, precursors that can adsorb to the underlying SiO film with exposed Si-NH surfaces but hardly adsorb to the Si-O surface, such as SiCl4, Si2Cl6, etc., can be used.

[0011] If necessary, after converting the SiN film to SiO by oxidation, the patterned structure can be wet-etched using, for example, dHF, to remove any SiO film remaining on the sidewalls, thereby forming a complete TS-SiO film. In principle, the SiN film will deposit only on the top surface, but the surface selectivity of the precursor for depositing the SiN film, i.e., selective deposition on the Si-NH surface rather than the Si-O surface, may not be perfect. In this case, the SiN film may deposit slightly on the sidewalls, and isotropically oxidize to convert it to SiO. The remaining SiO film on the sidewalls can be removed by wet-etching the patterned structure. Note that the wet etch rate of the thermal oxide film, i.e., the wet etch rate of the top of the SiO film is 1, while the wet etch rate of the SiO film is approximately 2.2, regardless of position. Therefore, the wet etch rates of the sidewalls and the bottom of the SiO film are essentially or nearly equal. Therefore, although the wet etching etches not only the sidewall portion but also the top portion of the SiO film, the top portion of the SiO film is overwhelmingly or substantially thicker than the sidewall portion, so that a complete TS-SiO film can be obtained.

[0012] In some embodiments, the precursors used to deposit the SiN film are carbon-free, and the final silicon oxide film is carbon-free. This avoids the diffusion of carbon-containing impurities from the SiN film into the interface between the SiN film and the underlying film. After converting the SiN film to an SiO film, a carbon-free SiO film can be formed. By forming a carbon-free SiO film, degradation of the underlying film due to impurities, such as carbon migrating from the SiO film and entering the underlying film at the interface between the SiO film and the underlying film, can be avoided.

[0013] Some embodiments also feature the use of inorganic carbon-free, halogen-containing precursors and carbon-free reactants. Traditionally, when using halogen-containing precursors, deposition is aided by a nitrogen-containing hydrocarbon (linear or cyclic), e.g., pyridine, reactant, where the nitrogen displaces the halogen bonded to silicon in the precursor adsorbed on the substrate through an exchange reaction (e.g., Cl↔N) (e.g., Cl—Si), thereby forming a film composed of SiN material. However, because the reactant compound contains a hydrocarbon, the possibility of some carbon remaining in the film cannot be ignored. In addition, in some cases, the precursor contains a hydrocarbon. By using inorganic carbon-free, halogen-containing precursors and carbon-free reactants, carbon-free SiN films are deposited by PEALD, followed by a conversion process to convert the SiN film to a SiO film by oxidation.

[0014] When the above process is repeated to form an SiO film having a desired thickness, if the adsorption of the carbon-free precursor onto the SiO surface is insufficient, resulting in a decrease in growth per cycle (GPC) and / or a decrease in step coverage, the SiO surface may be exposed to a plasma of NH, N / H, etc. before the process of depositing the SiN film (i.e., before the precursor is supplied) to improve the adsorption of the precursor onto the substrate surface.

[0015] The morphology-selective processing techniques are not limited to the above embodiments and essentially combine the formation of nitride films by PEALD using silicon-containing precursors containing halogens and the oxidation of nitride films, and in some embodiments include the following three techniques:

[0016] 1) depositing a thin SiO film by ALD or CVD on a patterned substrate, and then depositing a SiN film by PEALD using a halogen-containing precursor by manipulating or adjusting RF power, wherein the SiN film grows selectively on horizontal surfaces, particularly the top surface, of the patterned substrate by an anisotropic incubation or surface nitridation process, the horizontal surfaces receiving more ion energy than the vertical surfaces, and the surface nitridation occurs substantially only or primarily on the horizontal surfaces rather than on the vertical surfaces;

[0017] 2) depositing a SiN film on a patterned substrate by ALD (thermal or plasma enhanced) using a halogen-containing precursor, and then converting the SiN film into a SiO film using an oxidizing material, such as O2, using plasma energy, UV light energy, thermal energy, or other energy, followed by wet etching, where the SiN film is deposited by applying RF power of 100-1,000 W for 5 seconds or less, resulting in incomplete nitridation of a portion of the film deposited on the sidewalls and insufficient resistance to the wet etching, thereby removing a portion of the film on the sidewalls by the wet etching and leaving a portion of the film deposited on horizontal surfaces;

[0018] 3) In the above 2), when depositing a SiN film, applying RF power of 100 W to 1,000 W for a period of more than 5 seconds can make the film properties, such as wet etching resistance, substantially equivalent among the portion of the film deposited on the top surface, the portion of the film deposited on the sidewall, and the portion of the film deposited on the bottom surface, thereby forming a conformal SiO film (carbon-free) after wet etching. In this disclosure, the RF power is shown for a 300 mm substrate, but if the RF power is used for a substrate with a different diameter, the applicable RF power can be calculated based on the watts per area of ​​the substrate (W / cm). 2 ) can be determined for the substrate by calculating

[0019] In some embodiments, the precursor is selected from carbon-free halogen-containing silane-based compounds, and the reactant (nitriding gas) is N2 / H2, NH3, or other N x H y (x and y are not zero).

[0020] In some embodiments, the carbon-free halogen-containing silane-based compounds include, but are not limited to, di-iodo-silane, dichlorosilane, hexachlorodisilane, and octachlorotrisilane, which may be used alone or in any combination of two or more of the foregoing.

[0021] In some embodiments, nitridation (substituting nitrogen for halogen by an exchange reaction) and oxidation are performed sequentially in the same reaction chamber, and after nitridation, the reaction chamber is purged with an inert gas, and an oxidizing gas, such as O, O, CO, N, O, HO, etc., or a combination of two or more thereof, is supplied to the chamber to effect oxidation, thereby forming a SiO film.

[0022] In some embodiments, the nitridation and oxidation cycles need not be repeated the same number of times, but by adjusting and varying the number of nitridation cycles and oxidation cycles, as well as by adjusting the RF power, the wet etch resistance of the film can be reduced (e.g., by increasing the number of oxidation cycles, decreasing the RF power for nitridation, and / or increasing the RF power for oxidation).

[0023] In some embodiments, by adjusting the wet etch resistance (wet etch rate) of films formed on the top surface, sidewalls, and bottom surface, portions of the top surface, sidewalls, and bottom surface can be selectively removed or preserved in a wet etch (e.g., using dHF).

[0024] In some embodiments, when nitridation and oxidation are performed by PEALD, the degree of adsorption of the precursor onto the substrate surface may decrease during oxidation. In this case, by improving the surface condition of the substrate during oxidation using a hydrogen-containing reducing gas, such as H2, NH3, etc., the adsorption characteristics of the halogen-containing precursor can be improved, thereby increasing the growth per cycle (GPC).

[0025] In this disclosure, SiN, SiO, SiOC, etc. are abbreviations that indicate non-stoichiometric film types unless otherwise specified.

[0026] Certain objects and advantages of the present invention are described in this disclosure for the purpose of summarizing aspects of the present invention and the advantages achieved over related technologies. Of course, it should be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, one skilled in the art will recognize that the present invention can be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages taught herein without necessarily achieving other objects or advantages taught or suggested herein.

[0027] Further aspects, features, and advantages of the present invention will become apparent from the following detailed description.

[0028] These and other features of the present invention will now be described with reference to the drawings of preferred embodiments which are intended to illustrate, rather than limit, the invention, and which have been greatly simplified for illustrative purposes and are not necessarily drawn to scale. [Brief explanation of the drawings]

[0029] [Figure 1A] FIG. 1A is a schematic diagram of a PEALD (Plasma Enhanced Atomic Layer Deposition) apparatus for depositing a protective film that can be used in one embodiment of the present invention. [Figure 1B]FIG. 1B is a schematic diagram of a precursor delivery system using a flow path system (FPS) that can be used in one embodiment of the present invention. [Figure 2] FIG. 2 is a flow chart illustrating a process for morphology-selective film formation, according to one embodiment of the present invention. [Figure 3] FIG. 3 is a flow chart illustrating a process for morphology-selective film formation according to another embodiment of the present invention. [Figure 4] FIG. 4 is a flow chart illustrating a process for morphology-selective film formation according to yet another embodiment of the present invention. [Figure 5] FIG. 5 is a flow chart illustrating a process for morphology-selective film formation according to yet another embodiment of the present invention. [Figure 6] FIG. 6 is a timing diagram illustrating a process sequence for morphology-selective film formation according to one embodiment of the present invention, where the width of each column does not necessarily represent an actual length of time, and where a rising level of each row line represents an ON state, while a lowest level of each row line represents an OFF state. [Figure 7] FIG. 7 illustrates a morphology-selective film formation process sequence according to another embodiment of the present invention, where gray cells represent the ON state while white cells represent the OFF state, and the width of each column does not represent the duration of each process. [Figure 8] FIG. 8 is a diagram showing a conventional process sequence for film formation, in which gray cells represent the ON state while white cells represent the OFF state, and the width of each column does not represent the duration of each process. [Figure 9] FIG. 9 is a schematic cross-sectional view illustrating a process for morphology-selective film formation according to one embodiment of the present invention. [Figure 10] FIG. 10 is a schematic cross-sectional view illustrating a process for morphology-selective film formation according to another embodiment of the present invention. [Figure 11] FIG. 11 is a schematic cross-sectional view illustrating a process for morphology-selective film formation according to yet another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0030] In this disclosure, "gas" can include vaporized solids and / or liquids and can be composed of a single gas or a mixture of gases. In this disclosure, the process gas introduced into the reaction chamber through the showerhead can be composed of, consist essentially of, or consist of precursor gases and additive gases. The precursor and additive gases can be introduced into the reaction space as a gas mixture or separately. The precursor gas can be introduced with a carrier gas, such as a noble gas. The additive gas can be composed of, consist essentially of, or consist of a reactant gas and a diluent gas, such as a noble gas. The reactant gas and diluent gas can be introduced into the reaction space as a gas mixture or separately. A precursor can be composed of two or more precursors, and a reactant gas can be composed of two or more reactant gases. A precursor is a gas that is chemisorbed on a substrate and typically contains a metalloid or metallic element that constitutes the main structure of the matrix of the dielectric film, and a reactant gas for deposition is a gas that can react with a precursor chemisorbed on the substrate when excited to fix an atomic layer or monolayer on the substrate. "Chemical absorption" refers to chemical saturation adsorption, which may also be simply referred to as "adsorption." Gases other than the process gas, i.e., gases introduced without passing through a showerhead, may be used, for example, to seal the reaction space with a sealing gas, such as a noble gas. In some embodiments, a "film" refers to a layer that extends continuously in a direction perpendicular to the thickness direction substantially without pinholes to cover the entire object or related surface, or simply a layer that covers the object or related surface. In some embodiments, a "layer" refers to a structure having a specific thickness formed on a surface, or a synonym for a film, or a non-film structure. A film or layer may be composed of a single individual film or layer or multiple films or layers with specific properties, and the boundaries between adjacent films or layers may or may not be distinct and may be defined based on any physical, chemical, and / or other characteristics, the formation process or sequence, and / or the function or purpose of the adjacent film or layer.

[0031] In this disclosure, "comprising an Si-O bond" refers to being characterized by an Si-O bond or bonds, having a main skeleton substantially composed of an Si-O bond or bonds, and / or having a substituent substantially composed of an Si-O bond or bonds. Dielectric films containing Si-O bonds include, but are not limited to, SiO, SiOC, and SiON films having a dielectric constant of about 2 to 10, typically about 4 to 8.

[0032] Additionally, in this disclosure, "a" or "an" refers to a species or genus, including multiple species, unless otherwise specified. The terms "composed of" and "having" independently refer, in some embodiments, to "typically or broadly including," "comprising," "consisting essentially of," or "consisting of." Also, in this disclosure, a defined meaning does not necessarily exclude, in some embodiments, the ordinary and customary meaning.

[0033] Moreover, in this disclosure, since feasible ranges can be determined based on routine practice, any two variables can constitute a feasible range for that variable, and any range stated can include or exclude endpoints. In some embodiments, further, any values ​​for stated variables (whether they are stated as "about" or not) refer to exact or approximate values, may include equivalents, and may refer to the mean, median, representative value, or majority, etc.

[0034] Where conditions and / or structures are not specified in this disclosure, those skilled in the art will be able to readily provide such conditions and / or structures in light of the present disclosure as a matter of routine experimentation. In all of the disclosed embodiments, any element used in the embodiments may be replaced with any element equivalent thereto, including those explicitly, necessarily, or inherently disclosed herein, for the intended purpose. Furthermore, the present invention is equally applicable to apparatus and methods.

[0035] The embodiments are described in terms of preferred embodiments, but the invention is not limited to the preferred embodiments.

[0036] An exemplary embodiment relates to a dielectric film formation process based on the PEALD technique, in which substantially only or primarily horizontal surfaces of a patterned template are surface-treated by anisotropic surface treatment using plasma, and a film is selectively grown on the surface-treated surface. Film growth occurs primarily in the vertical direction while suppressing horizontal film growth, thereby achieving a film profile with a desired morphology. This technique allows a film to be deposited substantially only on the top surface of the substrate, between the top surface and the sidewalls of recesses in the substrate. The term "substantially only" means, for example, 70%, 80%, 90%, or 95% or more of the total, e.g., a ratio of the average thickness of the portion of the film deposited on the top surface to the average thickness of the portion of the film deposited on the sidewalls of 7 / 3 or more.

[0037] For example, the bottom surface is also a horizontal surface, but the degree of film formation on the bottom surface depends on the aspect ratio. When the trench opening size is 50 nm or less, if the aspect ratio of the trench is high, e.g., 3 or greater, the amount of ions entering the trench is small compared to the amount on the top surface exposed to ion bombardment. As a result, the surface nitridation or incubation due to surface treatment (nitridation of the SiO surface) does not proceed as much on the bottom surface as on the top surface, so the thickness of the film grown on the bottom surface is smaller than that of the film grown on the top surface. By adjusting the aspect ratio of the recess, for example, by using a recess with an aspect ratio of 10 or greater, a film can be deposited substantially on the top surface of the top, sidewall, and bottom surfaces.

[0038] In some embodiments, the morphology-selective process includes: A) performing an anisotropic surface treatment (incubation or surface nitridation) using plasma in a manner that treats substantially only horizontal surfaces of a patterned substrate; B) depositing a nitride film on the surface-treated surface by PEALD (nitridation by exchange reaction between halogen and nitrogen) using a precursor containing a halogen-active group and a plasma such as NH, N / H, etc.; C) after purging the chamber, changing the gas in the reaction chamber to an oxidizing atmosphere by supplying, for example, O, and converting the nitride film to an oxide film by, for example, thermal oxidation, radical oxidation, plasma oxidation, etc.; and D) repeating steps A) to C) until the oxide film has a desired morphology-selective film profile and the oxide film thickness reaches a desired value.

[0039] In some embodiments, the oxide film is composed of SiO, SiOC, SiON, or the like. Due to an anisotropic surface treatment, the film grows substantially only vertically, not horizontally. By using high-aspect-ratio recesses, the film can be deposited substantially only on the top surface of the top, sidewall, and bottom surfaces. Furthermore, if necessary, the film on the sidewalls can be completely removed by isotropic wet etching (e.g., using dHF) of the final deposited oxide film, thereby forming a film profile in which only the film on the top and bottom surfaces remains. Furthermore, in some embodiments, the surface treatment and deposition processes can be performed sequentially using the same reaction chamber.

[0040] In a morphology-selective processing technique, the formation of a carbon-free SiO film grown on a substrate can be achieved by depositing a SiN film using a carbon-free precursor and a carbon-free nitriding reactant, such as N2, N2 / H2, or NH3, and then converting the SiN film to an SiO film by oxidizing the SiN film using an oxidizing gas, such as O2, HO, or by an oxidation exchange reaction. This technique can suppress the accumulation of impurities contained in the process gas (including precursors and reactants) at the interface between the SiO film and the underlying film during the SiO film formation process.

[0041] Some embodiments provide a method for forming a silicon oxide film on a step having a top surface, sidewalls, and a bottom surface formed on a substrate, the method comprising: (a) a process for designing a morphology of a final silicon oxide film, the final silicon oxide film being a conformal film or a film having low conformality, formed on the step by pre-selecting a target portion of an initial silicon nitride film, and selectively depositing, removing, or modifying the target portion relative to a non-target portion of the initial silicon nitride film to obtain the final silicon oxide film, the target portion being the top / bottom portion of the initial silicon nitride film formed on the top and bottom surfaces of the step, and (b) a process for forming an initial silicon nitride film and a final silicon oxide film on the surface of the step according to the morphology designed in process (a), wherein the initial silicon nitride film is deposited by atomic layer deposition (ALD) using a silicon-containing precursor that includes a halogen, and the initial silicon nitride film is converted to the final silicon oxide film by oxidizing the initial silicon nitride film without further film deposition, and the Si-N bonds of the initial silicon nitride film are converted to Si-O bonds. Figure 2 is a flowchart illustrating the above-described morphology-selective film formation process. As illustrated in Figure 2, there are three methods that can be used, alternatively or in any combination, to achieve the desired morphology of the final oxide film: selective deposition of a target portion of the film, selective removal of a target portion of the film, and selective modification of a target portion of the film.

[0042] In this disclosure, the term "step" or "depression" refers to any patterned structure formed in a substrate that consists of risers (sidewalls) and treads (top surfaces) relative to a reference surface (bottom surface), and in some embodiments, the step may be a trench having a width of about 10 to about 50 nm (typically about 15 to about 30 nm) (when a trench has a length approximately the same as its width, it is called a hole / via, and its diameter is about 10 to about 50 nm), a depth of about 30 to about 200 nm (typically about 50 to about 150 nm), and an aspect ratio of about 3 to about 20 (typically about 3 to about 10). In some embodiments, the final silicon oxide film is formed selectively on top surfaces (having a conformality of about 0 to about 10%, about 20%, or about 30% or less) or uniformly along steps or trenches in the substrate (having a conformality of about 70% to about 110%, typically about 80% or more, more typically about 90% or more, and 100% or less), where "conformality" is determined by comparing the film thickness formed at a point on the sidewall or bottom of a recess (usually the midpoint in a cross-sectional view) with the film thickness formed on the flat surface (top surface) just outside the recess.

[0043] In some embodiments, the precursors used in process (b) are carbon-free and the final silicon oxide film is carbon-free.

[0044] In some embodiments, the formation of the initial silicon nitride film (sometimes referred to as "nitridation," in which reactant nitrogen replaces the absorbed precursor halogen through an exchange reaction) and the oxidation of the initial silicon nitride film are performed sequentially in the same reaction space in process (b). In some embodiments, the reaction space is purged after the formation of the initial silicon nitride film and before the oxidation of the initial silicon nitride film. The oxidation of the initial silicon nitride film is performed by plasma oxidation in the reaction space to which an oxidizing gas, which is at least one gas selected from the group consisting of O, O, CO, N, O, and H, is introduced. In this disclosure, "sequentially," in some embodiments, refers to the absence of a vacuum break, a time-series interruption, a change in processing conditions immediately following a subsequent step, or a discrete physical or chemical boundary between the two structures. The nitridation typically must be substantially complete because any remaining halogen in the nitride film may be considered an impurity, like carbon, which may migrate into the interface between the nitride film and the underlying film.

[0045] In some embodiments, the initial silicon nitride film is composed of multiple monolayers, and in process (b), oxidation of the initial silicon nitride film occurs after each monolayer deposition cycle of ALD of the initial silicon nitride film, or after every multiple monolayer deposition cycle of ALD of the initial silicon nitride film.

[0046] In some embodiments, the target portion preselected in process (a) is a target portion to be selectively deposited, and process (b) includes (ci) depositing a silicon oxide film on a surface of a step on a substrate; and (cii) anisotropically nitriding the surface of the silicon oxide film using a nitrogen-hydrogen containing plasma generated by applying RF power between two electrodes arranged parallel to the substrate to the two electrodes in a manner that nitrides the surface of the silicon oxide film primarily on the top and bottom surfaces of the step, rather than on the sidewalls of the step, thereby (ciii) depositing at least a portion of an initial silicon nitride film by ALD on and in contact with the surface-treated silicon oxide film using a precursor and a nitriding gas excited by a plasma generated by applying RF power between two electrodes; (civ) oxidizing at least a portion of the initial silicon nitride film using the excited oxidizing gas, whereby at least a portion of a final silicon oxide film is obtained without further film deposition, and the Si-N bonds of the initial silicon nitride film are converted to Si-O bonds; and (cv) repeating processes (cii) and (civ) as necessary until a final silicon oxide film having a desired thickness is obtained. Figure 3 is a flow chart illustrating the above process for morphology-selective film formation.

[0047] In some embodiments, the nitrogen-hydrogen containing plasma in process (cii) is a mixture of N2 and H2, NH3, other N x H y where x and y are integers or mixtures of two or more thereof.

[0048] In some embodiments, the silicon oxide film of process (ci) is deposited by ALD or CVD.

[0049] In some embodiments, the preselected target portion in process (a) is a target portion to be selectively removed, and process (b) includes (di) depositing at least a portion of an initial silicon nitride film on a surface of a step on the substrate by ALD using precursor and reactant gases excited by a plasma generated by applying RF power between two electrodes with the substrate positioned parallel to the two electrodes, wherein the RF power is 0.14 W / cm per area of ​​the substrate for each monolayer deposition cycle of the ALD. 2 ~1.41W / cm 2(dii) oxidizing at least a portion of the initial silicon nitride film using an excited oxidizing gas to obtain at least a portion of an intermediate silicon oxide film without depositing any further films, and the Si-N bonds of the initial silicon nitride film are converted to Si-O bonds; (diii) repeating processes (di) and (dii) as necessary until an intermediate silicon oxide film having a desired thickness is obtained; and (div) wet-etching the intermediate silicon oxide film to obtain a final dielectric film, thereby removing primarily the target portion relative to the non-target portion. Figure 4 is a flowchart illustrating the above-described morphology-selective film formation process.

[0050] In some embodiments, the oxidation in process (dii) is carried out using plasma, UV light, heat, or a combination of two or more of these.

[0051] In some embodiments, the RF power used in the process (di) is 0.14 W / cm per area of ​​the substrate. 2 ~0.71W / cm 2 and the oxidation in process (dii) is plasma oxidation performed after each monolayer deposition cycle of the first silicon nitride film or after every multiple monolayer deposition cycle of the first silicon nitride film in process (di), and the plasma is generated between two electrodes with the substrate positioned parallel to the two electrodes at a power of 0.07 W / cm per area of ​​the substrate. 2 ~0.71W / cm 2 is generated by applying RF power of

[0052] In some embodiments, process (diii) is performed immediately before each repetition of process (di) by exposing the stepped surface of the substrate to a hydrogen-containing reducing gas to treat the surface with a hydrogen-containing reducing gas.

[0053] In some embodiments, the hydrogen-containing reducing gas is at least one gas selected from the group consisting of H2 and NH3.

[0054] In some embodiments, in the process (div), the wet etching is a wet etching using dHF.

[0055] In some embodiments, the target portion preselected in process (a) is a selectively modified target portion, and process (b) comprises (ei) depositing at least a portion of an initial silicon nitride film on a surface of a step on the substrate by ALD using precursor and reactant gases excited by a plasma generated by applying RF power between two electrodes arranged parallel to the substrate, the RF power being 0.14 W / cm per area of ​​the substrate for each monolayer deposition cycle of the ALD. 2 ~1.41W / cm 2 (e) applying a voltage of 0.1 V to the target portion for a period of time greater than 5 seconds, thereby rendering the chemical resistance of the target portion substantially equal to that of the non-target portion when subjected to wet etching; (eii) oxidizing at least a portion of the initial silicon nitride film using an excited oxidizing gas, to obtain at least a portion of an intermediate silicon oxide film without depositing any further film, and converting Si-N bonds of the initial silicon nitride film to Si-O bonds; (eiii) repeating processes (e) and (eii) as necessary until an intermediate silicon oxide film of a desired thickness is obtained; and (eiv) wet etching the intermediate silicon oxide film to obtain a final dielectric film, thereby forming a final silicon oxide film having high conformality. Figure 5 is a flow chart illustrating the above-described morphology-selective film formation process.

[0056] In some embodiments, the oxidation in process (eii) is carried out using plasma, UV light, heat, or a combination of two or more of these.

[0057] In some embodiments, the RF power used in the process (ei) is 0.71 W / cm per area of ​​the substrate. 2 ~1.41W / cm 2 and the oxidation in process (eii) is plasma oxidation performed after each monolayer deposition cycle of the first silicon nitride film or after every multiple monolayer deposition cycle of the first silicon nitride film in process (ei), and the plasma is 0.07 W / cm per area of ​​the substrate between two electrodes with the substrate positioned parallel to the two electrodes. 2 ~0.71W / cm 2 is generated by applying RF power of

[0058] In some embodiments, process (eiii) is performed immediately prior to each repetition of process (ei) by exposing the stepped surface of the substrate to a hydrogen-containing reducing gas to treat the surface with a hydrogen-containing reducing gas.

[0059] In some embodiments, the hydrogen-containing reducing gas is at least one gas selected from the group consisting of H2 and NH3.

[0060] In some embodiments, in process (eiv), the wet etch is a wet etch using dHF.

[0061] In some embodiments, the etch is a wet etch using dHF, the concentration of which is about 0.1%.

[0062] The present invention will now be described in detail with reference to preferred embodiments illustrated in the drawings, but it is not intended that the invention be limited to these embodiments.

[0063] 6 is a timing diagram illustrating a process sequence for morphology-selective film formation according to one embodiment of the present invention, where the width of each column does not necessarily represent an actual time length, and the rising level of each row line represents an ON state, while the lowest level of each row line represents an OFF state. By this method, a TS-SiO film with a thick top can be formed by selective deposition of the target portion (top).

[0064] In FIG. 6, selective deposition of the target portion (top) of the film includes three processes: an incubation process, a nitridation (deposition) process, and an oxidation process. Prior to the incubation process, a silicon oxide film is deposited as an underlayer film on the surface of the step on the patterned substrate. The incubation process involves anisotropically nitriding the surface of the silicon oxide film using a nitrogen-hydrogen-containing plasma generated using a nitriding gas (reactant 1) by applying RF power between two electrodes arranged parallel to the substrate (treatment 3), thereby nitriding the surface of the silicon oxide film primarily on the top and bottom surfaces of the step rather than on the sidewalls of the step, thereby introducing -NH termination onto the surface of the silicon oxide film. In the incubation process, in some embodiments, the flow rate of reactant 1 ranges from 500 sccm to 10,000 sccm (preferably from 1,000 sccm to 5,000 sccm), and treatment 3 ranges from 1 second to 20 seconds (preferably from 3 seconds to 10 seconds).

[0065] Next, the nitridation (deposition) process begins, which involves depositing at least a portion of an initial silicon nitride film on the surface-treated silicon oxide film by PEALD using a precursor (precursor) and a nitriding gas (reactant 1) excited by a plasma generated by applying RF power between two electrodes (process 1). Process 3 of the incubation process and process 1 of the nitridation process both involve applying RF power. However, the conditions for applying RF power can be the same for both processes 3 and 1. However, in some embodiments, process 3 preferably uses stronger ion energy to achieve anisotropic surface nitridation than process 1. Therefore, in some embodiments, process 3 uses higher RF power and / or lower pressure than process 1. For example, process 3 uses 0.07 W / cm. 2 ~1.4W / cm 2 (preferably 0.14W / cm 2 ~0.7W / cm 2 ) is applied under a pressure of 100 Pa to 3000 Pa (preferably 200 Pa to 1000 Pa), but in treatment 1, the RF power is 0.07 W / cm 2 ~1.4W / cm 2 (preferably 0.14W / cm 2 ~0.7W / cm 2 ) is applied under a pressure of 100 Pa to 2000 Pa (preferably 200 Pa to 1000 Pa). The nitridation (deposition) process is a PEALD process, and one cycle to form a monolayer may be repeated N times until the desired thickness of the nitride film is obtained, where N is an integer between 10 and 1000 (preferably 10 to 30) to deposit a nitride film with a thickness of 5 nm to 100 nm (preferably 10 nm to 30 nm), depending on the application of the film. In one PEALD cycle, the duration of the precursor pulse, the duration of reactant 1, and the duration of treatment 1 are in the range of 0.1 seconds to 20 seconds.

[0066] Thereafter, an oxidation process begins, which involves oxidizing at least a portion of the initial silicon nitride film (Treatment 2) using an oxidizing gas (Reactant 2) excited by RF power, to obtain at least a portion of the final silicon oxide film without further film deposition, and converting the Si-N bonds of the initial silicon nitride film into Si-O bonds. For example, in Treatment 2, 0.07 W / cm 2 ~1.4W / cm 2 (preferably 0.07W / cm 2 ~0.7W / cm 2 ) is applied under a pressure of 100 Pa to 3000 Pa (preferably 200 Pa to 1000 Pa). In the oxidation process, in some embodiments, the flow rate of reactant 2 is in the range of 10 sccm to 1000 sccm (preferably 50 sccm to 500 sccm), and the duration of treatment 2 is in the range of 0.1 seconds to 20 seconds (preferably 0.5 seconds to 10 seconds).

[0067] Throughout the process, the inert gas (inert gas) is continuously supplied to the reaction chamber at a rate of 500 sccm to 10,000 sccm (preferably 1,000 sccm to 5,000 sccm). The process temperature can be in the range of 0°C to 600°C (preferably 200°C to 500°C).

[0068] Furthermore, if necessary, the incubation process, nitridation process, and oxidation process can be repeated M times until a final silicon oxide film having a desired thickness is obtained, depending on the application of the film, etc., where M is an integer of 1 to 30 (preferably 1 to 15).

[0069] FIG. 9 illustrates a schematic cross-sectional view showing a process for morphology-selective film formation according to the embodiment illustrated by the timing diagram in FIG. 6 . State (a) is a state prior to state (b), in which a SiO film 43 is formed on the surface of a substrate 41 having a step 42 (trench). State (b) represents a state during an incubation process, in which the surface of the SiO film 43 is nitrided by an anisotropic nitrogen-containing plasma, and an —NH termination is introduced on the SiO surface, thereby forming a SiNH surface 44 on the SiO film 43. State (c) represents a state during a nitridation process, in which a SiN film 46 is deposited and grown on the SiNH surface 44 by PEALD. When the SiN film 46 undergoes an oxidation process, the SiN film 46 is converted into a SiN film similar to the SiN film 43 in state (a). These steps are then repeated to obtain the desired final SiO film (a thick TS-SiO film) on the substrate.

[0070] In some embodiments, the selective deposition scheme can be carried out under the conditions shown in Table 1 below.

[0071] [Table 1]

[0072] 7 illustrates a morphology-selective film formation process sequence according to another embodiment of the present invention, where gray cells represent the ON state while white cells represent the OFF state, and the width of each column does not represent the duration of each process. This method can form a thick-top TS-SiO film by selectively removing the target portion of the film (sidewalls), and can also form a conformal TS-SiO film by selectively modifying the target portion of the film (top surface versus sidewalls).

[0073] The process sequence includes a nitridation / deposition process ("Delivery" → "Purge" → "RF Pulse-1 (Nitridation / Reduction)" → "Purge"), an oxidation process ("Add Reactant-2" → "RF Pulse-2 (Oxidation)" → "Purge"), and a wet etching process ("DHF Dip"). The nitridation process involves depositing at least a portion of an initial silicon nitride film on a step surface on a substrate by PEALD using a precursor (Si precursor) and a reactant gas (reactant-1) excited by a plasma generated by applying RF power (RF) between two electrodes arranged parallel to the substrate, where the RF power is 0.14 W / cm per area of ​​the substrate for each monolayer deposition cycle of PEALD. 2 ~1.41W / cm 2 (preferably 0.07W / cm 2 ~0.71W / cm 2 ) is applied for 5 seconds or less (preferably 1 to 3 seconds), so that when wet-etched, the chemical resistance (wet-etching resistance) of the target portion (sidewall) is lower than that of the non-target portion. By using the above RF power application conditions, the portion of the film deposited on the sidewall is insufficiently nitrided to maintain wet-etching resistance compared to the portion of the film deposited on the top / bottom surface, thereby allowing the sidewall portion to be selectively removed by wet-etching.

[0074] The nitridation (deposition) process is a PEALD process, and one cycle for forming a monolayer may be repeated q times until the desired thickness of the nitride film is obtained, where q is an integer between 10 and 1000 (preferably between 30 and 500) to deposit a nitride film with a thickness of 5 nm to 100 nm (preferably between 10 nm and 30 nm), depending on the application of the film. In one PEALD cycle, the duration of the "Si-precursor" pulse, the duration of the "reactant-1" pulse, and the duration of the "RF" pulse range from 0.1 seconds to 20 seconds (preferably between 0.1 seconds and 10 seconds). In some embodiments, the RF power is applied under a pressure of 100 Pa to 2000 Pa (preferably between 200 Pa and 1000 Pa). In some embodiments, the flow rate of reactant-1 in the nitridation process ranges from 500 sccm to 10,000 sccm (preferably between 2,000 sccm and 5,000 sccm). In this embodiment, the "reactant-1" and "carrier gas / diluent gas" flow continuously.

[0075] Next, an oxidation process begins, which involves oxidizing at least a portion of the initial silicon nitride film using an oxidizing gas (reactant-2) excited by RF power (RF) to obtain at least a portion of an intermediate silicon oxide film without further film deposition, and converting the Si-N bonds of the initial silicon nitride film to Si-O bonds, e.g., 0.07 W / cm 2 ~1.4W / cm 2 (preferably 0.07W / cm 2 ~0.7W / cm 2 ) is applied under a pressure of 100 Pa to 2000 Pa (preferably 200 Pa to 1000 Pa). In the oxidation process, in some embodiments, the flow rate of "reactant-2" is in the range of 10 sccm to 1000 sccm (preferably 50 sccm to 500 sccm), and the duration of "RF" is in the range of 0.1 seconds to 10 seconds (preferably 0.1 seconds to 5 seconds).

[0076] Throughout the process, the carrier gas and / or diluent gas can be continuously supplied to the reaction chamber at a rate ranging from 500 sccm to 10,000 sccm (preferably from 1,000 sccm to 5,000 sccm), and the process temperature can be in the range of 0°C to 600°C (preferably from 200°C to 500°C).

[0077] Furthermore, if necessary, the nitridation / deposition process and oxidation process are repeated p times depending on the application of the film, etc., until an intermediate silicon oxide film having a desired thickness is obtained, where p is an integer of 1 to 30 (preferably 1 to 15).

[0078] Then, the wet etching process (DHF dip) begins, which involves wet etching the intermediate silicon oxide film to obtain the final dielectric film, thereby primarily removing the target portions (sidewalls) relative to the non-target portions. In some embodiments, the wet etching can be performed by etching the substrate using hydrofluoric acid or a known or new suitable equivalent / substitute diluted to 0.1% to 1.5% at a temperature of 15° C. to 25° C. for 30 seconds to 600 seconds.

[0079] FIG. 10 illustrates a schematic cross-sectional view showing a morphology-selective film formation process according to the embodiment represented by the process sequence illustrated in FIG. 7 . State (a) represents a state during a nitridation / deposition process, in which a SiN film 53 is formed on the surface of a substrate 51 having a step 52 (trench). State (b) represents a state during an oxidation process, in which the SiN film 53 is subjected to the oxidation process and converted into an SiO film 54. The nitridation / deposition and oxidation processes are then repeated as necessary until the desired thickness of the SiO film is obtained. State (c) represents a state by wet etching, in which the portion of the film deposited on the sidewall has lower wet-etching resistance than the portion on the top / bottom surface. The sidewall portion of the film can be selectively removed significantly or completely, while the other portion maintains a considerable thickness. Thus, the desired final SiO film (a thick TS-SiO film) can be formed on the substrate.

[0080] The RF power applied between the two electrodes was 0.14 W / cm per area of ​​the substrate. 2 ~1.41W / cm 2 (preferably 0.07W / cm 2 ~0.71W / cm 2 ) is applied for longer than 5 seconds for each ALD monolayer deposition, the resulting SiO film's film properties, e.g., resistance to wet etching, can be substantially equal among the portion of the film deposited on the top surface, the portion of the film deposited on the sidewalls, and the portion of the film deposited on the bottom surface, thereby forming a conformal SiO film (carbon-free) after wet etching.

[0081] FIG. 11 illustrates a schematic cross-sectional view showing the process of morphology-selective film formation represented by the process sequence illustrated in FIG. 7, modified as described above. State (a) represents the state during the nitridation / deposition process, in which a SiN film 63 is formed on the surface of a substrate 61 having a step 62 (trench). State (b) represents the state during the oxidation process, in which the SiN film 63 is oxidized and converted into an SiO film 64. The nitridation / deposition and oxidation processes are then repeated as needed until the desired thickness of the SiO film is obtained. State (c) represents the state during wet etching, in which the portion of the film deposited on the top surface, the portion of the film deposited on the sidewall, and the portion of the film deposited on the bottom surface have substantially similar resistance to wet etching, so all portions are etched approximately evenly as needed. Thus, the desired final SiO film (a conformal, carbon-free, homogeneous TS-SiO film) can be formed on the substrate.

[0082] In some embodiments, the nitriding in selective removal of the target portion (FIG. 10) and selective modification of the target portion (FIG. 11) can be performed under the conditions shown in Table 2 below.

[0083] [Table 2]

[0084] In some embodiments, the selective modification scheme uses a higher flow rate of the nitrogen-containing gas and a longer RF power application time than the selective removal scheme to improve film conformality. In other words, in some embodiments, the selective removal scheme uses a lower flow rate of the nitrogen-containing gas and a shorter RF power application time than the selective modification scheme to increase film growth on flat (horizontal) surfaces relative to vertical surfaces.

[0085] 8 illustrates a conventional process sequence for film formation, where gray cells represent the ON state while white cells represent the OFF state, and the width of each column does not represent the duration of each process. Conventional processes do not perform processes that correspond or are equivalent to those described above in connection with embodiments of the present invention, and therefore do not logically form conformal, carbon-free, uniform SiO films.

[0086] In the process sequence described in this disclosure, precursors may be supplied in pulses using a continuously supplied carrier gas. This can be achieved using a flow-path system (FPS), which provides a bypass line with a precursor reservoir (bottle) in the carrier gas line and switches between the main line and the bypass line. When only carrier gas is intended to be supplied to the reaction chamber, the bypass line is closed. When both carrier gas and precursor gas are intended to be supplied to the reaction chamber, the main line is closed, and the carrier gas flows through the bypass line and exits the bottle along with the precursor gas. In this way, carrier gas can continuously flow into the reaction chamber, and precursor gas can be pulsed by switching between the main line and the bypass line. Figure 1B illustrates a precursor supply system using a flow-path system (FPS) according to an embodiment of the present invention (black valves indicate closed valves). As shown in Figure 1B(a), when a precursor is supplied to a reaction chamber (not shown), a carrier gas, such as Ar (or He), first flows through a gas line with valves b and c and enters the bottle (reservoir) 30. The carrier gas flows out of the bottle 30, carrying the precursor gas in an amount corresponding to the vapor pressure within the bottle 30, flows through a gas line having valves f and e, and is supplied to the reaction chamber together with the precursor. In the above state, valves a and d are closed. When only the carrier gas (noble gas) is supplied to the reaction chamber, the carrier gas flows through the gas line having valve a, bypassing the bottle 30, as shown in (b) of FIG. 1B. In the above state, valves b, c, d, e, and f are closed.

[0087] The precursor may be delivered using a carrier gas. Because ALD is a self-limiting adsorption reaction process, the number of deposited precursor molecules is determined by the number of reactive surface sites and is independent of precursor exposure after saturation; the precursor delivery is such that the reactive surface sites are saturated with each cycle. The plasma for deposition may be generated in situ, for example, in ammonia gas that flows continuously throughout the deposition cycle. In other embodiments, the plasma may be generated remotely and delivered to the reaction chamber.

[0088] As noted above, each pulse or step of each deposition cycle is preferably self-limiting. Excess reactants are provided at each step to saturate the susceptible structure surface. Surface saturation ensures reactant occupation of all available reactive sites (subject to limitations, e.g., physical size or "steric hindrance") and therefore excellent step coverage. In some embodiments, the pulse time of one or more of the reactants can be reduced so that full saturation is not achieved and less than a monolayer is adsorbed onto the substrate surface.

[0089] For example, any suitable apparatus, including the apparatus illustrated in FIG. 1A, can be used to perform the process cycle. FIG. 1A is a schematic diagram of a PEALD apparatus, preferably integrated with a controller programmed to execute the sequence described below, that can be used in some embodiments of the present invention. In this diagram, a pair of conductive flat electrodes 4, 2 are arranged parallel and facing each other in the interior 11 (reaction region) of a reaction chamber 3. HRF power (13.56 MHz or 27 MHz) 20 is applied to one side, and the other side 12 is electrically grounded, thereby exciting a plasma between the electrodes. A temperature controller is provided on the lower stage 2 (lower electrode), maintaining the temperature of the substrate 1 placed thereon at a predetermined constant temperature. The upper electrode 4 also functions as a shower plate, and reactant gases (and noble gases) and precursor gases are introduced into the reaction chamber 3 through gas lines 21 and 22, respectively, and through the shower plate 4. Furthermore, a circular duct 13 with an exhaust line 7 is provided within the reaction chamber 3, through which gases within the interior 11 of the reaction chamber 3 are exhausted. Furthermore, a dilution gas is introduced into the reaction chamber 3 through a gas pipe 23. Furthermore, the transfer chamber 5, located below the reaction chamber 3, is provided with a seal gas pipe 24 for introducing a seal gas into the interior 11 of the reaction chamber 3 through the interior 16 (transfer zone) of the transfer chamber 5. A separation plate 14 is provided to separate the reaction zone from the transfer zone (the gate valve through which the wafer is transferred into and out of the transfer chamber 5 is omitted from this figure). The transfer chamber is also provided with an exhaust pipe 6. In some embodiments, the deposition and surface treatment of the multi-element film are performed in the same reaction space, so all steps can be performed consecutively without exposing the substrate to air or other oxygen-containing atmospheres. In some embodiments, a remote plasma device can be used to excite the gases.

[0090] In some embodiments, the system illustrated in FIG. 1A for switching between inert gas flow and precursor gas flow, as illustrated in FIG. 1B (discussed above), can be used to introduce precursor gases in pulses without substantially fluctuating the pressure in the reaction chamber.

[0091] In some embodiments, a dual chamber reactor (two zones or compartments for processing wafers positioned adjacent to each other) can be used, and the reactant gas and noble gas can be supplied through shared lines, while the precursor gas is supplied through non-shared lines.

[0092] Those skilled in the art will appreciate that the apparatus includes one or more controllers (not shown) programmed or configured to operate the deposition and reactor cleaning processes described elsewhere herein, and as will be appreciated by those skilled in the art, the controllers are in communication with the various power supplies, heating systems, pumps, robots, and gas flow controllers or valves of the reactor.

[0093] The present invention will be further described with reference to the following examples, but the present invention is not limited to these examples. In cases where conditions and / or structures are not specified, those skilled in the art can easily provide such conditions and / or structures in light of the present disclosure through routine experimentation. Furthermore, the numbers applied to specific examples can be modified in some embodiments by at least ±50%, and the numerical values ​​are approximate.

[0094] Example

[0095] Example 1

[0096] In this example, selective modification of the target portion of the film illustrated in FIG. 5 was performed. First, a 20-nm-thick SiN film was formed by PEALD on a Si substrate (300 mm diameter) with a trench (30-nm opening, aspect ratio 3). The SiN film was then converted to a SiO film using the PEALD apparatus illustrated in FIG. 1A and the gas supply system (FPS) illustrated in FIG. 1B under the general conditions shown in Table 3 below and the specific conditions shown in Table 4, according to the process sequence illustrated in FIG. 7 . The substrate was then wet-etched under the conditions shown in Table 3 below. As a comparative example, a SiO film was deposited in a similar manner to the above, according to the process sequence illustrated in FIG. 8 , without the nitridation / deposition process or the oxidation (conversion) process.

[0097] [Table 3]

[0098] [Table 4]

[0099] Each SiO film was evaluated and the results are shown in Table 5 below.

[0100] [Table 5]

[0101] In Table 5, "Saturation" in "GPC Trend by Purge Time" indicates that the purge process was performed in such a way that the reaction process of each PEALD cycle occurred at the saturation of the adsorbed precursor according to GPC (growth per cycle). "Lateral Coverage" refers to conformality (%). "PLE" refers to the ratio of the narrow dimension to the wide dimension. "100:1 DHF-WERR (TOX ratio)" refers to the wet etch rate relative to the wet etch rate of a thermal oxide film using hydrofluoric acid diluted to 1%. "<5" in "Carbon" refers to carbon detected at less than 5 at%. "ND" means "not detected."

[0102] As shown in Table 5, according to the examples, the SiO films obtained in all examples were high-quality conformal carbon-free SiO films, while in the comparative examples the SiO films were low-quality SiOC films.

[0103] It will be apparent to those skilled in the art that many variations and modifications can be made without departing from the spirit of the present invention. Therefore, it is apparent that the forms of the present invention are illustrative only and do not limit the scope of the present invention. [Explanation of symbols]

[0104] 2, 4 Conductive plate electrode 3. Reaction Chamber 5 Transfer chamber 7 Exhaust line 11 Inside the reaction chamber 13 Circular Duct 14 Separation plate 16 Inside the transfer chamber 20 HRF Power 21, 22 Gas lines 24 Seal gas pipe a~f valves 30 bottles 41 Base material 42 steps 43 SiO film 44 SiNH surface 46 SiN film 51 Base material 52 steps 53 SiN film 54 SiO film 61 Base material 62 steps 63 SiN film 64 SiO film

Claims

1. A method for forming a silicon oxide film on a step having a top surface, a sidewall, and a bottom surface formed on a substrate, comprising: (ci) depositing a silicon oxide film on the surface of the step on the substrate; (cii) anisotropically nitriding the surface of the silicon oxide film using a nitrogen-hydrogen containing plasma generated by applying RF power between two electrodes with the substrate disposed parallel to the two electrodes in a manner that nitrides the surface of the silicon oxide film primarily on the top and bottom surfaces of the step, rather than on the sidewalls of the step, thereby introducing -NH terminations onto the surface of the silicon oxide film; (ciii) depositing at least a portion of an initial silicon nitride film on and in contact with the surface-treated silicon oxide film by atomic layer deposition (ALD) using a silicon-containing precursor and a nitriding gas, the silicon-containing precursor including a halogen, excited by a plasma generated by applying RF power between the two electrodes; (civ) oxidizing said at least a portion of said initial silicon nitride film using an excited oxidizing gas to obtain at least a portion of a final silicon oxide film having conformal or low conformality without further film deposition, wherein Si—N bonds of said initial silicon nitride film are converted to Si—O bonds; (cv) repeating processes (cii) and (civ) as necessary until the final silicon oxide film having a desired thickness is obtained.

2. 10. The method of claim 1, wherein the precursor is carbon-free and the final silicon oxide film is carbon-free.

3. 10. The method of claim 1, wherein the forming of the initial silicon nitride film and the oxidation of the initial silicon nitride film occur sequentially in the same reaction space.

4. The reaction space is purged after forming the first silicon nitride film and before oxidizing the first silicon nitride film, and the oxidation of the first silicon nitride film comprises O ２ , O ３ , CO ２ , N ２ O, and H ２ 4. The method of claim 3, wherein the plasma oxidation is carried out in the reaction space into which an oxidizing gas, which is at least one gas selected from the group consisting of O, is introduced.

5. 2. The method of claim 1, wherein the initial silicon nitride film is composed of multiple monolayers, and the oxidation of the initial silicon nitride film occurs after each monolayer deposition cycle of the initial silicon nitride film or after every multiple monolayer deposition cycle of the initial silicon nitride film.

6. The nitrogen-hydrogen containing plasma in process (cii) is ２ and H ２ , N.H. ３ , and other N ｘ H ｙ 10. The method of claim 1, wherein x and y are integers or a mixture of two or more thereof.

7. 10. The method of claim 1, wherein the silicon oxide film of process (ci) is deposited by ALD or CVD.

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