Method for forming topologically selective membranes of silicon oxide

Abstract

A method for forming a silicon oxide film on a staircase formed on a substrate, comprising: (a) designing a topography of a final silicon oxide film by selectively depositing or removing or reforming a target portion of an initial silicon nitride film to produce the final silicon oxide film, with reference to a non-target portion of the initial silicon nitride film; and (b) forming the initial silicon nitride film and the final silicon oxide film on a surface of the staircase according to the topography designed in process (a), wherein the initial silicon nitride film is deposited by ALD using a silicon-containing precursor containing halogen, and the initial silicon nitride film is converted into the final silicon oxide film by oxidizing the initial silicon nitride film without further depositing a film, wherein Si-N bonds in the initial silicon nitride film are converted into Si-O bonds.

Description

TECHNICAL FIELD

[0001] The present invention relates generally to a method of forming a topologically selective silicon oxide film on a staircase formed on a substrate having a top surface, sidewalls, and a bottom surface. BACKGROUND

[0002] Atomic layer deposition (ALD) methods, including plasma enhanced atomic layer deposition (PEALD) methods, are widely used in semiconductor manufacturing processes as a method of forming conformal films on substrates having patterned surfaces. In some semiconductor manufacturing processes, a film that has been formed as a conformal film once is subjected to a dry etching or other dry trimming process in order to anisotropically remove one or more portions of the film for a particular application. In this case, the film forming process and the etching process must be performed in two steps.

[0003] However, it has always been a problem that there is a certain degree of difference in etching selectivity of the thin film, the underlying film, and the mask material, i.e., etch resistance between the thin film, the underlying film, and the mask material, and, for example, adverse effects on the underlying film (e.g., a decrease in quality of the underlying film by a penetration ion energy, a decrease in a critical dimension (CD) of a trench) are unavoidable when etching the thin film.

[0004] If the film formation itself can control the topography of the film by an anisotropic deposition and / or an anisotropic reformation process, then a dry etching or other dry trimming process is not required, thereby eliminating adverse effects of dry etching on the underlying film, reducing the number of process steps, and improving yield. However, it is very difficult to control the topography of a silicon oxide film because oxidation occurs quite anisotropically in a film deposition process.

[0005] As a technique for such a control film topology, it is well known that, first, a SiN film is deposited on a patterned surface of a substrate under certain conditions so that the wet etching rate of the horizontal portion and the vertical portion of the pattern is different, and then wet etching is performed, thereby selectively leaving only the sidewall portion of the pattern or the horizontal portion of the pattern (as disclosed in, for example, U.S. Patent Publication No. 2017 / 0243734, the disclosure of which is incorporated herein by reference in its entirety to the extent applicable to certain embodiments disclosed herein). This technique can be referred to as topography-selective film formation of SiN (“TS-SiN”). In the above, since wet etching is used instead of dry etching to selectively remove only the vertical or horizontal portion of the pattern, a high wet etching selectivity of the pattern with respect to the underlying film can be set, and the advantage that uniformity of etching does not need to be considered can be achieved. In TS-SiN, a high wet etching selectivity can be obtained by increasing the RF power; however, such a condition is not suitable for imparting a similar high wet etching selectivity on a SiO film. Thus, although there is a high demand for topography-selective film formation of SiO (“TS-SiO”) in the semiconductor industry, TS-SiO has not been successfully implemented.

[0006] Any discussion of problems and solutions in relation to the related art has been included in this disclosure solely for the purpose of providing a context for the present application, and should not be taken as an acknowledgement or any admission that any or all of the discussion was known before the filing date of the application. SUMMARY

[0007] In some embodiments, a topography-selective SiO (TS-SiO) film is formed in the steps of a substrate by first selectively depositing a SiN film on the horizontal surfaces of a SiO film deposited in the steps of the substrate, wherein the horizontal surfaces (top and bottom surfaces of the steps) are mainly selectively treated by anisotropic plasma by exposing the SiO film to an NH3 or N2 / H2 containing plasma with relatively high ion energy (this surface treatment can be referred to as “incubation” or “surface nitridation”), followed by PEALD of the SiN film mainly selectively on the horizontal surfaces of the steps using a halogen containing precursor (this deposition process can be referred to as “nitridation”), in which the precursor adsorbed on the substrate surface is nitridated, in which the halogen in 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. As a second process, the deposited SiN film is converted to a SiO film by an oxidation treatment (this treatment can be referred to as “oxidization / oxidation”), thereby making the resulting film mainly SiO, and since the anisotropic nitridation treatment can be repeated when the film is converted to a SiO film, the resulting film can grow only or mainly in the vertical direction, thereby enabling anisotropic PEALD.

[0008] Anisotropic nitridation or selective nitridation is achieved by anisotropic or selective incubation or surface nitridation, the anisotropy of which is due to the incidence of anisotropic ions of the nitrogen-containing plasma. In order to treat the SiO surface, a certain level of ion energy is required, and thus the anisotropic surface treatment can be achieved substantially only or mainly in a portion of the SiO film exposed to the ion energy, thereby introducing -NH end groups at the surface. On the other hand, when oxidizing the SiN film, oxidation can be easily performed by plasma without ion energy assistance, i.e., the oxidation treatment can be completed uniformly on the patterned structure.

[0009] When the patterned structure has a trench with a high aspect ratio and a narrow opening, the number of ions injected into the inside of the trench is less than the number of ions radiated to the top surface. Thus, nitridation does not occur in the inside of the trench as compared with the top surface. By taking advantage of the above phenomenon, when the pattern has a narrow opening, a SiO film can be selectively formed and mainly only on the top surface. The operable range of the aspect ratio and the opening size suitable for the above operation varies depending on the deposition conditions such as the deposition pressure and the RF power.

[0010] On the surface of the underlying SiO film on which the SiN film is deposited, -NH end groups are formed by anisotropic or selective incubation or surface nitridation. As a precursor for depositing the SiN film, any precursor capable of being adsorbed on the underlying SiO film having an exposed Si-NH surface but hardly adsorbed on the Si-O surface, such as SiCl4, Si2Cl6, etc., can be used.

[0011] After the SiN film is converted into a SiO film by the oxidation treatment, as necessary, the patterned structure can be subjected to wet etching using, for example, dHF so that any SiO film remaining on the sidewall as a residue can be removed, thereby forming a complete TS-SiO film. Although in principle the SiN film is deposited only on the top surface, the surface selectivity of the precursor for depositing the SiN film, i.e., selective deposition on the Si-NH surface but not on the Si-O surface, can not be perfect. In this case, the SiN film can be deposited slightly on the sidewall, which is converted into a SiO film since oxidation occurs anisotropically. By subjecting the patterned structure to wet etching, the SiO film remaining on the sidewall can be removed. It should be noted that the wet etching rate of the reference thermal oxide film is 1, and the wet etching rate of the SiO film is about 2.2, which is substantially or mostly equal regardless of the position, i.e., the wet etching rate of the top portion of the SiO film, the wet etching rate of the sidewall portion of the SiO film, and the wet etching rate of the bottom portion of the SiO film. Thus, although the wet etching etches not only the sidewall portion of the SiO film but also the top portion of the SiO film, since the top portion of the SiO film is mainly or substantially thicker than the sidewall portion thereof, a complete TS-SiO film can be obtained.

[0012] In some embodiments, the precursor used to deposit the SiN film is carbon-free, and the final silicon oxide film is carbon-free, whereby dispersion of impurities, including carbon migrating from the SiN film to the interface between the SiN film and the underlying film, can be avoided. After the SiN film is converted to a SiO film, a SiO film that is also carbon-free can be formed. By forming a carbon-free SiO film, any impurities such as carbon migrating from the SiO film can be prevented from entering the underlying film through the interface between the SiO film and the underlying film, thereby avoiding degradation of the underlying film.

[0013] Some embodiments feature the use of inorganic carbon-free precursors containing halogen and carbon-free reactants. Conventionally, when using precursors containing halogen, deposition is carried out with the aid of a reactant that is a nitrogen-containing hydrocarbon (linear or cyclic), such as pyridine, in which the nitrogen replaces the halogen bonded to silicon (e.g., Cl-Si) in the precursor adsorbed on the substrate through an exchange reaction (e.g., ) to form 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 precursors containing halogen and carbon-free reactants, a carbon-free SiN film can be deposited by PEALD, followed by a conversion process in which the SiN film is converted to a SiO film by oxidation treatment.

[0014] When the above process is repeated to form a SiO film having a desired thickness, if the adsorption of the carbon-free precursor on the SiO surface is insufficient, resulting in a decrease in growth per cycle (GPC) and / or a decrease in step coverage, the SiO surface can be exposed to a plasma of NH3, N2 / H2, etc. before the process of depositing the SiN film (i.e., before feeding the precursor) to improve the adsorption of the precursor on the substrate surface.

[0015] The topography-selective treatment technique is not limited to the above embodiments. The topography-selective treatment technique is a technique that essentially combines the formation of a nitride film using a halogen-containing silicon-containing precursor by PEALD with oxidation of the nitride film, including in some embodiments the following three techniques:

[0016] 1) deposition of a thin SiO film on a patterned substrate by ALD or CVD, followed by deposition of a SiN film by PEALD using a halogen-containing precursor by manipulating or adjusting the RF power, in which the SiN film selectively grows on the horizontal plane, particularly the top surface, of the patterned substrate due to an anisotropic incubation or surface nitridation process, in which the horizontal plane receives more ion energy than the vertical plane, and the surface nitridation occurs substantially only or primarily on the horizontal plane, not the vertical plane;

[0017] 2) depositing a SiN film on a patterned substrate using a halogen-containing precursor by ALD (thermal or plasma enhanced), then converting the SiN film into a SiO film using an oxidizing material such as O2 with the aid of plasma energy, UV light energy, thermal energy, or other energy, then performing a wet etch, wherein by depositing the SiN film by applying an RF power of 100 to 1,000 W for five seconds or less, the nitridation of a portion of the film deposited on the sidewall becomes incomplete, and the resistance of this portion to the wet etch becomes insufficient, thereby removing a portion of the film on the sidewall by the wet etch and leaving a portion of the film deposited on the horizontal plane; and

[0018] 3) in the above 2), by applying an RF power of 100 to 1,000 W for more than five seconds when depositing the SiN film, the film properties such as wet etch resistance can be made substantially equal between a portion of the film deposited on the top surface, a portion of the film deposited on the sidewall, and a portion of the film deposited on the bottom surface, whereby after the wet etch, a conformal SiO film (carbon-free) can be formed. In the present disclosure, although the RF power for a 300 mm substrate is indicated, when the RF power is used for a substrate having a different diameter, the RF power suitable for this substrate can be determined by calculating the wattage per unit area of the substrate (W / cm 2 ).

[0019] In some embodiments, the precursor is selected from carbon-free, halogen-containing silane-based compounds, and the reactant (nitriding gas) is selected from 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, diiodosilane, dichlorosilane, hexachlorodisilane, and octachlorotrisilane, which can be used alone or in any combination of two or more of the foregoing.

[0021] In some embodiments, the nitriding (replacing halogen with nitrogen by exchange reaction) and oxidizing are sequentially and continuously performed in the same reaction chamber, wherein after the nitriding, the reaction chamber is purged using an inert gas, then an oxidizing gas such as O2, O3, CO2, N2O, H2O, or a combination of two or more of the foregoing is fed into the reaction chamber and oxidized, thereby forming a SiO film.

[0022] In some embodiments, the nitriding and oxidizing do not need to be repeated the same number of times, but by adjusting and changing the number of repetitions of the nitriding and oxidizing and adjusting the RF power, the wet etch resistance of the film can be reduced (for example, by increasing the number of repetitions of the oxidizing, reducing the RF power of the nitriding, and / or increasing the RF power of the oxidizing).

[0023] In some embodiments, by adjusting the wet etching resistance (wet etching rate) of the film formed on the top surface, sidewall, and bottom surface, respective portions of the top surface, sidewall, and bottom surface can be selectively removed or maintained by wet etching (e.g., using dHF).

[0024] In some embodiments, when nitridation and oxidation are performed by PEALD, sometimes, the degree of adsorption of the precursor on the substrate surface is lowered at the time of oxidation, in which case, by improving the surface conditions of the substrate at the time of oxidation using a reducing gas containing hydrogen 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 the present disclosure, unless otherwise stated, SiN, SiO, SiOC, etc. are abbreviations for film types expressed in a non-stoichiometric manner.

[0026] For purposes of summarizing the aspects of the application and the advantages achieved over the related art, certain objects and advantages of the application are described in this disclosure. Of course, it is to be understood that not necessarily all such objects or advantages can be achieved in accordance with any particular embodiment of the application. Accordingly, for example, those skilled in the art will recognize that the application can be practiced with

[0027] Other aspects, features, and advantages of the present application will become apparent from the following detailed description. BRIEF DESCRIPTION OF DRAWINGS

[0028] These and other features of the present application will now be described with reference to the attached drawings, which are meant to be illustrative only and not limiting in any way.

[0029] Figure 1A 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 application.

[0030] Figure 1B A schematic diagram of a precursor supply system using a flow through system (FPS) that can be used in one embodiment of the present application is shown.

[0031] Figure 2 A flowchart showing a process for topologically selective film formation according to one embodiment of the present application.

[0032] Figure 3 A flowchart showing a process for topologically selective film formation according to another embodiment of the present application.

[0033] Figure 4 is a flow chart showing a process of topographically selective film formation according to another embodiment of the application.

[0034] Figure 5 is a flow chart showing a process of topographically selective film formation according to another embodiment of the application.

[0035] Figure 6 is a timing diagram showing a sequence of processes of topographically selective film formation according to one embodiment of the application, where the width of each column does not necessarily represent the actual time duration, and the raising of a line in each row represents an on state, while the lowering of a line in each row represents an off state.

[0036] Figure 7 is a diagram showing a sequence of processes of topographically selective film formation according to another embodiment of the application, where the grayed cells represent an on state, while the white cells represent an off state, and the width of each column does not represent the duration of each process.

[0037] Figure 8 is a diagram showing a sequence of processes of film formation according to a conventional process, where the grayed cells represent an on state, while the white cells represent an off state, and the width of each column does not represent the duration of each process.

[0038] Figure 9 is a schematic cross-sectional view showing a process of topographically selective film formation according to one embodiment of the application.

[0039] Figure 10 is a schematic cross-sectional view showing a process of topographically selective film formation according to another embodiment of the application.

[0040] Figure 11 is a schematic cross-sectional view showing a process of topographically selective film formation according to another embodiment of the application. DETAILED DESCRIPTION

[0041] In the present disclosure, "gas" can include vaporized solids and / or liquids and can be composed of a single gas or a mixture of gases. In the present disclosure, a process gas introduced into a reaction chamber through a showerhead can contain, consist essentially of, or consist of a precursor gas and an additive gas. The precursor gas and the additive gas are typically introduced into the reaction space as a mixed gas or separately. The precursor gas can be introduced with a carrier gas, such as a noble gas. The additive gas can contain, consist essentially of, or consist of a reactive gas and a dilution gas, such as a noble gas. The reactive gas and the dilution gas can be introduced into the reaction space as a mixed gas or separately. The precursor can contain two or more precursors, and the reactive gas can contain two or more reactive gases. The precursor is a gas that chemisorbs on a substrate and typically contains a metalloid or metallic element that forms the main structure of the dielectric film matrix, and the reactive gas used for deposition is a gas that reacts with the precursor chemisorbed on the substrate when the gas is excited to fix an atomic layer or monolayer on the substrate. "Chemisorption" refers to chemically saturated adsorption, which can also be simply referred to as "adsorption." A gas other than the process gas, i.e., a gas that is not introduced through the showerhead, can be used, for example, to seal the reaction space, which includes a seal gas, such as a noble gas. In some embodiments, "film" refers to a substantially pinhole-free layer that extends continuously in a direction perpendicular to the thickness direction to cover an entire target or relevant surface, or simply refers to a layer that covers a target or relevant surface. In some embodiments, "layer" refers to a structure formed on a surface with a certain thickness, or a synonym for a film or non-film structure. A film or layer can be composed of a discrete single film or layer with certain characteristics or of multiple films or layers, and the boundary between adjacent films or layers can or can not be transparent, and can be established based on physical, chemical, and / or any other characteristics, formation processes or sequences, and / or the function or purpose of the adjacent films or layers.

[0042] In the present disclosure, "containing Si-O bonds" can refer to being characterized by one or more Si-O bonds, having a main backbone consisting essentially of one or more Si-O bonds, and / or having substituents consisting essentially of one or more Si-O bonds. SiO films, SiOC films, and SiON films containing Si-O bonds include, but are not limited to, SiO films, SiOC films, and SiON films having a dielectric constant of about 2 to 10, typically about 4 to 8.

[0043] Further, in the present disclosure, the articles "a" and "an" refer to one or more unless otherwise indicated by the context. In some embodiments, the terms "comprising," "including," "containing," "consisting of," and "consisting essentially of," refer to "generally includes or comprises, " "includes," "consists essentially of," or "consists of," independently. Additionally, in the present disclosure, in some embodiments, any defined meaning is not necessarily mutually exclusive of the ordinary and customary meaning.

[0044] Additionally, in the present disclosure, since the workable range can be determined based on routine work, any two numbers of a variable can constitute the workable range of the variable, and any range indicated can include or exclude the endpoints. Additionally, any indicated variable values, whether or not they are indicated with "about," can refer to exact or approximate values and include equivalent values, and in some embodiments can refer to average values, median values, representative values, majority values, etc.

[0045] In the present disclosure, when conditions and / or structures are not specified, one skilled in the art can readily provide such conditions and / or structures according to the present disclosure, following routine experimentation. In all disclosed embodiments, any element used in one embodiment can be replaced with any equivalent element, including those explicitly, necessarily or inherently disclosed herein, for predetermined purposes. Furthermore, the present invention can be equally applicable to apparatuses and methods.

[0046] Embodiments will be described with reference to the preferred embodiments. However, the present invention is not limited to the preferred embodiments.

[0047] One exemplary embodiment relates to a dielectric film formation process based on PEALD technology, in which substantially only or mainly horizontal faces of a patterned template are surface treated by using anisotropic surface treatment of plasma, and then a film is selectively grown on the surface treated faces. The growth of the film mainly occurs in the vertical direction, while the film growth in the horizontal direction is suppressed, thereby obtaining a film profile with a desired topology. By this technology, between the top face of the substrate and the sidewalls of the recesses of the substrate, a film can be substantially only deposited on the top face of the substrate. The term "substantially only" refers to, for example, 70%, 80%, 90% or 95% or more of the total amount, for example, a ratio of an average thickness of a portion of the film deposited on the top face to an average thickness of a portion of the film deposited on the sidewalls is 7 / 3 or more.

[0048] For example, although the bottom face is also a horizontal face, the extent of film formation on the bottom face depends on the aspect ratio. If the aspect ratio of the trench is high, for example, 3 or more when the opening size is 50 nm or less, the number of ions entering the trench becomes very low compared to the top face exposed to ion bombardment. Therefore, the progress of surface nitridation or incubation on the bottom face by surface treatment (nitridation treatment of SiO surface) is not as much as that on the top face, and thus the thickness of the film grown on the bottom face is smaller than that of the film grown on the top face. By adjusting the aspect ratio of the recess, for example, using a recess with an aspect ratio of 10 or more, between the top face, the sidewall, and the bottom face, a film can be substantially deposited on the top face.

[0049] In some embodiments, the topographically selective process includes: A) anisotropic surface treatment (incubation or surface nitridation) using plasma in a manner that substantially only processes the horizontal faces of the patterned substrate; B) deposition of a nitride film on the surface treated faces by PEALD using a plasma containing a halogen active group containing precursor and NH3, N2 / H2, etc. (nitridation by exchange reaction between halogen and nitrogen); C) conversion of the nitride film to an oxide film by changing the gas in the reaction chamber to an oxidizing atmosphere by introducing, for example, O2 after purging the reaction chamber, and oxidizing the nitride film by, for example, thermal oxidation, radical oxidation, plasma oxidation, etc.; and D) repeating steps A) to C) until the thickness of the oxide film reaches the desired value, wherein the oxide film has the desired topographically selective film profile.

[0050] In some embodiments, the oxide film is composed of SiO, SiOC, SiON, etc. Due to the anisotropic surface treatment, the film grows substantially only in the vertical direction and not in the horizontal direction. By using a recess with a high aspect ratio, between the top face, sidewall, and bottom face, the film can be formed substantially only on the top face. Further, as desired, by performing an isotropic wet etch (e.g., using dHF) on the final deposited oxide film, the film on the sidewall can be completely removed, thereby forming a film profile in which only the film on the top and bottom faces can remain. Further, in some embodiments, the surface treatment and deposition processes can be performed consecutively using the same reaction chamber.

[0051] In topographically selective processing techniques, a carbon-free SiO film grown on a substrate can be formed by depositing a SiN film using a carbon-free precursor and a carbon-free nitridation reagent such as N2, N2 / H2, NH3, etc., and then converting the SiN film to a SiO film by oxidizing the SiN film using an oxidizing gas such as O2, H2O, etc. by an oxidation exchange reaction. By this technique, while the formation of the SiO film is being performed, the accumulation of impurities contained in the process gases (including the precursor and the reagent) on the interface between the SiO film and the underlying film can be suppressed.

[0052] Some embodiments provide a method for forming a silicon oxide film on a staircase formed on a substrate having a top surface, a sidewall, and a bottom surface, comprising the following processes: (a) designing a topography of a final silicon oxide film, which is a conformal film or a film with low conformality, by pre-selecting a target portion of an initial silicon nitride film, with reference to a non-target portion of the initial silicon nitride film, to selectively deposit or remove or restructure to produce the final silicon oxide film on the staircase, the selectively deposited target portion being a top / bottom portion of the initial silicon nitride film formed on the top and bottom surfaces of the staircase, the selectively removed or restructured target portion being a sidewall portion of the initial silicon nitride film formed on the sidewall of the staircase; and (b) forming the initial silicon nitride film and the final silicon oxide film on the surfaces of the staircase according to the topography designed in process (a), wherein the initial silicon nitride film is deposited by atomic layer deposition (ALD) using a silicon-containing precursor containing halogen, the initial silicon nitride film is converted into the final silicon oxide film by oxidizing the initial silicon nitride film without further depositing the film, wherein the Si-N bonds in the initial silicon nitride film are converted into Si-O bonds. Figure 2 is a flow chart representing the above topography selective film formation process. As shown in Figure 2 there are three techniques used alternatively or in any combination to achieve the desired topography of the final oxide film: selectively depositing a target portion of the film, selectively removing a target portion of the film, and selectively restructuring a target portion of the film.

[0053] In the present disclosure, the term “staircase” or “trench” refers to any patterned structure composed of a riser (sidewall) and a tread (top surface) relative to a reference plane (bottom surface) formed in a substrate, and in some embodiments, the staircase can be a trench having a width of about 10 to about 50 nm (typically about 15 to about 30 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), where when the length of the trench is substantially the same as the width, it is referred to as a hole / via having a diameter of about 10 to about 50 nm. In some embodiments, the final silicon oxide film is selectively formed on the top surface (with a conformality of about 0 to about 10%, about 20%, or about 30% or lower) or uniformly formed along the staircase or trench of the substrate (with a conformality of about 70% to about 110%, typically about 80% or higher, more typically about 90% or higher, and 100% or lower), where “conformality” is determined by comparing the film thickness formed at a certain point (typically a middle point in a cross-sectional view) on the sidewall or bottom surface of the trench and the film thickness formed on the planar surface (top surface) outside the trench.

[0054] In some embodiments, the precursors used in process (b) do not contain carbon, and the final silicon oxide film does not contain carbon.

[0055] In some embodiments, the formation of the initial silicon nitride film (which can be referred to as "nitridation", where the nitrogen of the reactant replaces the halogen of the absorbed precursor through an exchange reaction) and the oxidation of the initial silicon nitride film are performed consecutively in the same reaction space in process (b). In some embodiments, after the initial silicon nitride film is formed, the reaction space is purged before the initial silicon nitride film is oxidized, and the oxidation of the initial silicon nitride film is plasma oxidation in the reaction space with the introduction of an oxidizing gas, which is at least one gas selected from the group consisting of O2, O3, CO2, N2O, and H2O. In the present disclosure, "consecutively" means without breaking the vacuum, without interruption in the timeline, without changing the processing conditions, immediately after, as the next step, or in some embodiments, without a discrete physical or chemical boundary between the two structures. Nitridation is generally required to be substantially complete, as any remaining halogen in the nitride film can be considered an impurity, like carbon, which can migrate to the interface between the nitride film and the underlying film.

[0056] In some embodiments, the initial silicon nitride film is composed of multiple monolayers, and in process (b), the oxidation of the initial silicon nitride film is performed after each monolayer deposition cycle of the ALD of the initial silicon nitride film or after each multiple monolayer deposition cycle of the ALD of the initial silicon nitride film.

[0057] In some embodiments, the pre-selected target portion in process (a) is a target portion for selective deposition, wherein process (b) comprises: (ci) depositing a silicon oxide film on the stepped surface on the substrate; (cii) placing the substrate between two electrodes in parallel with the two electrodes to anisotropically nitridate the surface of the silicon oxide film in a manner that primarily nitridates the top and bottom surfaces of the steps but not the sidewalls of the steps using a nitrogen-containing hydrogen plasma generated by applying RF power between the two electrodes, thereby

[0058] introducing -NH end groups on 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 ALD using a precursor and a nitridation gas excited by a plasma generated by applying RF power between the two electrodes; (civ) oxidizing at least a portion of the initial silicon nitride film using an excited oxidizing gas to obtain at least a portion of a final silicon oxide film without further deposition of a film, wherein the Si-N bonds in the initial silicon nitride film are converted to Si-O bonds; and (cv) repeating processes (cii) and (civ) as needed until a final silicon oxide film having a desired thickness is obtained. Figure 3 is a flow chart representing the above-described topologically selective film formation process.

[0059] In some embodiments, the nitrogen-containing hydrogen plasma in process (cii) uses a mixture of N2 and H2, NH3, other N x Hy generated, where x and y are integers, or a mixture of two or more of the foregoing.

[0060] In some embodiments, the silicon oxide film in process (ci) is deposited by ALD or CVD.

[0061] In some embodiments, the preselected target portions in process (a) are target portions for selective removal, wherein process (b) comprises: (di) depositing at least a portion of an initial silicon nitride film on the surface of the step by ALD using a precursor and a reactant gas excited by plasma generated by applying RF power between two electrodes, the substrate being placed parallel to the two electrodes between the two electrodes, wherein in each monolayer deposition cycle of the ALD, the RF power is applied at 0.14 W / cm 2 to 1.41 W / cm 2 for five seconds or less, thereby making the target portions less chemically resistant than the non-target portions when subjected to wet etching; (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 further deposition of the film, wherein the Si-N bonds in the initial silicon nitride film are converted to Si-O bonds; and (diii) repeating processes (di) and (dii) as needed until an intermediate silicon oxide film having a desired thickness is obtained; then (div) wet etching the intermediate silicon oxide film to obtain a final dielectric film, thereby primarily removing the target portions with reference to the non-target portions. Figure 4 is a flowchart representing the above-described topologically selective film formation process.

[0062] In some embodiments, the oxidizing in process (dii) is performed using plasma, UV light, heat, or a combination of two or more of the foregoing.

[0063] In some embodiments, the RF power used in process (di) is 0.14 W / cm 2 to 0.71 W / cm 2 of the substrate per unit area, the substrate being placed parallel to the two electrodes between the two electrodes. 2 to 0.71 W / cm 2 of the substrate per unit area, the substrate being placed parallel to the two electrodes between the two electrodes.

[0064] In some embodiments, process (diii) is performed, wherein prior to each time process (di) is about to be repeated, the surface of the step of the substrate is exposed to a hydrogen-containing reducing gas to treat the surface with the hydrogen-containing reducing gas.

[0065] In some embodiments, the hydrogen-containing reducing gas is at least one gas selected from the group consisting of H2 and NH3.

[0066] In some embodiments, in process (div), the wet etching is a wet etching using dHF.

[0067] In some embodiments, the pre-selected target portion in process (a) is a target portion for selective reforming, wherein process (b) comprises: (ei) depositing at least a portion of an initial silicon nitride film on the surface of the step on the substrate using a precursor and a reaction gas excited by a plasma generated by applying RF power between two electrodes, the substrate being placed parallel to the two electrodes between the two electrodes, wherein in each monolayer deposition cycle of the ALD, the RF power is applied at 0.14 W / cm 2 to 1.41 W / cm 2 for more than five seconds, such that when the wet etching is performed, the chemical resistance of the target portion is substantially equal to the chemical resistance of the non-target portion; (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 further deposition of the film, wherein the Si-N bonds in the initial silicon nitride film are converted to Si-O bonds; and (eiii) repeating processes (ei) and (eii) as needed until the intermediate silicon oxide film having a desired thickness is obtained; then (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 representing the above-described topologically selective film formation process.

[0068] In some embodiments, the oxidizing in process (eii) is performed using plasma, UV light, heat, or a combination of two or more of the foregoing.

[0069] In some embodiments, the RF power used in process (ei) is 0.71 W / cm 2 to 1.41 W / cm 2 and the oxidizing in process (eii) is plasma oxidation after each monolayer deposition cycle of the ALD of the initial silicon nitride film in process (ei) or after each multiple monolayer deposition cycle of the ALD of the initial silicon nitride film, wherein the plasma is generated by applying RF power between two electrodes at 0.07 W / cm 2 to 0.71 W / cm 2The substrate is placed parallel to the two electrodes between the two electrodes.

[0070] In some embodiments, process (eiii) is performed, wherein prior to each repetition of process (ei), the surface of the step of the substrate is exposed to a hydrogen-containing reducing gas to treat the surface with the hydrogen-containing reducing gas.

[0071] In some embodiments, the hydrogen-containing reducing gas is at least one gas selected from the group consisting of H2and NH3.

[0072] In some embodiments, in process (eiv), the wet etching is a wet etching using dHF.

[0073] In some embodiments, the etching is a wet etching using dHF at a concentration of about 0.1%.

[0074] The present application will be described in detail with reference to preferred embodiments shown in the attached drawings. However, the present application is not intended to be limited to these embodiments.

[0075] Figure 6 To show the timing chart of the process sequence of the top-selective film formation according to one embodiment of the present application, wherein the width of each column does not necessarily represent the actual time length, the raising of the line in each row represents the on state, and the sinking of the line in each row represents the off state. By this technique, a top-thick TS-SiO film can be formed by selectively depositing the target portion (top portion) of the film.

[0076] In Figure 6 In the selective deposition of the target portion (top portion) of the film, three processes are involved: an incubation process, a nitridation (deposition) process, and an oxidation process. Prior to the incubation process, a silicon oxide film is deposited as a bottom film on the step surface on the patterned substrate. The incubation process involves placing the substrate parallel to the two electrodes between the two electrodes, anisotropically nitriding the surface of the silicon oxide film using a nitrogen-containing hydrogen plasma generated by applying RF power (process 3) between the two electrodes with a nitridation gas (reactant 1) in such a way that the surface of the silicon oxide film is nitrided mainly on the top and bottom surfaces of the step but not on the sidewalls of the step, thereby introducing -NH end groups on the surface of the silicon oxide film. In the incubation process, in some embodiments, the flow rate of reactant 1 is in the range of 500 sccm to 10000 sccm (preferably 1000 sccm to 5000 sccm), and process 3 is in the range of 1 second to 20 seconds (preferably 3 seconds to 10 seconds).

[0077] Next, a nitridation (deposition) process is started, which includes using a precursor and a nitridation gas (reactant 1) excited by plasma generated by applying RF power between two electrodes (process 1) to deposit at least a part of an initial silicon nitride film on the surface-treated silicon oxide film by PEALD and to contact therewith. Both the process 3 in the incubation process and the process 1 in the nitridation process are processes by applying RF power. Although the conditions of RF power application in the process 3 and the process 1 can be the same. However, in some embodiments, it is preferable that the process 3 uses stronger ion energy than the process 1 to perform anisotropic surface nitridation. Therefore, in some embodiments, in the process 3, higher RF power and / or lower pressure than in the process 1 are used. For example, in the process 3, RF power in the range of 0.07 W / cm 2 to 1.4 W / cm 2 (0.14 W / cm 2 to 0.7 W / cm 2 ) is applied at a pressure of 100 Pa to 3000 Pa (preferably 200 Pa to 1000 Pa), while in the process 1, RF power in the range of 0.07 W / cm 2 to 1.4 W / cm 2 (0.14 W / cm 2 to 0.7 W / cm 2 ) is applied at a pressure of 100 Pa to 2000 Pa (preferably 200 Pa to 1000 Pa). The nitridation (deposition) process is a PEALD process in which one cycle for forming a monolayer can be repeated N times until a nitride film of a desired thickness is obtained, where N is an integer of 10 to 1000 (preferably 10 to 30), depending on the intended use of the film and the like, so as to deposit a nitride film having a thickness of 5 nm to 100 nm (preferably 10 nm to 30 nm). In one cycle of PEALD, the durations of the pulse of the precursor, the pulse of the reactant 1, and the pulse of the process 1 are in the range of 0.1 seconds to 20 seconds.

[0078] Thereafter, the oxidation process includes oxidizing (process 2) at least a part of the initial silicon nitride film using an oxidation gas (reactant 2) excited by RF power to obtain at least a part of a final silicon oxide film without further depositing a film, in which the Si-N bonds in the initial silicon nitride film are converted to Si-O bonds. For example, in the process 2, 0.07 W / cm 2 to 1.4 W / cm 2 (0.07 W / cm 2 to 0.7 W / cm 2The RF power is within the range of 10 sccm to 1000 sccm (preferably 50 sccm to 500 sccm) 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).

[0079] Throughout the process, inert gas is continuously fed into the reaction chamber in the range of 500 sccm to 10000 sccm (preferably 1000 sccm to 5000 sccm). Additionally, the process temperature can be in the range of 0°C to 600°C (preferably 200°C to 500°C).

[0080] Furthermore, the incubation process, nitriding process, and oxidation process can be repeated M times as needed until a final silicon oxide film with the desired thickness is obtained, where M is an integer from 1 to 30 (preferably 1 to 15), depending on the intended use of the film, etc.

[0081] Figure 9 A schematic cross-sectional view is shown, which illustrates the situation according to... Figure 6 The timing diagram shown illustrates a topologically selective film formation process for one embodiment. State (a) represents the state prior to state (b), where a SiO film 43 is formed on the surface of a substrate 41 having steps 42 (trenches). State (b) represents the state during the incubation process, where the surface of the SiO film 43 is anisotropically nitrided with nitrogen-containing plasma to introduce -NH end groups onto the SiO surface, thereby forming a SiNH surface 44 on the SiO film 43. State (c) represents the state during the nitriding process, where a SiN film 46 is deposited and grown on the SiNH surface 44 via PEALD. When the SiN film 46 undergoes an oxidation process, the SiN film 46 is transformed into a SiN film similar to the SiN film 43 in state (a). These processes are then repeated to obtain the desired final SiO film (top-thickness TS-SiO film) on the substrate.

[0082] In some embodiments, selective deposition schemes can be performed under the conditions shown in Table 1 below.

[0083] Table 1 (Values ​​are approximate)

[0084]

[0085] Figure 7To show a process sequence of top-selective film formation according to another embodiment of the present application, in which a gray cell represents an ON state and a white cell represents an OFF state, and the width of each column does not represent the duration of each process. By this technique, a top-thick TS-SiO film can be formed by selectively removing a target portion (a sidewall) of a film, and a conformal TS-SiO film can also be formed by selectively re-forming a target portion (a top surface with respect to a sidewall) of a film.

[0086] The process sequence includes a nitridation / deposition process ("Feed-In" → "Purge" → "RF Pulse-1 (Nitridation / Reduction)" → "Purge"), an oxidation process ("Reagent-2 In" → "RF Pulse-2 (Oxidation)" → "Purge"), and a wet etching process ("DHF Dip"). The nitridation process includes depositing at least a portion of an initial silicon nitride film on a stepped surface on a substrate by PEALD using a precursor (Si precursor) and a reactant gas (Reagent-1) excited by plasma generated by applying RF power (RF) between two electrodes, the substrate being placed parallel to the two electrodes between the two electrodes, wherein in each single layer deposition cycle of PEALD, the RF power is applied at 0.14 W / cm 2 to 1.41 W / cm 2 (preferably 0.07 W / cm 2 to 0.71 W / cm 2 for a time of five seconds or less (preferably 1 to 3 seconds), thereby making the chemical resistance (wet etching resistance) of the target portion (sidewall) lower than that of the non-target portion when wet etching is performed. By using the above RF power application conditions, a portion of the film deposited on the sidewall is not sufficiently nitrided to maintain resistance to wet etching compared to a portion of the film deposited on the top / bottom surface, thereby allowing the sidewall portion to be selectively removed by wet etching.

[0087] The nitridation (deposition) process is a PEALD process, wherein one cycle for forming a monolayer can be repeated q times until a nitride film of a desired thickness is obtained, wherein q is an integer from 10 to 1000 (preferably 30 to 500), depending on the intended use of the film, etc., so as to deposit a nitride film having a thickness of 5 nm to 100 nm (preferably 10 nm to 30 nm). In one cycle of PEALD, the duration of the pulse of "Si-precursor", the pulse of "reactant-1", and the pulse of "RF" is in the range of 0.1 seconds to 20 seconds (preferably 0.1 seconds to 10 seconds). In some embodiments, the RF power is applied at a pressure of 100 Pa to 2000 Pa (preferably 200 Pa to 1000 Pa). In the nitridation process, in some embodiments, the flow rate of reactant-1 is in the range of 500 seem to 10000 seem (preferably 2000 seem to 5000 seem). In this embodiment, "reactant-1" and "carrier gas / dilution gas" are continuously flowed.

[0088] Next, an oxidation process is started, which includes 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 deposition of the film, wherein the Si-N bonds in the initial silicon nitride film are converted to Si-O bonds. For example, an RF power in the range of 0.07 W / cm 2 to 1.4 W / cm 2 (preferably 0.07 W / cm 2 to 0.7 W / cm 2 ) is applied at 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 seem to 1000 seem (preferably 50 seem to 500 seem), and the duration of "RF" is in the range of 0.1 seconds to 10 seconds (preferably 0.1 seconds to 5 seconds).

[0089] Throughout the process, a carrier gas and / or a dilution gas can be continuously fed into the reaction chamber in the range of 500 seem to 10000 seem (preferably 1000 seem to 5000 seem). In addition, the temperature of the process can be in the range of 0 °C to 600 °C (preferably 200 °C to 500 °C).

[0090] Further, the nitridation / deposition process and the oxidation process are repeated p times as needed until an intermediate silicon oxide film having a desired thickness is obtained, wherein p is an integer from 1 to 30 (preferably 1 to 15), depending on the intended use of the film, etc.

[0091] Thereafter, a wet etching process (DHF dip) is initiated, which involves wet etching the intermediate silicon oxide film to obtain a final dielectric film, thereby primarily removing the target portion (sidewall) with reference to the non-target portion. In some embodiments, the wet etching can be performed by etching the substrate using hydrofluoric acid diluted to 0.1% to 1.5% or its known or new suitable equivalents / substitutes at a temperature of 15°C to 25°C for 30 seconds to 600 seconds.

[0092] Figure 10 A schematic cross-sectional view is shown, which illustrates a topologically selective film formation process according to one embodiment represented by the process sequence shown in Figure 7 State (a) represents the state at the time of the nitridation / deposition process, in which a SiN film 53 is formed on the surface of a substrate 51 having a staircase 52 (trench). State (b) represents the state at the time of the oxidation process, in which the SiN film 53 is subjected to an oxidation process, and the SiN film 53 is converted into a SiO film 54. Thereafter, the nitridation / deposition process and the oxidation process are repeated as necessary until a SiO film of the desired thickness is obtained. State (c) represents the state at the time of the wet etching, in which by wet etching, the sidewall portion of the film can be selectively significantly removed or selectively completely removed, while the other portion can be maintained at a significant thickness, since the portion of the film deposited on the sidewall has a lower wet etching resistance than the portion of the top surface / bottom surface. Thus, a desired final SiO film (top thick TS-SiO film) can be formed on the substrate.

[0093] By using the same process shown in Figure 7 except that the RF power applied between the two electrodes is 0.14 W / cm 2 to 1.41 W / cm 2 (0.07 W / cm 2 to 0.71 W / cm 2 ) per unit area of the substrate for more than five seconds in each single layer deposition cycle of the ALD, the film properties such as the wet etching resistance of the resulting SiO film can become substantially equal between 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, whereby after the wet etching, a conformal SiO film (carbon-free) can be formed.

[0094] Figure 11 A schematic cross-sectional view is shown, which illustrates a topologically selective film formation process according to one embodiment represented by the process sequence shown in Figure 7The process sequence shown represents a topological topologically selective film formation process, which is modified as discussed above. State (a) represents the state at the time of 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 at the time of oxidation process, in which the SiN film 63 is subjected to an oxidation process, and the SiN film 63 is converted to a SiO film 64. Thereafter, the nitridation / deposition process and the oxidation process are repeated as necessary until a SiO film of a desired thickness is obtained. State (c) represents the state at the time of wet etching, in which by wet etching, since 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 the wet etching, all of the portions are etched substantially equally as necessary. Thus, a desired final SiO film (conformal carbon-free, uniform TS-SiO film) can be formed on the substrate.

[0095] In some embodiments, the nitridation in the selective removal of the target portion Figure 10 and the selective reforming of the target portion Figure 11 may be performed under the conditions shown in Table 2 below.

[0096] Table 2 (values are approximate)

[0097]

[0098] In some embodiments, in the selective reforming scheme, in order to improve the conformality of the film, the flow rate of the nitrogen-containing gas is greater than in the selective removal scheme, and the RF power application time is also longer than in the selective removal scheme. In other words, in some embodiments, in the selective removal scheme, in order to improve the growth of the film on a flat (horizontal) surface relative to on a vertical surface, the flow rate of the nitrogen-containing gas is less than in the selective reforming scheme, and the RF power application time is also shorter than in the selective reforming scheme.

[0099] Figure 8 A diagram showing a conventional process sequence for film formation, in which the gray cells represent an on state, and the white cells represent an off state, and the width of each column does not represent the duration of each process. Since in the conventional process, no process corresponding to or equivalent to the processes discussed above in relation to the embodiments of the present application are performed, logically, a conformal carbon-free, uniform SiO film is not formed.

[0100] In the process sequences described in the present disclosure, the precursors can be supplied in pulses using a continuously supplied carrier gas. This can be achieved using a flow through system (FPS), in which the carrier gas line is provided with a bypass line having a precursor reservoir (bottle), and the main and bypass lines are switched, in which the bypass line is closed when it is intended to feed only carrier gas to the reaction chamber, and the main line is closed when it is intended to feed carrier gas and precursor gas to the reaction chamber, and the carrier gas flows through the bypass line and out of the bottle together with the precursor gas. In this way, the carrier gas can flow continuously into the reaction chamber and can carry the precursor gas in pulses by switching the main and bypass lines. Figure 1B A precursor supply system using a flow through system (FPS) according to one embodiment of the present application is shown (black valves indicate that the valves are closed). As Figure 1B As shown in (a) in FIG. 3, when the precursor is fed to the reaction chamber (not shown), first, a carrier gas such as Ar (or He) flows through the gas line having valves b and c, and then enters the bottle (reservoir) 30. The carrier gas flows out of the bottle 30, while the carrier gas carries the precursor gas corresponding to the vapor pressure inside the bottle 30, and flows through the gas line having valves f and e, and then is fed to the reaction chamber together with the precursor. In the above, valves a and d are closed. When only the carrier gas (noble gas) is fed to the reaction chamber, as shown in (b) in FIG. 3, the carrier gas flows through the gas line having valve a, while bypassing the bottle 30. In the above, valves b, c, d, e, and f are closed. Figure 1B As shown in (a) in FIG. 3, when the precursor is fed to the reaction chamber (not shown), first, a carrier gas such as Ar (or He) flows through the gas line having valves b and c, and then enters the bottle (reservoir) 30. The carrier gas flows out of the bottle 30, while the carrier gas carries the precursor gas corresponding to the vapor pressure inside the bottle 30, and flows through the gas line having valves f and e, and then is fed to the reaction chamber together with the precursor. In the above, valves a and d are closed. When only the carrier gas (noble gas) is fed to the reaction chamber, as shown in (b) in FIG. 3, the carrier gas flows through the gas line having valve a, while bypassing the bottle 30. In the above, valves b, c, d, e, and f are closed.

[0101] The precursors can be provided with the aid of a carrier gas. Since 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 the precursor exposure after saturation, whereby the supply of precursor per cycle is such that the reactive surface sites are saturated. The plasma for deposition can be generated in situ, for example, in a continuous flow of ammonia gas throughout the deposition cycle. In other embodiments, the plasma can be generated remotely and provided to the reaction chamber.

[0102] As mentioned above, each pulse or phase of each deposition cycle is preferably self-limiting. An excess of reactant is supplied in each phase to saturate the sensitive structure surface. Surface saturation ensures that the reactant occupies all available reaction sites (e.g., limited by physical size or "steric" hindrance), thus ensuring excellent step coverage. In some embodiments, the pulse time of one or more reactants can be reduced such that full saturation is not achieved and less than one monolayer is adsorbed on the substrate surface.

[0103] The process cycles can be performed using any suitable apparatus, including, for example Figure 1A the apparatus shown. Figure 1Ais a schematic of a PEALD apparatus, which can be used in some embodiments of the present application, in combination with a control device programmed to carry out the processes described below. In this figure, by providing a pair of parallel and facing each other in the interior 11 (reaction zone) of the reaction chamber 3, conductive flat electrodes 4, 2, HRF power (13.56 MHz or 27 MHz) 20 is applied to one side and the other side 12 is electrically grounded, plasma is excited between the electrodes. A temperature regulator is provided in the lower platform 2 (lower electrode) and the temperature of the substrate 1 placed on it is kept constant at a given temperature. The upper electrode 4 also acts as a shower plate and the reaction gas (and noble gas) and precursor gas are introduced into the reaction chamber 3 through the gas line 21 and the gas line 22, respectively, and through the shower plate 4. In addition, in the reaction chamber 3, an annular tube 13 with an exhaust line 7 is provided, through which the gases in the interior 11 of the reaction chamber 3 are exhausted. In addition, a dilution gas is introduced into the reaction chamber 3 through the gas line 23. Furthermore, the transfer chamber 5 disposed below the reaction chamber 3 is provided with a sealing gas line 24 to introduce a sealing gas into the interior 11 of the reaction chamber 3 via the interior 16 (transfer zone) of the transfer chamber 5, in which an isolation plate 14 is provided for isolating the reaction zone from the transfer zone (gate valves through which the wafer is transferred into or from the transfer chamber 5 are omitted in this figure). The transfer chamber also has an exhaust line 6. In some embodiments, deposition of a multi-element film and surface treatment are carried out in the same reaction space, so that all steps can be carried out continuously without exposing the substrate to air or other oxygen-containing atmosphere. In some embodiments, a remote plasma unit can be used to excite the gases.

[0104] In some embodiments, in the apparatus depicted in Figure 1A In some embodiments, the system (described earlier) schematized in Figure 1B The system schematized in

[0105] In some embodiments, a dual chamber reactor (for processing two parts or compartments of wafers disposed next to each other) can be used, in which the reaction gas and the noble gas can be supplied through a shared line while the precursor gas is supplied through a non-shared line.

[0106] The skilled person will recognize that the apparatus includes one or more controllers (not shown) programmed or otherwise configured to enable the deposition and reactor cleaning processes described elsewhere herein to be carried out. As the skilled person will appreciate, the one or more controllers can be in communication with various power sources, heating systems, pumps, robotic devices, and gas flow controllers or valves of the reactor.

[0107] The application is further explained with reference to the following working examples. However, the examples are not intended to limit the application. In examples where conditions and / or structures are not specified, such conditions and / or structures can readily be provided by one of ordinary skill in the art in light of the present disclosure, following routine experimentation. Additionally, in some embodiments, values applied in a particular example can be modified by a range of at least ±50%, and the values are approximations.

[0108] Example

[0109] Example 1

[0110] In this example, selective reforming of a target portion of a film was performed as shown in FIG. 1. First, a SiN film having a thickness of 20 nm was formed on a Si substrate (Ф300 mm) having a trench (opening of 30 nm, aspect ratio of 3) by PEALD, and then, using a PEALD apparatus as shown in FIG. 2 and a gas supply system (FPS) as shown in FIG. 3, the SiN film was converted into a SiO film under the general conditions shown in Table 3 below and the specific conditions shown in Table 4 below according to the process sequence shown in FIG. 4. Thereafter, the substrate was subjected to wet etching under the conditions shown in Table 3 below. As a comparative example, a SiO film was deposited in a similar manner to the above, in which the nitridation / deposition process and the oxidation (conversion) process were not performed, according to the process sequence shown in FIG. 5. Figure 5 Figure 1A Figure 1B Figure 7 Figure 8

[0111] Table 3 (values are approximations)

[0112]

[0113]

[0114] Table 4 (values are approximations)

[0115]

[0116] Each SiO film was evaluated and the results are shown in Table 5 below.

[0117] Table 5 (values are approximations)

[0118]

[0119]

[0120] ​​​​​In Table 5, "Saturation" in "GPC Trend by Purge Time" means that the purge process is in a manner of a reaction process of each cycle of PEALD with saturation of adsorbed precursors; "Side Coverage" refers to conformality (%); "PLE" refers to the ratio of narrow size and wide size; "100:1 DHF-WERR (TOX Ratio)" refers to the wet etch rate relative to a thermal oxide film using diluted 1% hydrofluoric acid; "<5" in "Carbon" means that the detected carbon is less than 5 atomic %; "ND" means "not detected".

[0121] As shown in Table 5, according to the examples, the SiO films obtained in all examples are high-quality conformal carbon-free SiO films, while in the comparative example, the SiO film is a lower-quality SiOC film.

[0122] Those skilled in the art will appreciate that modifications can be made without departing from the spirit of the application. Therefore, it is to be understood that the forms of the application are illustrative only and that the application is not limited to the specific forms set forth.

Claims

1. A method for forming a silicon oxide film on a staircase formed on a substrate having a top surface, sidewalls and a bottom surface, comprising the following processes: (a) designing a topography of a final silicon oxide film, which is a conformal film or a film with low conformality, by pre-selecting a target portion of an initial silicon nitride film, referring to a non-target portion of the initial silicon nitride film, selectively depositing or removing or reforming to produce the final silicon oxide film, the selectively deposited target portion being a top / bottom portion of the initial silicon nitride film formed on the top and bottom surfaces of the staircase, the selectively removed or reformed target portion being a sidewall portion of the initial silicon nitride film formed on the sidewalls of the staircase; and (b) forming the initial silicon nitride film and the final silicon oxide film on the surface of the staircase according to the topology designed in process (a), wherein the initial silicon nitride film is deposited by atomic layer deposition (ALD) using a silicon-containing precursor containing halogen, and the initial silicon nitride film is converted into the final silicon oxide film by oxidizing the initial silicon nitride film without further deposition of a film, wherein Si-N bonds in the initial silicon nitride film are converted into Si-O bonds, after the formation of the initial silicon nitride film, purging the reaction space before the oxidation of the initial silicon nitride film, and the oxidation of the initial silicon nitride film is plasma oxidation in a reaction space into which an oxidizing gas is introduced, the oxidizing gas being at least one gas selected from the group consisting of O2, O3, CO2, N2O and H2O, wherein the target portion pre-selected in process (a) is the target portion of the selective deposition, wherein process (b) comprises: (ci) depositing a silicon oxide film on the surface of the staircase on the substrate; (cii) placing the substrate between two electrodes in parallel with the two electrodes in a manner to anisotropically nitridate the surface of the silicon oxide film using a nitrogen-containing hydrogen plasma generated by applying RF power between the two electrodes mainly on the top and bottom surfaces of the staircase but not on the sidewalls of the staircase, thereby introducing -NH end groups on the surface of the silicon oxide film; (ciii) depositing at least a portion of the initial silicon nitride film on the surface-treated silicon oxide film by ALD using the precursor and a nitriding gas excited by plasma generated by applying RF power between the two electrodes and in contact with the silicon oxide film that has been anisotropically nitridated; (civ) oxidizing the at least a portion of the initial silicon nitride film using an excited oxidizing gas to obtain at least a portion of the final silicon oxide film without further deposition of a film, wherein Si-N bonds in the initial silicon nitride film are converted into Si-O bonds; and (cv) repeating processes (cii) and (civ) as needed until the final silicon oxide film having a desired thickness is obtained.

2. The method according to claim 1, wherein the precursor used in process (b) is carbon-free, and the final silicon oxide film is carbon-free.

3. The method according to claim 1, wherein the formation of the initial silicon nitride film and the oxidation of the initial silicon nitride film are performed consecutively in the same reaction space in process (b).

4. The method according to claim 1, wherein the initial silicon nitride film is composed of a plurality of monolayers, and in process (b), the oxidation of the initial silicon nitride film is performed after each monolayer deposition cycle of the ALD of the initial silicon nitride film or after each multiple of monolayer deposition cycles of the ALD of the initial silicon nitride film.

5. The method of claim 1, wherein the nitrogen-containing hydrogen plasma in process (cii) uses a mixture of N2and H2, NH3, other N x H y are generated, where x and y are integers, or a mixture of two or more of the foregoing is used.

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

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