Method of manufacturing a semiconductor device

Abstract

A substrate processing method with improved etching selectivity includes: a first operation for forming a film on a stepped structure having a top surface, a bottom surface, and side surfaces connecting the top surface and the bottom surface, wherein a first atmosphere is set to shorten the mean free path of plasma ions and make the plasma ions non-directional; and a second operation for changing the bonding structure of a part of the film, wherein a second atmosphere is set to make the plasma ions directional, wherein the first operation is repeated multiple times, the second operation is performed for a predetermined period of time, the first operation and the second operation form a set of cycles, and the set of cycles is repeated multiple times.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the benefit of U.S. Provisional Application No. 62 / 827,713, filed on Apr. 1, 2019, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] One or more embodiments relate to a method of manufacturing a semiconductor device, and more particularly, to a method of manufacturing a semiconductor device that can improve the etching selectivity of a film formed on a stepped structure. Background Art

[0004] In processes for manufacturing devices in which microcircuits are formed on a substrate, techniques are used for forming thin films on structures having steps. Specifically, high-density integrated circuits such as three-dimensional semiconductor devices include trench structures or stepped structures, and thin films need to be formed on selected regions of such structures. Summary of the Invention

[0005] The present disclosure provides a substrate processing method for forming a deposited film having high etching selectivity on a stepped structure with a high aspect ratio, and patterning the film by an isotropic etching process without performing a lithography process.

[0006] The present disclosure provides a substrate processing method capable of controlling the profile of a deposited film formed on a stepped structure.

[0007] Other aspects will be set forth in part in the description that follows and, in part, will be obvious from the description, or may be learned by practice of the presented embodiments.

[0008] According to an aspect of an embodiment based on the technical concept of the present disclosure, a substrate processing method includes: a first operation for forming a film on a stepped structure having a top surface, a bottom surface, and side surfaces connecting the top surface and the bottom surface, wherein a first atmosphere is set to shorten the mean free path of plasma ions and make the plasma ions non-directional; and a second operation for changing the bonding structure of a part of the film, wherein a second atmosphere is set to make the plasma ions directional, wherein the first operation is repeated multiple times, the second operation is performed for a predetermined period of time, the first operation and the second operation form a set of cycles, and the set of cycles is repeated multiple times.

[0009] According to an example of the substrate processing method, the substrate processing method may further include performing isotropic etching on the film formed by repeating the set of cycles multiple times.

[0010] According to another example of the substrate processing method, during isotropic etching, an etching selectivity can be achieved between a portion where the bonding structure of the deposited film has changed and another portion of the deposited film.

[0011] According to another example of the substrate processing method, in a set of cycles, the first operation can be performed m times, the second operation can be performed for n seconds, and the ratio of n to m can be adjusted to control the profile of the remaining film by isotropic etching.

[0012] According to another example of the substrate processing method, during the second operation, the bonding structure of the portion of the film can be weakened by the ion bombardment effect of plasma ions.

[0013] According to another example of the substrate processing method, the plasma ions can have a directionality perpendicular to the top surface and the bottom surface of the stepped structure, such that after isotropic etching, a portion of the film formed on the top surface and the bottom surface is removed, and a portion of the film on the side surface remains.

[0014] According to another example of the substrate processing method, the pressure of the first atmosphere can be higher than the pressure in the second atmosphere.

[0015] According to another example of the substrate processing method, the plasma power in the first atmosphere can be lower than the plasma power in the second atmosphere.

[0016] According to another example of the substrate processing method, the temperature of the first atmosphere can be higher than the temperature in the second atmosphere.

[0017] According to another example of the substrate processing method, the first operation can include: supplying a first gas; purging the first gas; and supplying a second gas and performing a first plasma treatment to form a film.

[0018] According to another example of the substrate processing method, the second operation can include performing a second plasma treatment on the film.

[0019] According to another aspect of an embodiment based on the technical concept of the present disclosure, a substrate processing method includes: supplying a first source gas; purging the first source gas; supplying a first reaction gas and performing a first plasma treatment to form a first film; supplying a second source gas onto the first film; purging the second source gas; supplying a second reaction gas and performing a second plasma treatment to form a second film on the first film; and performing a third plasma treatment on at least a portion of the first film and the second film, wherein the first film and the second film form a film including the same material.

[0020] According to an example of a substrate processing method, the substrate processing method may further include: supplying a third source gas onto a second deposited film; supplying a third reaction gas and performing a fourth plasma treatment to form a third film on the second film; and performing a fifth plasma treatment on the third film, wherein the first film, the second film, and the third film form films containing the same material.

[0021] According to another example of a substrate processing method, a film may be formed on a stepped structure having a top surface, a bottom surface, and side surfaces connecting the top surface and the bottom surface, and a bonding structure of a part of the film formed on the top surface and the bottom surface may be weakened by a third plasma treatment and a fifth plasma treatment.

[0022] According to another example of a substrate processing method, the first plasma treatment, the second plasma treatment, and the fourth plasma treatment may be performed at a first pressure, and the third plasma treatment and the fifth plasma treatment may be performed at a second pressure lower than the first pressure.

[0023] According to another example of a substrate processing method, a first power may be supplied during the first plasma treatment, the second plasma treatment, and the fourth plasma treatment, and a second power higher than the first power may be supplied during the third plasma treatment and the fifth plasma treatment.

[0024] According to another aspect of an embodiment based on the technical concept of the present disclosure, a substrate processing method includes: performing a set of cycles multiple times, wherein the set of cycles includes: a first operation for performing a first plasma treatment to form a film on a stepped structure having a top surface, a bottom surface, and side surfaces connecting the top surface and the bottom surface; and a second operation for performing a second plasma treatment on the film, wherein the first operation is performed multiple times during the set of cycles.

[0025] According to an example of a substrate processing method, during the first plasma treatment, the pressure of the reaction space may be maintained at a first pressure, and during the second plasma treatment, the pressure of the reaction space may be maintained at a second pressure lower than the first pressure.

[0026] According to another example of a substrate processing method, the power supplied during the first plasma treatment may be lower than the power supplied during the second plasma treatment.

[0027] According to another example of a substrate processing method, the substrate processing method may further include, after the set of cycles is performed multiple times, performing isotropic etching to remove a part of the film on the stepped structure to expose the surface of the stepped structure. Description of the Drawings

[0028] These and / or other aspects will become apparent and more readily appreciated from the following description of embodiments in conjunction with the accompanying drawings, in which:

[0029] Figure 1 is a flowchart schematically showing a substrate processing method according to an embodiment based on the technical concept of the present disclosure;

[0030] Figure 2 and 3 schematically shows a substrate processing method according to an embodiment based on the technical concept of the present disclosure;

[0031] Figure 4 schematically shows a substrate processing method according to an embodiment based on the technical concept of the present disclosure;

[0032] Figure 5 schematically shows a substrate processing method according to an embodiment based on the technical concept of the present disclosure;

[0033] Figure 6 shows features that can occur in the Figure 5 substrate processing method;

[0034] Figure 7 and 8 schematically shows a substrate processing method according to an embodiment based on the technical concept of the present disclosure;

[0035] Figure 9 shows the state after performing the substrate processing method according to the Figure 7 and Figure 8 embodiments;

[0036] Figure 10 shows the state after depositing a thin film and performing wet etching according to various conditions;

[0037] Figure 11 shows a state in which the profile of the thin film structure is controlled by changing conditions; and

[0038] Figure 12 schematically shows a substrate processing method according to an embodiment based on the technical concept of the present disclosure. DETAILED DESCRIPTION

[0039] Reference will now be made in detail to the embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. In this regard, the embodiments of the present invention may have different forms and should not be construed as limited to the description set forth herein. Accordingly, aspects of the present specification are illustrated only by describing the embodiments with reference to the drawings. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. When the expression "at least one of" is before an element, it modifies the entire list of elements and not individual elements of the list.

[0040] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0041] Embodiments of the present disclosure are provided to enable those of ordinary skill in the art to fully understand the present disclosure. However, the embodiments may be implemented in many different forms, and the scope of the present disclosure should not be construed as limited to the embodiments set forth herein. In fact, these embodiments are provided so that the present disclosure will be thorough and complete, and the concepts of the present disclosure will be fully conveyed to those of ordinary skill in the art.

[0042] The terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the present disclosure. As used herein, unless the context clearly dictates otherwise, the singular forms "a / an" and "the" are also intended to include the plural forms. It should be further understood that when used in this specification, the terms "comprises / comprising" specify the presence of the stated features, integers, steps, operations, elements, components, and / or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0043] It should be understood that although the terms "first", "second", etc. may be used herein to describe various components, regions, layers, parts, and / or elements, these components, regions, layers, parts, and / or elements should not be limited by these terms. These elements do not denote a particular order or superiority, but are only used to distinguish one component, region, layer, part, or element from another. Thus, a first component, region, part, or element may denote a second component, region, part, or element without departing from the teachings of the present disclosure.

[0044] In this specification, the term "gas" may include evaporated solids and / or liquids, and may be a single gas or a gas mixture. In this specification, the process gas introduced into the reaction chamber through the showerhead may include a precursor gas and an additive gas. The precursor gas and the additive gas may generally be introduced into the reaction space in the form of a mixed gas or may be independently introduced into the reaction space. The precursor gas may be introduced together with a carrier gas, such as an inert gas. The additive gas may include a reactive gas and a diluent gas, such as an inert gas. The reactive gas and the diluent gas may be mixed and introduced into the reaction space, or may be independently introduced into the reaction space. The precursor may include two or more precursors, and the reactive gas may include two or more reactive gases. The precursor is a gas that chemisorbs onto the substrate and generally contains metalloid or metal atoms that form the main structure of the dielectric film matrix, and the reactive gas for deposition is a gas that reacts with the precursor chemisorbed onto the substrate when the gas is excited to form an atomic layer or a monolayer onto the substrate. "Chemisorption" refers to chemical saturation adsorption. The gas other than the process gas, i.e., the gas introduced other than through the showerhead, may be used to seal the reaction space. The gas includes a sealing gas, such as an inert gas. According to some embodiments, a "film" refers to a layer that continuously extends in a direction perpendicular to the thickness direction without having pinholes so as to cover the entire area of the target or a partial surface related to the target, or a layer that only covers the target or a partial surface related to the target. In some embodiments, a "layer" refers to a structure having a certain thickness formed on a surface, a film-type layer, or a non-film structure. The film or layer may be a single discontinuous film or layer having certain characteristics, or may include multiple films or layers. The boundary between adjacent films or layers may be clear or unclear, and may be set based on physical characteristics, chemical characteristics, and / or other types of characteristics, the forming process or forming sequence, and / or the function or purpose of the adjacent films or layers.

[0045] In this specification, the feature of the phrase "containing Si—N bonds" may lie in one or more Si—N bonds, which may have a main framework substantially formed by one or more Si—N bonds, and / or substituents substantially formed by one or more Si—N bonds. The silicon nitride layer may be a dielectric layer containing Si—N bonds, and may include a silicon nitride layer (SiN) and a silicon oxynitride layer (SiON).

[0046] In this specification, the term "same material" shall be construed to include the same main components. For example, when the first layer and the second layer are both silicon nitride layers and are formed of the same material, the first layer may be selected from the group consisting of Si2N, SiN, Si3N4, and Si2N3 and the second layer may also be selected from the same group. However, specifically, the film material of the second layer may be different from that of the first layer.

[0047] In addition, in this specification, as can be determined based on routine operations according to the executable range, two parameters can constitute an executable range, and the specified range can include or exclude endpoints. Additionally, the values of some specified parameters (regardless of whether the value is specified by "about") can refer to exact values or approximate values, and can include their equivalents. According to some embodiments, the values of some specified parameters can refer to average values, central values, representative values, multiple values, etc.

[0048] In this specification, when conditions and / or structures are not specified, those of ordinary skill in the art can easily provide these conditions and / or structures as a matter of routine experimentation. In all disclosed embodiments, the components used in one embodiment include components that are explicitly, necessarily, or inherently disclosed herein for the intended purpose, and thus can be replaced by any one of the components equivalent to the said components. Furthermore, the present disclosure is equally applicable to apparatuses and methods.

[0049] Hereinafter, embodiments according to the technical concept of the present disclosure will be described with reference to the drawings. In the drawings, shape variations of the illustrations are expected as a result of, for example, manufacturing techniques and / or tolerances. Therefore, the embodiments of the present disclosure should not be construed as limited to the specific shapes of the regions shown herein, but include, for example, shape deviations caused by manufacturing.

[0050] Figure 1 is a flowchart schematically showing a substrate processing method according to an embodiment based on the technical concept of the present disclosure.

[0051] Referring to Figure 1 , a film can be formed in a first atmosphere in a first operation S110. The film can be formed on a stepped structure. That is, the film can be formed on a stepped structure having a top surface, a bottom surface, and side surfaces connecting the top surface and the bottom surface. The stepped structure can be a structure having a high aspect ratio, and the aspect ratio can be, for example, width:height = 1:10 or greater. To form a conformal deposition film on a stepped structure having a high aspect ratio, an atomic layer deposition (ALD) process can be used. More specifically, a plasma-enhanced atomic layer deposition (PEALD) process can be used.

[0052] The first atmosphere in which the deposition film is formed can be set such that the mean free path of plasma ions is shortened and the plasma ions do not have directionality (i.e., such that the random motion of plasma ions is increased). The first atmosphere can contribute to the formation of a conformal deposition film on a stepped structure having a high aspect ratio. To achieve the first atmosphere, a high-pressure (e.g., 10 Torr to 20 Torr) atmosphere can be generated. According to another embodiment, to achieve the first atmosphere, a low-power atmosphere (e.g., 200 W to 500 W) can be generated. According to still another embodiment, to achieve the first atmosphere, a high-temperature atmosphere can be generated.

[0053] The first operation S110 of forming a film on a stepped structure may include an operation of performing a first plasma treatment. More specifically, the first operation S110 may include an operation of supplying a first gas, an operation of purging the first gas, an operation of supplying a second gas, an operation of performing a first plasma treatment, and an operation of purging the second gas. When the first plasma treatment is performed, the second gas may be excited, and the reactive second gas may react with the first gas to form a film.

[0054] The first gas (which is a source gas) may include a material that chemisorbs on the substrate. The second gas may include a material that is reactive with the first gas, especially a material that is reactive with the first gas in a plasma atmosphere. According to an alternative embodiment, the operation of supplying the second gas and the operation of performing the first plasma treatment may be performed simultaneously.

[0055] The operation of forming a film on a stepped structure in a first atmosphere (i.e., the first operation S110) may be performed multiple times (e.g., M times). More specifically, a group cycle GC may be performed multiple times to deposit a film, and during each group cycle GC, the first operation S110 may be performed multiple times. The number of repetitions of the first operation S110 is related to a second atmosphere set in a subsequent second operation S120. In other words, the first operation S110 may be repeatedly performed a predetermined number of times (i.e., M times) to form a film having a thickness suitable for plasma treatment that will be performed in the second atmosphere.

[0056] After the first operation S110 is performed multiple times, a second operation S120 of changing the bonding structure of a part of the film may be performed. During the second operation S120, a second plasma treatment may be performed on the film to change the bonding structure of a part of the film. It should be noted that the second plasma treatment during the second operation S120 is different from the first plasma treatment that has been performed during the first operation S110. The second operation S120 may be performed in a second atmosphere, and the second atmosphere may be set so that plasma ions have directionality. In contrast, the first operation S110 may be performed in a first atmosphere, and the first atmosphere may be set so that plasma ions do not have directionality.

[0057] The directional plasma ions supplied during the second operation S120 can change the bonding structure of a part of the film. For example, when forming a film on a stepped structure with an aspect ratio, the directionality of the plasma ions can be set to face the top surface or the bottom surface of the stepped structure. In this case, the plasma ions can change the bonding structure of the film formed on the top surface or the bottom surface of the stepped structure. In contrast, the directional plasma ions can have a minimal impact on the bonding structure of the film formed on the side surface of the stepped structure.

[0058] The change in the bonding structure of the part of the film caused by the plasma ions can be a weakening of the bonding structure (see Figure 2 ) or a densification of the bonding structure (see Figure 3 ). Hereinafter, assuming a weakening of the bonding structure, embodiments of the present disclosure will be described in more detail.

[0059] During the second operation S120, the bonding structure of the part of the film can be weakened by the ion bombardment effect of the plasma ions. More specifically, the plasma ions can have a directionality perpendicular to the top surface and the bottom surface of the stepped structure. Therefore, the bonding structures of the top surface and the bottom surface of the film can be weakened. Thus, in the subsequent isotropic etching operation S140, the films formed on the top surface and the bottom surface of the stepped structure can be removed, and the film formed on the side surface of the stepped structure can be retained.

[0060] During the second operation S120, a gas having the same material as the second gas (e.g., a reaction gas) supplied in the first operation S110 can be supplied. The gas supply conditions in the second operation S120 can be different from the gas supply conditions in the first operation S110. For example, nitrogen can be supplied as a reaction gas during the first operation S110 and the second operation S120. In this case, the amount of nitrogen supplied in the second operation S120 can be less than the amount of nitrogen supplied in the first operation S110. In addition, the temperature of the nitrogen supplied in the second operation S120 can be lower than the temperature of the nitrogen supplied in the first operation S110. In addition, the plasma power applied to the nitrogen supplied in the second operation S120 can be lower than the plasma power of the nitrogen supplied in the first operation S110.

[0061] Under such supply conditions, as described above, in the first operation S110, the random movement of the reaction gas (e.g., nitrogen) can increase to form a film with a uniform quality in both the horizontal and vertical directions, while in the second operation S120, the directionality of the reaction gas (e.g., nitrogen) can increase to change the bonding structure of the film (i.e., the film formed on the top surface and the bottom surface of the stepped structure) in the vertical direction.

[0062] To increase the random movement of the reaction gas in the first operation S110, the pressure of the reaction space can be maintained at a first pressure (e.g., a high pressure) during the first plasma treatment. In contrast, to make the movement of the reaction gas directional in the second operation S120, the pressure of the reaction space can be maintained at a second pressure lower than the first pressure (e.g., a low pressure) during the second plasma treatment.

[0063] In addition, to make the reaction gas less affected by power in the first operation S110 (i.e., make the plasma ions non-directional), the power supplied during the first plasma treatment can be maintained at a first power value (e.g., a low power value). In contrast, to make the reaction gas more affected by power in the second operation S120 (i.e., make the plasma ions directional), the power supplied during the second plasma treatment can be maintained at a second power value higher than the first power value (e.g., a high power value).

[0064] In some alternative embodiments, to change the bonding structure of the deposited film during the second operation S120, a gas including hydrogen (e.g., hydrogen-containing nitrogen gas) can be supplied into the reaction space. By performing plasma treatment using the gas including hydrogen, more Si-H bonds can be formed in the film formed on the top surface and the bottom surface of the stepped structure, and thus, during subsequent etching processing, the wet etching rate (WER) can be increased at the corresponding portions of the film.

[0065] The first operation S110 performed multiple times in the first atmosphere and the second operation S120 performed for a predetermined period (e.g., N seconds) in the second atmosphere can be defined as a group cycle GC, and the group cycle GC can be repeatedly executed. In other words, before executing the group cycle GC, the X value can be set to 1 in the operation S100, and when executing the group cycle GC including the first operation S110 and the second operation S120, the X value can be increased in the operation S150. When the X value reaches a predetermined value in the operation S130, the group cycle GC can be terminated, and the subsequent isotropic etching operation S140 can be executed.

[0066] Thereafter, an isotropic etching operation S140 can be performed on the film formed by executing the group cycle GC multiple times. For example, wet etching can be performed on the film. For example, wet etching can be performed by dipping a semiconductor device (i.e., a substrate having a thin film thereon) into a liquid etching solution to etch the substrate surface. Since wet etching is isotropic etching, the isotropic etching may not greatly affect the selective etching of the film formed on the stepped structure.

[0067] During the isotropic etching operation S140, an etching selectivity can be achieved between the portion of the film where the bonding structure has changed and other portions of the film. In other words, by performing the second operation S120 of applying plasma to the film after the first operation S110 of forming the film on the stepped structure, the bonding structure of some portions of the film on the stepped structure can be changed, and thus, during the isotropic etching, some portions of the film can be removed and other portions of the film can be retained. Since some portions of the film on the stepped structure are removed, the corresponding surfaces of the stepped structure can be exposed. Therefore, selective etching of the deposited film can be achieved by a subsequent etching process. Thus, a patterned film can be formed on the area of the stepped structure without performing an additional lithography process.

[0068] According to an alternative embodiment, in the group cycle GC, the first operation S110 can be performed M times, the second operation S120 can be performed for N seconds, and the ratio of M to N can be adjusted to control the profile of the remaining deposited film by isotropic etching. For example, by increasing the value of N relative to the value of M, the etching selectivity between the film formed on the top surface and the bottom surface of the stepped structure and the film formed on the side surface of the stepped structure can be increased. By adjusting the etching selectivity, the degree of exposure of the bottom surface of the stepped structure can be adjusted (see Figure 10 ). That is, by adjusting the values of M and N, the profile of the deposited film remaining on the bottom surface of the stepped structure can be finely adjusted.

[0069] Therefore, according to an embodiment based on the technical concept of the present disclosure, the first operation and the second operation can form a group cycle, and the group cycle can be performed multiple times, rather than performing the first operation of forming a film with a thickness of a nanometers on the stepped structure and the second operation of performing plasma treatment on the film for b seconds once. In other words, the first operation of forming a film with a thickness of c nanometers (c < a) on the stepped structure and the second operation of performing plasma treatment on the film for d seconds (d < b) can be performed x times (x > 1). Therefore, the etching selectivity between the film formed on the top surface and the bottom surface of the stepped structure and the film formed on the side surface of the stepped structure can be improved.

[0070] Figure 2 and Figure 3 Schematically shows a substrate processing method according to an embodiment based on the technical concept of the present disclosure. The substrate processing method according to the embodiment can be a modified example of the substrate processing method according to the above embodiment. Hereinafter, redundant descriptions of the embodiment will be omitted.

[0071] Reference Figure 2, during the second operation S120 of performing plasma treatment on the deposited film, the bonding structure of the film can be weakened by plasma ions having directionality in the second atmosphere. For example, by using conditions of low pressure and high plasma power, the bonding structure of the film formed on the top surface and the bottom surface of the stepped structure can be weakened by the ion bombardment effect of active species. According to another example, hydrogen active species can be generated from the gas present in the reaction space due to the reaction conditions of the second atmosphere, and the hydrogen active species can have directionality to collide with the film formed on the top surface and the bottom surface of the stepped structure, so that the bonding structure of the corresponding part of the deposited film can be weakened.

[0072] Therefore, during the subsequent isotropic etching operation S140, the weakened part of the film (e.g., the film formed on the top surface and the bottom surface of the stepped structure) can be removed, and other parts can be retained, thereby achieving selective etching. According to some embodiments, in order to perform selective etching more stably, a film having a first bonding structure (e.g., a strong bonding structure) can be formed during the first operation S110.

[0073] Compared with Figure 2 the embodiment of, during the second operation S120 of performing plasma treatment on the film, as Figure 3 shown in, the bonding structure of the film can be densified by plasma ions having directionality in the second atmosphere. For example, plasma ions having the components of the film can be provided to the film formed on the top surface and the bottom surface of the stepped structure. As a specific example, when the film is a thin film having Si—N bonds, nitrogen ions can be provided to the top surface and the bottom surface of the stepped structure, and thus, more Si—N bonds can be generated, so that the bonding structure of the film can be densified.

[0074] Therefore, during the subsequent isotropic etching operation S140, the densified part of the film (e.g., the film formed on the top surface and the bottom surface of the stepped structure) can be retained, and other parts can be removed, thereby achieving selective etching. According to some embodiments, in order to perform selective etching more stably, a film having a second bonding structure (e.g., a weak bonding structure) can be formed during the first operation S110.

[0075] Figure 4 Schematically shows a substrate processing method according to an embodiment based on the technical concept of the present disclosure. The substrate processing method according to the embodiment can be a modified example of the substrate processing method according to the above embodiment. Hereinafter, redundant descriptions of the embodiment will be omitted.

[0076] Refer to Figure 4, in operation S100, X representing the number of times of the group cycle GC can be set to an initial value of 1, and in operation S10, M representing the number of times of execution of the first operation S110 for forming a film can also be set to an initial value of 1. Subsequently, the first operation S110 executed for the Mth time in the Xth group cycle can be performed. During the execution of the first operation for the Mth time (M = 1), the first source gas can be first supplied to the reaction space in operation S11. In operation S12, the first source gas can be chemisorbed on the surface of the pattern structure (e.g., a stepped structure with a high aspect ratio (10:1 or greater)), and the remaining first source gas in the reaction space can be purged and removed from the reaction space. Thereafter, the first reaction gas can be supplied to the reaction space. After (or, when) the first reaction gas is supplied, in operation S13, the first plasma treatment can be performed to form the first film. Subsequently, in operation S14, the remaining reaction gas in the reaction space can be purged and removed from the reaction space.

[0077] Thereafter, M can be increased (i.e., M = 2), and then the first operation S110 executed for the Mth time can be performed. That is, in operation S11', the second source gas can be supplied to the reaction space, and in operation S12', the remaining second source gas in the reaction space can be purged and removed from the reaction space. Thereafter, the second reaction gas can be supplied to the reaction space, and in operation S13', the second plasma treatment can be performed to form the second film. Subsequently, in operation S14', the remaining second reaction gas in the reaction space can be purged and removed from the reaction space.

[0078] Therefore, the first operation S110 can be repeated multiple times. The first operation S110 can be repeatedly executed until M reaches a predetermined value. When the first operation S110 is repeatedly executed, the value of M can continuously increase. The multiple films formed by executing the first operation S110 multiple times can form films including the same material.

[0079] After a film with a desired thickness is formed by executing the first operation S110 a predetermined number of times, the second operation S120 can be performed. During the second operation S120, the third plasma treatment can be performed on the formed film. As described above, the first atmosphere of the reaction space where the first operation S110 is performed can be different from the second atmosphere of the reaction space where the second operation S120 is performed.

[0080] Through the third plasma treatment, the bonding structure of the film formed by the first operation S110 can be changed (e.g., weakened). Thereafter, the group cycle GC including the first operation S110 and the second operation S120 can be repeatedly executed. That is, the X value can be increased from 1 to 2, the first operation S110' can be executed M times again, and then the second operation S120' can be executed again.

[0081] For example, the second group cycle GC executed after the X value is increased from 1 to 2 may further include an operation S11” of supplying a third source gas to the second film, an operation S12” of purging the third source gas, an operation S13” of supplying a third reaction gas and performing a fourth plasma treatment to form a third film on the second film, an operation S14” of purging the third reaction gas, and an operation S120' of performing a fifth plasma treatment on the third film.

[0082] The first film and the second film formed during the first operation S110 of the first group cycle GC, and the third film formed during the first operation S110' of the second group cycle GC can form films including the same material. The first operation can continue to be executed to form a fourth deposited film. In another alternative embodiment, for each group cycle, the number of executions of the first operation during the group cycle can be different.

[0083] After forming the third film and / or the fourth film, a fifth plasma treatment can be performed. Through the fifth plasma treatment, the bonding structure of the third film and / or the fourth film can be changed. In other words, through the third plasma treatment (operation S120) of the first group cycle and the fifth plasma treatment (operation S120') of the second group cycle, the bonding structure of a part of the deposited film can be changed.

[0084] For example, when forming a silicon nitride film on a top surface, a bottom surface, and a side surface connecting the top surface and the bottom surface, high-power plasma ions can be implanted into the film. Then, the Si—N bonding structure of the silicon nitride film can be broken. Because the plasma ions have a directionality (vertical directionality from a shower head positioned above to a susceptor positioned below), the bonding structure of the film formed on the top surface and the bottom surface of the stepped structure can be weakened.

[0085] According to an embodiment based on the technical concept of the present disclosure, when forming a film of a predetermined thickness, a part of the film may be formed in some of a plurality of grouped cycles, and the remaining part of the film may be formed in the remaining grouped cycles. In addition, plasma treatment may be performed on a part of the film during each grouped cycle. Therefore, by repeatedly performing the grouped cycles for forming a part of the film and performing plasma treatment on the part of the film, instead of depositing a film of a predetermined thickness and performing plasma treatment on the entire deposited film, the etching selectivity between the film formed on the top surface and the bottom surface of the stepped structure and the film formed on the side surface of the stepped structure can be improved.

[0086] According to some embodiments, during the first plasma treatment (operation S13) and the second plasma treatment (operation S13') of the first grouped cycle for forming a conformal deposition film and the fourth plasma treatment (operation S13'') of the second grouped cycle, the first atmosphere in the reaction space may be set so that the plasma ions do not have directivity. For example, the first plasma treatment (operation S13), the second plasma treatment (operation S13'), and the fourth plasma treatment (operation S13'') may be performed at a first pressure (i.e., a high pressure of, for example, 10 Torr to 20 Torr). As another example, during the first plasma treatment (operation S13), the second plasma treatment (operation S13'), and the fourth plasma treatment (operation S13''), a first power (i.e., a low power of, for example, 200 W to 500 W) may be supplied.

[0087] In contrast, during the third plasma treatment (operation S120) of the first grouped cycle and the fifth plasma treatment (operation S120') of the second grouped cycle, the second atmosphere in the reaction space may be set so that the plasma ions have directivity. For example, the third plasma treatment (operation S120) and the fifth plasma treatment (operation S120') may be performed at a second pressure lower than the first pressure (i.e., a low pressure of, for example, 1 Torr to 5 Torr). As another example, during the third plasma treatment (operation S120) and the fifth plasma treatment (operation S120'), a second power higher than the first power (i.e., a high power of, for example, 700 W to 1000 W) may be supplied.

[0088] Figure 5 Schematically shows a substrate processing method according to an embodiment based on the technical concept of the present disclosure.

[0089] Reference Figure 5, the substrate processing method may include performing a first operation multiple times. In the first operation, a source gas (e.g., a silicon source) may be supplied for a duration from t0 to t1, the remaining source gas may be purged for a duration from t1 to t3, a reactive gas that is supplied to act as both a purge gas and a reaction gas may be excited by plasma to react with the source gas to form a film for a duration from t3 to t7, and the remaining reaction gas may be purged for a duration from t7 to t8. The first operation may be repeatedly performed such that a film of a predetermined thickness may be formed on a stepped structure.

[0090] For example, in order to deposit a SiN film on a stepped structure of a substrate, a silicon-containing precursor and N2 gas may be supplied, and when plasma is supplied, the N2 gas may be ionized to react with the silicon-containing precursor to form a thin film. Although the N2 gas continues to be supplied, the N2 gas may be ionized under plasma to act as a reactive purge gas that reacts with the source gas.

[0091] In the first operation, the process pressure may be maintained at 3 Torr or less, and the power value may be maintained at 900 W or higher such that a conformal deposition film is formed and, at the same time, a part of the film formed on the stepped structure is weakened. However, the process conditions may cause incomplete etching when performing subsequent isotropic etching on the film formed on the stepped structure (see Figure 6 ).

[0092] Figure 6 (a) of Figure 6 shows an example in which a part of the film (e.g., SiN film) is lost in a side portion of a step. Figure 6 (b) of Figure 6 shows an example in which a part of the film (e.g., SiN film) is lost in a side portion of a stepped structure having a large aspect ratio (e.g., an aspect ratio > 10:1), and the film (e.g., SiN film) remains in the bottom portion of the step.

[0093] According to an embodiment of the technical concept based on the present disclosure for preventing incomplete selective etching, a first operation of uniformly depositing a strong and uniform film on a stepped structure may be performed, and a second operation of performing plasma treatment to improve the etching selectivity of the film deposited on the side and top / bottom portions of the step may be performed.

[0094] Figure 7 and Figure 8Schematically shows a substrate processing method according to an embodiment based on the technical concept of the present disclosure. The substrate processing method according to the embodiment may be a modified example of the substrate processing method according to the above embodiment. Hereinafter, redundant descriptions of the embodiment will be omitted.

[0095] Embodiments based on the technical concept of the present disclosure propose a method for preventing loss of a film deposited on a side portion of a step. More specifically, a method for increasing the strength and chemical resistance of the film to improve the etching selectivity between the film deposited on the top / bottom portion of the step and the film deposited on the side portion of the step can be proposed to prevent the film deposited on the side portion of the step from being easily lost.

[0096] Referring Figure 7 and Figure 8 , in a first operation (t0 to t8), a film can be deposited by a PEALD process, and the first operation is an operation of uniformly depositing a hard and uniform film (e.g., a SiN film) on a stepped structure. The first operation can be repeatedly performed m times. A second operation (t8 to t15) can be repeatedly performed for n seconds, and the second operation is a plasma treatment operation. The set of cyclic operations composed of the first operation and the second operation can be repeatedly performed multiple times (e.g., x cycles).

[0097] In the first operation, a hard and conformal film (e.g., a SiN film) can be deposited on the stepped structure under conditions of high pressure (e.g., 15 Torr) and relatively low plasma power (e.g., 500 W). Since there is a large amount of gas (i.e., high pressure) in the reaction space and the plasma is relatively weak (i.e., low power), the mean free path of radical ions can be shortened, and the random movement of radical ions can be increased. Therefore, ions can be uniformly distributed on the top / bottom and side portions of the stepped structure, so that the reaction between the substrate surface and ionic radicals occurs uniformly over the entire surface without bias towards a certain surface of the step, and thus a hard and uniform film (conformal film) can be deposited.

[0098] In the second operation, plasma can be supplied for a predetermined period of time under conditions of relatively lower pressure and relatively higher plasma power compared to those in the first operation to increase the ion bombardment effect of plasma ions. For example, in the second operation, the process pressure can be 3 Torr and the plasma can be about 900 W. To maintain the internal pressure of the chamber at a low pressure, the amount of reaction gas can be reduced if necessary. Since, different from the first operation, the directionality (linearity) of radical ions is enhanced, the bonding structure of a film (e.g., SiN film) deposited on a certain surface of a step perpendicular to the traveling direction of the radicals (e.g., on the top / bottom part of the step) can be weakened by ion bombardment. The first operation and the second operation can form a set of cycles, and the set of cycles can be repeatedly executed x times to deposit a desired film thickness. Thereafter, isotropic etching (e.g., wet etching) can be performed to remove the film formed on the top / bottom surface of the stepped structure while maintaining the film formed on the sidewalls.

[0099] The following table details the process conditions according to an embodiment based on the technical concept of the present disclosure.

[0100]

[0101] In the above table, comparing the first operation with the second operation, a relatively large amount of gas can be supplied at a ratio of 5:1 to a maximum of 20:1 in the first operation. By setting the supply time of the plasma to 1:1 to a maximum of 1:60, the plasma power to 1:3.5 to a maximum of 1:5, and the process pressure to 2:1 to a maximum of 20:1, the first operation can shorten the mean free path of radical ions to deposit a uniform and hard film on the stepped structure, and the second operation can improve the linearity and ion bombardment effect of radical ions to weaken the bonding structure of the film deposited on the top / bottom surface of the stepped structure. Therefore, the film deposited on the side part of the step in the first operation can be hardened, thereby preventing loss during subsequent etching operations.

[0102] Figure 9 The results after performing a substrate processing method according to an embodiment of Figure 7 and Figure 8 are shown by depositing an SiN film on the stepped structure according to the process conditions shown in the above table and performing subsequent etching processes.

[0103] As Figure 9 shown, the SiN film on the sidewalls of the step is maintained at a constant thickness without loss even at the boundary between the sidewall and the bottom wall of the step, while the SiN film on the bottom surface of the step is selectively removed.

[0104] In addition, according to an embodiment based on the technical concept of the present disclosure, by changing the film materials of the films formed on the top portion and the bottom portion of the step while maintaining the film materials of the films on the side portion of the step, various forms of RTS (reverse topo-selective) process windows can be ensured. More specifically, by adjusting the plasma processing conditions of the second operation, the wet etching selectivity between the top / bottom portion of the step and the side portion of the step can be arbitrarily adjusted, and the film profile after etching can be adjusted.

[0105] As an example related to the selective adjustment, the following table shows the etching selectivity of the top surface and the side surface of the step according to the number of repetitions of the first operation and the number of plasma treatments of the second operation. When the number of repetitions of the first operation is m (times) and the processing time of the second operation is n (seconds), the subsequent wet etching rates according to the changes of m and n are as follows.

[0106]

[0107]

[0108] In the above table, the conformal deposition condition represents the case where the first operation is performed without the second operation. The treatment 1 condition (TRT1) represents the case where the first operation is performed 40 times (40 cycles) and the second operation is performed for 1 minute (60 seconds). The treatment 2 condition (TRT2) represents the case where the first operation is performed 20 times (20 cycles) and the second operation is performed for 1 minute (60 seconds).

[0109] As shown in the above table, as the ratio of the second operation to the first operation increases, the selectivity between the top portion and the side portion in the stepped structure increases. That is, the above table shows that the highest WER selectivity of 25.8 is obtained under the treatment 2 condition. In other words, compared with the conformal deposition condition, the SiN film on the top portion of the step is etched rapidly, while the SiN film on the side portion of the step is hardly etched under the treatment 2 condition (TRT2). Therefore, a higher etching selectivity can be achieved.

[0110] Figure 10 The SiN film on the step is shown after wet etching is performed according to the conditions of the said table (i.e., the conformal deposition condition, the treatment 1 condition, and the treatment 2 condition).

[0111] Reference Figure 10, the conformal deposition condition represents the case where the first operation is applied without the second operation to deposit a conformal SiN film in a stepped structure. Under the conformal deposition condition, a high process pressure and a low plasma power can be applied. Thus, the radical ions can be uniformly distributed over the whole of the stepped structure, and even after wet etching, a hard SiN film with a constant thickness can be uniformly retained on the top, side, and bottom portions of the step (see Figure 10 the left portion).

[0112] Subsequently, in the process 1 condition (TRT1), the first operation can be performed for 40 cycles, and then the plasma treatment of the second operation can be performed for 1 minute. As shown in the middle portion of Figure 10 , the SiN film formed on the side portion remains as it is, and the SiN film formed on the bottom portion is partially removed. However, in the bottom portion of the stepped structure, the SiN film may still remain.

[0113] Finally, under the process 2 condition (TRT 2), the first operation can be performed for 20 cycles, and then the plasma treatment of the second operation can be performed for 1 minute. That is, by increasing the ratio of the second operation to the first operation, the SiN film formed on the side of the step is maintained at its initial thickness without loss, and after etching, the SiN film formed on the bottom portion of the step is removed (see Figure 10 the right portion). Therefore, by appropriately adjusting the ratio of the first operation to the second operation, a substrate processing process with an improved thickness adjustment function can be implemented.

[0114] Figure 11 shows the process.

[0115] As shown in Figure 11 , by increasing the ratio of the second operation to the first operation, the profile of the SiN film can be adjusted. For example, when the second operation is not performed ( Figure 11 the left portion), even after isotropic etching, the SiN film formed on the bottom surface of the pattern PTN remains as it is. Meanwhile, when the second operation is performed at a relatively low frequency ( Figure 11 the middle portion), after isotropic etching, the SiN film formed on the bottom surface of the pattern PTN is partially removed, exposing a part of the bottom surface of the pattern PTN. In addition, when the second operation is performed at a relatively high frequency ( Figure 11 the right portion), after isotropic etching, the SiN film formed on the bottom surface of the pattern PTN is completely removed, exposing the entire bottom surface of the pattern PTN.

[0116] Therefore, the profile of the SiN film formed on the bottom portion and the side portion of the step can be controlled according to the number of times of the plasma processing operation. Therefore, various shapes of the thin film profile can be implemented according to the application target. For the wiring of the top / bottom portion in the device, the bottom film formed on the step can be removed. In addition, by opening a part of the bottom film, a device with more improved performance can be manufactured.

[0117] Figure 12 Schematically shows a substrate processing method according to an embodiment based on the technical concept of the present disclosure. The substrate processing method according to the embodiment can be a modified example of the substrate processing method according to the above embodiment. Hereinafter, redundant descriptions of the embodiment will be omitted.

[0118] Reference Figure 12 , an embodiment based on the technical concept of the present disclosure proposes a substrate processing method for processing a substrate by performing a plurality of grouped cycles, and the substrate processing method can selectively etch a thin film on a pattern PTN by isotropic etching (e.g., wet etching) without performing an additional lithography process.

[0119] The grouped cycle can include a plurality of deposition cycles and plasma processing, and when performing a plurality of deposition cycles, a conformal deposition film having a low subsequent wet etching rate WER can be formed on the stepped structure. By performing a strong plasma process on the film formed after a plurality of deposition cycles, the bonding structure of a part of the film formed on the top and bottom portions of the stepped structure can be changed. The change in the bonding structure can cause an increase in the subsequent wet etching rate WER.

[0120] After the grouped cycle is terminated by performing a plurality of deposition cycles and strong plasma processing, the next grouped cycle can be performed so that the plurality of deposition cycles and the strong plasma processing are repeated again. Therefore, a plurality of grouped cycles can be performed to form a film having a predetermined thickness by forming a film in each grouped cycle and performing plasma processing on a part of the film, thereby forming a film with improved etching selectivity. Therefore, a patterned film can be formed on a stepped structure with a high aspect ratio without performing a lithography process.

[0121] It should be understood that the embodiments described herein should be considered as merely descriptive and not for the purpose of limitation. The description of the features or aspects in each embodiment should generally be considered as applicable to other similar features or aspects in other embodiments.

[0122] Although one or more embodiments have been described with reference to the drawings, those of ordinary skill in the art should understand that various changes in form and detail can be made therein without departing from the spirit and scope of the present disclosure defined by the appended claims.

Claims

1. A substrate processing method, comprising: A first operation for forming a film on a stepped structure having a top surface, a bottom surface, and side surfaces connecting the top surface and the bottom surface, wherein a first atmosphere is set to shorten the mean free path of plasma ions and to make the plasma ions non-directional; and a second operation for changing the bonding structure of a part of the film, wherein a second atmosphere is set such that the plasma ions have a directionality; wherein the first operation is repeated multiple times, the second operation is performed for a predetermined period of time, the first operation and the second operation form a set of cycles, and the set of cycles is repeated multiple times, wherein the method further includes performing isotropic etching on the film formed by performing the set of cycles multiple times; and wherein in the set of cycles, the first operation is performed m times and the second operation is performed for n seconds, and the ratio of n to m is adjusted to control the profile of the remaining film by the isotropic etching, during the first operation and the second operation, nitrogen is supplied as a reaction gas, and the amount of nitrogen supplied in the second operation is less than the amount of nitrogen supplied in the first operation, the temperature of the first atmosphere is higher than the temperature of the second atmosphere.

2. The substrate processing method according to claim 1, wherein, during the isotropic etching, an etching selectivity is achieved between the part of the film whose bonding structure has been changed and the other remaining part of the film.

3. The substrate processing method according to claim 1, wherein, during the second operation, the bonding structure of the part of the film is weakened by the ion bombardment effect of the plasma ions.

4. The substrate processing method according to claim 3, wherein the plasma ions have a directionality perpendicular to the top surface and the bottom surface of the stepped structure, such that after the isotropic etching, a part of the film formed on the top and bottom surfaces of the stepped structure is removed, and a part of the film formed on the side surface of the stepped structure remains.

5. The substrate processing method according to claim 1, wherein the pressure of the first atmosphere is higher than the pressure of the second atmosphere.

6. The substrate processing method according to claim 1, wherein the plasma power in the first atmosphere is lower than the plasma power in the second atmosphere.

7. The substrate processing method according to claim 1, wherein the first operation includes: supplying a first gas; purging the first gas; and supplying a second gas and performing a first plasma treatment to form the film.

8. The substrate processing method according to claim 7, wherein the second operation includes performing a second plasma treatment on the film.

9. A substrate processing method, comprising: performing a set of cycles multiple times to form a film; and performing isotropic etching on the film, wherein the set of cycles includes: a first operation for performing a first plasma treatment to form a film on a stepped structure, the stepped structure having a top surface, a bottom surface, and a side surface connecting the top surface and the bottom surface; and a second operation for performing a second plasma treatment on the film, Among them, during the set of cycles, the first operation is performed m times and the second operation is performed for n seconds, and the ratio of n to m is adjusted to control the profile of the remaining film by the isotropic etching, the first operation is performed multiple times, During the first operation and the second operation, nitrogen is supplied as a reaction gas, and the amount of nitrogen supplied in the second operation is less than the amount of nitrogen supplied in the first operation. The temperature of the first atmosphere is higher than the temperature of the second atmosphere.

10. The substrate processing method according to claim 9, wherein during the first plasma treatment, the pressure in the reaction space is maintained at a first pressure, and during the second plasma treatment, the pressure in the reaction space is maintained at a second pressure lower than the first pressure.

11. The substrate processing method according to claim 9, wherein the power supplied during the first plasma treatment is lower than the power supplied during the second plasma treatment.

12. The substrate processing method according to claim 9, further comprising, after performing the set of cycles multiple times, performing isotropic etching to remove a portion of the film on the stepped structure, thereby exposing the surface of the stepped structure.

Images