Substrate treatment methods

Abstract

A substrate processing method capable of achieving uniform etch selectivity across the entire thickness range of a thin film formed on a stepped structure, the method comprising: forming a thin film on a substrate by performing multiple cycles, the cycle comprising forming at least one layer and applying plasma to the at least one layer under a first processing condition; and applying plasma to the thin film under a second processing condition different from the first processing condition.

Description

Technical Field

[0001] One or more embodiments relate to a substrate processing method, and more specifically, to a substrate processing method that can improve the etch selectivity of thin films formed on stepped structures. Background Technology

[0002] As semiconductor patterned structures become miniaturized and three-dimensional, there is an increasing need for novel thin-film deposition techniques that can simplify processes. For example, 3D NAND flash memory devices have vertically stacked gate structures and electrode wiring structures. To interconnect these structures, techniques are needed to selectively remove the film deposited on the stepped structure to form pad structures.

[0003] To selectively remove the film deposited on the stepped structure, the film is deposited on the stepped structure using a plasma process, and then wet etched to remove the side films of the stepped structure, leaving the upper and lower films of the stepped structure. However, a method can also be used to remove the upper and lower films of the stepped structure while leaving the side films of the stepped structure.

[0004] This method can be achieved by controlling the plasma to be applied and adjusting the properties of the upper and lower films or side films of the stepped structure. For example, the side films can be removed during etching by utilizing the linearity of free radicals to make the upper and lower films harder than the side films in the direction perpendicular to the direction of free radical travel. Conversely, by increasing the intensity of the plasma to enhance ion bombardment, the bonding structure of the upper and lower films, rather than the side films, can be weakened, thereby removing the upper and lower films during etching.

[0005] This process can be accomplished by altering the plasma application conditions. For example, below a certain plasma power or density, film densification may dominate on the film surface perpendicular to the direction of radical propagation. Conversely, above a certain plasma power or density, the film bonding structure may be weakened on the film surface perpendicular to the direction of radical propagation. Summary of the Invention

[0006] One or more embodiments include a substrate processing method that improves the etch selectivity of a thin film by achieving uniform etch selectivity across the entire thickness of the film formed on the stepped structure.

[0007] Other aspects will be set forth in part in the description which follows, and will be apparent in part from the description, or may be learned by practicing the embodiments presented in this disclosure.

[0008] According to one or more embodiments, a substrate processing method includes: forming a thin film on a substrate by performing a plurality of cycles, the cycles including forming at least one layer and applying plasma to the at least one layer under a first processing condition for the layer; and applying plasma to the thin film under a second processing condition different from the first processing condition.

[0009] According to an example of a substrate treatment method, an atmosphere can be set such that the plasma ions are directional during the application of plasma under a first treatment condition and during the application of plasma under a second treatment condition.

[0010] According to another example of the substrate processing method, the bonding structure of a portion of the thin film can be altered during plasma application under the first processing conditions, and the bonding structure of a portion of the thin film can be further altered during plasma application under the second processing conditions.

[0011] According to another example of the substrate processing method, the substrate processing method further includes an isotropic etching operation, wherein during the isotropic etching operation, etching selectivity is achieved between the portion of the thin film whose bonding structure has been altered and the rest of the thin film.

[0012] According to another example of the substrate processing method, at least one layer may be formed on a stepped structure having an upper surface, a lower surface, and a side surface between the upper and lower surfaces, and the portion of the film corresponds to a portion of the film formed on the upper and lower surfaces.

[0013] According to another example of the substrate processing method, the repetition of the above-mentioned cycle results in a difference between the first bonding structure of the first portion of the film adjacent to the stepped structure and the second bonding structure of the second portion of the film away from the stepped structure, and the difference between the first bonding structure of the first portion and the second bonding structure of the second portion can be reduced during the application of plasma under the second processing conditions.

[0014] According to another example of the substrate processing method, the substrate processing method may also include an isotropic etching operation. After the isotropic etching operation, the film on the upper and lower surfaces of the stepped structure can be removed, while the film on the side surfaces of the stepped structure can be retained.

[0015] According to another example of the substrate treatment method, hydrogen-containing gas can be supplied during plasma application under the second treatment conditions.

[0016] According to another example of the substrate processing method, forming at least one layer may include: supplying a first gas; purging the first gas; and supplying a second gas and applying plasma to form the first layer.

[0017] According to another example of the substrate processing method, during the supply of the second gas and the application of plasma to form the first layer, the pressure in the reaction space is maintained at a first pressure, and during the application of plasma under the first processing conditions, the pressure in the reaction space can be maintained at a second pressure lower than the first pressure.

[0018] According to another example of the substrate processing method, the power supplied during the application of plasma under the first processing conditions is greater than the power supplied during the supply of the second gas and the application of plasma to form the first layer.

[0019] According to another example of the substrate treatment method, the first gas can be supplied during plasma application under a second treatment condition that is different from the first treatment condition.

[0020] According to another example of the substrate processing method, during the first cycle, the supply of a first gas, the purging of the first gas, and the supply of a second gas and the application of plasma to form a second layer can be performed multiple times.

[0021] According to another example of the substrate treatment method, during the first cycle, plasma under the first treatment conditions is applied to the first layer, such that the WER of a portion of the first layer can be increased due to the ion bombardment effect of plasma ions.

[0022] According to another example of the substrate processing method, during a second cycle following the first cycle, a second layer is formed on the first layer, wherein forming the second layer may include: supplying a first gas; purging the first gas; and supplying a second gas and applying plasma to form the second layer.

[0023] According to another example of the substrate treatment method, during the second cycle, plasma under the first treatment conditions is applied to the second layer and the first layer below the second layer, such that the WER of a portion of the first layer and a portion of the second layer can be increased due to the ion bombardment effect of plasma ions, wherein the WER of the first layer can be greater than the WER of the second layer.

[0024] According to another example of the substrate treatment method, plasma with a second treatment condition is applied to the first and second layers, thereby reducing the difference in WER between the first and second layers.

[0025] According to one or more embodiments, a substrate processing method includes: forming a first layer; applying a first plasma to the first layer to modify the properties of a portion of the first layer; forming a second layer on the first layer; applying a second plasma to the first layer and the second layer to modify the properties of corresponding portions of the first layer and the second layer; and applying a third plasma to the second layer to reduce the difference between the properties of the portion of the first layer and the properties of the portion of the second layer.

[0026] According to an example of a substrate processing method, a first processing condition may be used during the application of a first plasma and a second plasma, and a second processing condition different from the first processing condition may be used during the application of a third plasma.

[0027] According to one or more embodiments, a substrate processing method includes: forming a thin film on a substrate by repeatedly performing a cycle including supplying a first gas to a substrate and supplying a second gas that is reactive with the first gas, wherein, due to the repetition of the cycle, the WER of a first portion of the thin film adjacent to the substrate is higher than the WER of a second portion of the thin film distant from the substrate; and reducing the difference between the WER of the first portion and the WER of the second portion. Attached Figure Description

[0028] The above and other aspects, features, and advantages of specific embodiments of the present disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings, wherein:

[0029] Figure 1 This is a flowchart of the substrate processing method according to an embodiment;

[0030] Figure 2 This is a diagram of the substrate processing method according to an embodiment;

[0031] Figure 3 This is a diagram of the substrate processing method according to an embodiment;

[0032] Figure 4 This is a diagram of a substrate processing apparatus for performing a substrate processing method;

[0033] Figure 5 This is a view of the thin film formed on the stepped structure and the film retained after isotropic etching;

[0034] Figure 6 This is a diagram of the substrate processing method according to an embodiment;

[0035] Figure 7 This is a graph showing the variation in wet etching rate of the thin film;

[0036] Figure 8 This is a diagram showing the state of the thin film retained on the stepped structure after isotropic etching;

[0037] Figure 9 This is a diagram of the substrate processing method according to an embodiment;

[0038] Figure 10 This is a diagram showing the etching characteristics of the thin film after processing according to this disclosure;

[0039] Figure 11 This is a view of the etching selectivity of thin films obtained according to different substrate processing methods;

[0040] Figure 12 This is a diagram of the substrate processing method according to an embodiment;

[0041] Figure 13 This is a diagram of the substrate processing method according to an embodiment;

[0042] Figure 14 This is a diagram of the substrate processing method according to an embodiment;

[0043] Figure 15 This is a diagram showing the state of the thin film formed by the above-mentioned substrate treatment method after isotropic etching;

[0044] Figure 16 A substrate processing method according to an embodiment of the present disclosure is shown; and

[0045] Figure 17A and 17B The extent of wet etching of the thin film on the sidewall of the patterned structure is shown in the presence or absence of plasma purging, according to an example of this disclosure. Detailed Implementation

[0046] Reference will now be made in detail to embodiments, examples of which are shown in the accompanying drawings, wherein similar reference numerals always denote similar elements. In this respect, the embodiments may take different forms and should not be construed as limited to the description set forth herein. Therefore, the embodiments are described below only by reference to the accompanying drawings to explain aspects of this specification. As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. When an expression such as “at least one of…” precedes the list of elements, it modifies the entire list of elements and does not modify the individual elements in the list.

[0047] It will be understood that although the terms “first,” “second,” etc., may be used herein to describe various components, parts, regions, layers, and / or portions, these components, parts, regions, layers, and / or portions should not be limited by these terms. These terms do not indicate any order, quantity, or importance, but are used only to distinguish one component, region, layer, and / or portion from another. Therefore, without departing from the teachings of the embodiments, the first component, part, region, layer, or portion discussed below may be referred to as the second component, part, region, layer, or portion.

[0048] In this specification, the term "gas" can include evaporated solids and / or liquids, and can include a single gas or a mixture of gases. In this specification, the process gas introduced into the reaction chamber via a spray nozzle can include precursor gases and additive gases. Precursor gases and additive gases can typically be introduced as a mixed gas or can be introduced independently into the reaction space. Precursor gases can be introduced together with a carrier gas, such as an inert gas. Additive gases can include diluent gases, such as reactant gases and inert gases. Reactant gases and diluent gases can be introduced into the reaction space mixed or separately. Precursors can include two or more precursors, and reactant gases can include two or more reactant gases. Precursors are gases that are chemisorbed onto a substrate and typically contain a metalloid or metallic element that constitutes the main structure of the matrix forming the dielectric film, and the reactant gas used for deposition is a gas that reacts with the precursor chemisorbed onto the substrate when excited to immobilize an atomic layer or monolayer on the substrate. The term "chemisorbed" can refer to chemically saturated adsorption. Gases other than process gases, i.e., gases introduced without passing through a spray nozzle, can be used to seal the reaction space and may include sealing gases such as inert gases. In some embodiments, the term "membrane" may refer to a layer that extends continuously in a direction perpendicular to the thickness direction and is substantially without pores to cover the entire target or associated surface, or it may refer to a layer that covers only the target or associated surface. In some embodiments, the term "layer" may refer to a structure or synonym of a membrane or non-membrane structure of any thickness formed on a surface. A membrane or layer may include discrete single membranes or layers or multiple membranes or layers having certain properties, and the boundaries between adjacent membranes or layers may be clear or unclear, and may be set based on the physical, chemical and / or some other properties, formation process or sequence and / or function or purpose of adjacent membranes or layers.

[0049] In this disclosure, the phrase "containing Si-N bonds" can refer to being characterized by Si-N bonds, having a main framework mainly composed of Si-N bonds, and / or having substituents mainly composed of Si-N bonds. The silicon nitride layer can be a dielectric layer containing Si-N bonds, and can include a silicon nitride layer (SiN) and a silicon oxynitride layer (SiON).

[0050] In this disclosure, the term "same material" should be interpreted as meaning that the main components (composition) are the same. For example, when both the first layer and the second layer are silicon nitride layers and are formed of the same material, the first layer may be selected from Si2N, SiN, Si3N4, and Si2N3, and the second layer may also be selected from the group above, but its specific film quality may be different from that of the first layer.

[0051] Furthermore, in this disclosure, the operable range can be determined based on routine operations, any two variables can constitute the operable range of a variable, and any indicated range can include or exclude endpoints. Additionally, the value of any indicated variable can refer to an exact value or an approximate value (whether or not they are indicated as "approximately"), can include equivalents, and can refer to averages, medians, representative values, multi-values, etc.

[0052] In this disclosure, without specifying conditions and / or structures, those skilled in the art can readily provide such conditions and / or structures through conventional experimentation, in accordance with this disclosure. In all described embodiments, any component used in the embodiments may be replaced with its equivalent for intended purposes, including components explicitly, necessary, or essentially described herein, and furthermore, this disclosure can be similarly applied to apparatuses and methods.

[0053] In the following description, embodiments of the present disclosure will be illustrated with reference to the accompanying drawings. Variations in the illustrated shapes, for example, due to manufacturing techniques and / or tolerances, are to be expected in the drawings. Therefore, embodiments of the present disclosure should not be construed as limited to a particular shape of the area shown herein, but may include, for example, shape deviations caused by the manufacturing process.

[0054] Figure 1 This is a flowchart of a substrate processing method according to an embodiment of the present invention.

[0055] Reference Figure 1 The substrate processing method may include an operation S110 of forming at least one layer and an operation S120 of applying plasma under a first processing condition. Operations S110 and S120 may be repeated multiple times as a group, and a thin film may be formed on the substrate by repetition. The substrate processing method may also include an operation S150 of applying plasma under a second processing condition different from the first processing condition.

[0056] During operation S110, which forms at least one layer, a thin film can be formed on the stepped structure. That is, a thin film can be formed on a stepped structure having an upper surface, a lower surface, and a side surface between the upper and lower surfaces. The stepped structure can be a structure with a high aspect ratio, and the aspect ratio can be, for example, greater than or equal to width:height = 1:10. To form a conformal thin film on such a high aspect ratio stepped structure, an atomic layer deposition (ALD) process can be used. In particular, a plasma atomic layer deposition (PEALD) process can be used.

[0057] During operation S110, which forms at least one layer, an atmosphere can be configured to reduce the mean free path of plasma ions and de-directionalize them (i.e., increase the random motion of plasma ions). Such an atmosphere can facilitate the formation of conformal films on stepped structures with high aspect ratios. To achieve this atmosphere, a high-pressure atmosphere (e.g., 10 to 20 Torr) can be formed. In another embodiment, a low-power atmosphere (e.g., 200 W to 500 W) can be formed to achieve this atmosphere. In yet another embodiment, a high-temperature atmosphere can be formed to achieve this atmosphere.

[0058] During operation S110, which forms at least one layer, plasma can be used to form the layer. For example, operation S110 may include supplying a first gas, purging the first gas, and supplying a second gas and applying plasma to form the first layer. By applying plasma, the second gas can be excited to make it reactive, and the reactive second gas can react with the first gas to form the first layer.

[0059] The first gas may include a material chemically adsorbed onto the substrate as a source gas. The second gas may include a material reactive with the first gas, particularly a material reactive with the first gas in a plasma atmosphere. In an alternative embodiment, the supply of the second gas and the application of plasma may be performed simultaneously. In another embodiment, the application of plasma may be performed after the supply of the second gas.

[0060] The operation S110 for forming at least one layer can be performed multiple times (e.g., a cycles). More specifically, a group-cycle GC including the operation S110 for forming at least one layer and the operation S120 for applying plasma under the first processing conditions can be performed multiple times. The operation S110 for forming at least one layer can be performed multiple times during a group-cycle GC. Therefore, during one cycle, the supply of a first gas, the purging of the first gas, and the supply of a second gas and the application of plasma to form a second layer, which are included in the operation S110 for forming at least one layer, can be performed multiple times.

[0061] After the operation S110 of forming at least one layer, the operation S120 of applying plasma under the first processing condition is performed. The operation S120 of applying plasma under the first processing condition can be performed for a specific time (e.g., b seconds). By applying plasma under the first processing condition, the bonding structure of a portion of at least one layer can be changed. During the operation S120 of applying plasma under the first processing condition, the plasma ions can be set to be directional. On the other hand, as described above, during the operation S110 of forming at least one layer, the plasma ions can be set to be non-directional.

[0062] Directed plasma ions can alter the bonding structure of a portion of a thin film. For example, when forming a thin film on a stepped structure with a high aspect ratio, the plasma ions can be oriented to face either the upper or lower surface of the stepped structure. In this case, the plasma ions can change the bonding structure of the thin film formed on the upper or lower surface of the stepped structure. Conversely, directed plasma ions may not affect the bonding structure of the thin film formed on the side surface of the stepped structure.

[0063] As described above, in operation S110, which forms at least one layer, the pressure in the reaction space can be maintained at a first pressure (e.g., high pressure) while the second gas is supplied and plasma is applied, so that the random movement of the reactant gas can be increased. Conversely, in operation S120, which applies plasma under the first processing conditions, the pressure in the reaction space can be maintained at a second pressure (e.g., low pressure) that is lower than the first pressure, so that the movement of the reactant gas is directional.

[0064] Furthermore, in operation S110, which forms at least one layer, the power supplied during operation S110 can be maintained at a first power value (e.g., a low power value), so that the reactant gas is less affected by the power (i.e., the plasma ions become non-directional). Conversely, in operation S120, which applies plasma under the first processing conditions, the power supplied during operation S120 can be maintained at a second power value (e.g., a high power value) higher than the first power value, so that the reactant gas is more affected by the power (i.e., the plasma ions become directional).

[0065] The operation S110 of forming at least one layer and the operation S120 of applying plasma under the first processing condition can be defined as a grouped cyclic GC, and the grouped cyclic GC can be executed repeatedly. In other words, in operation S100, the X value is set to 1 before the grouped cyclic GC is executed, and in operation S140, after the grouped cyclic GC including the operation S110 of forming at least one layer and the operation S120 of applying plasma under the first processing condition is executed, the X value is increased, and in operation S130, when the X value reaches a specific value, the grouped cyclic GC is terminated and subsequent operations are executed.

[0066] As a subsequent operation, operation S150 of applying plasma under the second processing condition is performed. Operation S150 of applying plasma under the second processing condition can be performed for a specific duration (e.g., y seconds). By applying plasma under the second processing condition, the bonding structure of at least a portion of one layer can be further altered. During operation S150 of applying plasma under the second processing condition, the plasma ions can be oriented.

[0067] For example, plasma ions can be directed toward at least one layer. In this case, since the plasma ions are incident toward at least that layer, the portion of the binding structure altered in at least one layer will be the portion formed on the upper and lower surfaces of the patterned structure. When the plasma power is above a threshold, the portion formed on the upper and lower surfaces of at least one layer will be weakened, and when the plasma power is below a threshold, the portion formed on the upper and lower surfaces of at least one layer will be dense.

[0068] The commonality between operation S120, which applies plasma under the first processing condition, and operation S150, which applies plasma under the second processing condition, is that they alter the bonding structure of the thin film. However, because the first and second processing conditions are different, the thickness range of the thin film whose bonding structure is altered by the first processing condition is different from the thickness range of the thin film whose bonding structure is altered by the second processing condition.

[0069] More specifically, when repeating the cycle including the operation S110 of forming at least one layer and the operation S120 of applying plasma under the first processing conditions, in the case of the initially formed layer (i.e., the first portion of the film adjacent to the stepped structure), the change in the bonding structure due to plasma application can accumulate. Meanwhile, in the case of the later formed layer (i.e., the second portion of the film away from the stepped structure), only a small amount of plasma application (or a single plasma application) is performed, so the change in the bonding structure may be relatively small.

[0070] To counteract this localized difference in the bonding structure, plasma under a second processing condition can be applied. For example, plasma under the second processing condition can be applied to cause a change in the bonding structure of the second portion of the film, which is far from the stepped structure, without affecting the bonding structure of the first portion of the film adjacent to the stepped structure. By applying plasma under the second processing condition, the difference between the bonding structure of the first portion and the bonding structure of the second portion can be reduced.

[0071] In one embodiment, a hydrogen-containing gas is supplied during operation S150, in which plasma is applied under the second processing condition. By using the hydrogen-containing gas for plasma treatment, more Si-H bonds can be formed in the second portion of the film, away from the stepped structure. Therefore, the etching rate of the corresponding portion can be increased in the subsequent etching process.

[0072] In another embodiment, the same gas supplied during operation S150 of applying plasma under the second processing conditions may be supplied as the gas supplied in operation S150 of forming at least one layer. For example, supplying a first gas (e.g., a source gas), purging the first gas, and supplying a second gas (e.g., a reactant gas) and applying plasma to form the first layer may be performed during step S110 of forming at least one layer. The first gas (e.g., the source gas) may be supplied during operation S150 of applying plasma under the second processing conditions.

[0073] In this case, by applying plasma under the second processing conditions, a thin film can be formed additionally on the side surfaces of the stepped structure while maintaining the ion bombardment effect on the surfaces of the films formed on the upper and lower surfaces. This is particularly advantageous when weakening the bonding structure of the thin films, because the films formed on the side surfaces of the stepped structure are further formed, while the films formed on the upper and lower surfaces are weakened by the directional plasma, thereby increasing etching selectivity. Furthermore, the ion bombardment effect of plasma ions on the films formed on the side surfaces can be reduced due to the source gas supplied during plasma application.

[0074] After the plasma application operation S150 under the second processing condition, an isotropic etching operation S160 is performed on the thin film formed by performing multiple group cycles. For example, wet etching of the thin film can be performed. For example, wet etching can be performed by immersing a substrate on which a semiconductor device, such as a thin film, is deposited, in a liquid etching solution and etching the surface by chemical reaction. Since this wet etching is isotropic etching, such isotropic etching itself may not significantly affect the selective etching of the thin film formed on the stepped structure.

[0075] During the isotropic etching operation S160, etching selectivity can be achieved between the portion of the thin film whose bonding structure is altered and the rest of the thin film. In other words, by performing the plasma application operations S120 under the first processing condition and S150 under the second processing condition, the bonding structure of a portion of the thin film on the stepped structure (the thin film on the upper and lower surfaces of the stepped structure) is altered, thereby allowing a portion of the thin film to be removed during isotropic etching while retaining the rest. By removing a portion of the thin film on the stepped structure, the surface of the stepped structure can be exposed. Therefore, selective etching of the thin film can be achieved by a subsequent etching process. Thus, a patterned thin film formed on a region of the stepped structure can be formed without a separate additional photolithography process.

[0076] According to an embodiment of the present invention, a combination of operation S120, which applies plasma under a first processing condition, and operation S150, which applies plasma under a second processing condition different from the first processing condition, is utilized. Compared to the case where only one processing condition of plasma is applied, by combining and applying plasmas with different processing conditions, uniform etching selectivity can be achieved over the entire thickness range of the thin film formed on the stepped structure.

[0077] When operation S120, which applies plasma only under the first processing condition, is performed, regions where plasma is applied multiple times appear with repeated cycles. Therefore, by applying plasma multiple times, etching selectivity increases in the deeper portions of the film, while etching selectivity relatively decreases at the surface of the film. With low etching selectivity at the surface, productivity decreases because the film thickness needs to be deposited to be thicker than the target thickness in order to form a side film of appropriate thickness.

[0078] When only operation S150, which applies plasma under the second processing condition, is performed, high etching selectivity can be achieved through the ion bombardment effect and / or the penetration of reactive substances (e.g., hydrogen ions) into the film. However, the bombardment effect and the penetration of reactive substances increase the likelihood of defects in the substrate. To prevent this, when the plasma power is reduced or the penetration power of the reactive substances is reduced, the etching selectivity at deeper portions of the film (i.e., portions adjacent to the stacked structure and / or the substrate) decreases. As a result, to form a side film of appropriate thickness, the film thickness needs to be deposited to be thicker than the target thickness, thus reducing productivity.

[0079] By combining the operation S120 of applying plasma under the first processing condition and the operation S150 of applying plasma under a second processing condition different from the first processing condition, their respective shortcomings can be overcome. In other words, by combining them, a significantly improved effect can be achieved compared to performing the plasma application process alone.

[0080] The change in the bonding structure of a portion of the thin film caused by plasma ions can be either a weakening or a densification of the bonding structure. In the following description, embodiments will be presented in more detail with the weakening of the bonding structure as an example.

[0081] An atmosphere can be set such that during operation S120 of applying plasma under the first processing condition and operation S150 of applying plasma under the second processing condition, the plasma ions are directional. The ion bombardment effect of the directional plasma ions can weaken a portion of the film's bonding structure.

[0082] More specifically, the plasma ions can have an orientation perpendicular to the upper and lower surfaces of the stepped structure. Therefore, the bonding structure of the upper and lower surfaces of the film can be weakened. Consequently, the film on the upper and lower surfaces of the stepped structure can be removed by subsequent isotropic etching operation S160, while the film on the side surfaces of the stepped structure can be retained.

[0083] During the first set of cycles, operation S110 for forming at least one layer can be performed to have multiple sub-cycles. During each sub-cycle, supplying a first gas, purging the first gas, and supplying a second gas and applying plasma can be performed to form the first layer.

[0084] During the first set of cycles and after the sub-cycles, plasma can be applied for a specific duration under the first processing conditions. By applying plasma to the first layer under the first processing conditions, the wet etch rate (WER) of a portion of the first layer can be increased due to the ion bombardment effect of the plasma ions.

[0085] This will end the first set of cycles and begin the second set of cycles. During the second set of cycles, operation S110 for forming at least one layer can be performed to have multiple sub-cycles. The second layer formed during the second set of cycles will be formed on the first layer. In each sub-cycle of the second set of cycles, supplying a first gas, purging the first gas, and supplying a second gas and applying plasma can be performed to form the second layer.

[0086] During the second set of cycles and after the sub-cycle used to form the second layer, plasma can be applied for a specific duration under the first processing conditions. By applying plasma to the second layer under the first processing conditions, the WER of a portion of the second layer can increase due to the ion bombardment effect of the plasma ions. Simultaneously, the applied plasma can affect not only the second layer but also the first layer beneath it. Therefore, the WER of a portion of the first layer can be further increased, thus the WER of the first layer can be greater than that of the second layer.

[0087] After the first and second sets of cycles, plasma under second processing conditions can be applied to both the first and second layers. As mentioned above, the second processing conditions can differ from the first processing conditions. In particular, the second processing conditions can weaken the upper second layer without significantly affecting the lower first layer. For example, the second processing conditions can generate a reactive substance with low permeability, which can weaken only the upper second layer without significantly affecting the lower first layer. As a result, by applying the plasma under the second processing condition, the difference between the WER of the first and second layers can be reduced.

[0088] Although this disclosure describes the application of plasma under second processing conditions after a second set of cycles, additional set cycles can be performed between the second set of cycles and the application of plasma under the second processing conditions. For example, a third set of cycles can be performed after the second set of cycles. During the third set of cycles, operation S110 for forming at least one layer can be performed to have multiple sub-cycles. The third layer formed during the third set of cycles will be formed on the first and second layers.

[0089] Subsequently, plasma under the first processing conditions is applied to the third layer, and due to the ion bombardment effect of plasma ions, the WER of a portion (parts of the upper and lower surfaces of the stepped structure) can be increased (see [link to documentation]). Figure 6 As the cycle is repeated, the first portion of the film adjacent to the substrate (e.g., the first layer) will have a higher WER than the second portion of the film farther from the substrate (e.g., the second layer).

[0090] To reduce the variation in WER (Waste Erroneous) values, plasma application under a second processing condition is performed after the group cycle. In other words, by repeating the group cycle, the plasma under the first processing condition is repeatedly applied to increase the etch selectivity of the deeper portions of the film while decreasing the etch selectivity of the film surface. Therefore, plasma is applied under the second processing condition to address this issue. By applying plasma under the second processing condition, the etch selectivity of the film surface can be increased, and thus uniform etch selectivity can be achieved, regardless of the film thickness (or depth).

[0091] Figure 2 This is a view of a substrate processing method according to an embodiment. The substrate processing method according to the embodiment may be a variation of the substrate processing method according to the above embodiment. Hereinafter, the embodiments will not be described again.

[0092] According to embodiments of the present invention, a substrate treatment method can be proposed to increase the WER of films deposited on the upper and lower portions of a stepped structure and to keep the WER constant over time. For example, a first sub-step of uniformly depositing a hard and uniform film on the stepped structure can be performed, a second sub-step of performing plasma treatment to increase the etching selectivity of films deposited on the sides, upper and lower portions of the stepped structure, and a third sub-step of performing plasma treatment using a hydrogen-containing gas (e.g., H2).

[0093] Reference Figure 2During the first sub-step (step 1), a hard and uniform SiN film is uniformly deposited on the stepped structure. For example, the SiN film can be deposited by plasma atomic layer deposition. The first sub-step (step 1) can be repeated multiple times, and a SiN film with a specific thickness can be formed. During the second sub-step (step 2), a plasma treatment is performed for b seconds. The first and second sub-steps are grouped into a cycle, and the film deposition is repeated multiple times (x cycles) according to the desired thickness. In the first sub-step (step 1), a high processing pressure and low plasma power are applied to weaken the directionality (linearity) of the plasma reactive material and uniformly deposit a hard and uniform SiN film in the stepped structure. In the second sub-step (step 2), the etching selectivity of the film deposited on the sides, top, and bottom of the stepped structure is increased by providing a low processing pressure and high plasma power to improve the directionality (linearity) of the plasma reactive material.

[0094] The third sub-step (step 3) is a plasma treatment step using hydrogen-containing gas, which is maintained for y seconds. Maintaining low pressure and high plasma power allows H ions generated by the hydrogen-containing gas to easily penetrate into the film. H ions can form weak bonds with SiN or weaken the Si-N bonding structure. Weakening the bonding structure with H ions maximizes the effect at the surface where the plasma treatment is performed directly. Here, a low H2 flow rate is maintained to prevent H ion accumulation (i.e., to prevent weakening of the film in deeper regions). For example, in the third sub-step (step 3), the H2 flow rate can be performed at a condition below 100 sccm. The third sub-step (step 3) is a step to adjust the etch selectivity at the surface of the deposited film to be similar to the etch selectivity at the deeper regions of the deposited film.

[0095] In an alternative embodiment, in the plasma treatment of the third sub-step (step 3), other gases that readily penetrate the film can be used besides hydrogen-containing gases. Gases such as He to Ar can be used. Wet etching is then performed to retain the SiN film on the sidewalls and remove the SiN film on the upper and lower walls.

[0096] Figure 3 This is a view of the base processing method according to an embodiment. Figure 4 This is a diagram of a substrate processing apparatus in which a substrate processing method is performed; the substrate processing method according to the embodiment may be a variation of the substrate processing method according to the above embodiment. In the following, the embodiments will not be described again.

[0097] Reference Figure 4The substrate processing apparatus may include at least one reactor. An upper electrode (e.g., a spray head) connected to an RF generator and a lower electrode disposed opposite to the upper electrode may be disposed in the reactor. The substrate may be loaded onto the lower electrode, such as a heating block, and a plasma process may be performed on the substrate. In some embodiments, the reactor may be a direct plasma reactor.

[0098] The layer formed on the substrate using a substrate processing apparatus can be a silicon nitride layer. Plasma-ion layer deposition (PEALD) can be used to form the silicon nitride layer. As the Si source, precursors such as dichlorosilane (SiH₂Cl₂), aminosilane, or iodosilane can be used. As the nitrogen source, nitrogen gas can be used. Nitrogen gas reacts with the physically adsorbed silicon source on the substrate when activated by plasma, but does not react with the silicon source when not activated by plasma; therefore, it can be used as a purge gas.

[0099] Reference Figure 3 The group cycle includes two sub-steps: a first sub-step (step 1) and a second sub-step (step 2), and each sub-step can be repeated for a cycles and b cycles respectively. These sub-steps can be included in the group cycle, which can be repeated. The first sub-step (step 1) is the step of uniformly depositing a SiN film on the patterned structure, and the second sub-step (step 2) is the plasma processing step.

[0100] During the second sub-step (step 2), the bonding structure of the SiN film deposited on the upper surface of the patterned structure in a direction perpendicular to the direction of free radical propagation can be weakened. Therefore, in the second sub-step (step 2), to enhance the plasma ion bombardment effect, an atmosphere with lower processing pressure and higher plasma power can be set compared to the first sub-step (step 1). After group cycling, wet etching is performed on the substrate in a 100:1 diluted hydrogen fluoride (DHF) solution, which removes the SiN film deposited on the upper surface of the patterned structure while retaining the SiN film deposited on the side surfaces of the pattern.

[0101] Simultaneously, during wet etching, not only the SiN film deposited on the upper surface of the stepped structure but also the SiN film deposited on the side surfaces of the stepped structure are etched. However, the etching rate of the SiN film on the upper surface is high, resulting in the SiN film remaining on the side surfaces. That is, to achieve the desired SiN film thickness on the sidewalls, a thicker SiN film needs to be formed when actually depositing the SiN film. In other words, when the etching rate of the SiN film on the upper surface of the patterned structure is faster, the SiN film on the sidewalls can be achieved with the same thickness even if a thinner SiN film is formed during deposition. This will save processing time and increase the substrate processing speed per hour. Figure 5 The process is shown in which Figure 5(a) shows the SiN film formed on the stepped structure. Figure 5 (b) shows the SiN film retained on the sidewalls of the stepped structure after wet etching.

[0102] Reference Figure 5 (a) SiN film is deposited on the patterned structure with uniform thickness. Figure 5 In A, the upper membrane d = the side membrane c). Because through... Figure 3 The second sub-step (step 2) disrupts the bonding structure of the upper SiN film, thus the upper SiN film d is etched faster than the side SiN film c during wet etching. The thickness of the side SiN film is also reduced to some extent, but the etching rate of the side SiN film is slower than that of the upper SiN film. Therefore, only the side SiN film is retained after wet etching. Figure 5 (b) in a)(see Figure 5 (b) That is, in order to achieve the desired thickness of the side film a, the etching rate of the upper film d needs to be considered to form the additional film b.

[0103] In other words, the etch rate Ed of the upper film d and the etch rate Ec of the side film c determine the selectivity, and the faster the etch rate Ed on the upper surface, the better the selectivity. Figure 5 As shown, considering the difference in etching rates between the upper film d and the side film c, a film (a+b) thicker than the required side film a is deposited.

[0104] Figure 6 It shows that according to Figure 3 The substrate processing method of the embodiment. Refer to Figure 6 A first SiN layer a, a second SiN layer b, and a third SiN layer c are sequentially formed according to an atomic layer deposition method. Each layer is subjected to nitrogen plasma treatment during one cycle (step 2). For ease of understanding, this embodiment shows the execution of three sets of cycles GC1, GC2, and GC3 (x = 3), with only one nitrogen plasma treatment (step 2) performed for each layer (b = 1).

[0105] exist Figure 6 In the diagram, the nitrogen plasma treatment performed for each group cycle is indicated by an asterisk. The first marker GC1 indicates the nitrogen free radicals applied during the group cycle for depositing the first layer a, the second marker GC2 indicates the nitrogen free radicals applied during the group cycle for depositing the second layer b, and the third marker GC3 indicates the nitrogen free radicals applied during the group cycle for depositing the third layer c.

[0106] For example, nitrogen radicals disrupt the bonding structure of the SiN layer deposited on the upper surface of the pattern by performing nitrogen plasma treatment with a plasma power exceeding the critical plasma power. Although nitrogen plasma was applied in the above experiments, the bonding structure of the film could be disrupted more easily by applying Ar plasma, which contains large and heavy elements.

[0107] like Figure 6 As shown, it should be noted that the plasma applied in the second sub-step (step 2) (which is the plasma treatment step) when depositing each film also affects the underlying film. That is, when forming each layer, in the second sub-step (step 2) of the group cycle, the nitrogen plasma treatment is performed only once (b=1), but the underlying layer undergoes further plasma treatment. In other words, when the first layer a, the second layer b, and the third layer c are deposited sequentially, the first layer a, which is adjacent to the patterned structure, undergoes three plasma treatments, the second layer b, which is on the first layer a, undergoes two plasma treatments, and the third layer c, which is far from the patterned structure, undergoes one plasma treatment. This means that the etching characteristics of the entire bulk film (a+b+c) are non-uniform, and the WER is higher towards the bottom of the film (Ea). <Eb<Ec)。

[0108] Figure 7 The variation of wet etching rate in a SiN thin film is shown, which is based on Figure 6 The graph shows a bulk film. The horizontal axis represents the variation in etching time, and the vertical axis represents the variation in etching rate with respect to etching time. The relationship between the horizontal and vertical axes corresponds to the variation in etching rate from the surface to the interior of the bulk film. As shown in the graph, the etching rate is not uniform from the surface to the depth of the SiN film. That is, it can be seen that the WER is smaller in the surface portion of the SiN film where less plasma is applied, while the WER is larger in the deeper portion of the SiN film where a large amount of plasma is applied through repeated cycles.

[0109] When the wet etching characteristics of a bulk film are non-uniform, the selectivity between the top and side surfaces decreases. For example, when the etching rate of the film on the top surface is low in the initial stage of a wet etching process following deposition, the amount of film etched on the side surfaces is the same as that on the top surface. Conversely, when the etching rate of the deeper portions of the film is low in a later wet etching process following deposition, the amount of film etched on the side surfaces is the same as that in the deeper portions of the film. As a result, as... Figure 8 As shown, when the thin film on the upper part of the etched pattern structure is etched, only the thin film with a thickness e less than or equal to the desired thickness a is retained on the side surface, and as a result, the selectivity between the upper and side films is reduced.

[0110] Therefore, considering this issue, it is necessary to deposit films of relatively thick thickness during the film formation operation. This means that increased source and gas consumption will increase the cost of ownership (COO) of the device and reduce the substrate flux per unit time.

[0111] Figure 9 This is a view of a substrate processing method according to an embodiment. The substrate processing method according to the embodiment may be a variation of the substrate processing method according to the above embodiment. Hereinafter, the embodiments will not be described again.

[0112] Reference Figure 9 A substrate treatment method is disclosed that improves the selectivity of bulk films by making the etching rate uniform across their entire thickness. This substrate treatment method can be performed in a direct plasma deposition apparatus consisting of an upper electrode and a lower electrode, such as... Figure 4 As shown.

[0113] exist Figure 9 In the illustrated embodiment, with Figure 3 Compared to the previous embodiment, a third sub-step (step 3) for performing plasma post-treatment is added. First, the two sub-steps (step 1 and step 2) are repeated several times. That is, the first sub-step (step 1) is repeated a cycles, and the second sub-step (step 2) is repeated b cycles. Then, a group of cycles is executed to repeat this repetition several times (x cycles). After the group of steps is completed, the third sub-step (step 3) for post-plasma treatment is performed. The post-plasma treatment can be repeated several times (e.g., y cycles). Each step will be described in more detail below.

[0114] 1. First sub-step (Step 1): Conformal deposition

[0115] As the first sub-step, this step involves depositing a SiN film on the pattern. Because a uniformly thick SiN film is deposited, the thickness of the SiN film deposited on the top and sides of the pattern is the same. Halogen-based source gases (e.g., dichlorosilane (DCS)), aminosilane, or iodosilane-based source gases can be used as the silicon source, while nitrogen can be used as the nitrogen source. When activated with plasma, nitrogen reacts with the silicon source to become a component of the film; however, when not activated with plasma, nitrogen can be used as a purge gas without reacting with the silicon source.

[0116] During the first sub-step, a SiN film is uniformly applied onto the patterned structure while source gas, reactor gas, and plasma are alternately supplied via the PEALD method, repeated several times (a cycle). The plasma power is reduced to allow free radicals to be supplied to the interior of the pattern. The plasma power ranges from 200 watts to 900 watts, preferably 500 watts.

[0117] Furthermore, by increasing the processing pressure to weaken the linearity of free radicals, more free radicals are allowed to be provided to the pattern side surfaces than to the bottom surface of the pattern, thereby promoting the formation of SiN films on the sides. In this step, the processing pressure is maintained at approximately 10 Torr to approximately 20 Torr.

[0118] 2. Second sub-step (step 2): Circulating plasma treatment

[0119] As a second sub-step, this step involves performing nitrogen plasma treatment on the SiN film deposited on the pattern. Specifically, this step aims to increase the etch selectivity between the films deposited on the upper and side surfaces. As described above, a plasma power higher than the critical plasma power is applied to disrupt the bonding structure of the film on the upper surface of the patterned structure in a direction perpendicular to the direction of free radical propagation, thereby resulting in a higher etch rate for the film on the upper surface than for the film on the side surfaces.

[0120] In this disclosure, although nitrogen gas with the same composition as the membrane is used, a heavier element, Ar gas, can be used to more easily disrupt the membrane's binding structure. In this step, plasma treatment is performed at a plasma power of about 700 watts to about 1000 watts, preferably about 700 watts, higher than in the first sub-step (step 1), to enhance the linearity of the free radicals and the ion bombardment effect.

[0121] Furthermore, to enhance ion bombardment on the upper and lower surfaces rather than the patterned sides, the processing pressure is set lower than that of the first sub-step (step 1). In this disclosure, the plasma treatment is performed at a processing pressure of about 1 Torr to about 5 Torr, preferably about 3 Torr. This step is also repeated several times (b cycles). In addition, the group step combining the first and second sub-steps is repeated several times (x cycles).

[0122] 3. Third sub-step (step 3): Post-plasma treatment

[0123] This step addresses the issue of uneven wet etching characteristics in SiN thin films. In this step, hydrogen is added to activate a nitrogen and hydrogen mixture using RF power. To promote free radical penetration into the film on the upper and lower surfaces of the pattern, the processing pressure is lower than in the deposition step (Step 1), and the plasma power is higher. This step is performed at a plasma power of 700 to 1000 watts, preferably 700 watts, higher than that of the deposition step (Step 1), to enhance free radical linearity and ion bombardment effect.

[0124] Furthermore, the processing pressure is set lower than that of the deposition step (step 1) to enhance ion bombardment on the upper and lower surfaces, rather than on the patterned sides. In this disclosure, the plasma treatment is performed at a processing pressure of about 1 Torr to about 5 Torr, preferably about 3 Torr. Hydrogen radicals form weak bonds with the SiN film or weaken the bonding structure of the SiN film, and the weakening effect of hydrogen radicals on the bonding structure is maximized on the surface directly subjected to plasma treatment. Therefore, the etch resistance of the film surface is weakened.

[0125] Furthermore, by supplying nitrogen radicals together, the ion bombardment of the SiN film on both the upper and lower surfaces can be enhanced, as well as the resulting weakening of the bonding structure. In this disclosure, although hydrogen, which is smaller and lighter than other elements, is used, helium can also be used. In another embodiment, only hydrogen may be supplied without supplying nitrogen.

[0126] Table 1 below shows exemplary experimental conditions applied to each step.

[0127] Table 1

[0128]

[0129] By employing the processing conditions shown in Table 1 above, the etch selectivity between the films deposited on the upper and side surfaces of the pattern can be improved when depositing thin films on the patterned structure. Furthermore, by utilizing the PEALD method to deposit a uniform film on the pattern (first sub-step (step 1)), the process of disrupting the bonding structure of the film on the upper surface of the pattern (second sub-step (step 2)), and the process of achieving uniform etch characteristics and a high etch rate (third sub-step (step 3)), higher etch selectivity and efficiency can be achieved for the RTS process compared to conventional techniques.

[0130] Figure 10 This is a diagram illustrating the etching characteristics of the thin film after processing according to this disclosure. (See diagram for example.) Figure 10 As shown, when the application is performed according to the conditions of this disclosure, that is, when the first to third sub-steps (step 1 + step 2 + step 3) are executed, the WER is constant and independent of time. That is, a constant WER can be ensured regardless of the position in the SiN thin film.

[0131] Meanwhile, in the embodiments of the first sub-step and the third sub-step (step 1 + step 3), it can be seen that although the hydrogen radicals supplied during the third sub-step (H2 post-plasma treatment) are effective in disrupting the bonding structure on the surface of the film, the bonding structure in the deeper parts of the film remains unchanged, causing the WER to decrease over time.

[0132] In the case of the first and second sub-steps (step 1 + step 2), it can be seen that although the nitrogen radicals supplied during the second sub-step (N2 cyclic plasma treatment) are effective in disrupting the bonding structure of the deep portion of the film, the bonding structure of the film surface is not changed, resulting in a low WER at the start of etching, which reduces etching selectivity.

[0133] Therefore, according to embodiments of the present invention, by combining the ion bombardment effect caused by nitrogen free radicals (N2 circulating plasma treatment) and the weakening of the etch resistance of the film surface (post-plasma treatment) caused by hydrogen free radicals, the etching rate can be further improved by further weakening the etch resistance over the entire thickness of the upper film.

[0134] Table 2

[0135]

[0136] Table 2 shows the results in Figure 10 The examples show the etching selectivity of the SiN film within a wet etching time of 80 seconds. Etching was performed in a 100:1 DHF solution. Based on the above... Figure 10 As shown in Table 2, compared to result 6.3 of the cyclic plasma treatment using nitrogen radicals (N2 cyclic plasma treatment), the result according to this disclosure increases to 21.5, thereby improving selectivity by 3.4 times or more. That is, in addition to the cyclic plasma treatment using nitrogen radicals (N2 cyclic plasma treatment), a further plasma treatment (Post PT) is performed using a hydrogen mixed gas (Post Plasma Treatment), which weakens the etch resistance of the film surface on the patterned structure, and then the upper surface film can be etched at a uniform and high etch rate. In other words, a thicker film can be left on the sides of the patterned structure, thereby achieving effective processing performance.

[0137] Figure 11 The results in Table 2 above are illustrated schematically. It can be seen that by performing the first to third sub-steps (step 1 + step 2 + step 3) according to this disclosure, the etch selectivity is significantly improved (see...). Figure 11 B). With only the first and second sub-steps performed, the side surface film remains below the desired thickness, while the entire upper surface film is etched (see [link]). Figure 11 A). However, when performing the first to third sub-steps (step 1 + step 2 + step 3), the desired film thickness was retained.

[0138] Figure 12 This is a view of a substrate processing method according to an embodiment. The substrate processing method according to the embodiment may be a variation of the substrate processing method according to the above embodiment. Hereinafter, the embodiments will not be described again.

[0139] Reference Figure 12 The source gas can be supplied during the third sub-step (step 3). In this step, the SiN film is further deposited by supplying the source gas. However, due to the high plasma power supplied during the third sub-step, the ion bombardment effect becomes dominant, and the density of the newly deposited SiN film on the upper surface is weakened. Meanwhile, the newly deposited SiN film on the side surface has a relatively weak ion bombardment effect and a relatively high density.

[0140] Furthermore, due to the low-pressure atmosphere formed during the third sub-step, the ion bombardment effect is also applied to the bottom surface of the patterned structure, in addition to the top surface. That is, since the density of the newly deposited SiN film on the top and bottom surfaces is weakened, while the density of the SiN film on the side surfaces is relatively increased, the etching selectivity can be improved in subsequent isotropic etching operations (e.g., wet etching operations).

[0141] Figure 13 This is a view of a substrate processing method according to an embodiment. The substrate processing method according to the embodiment may be a variation of the substrate processing method according to the above embodiment. Hereinafter, the embodiments will not be described again.

[0142] refer to Figure 13 The process of forming a first layer is performed in step S310. The first layer can be formed to have a uniform thickness over a patterned structure. The first layer can include multiple layers, and these multiple layers can be formed by repeatedly performing cycles of the atomic layer deposition process. For example, the first layer can be an insulating layer.

[0143] Subsequently, operation S320, which alters the properties of a portion of the first layer, is performed. For example, the bonding structure of a portion of the first layer can be altered by applying directional energy under the first processing condition. More specifically, a first plasma under the first processing condition can be applied in a direction substantially perpendicular to the first layer formed on the upper and lower surfaces of the patterned structure, and the bonding structure of the portion of the first layer formed on the upper and lower surfaces of the patterned structure can be altered due to the first plasma.

[0144] Subsequently, operation S330, forming a second layer on the first layer, is performed. In this example, at least one layer may be inserted between the first and second layers. The second layer may be formed to have a uniform thickness on the first layer. The second layer may include multiple layers, and these multiple layers may be formed by repeatedly performing cycles of the atomic layer deposition process. For example, the second layer may be formed from the same material as the first layer.

[0145] Subsequently, operation S340, which alters the characteristics of portions of the first and second layers, is performed. For example, the bonding structure of portions of the first and second layers can be altered by applying directional energy under the first processing condition. More specifically, a second plasma under the first processing condition can be applied in a direction substantially perpendicular to the second layer formed on the upper and lower surfaces of the patterned structure, and due to the second plasma, the bonding structure of portions of the first layer formed on the upper and lower surfaces of the patterned structure and portions of the second layer formed on the upper and lower surfaces of the patterned structure can be altered.

[0146] Subsequently, operation S350 is performed to reduce the difference between the characteristics of the first layer and the characteristics of the second layer. When the above characteristic-changing operation is repeated, the lower layer repeatedly receives energy, resulting in a difference in characteristics between the upper and lower layers. For example, the degree of change in the bonding structure of a portion of the lower first layer may be greater than the degree of change in the bonding structure of a portion of the upper second layer. Therefore, additional operation S350 can be performed to reduce the difference between the characteristics of a portion of the first layer and a portion of the second layer.

[0147] As an example of additional operation S350, energy (e.g., a third plasma) can be applied in a direction substantially perpendicular to the second layer formed on the upper and lower surfaces of the patterned structure, and this energy can further alter the bonding structure of the portion of the second layer formed on the upper and lower surfaces of the patterned structure. More specifically, the bonding structure of a portion of the second layer can be altered by applying directional energy under second processing conditions.

[0148] The second processing condition differs from the first processing condition used in the aforementioned characteristic-changing operation, and in particular, the second processing condition can be set to affect only the bonding structure of the second layer without affecting the bonding structure of the first layer. That is, the first processing condition can be used during the application of the first plasma and the second plasma, and the second processing condition, different from the first processing condition, can be used during the application of the third plasma.

[0149] By applying a third plasma under the second processing conditions, the bonding structure of the upper second layer can be altered without changing the bonding structure of the lower first layer. Therefore, the difference between the degree of change in the bonding structure of a portion of the lower first layer and the degree of change in the bonding structure of a portion of the upper second layer can be reduced.

[0150] Figure 14 This is a view of a substrate processing method according to an embodiment. The substrate processing method according to the embodiment may be a variation of the substrate processing method according to the above embodiment. Hereinafter, the embodiments will not be described again.

[0151] Reference Figure 14The operation S510 involves performing a repeated cycle to form a thin film. The thin film may include, for example, a nitride film, specifically, a silicon nitride film. The cycle may include supplying a first gas (e.g., a source gas) to the substrate and supplying a second gas (e.g., a reactant gas) that is reactive with the first gas.

[0152] During repeated cycles, energy can be applied. Due to the repeated application of energy, the WER of the first portion of the film adjacent to the substrate can be higher than that of the second portion of the film far from the substrate. That is, in the film adjacent to the substrate, the WER is increased by repeatedly applying energy during film formation. However, the film far from the substrate can only be activated a limited number of times in the latter half of film formation, so the WER does not increase.

[0153] Therefore, an additional operation S520 can be performed to counteract this WER difference. That is, an operation S520 can be performed to further reduce the difference between the WER of the first part and the WER of the second part. For example, by setting the processing conditions so that energy can be applied to the part adjacent to the exposed surface of the film, the WER of the part adjacent to the exposed surface of the film (i.e., the second part) can be increased. As a result, the variation in WER caused by the position of the film due to repeated cycles can be reduced, and a uniform WER can be achieved over the entire thickness range of the film during the subsequent wet etching operation S530.

[0154] Figure 15 The shape of the SiN thin film on the stepped structure is shown at the thin film etching rate according to the above-described substrate processing method. Figure 15 (a) shows the shape of the film before wet etching. A film of a certain thickness is uniformly deposited on the stepped structure.

[0155] Figure 15 (b) illustrates an example of depositing and wet etching a thin film using a first sub-step and a second sub-step. Because the etching rates at the top and bottom of the stepped structure are low at the start of wet etching, an increased over-etch rate is required to remove the upper and lower films of the stepped structure, resulting in thinner films on the sides of the stepped structure. Therefore, when a certain thickness of side film is required, the film deposition thickness needs to be increased, reducing productivity.

[0156] Figure 15 (b) illustrates an example of depositing and wet etching a thin film using a first and third sub-step. The etching rate is high only at the start of wet etching and decreases rapidly and converges to a specific value as etching progresses. Therefore, patterning is only possible when the side film is thin, and when the side film is thick, the film remains in the upper and lower parts of the stepped structure.

[0157] Figure 15(d) illustrates an example of depositing and wet etching a thin film using a first sub-step, a second sub-step, and a third sub-step, according to an embodiment of the present invention. Since the etching rate is constant and high over time, the upper and lower films of the stepped structure can be etched in a short time to reduce side film loss. Furthermore, since the thickness of the side film retained after wet etching is increased, the applications to which this process can be applied can be expanded.

[0158] Figure 16 This is a diagram illustrating a substrate processing method according to an embodiment. The substrate processing method according to the embodiment may be a variation of the substrate processing method according to the above embodiment. In the following, a repeated description of the embodiments will not be given.

[0159] Reference Figure 16 The substrate treatment method may include forming at least one layer (S110), applying plasma under a first treatment condition (S120), applying plasma under a second treatment condition different from the first treatment condition (S150), and purging the plasma under the second treatment condition (S155), followed by an isotropic etching operation (S160). Plasma purging here refers to purging plasma products, such as plasma-generated ions or free radicals. The plasma purging operation (S155) may correspond to... Figure 9 Step 18.

[0160] By performing a plasma purification operation (S155) under the second processing condition, the etching selectivity of the thin film formed on the patterned structure can be improved. More specifically, an operation of applying plasma (S150) is performed to change the bonding structure of a portion of the thin film on the patterned structure and to activate ions or free radicals retained between the patterned structures. By performing a plasma purging operation (S155), residual plasma products between the patterned structures can be removed.

[0161] In some embodiments, under the second processing condition, hydrogen-containing gas may be provided during the application of plasma. In this case, the hydrogen-containing gas can be removed from the reaction space during the plasma purging operation (S155) under the second processing condition. Hydrogen weakens the bonding structure of the film on the patterned structure, but it also provides hydrogen between the patterned structures and affects the film deposited on one side of the patterned structure to some extent. The hydrogen remaining between these patterned structures can be an inhibitory factor for improving etching selectivity. Therefore, by performing plasma purging (S155) under the second processing condition and removing the hydrogen remaining between the patterned structures, etching selectivity can be improved by minimizing the effect of hydrogen on the film on one side of the patterned structure.

[0162] In some embodiments, the application of plasma under the second processing condition (S150) and the plasma purging under the second processing condition (S155) can be performed in one cycle. That is, a cycle including operations (S150 and S155) can be repeated multiple times to form a thin film that meets specific conditions.

[0163] Figure 17 shows the degree of wet etching of the thin film on the sidewall of the patterned structure (S155) under the second processing condition, depending on the presence or absence of the plasma purging described above. Figure 17a shows the case without plasma purging operation, and Figure 17b shows the case with plasma purging operation added.

[0164] Referring to Figure 17a, a thin film is formed on the patterned structure without plasma purging. Because the thin film on the upper and lower parts of the patterned structure is removed by wet etching for 5 minutes after plasma treatment under the second processing condition without plasma purification, the film thickness on the sidewalls of the patterned structure decreases from 135 angstroms to 113 angstroms. That is, a wet etching rate of 4.4 angstroms per minute can be observed.

[0165] On the other hand, with the addition of plasma purging in Figure 17b, the wet etching rate is noticeably lower. After forming a thin film on the patterned structure, plasma treatment was performed under the second processing condition, followed by plasma purging. After 5 minutes of wet etching, the thin film on the upper and lower parts of the patterned structure was removed, and the film thickness on the sidewalls of the patterned structure decreased from 142 angstroms to 130 angstroms. That is, the wet etching rate reached 2.4 angstroms per minute.

[0166] Therefore, by purging, hydrogen gas around the sidewalls between the patterned structures is removed, minimizing the impact of hydrogen on the sidewalls. As a result, the weakening of the bonding structure of the thin film on the sidewalls is prevented, and a high etching selectivity is achieved.

[0167] During plasma purging under the second processing condition (S155), nitrogen can be used as the purge gas. That is, plasma products such as ions and free radicals can be purified by supplying and venting nitrogen into the reaction space. In some embodiments, vacuum purging can be applied during plasma purging under the second processing condition (S155) without a separate purge gas. In another embodiment, nitrogen purge gas and hydrogen can be supplied together during plasma purging under the second processing condition (S155). By supplying nitrogen purge gas and hydrogen together, pressure fluctuations can be reduced, allowing the process to proceed more stably.

[0168] Table 3 below shows the wet etching rate (S155) of each part of the patterned structure under the second processing condition, depending on whether the above-mentioned plasma cleaning is present.

[0169]

[0170] When a purge operation is added to Table 3 above, the etching rate generally decreases as hydrogen is removed from the reaction space. However, it can be seen that the etching selectivity between the film on the sidewalls of the patterned structure and the film on the upper surface is significantly improved compared to the case without a purge operation.

[0171] As described above, according to the present invention, by adding a purging operation and removing residual hydrogen near the sidewalls between the patterned structures during the hydrogen plasma processing operation, there is a technical effect that can improve the etching selectivity between the upper surface and the side surface of the patterned structure.

[0172] It should be understood that the embodiments described herein should be considered in a descriptive sense only and not for limiting purposes. The description of features or aspects in each embodiment should generally be considered applicable to other similar features or aspects in other embodiments. Although one or more embodiments have been described with reference to the accompanying drawings, those skilled in the art will understand that various changes in form and detail may be made without departing from the spirit and scope of the invention as defined by the following claims.

Claims

1. A substrate processing method comprising: forming a film on a substrate by performing a plurality of cycles, each cycle comprising forming at least one layer and applying plasma to the at least one layer under first processing conditions; and applying plasma to the film under second processing conditions different from the first processing conditions; wherein forming the at least one layer comprises: supplying a first gas; purging the first gas; and supplying a second gas and applying plasma to form a first layer; wherein, during the supplying the second gas and applying plasma to form the first layer, a pressure in a reaction space is maintained at a first pressure, and during the applying plasma under the first processing conditions, the pressure in the reaction space is maintained at a second pressure lower than the first pressure; wherein a power supplied during the applying plasma under the first processing conditions is greater than a power supplied during the supplying the second gas and applying plasma to form the first layer.

2. The substrate processing method according to claim 1, an atmosphere is set such that, during the applying plasma under the first processing conditions and the applying plasma under the second processing conditions, plasma ions have directionality.

3. The substrate processing method according to claim 1, during the applying plasma under the first processing conditions, a binding structure of a portion of the film is changed, and wherein during the applying plasma under the second processing conditions, the binding structure of the portion of the film is further changed.

4. The substrate processing method according to claim 3, further comprising an isotropic etching operation, during the isotropic etching operation, an etching selectivity between the portion of the film whose binding structure is changed and a remaining portion of the film is achieved. wherein 5. The substrate processing method according to claim 3, the at least one layer is formed on a stepped structure having an upper surface, a lower surface, and a side surface between the upper surface and the lower surface, and wherein the portion of the film corresponds to a portion of the film formed on the upper surface and the lower surface.

6. The substrate processing method according to claim 5, a repetition of the cycles results in a difference between a first binding structure of a first portion of the film adjacent to the stepped structure and a second binding structure of a second portion of the film away from the stepped structure, and wherein during the applying plasma under the second processing conditions, the difference between the first binding structure of the first portion and the second binding structure of the second portion is reduced.

7. The substrate processing method according to claim 5, further comprising an isotropic etching operation, after the isotropic etching operation, a film on the upper surface and the lower surface of the stepped structure is removed, and a film on the side surface of the stepped structure is retained. wherein 8. The substrate processing method according to claim 1, during the applying plasma under the second processing conditions, a hydrogen-containing gas is supplied.

9. The substrate processing method according to claim 1, ​ wherein, supplying the first gas during plasma application under the second processing condition different from the first processing condition.

10. The substrate processing method according to claim 1, wherein during a first cycle, the supplying of the first gas, the purging of the first gas, and the supplying of the second gas and plasma application are performed multiple times to form a first layer.

11. The substrate processing method according to claim 10, wherein during the first cycle, plasma under the first processing condition is applied to the first layer so that a WER of a portion of the first layer is increased due to an ion bombardment effect of plasma ions.

12. The substrate processing method according to claim 11, wherein during a second cycle after the first cycle, a second layer is formed on the first layer, wherein the forming of the second layer includes: supplying a first gas; purging the first gas; and supplying a second gas and plasma application to form the second layer.

13. The substrate processing method according to claim 12, wherein during the second cycle, plasma under the first processing condition is applied to the second layer and the first layer under the second layer so that WERs of a portion of the first layer and a portion of the second layer are increased due to an ion bombardment effect of plasma ions, wherein the WER of the first layer is greater than the WER of the second layer.

14. The substrate processing method according to claim 13, wherein applying plasma under the second processing condition to the first layer and the second layer so as to reduce a difference between the WER of the first layer and the WER of the second layer.

15. The substrate processing method according to claim 1, further comprising: purging plasma products under a second processing condition.

16. A substrate processing method, comprising: forming a first layer; applying a first plasma to the first layer to change a property of a portion of the first layer; forming a second layer on the first layer; applying a second plasma to the first layer and the second layer to change properties of respective portions of the first layer and the second layer; and applying a third plasma to the second layer to reduce a difference between the property of the portion of the first layer and the property of a portion of the second layer; using a first processing condition during the applying of the first plasma and the applying of the second plasma; wherein the forming of the first layer includes: supplying a first gas; purging the first gas; and supplying a second gas and plasma application to form the first layer; wherein, during the supplying of the second gas and the plasma application to form the first layer, a pressure in a reaction space is maintained at a first pressure, and during plasma application under the first processing condition, the pressure in the reaction space is maintained at a second pressure lower than the first pressure; wherein a power supplied during plasma application under the first processing condition is greater than a power supplied during the supplying of the second gas and the plasma application to form the first layer.

17. The substrate processing method according to claim 16, ​ using second process conditions different from the first process conditions during application of the third plasma.

18. The substrate processing method of claim 17, further comprising: purging the plasma product under second process conditions.

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