阅读说明：本技术 基底处理方法 (Substrate processing method ) 是由 姜熙成 闵允基 林完奎 吴锡宰 曹成日 于 2020-09-22 设计创作，主要内容包括：一种基底处理方法,其能够实现形成在阶梯结构上的薄膜的整个厚度范围中的均匀的蚀刻选择性,该方法包括：通过执行多个循环而在基底上形成薄膜,该循环包括形成至少一层以及在第一处理条件下将等离子体施加到该至少一层；以及在不同于第一处理条件的第二处理条件下将等离子体施加到薄膜。(A substrate processing method capable of achieving uniform etching selectivity in the entire thickness range of a thin film formed on a stepped structure, comprising: 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 first processing conditions; and applying the plasma to the thin film under a second process condition different from the first process condition.)

1. A method of processing a substrate, comprising:

forming a thin 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 thin film under a second process condition different from the first process condition.

2. The substrate processing method according to claim 1,

the atmosphere is set such that plasma ions have directionality during the application of plasma under the first processing condition and the application of plasma under the second processing condition.

3. The substrate processing method according to claim 1,

wherein a bonding structure of a portion of the thin film changes during the application of plasma under the first processing conditions, and

the bonding structure of a portion of the thin film is further altered during the application of plasma under the second processing conditions.

4. The substrate processing method according to claim 3,

also included is an isotropic etching operation that is performed,

wherein during the isotropic etching operation, an etching selectivity between a portion of the thin film where the bonding structure is changed and the rest of the thin film is achieved.

5. The substrate processing method according to claim 3,

wherein 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, an

A portion of the thin film corresponds to a portion of the thin film formed on the upper surface and the lower surface.

6. The substrate processing method according to claim 5,

wherein repetition of the cycle results in a difference between a first bonded structure of a first portion of the film adjacent to the stair-step structure and a second bonded structure of a second portion of the film distal from the stair-step structure, and

a difference between the first bonded structure of the first portion and the second bonded structure of the second portion is reduced during the applying of plasma under the second processing condition.

7. The substrate processing method according to claim 5,

also included is an isotropic etching operation that is performed,

wherein after the isotropic etching operation, the thin films on the upper and lower surfaces of the stepped structure are removed and the thin films on the side surfaces of the stepped structure remain.

8. The substrate processing method according to claim 1,

during the application of the plasma under the second process conditions, a hydrogen-containing gas is supplied.

9. The substrate processing method according to claim 1,

wherein forming the at least one layer comprises:

supplying a first gas;

purging the first gas; and

a second gas is supplied and a plasma is applied to form a first layer.

10. The substrate processing method according to claim 9,

wherein during the supplying of the second gas and the applying of the plasma to form the first layer, the pressure in the reaction space is maintained at a first pressure, and

maintaining a pressure in the reaction space at a second pressure lower than the first pressure during the applying of the plasma under the first process conditions.

11. The substrate processing method according to claim 9,

wherein the power supplied during the application of the plasma under the first processing conditions is greater than the power supplied during the supply of the second gas and the application of the plasma to form the first layer.

12. The substrate processing method according to claim 9,

wherein the first gas is supplied during the application of the plasma at the second process condition different from the first process condition.

13. The substrate processing method according to claim 9,

wherein supplying the first gas, purging the first gas, and supplying the second gas and applying plasma to form a first layer are performed a plurality of times during a first cycle.

14. The substrate processing method according to claim 13,

wherein, during a first cycle, plasma under the first processing conditions is applied to the first layer such that the WER of a portion of the first layer is increased due to an ion bombardment effect of plasma ions.

15. The substrate processing method according to claim 14,

wherein a second layer is formed on the first layer during a second cycle subsequent to the first cycle,

wherein forming the second layer comprises:

supplying a first gas;

purging the first gas; and

a second gas is supplied and a plasma is applied to form the second layer.

16. The substrate processing method according to claim 15,

wherein, during a second cycle, plasma under the first processing 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 is 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.

17. The substrate processing method according to claim 16,

wherein the plasma at the second processing condition is applied to the first layer and the second layer, thereby reducing a difference between a WER of the first layer and a WER of the second layer.

18. A method of processing a substrate, comprising: forming a first layer;

applying a first plasma to the first layer to alter a characteristic 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 alter a characteristic 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 a characteristic of a portion of the first layer and a characteristic of a portion of the second layer.

19. The substrate processing method according to claim 18,

wherein first processing conditions are used during the applying of the first plasma and the applying of the second plasma, an

Using a second processing condition different from the first processing condition during the applying of the third plasma.

20. A method of processing a substrate, comprising:

forming a thin film on a substrate by performing a cycle including supplying a first gas to the substrate and supplying a second gas reactive with the first gas a plurality of times, wherein a WER of a first portion of the thin layer adjacent to the substrate is higher than a WER of a second portion of the thin layer distant from the substrate due to repetition of the cycle; and

reducing a difference between the WER of the first portion and the WER of the second portion.

21. The substrate processing method of claim 1, further comprising:

the plasma products are purged under second process conditions.

Technical Field

One or more embodiments relate to a substrate processing method, and more particularly, to a substrate processing method that may improve an etch selectivity of a thin film formed on a stepped structure.

Background

With the miniaturization and three-dimensionality of semiconductor pattern structures, new thin film deposition techniques that can simplify the process are increasingly needed. For example, the 3D NAND flash memory device has a vertically stacked gate structure and an electrode wiring structure. In order to interconnect these structures, a technique of selectively removing the film deposited on the stepped structure to form a pad structure is required.

In order to selectively remove the film deposited on the stepped structure, a film is deposited on the stepped structure through a plasma process, and then the film is wet-etched to remove side films of the stepped structure, thereby leaving upper and lower films of the stepped structure. However, a method of removing the upper and lower films of the stepped structure and leaving the side films of the stepped structure may also be used.

The method can be implemented by controlling the plasma to be applied and adjusting the characteristics of the upper and lower films or the side films of the stepped structure. For example, the side film may be removed during etching by making the upper film and the lower film harder than the side film in a direction perpendicular to a traveling direction of radicals using linearity of radicals. In contrast, by increasing the intensity of the plasma to enhance the ion bombardment, the combined structure of the upper and lower films, not the side films, can be weakened, thereby removing the upper and lower films during etching.

This process can be accomplished by varying the plasma application conditions. For example, below a certain plasma power or plasma density, film densification may dominate on the film surface perpendicular to the direction of radical travel. In contrast, above a certain plasma power or plasma density, the film bond structure may be weakened on the film surface perpendicular to the direction of radical travel.

Disclosure of Invention

One or more embodiments include a substrate processing method that may improve an etch selectivity of a thin film by achieving a uniform etch selectivity over an entire thickness of the thin film formed on a stepped structure.

Additional aspects will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the presented embodiments of the disclosure.

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 a plasma to the at least one layer under first processing conditions for the layer; and applying the plasma to the thin film under a second process condition different from the first process condition.

According to an example of the substrate processing method, the atmosphere may be set such that plasma ions have directionality during application of plasma under the first processing condition and during application of plasma under the second processing condition.

According to another example of the substrate processing method, a bonding structure of a portion of the thin film may be changed during the plasma is applied under the first processing condition, and the bonding structure of the portion of the thin film may be further changed during the plasma is applied under the second processing condition.

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, an etching selectivity between a portion of the thin film where the bonding structure is changed and the remaining portion of the thin film is achieved.

According to another example of the substrate processing method, the 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 surface and the lower surface, and the portion of the thin film corresponds to a portion of the thin film formed on the upper surface and the lower surface.

According to another example of the substrate processing method, the repetition of the above-described cycle causes a difference between a first bonding structure of a first portion of the thin film adjacent to the stepped structure and a second bonding structure of a second portion of the thin film distant 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 may be reduced during the plasma is applied under the second processing condition.

According to another example of the substrate processing method, the substrate processing method may further include an isotropic etching operation. After the isotropic etching operation, the thin films on the upper and lower surfaces of the stepped structure may be removed, and the thin films on the side surfaces of the stepped structure may remain.

According to another example of the substrate treating method, during the plasma application under the second treating condition, a hydrogen-containing gas may be supplied.

According to another example of the substrate processing method, the forming of the 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.

According to another example of the substrate processing method, the pressure in the reaction space may be maintained at a first pressure during the supplying of the second gas and the applying of the plasma to form the first layer, and the pressure in the reaction space may be maintained at a second pressure lower than the first pressure during the applying of the plasma under the first processing condition.

According to another example of the substrate processing method, the power supplied during the applying of the plasma under the first processing condition is larger than the power supplied during the supplying of the second gas and the applying of the plasma to form the first layer.

According to another example of the substrate processing method, the first gas may be supplied during the plasma application under a second processing condition different from the first processing condition.

According to another example of the substrate processing method, the supplying the first gas, the purging the first gas, and the supplying the second gas and the applying the plasma to form the second layer may be performed a plurality of times during the first cycle.

According to another example of the substrate processing method, during the first cycle, plasma under the first processing condition is applied to the first layer so that WER of a portion of the first layer can be increased due to an ion bombardment effect of plasma ions.

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

According to another example of the substrate processing method, during the second cycle, the plasma under the first processing condition is applied to the second layer and the first layer under the second layer, so that a WER of a portion of the first layer and a portion of the second layer may be increased due to an ion bombardment effect of plasma ions, wherein the WER of the first layer may be greater than the WER of the second layer.

According to another example of the substrate processing method, plasma of the second processing condition is applied to the first layer and the second layer, so that a difference between a WER of the first layer and a WER of the second layer can be reduced.

According to one or more embodiments, a substrate processing method includes: forming a first layer; applying a first plasma to the first layer to alter a characteristic 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 alter a characteristic 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 characteristic of the portion of the first layer and the characteristic of the portion of the second layer.

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

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

Drawings

The above and other aspects, features and advantages of particular embodiments of the present disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a flow diagram of a method of processing a substrate according to an embodiment;

FIG. 2 is a diagram of a substrate processing method according to an embodiment;

FIG. 3 is a diagram of a substrate processing method according to an embodiment;

FIG. 4 is a diagram of a substrate processing apparatus that performs a substrate processing method;

FIG. 5 is a view of a thin film formed on a stair step structure and the film remaining after isotropic etching;

FIG. 6 is a diagram of a substrate processing method according to an embodiment;

fig. 7 is a graph showing a change in wet etching rate of a thin film;

fig. 8 is a diagram of a state in which a thin film formed on a stepped structure remains after isotropic etching;

FIG. 9 is a diagram of a substrate processing method according to an embodiment;

FIG. 10 is a graph illustrating etch characteristics of a thin film after processing according to the present disclosure;

FIG. 11 is a view showing etching selectivity of a thin film obtained according to different substrate processing methods;

fig. 12 is a diagram of a substrate processing method according to an embodiment;

fig. 13 is a diagram of a substrate processing method according to an embodiment;

fig. 14 is a diagram of a substrate processing method according to an embodiment;

fig. 15 is a view of a state in which a thin film formed by the above-described substrate processing method remains after isotropic etching;

FIG. 16 illustrates a substrate processing method according to an embodiment of the present disclosure; and

fig. 17A and 17B illustrate the extent of wet etching of a thin film on the sidewalls of a pattern structure with or without the presence of plasma purging according to examples of the present disclosure.

Detailed Description

Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. In this regard, the present embodiments may have different forms and should not be construed as limited to the description set forth herein. Accordingly, the embodiments are described below to explain aspects of the present specification by referring to the figures only. 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 a list of elements, the entire list of elements is modified and individual elements of the list are not modified.

It will be understood that, although the terms "first," "second," etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are not intended to denote any order, quantity, or importance, but rather are used to distinguish one element, region, layer, and/or section from another element, region, layer, and/or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the embodiments.

In this specification, the term "gas" may include vaporized solids and/or liquids, and may include a single gas or a mixture of gases. 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 as a mixed gas, or may be introduced separately 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 diluent gases such as reactive gases and inert gases. The reactant gas and the diluent gas may be mixed or introduced separately into the reaction space. The precursor may include two or more precursors, and the reaction gas may include two or more reaction gases. The precursor is a gas that is chemisorbed onto the substrate and generally contains a metalloid (metalloid) or a metal element that constitutes the main structure of the matrix of the dielectric film, and the reaction gas for deposition is a gas that reacts with the precursor chemisorbed onto the substrate when excited to fix an atomic layer or monolayer on the substrate. The term "chemisorption" may refer to chemically saturated adsorption. Gases other than the process gas, i.e., gases introduced without passing through the showerhead, may be used to seal the reaction space, and may include a sealing gas such as an inert gas. In some embodiments, the term "film" may refer to a layer that extends continuously in a direction perpendicular to the thickness direction without substantial pores to cover the entire target or associated surface, or 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 having a film or non-film structure of any thickness formed on a surface. A film or layer may comprise a discrete single film or layer or a plurality of films or layers having certain properties, and the boundaries between adjacent films or layers may or may not be clear and may be set based on the physical, chemical, and/or some other property, formation process or sequence, and/or function or purpose of the adjacent films or layers.

In the present disclosure, the expression "comprising a Si — N bond" may be referred to as being characterized by a Si — N bond, which has a main skeleton composed mainly of Si — N bonds and/or has a substituent composed mainly of 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).

In the present disclosure, the expression "the same material" should be interpreted to mean that the main components (constituents) are the same. 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 Si₂N，SiN，Si₃N₄And Si₂N₃And the second layer may also be selected from the above group, but its specific film quality may be different from that of the first layer.

Additionally, in the present disclosure, according to the operable ranges may be determined based on conventional work, any two variables may constitute the operable ranges of the variables, and any indicated range may include or exclude endpoints. Additionally, the values of any indicated variable may refer to exact or approximate values (whether or not they are indicated as "about"), may include equivalent terms, and may refer to average, median, representative, majority, and the like.

In the present disclosure, in the case where conditions and/or structures are not specified, those of ordinary skill in the art can easily provide these conditions and/or structures according to routine experiments in light of the present disclosure. In all described embodiments, any components used in the embodiments may be replaced with their equivalents for the intended purpose, including components explicitly, necessarily or essentially described herein, and furthermore, the present disclosure may be similarly applied to the apparatuses and methods.

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In the drawings, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Accordingly, embodiments of the present disclosure should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing.

FIG. 1 is a flow chart of a method of processing a substrate according to an embodiment of the invention.

Referring to fig. 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 as a set cycle a plurality of times, and a thin film may be formed on the substrate by repeating. The substrate processing method may further include an operation S150 of applying plasma under a second process condition different from the first process condition.

During operation S110 of forming at least one layer, a thin film may be formed on the stepped structure. That is, the thin film may be formed on a stepped structure having an upper surface, a lower surface, and a side surface between the upper surface and the lower surface. The step structure may be a structure having a high aspect ratio, and the aspect ratio may be, for example, greater than or equal to the width: height 1: 10. to form a conformal thin film over such high aspect ratio step structures, an Atomic Layer Deposition (ALD) process may be used. In particular, a plasma atomic layer deposition Process (PEALD) may be used.

During operation S110 of forming at least one layer, the atmosphere may be set such that the mean free path of the plasma ions is reduced and the plasma ions are not directional (i.e., such that the random motion of the plasma ions is increased). Such an atmosphere may facilitate the formation of a conformal thin film on a step structure having a high aspect ratio. To achieve the above atmosphere, a high pressure atmosphere (e.g., 10to 20Torr) may be formed. In another embodiment, to achieve the above atmosphere, a low power atmosphere (e.g., 200W to 500W) may be formed. In another embodiment, to achieve the above atmosphere, a high temperature atmosphere may be formed.

During operation S110 of forming at least one layer, the layer may be formed using plasma. For example, operation S110 may include supplying a first gas, purging the first gas, and supplying a second gas and applying plasma to form a first layer. By applying plasma, the second gas may be excited to become reactive, and the reactive second gas may react with the first gas to form the first layer.

The first gas may include a material that is chemisorbed on the substrate as a source gas. The second gas may include a material that is reactive with the first gas, particularly a material that is reactive with the first gas under a plasma atmosphere. In an alternative embodiment, the supply of the second gas and the application of the plasma may be performed simultaneously. In another embodiment, the application of the plasma may be performed after the second gas is supplied.

Operation S110 of forming at least one layer may be performed a plurality of times (e.g., a cycles). In more detail, the group cycle GC including the operation S110 of forming at least one layer and the operation S120 of applying plasma under the first process condition may be performed a plurality of times. The operation S110 of forming at least one layer may be performed a plurality of times during one group cycle GC. Accordingly, during one cycle, the supplying of the first gas, the purging of the first gas, and the supplying of the second gas and the applying of the plasma to form the second layer, which are included in the operation S110 of forming at least one layer, may be performed a plurality of times.

After operation S110 of forming at least one layer, operation S120 of applying plasma under the first process condition is performed. The operation S120 of applying plasma under the first process condition may be performed for a certain time (e.g., b seconds). The bonding structure of a portion of at least one layer may be altered by applying plasma under first processing conditions. During operation S120 of applying plasma under the first process condition, plasma ions may be set to be directional. On the other hand, as described above, during operation S110 of forming at least one layer, the plasma ions may be set to have no directionality.

Directing the plasma ions may alter the bonding structure of a portion of the film. For example, in the case of forming a thin film on a stepped structure having a high aspect ratio, the directionality of plasma ions may be set to face the upper surface or the lower surface of the stepped structure. In this case, the plasma ions may change the bonding structure of the thin film formed on the upper surface or the lower surface of the stepped structure. In contrast, the directional plasma ions may not affect the bonding structure of the thin film formed on the side of the stepped structure.

As described above, in operation S110 of forming at least one layer, the pressure in the reaction space may be maintained at the first pressure (e.g., high pressure) while the second gas is supplied and the plasma is applied, so that the random movement of the reaction gas may be increased. In contrast, in operation S120 of applying the plasma under the first process condition, the pressure in the reaction space may be maintained at a second pressure (e.g., a low pressure) less than the first pressure such that the movement of the reaction gas is directional.

Further, in operation S110 of forming at least one layer, the power supplied during operation S110 may be maintained at a first power value (e.g., a low power value) such that the reaction gas is less affected by the power (i.e., the plasma ions become non-directional). In contrast, in operation S120 of applying the plasma under the first process condition, the power supplied during operation S120 may be maintained at a second power value (e.g., a high power value) higher than the first power value, so that the reaction gas is more affected by the power (i.e., the plasma ions become directional).

Operation S110 of forming at least one layer and operation S120 of applying plasma under the first process condition may be defined as one set of cycles GC, and the set of cycles GC may be repeatedly performed. In other words, the value of X is set to 1 before the group cycle GC is performed in operation S100, and the value of X is increased after the group cycle GC including operation S110 of forming at least one layer and operation S120 of applying plasma under the first process condition is performed in operation S140, and when the value of X reaches a certain value in operation S130, the group cycle GC is terminated and the subsequent operation is performed.

As a subsequent operation, operation S150 of applying plasma under the second process condition is performed. The operation S150 of applying the plasma under the second process condition may be performed for a specific time (e.g., y seconds). The bonding structure of a portion of the at least one layer may be further altered by applying the plasma under the second processing conditions. During operation S150 of applying plasma under the second process condition, plasma ions may be set to be directional.

For example, the plasma ions may be arranged to be directed towards at least one layer. In this case, since the plasma ions are incident at least toward the layer, the portion of the at least one layer where the bonding structure is changed will be the portions formed on the upper and lower surfaces of the pattern structure. When the power of the plasma is higher than the threshold value, portions formed on the upper and lower surfaces of the at least one layer will be weakened, and when the power of the plasma is lower than the threshold value, the portions formed on the upper and lower surfaces of the at least one layer will be densified.

The operation S120 of applying plasma under the first process condition and the operation S150 of applying plasma under the second process condition have in common that they change the bonding structure of the thin film. However, since the first and second process conditions are different, the thickness range of the thin film in which the bonding structure is changed by the first process condition is different from the thickness range of the thin film in which the bonding structure is changed by the second process condition.

In more detail, when a cycle including operation S110 of forming at least one layer and operation S120 of applying plasma under the first process condition is repeated, in the case of the initially formed layer (i.e., the first portion of the thin film adjacent to the stepped structure), the change of the bonding structure due to the plasma application may be accumulated. Meanwhile, in the case of a later-formed layer (i.e., a second portion of the thin film away from the stepped structure), only a small amount of plasma application (or one plasma application) is performed, and thus the variation in bonding structure may be relatively small.

To counteract this local difference in the bonding structure, a plasma under the second processing conditions may be applied. For example, the plasma under the second processing conditions may be applied to cause a change in the bonding structure of the second portion of the film distal from the stair step structure and not affect the bonding structure of the first portion of the film proximal to the stair step structure. By applying the plasma under the second processing condition, a difference between the bonding structure of the first portion and the bonding structure of the second portion can be reduced.

In one embodiment, the hydrogen-containing gas may be supplied during operation S150 of applying the plasma under the second process condition. By performing the plasma treatment using the hydrogen-containing gas, more Si — H bonds can be formed in the second portion of the thin film away from the step structure. Accordingly, the etching rate of the corresponding portion can be increased in the subsequent etching process.

In another embodiment, the same gas as that supplied in operation S150 of forming at least one layer may be supplied during operation S150 of applying plasma under the second process condition. 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 the step S110 of forming at least one layer. The first gas (e.g., source gas) may be supplied during operation S150 of applying plasma under the second process condition.

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

After operation S150 of applying plasma under the second process condition, operation S160 of performing isotropic etching on the thin film formed by performing a plurality of set cycles is performed. For example, wet etching of the thin film may be performed. For example, wet etching may 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 such wet etching is isotropic etching, such isotropic etching itself may not significantly affect selective etching of a thin film formed on the stepped structure.

During operation S160 of the isotropic etching, an etching selectivity between the portion of the thin film, the bonding structure of which is changed, and the remaining portion of the thin film may be achieved. In other words, by performing operation S120 of applying plasma under the first process condition and operation S150 of applying plasma under the second process condition, the bonding structure of a portion of the thin film on the stepped structure (thin films on the upper and lower surfaces of the stepped structure) is changed, so that a portion of the thin film may be removed while the other portion remains during isotropic etching. By removing a portion of the film on the step structure, the surface of the step structure can be exposed. Thus, selective etching of the thin film can be achieved by a subsequent etching process. Accordingly, a patterned thin film formed on a region of the stepped structure may be formed without a separate additional photolithography process.

According to an embodiment of the inventive concept, a combination of operation S120 of applying plasma under a first process condition and operation S150 of applying plasma under a second process condition different from the first process condition is utilized. By combining and applying plasmas having different process conditions, uniform etch selectivity can be achieved over the entire thickness range of a thin film formed on a stepped structure, as compared with the case where plasmas of only one process condition are applied.

When only operation S120 of applying plasma under the first process condition is performed, a region where plasma is applied a plurality of times appears as the cycle is repeated. Therefore, by applying the plasma a plurality of times, the etching selectivity is increased in the deep portion of the thin film, and the etching selectivity is relatively decreased in the surface of the thin film. In the case where the etching selectivity at the surface is low, since the thickness of the thin film needs to be deposited thicker than the target thickness in order to form the side film of an appropriate thickness, the productivity is lowered.

When only operation S150 of applying plasma under the second process condition is performed, high etch selectivity may be achieved by ion bombardment effect and/or penetration of reactive species (e.g., hydrogen ions) into the thin film. However, the probability of defects in the substrate is increased by the bombardment effect and penetration of reactive species. In order to prevent this, when the plasma power is reduced or the penetration force of the reactive substance is reduced, the following problems occur: the etch selectivity decreases at deep portions of the thin film (i.e., portions adjacent to the stacked structure and/or the substrate). As a result, in order to form a side film of an appropriate thickness, the thickness of the thin film needs to be deposited thicker than a target thickness, thereby reducing productivity.

By performing a combination of operation S120 of applying plasma under a first process condition and operation S150 of applying plasma under a second process condition different from the first process condition, their respective disadvantages can be compensated. In other words, by the combination, a significantly improved effect can be achieved as compared with the case where only the plasma applying process alone is performed.

The change in the bonding structure of the portion of the film caused by the plasma ions may be a weakening of the bonding structure or may be a densification of the bonding structure. Hereinafter, embodiments will be described in more detail on the premise of weakening the bonding structure.

The atmosphere may be set such that plasma ions have directionality during operation S120 of applying plasma under the first process condition and operation S150 of applying plasma under the second process condition. The bonding structure of a portion of the film can be weakened by the ion bombardment effect of the directed plasma ions.

In more detail, the plasma ions may have a direction 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. As a result, the thin films on the upper and lower surfaces of the stepped structure may be removed and the thin films on the side surfaces of the stepped structure may remain through the subsequent operation S160 of isotropic etching.

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

During the first set of cycles and after the sub-cycles, the plasma may be applied at the first processing conditions for a particular time. By applying plasma to the first layer at the first processing condition, a Wet Etching Rate (WER) of a portion of the first layer may be increased due to an ion bombardment effect of plasma ions.

This will end the first set of cycles and start the second set of cycles. During the second set of cycles, operation S110 of forming at least one layer may be performed to have a plurality of sub-cycles. A 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 the first gas, purging the first gas, and supplying the second gas and applying the plasma to form the second layer may be performed.

During the second set of cycles and after the sub-cycles for forming the second layer, the plasma may be applied under the first processing conditions for a specified time. By applying the plasma to the second layer under the first processing conditions, the WER of a portion of the second layer can be increased due to an ion bombardment effect of plasma ions. At the same time, the applied plasma may affect not only the second layer, but also the first layer below the second layer. Accordingly, the WER of a portion of the first layer may be further increased, and thus, the WER of the first layer may be greater than the WER of the second layer.

After the first set of cycles and the second set of cycles, a plasma under second processing conditions may be applied toward the first layer and the second layer. As described above, the second processing conditions may be different from the first processing conditions. In particular, the second processing conditions may be processing conditions that weaken the upper second layer but do not significantly affect the lower first layer. For example, the second processing conditions may produce a reactive species with low permeability, and the reactive species may weaken only the overlying second layer and not significantly affect the underlying first layer. As a result, by applying the plasma of the second treatment, the difference between the WER of the first layer and the WER of the second layer can be reduced.

Although it is described in this disclosure that the plasma at the second processing condition is applied after the second set of cycles, additional sets of cycles may be performed between the second set of cycles and the application of the plasma at the second processing condition. For example, the third set of loops may be performed after the second set of loops. During the third set of cycles, operation S110 of forming at least one layer may be performed to have a plurality of sub-cycles. A third layer formed during the third set of cycles will be formed on the first layer and the second layer.

Subsequently, plasma under the first process condition is applied to the third layer, and the WER of a portion (portions on the upper surface and the lower surface of the stepped structure) can be increased due to an ion bombardment effect of plasma ions (see fig. 6). As the cycle repeats, a first portion of the film (e.g., a first layer) adjacent to the substrate will have a higher WER than a second portion of the film (e.g., a second layer) distal to the substrate.

For the purpose of reducing the difference in WER, plasma application under the second process condition performed after the set cycle is performed. In other words, by repeating the group cycle, the plasma under the first process condition is repeatedly applied to increase the etch selectivity of the deep portion of the thin film, while the etch selectivity of the surface of the thin film is decreased. Therefore, the plasma under the second process condition is applied to solve the problem. By applying the plasma under the second process condition, the etching selectivity of the surface of the thin film can be increased, and thus uniform etching selectivity can be achieved regardless of the thickness (or depth) of the thin film.

Fig. 2 is a view of a substrate processing method according to an embodiment. The substrate processing method according to the embodiment may be a modification of the substrate processing method according to the above-described embodiment. Hereinafter, a repetitive description of the embodiments will not be given here.

According to an embodiment of the inventive concept, a substrate treating method may be proposed to increase the WER of films deposited on the upper and lower portions of the stepped structure and make the WER constant with time. For example, a first sub-step of uniformly depositing a hard and uniform thin film on the step structure, a second sub-step of performing plasma treatment to increase the etching selectivity of the thin film deposited on the side, upper and lower portions of the step structure, and the use of a hydrogen-containing gas (e.g., H) may be performed₂) A third substep of plasma treatment is carried out.

Referring to fig. 2, during the first substep (step 1), a hard and uniform SiN film is uniformly deposited on the stepped structure. For example, the SiN film may be deposited by plasma atomic layer deposition. The first substep (step 1) may be repeated a plurality of times, and a SiN film having a certain thickness may be formed. During the second substep (step 2), plasma treatment was performed for b seconds (seconds). The first and second substeps are grouped into a set of cycles and the deposited film is repeated multiple times (x cycles) depending on the desired thickness. In the first sub-step (step 1), a high process pressure and a low plasma power are applied to weaken the directionality (linearity) of the plasma reactive species 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 thin film deposited on the side, upper and lower portions of the stepped structure is increased by providing a low process pressure and a high plasma power to improve the directionality (linearity) of the plasma reactive species.

The third substep (step 3) is a plasma treatment step using a hydrogen-containing gas, which is held for y seconds (seconds). The low pressure and high plasma power are maintained so that H ions generated from the hydrogen-containing gas easily permeate into the film. H ions may form weak bonds or weak bonds with SiNTo form a Si-N bonding structure. Weakening the binding structure by H ions can maximize the effect at the surface directly subjected to plasma treatment. Here, H is kept low₂The flux to prevent H-ion accumulation (i.e., to prevent weakening of the thin film in the deep portion). For example, in the third substep (step 3), H can be performed under the condition of 100sccm or less₂And (4) flow rate. The third substep (step 3) is a step of adjusting the etching selectivity at the surface of the deposited film to be similar to the etching selectivity at the deep portion of the deposited film.

In an alternative embodiment, in the plasma treatment of the third substep (step 3), other gases that easily permeate into the film may be used in addition to the hydrogen-containing gas. Gases such as He to Ar may be used. Wet etching is then performed to leave the SiN film on the side walls, and to remove the SiN film on the upper and lower walls.

Fig. 3 is a view of a substrate processing method according to an embodiment. FIG. 4 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 modification of the substrate processing method according to the above-described embodiment. Hereinafter, a repetitive description of the embodiments will not be given here.

Referring to fig. 4, the substrate treating apparatus may include at least one reactor. An upper electrode (e.g., a showerhead) connected to the RF generator and a lower electrode disposed opposite the upper electrode may be disposed in the reactor. A substrate may be loaded on a 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.

The layer formed on the substrate using the substrate processing apparatus may be a silicon nitride layer. A plasma atomic layer deposition (PEALD) process may be used to form the silicon nitride layer. As the Si source, dichlorosilane (SiH) can be used₂Cl₂) Aminosilane or iodosilane. As the nitrogen source, nitrogen gas may be used. Nitrogen gas, which reacts with the physisorbed silicon source on the substrate when activated by the plasma, but does not react with the silicon source when not activated by the plasma, may be used as a purge gas.

Referring to fig. 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 may be repeated a cycles and b cycles, respectively. These sub-steps may be included in a group loop, which may be repeated. The first substep (step 1) is a step of uniformly depositing a SiN film on the pattern structure, and the second substep (step 2) is a plasma processing step.

During the second substep (step 2), the bonding structure of the SiN film deposited on the upper surface of the pattern structure in the direction perpendicular to the traveling direction of the radicals may be weakened. Therefore, in the second substep (step 2), in order to enhance the plasma ion bombardment effect, an atmosphere having a lower process pressure and a higher plasma power may be provided as compared with the first substep (step 1). After the group cycle, at 100: wet etching on the substrate was performed in a 1-Diluted Hydrogen Fluoride (DHF) solution, with the result that the SiN film deposited on the upper surface of the pattern structure was removed and the SiN film deposited on the side surface of the pattern remained.

Meanwhile, 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 surface of the stepped structure is simultaneously etched. However, the etching rate of the SiN film on the upper surface is high, and as a result, the SiN film remains on the side surface. That is, in order to achieve a SiN film on the sidewalls of a desired thickness, 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 pattern structure is fast, the SiN film on the sidewalls can be realized with the same thickness even if the SiN film having a smaller thickness is formed during deposition. This will save processing time and speed up substrate processing per hour. Fig. 5 shows such a process, in which fig. 5(a) shows a SiN film formed on the stepped structure, and fig. 5(b) shows a SiN film remaining on the sidewall of the stepped structure after wet etching.

Referring to fig. 5(a), a SiN film is deposited on the pattern structure with a uniform thickness (upper film d ═ side film c in fig. 5A). Since the bonding structure of the upper SiN film is broken by the second substep (step 2) of fig. 3, the upper SiN film d is etched faster than the side SiN film c during wet etching. The thickness on the side SiN film is also removed to some extent, but the etch rate of the side SiN film is slower than the etch rate of the upper SiN film. Therefore, only the side SiN film (a in fig. 5(b)) remains after the wet etching (see fig. 5 (b)). That is, in order to realize the side film a of a desired thickness, the additional film b needs to be formed in consideration of the etching rate of the upper film d.

In other words, the etching rate Ed of the upper film d and the etching rate Ec of the side film c determine the selectivity, and the faster the etching rate Ed on the upper surface, the better the selectivity. As shown in fig. 5, a film (a + b) thicker than the side film a of a desired thickness is deposited in consideration of the difference in the etching rate of the upper film d and the side film c.

Fig. 6 illustrates a substrate processing method according to the embodiment of fig. 3. Referring to fig. 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. Nitrogen plasma treatment is performed on each layer during one cycle (step 2). For ease of understanding, in the present embodiment, it is shown that three set cycles GC1, GC2, and GC3(x ═ 3) are performed, and the nitrogen plasma treatment (step 2) (b ═ 1) is performed only once for each layer.

In fig. 6, the nitrogen plasma treatment performed for each set cycle is indicated by an asterisk. The first marker GC1 shows nitrogen radicals applied during the set cycle of depositing the first layer a, the second marker GC2 shows nitrogen radicals applied during the set cycle of depositing the second layer b, and the third marker GC3 shows nitrogen radicals applied during the set cycle of depositing the third layer c.

For example, since the nitrogen plasma treatment is performed by applying a plasma power higher than the critical plasma power, the nitrogen radicals destroy the bonding structure of the SiN layer deposited on the upper surface of the pattern. Although nitrogen plasma was applied in the above experiment, the bonding structure of the film can be more easily broken by applying Ar plasma having large and heavy elements.

As shown in fig. 6, it should be noted that the plasma applied in the second sub-step (step 2), which is a plasma processing step, also affects the underlying film when each film is deposited. That is, in forming each layer, in the second sub-step (step 2) in the set cycle, the nitrogen plasma treatment is performed for only one cycle (b ═ 1), but the lower layer is further subjected to the plasma treatment. In other words, when the first layer a, the second layer b, and the third layer c are sequentially deposited, the first layer a adjacent to the pattern structure is subjected to the plasma treatment three times, the second layer b on the first layer a is subjected to the plasma treatment two times, and the third layer c distant from the pattern structure is subjected to the plasma treatment one time. This means that the etching characteristics of the entire bulk film (a + b + c) are not uniform, and WER is higher toward the lower part of the thin film (Ea < Eb < Ec).

Fig. 7 shows a variation in wet etching rate in the SiN thin film, which is the bulk film according to fig. 6. The horizontal axis represents the change in etching time, and the vertical axis represents the change in etching rate according to the etching time. The relationship between the horizontal axis and the vertical axis corresponds to the change in the etching rate from the surface to the inside of the bulk film inside the film. As shown in the graph, the etching rate was not uniform from the surface to the deep portion of the SiN film. That is, it can be seen that the WER is small at the surface portion of the SiN thin film to which less plasma is applied, and the WER is large at the deep portion of the SiN thin film to which a large amount of plasma is applied by repeating the group cycle.

When the wet etching characteristics of the bulk film are not uniform, the selectivity between the upper surface and the side surface is reduced. For example, when the etching rate of the thin film on the upper surface is small at the initial stage of the wet etching process after the deposition process, the thin film on the side surface is etched as much as the thin film on the upper surface. In contrast, when the etching rate of the deep portion of the thin film is small in the post wet etching process after the deposition process, the thin film on the side surface is etched as much as the deep portion of the thin film. As a result, as shown in fig. 8, when the thin film on the upper portion of the pattern structure is etched, only the thin film having the thickness e less than or equal to the desired thickness a remains on the side surface, and as a result, the selectivity between the upper thin film and the side thin film is lowered.

Therefore, in view of this problem, it is necessary to deposit a thin film to have a relatively thick thickness in a thin film forming operation. This means that increased source and gas consumption increases the cost of ownership (COO) of the device and reduces the substrate flux per unit time.

Fig. 9 is a view of a substrate processing method according to an embodiment. The substrate processing method according to the embodiment may be a modification of the substrate processing method according to the above-described embodiment. Hereinafter, a repetitive description of the embodiments will not be given here.

Referring to fig. 9, disclosed is a substrate processing method capable of improving selectivity of a bulk film by making an etching rate of the bulk film uniform over the entire thickness thereof. The substrate processing method may be performed in a direct plasma deposition apparatus composed of an upper electrode and a lower electrode, as shown in fig. 4.

In the embodiment shown in fig. 9, a third substep (step 3) for performing a plasma post-treatment is added as compared to the embodiment of fig. 3. First, two substeps (step 1 and step 2) are repeated several times. That is, the first substep (step 1) repeats a cycles, and the second substep (step 2) repeats b cycles. Then, a group loop is executed so that the repetition is repeated several times (x loop repetitions). After the group step is completed, a third sub-step (step 3) for post-plasma processing is performed. The post plasma treatment may be repeated several times (e.g., y cycles). Each step will be described in more detail below.

1. First substep (step 1): conformal deposition

As a first substep, this step is a step of depositing a SiN film on the pattern. Since the SiN film is deposited with a uniform thickness, the SiN film deposited on the upper and side portions of the pattern has the same thickness. A source gas of the halide series (e.g., Dichlorosilane (DCS)) or aminosilane or iodosilane series may be used as the silicon source, while nitrogen may be used as the nitrogen source. When activated with plasma, nitrogen reacts with the silicon source to become a component of the film, but when not activated with plasma, nitrogen can be used as a purge gas without reacting with the silicon source.

During the first sub-step, a SiN film is uniformly applied on the pattern structure while alternately supplying the source gas, the reactor gas, and the plasma by the PEALD method and repeating several times (a cycles). The plasma power is attenuated to allow radicals to be supplied to the inside of the pattern. The plasma power is from 200 watts to 900 watts, preferably 500 watts.

In addition, the linearity of the radicals is weakened by increasing the process pressure, thereby allowing more radicals to be supplied to the pattern side surface than the pattern bottom surface, thereby promoting the formation of the SiN film on the side portion. During this step, a process pressure of about 10Torr to about 20Torr is maintained.

2. Second substep (step 2): cyclic plasma treatment

As a second substep, this step is a step of performing nitrogen plasma treatment on the SiN film deposited on the pattern. In particular, this step is intended to increase the etching 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 break the bonded structure of the film on the upper surface of the pattern structure in a direction perpendicular to the radical proceeding direction, so that the etching rate of the thin film on the upper portion is higher than that on the side portion.

In the present disclosure, although nitrogen gas having the same composition as that of the film is used, a heavier elemental Ar gas may be used to more easily destroy the bonding structure of the film. In this step, the 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 substep (step 1) to enhance radical linearity and ion bombardment effects.

In addition, in order to enhance ion bombardment on the upper and lower surfaces, not the side of the pattern, the processing pressure is set lower than that of the first substep (step 1). In the present disclosure, the plasma treatment is conducted at a process pressure of about 1Torr to about 5Torr, preferably about 3 Torr. This step is also repeated several times (b cycles). In addition, the set step of combining the first sub-step and the second sub-step is repeated several times (x cycles).

3. Third substep (step 3): post plasma treatment

This step is to solve the problem of non-uniformity of wet etching characteristics in the SiN film. In this step, hydrogen gas is added to activate a mixed gas of nitrogen and hydrogen gas by RF power. In order to promote the penetration of radicals into the film on the upper and lower surfaces of the pattern, the process pressure is lower than the deposition step (step 1) and the plasma power is higher than the deposition step (step 1). This step is performed at a plasma power of 700 to 1000 w, preferably 700 w, higher than that of the deposition step (step 1) to enhance radical linearity and ion bombardment effect.

In addition, the process pressure is set lower than the deposition step (step 1) to enhance ion bombardment on the upper and lower surfaces, not the pattern sides. In the present disclosure, the plasma treatment is conducted at a process pressure of about 1Torr to about 5Torr, preferably about 3 Torr. The hydrogen radicals form a weak bond with the SiN film or a bond structure weakening the SiN film, and the weakening effect of the hydrogen radicals on the bond structure is maximized on the surface directly subjected to plasma treatment. Therefore, the etching resistance of the film surface may be weakened.

In addition, by supplying nitrogen radicals together, ion bombardment of the SiN thin films on the upper and lower surfaces and the resulting weakening of the bonding structure can be enhanced. In the present disclosure, helium may be used, although hydrogen, which is smaller and lighter than other elements, is used. In another embodiment, only hydrogen may be supplied without supplying nitrogen.

Table 1 below shows exemplary experimental conditions applied for each step.

TABLE 1

By adopting the process conditions shown in table 1 above, the etching selectivity between films deposited on the upper surface and the side surface of the pattern when depositing a thin film on the pattern structure can be improved. In addition, by the process of depositing a uniform film on the pattern by the PEALD method (first sub-step (step 1)), the process of breaking the bonding structure of the film on the upper surface of the pattern (second sub-step (step 2)), and the process of achieving uniform etching characteristics and high etching rate (third sub-step (step 3)), higher etching selectivity and efficiency can be achieved for the RTS process as compared with the conventional art.

Fig. 10 is a graph illustrating the etching characteristics of a thin film after processing according to the present disclosure. As shown in fig. 10, when the conditions according to the present disclosure are applied, that is, when the first to third substeps (step 1+ step 2+ step 3) are performed, the WER is constant regardless of time. That is, a constant WER can be ensured regardless of the position in the SiN film.

Meanwhile, in the case of the embodiment of the first and third substeps (step 1+ step 3), it can be seen that hydrogen radicals (H) are supplied in spite of the hydrogen radicals (H) supplied during the third substep₂Post plasma treatment) is effective in breaking the bonding structure of the film surface, but the bonding structure of the deep portion of the film is not changed, so that the WER is decreased with time.

In the case of the embodiment of the first and second substeps (step 1+ step 2), it can be seen that, despite the nitrogen radicals (N) supplied during the second substep₂Cyclic plasma treatment) is effective in destroying the bonding structure of the deep portion of the thin film, but the bonding structure of the surface of the thin film is not changed, so that the WER is low at the start of etching, which lowers the etching selectivity.

Thus, according to embodiments of the inventive concept, by combining the ion bombardment effect (N) caused by nitrogen radicals₂Cyclic plasma treatment) and weakening of the etching resistance of the film surface by hydrogen radicals (post plasma treatment), the etching rate can be further improved by further weakening the etching resistance over the entire thickness of the upper film.

TABLE 2

Table 2 shows the results of the etch selectivity of the SiN film in the embodiment of fig. 10 for a wet etching time of 80 seconds. Etching is performed in a 100: 1DHF solution. According to FIG. 10 and Table 2 above, with use of nitrogen radicalsCyclic plasma treatment (N)₂Cyclic plasma treatment) 6.3 compared to the results according to the present disclosure increased to 21.5, thereby increasing the selectivity by a factor of 3.4 or more. I.e. except for cyclic plasma treatment with nitrogen radicals (N)₂Cyclic plasma treatment), the etching resistance of the film surface on the pattern structure is weakened by additionally performing plasma treatment (Post PT) using a hydrogen mixed gas (Post plasma treatment), and then the upper surface film can be etched at a uniform and high etching rate. That is, a thicker film can be left on the side of the pattern structure, so that effective handling performance can be achieved.

Fig. 11 schematically shows the results of table 2 above. It can be seen that by performing the first to third substeps (step 1+ step 2+ step 3) according to the present disclosure, the etching selectivity is greatly improved (see fig. 11B). In the case where only the first substep and the second substep are performed, the side surface film remains below the desired thickness, while the entire upper surface film is etched (see fig. 11A). However, when the first to third substeps (step 1+ step 2+ step 3) are performed, a film of a desired thickness remains.

Fig. 12 is a view of a substrate processing method according to an embodiment. The substrate processing method according to the embodiment may be a modification of the substrate processing method according to the above-described embodiment. Hereinafter, a repetitive description of the embodiments will not be given here.

Referring to fig. 12, a source gas may be supplied during the third substep (step 3). In this step, a SiN film is further deposited by supplying source gases. However, since a high plasma power is supplied during the third substep, the ion bombardment effect becomes dominant and the density of the newly deposited SiN thin film on the upper surface is weakened. Meanwhile, the newly deposited SiN thin film on the side surface has a relatively weak ion bombardment effect and a relatively high density.

In addition, since a low pressure atmosphere is formed during the third substep, an ion bombardment effect is applied to the bottom surface of the pattern structure in addition to the upper surface. That is, since the density of the newly deposited SiN thin films on the top and bottom surfaces is weakened and the density of the SiN thin films on the side surfaces is relatively increased, the etching selectivity may be improved in a subsequent isotropic etching operation (e.g., a wet etching operation).

Fig. 13 is a view of a substrate processing method according to an embodiment. The substrate processing method according to the embodiment may be a modification of the substrate processing method according to the above-described embodiment. Hereinafter, a repetitive description of the embodiments will not be given here.

Referring to fig. 13, operation S310 of forming a first layer is performed. The first layer may be formed to have a uniform thickness over the pattern structure. The first layer may include a plurality of layers, and the plurality of layers may be formed by repeatedly performing a cycle of the atomic layer deposition process. For example, the first layer may be an insulating layer.

Thereafter, an operation S320 of changing a characteristic of a portion of the first layer is performed. For example, the bonding structure of a portion of the first layer may be altered by applying directional energy under first processing conditions. In more detail, the first plasma of the first process condition may be applied in a direction substantially perpendicular to the first layer formed on the upper and lower surfaces of the pattern structure, and a bonding structure of portions of the first layer formed on the upper and lower surfaces of the pattern structure may be changed due to the first plasma.

Thereafter, operation S330 of forming a second layer on the first layer is performed. In an example, at least one layer may be interposed between the first layer and the second layer. The second layer may be formed to have a uniform thickness on the first layer. The second layer may include a plurality of layers, and the plurality of layers may be formed by repeatedly performing a cycle of the atomic layer deposition process. For example, the second layer may be formed of the same material as the first layer.

Thereafter, operation S340 of changing characteristics of portions of the first layer and the second layer is performed. For example, the bonding structure of portions of the first and second layers may be altered by applying directional energy under first processing conditions. In more detail, the second plasma of the first process condition may be applied in a direction substantially perpendicular to the second layer formed on the upper and lower surfaces of the pattern structure, and a bonding structure of portions of the first layer formed on the upper and lower surfaces of the pattern structure and portions of the second layer formed on the upper and lower surfaces of the pattern structure may be changed due to the second plasma.

Thereafter, operation S350 of reducing a difference between the characteristics of the portion of the first layer and the characteristics of the portion of the second layer is performed. When the above characteristic changing operation is repeated, the lower layer repeatedly receives energy, resulting in a characteristic difference between the upper layer and the lower layer. 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. Accordingly, the additional operation S350 may be performed to reduce a difference between the characteristic of the portion of the first layer and the characteristic of the portion of the second layer.

As an example of the additional operation S350, energy (e.g., third plasma) may be applied in a direction substantially perpendicular to the second layer formed on the upper and lower surfaces of the pattern structure, and the energy may further change a bonding structure of portions of the second layer formed on the upper and lower surfaces of the pattern structure. In more detail, the bonding structure of a portion of the second layer may be altered by applying the orienting energy under the second processing conditions.

The second processing condition is different from the first processing condition used in the above-described characteristic changing operation, and in particular, the second processing condition may be set so as to affect only the bonding structure of the second layer without affecting the bonding structure of the first layer. That is, a first processing condition may be used during the application of the first plasma and the application of the second plasma, and a second processing condition different from the first processing condition may be used during the application of the third plasma.

By applying the third plasma using the second process condition, only the bonding structure of the upper second layer can be changed 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.

Fig. 14 is a view of a substrate processing method according to an embodiment. The substrate processing method according to the embodiment may be a modification of the substrate processing method according to the above-described embodiment. Hereinafter, a repetitive description of the embodiments will not be given here.

Referring to fig. 14, an operation S510 of repeating a cycle to form a thin film is performed. 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) onto the substrate and supplying a second gas (e.g., a reactant gas) reactive with the first gas.

During repeated cycles, energy may be applied. Due to the repeated application of energy, the WER of a first portion of the film adjacent to the substrate may be higher than the WER of a second portion of the film distal from the substrate. That is, in the thin film adjacent to the substrate, energy is repeatedly applied during the formation of the thin film, thereby improving WER. However, the film far from the substrate can be activated only a limited number of times in the latter half of the film formation, and thus the WER does not increase.

Accordingly, an additional operation S520 of canceling such a WER difference may be performed. That is, operation S520 of reducing the difference between the WER of the first portion and the WER of the second portion may be further performed. For example, by setting the processing conditions such that energy can be applied to a portion adjacent to the exposed surface of the thin film, we can be increased for a portion adjacent to the exposed surface of the thin film (i.e., the second portion). As a result, variation of the WER due to the position of the thin film caused by repetition of cycles may be reduced, and a uniform WER may be achieved over the entire thickness range of the thin film during the subsequent wet etching operation S530.

Fig. 15 shows the SiN film shape on the stepped structure according to the film etching rate of the above-described substrate processing method. Fig. 15(a) shows the shape of the thin film before the wet-etched state. A thin film of a certain thickness is uniformly deposited on the stepped structure.

Fig. 15(b) shows an example of depositing and wet-etching a thin film using the first and second substeps. Since the etching rate of the upper and lower portions of the stepped structure is low at the start of wet etching, it is necessary to increase the over-etching rate to remove the upper and lower films of the stepped structure, so that the films on the side surfaces of the stepped structure become thinner. Therefore, when a side film of a certain thickness is required, the deposition thickness of the film needs to be increased and the productivity is lowered.

Fig. 15(b) shows an example of depositing and wet-etching a thin film using the first and third substeps. The etching rate is high only at the start of wet etching, and as etching proceeds, the etching rate rapidly decreases and converges to a specific value. Therefore, the patterning process is possible only when the thickness of the side film is thin, and the thin film remains at the upper and lower portions of the stepped structure when the thickness of the side film is thick.

Fig. 15(d) illustrates an example of depositing and wet-etching a thin film using the first, second, and third sub-steps according to an embodiment of the inventive concept. 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 the side film loss. In addition, since the thickness of the side film remaining after the wet etching becomes large, the application to which the process can be applied can be expanded.

Fig. 16 is a diagram illustrating a substrate processing method according to an embodiment. The substrate processing method according to the embodiment may be a modification of the substrate processing method according to the above-described embodiment. Hereinafter, a repetitive description of the embodiments will not be given here.

Referring to fig. 16, the substrate processing method may include forming at least one layer (S110), applying plasma under first processing conditions (S120), applying plasma under second processing conditions different from the first processing conditions (S150), and purging the plasma under the second processing conditions (S155), followed by an isotropic etching operation (S160). Plasma purging, as used herein, refers to purging plasma products, such as plasma-generated ions or radicals. The plasma purge operation (S155) may correspond to step 18 of fig. 9.

By performing the plasma cleaning operation (S155) under the second process condition, the etching selectivity of the thin film formed on the pattern structure may be improved. In more detail, the operation of applying plasma (S150) is performed to change a binding structure of a portion of the thin film on the pattern structure and activate ions or radicals held between the pattern structures. By performing the operation of plasma purging (S155), the plasma products remaining between the pattern structures may be removed.

In some embodiments, under the second process condition, a hydrogen-containing gas may be provided during the application of the plasma. In this case, the hydrogen-containing gas may be removed from the reaction space during the plasma purge operation (S155) under the second process condition. The hydrogen weakens the bonding structure of the films on the pattern structures, but also provides hydrogen between the pattern structures and affects the films deposited on one side of the pattern structures to some extent. Residual hydrogen between these pattern structures may be an inhibiting factor in improving etch selectivity. Accordingly, by performing the plasma purge (S155) under the second process condition and by removing the hydrogen remaining between the pattern structures, the etching selectivity can be improved by minimizing the influence of the hydrogen gas on the thin film on one side of the pattern structure.

In some embodiments, the applying of the plasma at the second process condition (S150) and the plasma purging at the second process condition (S155) may be performed in one cycle. That is, one cycle including the operations (S150 and S155) may be repeated a plurality of times to form a thin film satisfying a specific condition.

Fig. 17 shows a wet etching degree of the thin film on the sidewall of the pattern structure according to the presence or absence of the above-described plasma purge under the second process condition (S155). Fig. 17a shows a case where there is no plasma purge operation, and fig. 17b shows a case where a plasma purge operation is added.

Referring to fig. 17a, a thin film is formed on the pattern structure without plasma purging. Since the wet etching was performed for 5 minutes without plasma cleaning after the plasma was processed under the second process condition, the thin films on the upper and lower portions of the pattern structure were removed, and the thickness of the thin film on the sidewall of the pattern structure was reduced from 135 a to 113 a. That is, it can be seen that the wet etching rate reaches 4.4 angstroms per minute.

On the other hand, in the case where the plasma purge operation is added in fig. 17b, it can be seen that the wet etching rate is low. After the thin film is formed on the pattern structure, plasma treatment is performed under a second treatment condition, and then plasma purging is performed. After 5 minutes of wet etching, the films on the upper and lower portions of the pattern structure were removed, and the thickness of the film on the sidewall of the pattern structure was reduced from 142 angstroms to 130 angstroms. That is, it can be seen that the wet etching rate reaches 2.4 angstroms per minute.

Therefore, hydrogen gas around the sidewalls between the pattern structures is removed by the purging operation, thereby minimizing the influence of the hydrogen gas on the sidewalls. As a result, weakening of the bonding structure of the thin film on the sidewall is prevented, and the technical effect of high etching selectivity can be achieved.

During the plasma purge under the second process condition (S155), nitrogen may be used as the purge gas. That is, plasma products such as ions and radicals can be purified by supplying and discharging nitrogen gas to and from the reaction space. In some embodiments, during the plasma purge at the second process condition (S155), the vacuum purge may be applied without a separate purge gas. In another embodiment, the nitrogen purge gas and the hydrogen gas may be supplied together during the plasma purge under the second process condition (S155). By supplying the nitrogen purge gas together with hydrogen gas, pressure fluctuation can be reduced, making the process more stable.

The following table 3 shows the wet etching rate of each portion of the pattern structure according to the presence or absence of the above plasma cleaning under the second process condition (S155)

When the purge operation is added in table 3 above, the etching rate is generally decreased as hydrogen is removed from the reaction space, but it can be seen that the etching selectivity between the film on the sidewall and the film on the upper surface of the pattern structure is significantly improved as compared to the case without the purge operation.

As described above, according to the present invention, there is a technical effect that the etching selectivity between the upper surface and the side surface of the pattern structure can be improved by adding the purging operation and removing the hydrogen gas remaining near the sidewall between the pattern structures in the hydrogen plasma processing operation.

It is to be understood that the embodiments described herein are to be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects in each embodiment should generally be considered as available for other similar features or aspects in other embodiments. Although one or more embodiments have been described with reference to the accompanying drawings, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.