Wet etching method for preventing under-cuts and mask structure used therefor

Abstract

Disclosed are a wet etching method for preventing under-cuts and a mask structure used therefor. A wet etching method according to an embodiment of the present invention may include a step of wet-etching a target etching area by using a first mask, which defines the target etching area of a target etching object, and a second mask arranged on the edge region of the target etching area.

Description

Wet etching method for preventing undercut and mask structure used therefor

[0001] The following examples relate to a wet etching method for preventing undercut and a mask structure used therein.

[0002] The most common techniques for manufacturing membranes utilize photolithography and wet etching. These techniques involve lithography to create a pattern for the desired membrane area, then selectively removing the area using wet etching.

[0003] However, in the final stage of the etching process for membrane production, an undercut may occur in the lateral direction, causing the previously deposited thin film to fall off, which may cause a disadvantage of acting as a source of contamination for the membrane.

[0004] These shortcomings can cause problems of quality degradation during performance evaluation, and therefore, a technology needs to be proposed to resolve these shortcomings and problems.

[0005]

[0006] One embodiment proposes a wet etching method and a mask structure used therein to prevent undercuts that act as a source of contamination in a membrane, in order to solve the problem of quality degradation during performance evaluation.

[0007] At this time, one embodiment proposes a wet etching method and a mask structure used therein that prevents a plateau caused by stress concentration and etching non-uniformity in an etching process.

[0008] However, the technical problems to be solved by the present invention are not limited to the above problems, and can be expanded in various ways without departing from the technical spirit and scope of the present invention.

[0009] According to one embodiment, the wet etching method may include a step of performing wet etching on an etching target region using a first mask defining an etching target region of an etching object and a second mask disposed at an edge region of the etching target region.

[0010] According to one aspect, the second mask may be characterized in that it is disposed in the edge region determined based on the penetration distance of an undercut that occurs when wet etching is performed on the etching target object on which only the first mask is disposed.

[0011] According to another aspect, the second mask may be formed of a material that reduces surface roughness in the edge region or has reactivity with an etching solution used in the wet etching to reduce an etching rate in the edge region of the etching target region.

[0012] According to another aspect, the second mask may be characterized in that it is formed of a material having an etching rate lower than that of the etching target and a higher etching rate than that of the first mask.

[0013] According to another aspect, the second mask may be characterized in that it is formed of a material that is soluble in an etching solution used for the wet etching or can be removed through a reaction with the etching solution.

[0014] According to another aspect, the second mask may be characterized by having a protruding shape protruding from at least one vertex on the inner and outer surfaces corresponding to the vertex of the etching target area.

[0015] According to another aspect, the protruding shape may be characterized by having a shape that minimizes undercut occurring at the vertex of the etching target area.

[0016] According to another aspect, the step of performing the wet etching may be characterized by including the step of disposing the first mask on an area remaining on one side of the etching target area excluding the etching target area based on the etching target area; the step of disposing the second mask on an edge area of ​​the etching target area; and the step of performing wet etching on the etching target area on which the first mask and the second mask are disposed.

[0017] According to one embodiment, a mask structure used in wet etching may include a first mask defining an etching target area of ​​an etching object; and a second mask disposed in an edge area of ​​the etching target area.

[0018] According to one aspect, the second mask may be characterized in that it is disposed in the edge region determined based on the penetration distance of an undercut that occurs when wet etching is performed on the etching target object on which only the first mask is disposed.

[0019] According to another aspect, the second mask may be formed of a material that reduces surface roughness in the edge region or has reactivity with an etching solution used in the wet etching to reduce an etching rate in the edge region of the etching target region.

[0020] According to another aspect, the second mask may be characterized in that it is formed of a material having an etching rate lower than that of the etching target and a higher etching rate than that of the first mask.

[0021] According to another aspect, the second mask may be characterized in that it is formed of a material that is soluble in an etching solution used for the wet etching or can be removed through a reaction with the etching solution.

[0022] According to another aspect, the second mask may be characterized by having a protruding shape protruding from at least one vertex on the inner and outer surfaces corresponding to the vertex of the etching target area.

[0023] According to another aspect, the first mask and the second mask may be characterized in that they are used simultaneously in a single wet etching process.

[0024] One embodiment proposes a wet etching method and a mask structure used therefor that prevents undercuts that act as a source of contamination in a membrane, thereby achieving a technical effect that solves the problem of quality deterioration during performance evaluation.

[0025] At this time, one embodiment can propose a wet etching method and a mask structure used therein that prevents a plateau caused by stress concentration and etching non-uniformity in an etching process.

[0026] However, the effects of the present invention are not limited to the above effects, and can be expanded in various ways without departing from the technical spirit and scope of the present invention.

[0027] FIG. 1 is a flow chart illustrating a wet etching method according to one embodiment.

[0028] Figures 2a to 2c are plan views illustrating a wet etching method according to one embodiment.

[0029] Figures 3a to 3c are cross-sectional views illustrating a wet etching method according to one embodiment.

[0030] Figures 4a to 4d are plan views illustrating the protruding shape of the second mask according to one embodiment.

[0031] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. However, the present invention is not limited or restricted by these embodiments. In addition, the same reference numerals in each drawing represent the same components.

[0032] In addition, the terminology used in this specification is a term used to appropriately express the preferred embodiments of the present invention, and this may vary depending on the intention of the viewer or operator, or the customs of the field to which the present invention belongs. Therefore, the definition of these terms should be determined based on the contents of this specification. For example, in this specification, the singular also includes the plural unless specifically stated in the phrase. In addition, the terms "comprises" and / or "comprising" as used in this specification do not exclude the presence or addition of one or more other components, steps, operations, and / or elements. In addition, although the terms first, second, etc. are used in this specification to describe various regions, directions, shapes, etc., these regions, directions, and shapes should not be limited by these terms. These terms are only used to distinguish a certain region, direction, or shape from another region, direction, or shape. Therefore, a part referred to as a first part in one embodiment may be referred to as a second part in another embodiment.

[0033] It should also be understood that the various embodiments of the present invention, while different, are not necessarily mutually exclusive. For example, specific shapes, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the present invention. Furthermore, it should be understood that the location, arrangement, or configuration of individual components within each of the disclosed embodiments may be modified without departing from the spirit and scope of the present invention.

[0034] Hereinafter, a wet etching method and a mask structure used therein according to embodiments will be described in detail with reference to the drawings.

[0035]

[0036] FIG. 1 is a flow chart illustrating a wet etching method according to one embodiment, FIGS. 2a to 2c are plan views illustrating a wet etching method according to one embodiment, FIGS. 3a to 3c are cross-sectional views illustrating a wet etching method according to one embodiment, and FIGS. 4a to 4d are plan views illustrating a protruding shape of a second mask according to one embodiment.

[0037] The wet etching method described below is assumed to be performed by an automated and mechanized wet etching system.

[0038] According to one embodiment, a wet etching method performs wet etching on an etching target area using only a first mask (Mask1) defining an etching target area of ​​an etching object (Target), and instead performs wet etching on the etching target area using a second mask (Mask 2) placed in an edge area of ​​the etching target area together with the first mask, thereby reducing an etching speed in the edge area of ​​the etching target area and making the etching speed uniform throughout the etching target area, thereby preventing undercutting that may occur in the edge area of ​​the etching target area.

[0039] The second mask may be determined based on the penetration distance of the undercut (hereinafter, the penetration distance of the undercut means the penetration distance of the undercut that occurs when wet etching is performed on an etching target on which only the first mask is placed) to prevent undercut.

[0040] For example, the width, placement position, etc. of the second mask can be determined based on the penetration distance of the undercut, which means that the width of the edge region where the second mask is placed is determined based on the penetration distance of the undercut. For a more specific example, the edge region where the second mask is placed is a region that includes a region spaced 1 um apart from the outer part of the etching target region, and the width of the second mask can also be determined to be around 1 um.

[0041] At this time, the second mask may be formed of a material that reduces the reactivity with the etching solution used for wet etching or the surface roughness in the edge area so as to lower the etching speed in the edge area of ​​the etching target area compared to the etching speed in the central area excluding the edge area of ​​the etching target area.

[0042] Considering that the first mask is formed of a material having minimal reactivity with the etching solution, the second mask can be formed of a material having an etching rate lower than that of the etching target and a higher etching rate than that of the first mask.

[0043] Additionally, the second mask may be formed of a material that is soluble in the etching solution used for wet etching or can be removed through reaction with the etching solution, provided that the second mask reduces reactivity with the etching solution used for wet etching or surface roughness in the edge area.

[0044] For example, when the etching target is silicon and the etching solution used for wet etching is a hydroxide-based solution (e.g., TMAH, KOH, etc.), the second mask may be formed of a silicon-based material, Mo, Zr, or polymer-based material that has solubility in the hydroxide-based etching solution.

[0045] For reference, the etching solution used in wet etching may be an isotropic wet etching solution (e.g., HNA, etc.) as well as an anisotropic etching solution (e.g., hydroxide-based etching solution such as TMAH or KOH).

[0046] Additionally, the second mask may have an extruded shape protruding from at least one vertex on the inner and outer surfaces corresponding to the vertices of the etching target area. The extruded shape may be implemented in various forms that minimize undercuts occurring at the vertices of the etching target area, as shown in FIGS. 4A to 4D.

[0047] In this way, a second mask is used to be placed on the edge area of ​​the etching target area together with the first mask, and wet etching is performed on the etching target area, so that not only undercut but also plateau can be prevented.

[0048] Referring to the drawings, the described wet etching method will be sequentially described. In step (S110), the wet etching system can place a first mask on one surface of an etching target object, excluding the etching target area, to define an etching target area as shown in FIGS. 2A and 3A.

[0049] Next, in step (S120), the wet etching system can place a second mask on the edge area of ​​the etching target area as shown in FIGS. 2b and 3b.

[0050] As described above, the wet etching system can place a second mask in an edge area having a width determined based on the penetration distance of the undercut (assuming that the penetration distance of the undercut occurs when wet etching is performed on an etching target on which only the first mask is placed).

[0051] In step (S130), the wet etching system can perform wet etching on an etching target object on which a first mask and a second mask are arranged, as illustrated in FIGS. 2C and 3C. FIG. 3C illustrates an etching target object from which the first mask has been removed after wet etching has been performed, and the shape and size of the remaining trapezoidal sidewalls after wet etching can be implemented in various ways depending on the degree of etching.

[0052] A mask structure used in a wet etching method according to one embodiment includes a first mask defining an etching target area of ​​an etching object as described above and a second mask disposed at an edge area of ​​the etching target area (see FIGS. 2B and 3B), thereby reducing an etching rate at an edge area of ​​the etching target area during a wet etching process, thereby making the etching rate uniform throughout the etching target area, thereby preventing undercut and plateau that may occur at the edge area of ​​the etching target area, and by being used simultaneously in a single wet etching process, no additional process is required, thereby significantly reducing the process complexity for preventing undercut and plateau.

[0053]

[0054] Although the embodiments described above have been described by way of limited examples and drawings, those skilled in the art will appreciate that various modifications and variations can be made based on the above teachings. For example, appropriate results can still be achieved even if the described techniques are performed in a different order than described, and / or components of the described systems, structures, devices, circuits, etc. are combined or combined in a different manner than described, or are replaced or substituted with other components or equivalents.

[0055] Therefore, other implementations, other embodiments, and equivalents to the claims also fall within the scope of the claims described below.

Claims

1. In the wet etching method, A step of performing wet etching on an etching target area using a first mask defining an etching target area of ​​an etching target object and a second mask placed on an edge area of ​​the etching target area. A wet etching method comprising:

2. In paragraph 1, The above second mask, A wet etching method characterized in that the first mask is disposed in the edge region determined based on the penetration distance of the undercut that occurs when wet etching is performed on the etching target object on which only the first mask is disposed.

3. In paragraph 1, The above second mask, A wet etching method characterized in that the wet etching target area is formed of a material that reduces the reactivity with the etching solution used for the wet etching or the surface roughness in the edge area to reduce the etching rate in the edge area.

4. In paragraph 3, The above second mask, A wet etching method characterized in that the etching target is formed of a material having an etching rate lower than that of the etching target and an etching rate higher than that of the first mask.

5. In paragraph 4, The above second mask, A wet etching method characterized in that the wet etching is formed of a material that is soluble in the etching solution used in the wet etching or can be removed through reaction with the etching solution.

6. In paragraph 1, The above second mask, A wet etching method characterized in that it has a protruding shape protruding from at least one inner and outer vertex corresponding to the vertex of the etching target area.

7. In paragraph 6, The above protruding shape is, A wet etching method characterized by having a shape that minimizes undercut occurring at the vertex of the etching target area.

8. In paragraph 1, The step of performing the above wet etching is: A step of placing the first mask on the remaining area excluding the etching target area on one side of the etching target object based on the etching target area; A step of placing the second mask on the edge area of ​​the etching target area; and A step of performing wet etching on the etching target object on which the first mask and the second mask are placed. A wet etching method characterized by including:

9. In the mask structure used for wet etching, A first mask defining an etching target area of ​​an etching target; and A second mask placed on the edge area of ​​the above etching target area A mask structure including:

10. In paragraph 9, The above second mask, A mask structure characterized in that it is disposed in the edge region determined based on the penetration distance of an undercut that occurs when wet etching is performed on the etching target object on which only the first mask is disposed.

11. In paragraph 9, The above second mask, A mask structure characterized in that it is formed of a material that reduces the reactivity with an etching solution used for the wet etching or the surface roughness in the edge area to reduce the etching rate in the edge area of ​​the etching target area.

12. In paragraph 11, The above second mask, A mask structure characterized in that it is formed of a material having an etching rate lower than that of the etching target and an etching rate higher than that of the first mask.

13. In paragraph 12, The above second mask, A mask structure characterized in that it is formed of a material that is soluble in an etching solution used in the above wet etching or can be removed through a reaction with the etching solution.

14. In paragraph 9, The above second mask, A mask structure characterized by having a protruding shape protruding from at least one inner and outer vertex corresponding to the vertex of the etching target area.

15. In paragraph 9, The above first mask and the above second mask, A mask structure characterized by being used simultaneously in a single wet etching process.

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