Stop structure for improving actuation of MEMS (Micro Electro Mechanical System) movable component and preparation method of stop structure

Abstract

The invention relates to the technical field of integrated circuit manufacturing, and particularly discloses a backstop structure for improving suction of an MEMS movable component and a preparation method thereof, the backstop structure comprises a backstop bump which is arranged on the MEMS movable component or a part of a fixed component opposite to the movable component and is used for controlling the adhesion problem when the MEMS movable component is sucked; and the plurality of vertical cone structures are arranged on the surface of the stop bump and are used for reducing the contact area when the MEMS movable component is attracted. According to the invention, the plurality of vertical cone structures are arranged on the surface of the backstop bump, so that the contact area of the MEMS movable component during actuation is reduced, the problem of actuation and adhesion of the MEMS movable component is effectively solved, and the working reliability of the MEMS movable component is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuit manufacturing, and in particular to a stopper structure for improving the attraction of a MEMS movable component and a preparation method thereof. Background Art

[0002] The movable parts in MEMS devices, especially those with too small movable spacing or too large plate area, often encounter adhesion problems. For some sensitive devices, adhesion problems are a key issue affecting device performance and reliability. Figure 1 (a) is a schematic diagram of the MEMS movable part, and (b) is a schematic diagram of the MEMS movable part being attracted.

[0003] In order to solve the problem of attraction, a common practice is to design a stop structure locally on the movable part, and the stop structure is mostly a small bump. Figure 2 (a) is a schematic diagram of the stopper of a MEMS movable part, and (b) is a schematic diagram of the stopper attraction of a MEMS movable part. Mechanistically, attraction is a manifestation of intermolecular forces, which are related to the surface area of ​​contact. Therefore, the design of the small bump should be as small as possible. However, for MEMS devices used in some impact scenarios, a design that is too small will have strength issues. For some sensitive devices, a design that is too large will not achieve the stopping effect. Designing a stopper structure that can ensure strength while minimizing the contact area becomes a key issue in controlling the attraction of movable parts of MEMS devices.

[0004] Based on this technical background, the present invention proposes a stopper structure for improving the attraction of a MEMS movable component and a preparation method thereof. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention proposes a stop structure and a preparation method for improving the attraction of MEMS movable parts. The stop structure arranges multiple cone structures on the surface of the stop bump, reducing the contact area of ​​the MEMS movable part during attraction, effectively solving the problem of adhesion of the MEMS movable part during attraction, and improving the reliability of the MEMS movable part.

[0006] In order to achieve the above-mentioned object, the first aspect of the present invention provides a stopper structure for improving the engagement of a MEMS movable component, comprising:

[0007] A stopper bump is provided on the MEMS movable component or a portion of the fixed component opposite to the movable component, and is used to control the sticking problem of the MEMS movable component when it is attracted;

[0008] A plurality of cone structures are provided on the surface of the stopper protrusion and are used to reduce the contact area of ​​the MEMS movable component when it is attracted.

[0009] A second aspect of the present invention provides a method for preparing the above-mentioned stop structure, comprising:

[0010] forming a stopper bump on a portion of the MEMS movable component or a fixed component opposite to the movable component;

[0011] A plurality of cone structures are formed on the surface of the stop protrusion.

[0012] The technical effects of the present invention include:

[0013] (1) The present invention proposes a stopper structure for improving the attraction of MEMS movable parts. The stopper structure sets multiple cone structures on the surface of the stopper protrusion, which reduces the contact area of ​​the MEMS movable part during attraction, effectively solves the problem of adhesion of the MEMS movable part during attraction, and improves the reliability of the MEMS movable part.

[0014] (2) The stopper structure for improving the attraction of the MEMS movable parts proposed in the present invention controls the size of the multiple cone structures by the etching depth of the crystal-direction selective etching, thereby increasing the volume of the multiple cone structures and further enhancing the strength of the multiple cone structures. At the same time, the tip of each cone structure is flattened by the non-crystal-direction selective etching, thereby further enhancing the impact strength of the multiple cone structures.

[0015] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0017] Figure 1 (a) is a schematic diagram of the MEMS movable part, and (b) is a schematic diagram of the MEMS movable part being attracted.

[0018] Figure 2 (a) is a schematic diagram of the stop of the MEMS movable part, and (b) is a schematic diagram of the stop attraction of the MEMS movable part.

[0019] Figure 3 This is a schematic diagram of the stop structure proposed by the present invention for improving the engagement of MEMS movable components.

[0020] Figure 4 This is a microscopic diagram of a cone structure in a specific embodiment of the stop structure for improving the engagement of a MEMS movable component proposed by the present invention.

[0021] Figure 5The figure is a flow chart of a specific embodiment of the method for preparing a stopper structure for improving the attraction of a MEMS movable component proposed in the present invention. DETAILED DESCRIPTION

[0022] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0023] In the present invention, unless otherwise specified, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of a device in normal use, and "inner" and "outer" refer to positions relative to the device's outline. Furthermore, the terms "first, second, and third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly specifying the number of the technical features indicated. Therefore, features defined as "first, second, and third" may explicitly or implicitly include one or more of such features. In the description of the present invention, "plurality" means two or more, unless otherwise explicitly and specifically defined.

[0024] The present invention provides a stopper structure for improving the engagement of a MEMS movable component, such as Figure 3 Shown, including:

[0025] A stopper bump is provided on the MEMS movable part or a part of the fixed part opposite to the movable part, and is used to control the sticking problem when the MEMS movable part is attracted;

[0026] A plurality of vertical cone structures are arranged on the surface of the stopper protrusion to reduce the contact area when the MEMS movable part is attracted.

[0027] In the present invention, the stop structure sets multiple cone structures on the surface of the stop bump, reducing the contact area of ​​the MEMS movable part when it is attracted, effectively solving the problem of adhesion of the MEMS movable part when it is attracted, and improving the reliability of the MEMS movable part.

[0028] According to the present invention, a plurality of vertical pyramid structures are formed by crystal-direction selective etching.

[0029] According to the present invention, the size of the plurality of pyramid structures is controlled by the etching depth of the crystal direction selective etching;

[0030] The deeper the etching depth, the larger the volume of the multiple pyramid structures, and thus the stronger the strength.

[0031] According to the present invention, the tip of each cone structure is flattened to enhance the impact strength of the multiple cone structures.

[0032] According to the present invention, the flattened tip of each pyramidal structure is formed by amorphous selective etching.

[0033] In the present invention, the size of the multiple cone structures is controlled by the etching depth of the crystal-direction selective etching, thereby increasing the volume of the multiple cone structures and thereby enhancing the strength of the multiple cone structures. At the same time, the tip of each cone structure is flattened by the amorphous-direction selective etching, thereby further enhancing the impact strength of the multiple cone structures.

[0034] The present invention also provides a method for preparing a stopper structure for improving the engagement of a MEMS movable component, comprising:

[0035] forming a stopper bump on a portion of the MEMS movable component or a fixed component opposite to the movable component;

[0036] A plurality of cone structures are formed on the surface of the stop protrusion.

[0037] According to the present invention, forming a stopper bump on a portion of a MEMS movable component or a fixed component opposite to the movable component includes:

[0038] Photolithography and dry etching are sequentially performed on the surface of the MEMS movable component or the fixed component opposite to the movable component to form a stopper bump locally.

[0039] According to the present invention, forming a plurality of cone structures on the surface of the stopper protrusion includes:

[0040] A plurality of vertical cone structures are formed on the surface of the stopper bump by crystal-direction selective etching, and the size of the vertical cone structure is controlled by the etching depth of the crystal-direction selective etching.

[0041] According to the present invention, it also includes:

[0042] The tip of each cone structure is flattened by selective etching in the amorphous direction.

[0043] According to the present invention, the etching solution for crystal orientation selective etching is a strong alkaline solution;

[0044] Amorphous selective etching adopts dry etching, or wet etching using a strong acid solution as the etching solution.

[0045] In the present invention, the strong base solution may be a potassium hydroxide solution or a sodium hydroxide solution; the strong acid solution may be a nitric acid solution or a hydrofluoric acid solution.

[0046] The present invention will be described in more detail below through specific examples.

[0047] Example 1

[0048] like Figure 3 As shown, this embodiment provides a stopper structure for improving the engagement of a MEMS movable component, including:

[0049] The stopper bump is provided on a part of the MEMS movable part to control the sticking problem when the MEMS movable part is attracted;

[0050] A plurality of vertical cone structures are provided on the surface of the stopper protrusion to reduce the contact area when the MEMS movable part is attracted;

[0051] In this embodiment, multiple cone structures are formed by selective etching in the crystal direction. The microscopic diagram of the cone structure is shown in FIG. Figure 4 As shown;

[0052] The size of the multiple pyramidal structures is controlled by the etching depth of the crystal direction selective etching;

[0053] The deeper the etching depth, the larger the volume of the multiple cone structures, and thus the stronger their strength;

[0054] The tip of each cone structure is flattened to enhance the impact strength of the multiple cone structures;

[0055] In this embodiment, the flattened tip of each pyramidal structure is formed by amorphous selective etching.

[0056] This embodiment also provides a method for preparing a stopper structure for improving the engagement of a MEMS movable component. Figure 5 Shown, including:

[0057] Photolithography and dry etching are sequentially performed on the surface of the MEMS movable component to form a stopper bump locally thereon;

[0058] A plurality of vertical cone structures are formed on the surface of the stopper bump by selective etching in the crystal direction, and the size of the vertical cone structure is controlled by the etching depth of the selective etching in the crystal direction;

[0059] By selective etching in the amorphous direction, the tip of each cone structure is flattened;

[0060] In this embodiment, the etchant for the crystal-direction selective etching is a strong alkaline solution, and the amorphous-direction selective etching adopts wet etching with the etchant being a strong acid solution, wherein the strong alkaline solution is a potassium hydroxide solution and the strong acid solution is a hydrofluoric acid solution.

[0061] In this embodiment, crystal-direction selective etching is used to realize the cone structure of the stop bump, reducing the contact surface area and thus reducing attraction; strength control can control the size of the raised cone structure by controlling the etching depth. The deeper the depth, the larger the cone volume and the enhanced strength; under large impact requirements, the cone part has poor impact resistance, so an additional step of non-crystal-direction selective etching is selected to flatten the cone to enhance the impact strength.

[0062] The embodiment of the present invention proposes a stop structure for improving the attraction of MEMS movable parts, and multiple cone structures are set on the surface of the stop bump, which reduces the contact area of ​​the MEMS movable parts during attraction, effectively solves the problem of adhesion of the MEMS movable parts, and improves the reliability of the operation of the MEMS movable parts.

[0063] While various embodiments of the present invention have been described above, the above description is intended to be illustrative, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A stopper structure for improving the engagement of a MEMS movable component, characterized in that: include: A stopper bump is provided on the MEMS movable component or a portion of the fixed component opposite to the movable component, and is used to control the sticking problem of the MEMS movable component when it is attracted; A plurality of cone structures are provided on the surface of the stopper protrusion and are used to reduce the contact area of ​​the MEMS movable component when it is attracted.

2. The stop structure according to claim 1, characterized in that: The plurality of vertical cone structures are formed by crystal-direction selective etching.

3. The stop structure according to claim 2, characterized in that: The sizes of the plurality of cone structures are controlled by the etching depth of the crystal direction selective etching; The deeper the etching depth is, the larger the volume of the plurality of pyramid structures is, and thus the stronger the strength is.

4. The stop structure according to claim 1, characterized in that: The tip of each cone structure is flattened to enhance the impact strength of the multiple cone structures.

5. The stop structure according to claim 1, characterized in that: The flattened tip of each pyramidal structure is formed by amorphous selective etching.

6. A method for preparing a stopper structure for improving the attraction of a MEMS movable part, characterized in that: include: forming a stopper bump on a portion of the MEMS movable component or a fixed component opposite to the movable component; A plurality of cone structures are formed on the surface of the stop protrusion.

7. The preparation method according to claim 6, characterized in that Forming a stop bump on a portion of a MEMS movable component or a fixed component opposite to the movable component includes: Photolithography and dry etching are sequentially performed on the surface of the MEMS movable component or the fixed component opposite to the movable component to form a stopper bump locally.

8. The preparation method according to claim 6, characterized in that Forming a plurality of cone structures on the surface of the stopper protrusion includes: A plurality of vertical cone structures are formed on the surface of the stopper bump by crystal-direction selective etching, and the size of the vertical cone structure is controlled by the etching depth of the crystal-direction selective etching.

9. The preparation method according to claim 6, characterized in that Also includes: The tip of each cone structure is flattened by selective etching in the amorphous direction.

10. The preparation method according to claim 8 or 9, characterized in that: The etching solution for the crystal orientation selective etching is a strong alkaline solution; The amorphous selective etching is performed by dry etching or wet etching using a strong acid etching solution.

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