MEMS chip and electronic equipment

Abstract

The embodiment of the utility model discloses an MEMS chip and an electronic device, the MEMS chip comprises a substrate, and a vibrating diaphragm, a support layer and a back pole plate which are arranged at the same side of the substrate, the vibrating diaphragm, the support layer and the back pole plate are sequentially laminated in the thickness direction of the substrate, the support layer comprises a first part and a second part filled in the first part, the expansion coefficient of the first part is smaller than that of the second part. According to the MEMS chip, the supporting layer is arranged, so that the overall stress state of the supporting layer can be improved, the total pressure stress of the side, provided with the vibrating diaphragm, of the substrate is reduced, and the overall warping state of the MEMS chip is improved. Compared with the prior art in which the warping mode of the MEMS chip is reduced by increasing the thickness of the back polar plate, the MEMS chip has the advantages that the original size of the MEMS chip is not changed, so that the whole chip becomes heavier and thicker, the heat conduction performance of the chip is not reduced, and the performance and the service life of an electronic element are not influenced.

Description

Technical Field

[0001] The utility model relates to the technical field of micro-electromechanical sensors, in particular to a MEMS chip and electronic equipment. Background Art

[0002] MEMS chip is a semiconductor chip that integrates micro-mechanical devices and electronic components. It uses micro-nano processing technology to manufacture micron-level mechanical structures, which enables the chip to sense, manipulate and control tiny objects. Existing MEMS capacitive pressure chips usually include a substrate and multiple membrane structures. The membrane structures are stacked on the surface of the substrate in the thickness direction of the substrate, such as a diaphragm and a back plate stacked on the surface of the substrate. During the layer-by-layer coating, the substrate and the film will experience simultaneous heating and cooling. Because the expansion coefficient of the substrate and the expansion coefficient of the film are different or the Young's modulus of the substrate and the Young's modulus of the film are different, the shrinkage degree of the substrate and the film is different after cooling. After multiple coatings, the MEMS chip is convex and warped as a whole.

[0003] When the MEMS chip as a whole presents a convex and warped shape, it may cause excessive stress on the internal structure of the chip, thereby damaging the mechanical properties. This may lead to problems such as brittle fracture of the film, material fatigue and failure of the nano / micro structure. Furthermore, the electronic components inside the chip may be affected by the convexity and warping, causing performance changes. For example, the capacitance value of the capacitor, the inductance value of the inductor, etc. may shift, resulting in inaccurate measurement results and reduced system performance. Specifically, when the MEMS chip is used in a microphone, the MEMS microphone has high requirements for the signal-to-noise ratio, often requiring 68db or even above 70dB. When the diaphragm is subjected to stress, the mechanical sensitivity is reduced, which will affect the signal-to-noise ratio of the MEMS microphone.

[0004] Reference Figure 1 In practical applications, the ideal state of a MEMS chip is a "warp-free" state, so that the deformation of the diaphragm is the only variable in the output variable capacitor. However, based on comprehensive considerations of cost, process and other aspects, slight warping is allowed. The commonly used method to improve the warping of MEMS chips is to thicken the back plate. However, increasing the thickness of the back plate will cause the chip to become heavier and thicker as a whole, and will reduce the thermal conductivity of the chip, causing the chip to heat up during operation, affecting the performance and life of the electronic components. For example, when a MEMS chip is used in a microphone, increasing the thickness of the back plate will increase the thermal noise of the system, further reducing the signal-to-noise ratio of the finished product. Utility Model Content

[0005] The embodiments of the utility model provide a MEMS chip and an electronic device, so as to improve the warping phenomenon of the MEMS chip without affecting the performance of the MEMS chip.

[0006] In order to solve the above technical problems, the embodiments of the present utility model disclose the following technical solutions:

[0007] On the one hand, a MEMS chip is provided, comprising: a substrate and a diaphragm, a first supporting layer and a back plate on the same side of the substrate, wherein the diaphragm, the first supporting layer and the back plate are stacked in sequence in the thickness direction of the substrate, the first supporting layer comprises a first part and a second part, and the first part and the second part are nested;

[0008] The expansion coefficient of the first part (201) is smaller than the expansion coefficient of the second part (202).

[0009] In addition to or as an alternative to one or more of the features disclosed above, the Young's modulus of the first portion (201) is smaller than the Young's modulus of the second portion (202).

[0010] In addition to or as an alternative to one or more features disclosed above, in the thickness direction of the substrate, the projection of the back plate covers the projection of the second portion, and the projection of the second portion is located within the projection of the diaphragm.

[0011] In addition to or as an alternative to one or more of the features disclosed above, the first supporting layer further includes a cavity penetrating through its thickness, and the second portion is a continuous annular structure, and the second portion is arranged concentrically with the cavity.

[0012] In addition to or as an alternative to one or more features disclosed above, the second portion includes a first annular structure and a second annular structure, the diameter of the first annular structure is greater than the diameter of the second annular structure, and the first annular structure and the second annular structure are concentric rings.

[0013] In addition to or as an alternative to one or more of the features disclosed above, the first supporting layer further includes a cavity penetrating through the first supporting layer in a thickness direction thereof, and the second portion includes a plurality of second portions, and the plurality of second portions are evenly distributed along an edge of the cavity.

[0014] In addition to or as an alternative to one or more features disclosed above, in the thickness direction of the substrate, the projection shapes of adjacent second portions are different, and the projection shapes of the second portions that are symmetrical about the center of the cavity are the same.

[0015] In addition to or as an alternative to one or more of the features disclosed above, the projection shape is one or more of a polygon and an arcuate shape.

[0016] In addition to or as an alternative to one or more features disclosed above, the first portion is silicon oxide and the second portion is silicon nitride.

[0017] In addition to or as an alternative to one or more of the features disclosed above, the substrate includes a back cavity penetrating through the substrate's thickness, and in the thickness direction of the substrate, a projection range of the cavity covers a projection range of the back cavity.

[0018] In addition to or as an alternative to one or more of the features disclosed above, a second supporting layer is further included between the substrate and the diaphragm, the substrate includes a back cavity penetrating through the substrate in its thickness direction, and the back cavity also penetrates the second supporting layer.

[0019] On the other hand, an electronic device is provided, comprising any MEMS chip disclosed above.

[0020] One of the above technical solutions has the following advantages or beneficial effects: the first support layer between the diaphragm and the back plate can avoid direct contact between the back plate and the diaphragm, and when preparing the MEMS chip, the expansion coefficient of the first support layer is different from the expansion coefficient of the diaphragm, or the Young's modulus of the first support layer is different from the Young's modulus of the diaphragm, and the residual stress state of the first support layer is usually compressive stress during the process of heating up the coating and cooling down the coating. The first support layer of the present application includes a first part and a second part filled in the first part, the expansion coefficient of the first part is less than the expansion coefficient of the second part, or the Young's modulus of the first part is less than the Young's modulus of the first part, and the residual stress state of the first part is compressive stress, and the residual stress state of the second part is tensile stress, so that the overall stress state of the first support layer can be improved, and the total compressive stress on the side of the substrate where the diaphragm is set can be reduced to improve the overall warping state of the MEMS chip. Compared with the prior art which reduces the warping of the MEMS chip by increasing the thickness of the back plate, the present application neither changes the original size of the MEMS chip, making the chip heavier and thicker as a whole, nor reduces the thermal conductivity of the chip, affecting the performance and life of the electronic components. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The technical solutions and other beneficial effects of the present invention will be made apparent by describing in detail the specific embodiments of the present invention in conjunction with the accompanying drawings.

[0022] Figure 1 is a schematic diagram of chip warping provided according to an embodiment of the present application;

[0023] Figure 2 This is a schematic diagram of the structure of a MEMS chip provided according to an embodiment of the present application. Figure 1 ;

[0024] Figure 3 The first support layer structure provided in accordance with the embodiment of the present application is schematically shown in FIG. Figure 1 ;

[0025] Figure 4 The first support layer structure provided in accordance with the embodiment of the present application is schematically shown in FIG. Figure 2 ;

[0026] Figure 5 The first support layer structure provided in accordance with the embodiment of the present application is schematically shown in FIG. Figure 3 ;

[0027] Figure 6 The first support layer structure provided in accordance with the embodiment of the present application is schematically shown in FIG. Figure 4 .

[0028] Description of reference numerals:

[0029] 000, base; 001, back cavity;

[0030] 100, diaphragm;

[0031] 200, first supporting layer; 201, first part; 202, second part; 2021, first annular structure; 2022, second annular structure; 203, cavity;

[0032] 400, back plate; 401, through hole;

[0033] 500. Second supporting layer. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and beneficial effects of the utility model clearer, the utility model is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. It should be understood that the specific implementation methods described in this specification are only for explaining the utility model, and are not intended to limit the utility model.

[0035] In the description of the present utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present utility model, the meaning of "multiple" refers to two or more, unless otherwise clearly and specifically defined.

[0036] In the description of the present utility model, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0037] In the present utility model, unless otherwise clearly stipulated and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0038] The utility model embodiment discloses a MEMS chip, referring to Figure 2The MEMS chip includes a substrate 000 and a diaphragm 100, a first supporting layer 200 and a back plate 400 on the same side of the substrate 000. In the thickness direction of the substrate 000, the diaphragm 100, the first supporting layer 200 and the back plate 400 are stacked in sequence. The diaphragm 100 and the back plate 400 are used to form two electrodes of the capacitor. The first supporting layer 200 is used to support the back plate 400 and isolate the back plate 400 from the diaphragm 100, which not only leaves a deformation space for the diaphragm 100, but also avoids direct contact between the back plate 400 and the diaphragm 100.

[0039] In some embodiments, a second supporting layer 500 is provided between the diaphragm 100 and the substrate 000, and the second supporting layer 500 can prevent the diaphragm 100 from directly contacting the substrate 000. In some embodiments, a plurality of through holes 401 penetrating the thickness of the back plate 400 are provided, and the substrate 000 includes a back cavity 001 penetrating the thickness of the back plate 400. The second supporting layer 500 can avoid the influence on the diaphragm 100 when the back cavity 001 is provided, and the back cavity 001 usually also penetrates the second supporting layer 500. Compared with the first supporting layer 200, the thickness of the second supporting layer 500 is thinner. When preparing the MEMS chip, the residual stress generated by the second supporting layer 500 can be ignored.

[0040] When preparing the MEMS chip, the second support layer 500, the diaphragm 100, the first support layer 200 and the back plate 400 are sequentially formed on the surface of one side of the substrate 000 through the coating process. The main reason for the warping of the MEMS chip is that during the coating, the membrane structure as the substrate and the membrane structure coated on the substrate are heated to a certain temperature at the same time. After the coating is completed, the two are cooled to the initial temperature at the same time. Because the expansion coefficients or Young's moduli of the two are different, when the expansion coefficient of the membrane structure as the substrate is smaller than the expansion coefficient of the membrane structure coated on the substrate, or the Young's modulus of the membrane structure as the substrate is also smaller than the expansion coefficient of the membrane structure coated on the substrate, the membrane structure coated on the substrate will generate tensile stress, and vice versa, compressive stress will be generated.

[0041] In order to improve the warping phenomenon of the MEMS chip without affecting the performance of the MEMS chip, specifically but not limitingly, the present application embodiment proposes a structure of a MEMS chip, and continues to refer to Figure 2 The first supporting layer 200 includes a first part 201 and a second part 202, and the first part 201 and the second part 202 are nested, wherein the expansion coefficient of the first part 201 is smaller than the expansion coefficient of the second part 202, or the Young's modulus of the first part 201 is also smaller than the Young's modulus of the second part 202.

[0042] Specifically, when preparing the MEMS chip, the expansion coefficient of the first support layer 200 is different from the expansion coefficient of the diaphragm 100, or the Young's modulus of the first support layer 200 is different from the Young's modulus of the diaphragm 100. During the process of heating up and cooling down after coating, the residual stress state of the first support layer 200 is usually compressive stress. In the embodiment disclosed in the present application, during the process of heating up and cooling down after coating, the residual stress state of the first part 201 of the first support layer 200 is compressive stress, and the residual stress state of the second part 202 is tensile stress. In this way, the overall stress state of the first support layer 200 can be improved, and the total compressive stress on the side of the substrate 000 where the diaphragm 100 is set can be reduced, so as to improve the overall warping state of the MEMS chip.

[0043] In the thickness direction of the substrate 000, the projection of the back plate 400 covers the projection of the second portion 202, and the projection of the second portion 202 is located within the projection of the diaphragm 100. In different embodiments, the shape of the second portion 202 is different, refer to Figure 3 In some embodiments, the first supporting layer 200 further includes a cavity 203 that runs through the thickness direction of the first supporting layer 200, and the second portion 202 is a continuous annular structure, and the second portion 202 is concentrically arranged with the cavity 203; Figure 4 In some embodiments, the second portion 202 includes a plurality of continuous ring structures. Figure 4 In the illustrated embodiment, the second portion 202 includes a first annular structure 2021 and a second annular structure 2022, the diameter of the first annular structure 2021 is larger than the diameter of the second annular structure 2022, and the first portion 201 is embedded between the first annular structure 2021 and the second annular structure 2022. It should be noted that the material of the first annular structure 2021 and the material of the second annular structure 2022 may be the same or different.

[0044] Reference Figure 5 In some embodiments, the first supporting layer 200 still includes a cavity 203 that runs through the thickness direction of the first supporting layer 200. The difference from the above embodiments is that the second portion 202 includes multiple second portions 202, and the multiple second portions 202 are evenly distributed along the edge of the cavity 203. It should be noted that the materials of adjacent second portions 202 can be the same or different, and the materials of the second portions 202 that are symmetrical about the center of the cavity 203 are the same. Figure 5 In some embodiments, in the thickness direction of the substrate 000, the projection shapes of the adjacent second portions 202 are different, and the projection shapes of the second portions 202 that are symmetrical about the center of the cavity 203 are the same; Figure 6In some embodiments, in the thickness direction of the substrate 000, the projection shape of each second portion 202 is the same. It is worth mentioning that the projection shape can be a polygon, an arcuate shape or an irregular shape, and specifically, the irregular shape can be a petal shape, etc. It should be noted that in some embodiments, in the thickness direction of the substrate 000, the projection range of the cavity 203 covers the projection range of the back cavity 001.

[0045] Further, in different embodiments, the first part 201 can be made of different insulating materials, as long as they have sufficient mechanical properties and are not easily broken during etching. As an example, in the embodiment provided by the present application, the first part 201 is silicon oxide and the second part 202 is silicon nitride. In some embodiments, the diaphragm 100 is made of polysilicon and the substrate 000 is made of silicon.

[0046] At least one embodiment of the present application further provides an electronic device, which includes any of the MEMS chips disclosed above.

[0047] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0048] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A MEMS chip, characterized in that: The invention comprises a substrate (000) and a diaphragm (100), a first supporting layer (200) and a back plate (400) on the same side of the substrate (000); in the thickness direction of the substrate (000), the diaphragm (100), the first supporting layer (200) and the back plate (400) are stacked in sequence; the first supporting layer (200) comprises a first part (201) and a second part (202); the first part (201) and the second part (202) are nested; wherein the expansion coefficient of the first part (201) is smaller than the expansion coefficient of the second part (202).

2. The MEMS chip according to claim 1, characterized in that: The Young's modulus of the first portion (201) is smaller than the Young's modulus of the second portion (202).

3. The MEMS chip according to claim 1, characterized in that: In the thickness direction of the substrate (000), the projection of the back pole plate (400) covers the projection of the second portion (202), and the projection of the second portion (202) is located within the projection of the diaphragm (100).

4. The MEMS chip according to claim 3, characterized in that: The first supporting layer (200) further comprises a cavity (203) penetrating through the thickness of the first supporting layer; the second portion (202) is a continuous annular structure; the second portion (202) and the cavity (203) are arranged concentrically.

5. The MEMS chip according to claim 4, characterized in that: The second part (202) comprises a first annular structure (2021) and a second annular structure (2022), the diameter of the first annular structure (2021) is greater than the diameter of the second annular structure (2022), and the first annular structure (2021) and the second annular structure (2022) are concentrically arranged.

6. The MEMS chip according to claim 3, characterized in that: The first supporting layer (200) further comprises a cavity (203) that runs through the first supporting layer in its thickness direction, and the second portion (202) comprises a plurality of second portions (202), which are evenly distributed along the edge of the cavity (203).

7. The MEMS chip according to claim 6, characterized in that: In the thickness direction of the substrate (000), the projection shapes of adjacent second portions (202) are different, and the projection shapes of the second portions (202) that are symmetrical about the center of the cavity (203) are the same.

8. The MEMS chip according to claim 7, characterized in that: The projection shape is one or more of a polygon and an arcuate shape.

9. The MEMS chip according to any one of claims 1 to 8, characterized in that: The first portion (201) is silicon oxide, and the second portion (202) is silicon nitride.

10. The MEMS chip according to any one of claims 1 to 8, characterized in that: It also includes a second supporting layer (500) located between the substrate (000) and the diaphragm (100), the substrate (000) includes a back cavity (001) that penetrates through its thickness, and the back cavity (001) also penetrates through the second supporting layer (500).

11. An electronic device, characterized in that: Comprising the MEMS chip as described in any one of claims 1-10.

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