Inertial sensor and preparation method thereof

Abstract

The invention discloses an inertial sensor and a preparation method thereof. The inertial sensor comprises a first substrate; a dielectric layer; a plurality of first openings are formed in the first conductive layer; the second conducting layers are bonded on the first conducting layer through bonding structures, gaps are formed between the adjacent second conducting layers from bottom to top, the adjacent second conducting layers are connected through connecting parts, and each second conducting layer is provided with a plurality of second openings; and the second substrate covers the first substrate, and a closed space is defined between the second substrate and the first substrate. Compared with the prior art, by arranging the multiple second conductive layers, compared with a traditional single-layer structure, the size of a mold is reduced to be smaller, the manufacturing cost is reduced, integration of equipment and portable consumer application is improved, meanwhile, the large movable conductive structure has the larger surface area, and the sensitivity of the X axis and the Y axis can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-electromechanical systems, and in particular to an inertial sensor and a preparation method thereof. Background Art

[0002] In the prior art, an inertial sensor includes a movable conductive structure and an immovable conductive structure that are relatively arranged. When the movable conductive structure is displaced, the distance between the movable conductive structure and the immovable conductive structure changes, so that a capacitance signal in a corresponding direction can be detected to realize inertia detection.

[0003] Inertial sensors continue to improve performance and smaller die size to enhance user experience and new applications. By shrinking the chip size without stacked device structures, movable conductive structures tend to reduce surface area, resulting in reduced sensor performance. Summary of the invention

[0004] The purpose of the present invention is to provide an inertial sensor and a method for preparing the same, so as to solve the technical problems in the prior art.

[0005] In a first aspect, the present invention provides an inertial sensor, comprising:

[0006] a first substrate;

[0007] a dielectric layer, the dielectric layer being stacked on the first substrate;

[0008] A first conductive layer, wherein the first conductive layer is stacked on the dielectric layer, and the first conductive layer has a plurality of first openings therein, and the plurality of first openings are distributed at intervals along a radial direction of the first conductive layer;

[0009] A plurality of second conductive layers, wherein the plurality of second conductive layers are bonded to the first conductive layer through a bonding structure, and from bottom to top, there are gaps between adjacent second conductive layers, and adjacent second conductive layers are connected through connecting parts, and each second conductive layer has a plurality of second openings, and the plurality of second openings are spaced apart along the radial direction of the second conductive layer;

[0010] The second substrate is covered on the first substrate, and the second substrate and the first substrate form a closed space.

[0011] In the inertial sensor as described above, preferably, the connecting portion includes a plurality of first connectors, the plurality of first connectors are arranged at intervals along the radial direction of the second conductive layer, and two ends of the first connectors are respectively connected to two adjacent second conductive layers.

[0012] In the inertial sensor as described above, preferably, the first connector corresponds to the position of the bonding structure.

[0013] An inertial sensor as described above, wherein preferably, the connecting portion further includes a plurality of second connectors, the plurality of second connectors are arranged at intervals along the radial direction of the second conductive layer, the two ends of the second connectors are respectively connected to two adjacent second conductive layers, and the width of the second connectors is smaller than the width of the first connectors.

[0014] In the inertial sensor as described above, preferably, a plurality of the second connectors are arranged close to the edge of the second conductive layer.

[0015] In the inertial sensor as described above, preferably, both the first connector and the second connector are made of conductive materials.

[0016] In the inertial sensor as described above, preferably, the connecting portion is bonded and fixed to the second conductive layer.

[0017] In the inertial sensor as described above, preferably, the bonding structure includes a first bonding layer and a second bonding layer bonded to each other, the first bonding layer is stacked on top of the first conductive layer, and the second bonding layer is stacked on the bottom of the second conductive layer.

[0018] In the inertial sensor as described above, preferably, a groove is formed on the surface of the second substrate facing the first substrate.

[0019] In a second aspect, the present invention further provides a method for preparing an inertial sensor, which is used to prepare the aforementioned inertial sensor, wherein the inertial sensor comprises:

[0020] a first substrate;

[0021] a dielectric layer, the dielectric layer being stacked on the first substrate;

[0022] A first conductive layer, wherein the first conductive layer is stacked on the dielectric layer, and the first conductive layer has a plurality of first openings therein, and the plurality of first openings are distributed at intervals along a radial direction of the first conductive layer;

[0023] Multiple layers of second conductive layers, the multiple layers of second conductive layers are bonded to the first conductive layer through a bonding structure, from bottom to top, there are gaps between adjacent second conductive layers, adjacent second conductive layers are connected by connecting parts, each layer of the second conductive layer has a plurality of second openings, and the plurality of second openings are distributed at intervals along the radial direction of each layer of the second conductive layer;

[0024] The bonding structure comprises a first bonding layer and a second bonding layer which are bonded to each other, wherein the first bonding layer is stacked on the top of the first conductive layer, and the second bonding layer is stacked on the bottom of the second conductive layer;

[0025] a second substrate, the second substrate covering the first substrate, the second substrate and the first substrate forming a closed space;

[0026] The preparation method comprises the following steps:

[0027] forming the second conductive layer on the second substrate, and forming the second opening on the second conductive layer;

[0028] depositing a sacrificial layer on the second conductive layer;

[0029] forming a second conductive layer on the sacrificial layer, and forming the second opening on the second conductive layer;

[0030] connecting the adjacent second conductive layers using the connecting portion;

[0031] forming the second bonding layer on the second conductive layer;

[0032] forming the dielectric layer and the first conductive layer on the first substrate, and forming the first opening on the first conductive layer;

[0033] forming the first bonding layer on the first conductive layer;

[0034] Bonding the first bonding layer and the second bonding layer at high temperature, so that the second substrate and the first substrate enclose a closed space;

[0035] The sacrificial layer is removed.

[0036] Compared with the prior art, the present invention reduces the mold size to a smaller size compared with the traditional single-layer structure by setting a multi-layer second conductive layer, thereby reducing the manufacturing cost and improving the integration of the device with portable consumer applications. At the same time, the larger movable conductive structure has a larger surface area, which can improve the XY axis sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a cross-sectional schematic diagram of an inertial sensor according to an embodiment of the present invention;

[0038] Figure 2a-2c It is a flow chart of the preparation of the inertial sensor according to the embodiment of the present invention.

[0039] Explanation of the reference numerals: 1-first substrate, 2-dielectric layer, 3-first conductive layer, 4-first opening, 5-second conductive layer, 6-second opening, 7-connecting portion, 71-first connector, 72-second connector, 8-bonding structure, 81-first bonding layer, 82-second bonding layer, 9-second substrate, 10-groove, 11-movable mass block, 12-sacrificial layer. DETAILED DESCRIPTION

[0040] The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, but should not be construed as limiting the present invention.

[0041] like Figure 1 As shown, an embodiment of the present invention provides an inertial sensor, which includes, from bottom to top, a first substrate 1, a dielectric layer 2, a first conductive layer 3, a bonding structure 8, a multi-layer second conductive layer 5 and a second substrate 9, wherein:

[0042] The first substrate 1 is a semiconductor substrate, such as a silicon substrate. In a feasible implementation, the first substrate 1 is circular. Those skilled in the art will appreciate that the first substrate 1 may also be in other shapes, such as a square, etc., which is not limited here.

[0043] The dielectric layer 2 is stacked on the first substrate 1. The shape of the dielectric layer 2 is adapted to the shape of the first substrate 1. The dielectric layer 2 is used to support the first conductive layer 3 and realize electrical isolation between the first conductive layer 3 and the first substrate 1. In a feasible implementation, the dielectric layer 2 is made of silicon dioxide.

[0044] The first conductive layer 3 is stacked on the dielectric layer 2. The shape of the first conductive layer 3 is adapted to the shape of the dielectric layer 2. The first conductive layer 3 has a plurality of first openings 4. The first openings 4 are annular groove structures. The plurality of first openings 4 are arranged in sequence with the axis of the first conductive layer 3 as the center. The inner diameters of adjacent first openings 4 may be the same or different, which is not limited here. The first conductive layer 3 is made of a conductive material, such as polysilicon.

[0045] The multiple layers of second conductive layers 5 are bonded to the first conductive layer 3 through a bonding structure 8. From bottom to top, there are gaps between adjacent second conductive layers 5 to provide space for the second conductive layers 5 to deform. Adjacent second conductive layers 5 are connected by connecting parts 7. Each second conductive layer 5 has a plurality of second openings 6. The second openings 6 are annular groove structures. The plurality of second openings 6 are arranged in sequence with the axis of the second conductive layer 5 as the center. The inner diameters of adjacent second openings 6 may be the same or different, which is not limited here. The second conductive layer 5 is made of a conductive material, such as polysilicon.

[0046] The second substrate 9 is covered on the first substrate 1. The second substrate 9 is a semiconductor substrate, such as a silicon substrate. In a feasible implementation, the second substrate 9 is circular. Those skilled in the art will appreciate that the second substrate 9 may also be in other shapes, such as a square, etc., which are not limited here. The second substrate 9 and the first substrate 1 form a closed space, so that the internal structure of the inertial sensor is protected from interference from the external environment, making it easier to control the air pressure in the cavity and improving working stability.

[0047] In the above embodiment, by setting a multi-layer second conductive layer 5, compared with the traditional single-layer structure, the mold size is reduced to a smaller size, the manufacturing cost is reduced, and the integration of the device with portable consumer applications is improved. At the same time, the larger movable conductive structure has a larger surface area, which can improve the XY axis sensitivity.

[0048] Furthermore, the connecting portion 7 includes a plurality of first connecting bodies 71, and the plurality of first connecting bodies 71 are arranged at intervals along the radial direction of the second conductive layer 5. The two ends of the first connecting body 71 are respectively connected to two adjacent second conductive layers 5. The first connecting body 71 plays a role of supporting, fixing and electrically connecting. In the horizontal direction, a preset distance is maintained between adjacent first connecting bodies 71, and in the vertical direction, there is a gap between adjacent second conductive layers 5, thereby providing the second conductive layer 5 with a certain deformation space.

[0049] In a feasible implementation mode, referring to Figure 1 As shown, the position of the first connector 71 corresponds to the bonding structure 8, a cavity is formed between adjacent bonding structures 8, and the second conductive layer 5 located above the cavity is a movable mass block 11. When the movable mass block 11 is displaced, the distance between it and the first conductive layer 3 is changed, so that a capacitance signal in a corresponding direction can be detected to realize the detection of inertia. The connection position of the first connector 71 is set corresponding to the position of the bonding structure 8 from bottom to top, so that the displacement process of the movable mass blocks 11 of multiple second conductive layers 5 will tend to be consistent, which can effectively improve the sensitivity and reliability of the inertial sensor.

[0050] Reference Figure 1 As shown, the connecting portion 7 also includes a plurality of second connectors 72, and the plurality of second connectors 72 are arranged at intervals along the radial direction of the second conductive layer 5. The two ends of the second connector 72 are respectively connected to two adjacent second conductive layers 5. The width of the second connector 72 is smaller than the width of the first connector 71. On the one hand, the second connector 72 can improve the connection reliability between the two adjacent second conductive layers 5. On the other hand, by setting the second connector 72 narrower than the first connector 71, the second conductive layer 5 forms a larger surface area, and the flexibility of the second conductive layer 5 is better guaranteed.

[0051] Further, refer to Figure 1 As shown, a plurality of second connectors 72 are arranged near the edge of the second conductive layer 5. Since the deflection of the second conductive layer 5 is parabolic, the deflection of the second conductive layer 5 at the center position is the largest, and the deflection of the second conductive layer 5 at the edge position is smaller. The second connectors 72 are arranged at the place where the movement of the second conductive layer 5 is the smallest, thereby improving the sensitivity of the inertial sensor.

[0052] In the embodiment provided in the present application, the first connector 71 and the second connector 72 are both made of conductive materials, such as polysilicon, and the connecting portion 7 is bonded and fixed to the second conductive layer 5. This makes it easy to manufacture, and up to two or more layers can continue to be stacked in the device structure.

[0053] Reference Figure 1 As shown, the bonding structure 8 includes a first bonding layer 81 and a second bonding layer 82 which are bonded to each other. The first bonding layer 81 is stacked on the top of the first conductive layer 3, and the second bonding layer 82 is stacked on the bottom of the second conductive layer 5. The first bonding layer 81 and the second bonding layer 82 are both ring structures. The first bonding layer 81 and the second bonding layer 82 are both made of metal to form metal hot pressing bonding.

[0054] Based on the above embodiments, refer to Figure 2a-2c As shown, the present invention also provides a method for preparing an inertial sensor, the preparation method comprising the following steps:

[0055] S101: forming a second conductive layer 5 on the second substrate 9, and forming a second opening 6 on the second conductive layer 5;

[0056] In this step, a resist layer is formed on the bottom surface of the second substrate 9, the resist layer is patterned by a photolithography process to form a mask, and the second substrate 9 is etched through the mask to form a groove 10. A second conductive layer 5 is formed on the second substrate 9 by deposition, a resist layer is deposited on the surface of the second conductive layer 5, the resist layer is patterned by a photolithography process to form a mask, and the second conductive layer 5 is etched through the mask to form a second opening 6 penetrating the second conductive layer 5.

[0057] S102: depositing a sacrificial layer 12 on the second conductive layer 5;

[0058] In this step, the material of the sacrificial layer 12 may be PSG. The sacrificial layer 12 is deposited to a certain thickness and then removed later to form a gap between the two second conductive layers 5 .

[0059] S103: forming another second conductive layer 5 on the sacrificial layer 12, and forming a second opening 6 on the second conductive layer 5;

[0060] In the embodiment of the present application, two second conductive layers 5 are provided. Those skilled in the art will appreciate that more second conductive layers 5 may be provided, which is not limited herein. In this step, a resist layer is deposited on the surface of the second conductive layer 5, the resist layer is patterned using a photolithography process to form a mask, and the second conductive layer 5 is etched through the mask to form a second opening 6 penetrating the second conductive layer 5.

[0061] S104: connecting adjacent second conductive layers 5 using the connecting portion 7;

[0062] In this step, the first connector 71 and the second connector 72 are fixed to two adjacent second conductive layers 5 by bonding, and multiple first connectors 71 are arranged in a ring-shaped manner with the axis of the second conductive layer 5 as the center, and multiple second connectors 72 are arranged at the edge of the second conductive layer 5 and located between the two first connectors 71.

[0063] S105: forming a second bonding layer 82 on the second conductive layer 5;

[0064] In this step, a second bonding layer 82 is formed on the surface of the second conductive layer 5 by, for example, deposition and etching.

[0065] S106: forming a dielectric layer 2 and a first conductive layer 3 on the first substrate 1, and forming a first opening 4 on the first conductive layer 3;

[0066] In this step, a dielectric layer 2 is formed on the first substrate 1 by deposition, a first conductive layer 3 is formed on the dielectric layer 2 by deposition, a resist layer is deposited on the surface of the first conductive layer 3, the resist layer is patterned by a photolithography process to form a mask, and the first conductive layer 3 is etched through the mask to form a first opening 4 penetrating the first conductive layer 3.

[0067] S107: forming a first bonding layer 81 on the first conductive layer 3;

[0068] In this step, a first bonding layer 81 is formed on the surface of the first conductive layer 3 by, for example, deposition and etching.

[0069] S108: bonding the first bonding layer 81 and the second bonding layer 82 at high temperature, so that the second substrate 9 and the first substrate 1 are enclosed to form a closed space;

[0070] S109: removing the sacrificial layer 12.

[0071] The above describes in detail the structure, features and effects of the present invention based on the embodiments shown in the drawings. The above is only a preferred embodiment of the present invention, but the present invention is not limited to the scope of implementation shown in the drawings. Any changes made according to the concept of the present invention, or modifications to equivalent embodiments with equivalent changes, which still do not exceed the spirit covered by the description and drawings, should be within the protection scope of the present invention.

Claims

1. An inertial sensor, It is characterized in that include: a first substrate; a dielectric layer, the dielectric layer being stacked on the first substrate; A first conductive layer, wherein the first conductive layer is stacked on the dielectric layer, and the first conductive layer has a plurality of first openings therein, and the plurality of first openings are distributed at intervals along a radial direction of the first conductive layer; A plurality of second conductive layers, wherein the plurality of second conductive layers are bonded to the first conductive layer through a bonding structure, and from bottom to top, there are gaps between adjacent second conductive layers, and adjacent second conductive layers are connected through connecting parts, and each second conductive layer has a plurality of second openings, and the plurality of second openings are spaced apart along the radial direction of the second conductive layer; The second substrate is covered on the first substrate, and the second substrate and the first substrate form a closed space.

2. The inertial sensor according to claim 1, Features: The connecting portion includes a plurality of first connecting bodies, which are arranged at intervals along the radial direction of the second conductive layer, and two ends of the first connecting body are respectively connected to two adjacent second conductive layers.

3. The inertial sensor according to claim 2, Features: The first connector corresponds to the position of the bonding structure.

4. The inertial sensor according to claim 2, Features: The connecting portion further includes a plurality of second connectors, which are spaced apart along the radial direction of the second conductive layer, and the two ends of the second connectors are respectively connected to two adjacent second conductive layers, and the width of the second connectors is smaller than that of the first connectors.

5. The inertial sensor according to claim 4, Features: A plurality of the second connectors are arranged near the edge of the second conductive layer.

6. The inertial sensor according to claim 4, Features: The first connector and the second connector are both made of conductive materials.

7. The inertial sensor according to claim 4, Features: The connecting portion is bonded and fixed to the second conductive layer.

8. The inertial sensor according to claim 1, Features: The bonding structure includes a first bonding layer and a second bonding layer which are bonded to each other. The first bonding layer is stacked on top of the first conductive layer, and the second bonding layer is stacked on the bottom of the second conductive layer.

9. The inertial sensor according to claim 1, Features: A groove is formed on a surface of the second substrate facing the first substrate.

10. A method for preparing an inertial sensor, for preparing the inertial sensor according to any one of claims 1 to 9, It is characterized in that The inertial sensor comprises: a first substrate; a dielectric layer, the dielectric layer being stacked on the first substrate; A first conductive layer, wherein the first conductive layer is stacked on the dielectric layer, and the first conductive layer has a plurality of first openings therein, and the plurality of first openings are distributed at intervals along a radial direction of the first conductive layer; Multiple layers of second conductive layers, the multiple layers of second conductive layers are bonded to the first conductive layer through a bonding structure, from bottom to top, there are gaps between adjacent second conductive layers, adjacent second conductive layers are connected by connecting parts, each layer of the second conductive layer has a plurality of second openings, and the plurality of second openings are distributed at intervals along the radial direction of each layer of the second conductive layer; The bonding structure comprises a first bonding layer and a second bonding layer which are bonded to each other, wherein the first bonding layer is stacked on the top of the first conductive layer, and the second bonding layer is stacked on the bottom of the second conductive layer; a second substrate, the second substrate covering the first substrate, the second substrate and the first substrate forming a closed space; The preparation method comprises the following steps: forming the second conductive layer on the second substrate, and forming the second opening on the second conductive layer; depositing a sacrificial layer on the second conductive layer; forming a second conductive layer on the sacrificial layer, and forming the second opening on the second conductive layer; connecting the adjacent second conductive layers using the connecting portion; forming the second bonding layer on the second conductive layer; forming the dielectric layer and the first conductive layer on the first substrate, and forming the first opening on the first conductive layer; forming the first bonding layer on the first conductive layer; Bonding the first bonding layer and the second bonding layer at high temperature, so that the second substrate and the first substrate enclose a closed space; The sacrificial layer is removed.

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