Three-mass-block Z-axis accelerometer and manufacturing method thereof

Abstract

A three-mass-block Z-axis accelerometer comprises a complementary metal oxide semiconductor substrate, a micro-electro-mechanical substrate and a cap substrate, wherein the complementary metal oxide semiconductor substrate, the micro-electro-mechanical substrate and the cap substrate are oppositely arranged in parallel and are bonded with one another. The micro-electro-mechanical substrate comprises a connecting mass block which is arranged between the two seesaw mass blocks and is connected with the two seesaw mass blocks through connecting springs. The connecting mass block and the two seesaw mass blocks respectively correspond to a plurality of sensing electrode plates on the complementary metal oxide semiconductor substrate to form a plurality of capacitor structures. The micro-electro-mechanical substrate further comprises a plurality of electrical connection anchor point structures which are respectively fixed and electrically connected with the complementary metal oxide semiconductor substrate and the cap substrate, and a plurality of cap fixing anchor point structures which are respectively fixedly connected with the cap substrate.

Description

Technical Field

[0001] The present invention relates to the field of micro-electromechanical systems for detecting acceleration, and in particular to the field of a Z-axis accelerometer for detecting the direction of gravity acceleration. Background Art

[0002] Micro-electromechanical systems (MEMS) refer to mechanical and electromechanical systems in which some components have mechanical functionality and can be used to quickly and accurately detect small changes in physical properties. Regarding Z-axis accelerometers using MEMS, Taiwan Patent Publication No. I762816 discloses a Z-axis seesaw accelerometer with an embedded movable structure, which can be pivoted or shifted away from the plane of the seesaw beam to increase sensitivity. Taiwan Patent Publication No. I716999 discloses a design with a pivot rod suspended on a substrate, and the pivot rod and the substrate are separated by a non-uniform spacing distance to increase sensitivity. Summary of the invention

[0003] The present invention provides a three-mass Z-axis accelerometer and a manufacturing method thereof. The MEMS sensing structure has two anchoring structures, which serve as a fixed structure and an electrical conductive structure respectively, so as to avoid structural damage to the fixed structure due to bonding pressure during the manufacturing process.

[0004] The present invention provides a three-mass Z-axis accelerometer and a manufacturing method thereof. The MEMS sensing structure has a connecting mass block and two seesaw mass blocks on both sides, and can measure acceleration in the Z-axis direction.

[0005] The present invention provides a three-mass Z-axis accelerometer and a manufacturing method thereof. The MEMS sensing structure has a bow-shaped compensation capacitor structure to reduce the influence of stress formed by factors such as the manufacturing process.

[0006] A three-mass Z-axis accelerometer, comprising a complementary metal oxide semiconductor (CMOS) substrate, a microelectromechanical (MEMS) substrate and a cap substrate, which are arranged in parallel and bonded to each other, characterized in that the microelectromechanical (MEMS) substrate comprises: two seesaw masses; a connecting mass block is arranged between the two seesaw masses and is respectively connected to the two seesaw masses through a plurality of connecting springs, and a hollow area is provided between the connecting mass block and any of the seesaw masses, wherein the connecting mass block and the two seesaw masses correspond to the complementary metal oxide semiconductor substrate respectively. Multiple sensing electrode plates are arranged on the cap substrate to form multiple capacitor structures; multiple electrical connection anchor structures are respectively fixed to and electrically connected with the complementary metal oxide semiconductor substrate and the cap substrate, wherein any of the electrical connection anchor structures corresponds to fixing a first cap top column of the cap substrate and a bonding pad of the complementary metal oxide semiconductor substrate; and multiple cap fixing anchor structures are respectively fixed to the cap substrate, wherein any of the cap fixing anchor structures corresponds to fixing a second cap top column of the cap substrate, and the electrical connection anchor structures and the cap fixing anchor structures are arranged in the hollow areas.

[0007] In some embodiments, the micro-electromechanical system substrate further includes a plurality of bow-shaped compensation capacitor structures disposed around the connection mass block and the seesaw mass blocks.

[0008] A method for manufacturing the above-mentioned three-mass Z-axis accelerometer includes: providing the cap substrate including the first cap top pillars and the second cap top pillars; melting and bonding an original substrate to the cap substrate; patterning the original substrate to form the micro-electromechanical substrate; providing the complementary metal oxide semiconductor substrate including the bonding pads and the sensing electrode plates; and metal eutectic bonding the micro-electromechanical substrate and the complementary metal oxide semiconductor substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 FIG. 4 is a side view of a first embodiment of a three-mass Z-axis accelerometer of the present invention.

[0010] Figure 2 It is a front view of a first embodiment of the MEMS substrate structure of a three-mass Z-axis accelerometer embodiment of the present invention.

[0011] Figure 3 FIG. 4 is a partial side view of a MEMS sensing structure of an embodiment of a three-mass Z-axis accelerometer of the present invention.

[0012] Figure 4 FIG. 4 is a partial side view of a MEMS sensing structure of an embodiment of a three-mass Z-axis accelerometer of the present invention.

[0013] Figure 5FIG. 4 is a partial side view of a MEMS sensing structure of an embodiment of a three-mass Z-axis accelerometer of the present invention.

[0014] Figure 6 It is a front view of a second embodiment of the MEMS substrate structure of the three-mass Z-axis accelerometer embodiment of the present invention.

[0015] Figure 7 for Figure 6 Schematic diagram of the cross section along the BB' line.

[0016] Figure 8 It is a front view schematic diagram of the compensation capacitor structure of the second embodiment of the MEMS substrate structure of the three-mass Z-axis accelerometer embodiment of the present invention.

[0017] Fig. 9 It is a front view schematic diagram of the arrangement relationship between the three-mass sensing structure and the compensation capacitor structure of the MEMS substrate structure of the three-mass Z-axis accelerometer embodiment of the present invention.

[0018] Fig.10 It is a front view schematic diagram of the arrangement relationship between the three-mass sensing structure and the compensation capacitor structure of the MEMS substrate structure of the three-mass Z-axis accelerometer embodiment of the present invention.

[0019] Fig.11 It is a front view schematic diagram of the arrangement relationship between the three-mass sensing structure and the compensation capacitor structure of the MEMS substrate structure of the three-mass Z-axis accelerometer embodiment of the present invention.

[0020] Fig.12 It is a front view schematic diagram of the arrangement relationship between the three-mass sensing structure and the compensation capacitor structure of the MEMS substrate structure of the three-mass Z-axis accelerometer embodiment of the present invention.

[0021] Fig.13 It is a front schematic diagram of an embodiment of a bow compensation capacitor structure of a MEMS substrate structure of an embodiment of a three-mass Z-axis accelerometer of the present invention.

[0022] Fig.14 It is a front schematic diagram of an embodiment of a bow compensation capacitor structure of a MEMS substrate structure of an embodiment of a three-mass Z-axis accelerometer of the present invention.

[0023] Fig.15 It is a front schematic diagram of a capacitor pair structure embodiment without compensation function of a MEMS substrate structure of a three-mass Z-axis accelerometer embodiment of the present invention.

[0024] Fig.16 It is a front schematic diagram of a capacitor pair structure embodiment without compensation function of a MEMS substrate structure of a three-mass Z-axis accelerometer embodiment of the present invention.

[0025] Fig.17 It is a front schematic diagram of a capacitor pair structure embodiment without compensation function of a MEMS substrate structure of a three-mass Z-axis accelerometer embodiment of the present invention.

[0026] Fig.18 It is a schematic cross-sectional view of part of the structure during the manufacturing process of the three-mass Z-axis accelerometer embodiment of the present invention.

[0027] Fig.19 It is a schematic cross-sectional view of part of the structure during the manufacturing process of the three-mass Z-axis accelerometer embodiment of the present invention.

[0028] Fig. 20 It is a schematic cross-sectional view of part of the structure during the manufacturing process of the three-mass Z-axis accelerometer embodiment of the present invention.

[0029] Fig.21 It is a schematic cross-sectional view of part of the structure during the manufacturing process of the three-mass Z-axis accelerometer embodiment of the present invention.

[0030] Fig. 22 It is a schematic cross-sectional view of part of the structure during the manufacturing process of the three-mass Z-axis accelerometer embodiment of the present invention.

[0031] Fig.23 It is a schematic cross-sectional view of part of the structure during the manufacturing process of the three-mass Z-axis accelerometer embodiment of the present invention.

[0032] Fig.24 It is a schematic cross-sectional view of part of the structure during the manufacturing process of the three-mass Z-axis accelerometer embodiment of the present invention.

[0033] Fig.25 It is a schematic cross-sectional view of part of the structure during the manufacturing process of the three-mass Z-axis accelerometer embodiment of the present invention.

[0034] Fig.26 It is a schematic cross-sectional view of part of the structure during the manufacturing process of the three-mass Z-axis accelerometer embodiment of the present invention.

[0035] Fig. 27 It is a schematic cross-sectional view of part of the structure during the manufacturing process of the three-mass Z-axis accelerometer embodiment of the present invention.

[0036] Description of Reference Numerals

[0037] 10CMOS substrate

[0038] 11 Key pad

[0039] 12 Solder pads

[0040] 13 Sensing electrode plate

[0041] 15 Conductive thread

[0042] 17 Conductive holes

[0043] 19CMOS body

[0044] 20MEMS substrate

[0045] 21 Electrical connection anchor structure

[0046] 22 Cap fixing anchor structure

[0047] 23MeMS sensing structure mass block

[0048] 23c First mass

[0049] 23b Second mass

[0050] 23a Third mass

[0051] 24 Retaining spring

[0052] 25 Bonding structure

[0053] 26 Electrical connection spring

[0054] 27 Hermetic Bonded Ring Structure

[0055] 28 Sensing spring

[0056] 30 Connection spring

[0057] 31 Hollow

[0058] 40 Cap substrate

[0059] 41 First block

[0060] 42 Second block top post

[0061] 49 Cap body

[0062] 60MEMS substrate

[0063] 61 Fixed anchor structure

[0064] 62 Second bow compensation capacitor structure

[0065] 64 First bow compensation capacitor structure

[0066] 65 Transition Structure

[0067] 66 first capacitor plate

[0068] 68 Second capacitor plate

[0069] 71 Three-mass sensing structure

[0070] 73 Three-mass sensing structure

[0071] 75 Three-mass sensing structure

[0072] 77 Three-mass sensing structure

[0073] 82 bow compensation capacitor structure

[0074] 84 bow compensation capacitor structure

[0075] 85 Transition Structure

[0076] 86 first capacitor plate

[0077] 88 Second capacitor plate

[0078] 91 bow compensation capacitor structure

[0079] 95 Transition Structure

[0080] 96 first capacitor plate

[0081] 97 Bow Compensation Capacitor Structure

[0082] 98 Second capacitor plate

[0083] Ca_1, Ca_2, Cb capacitors

[0084] Comp_Ca, Comp_Cb compensation capacitors

[0085] delta C capacitance change

[0086] BB' section line

[0087] X, Y, Z axis DETAILED DESCRIPTION

[0088] The following embodiments are illustrative. Although the following description refers to one, one or some embodiments, it does not mean that each such reference is to the same (same) embodiment, or that such features are only applicable to a single embodiment. Single features of different embodiments can be combined to provide other embodiments. The features of the present invention will be described below by simple examples of various implementation device architectures that can implement the present invention, and only the relevant elements for the examples will be described in detail. However, most of the implementation elements of the angular velocity sensor known to those skilled in the art may not be specifically described herein.

[0089] Figure 1 This is a side view of the first embodiment of the three-mass Z-axis accelerometer of the present invention. Figure 1The three-mass Z-axis accelerometer includes a complementary metal oxide semiconductor (CMOS) substrate 10, a microelectromechanical (MEMS) substrate 20 and a cap substrate 40 which are arranged parallel to each other and bonded to each other, wherein the MEMS substrate 20 is located between the CMOS substrate 10 and the cap substrate 40. The CMOS substrate 10 may include a CMOS body 19 and a CMOS circuit structure located on the surface of the CMOS body 19, wherein the CMOS circuit structure includes a number of conductive structures, such as conductive pads, conductive holes, etc., which can be used for electrical connection, electrical conduction or physical connection. In one embodiment, the CMOS circuit structure includes one or more bonding pads 11 that are physically in contact with and electrically connected to the MEMS substrate 20 and the cap substrate 40 that have been fused and bonded; the bonding pads 12 are exposed on the surface of the CMOS substrate 10 for connection with other structures; one or more sensing electrode plates 13 correspond to the MEMS substrate 20; and a plurality of conductive holes 17 that are physically in contact with and electrically connected to the conductive wire 15 and the bonding pads 11, and between the bonding pads 12 and the sensing electrode plates 13. Secondly, the cap substrate 40 may include a cap body 49 and a plurality of cap pillars protruding from the cap body 49 and facing the MEMS substrate 20. In one embodiment, one or more first cap pillars 41 correspond to the bonding pads 11 of the CMOS substrate 10 and are fixed and electrically connected to each other through the MEMS substrate 20, while the second cap pillars 42 are fixed to the MEMS substrate 20. The MEMS substrate 20 includes a plurality of mass blocks 23 of the MEMS sensing structure, a plurality of cap fixing anchor structures 22, a plurality of electrical connection anchor structures 21, and a bonding structure 25. The MEMS substrate 20 may be regarded as including a movable sensing structure, and the cap fixing anchor structure 22 connects and fixes the entire movable sensing structure with a sensing spring (to be described later), and is connected to the second cap pillar 42 of the cap substrate 40. The electrical connection anchor structure 21 is connected to the first cap pillar 41 of the cap substrate 40, and is in contact with, electrically connected and fixed to the bonding pad 11 of the CMOS substrate 10 through the bonding structure 25. To further illustrate, the first cap top pillar 41 around the cap substrate 40 surrounds the MEMS sensing structure of the MEMS substrate 20 to form a ring structure, and forms an airtight bonding ring structure 27 (bond ring) with the bonding pad 11 of the CMOS substrate 10 below (such as Figure 1 The MEMS sensing structure is operated in an airtight environment.

[0090] Figure 2 This is a front view of the first embodiment of the MEMS substrate structure of the three-mass Z-axis accelerometer embodiment of the present invention. Figure 1 and Figure 2 The mass block 23 of the MEMS sensing structure may further include a first mass block 23c, a second mass block 23b and a third mass block 23a, wherein Figure 2 The dotted line frame indicates the location of the sensing electrode plate 13 of the CMOS substrate 10 below the MEMS substrate 20, that is, the first mass block 23c, the second mass block 23b and the third mass block 23a correspond to the sensing electrode plate 13 of the CMOS substrate 10 respectively to form a capacitor structure. Secondly, the second mass block 23b is located between the first mass block 23c and the third mass block 23a, and the second mass block 23b is connected to the first mass block 23c and the third mass block 23a respectively through the connecting spring 30, wherein the first mass block 23c and the third mass block 23a can be respectively called seesaw mass blocks, and the second mass block 23b can be called a connecting mass block. The cap fixing anchor point structure 22 and the multiple electrical connection anchor point structures 21 are arranged in the hollow part 31 between the connecting spring 30 and the first mass block 23c and the third mass block 23a. Each cap fixing anchor structure 22 is connected to the entire movable sensing structure (MEMS substrate 20) through one or more sensing springs 28, or in other words, connected to the seesaw mass through the sensing springs 28, and includes one or more stop springs 24 extending toward the hollow portion 31. An electrical connection spring 26 is connected to the electrical connection anchor structure 21 and the cap fixing anchor structure 22 to electrically connect the two, and the electrical connection anchor structure 21 is electrically connected to the bonding pad 11 of the CMOS substrate 10 below through the bonding structure 25 below itself.

[0091] According to the above, the MEMS sensing structure has two anchoring structures, namely the electrical connection anchor structure 21 and the cap fixing anchor structure 22, which serve as a fixing structure and an electrical conduction structure respectively. Therefore, on the one hand, during the bonding process, the suspended cap fixing anchor structure 22 will not be damaged due to the bonding pressure, thereby reducing the risk of the cap fixing anchor structure 22 being torn. On the other hand, if the electrical connection anchor structure 21 is torn due to the bonding pressure, its electrical properties can still remain connected, and the stability of the sensing structure is not affected. Therefore, such a design can improve the process yield and stability of the product.

[0092] Figure 3 , Figure 4 and Figure 5 They are partial side schematic diagrams of the MEMS sensing structure of the three-mass Z-axis accelerometer embodiment of the present invention, wherein Figure 3 There is no force in the Z-axis direction. Figure 4 The Z axis is subjected to 1G force (acceleration force). Figure 5 The Z-axis is subjected to a -1G force. For the convenience of explanation, some structures are omitted here. The capacitance symbols (Ca_1, Ca_2, Cb) are marked below the circuit structure of the CMOS substrate. The Z-axis force direction is indicated by a solid single arrow above the MEMS substrate 20. The solid single arrow next to the capacitance symbol indicates the direction of capacitance change. Please also refer to Figures 1 to 5, the capacitance formed by the first mass block 23c and the sensing electrode plate 13 is represented by "Ca_1"; the capacitance formed by the second mass block 23b and the sensing electrode plate 13 is represented by "Cb"; and the capacitance formed by the third mass block 23a and the sensing electrode plate 13 is represented by "Ca_2". When the MEMS sensing structure is not subjected to the acceleration in the Z-axis direction, Cb is equal to Ca_1 plus Ca_2, and the capacitance change delta C (ΔC) is Ca_1 plus Ca_2 minus Cb, which is equal to 0. When the MEMS sensing structure is subjected to the earth's gravity acceleration or external acceleration, it produces inertial motion, and then twists the sensing spring 28 in the MEMS sensing structure to form a seesaw motion. The double seesaw structure formed by the three mass blocks in the present invention is linked to form an arch bridge-like motion, so the mass blocks on both sides form a seesaw tilting motion, and the middle mass block forms a parallel plate up and down motion. The mass blocks on both sides move in opposite directions to the middle mass block, and the capacitance change generated by the sensing electrode plate 13 of the CMOS substrate is also opposite, and the two form a differential capacitor pair. If the differential capacitor pair of the present invention is combined with an external ASIC (not shown) sensing circuit to form a differential sensing circuit, the capacitance change can be measured. Figure 1 and Figure 4 As shown, the MEMS sensing structure is subjected to the gravity acceleration or external acceleration of 1G in the Z-axis direction. When the second mass block 23b moves upward (positive Z) in parallel with the plate, the first mass block 23c and the third mass block 23a move downward in a tilted seesaw manner, and the part away from the second mass block 23b is close to the sensing electrode plate 13. At this time, the capacitances Ca_1 and Ca_2 increase, and Cb decreases, so delta C (ΔC) is greater than 0. Figure 1 and Figure 5 As shown, the MEMS sensing structure is subjected to the gravity acceleration or external acceleration of -1G in the Z-axis direction. When the second mass block 23b moves downward in parallel with the plate, the first mass block 23c and the third mass block 23a move upward in a tilted seesaw manner, and the part away from the second mass block 23b is away from the sensing electrode plate 13. At this time, the capacitances Ca_1 and Ca_2 decrease, and Cb increases, so delta C (ΔC) is less than 0. Therefore, when the MEMS sensing structure is subjected to inertial motion caused by the gravity acceleration of the earth or the external acceleration, the first mass block 23c, the second mass block 23b and the third mass block 23a are deformed to form an arch bridge pattern, wherein the deformation direction of the arch bridge pattern may be opposite due to different mass block weights. Figure 4 and Figure 5 This is only for illustration and is not intended to limit the present invention.

[0093] Figure 6 It is a front view of a second embodiment of the MEMS substrate structure of the three-mass Z-axis accelerometer embodiment of the present invention. Figure 7 for Figure 6Schematic diagram of the cross section along the BB' section line. Please refer to Figure 1 , Figure 2 , Figure 6 and Figure 7 , the MEMS substrate 60 includes Figure 2 In addition to the MEMS movable sensing structure, it also includes an arcuate compensation capacitor structure arranged around the first mass block 23c, the second mass block 23b and the third mass block 23c, such as a first arcuate compensation capacitor structure 64 and a second arcuate compensation capacitor structure 62 on both sides of the MEMS movable sensing structure, wherein the first arcuate compensation capacitor structure 64 and the second arcuate compensation capacitor structure 62 are also arranged in the airtight chamber of the airtight bonding ring structure 27 and the cap substrate 40 and the CMOS substrate 10 (such as Figure 1 ). The first bow-shaped compensation capacitor structure 64 and the second bow-shaped compensation capacitor structure 62 each include two bow-shaped structures symmetrically arranged, including four fixed anchoring structures 61 arranged oppositely, a first capacitor plate 66 connected to the two opposite fixed anchoring structures 61 through two turning structures 65, and a second capacitor plate 68 is arranged relative to the first capacitor plate 66 and connected to the first capacitor plate 66 at the middle position. For the convenience of explanation, from the first capacitor plate 66 connected to the turning structure 65, the first bow-shaped compensation capacitor structure 64 adjacent to the first capacitor plate 66 can be called a face-to-face type, and the second bow-shaped compensation capacitor structure 62 with the second capacitor plate 68 between the first capacitor plates 66 is called a back-to-back type. Generally speaking, the MEMS sensing structure is deformed by stress, which may cause zero-gravity acceleration (0G) level shift, wherein the source of stress includes packaging residual stress, upper welding residual stress, finished product assembly stress or ambient temperature change, etc. When the chip is deformed by external stress, the distance between the sensing structure and the sensing electrode will change, resulting in a change in capacitance. Therefore, the deformation caused by the above stress can be reduced by designing a compensation capacitor. Secondly, the design of the turning structure 65, such as a buckling structure, can amplify the strain and increase the compensation range.

[0094] Figure 8 This is a front view of the compensation capacitor structure of the second embodiment of the MEMS substrate structure of the three-mass Z-axis accelerometer embodiment of the present invention. Figure 1 , Figure 2 , Figure 6 , Figure 7 and Figure 8, each pair of first capacitor plates 66 and second capacitor plates 68 constitute an arch capacitor structure that is bonded to the MEMS substrate 60 through two fixed anchor structures 61 at both ends in the long axis direction. The arch capacitor itself has no mass block, so the arch capacitor does not deform due to gravity, but it will deform due to the stress between the two fixed anchor structures 61. If the MEMS substrate 60 is subjected to the tensile stress F in the Y direction, the first arch compensation capacitor structure 64 (face-to-face type) will be stretched and deformed in the X direction (as indicated by the simple arrow below the MEMS substrate 60), that is, the first arch compensation capacitor structure 64 is pulled by the tensile stress in the Y direction, so that the distance between the two arch plates of the first arch compensation capacitor structure 64 increases, thereby reducing the first compensation capacitor "Comp_Ca" of the first arch compensation capacitor structure 64. In contrast, the second bow-shaped compensation capacitor structure 62 (back-to-back type) will be compressed and deformed in the X direction (as indicated by the simple arrow below the MEMS substrate 60), that is, the spacing between the two bow-shaped plates of the second bow-shaped compensation capacitor structure 62 is reduced as the tensile stress in the Y direction pulls, thereby increasing the second compensation capacitor "Comp_Cb" of the second bow-shaped compensation capacitor structure 62. It can be understood that if the MEMS substrate 60 is subjected to compressive stress in the Y direction, the two first capacitor plates 66 (bow-shaped capacitor plates) in the first bow-shaped compensation capacitor structure 64 (face-to-face type) each produce compressive buckling deformation in the X direction. Due to the face-to-face arrangement, the spacing between the first capacitor plates 66 becomes smaller, thereby increasing the first compensation capacitor "Comp_Ca" of the first bow-shaped compensation capacitor structure 64; in contrast, the two first capacitor plates 66 (bow-shaped capacitor plates) in the second bow-shaped compensation capacitor structure 62 (back-to-back type) each produce tensile deformation in the X direction. Due to the back-to-back arrangement, the spacing between the first capacitor plates 66 becomes larger, thereby reducing the second compensation capacitance "Comp_Cb" of the second bow-shaped compensation capacitor structure 62. Therefore, for the bow-shaped compensation capacitor structure, the two bow-shaped buckling structures can form two types of capacitor pairs after being arranged symmetrically on the left and right. It is defined that when they are compressed and buckled, they are deformed in the direction of the symmetry axis at the same time to form a positive compensation capacitor pair (the capacitor plates are close to each other and the capacitance increases, such as the face-to-face type of the first bow-shaped compensation capacitor structure 64), and vice versa, it is a reverse compensation capacitor pair (such as the back-to-back type of the second bow-shaped compensation capacitor structure 62). Therefore, the MEMS substrate of the present invention can eliminate the offset phenomenon of the zero-gravity acceleration (0G) level caused by various stress influences by adding the setting of the bow-shaped compensation capacitor structure. It can include both face-to-face type and back-to-back type. The setting method can be as follows Figure 6 For example, the long axis of the first bow-shaped compensation capacitor structure 64 is substantially parallel to the long axis of the second bow-shaped compensation capacitor structure 62, and is also parallel to the long axes of the first mass block 23c, the second mass block 23b and the third mass block 23a.

[0095] Fig. 9 , Fig.10 , Fig.11 and Fig.12 The front view schematic diagrams of the three-mass sensing structure and the compensation capacitor structure of the MEMS substrate structure of the three-mass Z-axis accelerometer embodiment of the present invention are respectively shown. For the convenience of explanation, only the positional relationship between the three-mass sensing structure and the bow-shaped compensation capacitor structure of the MEMS substrate is shown in the figure, and the remaining structures may be omitted and not repeated. Fig. 9 , the three-mass sensing structure 71 at least includes a MEMS sensing structure composed of a first mass 23c, a second mass 23b, and a third mass 23a and a COM substrate structure thereunder. Secondly, the first bow-shaped compensation capacitor structure 64 and the second bow-shaped compensation capacitor structure 62 are respectively arranged on the upper and lower sides of the three-mass sensing structure 71 (as viewed from the figure). and Figure 6 In comparison, Fig. 9 The long axis direction of the first bow-shaped compensation capacitor structure 64 and the second bow-shaped compensation capacitor structure 62 is the X direction, and the long axis direction of the first mass block 23c, the second mass block 23b and the third mass block 23a is the Y direction, that is, the long axis of the compensation capacitor structure is perpendicular to each mass block of the sensing structure. Fig.10 , the long axis direction of the first mass block 23c, the second mass block 23b and the third mass block 23a of the three-mass-block sensing structure 73 is the Y direction, the first bow-shaped compensation capacitor structure 64 and the second bow-shaped compensation capacitor structure 62 are respectively arranged on an adjacent long side and a short side of the three-mass-block sensing structure 73, the long axis direction of the first bow-shaped compensation capacitor structure 64 is the Y direction, and the long axis direction of the second bow-shaped compensation capacitor structure 62 is the X direction, so the long axis direction of the second bow-shaped compensation capacitor structure 62 is perpendicular to the long axis direction of the first mass block 23c, the second mass block 23b and the third mass block 23a. Reference Fig.11 , four sides of the three-mass sensing structure 75 are provided with four bow-shaped compensation capacitor structures, wherein adjacent long sides and short sides are respectively provided with a first bow-shaped compensation capacitor structure 64, and another pair of adjacent long sides and short sides are respectively provided with a second bow-shaped compensation capacitor structure 62. Fig.12 , a bow-shaped compensation capacitor structure is respectively arranged at the four corners of the three-mass sensing structure 77, wherein two corners of one short side are respectively arranged with a first bow-shaped compensation capacitor structure 64; and two corners of another short side are respectively arranged with a second bow-shaped compensation capacitor structure 62. Therefore, one or more bow-shaped compensation capacitor structures can be arranged near the three-mass sensing structure of the three-mass Z-axis accelerometer of the present invention, so as to eliminate the deformation caused by the influence of stress.

[0096] Fig.13 and Fig.14 They are front views of the MEMS substrate structure of the bow compensation capacitor structure of the three-mass Z-axis accelerometer embodiment of the present invention. Fig.13The arcuate compensation capacitor structure 82 is a back-to-back type and includes a forward compensation capacitor pair, wherein the first capacitor plate 86 is an arc-shaped capacitor plate, the turning structure 85 connected to the first capacitor plate 86 is a straight line, and the second capacitor plate 88 is a flat plate. This state is to amplify the strain through the arc-shaped capacitor plate. Fig.14 The bow-shaped compensation capacitor structure 84 is of a back-to-back type and includes a reverse compensation capacitor pair, wherein the first capacitor plate 86 is an arc-shaped capacitor plate, the turning structure 85 connected to the first capacitor plate 86 is a straight line, and the second capacitor plate 88 is a flat plate, and the strain is also amplified through the arc-shaped capacitor plate. Therefore, the sensitivity of the bow-shaped buckling structure included in the bow-shaped compensation capacitor structure to stress can be adjusted by the width and / or length of the buckling structure, the turning angle of the buckling structure, or the starting distance between a pair of bow-shaped buckling structures. The bow-shaped compensation capacitor structure of the present invention achieves the structural strain generated by the amplification of stress through the turning structure or the geometric shape design of the capacitor plate or at least one of the two.

[0097] Fig.15 , Fig.16 and Fig.17 The front views of the capacitor pair structure embodiments of the three-mass Z-axis accelerometer of the present invention are schematic diagrams of the MEMS substrate structure without compensation function. In some cases, the MEMS sensing structure can also be configured with a virtual compensation structure without sensitivity. This virtual compensation structure is only used to form a symmetrical and equal capacitance size, such as maximizing the width of the buckling structure to reduce buckling deformation, or setting multiple turning structures to reduce buckling lateral deformation, etc. Fig.15 The bow-shaped compensation capacitor structure 91 is a back-to-back type, wherein the first capacitor plate 96 and the second capacitor plate 98 are both flat plates, and the turning structure 95 includes four right-angle corner structures. Fig.16 The bow-shaped compensation capacitor structure 93 is of a face-to-face type, wherein the first capacitor plate 96 and the second capacitor plate 98 are both flat plates, and the turning structure 95 also includes four right-angle corner structures. Fig.17 The bow-shaped compensation capacitor structure 97 is of a back-to-back type, wherein the first capacitor plate 96 and the second capacitor plate 98 are both flat plates without a turning structure, and the width of the first capacitor plate 96 is maximized.

[0098] Figures 18 to 27 This is a schematic cross-sectional view of the manufacturing process of the three-mass Z-axis accelerometer embodiment of the present invention. Figure 1 , Fig.18 and Fig.19 A cap body 49 is provided and a first cap top column 41 and a second cap top column 42 are formed on the surface of the cap body 49 through common patterning steps, such as photolithography, exposure, development and etching, wherein the outermost first cap top column 41 is a ring structure. Figure 1, Fig. 20 and Fig.21 The original MEMS substrate 20 (original substrate) is bonded to the patterned cap body 49 in an appropriate manner, such as fusion bonding, and the original MEMS substrate 20 is thinned. Figure 1 , Fig. 22 , Fig.23 and Fig.24 The thinned MEMS substrate 20 is deposited and patterned in an appropriate manner to form a bonding structure 25, and then a MEMS sensing structure including an electrical connection anchor structure 21, a cap fixing anchor structure 22, a mass block, a connection spring, a sensing spring, and a stop spring is formed. Figure 1 , Fig.25 and Fig.26 The CMOS substrate is formed into a circuit layer on the CMOS body 19 in a conventional manner, and a number of conductive pads, connection pads, electrode plates, etc. on the surface are exposed by appropriate etching. Figure 1 , Fig.24 and Fig. 27 , in an appropriate manner, such as eutectic bonding, the combination of the MEMS substrate and the cap substrate 40 is overlaid on the CMOS substrate 10 to bond the two together. If necessary, the cap substrate 40 is thinned and the cap substrate 40 and the MEMS substrate 20 are cut (sawed) to obtain the three-mass Z-axis accelerometer of the present invention.

[0099] The embodiments described above are only for illustrating the technical ideas and features of the present invention, and their purpose is to enable people skilled in the art to understand the contents of the present invention and implement them accordingly. They cannot be used to limit the patent scope of the present invention. That is, all equivalent changes or modifications made according to the spirit disclosed by the present invention should still be included in the patent scope of the present invention.

Claims

1. A three-mass Z-axis accelerometer, comprising a complementary metal oxide semiconductor substrate, a micro-electromechanical substrate and a cap substrate arranged in parallel and bonded to each other, characterized in that: The micro-electromechanical substrate comprises: Two seesaw masses; A connecting mass block is disposed between the two seesaw mass blocks and is connected to the two seesaw mass blocks respectively through a plurality of connecting springs, and a hollow area is disposed between the connecting mass block and any of the seesaw mass blocks, wherein the connecting mass block and the two seesaw mass blocks respectively correspond to a plurality of sensing electrode plates on the complementary metal oxide semiconductor substrate to form a plurality of capacitor structures; A plurality of electrical connection anchor structures are respectively fixed to and electrically connected with the complementary metal oxide semiconductor substrate and the cap substrate, wherein any of the electrical connection anchor structures corresponds to fixing a first cap top pillar of the cap substrate and a bonding pad of the complementary metal oxide semiconductor substrate; and A plurality of cap fixing anchor structures are respectively fixedly connected to the cap substrate, wherein any of the cap fixing anchor structures corresponds to fixing a second cap top column of the cap substrate, and the plurality of electrical connection anchor structures and the plurality of cap fixing anchor structures are arranged in the plurality of hollow areas.

2. The three-mass Z-axis accelerometer according to claim 1, characterized in that: The plurality of cap fixing anchor point structures are connected to the plurality of seesaw mass blocks through a plurality of sensing springs and are connected to the plurality of electrical connection anchor point structures through a plurality of electrical connection springs. The plurality of sensing springs and the plurality of electrical connection springs are disposed in the plurality of hollow areas.

3. The three-mass Z-axis accelerometer according to claim 1, wherein: The micro-electromechanical substrate further includes a plurality of retaining springs connected to the plurality of cap fixing anchor point structures and arranged in the plurality of hollow areas.

4. The three-mass Z-axis accelerometer according to any one of claims 1 to 3, characterized in that: The micro-electromechanical substrate further includes a plurality of bow-shaped compensation capacitor structures disposed around the connection mass block and the plurality of seesaw mass blocks.

5. The three-mass Z-axis accelerometer of claim 4, wherein: Any of the bow-shaped compensation capacitor structures includes two bow-shaped structures symmetrically arranged, and any of the bow-shaped structures includes a first capacitor plate, and the two ends of the first capacitor plate are respectively connected to a fixed anchor structure through two buckling structures, and a second capacitor plate is connected to a middle section of the first capacitor plate.

6. The three-mass Z-axis accelerometer of claim 5, wherein: Any of the first capacitor plates is in an arc shape or a flat plate shape.

7. The three-mass Z-axis accelerometer of claim 5, wherein: The two second capacitor plates are located between the two first capacitor plates, or the two first capacitor plates are located between the two second capacitor plates.

8. The three-mass Z-axis accelerometer according to any one of claims 1 to 3, characterized in that: The micro-electromechanical substrate further comprises a plurality of bonding structures fixed between the plurality of electrical connection anchor structures and the plurality of bonding pads, so as to form an airtight bonding ring structure with the plurality of first cap top pillars around the cap substrate itself.

9. A method for manufacturing a three-mass Z-axis accelerometer as claimed in any one of claims 1 to 3, characterized in that: include: Providing the cap substrate including the plurality of first cap top pillars and the plurality of second cap top pillars; Melting and bonding an original substrate to the cap substrate; patterning the original substrate to form the micro-electromechanical substrate; Providing the complementary metal oxide semiconductor substrate including the plurality of bonding pads and the plurality of sensing electrode plates; as well as The metal eutectic bonds the micro-electromechanical system substrate and the complementary metal oxide semiconductor substrate.

10. A method for manufacturing a three-mass Z-axis accelerometer according to any one of claims 4 to 7, characterized in that: include: Providing the cap substrate including the plurality of first cap top pillars and the plurality of second cap top pillars; Melting and bonding an original substrate to the cap substrate; patterning the original substrate to form the micro-electromechanical substrate; Providing the complementary metal oxide semiconductor substrate including the plurality of bonding pads and the plurality of sensing electrode plates; as well as The metal eutectic bonds the micro-electromechanical system substrate and the complementary metal oxide semiconductor substrate.

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