MEMS inertial device and manufacturing process thereof

Abstract

The invention provides an MEMS inertial device and a manufacturing process thereof, and relates to the technical field of inertial devices.The device comprises a silicon substrate, a device layer, a wiring metal layer and an upper cover plate which are sequentially bonded from bottom to top, a plurality of bonding pads are arranged on the upper side of the upper cover plate, and a plurality of through holes corresponding to the bonding pads are formed in the upper cover plate; the wiring metal layer is electrically connected with the plurality of bonding pads through the plurality of through holes. According to the invention, the metal wiring layer does not go through the substrate, but goes through the device layer, and leads out signals from the cover plate, thereby avoiding the complex technological process caused by going through the substrate, and reducing the technological difficulty of the MEMS inertial device. Moreover, the wiring metal layer is arranged between the cover plate and the device layer, can be used as a solder ring to connect the cover plate and the device layer, and can also be used for signal connection, so that the size of the MEMS inertial device can be reduced, and the cost of the MEMS inertial device can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of inertial devices, and in particular to a MEMS inertial device and a manufacturing process thereof. Background Art

[0002] MEMS inertial devices are widely used in inertial navigation, drones, autonomous driving, intelligent manufacturing, and high-end industrial fields. In existing technologies, the metal traces of MEMS inertial devices are all completed on a silicon substrate. A metal trace layer is grown on the silicon substrate, allowing the electrical signals from the inertial device layer to be transmitted through this metal trace layer to the ASIC circuit, ultimately achieving MEMS inertial device detection. In existing inertial device structures, the metal traces are all completed on a silicon substrate, resulting in a complex process flow, increasing process difficulty and reducing process yield. This also results in high costs, large device area, and high space requirements, making it difficult to miniaturize. Summary of the Invention

[0003] The purpose of the present invention is to provide a MEMS inertial device and a manufacturing process thereof, aiming to reduce the manufacturing difficulty and cost of MEMS inertial devices. The specific technical solution is as follows:

[0004] A MEMS inertial device includes a silicon substrate, a device layer, a routing metal layer, and an upper cover plate bonded sequentially from bottom to top. The upper side of the upper cover plate is provided with multiple solder pads. The upper cover plate is also provided with multiple through holes corresponding to the multiple solder pads, and the routing metal layer is electrically connected to the multiple solder pads through the multiple through holes.

[0005] Furthermore, the silicon substrate and the device layer are bonded via a solder ring.

[0006] Furthermore, the device layer includes a mass block, a movable comb tooth anchor column, movable comb teeth, fixed comb teeth, and a beam structure, and the movable comb tooth anchor column is bonded to the solder ring; fixed comb tooth anchor columns are also etched on the silicon substrate, and the mass block is supported on the middle part of the silicon substrate through the fixed comb tooth anchor columns; the routing metal layer is bonded to the movable comb tooth anchor columns.

[0007] Furthermore, the fixed comb teeth are distributed around the mass block, the movable comb teeth are distributed around the beam structure, and the movable comb tooth anchor column is connected to the movable comb teeth through the beam structure, so that the movable comb teeth are suspended above the silicon substrate, and the beam structure is suspended between the movable comb tooth anchor column and the movable comb teeth, and surrounds the mass block within the movable comb tooth anchor column.

[0008] Furthermore, the frame edge of the movable comb tooth anchor column is 10um to 50um wider than the frame edge of the solder ring.

[0009] Furthermore, the routing metal layer is arranged on the lower side of the upper cover plate, and the upper cover plate fixed comb tooth anchor column is also arranged on the lower side of the upper cover plate, the routing metal layer surrounds the upper cover plate fixed comb tooth anchor column, the routing metal layer covers the multiple through holes on the outside, the upper cover plate fixed comb tooth anchor column covers the through hole in the center, and the mass block is bonded to the upper cover plate fixed comb tooth anchor column.

[0010] Furthermore, the routing metal layer is consistent in shape and size with the solder ring and the movable comb tooth anchor column, and is in a square frame shape. The upper cover plate fixed comb tooth anchor column is consistent in shape and size with the fixed comb tooth anchor column.

[0011] Furthermore, the beam structure includes a square frame and four straight beams connecting the square frame and corresponding sides of the movable comb anchor column.

[0012] Furthermore, three soldering pads are provided and arranged in a straight line on the upper cover plate, two of which are located at the edge of the upper cover plate, and one is located at the center of the upper cover plate.

[0013] The present invention also provides a manufacturing process for a MEMS inertial device, which is used to manufacture the MEMS inertial device as described above, comprising the following steps:

[0014] S100, etching the silicon substrate to form the solder ring and the fixed comb tooth anchor column; bonding the device layer, and etching to form the mass block, the movable comb tooth anchor column, the movable comb teeth, the fixed comb teeth, and the beam structure;

[0015] S200, growing the pad on the upper side of the upper cover wafer; growing a layer of SiO2 on the lower side of the upper cover wafer, etching the through hole, and filling it with metal to connect to the pad; growing routing metal on the lower side of the SiO2 layer, etching the routing metal to form the routing metal layer and the upper cover fixed comb anchor column;

[0016] S300 , bonding the upper cover plate, the device layer, and the silicon substrate to form a MEMS inertial device.

[0017] The present invention provides a MEMS inertial device and a manufacturing process thereof, which has the following beneficial effects:

[0018] The present invention provides a bonding device layer on a silicon substrate; a plurality of pads are provided on the upper side of an upper cover plate; a plurality of through holes are opened on the upper cover plate, respectively corresponding to the plurality of pads; the through holes are filled with metal to electrically connect with the pads; a routing metal layer is provided on the lower side of the upper cover plate; the routing metal layer covers at least part of the plurality of through holes; the upper cover plate is bonded to the device layer via the routing metal layer; the metal routing layer does not run on the substrate, but on the device layer, and the signal is led out of the cover plate, thereby avoiding the complex process flow caused by running on the substrate, and reducing the process difficulty of the MEMS inertial device; and the routing metal layer is between the cover plate and the device layer, and can be used as a solder ring to connect the cover plate and the device layer, and can also be used for signal connection, thereby reducing the volume of the MEMS inertial device and reducing the cost of the MEMS inertial device. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the MEMS inertial device provided by the present invention;

[0020] Figure 2 Schematic diagram of the structure of the silicon substrate of the present invention;

[0021] Figure 3 It is a schematic structural diagram of the silicon substrate bonding device layer of the present invention;

[0022] Figure 4 This is a structural diagram of the upper side of the upper cover plate of the present invention;

[0023] Figure 5 It is a partial structural schematic diagram of the lower side of the upper cover plate of the present invention;

[0024] Figure 6 It is a structural schematic diagram of the lower side of the upper cover plate of the present invention;

[0025] Figure 7 1 is a schematic diagram of the first step of the TSV process for the MEMS inertial device of the present invention;

[0026] Figure 8 1 is a schematic diagram of the second step of the TSV process for the MEMS inertial device of the present invention;

[0027] Figure 9 3 is a schematic diagram of the third step of the TSV process for the MEMS inertial device of the present invention. DETAILED DESCRIPTION

[0028] The following will be combined with the accompanying drawings provided by the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are all in a very simplified form and are not in exact proportions. They are only used to facilitate and clearly illustrate the purpose of the embodiments of the present invention.

[0029] Example 1: This example provides a MEMS inertial device 10, see Figure 1 As shown, it includes a silicon substrate 100, a device layer 200, a wiring metal layer 330 and an upper cover plate 300 bonded sequentially from bottom to top.

[0030] See Figure 2 As shown, a solder ring 110 and fixed comb anchors 120 are etched on a silicon substrate 100. In a preferred embodiment, the silicon substrate 100 is square, and the solder ring 110 is a square frame aligned with the edge of the silicon substrate 100. The fixed comb anchors 120 are cylindrical.

[0031] See Figure 3 As shown, a device layer 200 is bonded on a silicon substrate 100 , and the device layer 200 includes a mass block 210 , a movable comb anchor column 220 , movable comb teeth 230 , fixed comb teeth 240 , and a beam structure 250 .

[0032] The movable comb anchor 220 is bonded to the solder ring 110. In a preferred embodiment, the movable comb anchor is in a square frame shape, and the frame edge of the movable comb anchor is 10um to 50um wider than the frame edge of the solder ring to prevent metal overflow after bonding.

[0033] The mass block 210 is supported on the middle portion of the silicon substrate 100 via the fixed comb anchors 120. In a preferred embodiment, the mass block 210 is square.

[0034] The fixed comb teeth 240 are distributed around the mass block 210, and the dynamic comb teeth 230 are distributed around the beam structure 250. In one embodiment, the dynamic comb teeth 230 correspond to the fixed comb teeth 240 one by one.

[0035] The movable comb tooth anchor post 220 is connected to the movable comb tooth 230 via a beam structure 250, so that the movable comb tooth 230 is suspended above the silicon substrate 100. The beam structure 250 is suspended between the movable comb tooth anchor post 220 and the movable comb tooth 230, and surrounds the mass 210 within the movable comb tooth anchor post 220. In this embodiment, the device layer uses a solder ring as an anchor point and the beam connects the device structure to a suspended state, effectively reducing device stress and improving performance indicators.

[0036] In a preferred embodiment, the beam structure 250 includes a square frame and four straight beams connecting the square frame with corresponding sides of the movable comb anchor column 220. Optionally, the beam structure 250 can be a straight beam structure as shown in the figure, or a U-shaped beam or an L-shaped beam.

[0037] See Figure 4-6 As shown, a plurality of pads 310 are provided on the upper side of the upper cover 300. In a preferred embodiment, three square pads 310 are provided and arranged in a straight line on the upper cover 300, two of which are located at the edge of the upper cover 300 and one is located at the center of the upper cover 300.

[0038] The upper cover plate 300 is further provided with a plurality of through holes 320 corresponding to the plurality of pads 310. The plurality of through holes 320 are filled with metal to electrically connect to the plurality of pads 310. In a preferred embodiment, the through holes 320 are square in shape.

[0039] The lower side of the upper cover 300 is provided with a routing metal layer 330 and a fixed comb anchor post 340. The routing metal layer surrounds the fixed comb anchor post, with the routing metal layer 330 covering the outer plurality of through-holes 320 and the fixed comb anchor post 340 covering the central through-hole 320. In a preferred embodiment, the routing metal layer 330, the solder ring 110, and the movable comb anchor post 220 are of the same shape and size, forming a square frame. The fixed comb anchor post 340 is of the same shape and size as the fixed comb anchor post 120.

[0040] See Figure 1 As shown, the upper cover plate 300 is bonded to the device layer 200 and the silicon substrate 100 to form a MEMS inertial device, and the upper cover plate 300 and the device layer 200 are bonded to the movable comb tooth anchor column 220 through the routing metal layer 330 serving as the bonding ring of the upper cover plate 300, and the mass block 210 is bonded to the fixed comb tooth anchor column 340 of the upper cover plate.

[0041] Embodiment 2: This embodiment provides a manufacturing process for a MEMS inertial device, which is used to manufacture the MEMS inertial device 10 as described above, and includes the following steps:

[0042] S100, see Figure 7 As shown, a solder ring 110 and a fixed comb tooth anchor column 120 are etched on a silicon substrate 100 ; a bonding device layer 200 is bonded, and etching is performed to form a mass block 210 , a movable comb tooth anchor column 220 , movable comb teeth 230 , fixed comb teeth 240 , and a beam structure 250 .

[0043] S200, see Figure 8 As shown, a pad (PAD) 310 is grown on the upper side of a wafer (CAP) 300. A layer of SiO2 is grown on the lower side of the wafer, through-hole vias (TSVs) 320 are etched, and then filled with metal to connect to the pad 310. A trace metal layer is grown on the lower side of the SiO2 layer and etched to form a trace metal layer 330 and a top cover fixed comb anchor 340. In this embodiment, a TSV process is used to directly introduce electrical signals into the top layer of the device, simplifying the process steps.

[0044] S300, see Figure 9 As shown, the upper cover plate 300 is bonded to the device layer 200 and the silicon substrate 100 to form the MEMS inertial device 10 .

[0045] It should be noted that there is no order between steps S100 and S200.

[0046] Those skilled in the art should understand that the present invention can be implemented in many other specific forms without departing from the spirit and scope of the present invention. Based on the embodiments of the present invention, any changes and modifications made by ordinary technicians in the field of the present invention in accordance with the above disclosure are within the scope of protection of the claims.

Claims

1. A MEMS inertial device, characterized in that: It includes a silicon substrate, a device layer, a routing metal layer and an upper cover plate bonded in sequence from bottom to top, a plurality of pads are arranged on the upper side of the upper cover plate, and a plurality of through holes corresponding to the plurality of pads are also opened on the upper cover plate, and the routing metal layer is electrically connected to the plurality of pads through the plurality of through holes.

2. The MEMS inertial device according to claim 1, characterized in that: The silicon substrate and the device layer are bonded via a solder ring.

3. The MEMS inertial device according to claim 2, characterized in that: The device layer includes a mass block, a movable comb tooth anchor column, movable comb teeth, fixed comb teeth, and a beam structure, wherein the movable comb tooth anchor column is bonded to a solder ring; fixed comb tooth anchor columns are also etched on the silicon substrate, and the mass block is supported on the middle part of the silicon substrate through the fixed comb tooth anchor columns; the routing metal layer is bonded to the movable comb tooth anchor columns.

4. The MEMS inertial device according to claim 3, characterized in that: The fixed comb teeth are distributed around the mass block, the movable comb teeth are distributed around the beam structure, the movable comb tooth anchor column is connected to the movable comb teeth through the beam structure, so that the movable comb teeth are suspended above the silicon substrate, and the beam structure is suspended between the movable comb tooth anchor column and the movable comb teeth, and surrounds the mass block within the movable comb tooth anchor column.

5. The MEMS inertial device according to claim 3, characterized in that: The frame edge of the movable comb tooth anchor column is 10um to 50um wider than the frame edge of the solder ring.

6. The MEMS inertial device according to claim 3, characterized in that: The routing metal layer is arranged on the lower side of the upper cover plate, and an upper cover plate fixed comb tooth anchor column is also arranged on the lower side of the upper cover plate. The routing metal layer surrounds the upper cover plate fixed comb tooth anchor column, and the routing metal layer covers the multiple through holes on the outside. The upper cover plate fixed comb tooth anchor column covers the through hole in the center, and the mass block is bonded to the upper cover plate fixed comb tooth anchor column.

7. The MEMS inertial device according to claim 3, characterized in that: The routing metal layer is consistent in shape and size with the solder ring and the movable comb tooth anchor column, and is in a square frame shape. The upper cover plate fixed comb tooth anchor column is consistent in shape and size with the fixed comb tooth anchor column.

8. The MEMS inertial device according to claim 7, characterized in that: The beam structure includes a square frame and four straight beams connecting the square frame and corresponding sides of the movable comb anchor column.

9. The MEMS inertial device according to claim 6, characterized in that: Three soldering pads are provided and arranged in a straight line on the upper cover plate, two of which are located at the edge of the upper cover plate, and one is located at the center of the upper cover plate.

10. A manufacturing process for a MEMS inertial device, for manufacturing the MEMS inertial device according to any one of claims 1 to 9, comprising the following steps: S100, etching the silicon substrate to form the solder ring and the fixed comb tooth anchor column; bonding the device layer, and etching to form the mass block, the movable comb tooth anchor column, the movable comb teeth, the fixed comb teeth, and the beam structure; S200, growing the pad on the upper side of the upper cover wafer; growing a layer of SiO2 on the lower side of the upper cover wafer, etching the through hole, and filling it with metal to connect to the pad; growing routing metal on the lower side of the SiO2 layer, etching the routing metal to form the routing metal layer and the upper cover fixed comb anchor column; S300 , bonding the upper cover plate, the device layer, and the silicon substrate to form a MEMS inertial device.

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