CN215288001U

CN215288001U - MEMS sensor

Info

Publication number: CN215288001U
Application number: CN202120171377.9U
Authority: CN
Inventors: 宋亚伟; 迟海; 宋学谦
Original assignee: Hangzhou Hikmicro Sensing Technology Co Ltd
Current assignee: Hangzhou Hikmicro Sensing Technology Co Ltd
Priority date: 2021-01-21
Filing date: 2021-01-21
Publication date: 2021-12-24
Anticipated expiration: 2031-01-21

Abstract

The utility model provides a MEMS sensor, MEMS sensor includes: a substrate and a cover plate; the substrate comprises a MEMS structure, a first welding area arranged around the MEMS structure, and a first welding ring positioned on the first welding area; the cover plate comprises a second welding area and a second welding ring positioned at the second welding area; the substrate and the cover plate are welded together through the first welding ring and the second welding ring to form a sealing structure, so that the MEMS structure is limited in the vacuum cavity; at least one of the first welding area and the second welding area is provided with an annular groove or an annular bulge distributed along the circumferential direction, the first welding ring is conformally positioned on the first welding area, and the second welding ring is conformally positioned on the second welding area. According to the utility model discloses an embodiment, can reduce gaseous leak rate, improve MEMS sensor's reliability and life-span.

Description

MEMS sensor

Technical Field

The utility model relates to a semiconductor device technical field especially relates to a MEMS sensor.

Background

Hermetic packaging is a common form of packaging requirement in the MEMS field. MEMS devices, such as acceleration sensors, pressure sensors, angular velocity sensors, etc., have movable components inside, and it is necessary to provide an airtight cavity for the movable components to ensure that the movable components have small damping and static friction inside the cavity. The MEMS device such as an uncooled infrared focal plane detector is internally provided with a microbolometer, and the vacuum degree in the device needs to be reduced so as to ensure smaller heat radiation heat loss. When the air pressure in the cavity is increased to a vacuum degree exceeding a set standard, the sensitivity of the device is reduced to be below a standard value, and the device is failed. Thus, hermetic sealing is a critical factor in determining the lifetime of the device.

SUMMERY OF THE UTILITY MODEL

The utility model discloses a utility model aims at providing a MEMS sensor to solve not enough among the correlation technique.

To achieve the above object, the present invention provides a MEMS sensor, including:

a substrate including a MEMS structure, a first bond pad disposed around the MEMS structure, and a first bond ring at the first bond pad;

a cover plate including a second welding area and a second welding ring at the second welding area; the substrate and the cover plate are welded together through the first welding ring and the second welding ring to form a sealing structure so as to limit the MEMS structure in a vacuum cavity; at least one of the first weld zone and the second weld zone has circumferentially distributed annular grooves or annular protrusions, the first weld ring is conformally located on the first weld zone, and the second weld ring is conformally located on the second weld zone.

Optionally, the first weld zone has circumferentially distributed annular grooves and the second weld zone has circumferentially distributed annular projections, the annular grooves and the annular projections engaging the first weld ring with the second weld ring; or the first welding zone has annular protrusions distributed along the circumferential direction, the second welding zone has annular grooves distributed along the circumferential direction, and the annular protrusions and the annular grooves enable the first welding ring and the second welding ring to be meshed; or the first welding area is provided with annular grooves or annular bulges distributed along the circumferential direction, and the second welding area is a plane; or the first welding area is a plane, and the second welding area is provided with annular grooves or annular bulges distributed along the circumferential direction.

Optionally, the annular groove or the annular protrusion comprises two or more turns.

Optionally, the size of each ring of the annular groove or each ring of the annular protrusion is the same or different.

Optionally, a cross section of the annular groove or the annular protrusion along a direction perpendicular to the circumferential direction is triangular, square, rectangular, regular trapezoid or inverted trapezoid.

Optionally, a ratio between a depth of the annular groove and a width of the annular groove is greater than 1/10; or the ratio between the height of the annular projection and the width of the annular projection is greater than 1/10.

Optionally, the first weld ring sequentially includes, toward the cover plate direction: a first adhesive layer, a first barrier layer and a first wetting layer; and/or the second welding ring sequentially comprises towards the substrate direction: a second adhesion layer, a second barrier layer, and a second wetting layer.

Optionally, the material of the first adhesion layer and/or the second adhesion layer is titanium or chromium, the material of the first barrier layer and/or the second barrier layer is nickel, and the material of the first wetting layer and/or the second wetting layer is gold.

Optionally, the first bonding region has at least one of a first dielectric layer, a first passivation layer or a first semiconductor layer, the annular groove is located in the first dielectric layer, the first passivation layer or the first semiconductor layer, or the annular protrusion is made of the first dielectric layer, the first passivation layer or the first semiconductor layer; or the second welding area is provided with at least one of a second dielectric layer, a second passivation layer or a second semiconductor layer, the annular groove is positioned in the second dielectric layer, the second passivation layer or the second semiconductor layer, or the annular bulge is made of the second dielectric layer, the second passivation layer or the second semiconductor layer.

Optionally, the first and second solder rings are soldered together by an indium-based solder or a tin-based solder.

As described in the background, the device will fail when the air pressure inside the cavity rises to a vacuum level that exceeds a set level. The inventor analyzes the process of the air pressure increase in the cavity and finds that: because the solder and the interface have defects, the vacuum cavity cannot be absolutely sealed, and the leakage rate depends on the length of the gas channel according to the molecular gas conduction theory.

Based on the above analysis, the utility model provides a MEMS sensor, include: a substrate and a cover plate; the substrate comprises a MEMS structure, a first welding area arranged around the MEMS structure, and a first welding ring positioned on the first welding area; the cover plate comprises a second welding area and a second welding ring positioned at the second welding area; the substrate and the cover plate are welded together through the first welding ring and the second welding ring to form a sealing structure, so that the MEMS structure is limited in the vacuum cavity; at least one of the first welding area and the second welding area is provided with an annular groove or an annular bulge distributed along the circumferential direction, the first welding ring is conformally positioned on the first welding area, and the second welding ring is conformally positioned on the second welding area.

Compared with the prior art, the beneficial effects of the utility model reside in that:

firstly, under the condition of the same width of the welding ring, the effective length of the gas leakage channel is increased by manufacturing the rugged structure through the annular groove and/or the annular bulge, so that the gas leakage rate can be reduced, and the reliability and the service life of the MEMS sensor are improved.

Secondly, the non-planar uneven structure can improve the shearing strength of the MEMS sensor, so that the impact resistance reliability is improved.

Drawings

Fig. 1 is a schematic cross-sectional structural view of a MEMS sensor according to a first embodiment of the present invention;

FIG. 2 is a schematic top view of the substrate with the first solder ring removed;

FIG. 3 is a schematic bottom view of the cover plate with the second weld ring removed;

fig. 4 is a flow chart of a method of fabricating a MEMS sensor according to a first embodiment of the present invention;

FIGS. 5-10 are schematic intermediate structures corresponding to the flow chart of FIG. 4;

fig. 11 is a schematic cross-sectional structure view of a partial structure of a MEMS sensor according to a second embodiment of the present invention;

fig. 12 is a schematic cross-sectional structure view of a partial structure of a MEMS sensor according to a third embodiment of the present invention;

fig. 13 is a schematic cross-sectional structure view of a MEMS sensor according to a fourth embodiment of the present invention;

fig. 14 is a schematic cross-sectional structure diagram of a MEMS sensor according to a fifth embodiment of the present invention.

To facilitate understanding of the invention, all reference numerals appearing in the invention are listed below:

MEMS

sensor

1, 2, 3, 4, 5 substrate 11

MEMS structure 110 first bonding pad 111

First weld ring 112 cover plate 12

Second land 121 second solder ring 122

Sealing structure 13 vacuum chamber 13a

Annular groove 14 annular projection 15

First passivation layer 113 second dielectric layer 123

First adhesion layer 112a first barrier layer 112b

First wetting layer 112c second adhesive layer 122a

Second barrier layer 122b second wetting layer 122c

Prefabricated substrate 11 'prefabricated cover plate 12'

Solder layer 16

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention more comprehensible, embodiments accompanied with figures are described in detail below.

Fig. 1 is a schematic cross-sectional structure diagram of a MEMS sensor according to a first embodiment of the present invention. FIG. 2 is a schematic top view of the substrate with the first solder ring removed; fig. 3 is a schematic bottom view of the cover plate with the second weld ring removed.

Referring to fig. 1 to 3, a MEMS sensor 1 according to the first embodiment includes:

a substrate 11 including a MEMS structure 110, a first bonding pad 111 disposed around the MEMS structure 110, and a first bonding ring 112 at the first bonding pad 111;

a cap plate 12 including a second welding region 121, and a second welding ring 122 at the second welding region 121; the substrate 11 and the cover plate 12 are welded together by the first welding ring 112 and the second welding ring 122 to form a sealing structure 13, so as to define the MEMS structure 110 in the vacuum cavity 13 a; the first weld zone 111 has circumferentially distributed annular recesses 14, the second weld zone 121 has circumferentially distributed annular projections 15, the first weld ring 112 is conformally located on the first weld zone 111, and the second weld ring 122 is conformally located on the second weld zone 121.

The substrate 11 may include a first semiconductor substrate on which the MEMS structure 110 is disposed. The MEMS structure 110 may depend on the type of MEMS sensor 1. For example, when the MEMS sensor 1 is an acceleration sensor, a pressure sensor, or an angular velocity sensor, the MEMS structure 110 may include a fixed electrode and a movable electrode. The movable electrode may be a cantilever beam supported at one end, or a cantilever beam supported at both ends. For another example, when the MEMS sensor 1 is an uncooled infrared focal plane detector, the MEMS structure 110 includes a photosensitive structure with an uncovered upper surface. The MEMS structure 110 is not limited in this embodiment, and only needs to be disposed in a vacuum environment.

In this embodiment, referring to fig. 1 and 2, the first bonding pad 111 has a first passivation layer 113. The annular groove 14 is located within the first passivation layer 113. The material of the first passivation layer 113 may be silicon nitride. In other embodiments, the first bonding pad 111 may have a first dielectric layer, and the annular groove 14 is located in the first dielectric layer. The material of the first dielectric layer may be silicon dioxide. Alternatively, the first land 111 may have a first semiconductor layer in which the annular groove 14 is located. The material of the first semiconductor layer can be doped polysilicon or a monocrystalline silicon substrate. Or, the annular groove 14 is located in a stacked structure of at least two layers of the first dielectric layer, the first passivation layer and the first semiconductor layer. The present embodiment does not limit the kind of material of the first land 111.

The cover plate 12 may include a second semiconductor substrate.

In this embodiment, referring to fig. 1 and 3, the second bonding pad 121 has a second dielectric layer 123. The material of the annular protrusion 15 is a second dielectric layer 123. The material of the second dielectric layer 123 may be silicon dioxide. In other embodiments, the second bonding region 121 may have a second passivation layer, and the material of the annular bump 15 is the second passivation layer. The material of the second passivation layer may be silicon nitride. Or, the second bonding region 121 may have a second semiconductor layer, and the material of the annular projection 15 is the second semiconductor layer. The material of the second semiconductor layer can be doped polycrystalline silicon or a monocrystalline silicon substrate. Or, the material of the annular protrusion 15 is in a stacked structure of at least two layers of the second dielectric layer, the second passivation layer and the second semiconductor layer. The present embodiment does not limit the kind of material of the second lands 121.

The material of the first solder ring 112 and the second solder ring 122 is metal, such as copper or aluminum. The first weld ring 112 conformally located on the first weld zone 111 means: the thickness of the first weld ring 112 is small, and the cross section of the annular recessed region surrounded by the surface of the first weld ring 112 remote from the first weld zone 111 in the vertical circumferential direction coincides with the shape of the cross section of the annular groove 14 in the vertical circumferential direction.

In other words, when the cross section of the annular groove 14 in the vertical circumferential direction is triangular, the cross section of the annular recessed region surrounded by the surface of the first weld ring 112 away from the first weld region 111 in the vertical circumferential direction is triangular. When the cross section of the annular groove 14 in the vertical circumferential direction is square, the cross section of the annular recessed region surrounded by the surface of the first solder ring 112 away from the first solder land 111 in the vertical circumferential direction is square. When the cross section of the annular groove 14 in the vertical circumferential direction is rectangular, the cross section of the annular recessed region surrounded by the surface of the first solder ring 112 away from the first solder land 111 in the vertical circumferential direction is rectangular (see fig. 1). When the cross section of the annular groove 14 in the vertical circumferential direction is a trapezoidal shape, the cross section of the annular recessed region surrounded by the surface of the first weld ring 112 away from the first weld region 111 in the vertical circumferential direction is a trapezoidal shape. When the cross section of the annular groove 14 in the vertical circumferential direction is an inverted trapezoid, the cross section of the annular recessed region surrounded by the surface of the first weld ring 112 away from the first weld region 111 in the vertical circumferential direction is an inverted trapezoid.

The second solder ring 122 conformally located on the second solder region 121 means that: the thickness of the second weld ring 122 is small, and the cross section of the annular projection region formed on the surface of the second weld ring 122 remote from the second weld zone 121 in the vertical circumferential direction coincides with the cross section of the annular projection 15 in the vertical circumferential direction.

In other words, when the cross section of the annular projection 15 in the vertical circumferential direction is triangular, the cross section of the annular projection region formed on the surface of the second weld ring 122 away from the second weld zone 121 in the vertical circumferential direction is triangular. When the cross section of the annular projection 15 in the vertical circumferential direction is square, the cross section of the annular projection region formed on the surface of the second weld ring 122 remote from the second weld region 121 in the vertical circumferential direction is square. When the cross section of the annular projection 15 in the vertical circumferential direction is rectangular, the cross section of the annular projection region formed on the surface of the second weld ring 122 remote from the second weld region 121 in the vertical circumferential direction is rectangular (see fig. 1). When the cross section of the annular projection 15 in the vertical circumferential direction is a regular trapezoid, the cross section in the vertical circumferential direction of the annular projection region formed on the surface of the second weld ring 122 remote from the second weld zone 121 is a regular trapezoid. When the cross section of the annular projection 15 in the vertical circumferential direction is an inverted trapezoid, the cross section in the vertical circumferential direction of the annular projection region formed on the surface of the second weld ring 122 remote from the second weld zone 121 is an inverted trapezoid.

Referring to fig. 1, the annular groove 14 and the annular protrusion 15 may engage the first weld ring 112 and the second weld ring 122. The shape and size of the solder layer (not shown) is matched to the mating surfaces of the first solder ring 112 and the second solder ring 122. First solder ring 112 passes through the solder bonding with second solder ring 122 after, then, under the same solder ring width condition, all be planar scheme for first solder ring 112 and second solder ring 122's faying surface, the unsmooth structure can be made to this scheme, and the benefit lies in: the effective length of the leakage path of the external gas into the vacuum chamber 13a can be increased, so that the gas leakage rate can be reduced, and the reliability and the service life of the MEMS sensor 1 can be improved. Particularly, for the infrared detector, the temperature change of the MEMS structure 110 after receiving the target infrared radiation is very weak, and the vacuum degree in the vacuum chamber 13a is required to be less than E-3Torr in order to avoid the bridge floor heat loss due to air convection as much as possible. Due to the uneven structure of the first welding ring 112 and the second welding ring 122, the packaging leakage rate of the vacuum chamber 13a is reduced, the vacuum degree maintaining time in the vacuum chamber is prolonged, and the reliability of the infrared detector is directly guaranteed.

Secondly, the bonding surfaces of the first bonding ring 112 and the second bonding ring 122 are non-planar uneven structures, which can improve the shear strength of the MEMS sensor 1, thereby improving the reliability against impact.

Third, for the MEMS structure 110 with high requirement for shock resistance, the annular groove 14 and the annular protrusion 15 engage the first welding ring 112 and the second welding ring 122 with smaller thickness, so as to further improve the shear strength of the MEMS sensor 1, thereby improving the shock resistance reliability.

To further increase the length of the gas leakage path, referring to fig. 1, the ratio between the depth D of the annular groove 14 and the width W1 of the annular groove 14 is greater than 1/10; the ratio between the height H of the annular projection 15 and the width W2 of the annular projection 15 is greater than 1/10.

Further, the first and second solder rings 112 and 122 are preferably soldered together by an indium-based solder. In some embodiments, tin-based solder soldering may also be employed. In certain use environments of the MEMS sensor 1, such as high temperatures, the organic flux in the solder paste may volatilize and release gases, causing the pressure within the vacuum cavity 13a to increase. Compared with tin paste solder, indium-based solder or tin-based solder has no organic fluxingTherefore, the agent does not release gas at high temperature and does not affect the degree of vacuum in the vacuum chamber 13 a. The indium-based solder and the tin-based solder are alloys in which indium and tin are main components and other metals such as gold, silver, and copper are doped. The indium-based solder is, for example, In₉₇Ag₃Or In₉₅Ag₅。

The first embodiment of the present invention also provides a method for manufacturing the MEMS sensor shown in fig. 1 to 3. Fig. 4 is a flow chart of a method of fabrication. Fig. 5 to 10 are intermediate schematic diagrams corresponding to the flow in fig. 4.

First, referring to step S1 in fig. 4, fig. 5 and fig. 6, a prefabricated substrate 11' and a prefabricated cover plate 12' are respectively provided, the prefabricated substrate 11' including a MEMS structure 110 and a first bonding pad 111 disposed around the MEMS structure 110; the prefabricated cover plate 12' includes a second welding area 121.

The pre-fabricated substrate 11' may include a first semiconductor substrate on which the MEMS structure 110 is disposed. The MEMS structure 110 may depend on the type of MEMS sensor 1. For example, when the MEMS sensor 1 is an acceleration sensor, a pressure sensor, or an angular velocity sensor, the MEMS structure 110 may include a fixed electrode and a movable electrode. The movable electrode may be a cantilever beam supported at one end, or a cantilever beam supported at both ends. For another example, when the MEMS sensor 1 is an uncooled infrared focal plane detector, the MEMS structure 110 includes a photosensitive structure with an uncovered upper surface. The MEMS structure 110 is not limited in this embodiment, and only needs to be disposed in a vacuum environment.

In the present embodiment, referring to fig. 5, the first bonding region 111 has a first passivation layer 113. The material of the first passivation layer 113 may be silicon nitride. In other embodiments, the first bonding region 111 may have a first dielectric layer or a first semiconductor layer. The material of the first dielectric layer may be silicon dioxide. The material of the first semiconductor layer can be doped polysilicon or a monocrystalline silicon substrate. Or the first land region 111 has a stacked-layer structure including at least two layers of the first dielectric layer, the first passivation layer, and the first semiconductor layer. The present embodiment does not limit the kind of material of the first land 111.

The pre-fabricated cover plate 12' may comprise a second semiconductor substrate.

In the present embodiment, referring to fig. 6, the second bonding pad 121 has a second dielectric layer 123. The material of the second dielectric layer 123 may be silicon dioxide. In other embodiments, the second bonding region 121 may have a second passivation layer or a second semiconductor layer. The material of the second passivation layer may be silicon nitride. The material of the second semiconductor layer can be doped polycrystalline silicon or a monocrystalline silicon substrate. Or, the second bonding pad 121 has a stacked-layer structure including at least two layers of the second dielectric layer, the second passivation layer, and the second semiconductor layer. The present embodiment does not limit the kind of material of the second lands 121.

Next, referring to step S2 in fig. 4, fig. 7 and fig. 8, annular grooves 14 distributed in the circumferential direction are formed in the first land 111; annular projections 15 are formed at the second land 121 so as to be distributed in the circumferential direction.

The annular groove 14 and the annular protrusion 15 may be implemented by dry etching. Specifically, step S2 may include:

step S21, forming photoresist layers on the prefabricated substrate 11 'and the prefabricated cover plate 12', respectively; then, exposing the photoresist layer by adopting a corresponding mask; by development, respective patterned photoresist layers are formed.

Step S22, dry etching the first passivation layer 113 with the corresponding patterned photoresist layer as a mask to form an annular groove 14 in the first passivation layer 113; the second dielectric layer 123 is dry etched using the corresponding patterned photoresist layer as a mask to form the annular protrusion 15 in the second dielectric layer 123.

In step S23, the remaining photoresist layer is removed by ashing.

Next, referring to step S3 in fig. 4, fig. 9 and fig. 10, a first solder ring 112 is formed on the first land 111 so that the prefabricated substrate 11' is formed as the substrate 11, the first solder ring 112 conformally being positioned on the first land 111; a second weld ring 122 is formed at the second weld zone 121 such that the prefabricated cover plate 12' forms the cover plate 12, the second weld ring 122 being conformally located on the second weld zone 121.

The material of the first solder ring 112 and the second solder ring 122 is metal, such as copper or aluminum. The first solder ring 112 may be formed by an electron beam evaporation or sputtering process. The second weld ring 122 may also be formed by an e-beam evaporation or sputtering process.

The electron beam evaporation or sputtering process may form the metal layer on the entire surface, and the metal layer in the region outside the first and

second lands

111 and 121 may be removed by a dry etching process or a wet etching process.

The thickness of the metal layer is thin, and the thickness of the metal layer satisfies, for the substrate 11: the cross section of the annular recessed region surrounded by the surface of the metal layer away from the first land 111 in the vertical circumferential direction coincides with the cross section of the annular groove 14 in the vertical circumferential direction. For the cover plate 12, the thickness of the metal layer satisfies: the cross section of the annular projection region surrounded by the surface of the metal layer remote from the second land 121 in the vertical circumferential direction coincides with the cross section of the annular projection 15 in the vertical circumferential direction.

Before the metal layer is formed by electron beam evaporation or sputtering, the preformed substrate 11 'and the preformed cover plate 12' may be immersed in an organic solvent for ultrasonic oscillation to clean the residue. The organic solvent may be at least one of acetone, ethanol, diethyl ether, and isopropanol.

Thereafter, referring to step S4 in fig. 4 and fig. 1, the first welding ring 112 and the second welding ring 122 are welded together, so that the substrate 11 and the cover plate 12 form the sealing structure 13 to define the MEMS structure 110 in the vacuum cavity 13 a.

This step is preferably performed in a vacuum environment, and in particular, may be performed using a vacuum bonder. In the vacuum bonding machine, the solder reaches the melting point and begins to melt, the solder rapidly spreads on the wetting layers of the first welding ring 112 and the second welding ring 122 and fills the uneven structure, and after the temperature is reduced, the solder solidifies to form a chain-shaped rodent structure extending in the radial direction with the first welding ring 112 and the second welding ring 122.

The first and second solder rings 112 and 122 are preferably soldered together by an indium-based solder. In some embodiments, tin-based solder soldering may also be employed. In contrast to solder paste, indium-based solder and tin-based solder do not release gas at high temperature because they do not contain organic flux, and do not affect the degree of vacuum in the vacuum chamber 13 a.

Fig. 11 is a schematic cross-sectional structure diagram of a partial structure of a MEMS sensor according to a second embodiment of the present invention. Referring to fig. 11, the MEMS sensor 2 of the second embodiment is substantially the same as the MEMS sensor 1 of the first embodiment, and differs therefrom only in that: the annular groove 14 and the annular protrusion 15 comprise two turns.

The number of turns of the annular groove 14 coincides with that of the annular projection 15. In this embodiment, the size of each ring-shaped groove 14 is the same, and the size includes width and depth; the dimensions of each ring of annular protrusions 15 are also the same, including width and height. In other embodiments, the size of the annular grooves 14 may be different, such as different widths and/or depths; the size of the annular projections 15 may also be different, for example different in width and/or height.

In other embodiments, the annular groove 14 and the annular protrusion 15 may also include more than two circles.

The greater the number of the annular grooves 14 and the annular protrusions 15, the more the effective length of the gas leakage path can be increased.

Fig. 12 is a schematic cross-sectional structure diagram of a partial structure of a MEMS sensor according to a third embodiment of the present invention. Referring to fig. 12, the MEMS sensor 3 of the third embodiment is substantially the same as the MEMS sensors 1 and 2 of the first and second embodiments, and differs therefrom only in that: the first weld ring 112 comprises, in order towards the cover plate 12: a first adhesive layer 112a, a first barrier layer 112b, and a first wetting layer 112 c; the second solder ring 122 includes, in order toward the substrate 11: a second adhesive layer 122a, a second barrier layer 122b, and a second wetting layer 122 c.

In this embodiment, the first adhesive layer 112a is made of a metal, such as titanium or chromium, having good adhesion to the first passivation layer 113 and a coefficient of thermal expansion matched thereto. First barrier layer 112b is selected to be a metal, such as nickel, that adheres well to both first wetting layer 112c and first adhesion layer 112a, has a coefficient of thermal expansion between the two layers, and has intermediate solderability. The first wetting layer 112c is also an oxidation preventing layer, and a metal having stable performance, good wettability, difficult oxidation, and good brazing performance is selected, and the metal is, for example, gold. The second adhesion layer 122a is selected to have good adhesion to the second dielectric layer 123 and a coefficient of thermal expansion matched metal, such as titanium or chromium. Second barrier layer 122b is selected to be a metal, such as nickel, that adheres well to both the second wetting layer 122c and the second adhesion layer 122a, has a coefficient of thermal expansion between the two layers, and has intermediate solderability. The second wetting layer 122c is also an oxidation preventing layer, and a metal having stable performance, good wettability, difficult oxidation, and good brazing performance is selected, and the metal is, for example, gold.

In other embodiments, only the first weld ring 112 may sequentially include, in the direction toward the cover plate 12: a first adhesive layer 112a, a first barrier layer 112b, and a first wetting layer 121 c; or only the second solder ring 122 comprises in sequence towards the substrate 11: a second adhesive layer 122a, a second barrier layer 122b, and a second wetting layer 122 c.

Fig. 13 is a schematic cross-sectional structure diagram of a MEMS sensor according to a fourth embodiment of the present invention. Referring to fig. 13, the MEMS sensor 4 of the fourth embodiment is substantially the same as the

MEMS sensors

1, 2, and 3 of the first, second, and third embodiments, and differs therefrom only in that: the first land 111 has annular projections 15 distributed in the circumferential direction, and the second land 121 has annular recesses 14 distributed in the circumferential direction.

Referring to fig. 13, the annular protrusion 15 and the annular groove 14 allow the first weld ring 112 and the second weld ring 122 to be engaged.

Fig. 14 is a schematic cross-sectional structure diagram of a MEMS sensor according to a fifth embodiment of the present invention. Referring to fig. 14, the MEMS sensor 5 of the fifth embodiment is substantially the same as the

MEMS sensors

1, 2, 3, and 4 of the first, second, third, and fourth embodiments, and differs only in that: the first land 111 has annular grooves 14 distributed along the circumferential direction, and the second land 121 is a plane.

The first solder ring 112 is conformally disposed on the first land 111, so that the surface of the first solder ring 112 away from the first land 111 encloses an annular recessed region, and the cross section of the annular recessed region in the vertical circumferential direction is identical to the cross section of the annular groove 14 in the vertical circumferential direction. The second weld ring 122 is conformally located on the second land 121, and thus, a surface of the second weld ring 122 away from the second land 121 is planar.

Referring to fig. 14, the solder layer 16 includes a first surface and a second surface opposite to each other, the first surface having a shape and size matching the shape and size of the first solder ring 112, and the second surface having a shape and size matching the shape and size of the second solder ring 122.

In other embodiments, the first welding area 111 may have annular protrusions 15 distributed along the circumferential direction, and the second welding area 121 may be a plane; or the first land 111 is a plane, and the second land 121 has annular grooves 14 distributed along the circumferential direction; or the first land 111 is a plane, and the second land 121 has annular projections 15 distributed in the circumferential direction.

Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one of ordinary skill in the pertinent art without departing from the scope or spirit of the present invention, and the scope of the present invention is defined by the appended claims.

Claims

1. A MEMS sensor, comprising:

2. The MEMS sensor of claim 1, wherein the first bond pad has a circumferentially distributed annular groove and the second bond pad has a circumferentially distributed annular projection, the annular groove and the annular projection engaging the first bond ring with the second bond ring; or the first welding zone has annular protrusions distributed along the circumferential direction, the second welding zone has annular grooves distributed along the circumferential direction, and the annular protrusions and the annular grooves enable the first welding ring and the second welding ring to be meshed; or the first welding area is provided with annular grooves or annular bulges distributed along the circumferential direction, and the second welding area is a plane; or the first welding area is a plane, and the second welding area is provided with annular grooves or annular bulges distributed along the circumferential direction.

3. The MEMS sensor of claim 1, wherein the annular groove or the annular protrusion comprises more than two turns.

4. The MEMS sensor of claim 3, wherein the size of each ring of the annular groove or each ring of the annular protrusion is the same or different.

5. The MEMS sensor according to claim 1, wherein a cross section of the annular groove or the annular protrusion perpendicular to the circumferential direction is triangular, square, rectangular, regular trapezoid, or inverted trapezoid.

6. The MEMS sensor of claim 1, wherein a ratio between a depth of the annular groove and a width of the annular groove is greater than 1/10; or the ratio between the height of the annular projection and the width of the annular projection is greater than 1/10.

7. The MEMS sensor of claim 1, wherein the first weld ring comprises, in order toward the cover plate: a first adhesive layer, a first barrier layer and a first wetting layer; and/or the second welding ring sequentially comprises towards the substrate direction: a second adhesion layer, a second barrier layer, and a second wetting layer.

8. The MEMS sensor according to claim 1, wherein the first bonding region has at least one of a first dielectric layer, a first passivation layer or a first semiconductor layer, the annular groove is located within the first dielectric layer, the first passivation layer or the first semiconductor layer, or the material of the annular protrusion is the first dielectric layer, the first passivation layer or the first semiconductor layer; or the second welding area is provided with at least one of a second dielectric layer, a second passivation layer or a second semiconductor layer, the annular groove is positioned in the second dielectric layer, the second passivation layer or the second semiconductor layer, or the annular bulge is made of the second dielectric layer, the second passivation layer or the second semiconductor layer.

9. The MEMS sensor of claim 1, wherein the first and second bond rings are bonded together with an indium-based or tin-based solder.