CN-117191228-B - Low-stress structure suitable for monolithic integrated pressure sensor array

CN117191228BCN 117191228 BCN117191228 BCN 117191228BCN-117191228-B

Abstract

The invention relates to a low-stress structure suitable for a monolithic integrated pressure sensor array, which comprises a pressure sensing structural layer, a fixed supporting layer, a longitudinal stress buffer layer and a connecting plate which are sequentially overlapped from top to bottom, wherein the pressure sensing structural layer comprises a group of piezoresistive bridge structural unit arrays arranged on the surface, a back cavity is arranged on the lower side of each piezoresistive bridge structural unit, a first annular groove is arranged on the peripheral side of each piezoresistive bridge structural unit, a first through hole which is correspondingly communicated with each back cavity is arranged on the fixed supporting layer, a boss corresponding to the piezoresistive bridge structural units is arranged on the lower surface of each longitudinal stress buffer layer, a second through hole which is correspondingly communicated with each first through hole is arranged on each boss, the surfaces of the bosses are connected with the connecting plate to form lattice contact connection, and a third through hole which is correspondingly communicated with each second through hole is arranged on the connecting plate. The invention realizes the transverse and longitudinal buffering of external stress, and the structure does not obviously increase the processing difficulty of the MEMS pressure sensor array chip, and the invention can be flexibly applied and is easy to realize.

Inventors

ZHAO JUAN
GUO WEI
SONG YOUYU
LI AO
DING YANLI
GAO YUANYUAN

Assignees

华东光电集成器件研究所

Dates

Publication Date: 20260508
Application Date: 20230830

Claims (5)

1. The low-stress structure suitable for the monolithically integrated pressure sensor array is characterized by comprising a pressure sensing structural layer (100), a fixed supporting layer (200), a longitudinal stress buffer layer (300) and a connecting plate (400) which are sequentially overlapped from top to bottom; The pressure sensing structural layer (100) comprises a group of piezoresistive bridge structural units (101) arranged on the upper surface of the pressure sensing structural layer, a back cavity (102) is arranged on the lower side of each piezoresistive bridge structural unit (101), a first annular groove (103) is arranged on the peripheral side of each piezoresistive bridge structural unit (101), and the groove depth of the first annular groove (103) is larger than the thickness of each piezoresistive bridge structural unit (101); the fixed supporting layer (200) is provided with a first through hole (201) which is correspondingly communicated with each back cavity (102); the longitudinal stress buffer layer (300) comprises bosses (301) which are arranged on the lower surface of the longitudinal stress buffer layer in an array manner and correspond to the piezoresistive bridge structure units (101), each boss (301) is provided with a second through hole (310) which is correspondingly communicated with each first through hole (201), and the surfaces of the bosses (301) are connected with the connecting plates (400) to form lattice contact connection; a third through hole (401) which is correspondingly communicated with each second through hole (310) is arranged on the connecting plate (400); The second through hole (310) at least comprises a folding through hole unit (311) which is coaxially arranged, the folding through hole unit (311) is of a hole type structure with small opening sizes at two ends and large cross section sizes at the middle part, and parameters from the opening sizes at the two ends to the maximum cross section sizes at the middle part are linearly increased; And a plurality of layers of metal wiring (104) are arranged on the pressure sensing structural layer (100), the plurality of layers of metal wiring (104) are electrically connected with the chip bonding area (105), each piezoresistive bridge structural unit (101) is interconnected with the plurality of layers of metal wiring (104) through bonding wires (107), and the chip bonding area (105) is connected with the multi-channel switch gating chip (106).
2. A low stress structure suitable for use in a monolithically integrated pressure sensor array according to claim 1, wherein a second annular groove (302) is further provided at the peripheral side of each of said bosses (301), the groove depth direction of the second annular groove (302) being axially arranged along the second through hole (310).
3. A low stress structure for a monolithically integrated pressure sensor array according to claim 2, wherein the second annular groove (302) has a groove depth exceeding the position of the largest cross-sectional dimension of the lowest folded via unit (311) of the second via (310).
4. A low stress structure suitable for use in a monolithically integrated pressure sensor array according to claim 3, wherein said second through hole (310) has a rectangular cross sectional shape.
5. A low stress structure suitable for use in a monolithically integrated pressure sensor array according to claim 1 or 4, wherein the lower surface of the web (400) is further provided with an air guide nozzle (402) communicating with each third through hole (401).

Description

Low-stress structure suitable for monolithic integrated pressure sensor array Technical Field The invention relates to the technical field of MEMS sensor chip structures, in particular to a low-stress structure suitable for a monolithic integrated pressure sensor array. Background MEMS (micro electro mechanical system) sensors are widely used in consumer electronics, automotive electronics, internet of things, defense industry and numerous industrial products, and with the development of technology, higher and higher requirements are also put on the performance of MEMS sensors. And the influence of external stress on the performance of the MEMS sensor is particularly remarkable. When external stress changes, corresponding strain is caused, and the strain is transmitted to the sensitive structure, so that the output signal of the sensor changes, especially the MEMS sensor based on the capacitive, piezoresistive and resonant detection principles. The MEMS pressure sensor based on silicon piezoresistance has the advantages of high sensitivity, no hysteresis, high frequency response, high output level and convenient use, and has the defect of being sensitive to external stress. The pressure sensing assembly applied to the pressure scanning valve of the intelligent MEMS pressure module product at present, for example, a pressure scanning valve with the publication number of CN114777992A, adopts a plurality of independent pressure sensor packaging chips to integrate on a drive control circuit board, has the advantages that no crosstalk exists between each independent pressure sensor chip, can realize better stress isolation, has the defects of large volume, and each independent pressure sensor chip has no longitudinal buffer to external stress and is easy to be interfered by the external stress. For MEMS pressure sensor array chips, although the volume of pressure module products can be effectively reduced, the structure is easy to be interfered by external stress, and the service performance of the products is affected. Disclosure of Invention In order to solve the problem that a pressure sensor array chip in the prior art is easily interfered by external stress, the invention provides a low-stress structure suitable for a monolithic integrated pressure sensor array. The technical scheme is as follows: a low stress structure suitable for monolithic integrated pressure sensor array comprises a pressure sensing structure layer, a fixed supporting layer, a longitudinal stress buffer layer and a connecting plate which are sequentially overlapped from top to bottom; The pressure sensing structure layer comprises a group of piezoresistive bridge structure unit arrays arranged on the upper surface of the pressure sensing structure layer, a back cavity is arranged on the lower side of each piezoresistive bridge structure unit, a first annular groove is arranged on the peripheral side of each piezoresistive bridge structure unit, and the depth of the first annular groove is larger than the thickness of each piezoresistive bridge structure unit; the fixed supporting layer is provided with a first through hole which is correspondingly communicated with each back cavity; the longitudinal stress buffer layer comprises bosses which are arranged on the lower surface of the longitudinal stress buffer layer in an array manner and correspond to the piezoresistive bridge structure units, each boss is provided with a second through hole which is correspondingly communicated with each first through hole, and the surfaces of the bosses are connected with the connecting plate to form lattice contact connection; and a third through hole which is correspondingly communicated with each second through hole is formed in the connecting plate. Further, the second through hole at least comprises a folding through hole unit which is coaxially arranged, the folding through hole unit is of a hole type structure with small opening sizes at two ends and large cross section sizes in the middle, and parameters from the opening sizes at two ends to the maximum cross section sizes in the middle are linearly increased. Further, a second annular groove is further formed in the periphery of each boss, and the groove depth direction of the second annular groove is axially arranged along the second through hole. Further, the groove depth of the second annular groove exceeds the position where the maximum cross-sectional dimension of the lowest folded through hole unit in the second through hole is located. Further, the cross section of the second through hole is rectangular. Further, the lower surface of the connecting plate is also provided with an air guide needle mouth communicated with each third through hole. Further, a plurality of layers of metal wiring are arranged on the pressure sensing structural layer, the plurality of layers of metal wiring are electrically connected with the chip bonding area, each piezoresistive bridge structural unit is int