Low-pressure MEMS pressure sensor and preparation method thereof

Abstract

The invention discloses a low-pressure MEMS pressure sensor and a preparation method thereof. The sensor comprises a device layer, a first supporting layer and a second supporting layer, wherein the first supporting layer and the second supporting layer are connected to the two opposite sides of the device layer in a bonding mode. A first cavity is etched in the surface of one side, close to the first supporting layer, of the device layer, and a second cavity is etched in the surface of one side, close to the device layer, of the second supporting layer; the device layer between the first cavity and the second cavity is used as a strain film layer; a pressure-sensitive assembly is arranged on the surface of the side, close to the second supporting layer, of the strain film layer, a closed-loop second conductive strip is arranged on the side, close to the second supporting layer, of the device layer and surrounds the periphery of the edge of the Wheatstone bridge component, and the second conductive strip and the Wheatstone bridge component are spaced through a groove. And the power supply end of the Wheatstone bridge part is electrically connected with the second conductive strip. According to the structure, the influence of stress on the strain film is reduced, the etching precision of the first cavity is improved, the chip area is reduced, the cost is reduced, and the uniformity of the thickness of the strain film can be guaranteed.

Description

technical field [0001] Embodiments of the present invention relate to the technical field of sensors, and in particular, to a low-voltage MEMS pressure sensor and a preparation method thereof. Background technique [0002] Pressure sensors are widely used in many industries such as automotive electronics, petrochemicals, aerospace, medical equipment and consumer electronics, accounting for one-third of the entire sensor market. According to different working principles, pressure sensors can be divided into piezoresistive, capacitive, piezoelectric, surface acoustic wave, Hall effect and so on. Among them, piezoresistive pressure sensors based on MEMS technology are widely used due to their high sensitivity and low cost. [0003] However, the existing piezoresistive low-pressure pressure sensors mostly use the back-cavity wet deep silicon etching method, and the etching depth is relatively deep (above 300um). The large chip area to supplement the lateral etching increases t...

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Problems solved by technology

[0003] However, most of the existing piezoresistive low-pressure pressure sensors use back cavity wet deep silicon etching to form a film, and the etching depth is relatively deep (above 300um). Since the wet etching is not vertically etched, it requires more The large chip area supplements the lateral etching, which increases the cost, and the deep etching depth also makes it difficult to control the thickness uniformity and consistency of the strained film; in addition, the existing piezoresistive low-pressure pressure sensor is only on the back Bonding a piece of glass is prone to stress imbalance

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