High temperature pressure sensor and process method thereof

Abstract

The invention discloses a high temperature pressure sensor and a process method thereof, the pressure sensor comprises a silicon-sensitive diaphragm, a pedestal and a TO tube case, wherein a SOI monocrystalline silicon wafer is used as a substrate of the silicon-sensitive diaphragm. A wheatstone bridge is formed by resistance processing and leading wire interconnection in a device layer, and a diaphragm structure which is sensitive to pressure is formed by conducting anisotropy corrosion at a substrate layer. Anodic bonding or silicon-silicon direct bonding or silicon-silicon medium bonding is conducted by the pedestal and the silicon-sensitive diaphragm, wherein the glass sheet or the monocrystalline silicon wafer is used as a substrate of the pedestal. Chip scale package is achieved by using the TO metal tube case for a shell. The high temperature pressure sensor and the process method thereof use a buried oxide layer of the SOI monocrystalline silicon wafer and an illuvial silicon dioxide/silicon nitride passivation layer to wrap and isolate a silicon resistor, and leakage current at high temperature is eliminated. A high temperature ohmic contact electrode structure of multiple layers of silicon dioxide/titanium/ silicon dioxide/ platinum/gold is grown in a spurting mode. Through high temperature resistance bonding and TO packaging technology, the working stability at high temperature is improved. The problem that long term working is difficult to conduct in a high temperature environment by a traditional silicon substrate sensor is solved.

Description

technical field [0001] The invention relates to the field of microelectronic machining, in particular to a high-temperature pressure sensor and a processing method thereof. Background technique [0002] High-temperature resistant sensors manufactured based on microelectronic machining technology are widely used in high-temperature extreme environments such as aerospace and industrial production. One reason why traditional pressure sensors are difficult to work in high temperature environments is that traditional piezoresistive pressure sensors use monocrystalline silicon as a substrate, and P-type diffused resistors are made on N-type silicon substrates, relying on reverse-biased PN junction isolation , when the ambient temperature exceeds 120 ° C, the leakage current of the PN junction will increase, and the isolation will fail; another important factor restricting the maximum operating temperature of the pressure sensor is that the resistivity of the traditional electrode ...

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to provide a high-temperature pressure sensor and its processing method to sol

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