Micro-pressure sensor chip and preparation method thereof

Abstract

The invention discloses a micro-pressure sensor chip and a preparation method thereof. The sensor chip mainly comprises a stress film, a substrate, a piezoresistive strip, a metal lead, an overload protection assembly and the like. According to the specific structure, a stress film with a stress adjusting groove and a stress concentration groove is manufactured on a chip structure substrate. Fourstress concentration grooves are evenly distributed in the edge of the stress film, the four piezoresistor strips are arranged between the ends of every two adjacent stress concentration grooves, andthe piezoresistor strips are connected into a semi-open-loop Wheatstone bridge through the metal leads. The gap between the cross support beam and the bump of the chip back cavity further improves thestress concentration effect at the piezoresistor strip. The main preparation process comprises the following steps of: manufacturing a piezoresistor strip for a cleaned SOI silicon wafer, manufacturing an ohmic contact region by adopting P-type heavy doping, manufacturing a metal lead and a bonding pad, etching a stress concentration groove and a stress adjustment groove by a dry method, manufacturing a back cavity structure of a chip, and finally bonding a manufactured chip structure substrate with anti-overload glass.

Description

technical field [0001] The invention belongs to the technical field of MEMS piezoresistive micro-pressure sensors, and in particular relates to a micro-pressure sensor chip and a preparation method thereof. Background technique [0002] At present, MEMS micro-pressure sensors have been widely used in biomedical, aerospace, wind tunnel testing and other fields, especially in the aerospace field that has strict requirements on the volume, weight, sensitivity and natural frequency of the sensor. MEMS sensors are widely used due to their small size and high precision. For example, in the field of medical equipment, cardiovascular automatic testers use micro-pressure sensors as measurement sensitive elements to measure radial artery information. In order to ensure the accuracy of diagnosis, the accuracy of micro-pressure sensors Higher requirements are placed on performance and repeatability. In the field of unmanned aerial vehicles, it is of great significance to monitor the fl...

AI Technical Summary

Problems solved by technology

[0003] Pressure sensors with different sensitivity principles have their own advantages and disadvantages: for example, piezoelectric sensors are limited by their sensitivity principles and cannot measure static pressure, and the output charge signal needs to be processed by subsequent complex auxiliary circuits; capacitive pressure sensors have high sensitivity, The temperature drift is small, the power consumption is low, but the input impedance is large, it is easily affected by the parasitic capacitance, and it is more sensitive to the interference of the surrounding environment; the resonant pressure sensor has better sensitivity and lower temperature drift, but the process is complex, Low yield rate is its shortcoming; although the piezoresistive pressure sensor is greatly affected by temperature, it has a wide measurement range, can measure static and dynamic signals, has high precision, good dynamic response, and simple post-processing circuit

As the thickness of the stress film structure decreases, the sensitivity of the sensor to pressure will increase, but the nonlinearity of the sensor will also increase, thus increasing the difficulty of signal processing

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