The present invention discloses a method for preparing a
gain-adjustable MEMS pressure
chip, which relates to the technical field of MEMS
chip preparation. The method includes: forming an N+ buried layer area on the surface of a top
silicon layer; bonding the top
silicon layer to a double-polished
silicon wafer, removing the SOI silicon
wafer substrate layer and the
buried oxide layer; forming a
gain circuit area, an isolation area and a piezoresistive area on the top silicon layer;
processing the double-polished silicon
wafer layer to form a back cavity to obtain a MEMS
chip; the collector area of the
gain circuit area is connected to the N+ buried layer area to reduce the series resistance and reduce the influence of parasitic transistors. The gain circuit area of the present invention is located between the inner layer and the outer layer of the isolation area, the piezoresistive area is located within the range of the inner layer, and the gain circuit is integrated in the MEMS chip, which not only shortens the
signal transmission path, but also effectively reduces the
parasitic capacitance and
signal loss in the traditional discrete design. The obtained MEMS pressure chip has the advantages of high integration, high
signal sensitivity, high structural strength, and easy sensor integration.