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Relative and absolute pressure sensor combined on chip

  • US 10,031,003 B2
  • Filed: 12/02/2015
  • Issued: 07/24/2018
  • Est. Priority Date: 12/02/2014
  • Status: Active Grant
First Claim
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1. A method for manufacturing a pressure measurement system in a wafer for measuring an absolute pressure and a relative pressure, the method comprising:

  • a first step wherein a shallow cavity and a deep cavity are etched in a base wafer, such that the depth of the shallow cavity is smaller than the depth of the deep cavity;

    a second step wherein a top wafer is applied to the base wafer;

    a third step wherein the top wafer is thinned for forming a first membrane over the shallow cavity and for forming a second membrane over the deep cavity, and wherein elements are formed in the top wafer, the elements allowing performing pressure measurements resulting in a first sensor and a second sensor, respectively; and

    a fourth step wherein back thinning is applied on the base wafer such that the deep cavity is opened from the backside of the base wafer and that the shallow cavity is still closed by the backside of the base wafer;

    wherein the system can be used for measuring the absolute pressure using the first sensor and the relative pressure using the second sensor, and wherein the etching of the first step defines the edges of the first membrane and of the second membrane in respectively the sensors formed from the shallow cavity and the deep cavity.

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