Patent ID: 6595066
Filing Date: 2003-07-22
Classification: G01L

Abstract:
A leadless semiconductor sensor for measuring differential pressure across a diaphragm of the sensor and operable in the presence of an excessive unidirectional force applied to said diaphragm from either direction to stop said diaphragm from further deflection during the presence of said excessive force which otherwise would tend to fracture said diaphragm, comprising:a semiconductor silicon wafer on which said sensor is fabricated, said wafer including a top surface having an active area surrounded by a p+ rim, said active area including p+ piezoresistors forming a Wheatstone Bridge array, said top surface further having p+ fingers each coupled to a respective one of said piezoresistors, with each p+ finger associated with a metal contact area for enabling an electrical connection to be made to an associated one of said piezoresistors, a first glass cover member having first and second slotted apertures in communication with said active area and having a central depression located between said apertures operative as a stop, said glass cover member bonded to a bottom surface of said wafer to enable a force to be applied to said bottom surface at said active regions through said slotted apertures, a second glass contact member having first and second slotted apertures in communication with said active area to enable a force to be applied to said top surface of said wafer through said slotted apertures of said second glass contact member, the second glass contact member further having a plurality of contact apertures each one congruent with and associated with one of said metal contact areas, said second glass contact member bonded to said top surface of said wafer at said p+ rim, said second glass contact member having a depression located between said slotted apertures to form a stop surface, wherein when an excessive force is applied to said wafer of said sensor through said slotted apertures in either direction, said first and second glass members stop said diaphragm from excessive deflection.