(1) A pressure sensor is supposed to have a square membrane with a dimension of 500μm and thickness of 25µm. For stabili

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(1) A pressure sensor is supposed to have a square membrane with a dimension of 500μm and thickness of 25µm. For stability and assembly reasons, the thick rim around the membrane must amount to 100μm wide. Two approaches of manufacturing the pressure sensor using (100) silicon wafers of 150mm diameter were considered: (i) Wet chemical deep etching of one wafer and bond to a supporting 150mm wafer (ii) two-wafer process through bond-and-etchback. The thickness of the 150mm silicon wafer is 675µm. If you want to produce the maximum number of pressure sensors per wafer, which process would you use? (You need to determine the final size of the pressure sensor produced for each method of manufacturing). (ii) A pressure sensor uses four piezoresistors to monitor the stress on the Si diaphragm under pressure. These peizoresistors are to be arranged in a Wheatstone bridge configuration. With the information on the and coefficients given in the lecture notes, where would you locate the piezoresistors? Give reasons why. What is the fractional change of resistance as function of the longitudinal stress?