US Patent 7540198 Semiconductor device

It is an object of the present invention to provide a small, yet high sensitivity semiconductor device. A semiconductor pressure sensor 1 includes an SOI substrate 2 on which a diaphragm 3 is formed and four piezo resistor elements R1 to R4 provided on the SOI substrate 2. Of the piezo resistor elements R1 to R4, two mutually facing piezo resistor elements R1 to R4 are arranged across the inside and outside of the diaphragm 3 so as to satisfy a relationship of 0.5<Leff/L<1, where L is the overall length and Leff is the length from the inside to edge of the diaphragm 3.