Medium doped non-suspended silicon nanowire piezoresistor using SIMOX substrate

Abstract

Abstract-This paper reports on the enhanced piezoresistive effect in p-type <110> silicon nanowires, fabricated using a top down approach. The silicon nanowire width is varied from 100 to 500nm with thickness of 200 nm and length of 9µm. It is found that the piezoresistive effect increases when the nanowire width is reduced below 350 nm. Compared with micrometre sized piezoresistors, silicon nanowires have produced up to 50% enhancement. Silicon nanowire with cross-section of (100 × 200 nm) with doping concentration of 3.2 × 10 18 cm -3 has produced a gauge factor of 150. The extracted gauge factors are compared with other silicon nanowire experimental publications. The enhancement in piezoresistive effect by employing non-suspended silicon nanowire is beneficial for new MEMS pressure sensors with medium doping concentrations.

Axial asymmetry for improved sensitivity in MEMS piezoresistors

“…Among the three piezoresistive coefficients, π 44 has the greatest effect on resistance change. Values for π 11 and π 12 of undoped silicon in the 〈1 1 0〉 direction are taken from the literature [15] while the value for π 44 is extracted experimentally (as described in section 5 below). An external force is used to bend the cantilever beam.…”