Piezoresistive sensor of short- and long- channel MOSFETs on (100) silicon

This study evaluated metal oxide semiconductor field-effect transistor (MOSFETs) with channel lengths/widths of 0.135/10, 0.45/10, and 10/10 ¿m for both the n- and p- channel types used as sensing elements. The results show that the devices with channel lengths/widths of 0.45/10 and 10/10 ¿m have flat saturation current. It suggests that there is a requirement for a device to have a channel length of over 0.45 ¿m to provide better sensing characterization to normalized current change. The experimental result also demonstrates the fine linear dependence of stress distribution to the distance of tested devices from the clamping end for a silicon cantilever. The stress distribution is detected via normalized current change for all the three sizes of channel length and for both the n and p- types. Moreover, the device with larger channel length has better stress sensitivity than that with the smaller one, when the channel width is fixed at 10 ¿m.