Direct integration of field effect transistors as electro mechanical transducer for stress

Abstract

The detection of motion with an active electrical device like a transistor allows to shrink the transducer to a few micrometers and to integrate it into a CMOS-process. A promising method for that is using the piezoresistive effect in the channel of a transistor. We have investigated the fundamental behavior of strain sensitive transistors with respect to different transistor parameters. Therefore the transistors have been simulated by using a modified BSIM3.3 model. The simulations showed an increase of the drain current between 3.5 % and 5.8 % for a 60 MPa stress and an acceptable shift of threshold voltage and almost no increase of leakage current. For metrological characterization pressure sensitive silicon membranes have been fabricated as strain inducing elements. First measurements with elongated membranes confirmed the simulation results.