A strain-sensor-integrated test bed for electro mechanical characterization of VLSI probe

Abstract

A piezoresistive bridge circuit on a CMOS LSI chip was post-processed by Silicon Deep Reactive Ion Etching (DRIE) to integrate a strain sensor in a freestanding cantilever. The cantilever is used to characterize contact-force to contactresistance relationship of the CMOS-MEMS Probe device for VLSI Circuit testing application. The sensor can be deployed in two scenarios; one is to use it as force sensor of contact pad, and the use as an integrated force sensor of a CMOS-MEMS test probe. A static measurement of a cantilever-type device gave strain gauge characteristic. In addition, a Lorentz force driven MEMS actuator is also proposed to in-situ calibrate the strain sensor. The experimental gauge factors of this sensor were 21 in static device and 25 in dynamic device.