CMOS stress sensors on [100] silicon

CMOS analog stress sensor circuits based upon the piezoresistive behavior of MOSFET's are presented. On the [100] surface, these circuits provide temperature-compensated outputs that are proportional to the in-plane normal stress difference (/spl sigma/(11)'-/spl sigma//sub 22/') and the in-plane shear stress /spl sigma//sub 22/'. The circuits provide high sensitivity to stress, well-localized stress-state measurement, and direct voltage or current outputs that eliminate the need for tedious /spl Delta/R/R measurements required with more traditional resistor rosettes. The theoretical and experimental results also provide design guidance for calculating and minimizing the sensitivity of traditional analog circuits to packaging-induced die stress.