Linearity of Piezoresistive Nano-gauges for MEMS Sensors☆

Abstract The work discusses the mechanical properties and the response linearity of sub-micrometric crystalline Silicon beams used as piezoresistive sensing elements (nano-gauges) in MEMS sensors. The study is based on a suitably developed test structure that allows applying bidirectional stresses to a gauge with a cross-section of (250 nm)2, and to monitor the displacement both through a reference linear capacitive sensor and through the nano-gauge piezoresistive variation. Experimental measurements estimate a nominal strength of 6.6 GPa, and a linear range of 2.3 GPa and 1.1 GPa under tensile and compressive stresses respectively, the latter value being limited by buckling effects.