Study of Poly-SiGe Structural Properties for Modularly Integrated MEMS

Polycrystalline silicon-germanium (poly-SiGe) is an attractive structural material for surface micromachining due to its low deposition temperature (<450C), which enables high performance MEMS devices to be fabricated directly on top of CMOS electronics [1]. Achieving low strain gradient within a low-temperature-deposited polySiGe film remains a major challenge for inertial sensors, which utilize large-area suspended structures that are more prone to warpage. In this work, we characterize the strain gradient of low-temperature-deposited poly-SiGe films using out-of-plane curvature measurements of released cantilever beam arrays, stress-vs.-depth profiles, and cross-sectional TEM analyses.