Robust Polycrystalline 3C-Sic-on-Si Heterostructures with Low CTE Mismatch up to 900 °C for MEMS

Abstract

In this paper we present for the first time polycrystalline cubic silicon carbide on monocrystalline silicon (3C-SiC-on-Si) heterostructures with very low coefficient of thermal expansion (CTE) mismatch at temperatures up to 900 °C. The use of different gas flow rates with alternating supply deposition (ASD) in a low-pressure chemical vapor deposition (LPCVD) system allows to tailor the CTE of the 3C-SiC thin films, resulting in thermal stress levels as low as 175 MPa at 900 °C (~300 MPa intrinsic stress at room temperature). This achievement unlocks robust 3C-SiC/Si interfaces for high temperature micro electromechanical systems (MEMS) applications by overcoming the well-known CTE mismatch of ~9 % between Si and 3C-SiC.