Direct Wafer Bonding of SiC-SiC by SAB for Monolithic Integration of SiC MEMS and Electronics

Abstract

Although the monolithic integration of silicon carbide (SiC) Micro-Electro-Mechanical Systems (MEMS) and SiC electronics is very promising, it is still very challenging due to the absence of suitable bulk machining technology of SiC. In this research, wafer bonding was proposed to assist the monolithic integration of SiC MEMS and SiC electronics by the formation of a suspended epitaxial SiC membrane. However, currently, SiC-SiC wafer bonding is still very difficult, especially for its direct wafer bonding. Surface activated bonding (SAB) method was applied to realize the direct wafer bonding of SiC-SiC at room temperature. The bonding energy of ∼1.4 J/m² was obtained without orientation dependence. Correspondingly, the tensile strength of bonding interface is ∼12.2 MPa and could be improved by rapid thermal annealing to the values higher than 21.6 MPa. The bonding mechanisms were investigated through Monte Carlo simulation, interface analysis by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX), and in-situ analysis on the activated SiC surfaces by X-ray photoelectron spectroscopy (XPS).