High-Efficiency and Low-Temperature Direct Bonding of SiC to Si via Atmospheric Inductively Coupled Plasma Activation

SiC/Si heterostructure exhibits significant potential for applications in advanced electronics and optoelectronic devices, owing to its exceptional thermal and electrical properties. A direct bonding method utilizing plasma to activate surface in a vacuum environment has been developed for SiC/Si heterogeneous integration. The necessity of a vacuum environment reduces the efficiency of plasma-activated bonding (PAB), thus limiting its application in heterogeneous integration. In this study, we investigated the high-efficiency and low-temperature direct bonding of SiC/Si via atmospheric inductively coupled plasma (ICP). The mechanism of ICP activation and direct bonding of SiC/Si pairs was investigated. After less than 5 s of high-energy Ar ICP irradiation, the intrinsic bonds of surface were disrupted, leading to surface activation. The activated surface readily adsorbed hydroxyl groups from a humid environment, resulting in a superhydrophilic (contact angle <3°) surface. This facilitated a dehydration condensation reaction at low temperature (≤250 °C), enabling direct bonding. The original surface conditions were maintained during the activation process and met the requirements for direct bonding. Additionally, ICP irradiation effectively eliminated surface contaminants and enhanced the quality of direct bonding. Using optimized process parameters, the bonding efficiency is more than 99% and the maximum bonding strength is more than 6 MPa. The results of transmission electron microscopy (TEM) demonstrated that the bonding interface was dense and low-defect. Thus, ICP irradiation can efficiently activate the surface and improve the bonding quality without a vacuum environment. The direct bonding of SiC/Si heterostructures through ICP irradiation holds significant potential for the fabrication of high-performance power electronics and micro/nanofluidic devices.