Thermal-mechanical perspectives on hydrophilic- and surface-activated-bonding Si/SiC interfaces for SOI's thermal management enhancement

Integrating high thermal conductivity cost-effective SiC to the Si-active-layer film is an effective solution to enhance the thermal performance of silicon-on-insulator (SOI) and maintain its distinct electrical performance. Although direct bonding of Si films to SiC substrates demonstrates many advantages over epitaxial growth, different bonding techniques may yield disparate bonding qualities and heat dissipation abilities. Here, a comparative analysis from thermal-mechanical-structural perspectives of different Si/SiC interfaces, prepared by hydrophilic bonding (HB) and surface-activated bonding (SAB) methods, is systematically conducted. It was found that the amorphous interlayer thickness and thermal boundary resistance (TBR) of the SAB-Si/SiC heterojunction can be significantly modulated by annealing, accompanied by a beneficial decreased TBR at high working temperatures. Moreover, the residual stress within the Si film by SAB is greatly reduced to an order of magnitude lower than that by HB. In general, the SAB-Si/SiC interface exhibits a tunable microstructure, comparably low TBR, and nearly fully relaxed stress, potentially outperforming the HB-Si/SiC interface when considering the comprehensive performance. This work puts forward an important thermal-mechanical perspective to evaluate interface bonding quality for practical applications, and removes a headache barrier toward wafer-scale high-yield integration of Si active layers onto SiC substrates to greatly enhance SOI devices' thermal management.