Hybrid Pixels With Si Photodiode and 4H-SiC MOSFETs Using Direct Heterogeneous Bonding Toward Radiation Hardened CMOS Image Sensors

For radiation hardened image sensors, a Silicon-On-Insulator (SOI) -Si/ 4H-SiC hybrid pixel device was developed. The hybrid pixel device consists of one Si photodiode and three 4H-SiC nMOSFETs. At fabrication, SOI substrate was directly bonded on 4H-SiC substrate via SiO2. After bonding, the base silicon substrate and Buried Oxide (BOX) were removed by TMAH wet-etching. By using this SOI-Si/ 4H-SiC substrate, the SOI-Si photodiodes and 4H-SiC nMOSFETs were integrated in the same substrate. As a result, a response of the SOI-Si/ 4H-SiC hybrid pixel device to light illumination was successfully demonstrated.