Hybrid Integration of Ultrathin-Body Partially Insulated MOSFETs and a Bulk MOSFET for Better IC Performance: A Multiple- $V_{\rm TH}$ Technology Using Partial SOI Structure

The hybrid integration of ultrathin-body partially insulated MOSFETs (UTB PiFETs) and a bulk MOSFET was investigated. With a partial silicon-on-insulator (SOI) process using a SiGe sacrificial layer, UTB PiFETs with thin buried insulation layers were realized on the same bulk Si wafer with a bulk MOSFET. A partially insulating oxide (PiOX)-under-channel PiFET is suitable from the viewpoint of high-speed operation due to its SOI-like characteristics. On the other hand, a PUSD PiFET is useful from the viewpoint of low stand-by power operation due to its low junction leakage current. Through hybrid integration, not only multiple V_TH´s can be obtained but also the technical difficulties of bulk MOSFETs can be alleviated. Thus, hybrid integration is a very useful process technique to implement integrated-circuit products with optimized power and performance management.