APPLICATIONS OF BONDING SOI TECHNOLOGY TO HIGH PERFORMANCE LSI CIRCUITS

摘要

Bonding SOI (Silicon-On-Insulator) technology in the application to LSI circuits is reviewed and its future perspectives are discussed. In the past, wafer bonding was used as a niche technology to fabricate special structures, such as DRAM cells with 3D-structure or RF circuit with low-loss substrate. Nowadays, bonding SOI is used in the mainstream CMOS technology and is pushing the limit of LSI performance. In particular, applications of bonding SOI technology, Smart Cut™, are extending from MPUs, low-power ASICs, RF/analog and to DRAM cells, boosting the consumption of SOI wafers. A variety of engineered SOI substrates, such as rotated crystal orientation, hybrid use of crystal orientations, ultrathin BOX, have been developed for obtaining higher performance and novel functions. It is shown that partially-bulk Si (partially-SOI) structure provides a practical solution for SoC applications, where various kinds of circuits with a wide range of requirements are included. On the other hand, strained-SOI substrate fabricated using Smart Cut technology provides a unique solution for bi-axial tensile strain structure. Future MOSFETs, such as ultrathin-film MOSFET, double-gate structures, FinFET, Ge-on-insulator, all of which use bonding technology, have advantages and issues to be solved. Smart Cut™ technology is also extendable to bonding with quartz or compound semiconductors, demonstrating its versatility and further possibilities.