ABSTRACT
This chapter describes the mainstream of the selective silicon–germanium etching and its applications. It presents the Silicon-on-Nothing (SON) process and its possible technological variants within the process of simplification, and improvement of versatility and robustness. The SON process opens access to extremely thin films at the same time offering the thickness control as fine as the resolution of the epi process. The high-resolution transmission electron microscopy cross-section made on a finished extremely thin 5nm-thick SON transistor demonstrates that the bottom interface is almost as smooth as the upper one. SON architecture allows comfortable silicidation thanks to the metallurgical contact between S/D and the bulk. The remaining Si-cap layer is then supported by the gate stack that bridges the active area in the perpendicular direction, as in the basic SON process. The SON process may also be easily adapted to fabrication of double gate or gate-all-around (GAA) devices.
