SILICON ON NOTHING (SON) - FABRICATION, MATERIAL AND DEVICES

摘要

The key point of the new SON process lies in the transfer of the lattice continuity from a bulk Silicon substrate via a SiGe layer to the Silicon cap layer, both of these layers being obtained by epitaxy. The thin SiGe layer is next removed from underneath the Si cap in an isotropic plasma-assisted chemical dry-etching that guaranties selectivity factors as large as 100:1. The mono-crystalline Si cap layer resulting from this process lies on an air-gap, which gives the name (Silicon On Nothing) to the process. Depending on application, this air-gap may be refilled with a dielectric or left empty. In both cases, the thickness of the Si cap as well as that of the air-gap (dielectric) may be in the range of a few nanometers with a control of less than 1nm. Such specifications on Si cap and buried dielectric layer thickness are out of reach of any known SOI substrate technology, thus opening access to new applications. In the paper we will present the SON process and a large spectrum of applications ranging from MOS SOI and GAA transistors, to notched gates, DRAM capacitors, 3-D integration, etc.