Process for Nanoscale Thick SOI Substrate with Thermally Conductive Buried Insulator
A.Y. Usenko, W.N. Carr and B. Chen
Silicon Wafer Technologies, US
Keywords: silicon-on-insulator, nonstoichiometric silicon nitride
The process for manufacturing of silicon-on-insulator wafers having an ultrathin top single crystalline silicon layer and thermally conductive buried insulator layer is described. This is a layer transfer type process. The process consists of the following steps: (1) implantation of noble gas ions into a donor wafer. A layer of nanobubbles is formed in silicon. The nanobubble layer will further serve to trap hydrogen. A projection range of the implanted ions defines a thickness of silicon layer to be transferred in a nanoscale range. (2) processing of the implanted wafer in hydrogen plasma. Hydrogen diffuses into silicon and form hydrogen platelets. The nanobubbles serve as nuclei for the platelets. (3) deposition of SiN:H layer on a surface of the donor wafer. The nitride is deposited by PECVD at low temperature to exclude outdiffusion of hydrogen from the platelets. The SiN:H is an additional source of hydrogen for building the platelet layer, and also a diffusion barrier to prevent premature hydrogen losses from the platelet layer. (4) polishing of a surface of the deposited nitride to make the surface bondable. (5) bonding of the donor wafer to a handle wafer. The surfaces are activated for bonding due to hydramine groups N-H adsorbed on the mating surfaces. (6) cleavage of the donor wafer along the hydrogen rich layer, postbonding, and SOI wafer finishing. The final SOI wafer has a very thin top silicon layer, and thermally conductive buried insulator layer. An interface between silicon and buried insulator has low interface state density. The final SOI is a promising initial substrate for future generations of chips.
Nanotech 2004 Conference Technical Program Abstract