Single-Crystalline Silicon Layer Transfer to a Flexible Substrate Using Wafer Bonding

This paper reports the successful transfer of a thin single-crystalline silicon film to a flexible, transparent polymer substrate. Thin-film silicon on polymer was realized by bonding a silicon-on-insulator (SOI) wafer to a flexible substrate using a spin-on polymer as an adhesive. The SOI wafer was thinned by a grinding operation followed by chemical mechanical polishing (CMP). The SOI was further thinned to the buried oxide using wet etchants. The residual stress in the transferred substrate was investigated by ultraviolet (UV) micro-Raman spectroscopy and numerical modeling. Both approaches showed that a low level of stress was created at the bonded interface during the layer transfer.