A new processing technique for fabrication of ultra-thin wafer

Abstract

Ultra-thin wafer with high quality was obtained by a new processing technique, which combined ultrasonic wet etching, temporary bonding, and chemical and mechanical polishing (CMP). In order to obtain a warp-free thin wafer, the pristine silicon wafer was subjected to initial thinning by ultrasonic wet etching. The temporary bonding was then conducted to anchor the wafer and ensure a stress-free de-bonding of the polished ultra-thin wafer from the supporting wafer. The subsequent CMP was applied to further reduce the thickness and roughness of the wafer. Measurements showed the as-fabricated ultra-thin wafer had an average thickness of 76 ± 2 μm, an average surface roughness of 0.32 nm, and a compressive stress of 101.4 MPa. The as-fabricated ultra-thin wafer showed improved overall appearance, with no obvious breakage, deformation, or damages on the surface.