Fabrication of an ultra-thin silicon wafer with honeycomb structure by Thermal-Stress Induced Pattern Transfer (TIPT) method

A novel process of making ultra-thin silicon wafer by Thermal-stress Induced Pattern Transfer (TIPT) method was reported. The method employs three steps, first a silicon thin film was deposited on a sapphire substrate by plasma enhanced chemical vapor deposition. Second, metal paste was printed on the silicon layer, and finally a thermal annealing process was carried out. After cooling down, the silicon layer together with the metal paste will peeled off from the sapphire substrate because of the differences of thermal expansion coefficient between sapphire substrate and silicon film. An ultra-thin silicon layer of 3 μm thickness was obtained in this study. Furthermore, the silicon layer with the micro-scale and nano-scale honeycomb structure could be obtained by the well-designed of sapphire patterns. An ultra-thin silicon layer with honeycomb structure with 780 nm in diameter and 337 nm in depth was obtained by the TIPT process.