Transfer of thin epitaxial silicon films by wafer bonding and splitting of double layered porous silicon for SOI fabrication

A double layered porous silicon with different porosity is formed on a heavy doped p-type Si (111) substrate by changing current density during the anodizing. A high quality epitaxial mono-crystalline silicon film is grown on the porous silicon using an ultra-high vacuum electron beam evaporator. This wafer is bonded with other silicon wafer with a thermal oxide layer at room temperature. The bonded pairs are split along the porous silicon layer during subsequent thermal annealing. Thus the epitaxial Si film is transferred to the oxidized wafer to form a silicon-on-insulator structure. SEM, XTEM, spreading resistance probe and Hall measurement show that the SOI structure has good structural and electrical quality.