A method for forming a semiconductor-on-insulator (SOI) substrate is described incorporating the steps of heating a substrate, implanting oxygen into a heated substrate, cooling the substrate, implanting into a cooled substrate and annealing. The steps of implanting may be at several energies to provide a plurality of depths and corresponding buried damaged regions. Prior to implanting, the step of cleaning the substrate surface and/or forming a patterned mask thereon may be performed. The invention overcomes the problem of raising the quality of buried oxide and its properties such as surface roughness, uniform thickness and breakdown voltage Vbd.