Laser Induced Formation of Buried Void Layer in Silicon

Buried void layer formation in silicon substrates was achieved by hydrogen ion implantation followed by 940-nm infrared laser rapid heating. P-type silicon substrates coated with 100-nm-thick thermally grown SiO2 layers were implanted with hydrogen atoms at 5x10 15 and 3x10 16 cm -2 at 60 keV. Structural investigation with analysis of optical reflectivity spectra revealed that 3x10 16 cm -2 implantation caused a void layer with a void ratio of 0.04 at a depth of 250 nm close to the position of hydrogen peak concentration. Laser irradiation at 4.2x10 4 W/cm 2 increased the void ratio to 0.12. No void layer was observed at ion implantation stage for sample with 5x10 15 cm -2 -hydrogen atoms. Laser irradiation at 4.9x10 4 W/cm 2 formed a void layer with a void ratio of 0.013 at a depth of 255 nm.