Formation of buried insulating island-like SiO2 layer in silicon

The main goal of this work is the development of a method for the formation of buried insulating SiO2 layer in silicon, based on the effect of oxygen gettering onto the radiation defects created by hydrogen preimplantation. With this aim in mind radiation defects in 20 Ω cm p-type Cz silicon at a depth of 0.8–1 μm were created by 100 keV hydrogen ions implantation. Then, oxygen was introduced from an external plasma source. Its diffusion and gettering into the buried damage layer was performed at temperatures no more than 300 °C. Finally, a vacuum annealing during 2 h at 700 °C was done. The investigation of oxygen in-depth distribution was done by second ion-mass spectroscopy (SIMS) and Rutherford backscattering (RBS) methods. Visualization of the buried electrically active defects formed at a depth corresponding to projective range of the implanted hydrogen was performed by scanning electron microscopy (SEM) in the Surface-Electron-Beam-Induced-Voltage (SEBIV) mode. Estimation of the electrical properties was realized by measurement of the transversal conductance. The obtained experimental data point to formation of buried island-like SiO2 layer under wafer surface (i.e. Si/SiO2 + Si/Si structure) offering dielectric properties.