Nucleation control of silicon on silicon oxide for low-temperature CVD and silicon selective epitaxy

Nucleation processes of Si on Si oxide in a SiH₄-H₂ gas mixture have been investigated by ultraclean, low-pressure chemical vapor deposition (LPCVD) processing, to obtain high selectivity between Si and Si oxide. It was found that the incubation period for Si deposition and the nucleation rate depend not only on the deposition temperature and the SiH₄ partial pressure, but also on the Si oxide materials, and it was proposed that the nucleation proceeds at point imperfections composed of Si bonds on the Si oxide surface. Furthermore, perfectly selective Si epitaxy without the addition of HCl gas has been realized for the first time in via-holes opened in CVD boro-phospho-silicate glass on Si(100) substrate at temperatures as low as 850°C.