Nucleation site control in self-assembling Si quantum dots on ultrathin SiO2/c-Si

We have investigated the nucleation and growth of silicon dots on ultrathin SiO2 layers in low pressure chemical vapor deposition (LPCVD) of a monosilane gas and developed a fabrication technique for positioning the Si dots in conjunction with nanometer-scale modification Of SiO2 surfaces using a scanning tunneling microscope (STM) prior to LPCVD. We found that reactive sites for the Si dot growth are effectively created on the SiO2 surface by electron beam irradiation from a Pt-Lr STM tip in H-2 ambient with a pressure of 1.3 X 10(-5) Pa without causing dielectric degradation. This can be interpreted in terms that the field-emission of not only electrons but also adsorbed atomic hydrogen from the tip apex to the SiO2 surface results in the formation of surface Si-H and/or Si-OH bonds which act as nucleation sites during LPCVD.