| 摘要 |
PURPOSE:To take out optical carriers produced in an Si substrate out of the Si substrate efficiently by a method wherein an SiO2 film is formed on an Si substrate surface by thermal oxidation and, further, an SiO2 film is formed on the first SiO2 film by a CVD method under a normal pressure or a reduced pressure. CONSTITUTION:After the surface of an Si substrate 1 is washed, the substrate 1 is subjected to the thermal oxidation treatment and, as a result, a thermal oxidation SiO2 film 2 is formed on the surface of the Si substrate 1. The exemplary conditions of the thermal oxidation are, as follows: the thermal oxidation temperature is 800-1000 deg.C, the thermal oxidation time is 1-4 hours, the HCl flow rate is 600cc/min. and the O2 flow rate is 30l/min. Then an SiO2 film 3 is further formed on the Si substrate 1 on which the thermal oxidation SiO2 film 2 is formed by an atmospheric pressure CVD method or a low pressure CVD method. Thus the life time of the optical carriers can be improved and the surface recombination rate of the optical carries can be reduced. |
