| 摘要 |
PURPOSE:To diffuse B to an optional medium or low concentration, by laminating a thin SiN film, a BN film and a thin SiN film by the CVD method over an Si substrate having an SiO2 film provided with an opening, and by effecting heat treatment. CONSTITUTION:An opening is made through an SiO2 film 2 on an Si substrate 1. The substrate is put in a reaction tube. The substrate and the film are treated with SiH4-NH3-N2 gas at about 850 deg.C to produce a thin SiN film 51. Subsequently, the gas is replaced with B2H6-NH3-N2 gas and the substrate and the film are treated at about 350 deg.C to make a BN film 4. The gas is replaced with SiH4-NH3-N2 gas again and the substrate and the films are treated at about 850 deg.C to laminate an SiN film 5. They are then treated with N2 gas at 1,200 deg.C to produce a B-diffused layer 6. According to this method, the SiN film grows with the lapse of treatment time to hinder B from being supplied from the BN film. Therefore, the B-diffused layer can be set at a desired surface concentration by controlling the thickness of the thin SiN film 51. |
