| 摘要 |
PURPOSE:To obtain a P type base layer having poor impurity variation by forming an insulating film having an opening on an N type semiconductor layer wherein a diffusion source including B stipulating the thickness is formed on the whole surface and B is diffused by heat treatment. CONSTITUTION:An oxide film 14 having a diffusion opening 15 is formed on the layer 12 side of a semiconductor layer 11 composing of an N<+> type layer 13 and an N<-> type layer 12 to make a film 16 by hardening the film 14 after applying a liquid diffusion source including B on the film 14 as thick as 2,800-3,500Angstrom . Next, heat treatment is applied at 900-1,200 deg.C under a mixed atmosphere of N2 and O2 having an O2 mixing rate of 10% or less and a P type later 17 is made by keeping the film 16 thickness of 1,500Angstrom or more. After the above procedure, an SiB layer 16' is left with the thickness of 40Angstrom or more on the layer 17 by using a diluted HF solution and the film 16 is removed. Then, the film 14 is renewed to a film 14' to apply heat treatment and the layer 17 is changed to a deep P type base layer 17' by diffusing B in the layer 16'. Next, a P<+> type base contact layer 18' is provided around the layer 17', an N<+> type base contact layer 18' in the layer 17' and an N<+> type emitter layer 19 in the layer 17' respectively and the surface of the film 14' is protected with an SiO2 film 20. |
