| 摘要 |
PURPOSE:To obtain secure ohmic constant and prevent the formation of an inversion layer, without bringing the decrease in gate sensitivity and that in dv/dt characteristic, by a method wherein a P<+> type high concentration layer is formed in the surface of a semiconductor substrate, and the top of the impurity concentration is set inside by outer diffusion. CONSTITUTION:P type insulation isolation layers 22a and 22b are formed in the N type semiconductor substrate 21, and a P type anode diffused layer 24 and a P type gate diffused layer 25 are formed in the surface of the N type base region 23 of the substrate surrounded by the isolation layers. An N<+> type cathode diffused layer 26 is formed in the surface of the gate diffused layer, and a P<+> type high concentration layer 27 is formed on the surface of the substrate by the Ge sealed tube diffusing method. The impurity concentration N of the surface decreases with Ga release, and the top PN is set inside the surface of the layer 27. Accordingly, the decrease in gate sensitivity and that in dv/dt characteristics, etc. can be prevented without losing the ohmic contact property due to the formation of the layer 27 and the effect of preventing an inversion layer. |
