| 摘要 |
PURPOSE:To obtain a passivation layer easily by a method wherein a counter conductive domain is provided on a substrate having a selective diffused domain more shallowly than said domain, the diffused domain is anodized and converted into a porous insulator domain through insulating treatment, and the substrate is covered with an insulated film on the surface. CONSTITUTION:A low specific resistance of N<+> selective diffused domain 17 is formed on a high specific resistance of N<+> N<-> substrate 100 with a mesa type NPN transistor. Next, a P type base domain 3 is diffused more shallowly than said domain. The substrate is anodized in a 49% fluoric acid with platinum as a cathode to convert the N<+> domain 17 into a porous Si domain 18. Then, the substrate is heated in an oxidizing or nitrifying atmosphere to insulation, the domain 18 is converted into an insulator domain working as a passivation layer, and an insulated film 20 is formed on the substrate surface. An emitter domain 5 and electrodes 8, 9, 10 are provided with the insulated film as a mask, and an insulator domain 19 is cut at the center to obtain a mesa type transistor. The passivation layer can thus be formed easily. |
