| 摘要 |
PURPOSE:To obtain the insulating film having a high insulation resistance and the deterioration of which is small by a method wherein a film is formed on a III-V group compound semiconductor substrate in such a manner that the film containing a plenty of oxide of V-group element is formed on the substrate side and the film containing a plenty of oxide of III-group element is formed on the side which comes in contact with the outside air. CONSTITUTION:After the processing strain of an N type InP substrate 1 has been removed, anodic oxide films 2 and 3 are formed in succession using an electrolytic solution of pH 2 and 4 and by having a Pt plate as a cathode, the composition ratio of the film 2 is set at P2O5/In2O3>1, and P2O5/In2O3<1 is set for the film 3. Then, an ohmic electrode 4 of Au-Ge is formed on the back side, and an Al electrode 5 is formed on the above oxide film 3. According to this constitution, as the film 3 of P2O5/In2O3<1 protects the film 2 and maintains an excellent degree of adhesion with metal for outside atmosphere, the insulating film of high insulation resistance having a low deterioration rate can be obtained. In order to change the composition ratio of the oxide, there are such methods wherein an anodic oxidizing solution and the like besides the usage of pH electrolytic solution. Also, the above-mentioned method is not limited for the InP and can be applied to the III-V group compound semiconductors in general. |
