| 摘要 |
PURPOSE:To obtain a thick protective film and heighten pressure resistance by a method wherein PN-junction exposing is a mesa portion is coated with polycrystal Si films, the films are thermally oxidized and the whole surface is covered with a glass layer when the protective film is formed to the PN-junction. CONSTITUTION:PN-junction 2 is made up on a surface layer of a Si substrate 1 by means of selective diffusion, and a Si3N4 film 4 is laminated and coated on a SiO2 film 3 generated at that time. A photo-resist layer 5 is applied on the film 4, a portion on a portion where a mesa is formed is removed by exposure, these layers and junction are etched using the residual layer 5 as a mask, and mesa portions 6 are formed. The layer 5 is removed, and polycrystal Si films 7 are built up only to the bottom and side-walls of the mesa portions 6 by means of selective anodic oxidation. The films 3, 4 are removed, a surface of the substrate 1 and the films 7 are thermally oxidized, a thin SiO2 film is formed on the surface of the substrate 1 and thick SiO2 films on the surfaces of the films 7, and the whole surface is coated with a glass layer 8. Thus, the thickness of a protective film for the mesa portion can approximately be trebled as compared with the conventional films, and pressure resistance is heightened only by the thickness. |
