| 摘要 |
PURPOSE:To decrease the parasitic resistance of the isolation layers and to prevent the side surfaces from being etched when the connection holes are opened by a method wherein a P type impurity is diffused in the region isolated by the P type layers on the P type Si substrate when the P type base layer is formed in the region. CONSTITUTION:An N type epitaxial layer 3 on a P type Si substrate 1, wherein an N<+> type layer 2 is buried, is isolated by P type layers 4. In case of providing a P<+> type base layer 5a in the N type layer 3, windows are opened on the surface oxide film, a P type impurity is diffused in the isolation layers 4 and P<+> type earth electrode connecting layers 5b are formed. According to this constitution, the impurity concentration of the isolation layers 4 increases, the parasitic resistance of the layers 4 decreases, and moreover, the oxide film on the isolation layers 4 is film, which is formed after the base diffusion process is performed, and the film thickness thereof is the almost same one as that of the oxide film on the other parts having no oxide film when the isolation layers are formed. As a result, when the connecting holes are opened, the degree of an etching, which exerts on the side surfaces, can be suppressed and the processing accuracy can be improved. |
