| 摘要 |
PURPOSE:To perform a dielectric isolation of a large-area N type region without causing a warpage of a substrate by preventing porous Si from proceeding beyond the part of N type buried layer hydrofluoric acid anodizing reaction. CONSTITUTION:An N type diffusion layer 11 is formed in the predetermined part of a P type Si substrate 1. When a P type layer is epitaxially grown on that, the N type diffusion layer 11 becomes an N type buried layer. Then an N type region 8 is formed in a part 12 of the P type layer. By hydrofluoric acid anodizing reaction, a porous Si layer 9 is cut off when it reaches the N type buried layer 11 and it does not proceed in a depth direction. A depth of the layer 9 is up to the part of N type layer 11. Next, by thermal oxidation or the like, the porous Si layer 9 becomes insulating Si dioxide and the N type region 8 is isolated by this insulating layer. |
