| 摘要 |
PURPOSE:To provide a deep isolation groove of 1mum or less micro width in self- alignment without mask alignment, by the retrogression during oxide film etching, using bird beaks reversely. CONSTITUTION:An SiO2 film 8 is provided on an N type substrate 7, and an N- layer 11 is produced by using an Si3N4 film 9 as a mask; then, a thick SiO2 film 12 is superposed. An Si substrate surface is exposed to the boundary between the films 9 and 12 on the retrogression of the film 12 by anisotropic etching. This exposure depends on the amount of etch-removal of the SiO2. The deep groove 13 is formed by further anisotropic-etching of the substrate 7 and then filled with an insulator 4. Next, the film 9 is removed, and a P-layer 16 is formed by ion implantation of a P type impurity 15 through the film 9. At this time, ions are not implanted to the film 12 on the layer 11 because of the larger thickness of this film, but the N-layer, P-layer, and vertical isolation layer are completed by only a time of photo mask process. |
