| 摘要 |
PURPOSE:To obtain an IC device which has small parasitic capacity by simultaneously forming flatly an element isolating region of narrow width and a field region of wide width. CONSTITUTION:An N<+> type layer 2, an N<-> type layer 3, an oxidized film 3, a nitrided film 5, a polysilicon film 6, a nitrided film 7, and a CVD oxidized film 8 are superposed on a P<-> type Si substrate 1, resist masks 9, 9' are formed, a hole 10 is opened, and a film 8 is etched at the side. A resist is removed, the layer 6 is selectively altered on an oxidized film 11, a hole 12 is formed, and a vertical groove 13 which reaches the substrate 1 is formed by an RIE method. Then, the films 7-4 on a field forming region are selectively etched subsequently to the film 8, and the film 11 is further removed. An oxidized film 14 and a nitrided film 15 are superposed, etched by the RIE method, and a polysilicon 16 is thickly accumulated. Then, the layer 15 is etched to stop the surface in the depth of 1/2 or less of a groove from the surface of the layer 3. Then, the surfaces of the layer 3, 16 becomes substantially equal. The polysilicon 16 and the exposed epitaxial layer 3 in the groove are converted to an oxidized film 17, and the surface is flattened. Then, the films 5, 4 are removed, and an element formed. No lateral expansion of the layer 2 occurs, and a parasitic capacity between element region substrates is extremely small.
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