| 摘要 |
PURPOSE:To achieve good electric separation of elements and high integration by a method wherein a semiconductor layer is grown on a semiconductor substrate and an island region is provided in the layer while an insulation film for separation is formed not only in both side ends of this region but also in the bottom. CONSTITUTION:A p<+> type layer 13 is formed on the outer layer of a p type Si substrate 11 by diffusion, and an n type layer 14 having required resistivity is provided on the layer 13 by epitaxial growth, then a p<+> type region 15 reaching the layer 13 is formed at the endmost portions of the layer 14 by diffusion, so that the layer 14 is separated as an islanded region 12. Next, the substrate 11 is dipped in hydrofluoric acid liquid and receives anode formation processing to convert only the layer 13 and the region 15 into porosity Si layer 13' and 15'. Afterward these layers are converted into SiO2 layers 6 and 6' by heat treatment to electrically separate the region 12 not only at its both sides but also at the base by the layers 6 and 6'. After this a p<+> type source region 2 and a drain region 3 are formed on the region 12 by diffusion, and a polycrystalline Si gate 5 is provided on the region 12 which is between the regions 2 and 3 via a gate SiO2 film 4. |
