PURPOSE: To prevent a substrate from being damaged by implanting an impurity to be used to isolate a p-n junction before the substrate is ground and polished after an epitaxial process.
CONSTITUTION: The main surface 100 of an Si single-crystal substrate 1 of an n-type conductivity type is oxidized; an oxide film 2 is formed; the oxide film is removed selectively. Then, V-shaped isolation grooves 3 are formed by a selective etching operation by making use of the remaining oxide film as a mask. Then, an oxidation operation is executed again; an oxide film 4 is formed; one part of the oxide film 4 constituting vertical-type single-crystal regions 51, 52 is removed; then, Si is grown by a vapor epitaxial growth operation; single- crystal Si 51, 52 are grown in parts where the oxide film 4 has been removed; polycrystalline Si 7 is grown in parts where the oxide film has been left. Then, a p-n isolation is executed by diffusion of aluminum; while Al inside the polycrystalline Si 7 is diffused a little in the single-crystal regions, it reaches the oxide film for isolation use; in addition, Al is diffused from the polycrystalline region to the single-crystal regions; a junction for p-n isolation use is formed; the two insulated and isolated vertical-type single-crystal regions and a single- crystal island which has been insulated and isolated by the oxide film are united. By this setup, a p-n junction for isolation use can be executed in a state that the substrate is thick; accordingly, a yield is enhanced.
Sekine, Shigeki
Ishikawa, Toru
Sugawara, Yoshitaka
