| 摘要 |
PURPOSE:To prevent one PN junction from breaking down owing to the breakdown of the other by making two PN junction parts away in three dimensions, in a memory unit which is stored with information by making either PN junction, provided into the semiconductor, destructive or undestructive. CONSTITUTION:Onto N-type or P-type Si substrate 13, SiO2 film 14 is bonded, and on the entire surface, N-type poly-crystal Si layer 15 is deposited and selectively etched into polycrystal 15' in a mutually-separate island shape, which is surrounded with SiO2 film 16. Next, P-type region 17 is formed by diffusion inside of poly- crystal layer 15' exposed by providing an window to the top surface of film 16, and P-type poly-crystal Si layer 18 is bonded meeting region 17 and covering film 16. After poly-crystal layer 18 adhering to the flank of the island region is removed, N-type region 19 is formed by diffusion where region 17 of poly-crystal layer 18 remaining on the surface does not correspond, and Al wiring 20 is bonded here. In this way, the 1st and 2nd PN junction parts are made in poly-crystal layers 15' and 18 and probability that the junction is broken at the time of information writing to a memory cell is decreased. |
