| 摘要 |
PURPOSE: To provide a semiconductor device and its manufacture, which has a double well construction and is capable of simplifying the processes, by reducing the intervals between a nearby circuit P well and a memory cell P well, and by introducing a self-matching self-aligned well process and reducing photolithographic processes required for well formation. CONSTITUTION: In a semiconductor device where a P-well having a concentration higher than that of the silicon substrate 110 is formed on a P-type silicon substrate 110 and an N-well is formed so as to surround the P-well, the concentration of a region 115 existing in the lateral direction of the substrate surface at a N-well portion is made higher than the concentration of an N-type well region 113 in a lower portion of P-well. |
