| 摘要 |
PURPOSE:To cancel the short-channel effect, to improve WRITE efficiency, and to realize high-speed operations by a method wherein a region for a field effect transistor channel is so designed that impurity concentration is higher inside the region than in the locations in the vicinity of the primary surface of a semiconductor substrate. CONSTITUTION:A region for an FET channel in a semiconductor region 14 is so designed that the concentration of impurity is higher inward than on the primary surface of a semiconductor substrate 5. The semiconductor region 14 is formed by ion implantation whereby a P type impurity is selectively introduced after the formation of insulating films 8, 8A. For example, an ion implantation technique is used whereby B ions of 1X10<12>atoms/cm<2> are introduced by 150keV energy. The maximum impurity concentration rests inside the substrate 5 at a level not less than 0.1mum deep from the surface. Accordingly, the semiconductor region 14 is positioned not less than approximately 0.1mum deep. |
