| 摘要 |
PURPOSE:To shorten the manufacturing process of the title semiconductor device and to cur down its cost by a method wherein the ion-implanting apertures on all transistors, for which threshold voltage is going to be set, are formed by conducting a photolithographic method, and then ions are implanted. CONSTITUTION:An aperture part 6 is away from the end parts of source and drain regions 4a and 4b by a distance (x). In this case, the distance (x) is selected in such a manner that a threshold value can be set at the prescribed value by controlling the density of ions located on the lower part of an electrode 3 using the semiconductor substrate 1 located between the source and drain regions 4a and 4b of a transistor by implanting ions into the aperture part 6 formed corresponding to a mask pattern 5. Also, in order to form another transistor having a threshold value simultaneously, a mask pattern 5, having the end part at the point of distance (x) corresponding to the above-mentioned threshold value, is formed. The aperture part 6 corresponding to all mask patterns 5 is formed by conducting a photolithographic method. Then, a mask ROM is obtained by implanting ions at a prescribed density. As a result, the process of manufacture can be cut down, and the reduction in cost can also be accomplished. |
