| 摘要 |
PURPOSE:To construct transistors for use under high and low voltages in one and the same substrate by a method wherein a high-voltage transistor in a MIS type semiconductor device is so designed that its source and drain regions have low-concentration layers in their circumferences and its gate oxide film is thicker in the vicinity of the gate. CONSTITUTION:The surface of a P-type silicon substrate 1 is subjected to selective oxidation for the formation of an isolating oxide film 2. A silicon nitride film 18 is formed and then removed from the locations planned for drain and source. The exposed silicon of the substrate 1 is implanted with ions, then subjected to heat treatment, for the formation of a low-centration source region 12 and drain region 13. Next, a silicon dioxide film 17 is grown on the source region 12 and drain region 13. A process follows wherein the silicon nitride film 18 is totally removed and a second silicon dioxide film 16 is grown by thermal oxidation. A polycrystalline silicon film is grown for a gate electrode, whereon a photoresist layer 19 is provided. |
