| 摘要 |
PURPOSE:To form a highly reliable element separating region without damaging a silicon substrate by removing a nitrified film by heated phosphoric acid after selective oxidization. CONSTITUTION:An oxidized silicon film 2 and a nitrified silicon film 3 are formed on a silicon substrate 1 one after the other, and selective oxidization is carried out after the formation of an element separating region pattern. Oxidized silicon 6 formed through the selective oxidation eats into a portion under the nitrified silicon film 3, and a nitrified silicon film 8 is formed on the surface of the silicon substrate in this portion. In addition, an oxidized silicon film 9 is formed by the oxidation of the nitrified silicon films. After the oxidized silicon film 9 is removed through etching with a fluoric acid solution, the nitrified silicon film 3 is selectively removed by heated phosphoric acid (phosphoric acid anhydride heated to about 180 deg.C). By so doing, even if any chance the silicon substrate is exposed, it is not etched, so that disconnection is prevented as no concaved silicon portion is produced. |
