| 摘要 |
PURPOSE:To remove a thermal nitride film easily by heating silicon in a nitriding atmosphere at a high temperature to form a silicon nitride film, anodic- oxidizing the silicon nitride film by oxalic acid and removing the silicon nitride film through etching by fluoric acid. CONSTITUTION:A silicon substrate 10 is heated at a high temperature of 1,200 deg.C in ammonia gas in order to form the thermal nitride film 11. The silicon nitride film 12 is applied through a CVD method, and a resist film 13 is patterned selectively on the film 12. The silicon nitride film 12 is removed through etching by phosphoric acid, the thermal nitride film 11 is removed through etching by fluoric acid, a field insulating film forming region is exposed, the resist film 13 is removed, a field insulating film 14 is formed, and the silicon nitride film 12 is removed through etching by phosphoric acid. When the thermal nitride film 11 is oxidized in an oxalic acid solution while using the silicon substrate as an anode and etched for approximately three min by fluoric acid, the thermal nitride film 11 is removed completely. |
