| 摘要 |
PURPOSE:To obtain an element isolating layer having a fine width, by providing a first mask on an SiO2 film, coating the side surface by a second mask, opening a hole in an SiO2 film, and performing selective oxidation. CONSTITUTION:On a thermal oxide film 2 on a P type Si substrate 1, Si3N4 3 and SiO2 4 are laminated. A resist mask 3 is applied. Dry etching is performed and a first mask 4a is formed so that l1=l2=1mum is obtained. SiO2 6 is overlapped, and RIE is performed. A second mask 6a is formed on the side surface of the mask 4a. After B ions are implanted, the masks 4a and 6a undergo wet etching and the masks are removed. Then the side surface of the SiO2 under the Si3N4 mask 3a is etched by about 0.02mum. Then selective oxidation of the substrate 1 is performed, and an isolating layer 8 is formed. Bird's beaks 9 are formed on both sides. The width l5=0.4mum of the window of the mask 3a is added to the beak widths 0.3mumX2 on both sides, and the isolating layer 8 having the width 1mum is obtained. Therefore, the width of an active region 10 of 1mum is secured, the element is miniaturized and high degree of integration can be accomplished. |
