| 摘要 |
PURPOSE:To effectively remove a contaminated layer and a damaged layer by a method wherein a semiconductor substrate is plasma-doped with ammonia after a trench is made and before a sacrifice oxide film is formed. CONSTITUTION:A silicon oxide film 23 is formed on a substrate 21; a resist is coated to obtain a resist pattern 25. The silicon oxide film 23 is etched by making use of the pattern as a mask; the resist is stripped off to obtain a mask 23a for trench etching use. Then, an exposed part of the substrate 21 is etched to make a trench 27. During this process, a surface-contaminated layer 29 is formed on sidewalls and the bottom of the trench 27, and a damaged layer 21 is formed in the walls. The silicon substrate in which the trench is formed and whose O2 ashing operation and acid treatment are finished is plasma-doped with ammonia; a sacrifice oxide film 35 is formed inside the trench at a temperature of 900 deg.C or higher and in an atmosphere of dry oxygen or in an atmosphere of oxygen containing a vapor. Then, the sacrifice oxide film 35 is removed; the substrate 21, having the desired trench 27, in which the contaminated layer and the damaged layer are removed is obtained. |
