METHOD FOR FORMING ISOLATION LAYER OF SEMICONDUCTOR DEVICE USING POLYSILICON LAYER AS SUBSIDIARY LAYER

摘要

PURPOSE: A method for forming an isolation layer of a semiconductor device is provided to prevent damage of pad patterns in reverse etch-back processing by using a polysilicon layer as a subsidiary layer. CONSTITUTION: A pad pattern including a pad oxide layer(33) and a pad nitride layer(35) is formed on a silicon substrate(31). A subsidiary layer(37) made of a polysilicon layer is formed on the pad nitride layer. A trench(41) is formed by selectively etching the subsidiary layer, the pad nitride layer, the pad oxide layer and the substrate. A sidewall oxide layer(39) is formed on the trench. A gap-fill oxide layer(43a) is filled in the trench and removed selectively by reverse etch-back processing, thereby forming an isolation layer.