METHOD FOR FORMING ISOLATION LAYER OF SEMICONDUCTOR

摘要

PURPOSE: A method for forming an isolation layer of a semiconductor is provided to prevent a moat phenomenon. CONSTITUTION: A thin pad oxide layer is formed on a silicon substrate(10) and a nitride layer is doped on the oxide layer. A photoresist pattern covers on the nitride layer. Etching makes the first trench from the nitride layer. After removing the photoresist pattern, a side wall spacer is generated on the side of the trench. The first device separation oxide(22) is produced on the exposed substrate between the spacers. Using a blanket etching method, the first device separation oxide(22) is etched selectively including the substrate(10) to create the second trench. The trench is filled with a gap filling oxide(26') and annealing process is executed to increase density of the oxide(26'). The structure is flattened by a CMP(Chemical Mechanical Polishing) method. A device isolation layer is completed after removing the nitride layer and the pad oxide layer.