METHOD OF FORMING A DEVICE ISOLATION AREA AND METHOD OF FORMING AN IMAGE DEVICE USING THE SAME

摘要

A method for forming an isolation region is provided to control generation of voids and seams in an isolation layer filled in a trench by forming a trench having a reduced aspect ratio as compared with a conventional technique. A hard mask pattern is formed on a substrate(100) wherein a first pattern and a second pattern thicker than the first pattern are stacked in the hard mask pattern. By using the hard mask pattern as an etch mask, the exposed substrate is etched to form a first trench between the hard mask patterns. A sacrificial layer is formed on the hard mask pattern to fill the inside of the first trench. The upper part of the sacrificial layer and the second pattern are removed to form a sacrificial layer pattern. The sacrificial layer pattern is completely removed to form a second trench having a shallower depth than that of the first trench. An isolation layer is formed to completely fill the second trench. The first pattern can be made of a nitride and the second pattern is made of an oxide. The sacrificial layer can be USG(undoped silicate glass) an ALD(atomic layer deposition) oxide layer or BPSG(boron phosphorous silicate glass).