Patent ID: 6258726
Filing Date: 2001-07-10
Classification: H01L

Abstract:
A method for forming an isolation film, comprising:(a) forming a mask including a first mask layer pattern and a second mask layer pattern on a semiconductor substrate, the second mask layer pattern being on the first mask layer pattern;(b) forming a trench in a portion of the substrate exposed by the mask;(c) forming a first insulating film which fills the trench and covers the mask;(d) etching the first insulating film until a sidewall of the second mask layer pattern is exposed, the remaining portion of the first insulating layer becoming a first isolation film;(e) forming a first spacer on the sidewall of the second mask layer pattern, wherein step (e) comprises:(e1) forming a second insulating film on the substrate after step (d), so that the second insulating film covers the first isolation film and the second mask layer pattern; and(e2) anisotropically etching the second insulating film so that the first isolation film and the second mask layer pattern are exposed;(f) etching the first isolation film until a top surface of the first isolation film is lower than that of the first mask layer pattern;(g) removing the second mask layer pattern and the first spacer; and(h) removing the first mask layer pattern and forming a second isolation film having a second spacer connecting an active region of the substrate to the second isolation film, on the upper sidewall of the trench, wherein the second spacer reduces the gradient between the active region and the first isolation film.