| 摘要 |
A method for forming a shallow trench isolation structure comprising the steps of sequentially forming a pad oxide layer and a mask layer over a substrate, then patterning the mask layer and the pad oxide layer. Next, an opening is formed in the mask layer, wherein the sidewall of the opening in the mask layer forms a sharp angle with the substrate layer below. Thereafter, the substrate is etched from the opening down to form a trench. In a subsequent step, insulating material is deposited into the trench forming an insulating layer rising to a level higher than the mask layer, and accompanying by the formation of a protuberance at the side of the insulating layer. Subsequently, the mask layer is removed, and then portions of the pad oxide layer is removed to form a spacer on the upper side of the insulating layer. Finally, the pad oxide layer above the substrate is removed to complete the formation of the shallow trench isolation structure. Due to the presence of a spacer, resistance against subsequent etching is increased at the junction between the trench insulating layer and the substrate layer. Thus, kink effect caused by the over-etching of the insulating layer is prevented.
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