MANUFACTURING METHOD OF TRENCH ISOLATION

摘要

PURPOSE: A trench isolation method is provided to prevent a parasitic capacitance generated at an upper edge of a trench. CONSTITUTION: The trench isolation method comprises the steps of: sequentially forming first and second insulation layers on a semiconductor substrate; over-etching a predetermined thickness of the substrate when sequentially etching the second and first insulation layers by using as a mask a photoregist layer pattern for defining active and non-active regions; exposing a part of the substrate of the active region by undercutting a part of the first insulation layer in both sides of the etched substrate of the non-active region; rounding an edge of the exposed substrate of the active region while forming a trench by etching the substrate in which the second insulation layer is used as a mask; forming a third insulation layer which compensates for damage to both sides and a bottom surface of the trench and the rounded part of the substrate; forming a fourth insulation layer on the second insulation layer to fill up the trench perfectly; forming a trench isolation by etching the fourth and second insulation layer until a part of the second insulation layer is exposed; and sequentially eliminating the second and first insulation layer in both sides of the trench isolation.