TRENCH ISOLATION STRUCTURE, SEMICONDUCTOR DEVICE HAVING THE STRUCTURE, AND TRENCH ISOLATION METHOD

摘要

PURPOSE: A trench isolation structure, a semiconductor device having the structure, and a trench isolation method are provided to improve reliability of a transistor and a gate oxide layer by rounding upper corners of a trench and by increasing a thickness of the gate oxide layer at the upper corners. CONSTITUTION: A pad oxide layer and a pad nitride layer are formed on a substrate(40) and etched to form the trench in the substrate(40). An inner oxide layer(48) is then formed on inner walls of the trench, and a silicon nitride liner(50) is formed thereon. A CVD oxide layer(52) is then formed enough to fill the trench and planarized. Thereafter, the pad nitride layer is removed, and simultaneously the nitride liner(50) is partially etched. Accordingly, when the gate oxide layer(54) is formed after a removal of the pad oxide layer, the gate oxide layer(54) has a relatively greater thickness at the upper corners of the trench. Then, a gate electrode(56) is formed on the gate oxide layer(54).