| 摘要 |
PURPOSE: A method for forming a trench is provided to prevent trench corners from being overetched due to the reduction of the etching rate of a trench side by remarkably increasing the crystallization of the trench through two staged annealing process. CONSTITUTION: First, a pad oxide(20) and nitride(30) are stacked on a Si-substrate(10). Then, a trench is formed by etching the pad oxide, nitride, and Si-substrate with predetermined depth. Next, a liner oxide(40) is formed on the Si-substrate having the trench. Then, the trench is buried with silicon oxide, which is then planarized until a surface of the nitride is exposed. Next, the resultant is annealed from a room temperature to 900-1000 deg.C and then is secondarily annealed from a room temperature to 1100-1150 deg.C. Finally, the nitride and pad oxide are removed to form an isolation layer(50) of trench structure.
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