| 摘要 |
PURPOSE: A twin well formation method is provided to improve a reliability of semiconductor devices by improving a step coverage. CONSTITUTION: A first insulating pattern and a first buffer insulator are sequentially formed on a semiconductor substrate(10). The first impurity ions are implanted into the substrate(10) using the first insulating pattern as a mask, thereby forming a first well formation region. After sequentially forming and patterning a second insulating layer and a planarized layer, the exposed first insulating pattern is then removed and a second buffer insulator formed on the exposed substrate(10). The second impurity ions are implanted into the substrate(10) using the second insulating layer as a mask, thereby forming a second well formation region. After removing the second insulating layer, the first and the second buffer layers, twin wells(40,70) are formed by annealing the resultant structure.
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