| 摘要 |
PURPOSE: A method for forming a contact plug is provided to constantly maintain critical-dimension by simultaneously arranging isolated contact plugs and dense contact plugs on a layout. CONSTITUTION: An insulating layer(205) is formed on a wafer(200). A first region(A) and a second region(B) are defined on the insulating layer. Dense contact plugs are formed in the first region. Isolated contact plugs are formed in the second region. A first trench is formed in the first region using a first mask. A buried insulating layer(210) buries the first trench. The etching selectivity of the buried insulating layer is different from that of the insulating layer. A second trench is formed in the second region using a second mask.
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