| 摘要 |
A method of forming a dual damascene includes forming first, second and third material layers sequentially over a substrate. The first, second and third material layers have first, second and third thicknesses, respectively. An opening is etched within the first material layer while a portion or all of the thickness of the third layer is simultaneously removed. The ratio of the depth of the opening and the thickness of the third material layer removed, correspond to an etch selectivity of the first material layer and the second material layer. The etching operation may be automatically terminated to produce the opening with a predetermined depth.
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