| 摘要 |
First of all, a semiconductor substrate is provided, the semiconductor substrate has a dielectric layer thereon. Then a photoresist layer is formed and defined on the dielectric layer. Next, an etching process is performed by the photoresist layer as an etched mask to form a trench in the dielectric layer, wherein the etchant of the etching process comprises a mixing gas with a C4F6 gas or a CH2F2 gas, such as C4F6/CH2F2/Ar/O2 or C4F6/CH2F2/Ar/O2/CF4 or C4F6/CH2F2/Ar/O2/C2F6, accordingly, the etching capability of the etchant and the etching selectivity between the dielectric layer and the photoresist layer can be raised. Finally, the photoresist layer is removed to form the contact window or the via hole with high accurate critical dimension.
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