| 摘要 |
The invention provides a method for forming a via. A first dielectric layer is formed on a substrate. A conductive structure is formed in the first dielectric layer. A second dielectric layer is formed on the first dielectric layer and conductive structure. A first etching step is performed by using a first etching mixture to form a first via in the second dielectric layer. A second etching step is performed by using a second etching mixture to form a second via under the first via. The second via exposes at least a top surface of the conductive structure. An etching rate of the second etching step is slower than the first etching step.
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