Patent ID: 9748139
Date: 2017-08-29
CPC Classifications: H01L

Claim:
1. A method of fabricating a dual damascene structure, comprising: providing a substrate having thereon a first dielectric layer, a second dielectric layer, and a hard mask layer; forming a partial via in the second dielectric layer and the hard mask layer; forming a first photoresist pattern on the hard mask layer, wherein the first photoresist pattern comprises a first trench opening above the partial via and a second trench opening; performing a first etching process to etch the hard mask layer and the second dielectric layer through the first trench opening and the second trench opening, thereby forming a first dual damascene structure comprising a first trench and a first via, and a second trench in the second dielectric layer, respectively; forming a second photoresist pattern on the hard mask layer, wherein the second photoresist pattern comprises a self-aligned via opening having a width larger than a width of the second trench and exposing a part of the second trench and a part of the hard mask adjacent to the second trench; and performing a second etching process using the second photoresist pattern and the exposed hard mask as an etching mask to etch the second dielectric layer through the self-aligned via opening, thereby forming a second dual damascene structure comprising the second trench and a second via under the second trench, wherein a width of the second via equals to the width of the second trench.