Patent ID: 9679804
Date: 2017-06-13
CPC Classifications: H01L

Claim:
1. A method comprising: forming a carbon-containing layer with a carbon atomic percentage greater than about 25 percent over a first hard mask layer; forming a capping layer over the carbon-containing layer; forming and patterning a first photo resist over the capping layer; etching the capping layer and the carbon-containing layer using the first photo resist as a part of a first etching mask; removing the first photo resist; forming and patterning a second photo resist over the capping layer; etching the capping layer and the carbon-containing layer using the second photo resist as a part of a second etching mask; removing the second photo resist; etching a third photo resist under the carbon-containing layer using the carbon-containing layer as a third etching mask; etching a dielectric layer underlying the third photo resist to form via openings, wherein the third photo resist is used as a part of a fourth etching mask; and filling the via openings with a conductive material.