Patent ID: 9543502
Date: 2017-01-10
CPC Classifications: H01L

Claim:
1. A method of forming high density contact array comprising: providing a first dielectric layer; forming a hard mask stack over the first dielectric layer, wherein the hard mask stack comprises first, second and third hard mask layers having materials with mutual etch selectivity with each other and wherein the third hard mask layer is formed over the first dielectric layer while the second hard mask layer is formed in between the first and third hard mask layers; processing the first and second hard mask layers to form high density array of hard mask stack structures by performing a double patterning process, wherein the hard mask stack structures include patterned first and second hard mask layers having a first width F reducing the width of the patterned second hard mask layers to a second width F forming a fourth hard mask layer over the third hard mask layer and surrounding the hard mask posts; and removing the hard mask posts and portions of the third hard mask layer and first dielectric layer underlying the hard mask posts to form high density contact hole array.