Patent ID: 6977210

Claim:
A method for forming a bit line contact hole comprising steps of: providing a substrate; forming a plurality of word line structures on said substrate; forming a nitride layer to cover said word line structures to form a first mediate structure; forming a doped dielectric layer on said first mediate structure; defining a position on said doped dielectric layer where the contact hole is to be formed; removing said doped dielectric layer except for the portion at the position where the contact hole is to be formed to form a second mediate structure; forming a liner nitride layer on the periphery of the retained doped dielectric layer; forming a non-doped dielectric layer on said second mediate structure; and removing the retained doped dielectric layer by using an etchant having a high selectivity to the doped dielectric layer with respect to the non-doped dielectric layer to form the contact hole.