Method of manufacturing semiconductor structure

Abstract

A method of manufacturing a semiconductor structure includes forming bit line structures on a substrate; forming a dielectric layer on the substrate and between the bit line structures; forming a layer stack including a plasma treated oxygen-rich ARC layer and a silicon-rich ARC layer on the dielectric layer; forming a patterned mask layer including a mask feature and an opening on the layer stack, the opening has a first width smaller than a pitch between adjacent two of the bit line structures; trimming the patterned mask layer to enlarge the opening such that the opening has a second width greater than the first width; patterning the layer stack by using patterned mask layer as a mask after trimming the patterned mask layer; and etching the substrate to form a contact hole between the bit line structures by using the patterned layer stack as a hard mask.