In one aspect, the invention includes a semiconductor processing method comprising exposing silicon, nitrogen and oxygen in gaseous form to a high density plasma during deposition of a silicon, nitrogen and oxygen containing solid layer over a substrate.In another aspect, the invention includes a gate stack forming method, comprising: a) forming a polysilicon layer over a substrate; b) forming a metal silicide layer over the polysilicon layer; c) depositing an antireflective material layer over the metal silicide utilizing a high density plasma; d) forming a layer of photoresist over the antireflective material layer; e) photolithographically patterning the layer of photoresist to form a patterned masking layer from the layer of photoresist; and f) transferring a pattern from the patterned masking layer to the antireflective material layer, metal silicide layer and is polysilicon layer to pattern the antireflective material layer, metal silicide layer and polysilicon layer into a gate stack.