A method is described for forming a trench in a semiconductor substrate, which
has a silicon layer, an oxide layer overlying the silicon layer, and a nitride
layer overlying the oxide layer. The method includes etching the nitride layer
to a nitride end point using a nitride etching chemistry, which includes a fluorinated
hydrocarbon, oxygen, and an inert gas selected from the group consisting of neon,
argon, krypton, xenon, and combinations thereof. Methods of making semiconductor
devices, methods of reducing defects in semiconductor devices, and silicon wafers
having trenches and isolation regions formed by the above-mentioned methods for
forming a trench are also described.
