An interlevel dielectric layer, such as a silicon oxide layer, is
selectively etched using a plasma etch chemistry including a silicon
species and a halide species and also preferably a carbon species and an
oxygen species. The silicon species can be generated from a silicon
compound, such as Si.sub.xM.sub.yH.sub.z, where "Si" is silicon, "M" is
one or more halogens, "H" is hydrogen and x.gtoreq.1, y.gtoreq.0 and
z.gtoreq.0. The carbon species can be generated from a carbon compound,
such as C.sub..alpha.M.sub..beta.H.sub..gamma., where "C" is carbon, "M"
is one or more halogens, "H" is hydrogen, and .alpha..gtoreq.1,
.beta..gtoreq.0 and .gamma..gtoreq.0. The oxygen species can be generated
from an oxygen compound, such as O.sub.2, which can react with carbon to
form a volatile compound.