Appeal No. 2006-0291
Application No. 09/820,692
and an oxygen-containing gas is supplied to the plasma etch chamber with the
showerhead electrode to etch openings in the dielectric layer (Brief, pages 2-3).
Representative independent claim 1 is reproduced below:
1. A method of etching a dielectric layer with selectivity to an underlying stop
layer, comprising:
supporting a semiconductor substrate in a plasma etch chamber of a plasma
etch reactor, wherein the plasma etch reactor is a capacitively coupled plasma reactor
having a powered showerhead electrode and/or a powered bottom electrode, the
substrate including a dielectric layer over a stop layer;
supplying an etchant gas to the plasma etch chamber with the showerhead
electrode; and
etching openings in the dielectric layer by energizing the etchant gas into a
plasma state by capacitively coupling RF energy into the plasma etch chamber, the
etchant gas comprising a hydrogen-free fluorocarbon gas represented by CxFy gas
wherein y/x ≤ 1.5, an oxygen-containing gas and optional carrier gas,
wherein the plasma etch reactor comprises a dual frequency capacitively coupled
plasma reactor and RF energy is supplied at two different frequencies to either the
bottom electrode or at different first and second frequencies to the showerhead
electrode and bottom electrode, and
wherein the pressure in the plasma etch reactor is 50 to 100 mTorr and
temperature of the substrate support is +20°C to +60°C.
The examiner has relied on the following references as evidence of obviousness:
Tahara et al. (Tahara) 5,356,515 Oct. 18, 1994
Loewenstein 5,741,396 Apr. 21, 1998
Schmitt 6,228,438 B1 May 08, 2001
(filed Sep. 22, 1999)
2
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