Appeal No. 2001-2244
Application No. 09/625,144
BACKGROUND
Appellants’ invention relates to a process for selectively etching or patterning a
structure that includes doped silicon dioxide. The process is effected with an etchant that
comprises C2HxFy, where x is an integer from 3 to 5 and y is an integer from 1 to 3, and
x+y=6. The etchant is formulated to etch doped silicon dioxide at a rate faster than the etch
stop. Both undoped silicon dioxide and silicon nitride may be used as an etch stop because
such materials are etched at a lower rate than the doped silicon dioxide. (Specification, p.
4). Claims 1 and 8, which are representative of the claimed invention, appear below:
1. A process for selectively etching a structure comprising doped silicon
dioxide, the process comprising:
exposing the structure to an etchant comprising C2HxFy, where x is an integer
from 3 to 5, inclusive,
y is an integer from 1 to 3, inclusive and x+y=6; and
removing the structure down to an etch stop adjacent the structure and
comprising undoped silicon dioxide, said removing being effected without
substantially removing said etch stop.
8. A method for patterning doped silicon dioxide, comprising dry etching at
least one exposed region of the doped silicon dioxide with an etchant
comprising C2HxFy, where x is an integer from 3 to 5, inclusive, y is an integer
from 1 to 3, inclusive, where x+y=6, said etchant being formulated to etch
doped silicon dioxide at a faster rate than undoped silicon dioxide and than
silicon nitride.
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