Appeal 2007-1269
Application 10/636,468
5. Liu describes a metrology method of measuring film thickness in a
semiconductor manufacturing process. (Liu, paragraph [0001].) The
method may be used for determining the endpoint of a chemical
mechanical polishing (CMP) process. (Liu, paragraph [0001].)
6. In one embodiment of Liu, a reference wafer with a reference oxide
layer thickness is included in a polishing process. (Liu, paragraph
[0026].) After a first polishing time period, the reference wafer is
removed, a Fourier Transform Infra-Red (FTIR) measurement is
taken, and both the removed oxide layer thickness and the remaining
oxide layer thickness are determined. (Liu, paragraph [0026].) A
polishing rate is determined so as to project the time period remaining
to reach an endpoint of the polishing process. (Liu, paragraph
[0026].) The reference wafer may then be returned for additional
polishing time periods. (Liu, paragraph [0026].)
7. In one embodiment of Liu, a monitor wafer is "periodically removed
following a CMP polishing period for at least one FTIR measurement
to determine an oxide layer thickness and material removal rate."
(Liu, paragraph [0027].) Liu explains that:
A polishing rate may be determined following the
first FTIR measurement after beginning the CMP
polishing process with reference to an initial FTIR
measurement made prior to beginning the CMP
process to determine an initial thickness. For
example, a removed thickness portion of the oxide
layer is determined following an initial CMP
polishing period and divided by an initial polishing
time to determine a material removal rate. The
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