Appeal No. 2000-2093 Page 6
Application No. 08/730,385
by the claim. According to the appellant, Shendon provides a rotational compensation
assembly which is intended to stop rotation of the wafer during the polishing process, thus
limiting the movements to rotation of the platen and orbiting of the wafer. We do not agree
with the appellant on this point.
Using Figure 2 as an illustration, Shendon discloses a polishing pad 22 mounted on
a rotatable platen 16. Mounted on the bottom of a rotatable shaft 56 positioned above the
platen is a cross arm 60 from which extends a drive shaft 64 upon the end of which the
substrate (wafer) carrier 24 is mounted. Rotation of shaft 56 by a first drive belt 52 causes
carrier 24 to orbit about shaft 56. Also attached to drive shaft 64 is a pinion gear 74 that
has teeth on its outer periphery that mesh with teeth on the inside of the outer hub 59 of
transfer case housing 58. Outer hub 59 is rotated by a second drive belt 90. Shendon
teaches that “[t]he carrier may be controlled to orbit the substrate without rotation or to
rotate the substrate at a desired velocity as it is orbited” (column 3, lines 19-21). To
accomplish this, as is explained in column 7, beginning at line 49, the orbiting substrate
may be rotated, or may orbit without rotation, by selectively rotating the
housing 58 with the motor 90. By rotating the orbiting substrate 12 at the
same speed as the polishing pad 22, the cumulative motion between the
polishing pad 22 and every point on the substrate 12 may be uniformly
maintained. Therefore, over-polishing attributable to differential cumulative
motions on different areas of the substrate is eliminate [sic]. Additionally, the
rotational speed of the substrate may be varied from the rotational speed of
the polishing pad 22 to increase the relative motion between the edge of the
substrate and the polishing pad 22, as compared to the center of the
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