Appeal 2007-0908
Application 10/152,077
e.g., pure water 70, is supplied to the wafer near its center and spun off.
(Ueno at 10:55-65.)
29. Ueno teaches that two or three seconds before the supply of pure
water is stopped, an IPA vapor 80 is supplied from nozzle 8 onto the wafer
near its center for 10 seconds. (Ueno at 10:66 to 11:5.)
30. According to Ueno, the wafer W is rotated at 300 rpm during the
etching and during the supply of the pure water and the IPA vapor. (Ueno at
11:18-19.)
31. Then, after the IPA vapor is stopped, the wafer is spun at 300 rpm for
one second, then at 3000 rpm for four seconds, and then at 5000 rpm for five
seconds. (Ueno at 11:20-21.)
32. Ueno explains earlier in its disclosure that:
where the rotation speed is too high at the beginning of the spin
drying operation just after the IPA liquid supply, the pure water
and IPA liquid scattered by the centrifugal force are splashed
back onto the wafer W, and the number of adhered particles is
increased. For this reason, it is preferable to initially rotate the
wafer W at the first rotation speed to make big drops spun [sic:
spin] off, then at the second rotation speed to make small drops
sp[i]n off.
(Ueno at 9:57-64.)
33. Ueno teaches further that "[a]n inactive gas, such as N2 may be
sprayed onto the surface of the wafer during the spin drying operation" in
order to shorten the drying time. (Ueno at 11:38-40.)
34. Ueno also teaches that, as the IPA vapor, "[i]t is also possible to use a
mixture of IPA vapor and diluting N2, having a temperature of from room
temperature to a boiling point [of IPA, ~82°C]." (Ueno at 11:45-47.)
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