Appeal No. 2002-0697
Application No. 09/625,857
the process tube, a coil-shaped heater 22, thermal insulation
material 32, an outer shell 50, and a lid body 26 adapted to
support a quartz boat 24 carrying a plurality of semiconductor
wafers W and to open and close the bottom of the process tube.
Of particular interest is the lid body design shown in
Figure 7 which is constructed to accommodate a shaft 38 for
rotating the quartz boat and wafers. As described by Okase,
[a] circulation path 41 for circulation gas is formed
of a circulation gas introduction opening 42 which is
connected to a circulation gas supply body and which is
provided in the lid body 26 of the dispersion apparatus
S1, and also a pair of components 53 and 54 of a
matching saw-tooth shape in cross-section, via a gap
41a between the shaft 38 and the penetration hole 45 of
the lid body 26. The part of the circulation path 41
for the circulation gas that is in the gap 41a in
contact with the upper part of the shaft 38 is provided
so as to bend along the penetration hole 45 which is
drilled through the lid body 26 and which has a radius
that varies in a step-wise manner. The gas circulation
path also bends along an inner surface portion 41b that
is in contact with the heating gas over a wide surface
area on the inner surface of the lid body 26, and the
hightemperature [sic] gas that passes therealong is led
to a circulation gas exhaust opening 43.
A gap 44 is provided so as to bend between the
inner walls of the process tube 21 as far as the
exhaust openings 25 of the process tube 21, provided
above the circulation gas exhaust opening 43. Thus,
the flow of circulation gas within the gap 44 is
configured so that the circulation gas exhausted from
the circulation gas exhaust opening 43 passes through
this gap 44 and is exhausted from the exhaust openings
25, and thus reaction products do not invade downward
from the gap 44 [column 6, lines 6 through 33].
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Last modified: November 3, 2007