Importance

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Abstract

A thermal treatment boat having a plurality of annular, coaxial, spaced apart bands having substantially the same inner diameters. The bands are separated by a band spacing distance of from about 3.8 to 12.7 mm, each of the bands having a height, Height.sub.Band, in mm according to the equation: ##EQU1## wherein Height.sub.Band is always.gtoreq.wafer thickness; ColumnHeight is the total height of the treatment boat, mm; BandSpacing is the band spacing distance between adjacent bands, mm; and NumberBands is the total number of bands in the treatment boat. Preferably the NumberBands is from about 12 to about 100. Each band includes wafer support means for supporting a wafer therein at a position which is substantially centered between the upper edge surface and said lower edge surface thereof, the wafer support means in one embodiment including at least three inwardly extending projections. Each band is sized to provide a radial clearance between the outer edge of the wafer and the inner surface of the respective band within the range of from about 1.5 to 6.3 mm. In the process, the heat provided by the heater is sufficient to raise the temperature of the wafers from 21.degree. C. up to 1100.degree. C. at a rate of from 50.degree. C./min to 100.degree. C./min without causing mechanical damage due to induced stresses in the wafers.

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First Claim