PURPOSE: To eliminate the dulling of a window caused by the adhesion of a product, by drawing a part of a quartz bell jar to a low-temp. part outside another bell jar as a heat screen to constitute a window for measuring a temp.
CONSTITUTION: A part of a quartz bell jar 12 for constituting a reacting oven 1 and preventing the contact of gas with a metal is drawn outside another bell jar 11 as a heat screen. A temp.-measuring window 8 made from a quartz window plate is provided at its top end, and a small amount of inert gas, e.g. He, Ne or Ar, not-containing reactive gas or carrier gas only for reaction is supplied to the temp.-measuring window 8 through a purging opening 18 to it. Consequently, the temp.-measuring window 8 is substantially provided at the side of the reacting chamber in the atmosphere of purge gas other than reactive one, so that its dulling is not formed by the deposition of a product.
AOYAMA TAKASHI
SUZUKI TAKAYA
