Heat treating device

Claim 1

A heat treating device comprising: a wafer boat for holding objects to be treated; a processing vessel including an inner tube for receiving the wafer boat to expose the objects to be treated to processing gases for a heat treatment, and an outer tube disposed concentrically with the inner tube and spaced from the inner tube by a set gap, the processing vessel defining an opening at a bottom thereof; processing gas introduction nozzles inserted into the interior of the processing vessel for introducing processing gases into the processing vessel; a vertically movable cap for openably closing the opening of the processing vessel; and a heat retention cylinder connected to the cap, on which the wafer boat may be mounted, the heat retention cylinder having a heat reserving cylinder body including a ring-shaped heat reserving portion defining a gas passage in the center thereof and a plurality of legs provided on an underside of the ring-shaped heat reserving portion, and a heat retention cylinder cover covering the heat reserving cylinder body, the heat retention cylinder cover defining therein a gas introduction opening proximal at least one of the gas introduction nozzles, and a gas release opening at a top of the heat retention cylinder cover, the gas introduction opening being connected to the gas release opening the gas passage formed in the center of the ring-shaped heat reserving portion.