Multilevel pedestal for furnace

摘要

A pedestal for use in a high temperature vertical furnace for the processing of semiconductor wafers provides a closure and heat insulation for the lower end of the furnace and is a wafer boat support. The pedestal, comprising quartz-enveloped insulation material, supports a wafer boat at a boat support level and is provided with an upper section disposed above the boat support level. The upper section comprises enveloped insulating material. The envelope of the upper section is also formed of quartz and the insulating material in the upper section has a lower thermal conductance than the insulating material in a lower quartz enveloped section.