Energy saving in semiconductor fabs by using vacuum insulator

This paper describes the heat insulation of newly developed vacuum insulators of vertical furnaces for 300 mm silicon wafer oxidation process. The thermal conductivities of several core materials at low vacuum (0.1 Pa) were shown to be about 1/3 of those measured at atmospheric pressure. The new insulator consists of a metal casing and a core material of heat resistant type that is enclosed in the former tightly enough to maintain the vacuum state once established. The amount of heat radiation from the vertical furnace equipped with the vacuum insulator thus developed is experimentally found to be less than 1/4 of the conventional system. This means that the amount of energy transfer to clean room air could be reduced to less than 1/4 that of the present casing by employment of the vacuum insulator packed with the core materials.