Analysis on Temperature Distribution in Semiconductor Wafers Heated in a Vertical Diffusion Furnace.

The transient temperature distribution in a row of wafers heating in a vertical diffusion furnace was numericaly calculated as the heating power of the furnace was PID controlled. Radiation heat transfer was combined with axisymmetric unsteady conduction in wafers and the furnace. When the feed forward control of the heating power was used, which meant that the heater temperature was set higher than a given heating temperature during insertion of the wafers into the furnace, the temperature of the wafers reached the heating temperature rapidly. Radiative properties of silicon wafers changed from semi-transparent to opaque at a temperature of 500°C, and the effect of the properties on the temperature distribution in the wafers were calculated. The possibility of occurrence of thermoplastic deformation of the wafers during a withdrawal period was higher than that during an insertion period.