Modelling and Control of a Diffusion/LPCVD Furnace

摘要

A study is made of the heat transfer inside a cylindrical resistance diffusion Low Pressure Chemical Vapor Deposition furnace, aimed at developing an improved temperature controller. A model of the thermal behavior is derived which also covers the important class of furnaces equipped with semi-transparent quartz process tubes. The model takes into account the thermal behavior of the thermocouples. It is shown that currently used temperature controllers are highly inefficient for Very Large Scale Integration applications. Based on the model, an alternative temperature controller of the Linear, Quadratic, Gaussian type is proposed which features direct wafer temperature control. Some simulation results are given. (Copyright (c) 1988 by Faculty of Technical Mathematics and Informatics, Delft, The Netherlands.)