The Effect of Lamps Radius on Thermal Stresses for Rapid Thermal Processing System

Abstract

The concept of rapid thermal processing has many potential applications in microelectronics manufacturing, but the details of chamber design remains an active area of research. In this work the influence of lamps radius on the thermal stresses in a wafer during the cooling process is studied in detail. Since the equations governing the present thermal-elastic system are coupled in nature, the solution for the temperature and stresses must proceed simultaneously by using a fully implicit finite difference method. After the thermal stresses are obtained, the optimum lamps radii for various heights of the chamber under the constant power ramp-down control scheme are determined based on the maximum shear stress failure criterion. The shortest cooling time that can significantly reduce the thermal budget and dopant redistribution is also predicted by applying the maximum stress control scheme. The result obtained is useful in the design of a reliable rapid thermal processor based on a more practical consideration, thermal stress.