Reduction of pattern effects in RTP Centura system

The different optical properties of implanted or patterned areas of production semiconductor substrates result in local temperature differences. This local temperature variation within a wafer may cause unacceptable uniformity of electrical data. RTP systems that use wafer rotation and multipoint temperature control are able to keep overall process uniformity even for within wafer temperature variation. This paper describes a modification to the multi-input, multi-output temperature measurement system used in an Applied Materials Centura RTP system to adapt the temperature control to the wafer pattern. The presented experimental data demonstrates that the modified system is capable of processing any type of patterned wafers while keeping temperature differences between any two zones less than ±2°C. It has been verified in a production environment that this level of temperature control is actually achieved.