Optimization of Process Parameter and Temperature Uniformity On Wafers For Rapid Thermal Processing

Abstract

A new strategy based algorithm to optimize process parameter uniformity (e.g.sheet resistance, oxide thickness) and temperature uniformity on wafers in a commercially available Rapid Thermal Processing (RTP) system with independent lamp control is described. The computational algorithm uses an effective strategy to minimize the standard deviation of the considered parameter distribution. It is based on simulation software which is able to calculate the temperature and resulting parameter distribution on the wafer for a given lamp correction table. A cyclical variation of the correction values of all lamps is done while minimizing the standard deviation of the considered process parameter. After the input of experimentally obtained wafer maps the optimization can be done within a few minutes. This technique is an effective tool for the process engineer to use to quickly optimize the homogeneity of the RTP tool for particular process requirements. The methodology will be shown on the basis of three typical RTP applications (Rapid Thermal Oxidation, Titanium Silicidation and Implant Annealing). The impact of variations of correction values for single lamps on the resulting process uniformity for different applications will be discussed.

The effect of patterned susceptor on the thickness uniformity of rapid thermal oxides

“…Therefore, considerable efforts have been undertaken to improve the wafers' temperature uniformity. These efforts include the considerations of the lamp number and location [1]- [3], patterned reflectors [4], [5], individually adjusting the electrical power applied to each lamp [6], [7], system geometry [8], [9], and patterned wafers [10], [11].…”