Modelling Flash Lamp Annealing
The use of silicon carbide (SiC) in the semiconductor industry is on the rise. In an attempt to bolster Europe's position in this rapidly developing market, the GROWTH Programme funded a consortium of over ten different organisations, including several top notch universities. The group spent over three years experimenting with the technique of Flash Lamp Annealing (FLA), which enables rapid heating and cooling in a timeframe of milliseconds. Their work, which culminated in the definition of the FLASiC process, was made possible by the development and use of an extensive computer model. The model solves the equations describing the thermal processes occurring during FLA, such as the flow of heat, the resulting temperature distribution and the critical process of melting. The thermal model is supplemented by an optical model that performs the energy calculations in the substrate layers. The model proved very helpful in optimising the melt stop technique. This reduces the risk of uneven surfaces that lower final product quality and, in the worst case, render the wafer useless. The inclusion of a carbon model led to further improvements. The final component of the modelling system is a module that computes the stress felt by the wafers when subjected to FLA. Overall, the model results compare very well to what the consortium observed in the semiconductor laboratory. The Cambridge University scientists would also like to point out that the modelling system has potential to be applied in other disciplines.