The formation and dissolution of Silicon self-interstitial clusters is linked to the phenomenon of TED (transient enhanced diffusion) which in turn has gained importance in the manufacturing of semiconductor devices. Based on theoretical considerations and measurements of the number of self-interstitial clusters during a thermal step we were interested in finding a suitable model for the formation and dissolution of self-interstitial clusters and extracting corresponding model parameters for two different technologies (i.e., material parameter sets). In order to automate the inverse modeling part a general optimization framework was used. Additional to solving this problem the same setup can solve a wide range of inverse modeling problems occurring in the domain of process simulation. Finally the results are discussed and compared with a previous model.