Process physics determining 2-D impurity profiles in VLSI devices

Physically robust diffusion models are required to simulate two-dimensional (2D) impurity profiles in VLSI devices. The accuracy of the initial dopant profiles severely limits the predictive capability of 2D device simulators. Historically, the most successful diffusion models have been based on point defect mechanisms involving either vacancy or in terstitial assisted diffusion. It is clear that the local con centration of defects determines the local diffusion coeffi cient, so the ability to model the point defect kinetics is essential for obtaining accurate 2D dopant profiles. We de scribe a series of kinetics experiments using 2D process test structures, which, when coupled with a 2D diffusion solver enable quantitative values for the generation, diffusion and surface recombination kinetics of the point defects to be obtained. The physical insight this work provides forms the basis of the diffusion models in the new 2D process simulator SUPREM-IV [1].