Correlated Surface Roughening During Photoresist Development

BACKGROUND: Previous simulation work has shown that uncorrelated Gaussian randomness in the development rate produces surface roughness in a resist that obeys Family-Viscek scaling in the KPZ universality class. However, more rigorous mesoscale simulations produce anomalous scaling. METHODS: Using a stochastic resist simulator, the dynamical roughness behavior of resist development in 2D is studied with various amounts of correlation in the underlying development rate randomness. RESULTS: For length scales greater than about 5 xi (the correlation length of the underlying randomness), the dynamical roughness behavior obeys standard Family-Viscek scaling within the KPZ universality class. For length scales on the order of a few xi or less, the mixed correlations of both xi and xi(vertical bar vertical bar) make the results anomalous. CONCLUSIONS: It appears that correlations can explain at least some of the anomalous scaling behavior observed previously through the use of mesoscale simulations. Simple scaling relationship can still apply, however, over appropriate length scales.