Simulation of microcrack effects in dissolution of positive resist exposed by X-ray lithography

Etchant percolation through voids plays an important role in dissolution of radiation sensitive materials in IC manufacture, but analysis and simulation of this phenomenon are hampered by the complexity of carrying out simulations at up to 20000 voids etching simultaneously. An attempt is made to use a simplified material crack model and a formulation of the model in terms of cellular automata, which is well suited for massively parallel computation. Simulation is then used to characterize etch front propagation and the resulting resist profile shape. An analytic model predicting that the etch front velocity goes as a geometrical series in the product of crack density times the square of crack length shows agreement with the simulation results.>