Etching of photosensitive chalcogenide glasses:experiments and simulations

We have developed a three-dimensional simulation algorithm based on fast marching method that mimics the etching behavior of chalcogenide photoresists, especially for maskless interference lithography. This lithography exposure is characterized by continuous variation of the exposure intensity inside the photoresist, without step like variation. Furthermore, the chalcogenide photoresist has a "gray-scale" behavior, without definite threshold. The resulting etching process is very sensitive to exposure dose and etching time. The optimal relations between these parameters are determined both theoretically and experimentally. A very good agreement between calculation and experimental results is shown, opening the door to complex nanostructures engineering.