Multidimensional Process Optimization of a negative E-Beam Photoresist for Silicon-Waveguide Manufacturing

摘要

In this study, a high-resolution chemically amplified negative photoresist for electron-beam writing was successfully run in and optimized for photonic device manufacturing. The investigation of the photoresist contrast enabled the determination of bake parameter influences. This provided the basis for process optimization by critical dimension measurements. Therefore, two different procedures were approached: a parameter-wise and a multidimensional optimization. The parameter-wise approach investigated the influence of each lithography bake parameter for a certain set of exposure doses iteratively, by a bossung-plot like procedure. Every parameter was investigated once and in descending magnitude of process influence, to maximize the optimization impact by a low usage of resources. For the verification of the iterative approach, a multidimensional process-response-model was set up. The model enabled the simulation of the lithography process behavior, while taking the bake and exposure interdependencies into account. This allowed the identification of optimized processing parameters, which enabled the production of smooth and critical dimension stable lines in photoresist.