Scatterometry for optimization of injection molded nanostructures at the fabrication line

A compact scatterometer has been build and tested at a production facility. The scatterometer is used to characterize the feature dimensions of injection molded polymer nanostructures and give on-site direct feedback to the operator on the produced quality. In this way, the injection molding process parameters are iteratively improved until accurate replication of the nanostructures has been achieved. The tests are carried out on 2-in. diameter samples with nearly 100 nanostructured areas, consisting of diffractive line gratings with different periods and orientations. It is found that different nanostructures require different process parameters to reach high replication fidelity. Scatterometry measurements are very fast, and will therefore not present a bottleneck when used for quality assurance during production. We furthermore examine the spatial variations in the replicated structures within molded polymer discs using an imaging scatterometer. We demonstrate that the imaging scatterometer is capable of characterizing the entire sample simultaneously, in contrast to the compact scatterometer which performs a local analysis based on measurements on the individual grating regions.