Lawrence Berkeley National Laboratory

Background: As target feature sizes for EUV lithography shrink, it is becoming ever more important to understand the intricate details of photoresist materials, including the role of the "third dimension"- the dimension perpendicular to the wafer. With resist thicknesses shrinking toward the single-digit nanometer scale alongside target linewidths, small changes in resist performance in this dimension will have a greater overall effect on pattern quality. Aim: To use modeling to understand the effect that the third dimension has on resist performance, in particular the interplay between the third dimension and resist stochastics. Approach: We developed a three-dimensional version of the multivariate Poisson propagation model, a stochastic resist simulator. As a test case for the model, we explore the role of acid diffusion in the so-called third dimension by simulating 105 vias at a series of z-blur conditions. Results: Our model suggests that increased z-blur yields an improvement in both dose to size and pattern uniformity without sacrificing resolution. Conclusions: We have developed a 3D resist model that can simulate large numbers of contacts. Early results from the 3D model show improved patterning performance can be achieved by increasing the z-blur.