Deconstructing contact hole CD printing variability in EUV lithography

Abstract

Lithographic CD printing variability can be easily captured with a CDU measurement, however delineating the most significant sources causing the variability is challenging. In EUV lithography, the resist, reticle, metrology methodology, and stochastics are examples of factors that influence printing variability. Determining the most significant sources of variability in contact hole and via patterning is particularly interesting because the variability can be measured as a function of two tethered dimensions. Contact hole (CH) variability has a direct impact on device performance while via variability affects metal area scaling and design. By studying sources of variability opportunities for improving device performance and scaling can be identified. In this paper, we will examine sources of contact patterning variability in EUV lithography comprehensively using various EUV exposure tools as well as simulation methods. We will present a benchmark of current state of the art materials and patterning methods with the goal of assessing contact hole printability at the limit of 0.33 NA EUV lithography.