Simultaneous measurement of fine pattern shape and overall shape by a nano-profiler

Abstract

Improving the optical performance and functions of mirrors and lenses requires manufacturing pattern shapes such as those of microlens arrays. In this context, various measuring devices have been developed to accurately measure the depth of shapes with a microscopic interferometer. However, with an interferometer, the number of pixels of a light-receiving element, such as a charge-coupled device, is limited; furthermore, when measuring a pattern shape, the measurement field of view becomes narrow. Thus, measuring a wide range of shapes is not possible. By contrast, if the device can arbitrarily increase the number of measurement points, such as in the case of a three-dimensional measuring machine, in principle, a pattern shape can be measured, while ensuring the measurement capability for a wide range of shapes; however, in this case, the measurement time increases. A nano-profiler previously developed by the authors can measure the shape and slope angle distribution of a surface with a laser beam. In this study, the measurement program was changed to realize continuous high-speed scanning at 1 kHz, and the number of measurement points was increased to verify the compatibility between fine pattern shape measurements and diverse shape measurements. The results measured by the nano-profiler were compared with those obtained using microscopic and Fizeau-type interferometers, which can measure the pattern and overall shapes, respectively. In comparison, the difference in pattern depth and overall shape was 2.1 and 2.9 nm PV, respectively.