Modelling and compensation of thermally induced positioning errors in a high precision positioning application

Abstract

Thermal scanning probe lithography (t-SPL) is a promising technology to create patterns at the nanometre scale. So far, a commercially available t-SPL tool only exists for small, centimetre scale work pieces typically used in the university research environment. Scaling this technology to work with industry standard wafers requires much larger mechanical positioning units. These are subject to thermally induced deformations and consequently positioning errors. This work suggests a model based compensation of a mechanical positioning unit in combination with a direct position measurement enabled by the t-SPL patterning tool. Based on a linear model of the positioning unit, a Kalman based filter is designed, to estimate thermal errors during the patterning process and use position measurements between patterning phases for re-calibration. The presented filter does not require additional measurement equipment for the compensation. An application of the presented algorithm on an experimental set-up shows a significant reduction of thermally induced position errors.