Aerial image analysis of quarter-micrometer patterns on a 0.5-NA excimer ste

摘要

Abstract: Applying a method for direct on stepper measurement of aerial images, the quarter micron performance of an advanced deep UV excimer stepper is analyzed. The aerial images are compared to corresponding simulation results as well as data obtained on an aerial image measurement system (AIMS). The study includes three different mask types: standard chrome on glass, an attenuated and an alternating phase shifting mask. Substrate effects as well as laser spectral purity effects have been measured. In general, the data show that simulation and AIMS data represent an upper limit for the aerial image contrast, which may be degraded significantly under real world imaging conditions. Use of a bottom anti reflective layer and a new laser with improved spectral bandwidth result in optimum aerial images close to those measured on AIMS, but they are still worse than simulation results. Some examples of quarter micron resist profiles and process windows in a deep UV resist are shown that were obtained under these optimized conditions with an excimer laser stepper. !4