Characterization of a process development tool for ion projection lithography

This article describes the performance of a process development tool for ion projection lithography (IPL), realized as part of the MEDEA program of the European Union. This system was designed for a 12.5 X 12.5 mm(2) exposure field and 4:1 reduction ratio between the mask and the wafer. The design incorporates several novel concepts, including a negative electrostatic lens at the mask to reduce distortion and field-composable lenses to provide electronic fine alignment of the system. Continuous control of magnification, position offset, distortion, and telecentricity is provided by a real-time feedback system (pattern lock) that monitors the position of reference beamlets traveling in parallel with the integrated circuit image through the ion-optical system. After mechanically aligning the center and tilt of the lenses relative to the optical axis to within 10 mum and 50 murad, respectively, we achieved 100 nm resolution over the full design field, with 75 nm resolution in local areas within the field. The reduction ratio was within 0.01% of design predictions. We also discuss the experimental plan for further demonstrating the efficacy of IPL for integrated circuit manufacturing far below 100 nm design rules. (C) 2001 American Vacuum Society.