A multiple-electron-beam exposure system for high-throughput, direct-write submicrometer lithography

Scanning-electron-beam lithography has not been generally accepted for the direct writing of patterns on wafers, primarily because of the time required for a single beam to scan a production-sized wafer (100 to 150 mm in diameter). This paper reports progress on a scheme for multiple-beam lithography using an immersion screen lens to overcome the time problem. In this approach, each die of the wafer has its own writing beam. All the beams are scanned and blanked in parallel so that identical patterns are written simultaneously over all dice. A laser interferometer stage under computer control enables dice of large area to be completely covered, despite limitations on the deflection amplitude of the beamlets. It is shown that a 1-min cycle time is practical using PBS resist. Preliminary results from an experimental machine based on these principles are given.