EL-4, a new generation electron-beam lithography system

The new generation electron-beam lithography system EL-4 is described, designed for direct wafer exposure as well as optical reticle and x-ray mask making. The new architecture features control through workstations and local area network communication between these and the microprocessor-controlled subsystems. The system has on-line error checking and diagnostics. Wafers up to 200 mm diam are handled individually with a Standard Mechanical InterFace-compatible, fully robotic system, and are electrostatically chucked to the stage. Reticles are clamped to the stage with double-sided e/s chucks, ring-bonded membrane masks are kinematically held in a carrier chucked to the stage. The reticle/mask maker has an internal temperature control system in addition to the clean-room climate control for the entire mechanical hardware. The electron optics accommodate triangle as well as rectangle spot formation, and for direct write application a throughput-enhancing third level in the deflection hierarchy. High resolution variable-axis immersion lens optics are used for beam projection and positioning on the target. The column design is significantly advanced over EL-3 for improved integrity and performance as well as automated control through electronics with menu-driven touch screen for user-friendly operation. The first EL-4 system is currently in qualification as a reticle/mask maker for 0.25 μm device technology.