Electron beam appts. adjustment system for semiconductor processing - sequentially forms images of beam cross=section in target plane and entrance pupil

摘要

The adjustment system, for the electron beam is used in lithography in producing microelectronic circuits, has preliminary pupil adjustment performed by imaging the aperture stop and focussing the pupil in the plane of the stop. Format adjustment is accomplished by imaging the target plane and proceeding in steps, correcting each error separately. Final pupil adjustment is achieved by imaging the aperture and changing format cyclically. The target plane is then again imaged and format calibration performed.