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Stitching Error Analysis in an Electron Beam Lithography System: Column Vibration Effect

The column vibration effects on field stitching accuracy in an electron beam lithography system are investigated. Field stitching error analysis shows that beam placement error caused by column vibration is about 0.04 µm. This corresponds to 80% of the required accuracy for 0.3-µm ULSIs. In this study, the relation between column vibration and field stitching accuracy is clarified using modal analyses by measurement of column acceleration and by computer simulation. Based on these analyses, a new anti-vibration system was designed. As a result, stitching error due to column vibration is reduced to less than 0.01 µm, and field stitching accuracy of 0.05 µm (|Mean|+3σ) is achieved. In the next-generation, quantitative understanding of disturbance effects such as vibration will be the most critical issue in designing more accurate electron beam lithography systems.