STITCHING ERROR ANALYSIS IN AN ELECTRON-BEAM LITHOGRAPHY SYSTEM - COLUMN VIBRATION EFFECT

The column vibration effects on field stitching accuracy in an electro n beam lithography system are investigated. Field stitching error anal ysis shows that beam placement error caused by column vibration is abo ut 0.04 mum. This corresponds to 80% of the required accuracy for 0.3- mum ULSIs. In this study, the relation between column vibration and fi eld stitching accuracy is clarified using modal analyses by measuremen t of column acceleration and by computer simulation. Based on these an alyses, a new anti-vibration system was designed. As a result, stitchi ng error due to column vibration is reduced to less than 0.01 mum, and field stitching accuracy of 0.05 mum (\Mean\ +3sigma) is achieved. In the next-generation, quantitative understanding of disturbance effect s such as vibration will be the most critical issue in designing more accurate electron beam lithography systems.