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Articles you may be interested inInfluence of a high vacuum on the precise positioning using an ultrasonic linear motor Rev. Sci. Instrum. 82, 015112 (2011);A new XY stage employing ultrasonic linear motors that is simple, compact, and completely nonmagnetic was developed for an e-beam x-ray mask writer employing step-and-repeat writing. The main performance results are: ͑1͒ position fluctuations during writing are less than Ϯ4 nm; ͑2͒ the time for a 650 m step movement is less than 270 ms; ͑3͒ the magnetic interference is less than Ϯ1 nT at the e-beam deflection center; and ͑4͒ the vibration of the stage when moving at a constant speed is less than Ϯ0.25 m/s 2 . The new stage is also very easy to maintain. It has been installed in the EB-X3 e-beam x-ray mask writer.

XY stage driven by ultrasonic linear motors for the electron-beam x-ray mask writer EB-X3 J.The EB-X3 is an electron-beam mask writer designed to pattern x-ray masks with minimum feature sizes of 100 nm and below with good beam placement accuracy. The target patterning resolution is 50 nm, and a beam acceleration voltage of 100 kV is used to achieve it. This resolution has already been demonstrated using the previous version of the writer, the EB-X2 ͑developed last year͒, which also employs an acceleration voltage of 100 kV. On the other hand, the target placement accuracy for the EB-X3 is less than 10 nm, which is more than three times smaller than that for the EB-X2. To improve the placement accuracy, the resolution of the laser measurement system was changed from /128 ͑ϭ5 nm͒ to /1024 ͑ϭ0.6 nm͒, and the address unit was set to 1 nm, which yields a reproducibility of mark detection of 4 nm ͑3͒ and a calibration accuracy for deflection distortion of 5 nm͉͑mean͉ϩ3͒. In addition, the laser measurement system monitors five axes ͑X, Y, yaw, and pitch ͓X,Y͔͒ and the results are fed back to position the beam. Furthermore, the signal fluctuations of the deflection, lens, and aligner circuits were reduced, so that beam fluctuations are kept under 2 nm. The EB-X3 was delivered to the ASET Super-fine SR Lithography Laboratory in March 1999, and is now being evaluated for use in x-ray mask fabrication. The prospects are good for achievement of a placement accuracy of 10 nm ͑3͒ in the near future.

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