Two-beam-current method for e-beam writing gray-scale masks and its application to high-resolution microstructures.
A two-beam-current method is introduced for e-beam writing in the fabrication of gray-scale masks. Compared with the simpler single-current method, the two-beam-current method offers two important advantages: (a) it can achieve a much larger dynamic range for e-beam exposure; (b) the writing time for a gray-scale mask can be reduced when a large pattern is to be written. Here, the new method is first described in detail and its application to the fabrication of our new gray-scale mask is demonstrated. Then, the improved gray-scale masks were employed to fabricate large dynamic range, high-resolution micro-optical elements of less than a couple of micrometers depth, using deep ultraviolet lithography at 248 nm wavelength and an inductively coupled plasma reactive ion etching system.
1Department of Electrical and Computer Engineering, University of California at San Diego, 9500 Gilman Drive, La Jolla, California 92093-0407, USA. joe@triagewireless.com
Zhou
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Zhou
Sing H
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Lee