Design of a low-brightness highly uniform source for projection electron-beam lithography (SCALPEL)

Warren K. Waskiewicz; James Alexander Liddle

doi:10.1117/12.287808

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25 September 1997 Design of a low-brightness highly uniform source for projection electron-beam lithography (SCALPEL)

Warren K. Waskiewicz, James Alexander Liddle

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Proceedings Volume 3155, Charged Particle Optics III; (1997) https://doi.org/10.1117/12.287808
Event: Optical Science, Engineering and Instrumentation '97, 1997, San Diego, CA, United States

Abstract

The requirements for a projection electron-beam lithography source, such as one suitable for a system based upon the SCAL- PEL^R (scattering with angular limitation projection electron-beam lithography) technique, are significantly different from those of a conventional TEM, SEM, or direct write type of instrument. While high resolution imaging is still a primary goal, this must now be achieved at relatively high (1-200 (mu) A) beam currents in order to realize economically meaningful wafer throughput. Space-charge limitations considered over the entire system (not just the electron gun) lead to the use of relatively large illumination angles (approximately 0.5 mrad). Taken together with an illuminated mask area of approximately 1 mm², this means that the electron gun axial brightness needs to be only 10² to 10⁴ Acm^-2sr^-1, as compared with a value of 10⁶ to 10⁹ Acm^-2sr^-1 for a TEM. Similar considerations indicate that the source emittance must exceed 700 micrometer(DOT)mrad, which is more than an order of magnitude larger than that provided for a standard focused-beam system. Additionally, the uniformity of the illumination must be within 2% in order to ensure that the variation in printed feature size across the imaged area remains negligible. This type of source performance must be stable for extended periods of time in order to maximize the uptime of the lithography tool. In this paper we review the source built for our SCALPEL proof-of-concept system, discuss the impact of an interim modification, and then examine the potential of a further source redesign.

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Warren K. Waskiewicz and James Alexander Liddle "Design of a low-brightness highly uniform source for projection electron-beam lithography (SCALPEL)", Proc. SPIE 3155, Charged Particle Optics III, (25 September 1997); https://doi.org/10.1117/12.287808

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