High-resolution x-ray masks for high-aspect-ratio microelectromechanical systems (HARMS)

Lin Wang; Flavio Aristone; Jost Goettert; Jong Ren Kong; Keith Bradshaw; Todd R. Christenson; Yohannes M. Desta; Yoonyoung Jin

doi:10.1117/12.478268

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15 January 2003 High resolution x-ray masks for high aspect ratio microelectromechanical systems (HARMS)

Lin Wang, Flavio Aristone, Jost Goettert, Jong Ren Kong, Keith Bradshaw, Todd R. Christenson, Yohannes M. Desta, Yoonyoung Jin

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Proceedings Volume 4979, Micromachining and Microfabrication Process Technology VIII; (2003) https://doi.org/10.1117/12.478268
Event: Micromachining and Microfabrication, 2003, San Jose, CA, United States

Abstract

X-ray lithography is commonly used to build high aspect ratio microstructures (HARMS) in a 1:1 proximity printing process. HARMS fabrication requires high energy X-rays to pattern thick resist layers; therefore the absorber thickness of the working X-ray mask needs to be 10-50 μm in order to provide high contrast. To realize high resolution working X ray masks, it is necessary to use intermediate X-ray masks which have been fabricated using e beam or laser lithographic techniques. The intermediate masks are characterized by submicron resolution critical dimensions (CD) but comparatively lower structural heights (~2 μm). This paper mainly focuses on the fabrication of high resolution X-ray intermediate masks. A three-step approach is used to build the high resolution X-ray masks. First, a so called initial mask with sub-micron absorber thickness is fabricated on a 1 μm thick silicon nitride membrane using a 50KeV e beam writer and gold electroplating. The initial X-ray mask has a gold thickness of 0.56 μm and a maximum aspect ratio of 4:1. Soft X-ray lithography and gold electroplating processes are used to copy the initial mask to form an intermediate mask with 1 μm of gold. The intermediate mask can be used to fabricate a working X-ray mask by following a similar set of procedures outlined above.

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Lin Wang, Flavio Aristone, Jost Goettert, Jong Ren Kong, Keith Bradshaw, Todd R. Christenson, Yohannes M. Desta, and Yoonyoung Jin "High resolution x-ray masks for high aspect ratio microelectromechanical systems (HARMS)", Proc. SPIE 4979, Micromachining and Microfabrication Process Technology VIII, (15 January 2003); https://doi.org/10.1117/12.478268

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