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Optical Engineering

The Way To One-Half Micrometer Photolithography
Author(s): Masaomi Kameyama; Kazuo Ushida
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Paper Abstract

To investigate the way to achieve 0.5 µm photolithography, experiments have been performed with a high-numerical-aperture lens, with multilayer and contrast-enhancement-layer resist processes, and with an excimer laser deep-UV stepper. The 0.6 N.A. lens is for the g-line and has a 5 mm x 5 mm field size. Single-layer resist exposures show good profiles at 0.6 µm line/space (L/S), with no effects from highly oblique illumination, and a depth of focus of 1.25 µm. Multilayer resists using spin-on-glass and contrast-enhancement layers improve the resolution to 0.375 µm with a large N.A. lens and to 0.5 µm with an i-line lens of N.A. = 0.35. Because the large numerical aperture alone cannot reach 0.5 µm and because a large field, large N.A. lens is difficult to manufacture, an i-line lens with moderate N.A. and large field appears to be a better approach. As a more advanced experiment, a KrF excimer laser stepper with an achromatic quartz/fluorite lens of N.A. = 0.37 shows no effect of speckle and has produced a 0.35 µm L/S in PMMA for a k of 0.5. The resolution with MP2400 photoresist is only 0.4 µm because of deep-UV absorption. This shows the need for more work on practical deep-UV photoresists.

Paper Details

Date Published: 1 April 1987
PDF: 7 pages
Opt. Eng. 26(4) doi: 10.1117/12.7974071
Published in: Optical Engineering Volume 26, Issue 4
Show Author Affiliations
Masaomi Kameyama, Nippon Kogaku K. K. (Nikon) (Japan)
Kazuo Ushida, Nippon Kociaku K. K. (Nikon) (Japan)


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