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Proceedings Paper

Base-line error-free non-TTL alignment system using oblique illumination for wafer steppers
Author(s): Dohoon Kim; Kag Hyeon Lee; Yong-Ho Oh; Jong-Hyun Lee; Hai Bin Chung; Hyung Joun Yoo
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Paper Abstract

In this paper, an alignment method with oblique illumination and oblique detection named ZBAS (Zero Base-line Alignment System) is proposed and its characteristics and applications are analyzed. It detects the position error from alignment mark at the exposure position even though it is a non-TTL method. The alignment mark, a diffraction pattern with a 4 micrometers width (8 micrometers pitch), is illuminated with a He-Ne laser beam at an incident angle of 75 degree(s) and the first order diffracted beam at this is detected as an alignment signal at a diffraction angle of 60 degree(s). The peak value of the alignment signal with appropriate electrical system is about 20 mV and the signal sensitivity to the wafer position is 0.5 mV/0.1 micrometers . The theoretical analysis of ZBAS was carried out with respect to the effects of pattern depth and resist thickness. The result shows the stable detection is realized by a 2- wavelength (670,780 nm) illumination, in which the variation of the calculated signal is 27% in the range of 0.6 approximately equals 1.2 micrometers of pattern depth, 37% in the range of 0.6 approximately equals 1.2 micrometers of resist thickness. In conclusion, the ZBAS was verified as a potential alignment system in excimer laser stepper, which has a smaller base-line error than the conventional non-TTL method.

Paper Details

Date Published: 26 May 1995
PDF: 10 pages
Proc. SPIE 2440, Optical/Laser Microlithography VIII, (26 May 1995); doi: 10.1117/12.209318
Show Author Affiliations
Dohoon Kim, Electronics & Telecommunications Research Institute (South Korea)
Kag Hyeon Lee, Electronics & Telecommunications Research Institute (South Korea)
Yong-Ho Oh, Electronics & Telecommunications Research Institute (South Korea)
Jong-Hyun Lee, Electronics & Telecommunications Research Institute (South Korea)
Hai Bin Chung, Electronics & Telecommunications Research Institute (South Korea)
Hyung Joun Yoo, Electronics & Telecommunications Research Institute (South Korea)


Published in SPIE Proceedings Vol. 2440:
Optical/Laser Microlithography VIII
Timothy A. Brunner, Editor(s)

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