28 April 1999 Best focus shift issues from focusing system of ASML PAS-5000/50 steppers
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Proceedings Volume 3741, Lithography for Semiconductor Manufacturing; (1999); doi: 10.1117/12.346893
Event: Microelectronic Manufacturing Technologies, 1999, Edinburgh, United Kingdom
Abstract
The best focus shift problem was observed on PAS-5000/50 I- line system. The best focus shift could induce poor resist profile in back-end lithography exposure processes, and caused blind via-holes or damage on conductor lines after plasma etch. The effects of topography change, pattern layout and focus laser spot position on the best focus determination were proved related to the focusing system design, single point focus detection with small size probe beam. of PAS-5000/50 steppers. In the main paper, the weak points of the design are pointed out, i.e. the unwanted information due to its dependence on step topography and layout may be collected and cause defocused resist profile during focusing. Though the application of dark-tone digitized scribe line design on dielectric layers reduces step topography discrepancy between main cell and scribe line and partially solves the problems; however, the complete solutions rely on the fundamental improvements on the stepper focusing algorithm.
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Ming-Huei Tseng, Feng-Liang Lai, Li-Kong Turn, "Best focus shift issues from focusing system of ASML PAS-5000/50 steppers", Proc. SPIE 3741, Lithography for Semiconductor Manufacturing, (28 April 1999); doi: 10.1117/12.346893; https://doi.org/10.1117/12.346893
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KEYWORDS
Semiconducting wafers

Dielectrics

Lithography

Photoresist processing

Plasma etching

Sensors

Etching

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