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Proceedings Paper

Step And Repeat Wafer Imaging
Author(s): Jeanne Roussel
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Paper Abstract

Increased packing densities require smaller geometries. For memory circuits the trend is towards 2 microns and less. Available and suitable imaging techniques for wafer production are limited. Photolithographic step-and-repeat imaging at reduction ratios greater than one to one appears to be a most promising technique. Its successful application demands a clear understanding of wafer process parameters and system imaging interaction, appropriate expertise for integration of opto-mechanical - electronics and control functions, component selection, and design trade-offs. A major performance factor is the illumination system. This paper will provide a detailed description of illumination system criteria and implementation. A new illuminator, an extension of a proven design, makes possible exposure energy levels in excess of 300 milliwatts/cm2 of great uniformity over a 10 mm x 10 mm area. Resulting exposure times are fast enough to make direct stepping on the wafer practical. Images stepped on wafers in both negative and positive photoresists will be discussed. Data obtained by photo-optical and SEM means demonstrate the potential usefulness in terms of resolution, topology, resist thickness and type, of photolithographic direct wafer exposure. Standing wave effects and negative resists exposed without nitrogen purge will be discussed.

Paper Details

Date Published: 6 September 1978
PDF: 6 pages
Proc. SPIE 0135, Developments in Semiconductor Microlithography III, (6 September 1978); doi: 10.1117/12.956110
Show Author Affiliations
Jeanne Roussel, GCA/Burlington (United States)


Published in SPIE Proceedings Vol. 0135:
Developments in Semiconductor Microlithography III
Dino R. Ciarlo; James W. Dey; Ken Hoeppner, Editor(s)

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