Comparison of image shortening effects in x-ray and optical lithography

Abstract

Data on image shortening effects with patterns replicated with x-ray and optical lithography are presented. The x-ray exposures were performed at the IBM Advanced Lithography Facility using the Helios superconducting storage ring and a SUSS stepper. The optical exposures were performed using SVGL Micrascan 1 and 2 tools and biased optical masks. The results indicate that the image shortening effects using x-ray lithography (XRL) are considerably less pronounced than the effects observed with the optical tools. In addition, modeling of the image shortening effects for XRL using the xmas three-dimensional program for resist patterns is presented and compared with experimental results.

Characterization of pattern geometrical effect on line end shortening in x-ray lithography

“…Such a result is consistent with previous experimental results. [9][10][11] Also, line end shortening was affected by the position of the neighboring pattern. Several different spacings from Dϭ0.3 L -4.5 L were applied to examine their effects on line end shortening.…”

“…Several previous studies have reported that the low contrast x-ray mask was better for the fine line x-ray lithography 14,15 and reducing the image a͒ Electronic mail: msyi@palc.postech.ac.kr shortening. 11,12 The Au patterns having feature sizes from Lϭ0.1 to 0.3 m were delineated on 1.0 m thick SiN membranes. The x-ray exposures were performed in the Postech Advanced Lithography Center ͑PALC͒ using the Pohang Accelerator Laboratory ͑PAL͒ synchrotron storage ring 16 and a x-ray stepper, Satellite 800, developed at Sumitomo Heavy Industry.…”

“…Line end shortening has been studied by several authors and the effects of the absorber thickness and the gap between mask and wafer have already been examined. [11][12][13] Also, reduction of line end shortening by modifying the mask pattern has been described. 13 In this article, we have characterized line end shortening in chemically amplified resists ͑CAR͒ from the viewpoint of mask pattern geometry using several kinds of test patterns.…”

Effect of absorber thickness on image shortening in x-ray lithography

“…In a previous article, 1 it was shown using simulations and experiment that image shortening effects in x-ray lithography were smaller than in optical lithography. The effect of mask absorber thickness on image shortening during x-ray lithography of typical SRAM and DRAM device patterns is addressed in this article.…”