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18 December 1998 Resolution limits with 248-nm strong phase-shifting techniques for contact patterning applications
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As conventional lithography capability is reaching the limit, resolution enhancement becomes a crucial element to extend the lithography capability. The main purpose of this paper is to examine the capabilities and limitations of various phase shifting techniques. Using contact applications as an example, alternating and phase edge phase shifter were evaluated with single and double exposure techniques. Detailed discussion will include both simulation and experimental results. The PSM performances were predicted with Intel in-house simulator. Analysis was done based on aerial image formation using peak intensity and Modulation Transfer Function to evaluate resolution capabilities. For each type of phase shifter, good resolution enhancement was achieved with optimized pitch range of dense structures. Experimental results of focus-exposure matrices were taken on a DUV stepper with NA of 0.42. Significant resolution enhancement was demonstrated with k1 as low as 0.32 which is far below the limitation a k1 equals 0.5. Small contacts with tight pitch, i.e. 180 nm contact with 380 nm pitch, were demonstrated with reasonable depth of focus by using double exposure technique. By using single exposure alternating phase shifting technique pitches down to 460 nm is steadily resolved. With conventional mask, 350 nm contacts with 700 nm pitch is reported as the minimum printable range for the same stepper.
© (1998) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Yulia O. Korobko, Mei-Chien Lu, Jesmar Telans, and Jeffrey E. Powers "Resolution limits with 248-nm strong phase-shifting techniques for contact patterning applications", Proc. SPIE 3546, 18th Annual BACUS Symposium on Photomask Technology and Management, (18 December 1998);

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