5 July 2000 Precise CD control of 140-nm gate patterns using phase-edge PSM
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We investigated the critical dimension (CD) accuracy of 140- nm gate patterns fabricated by using the KrF phase-edge phase shifting mask (PSM), especially the dependence of the CD variation on the pattern pitch conditions, phase assignment conditions, and process conditions such as defocus and misalignment. We found that the phase assignment conditions for the neighboring 0 and 180 degree aperture pairs affected the gate width by 10 nm. The phase of apertures in the PSM should be assigned by taking the phase assignment condition of the neighboring aperture pairs into account when these aperture pairs are placed within the distance of 0.5 micrometers . The CD variation due to defocusing was found to be minimized when the Cr width of fine gate patterns in the PSM was set at 100 nm. The CD variation caused by misalignment between the PSM and the trim mask was also examined, and the trim mask generated by merging the shifter layer gave the minimum CD variation in relation to misalignment. In addition, the CD variation along the length of a fine gate pattern was examined, and the necking shape near the corners of apertures was pointed out. An additional pattern feature was evaluated to avoid it.
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Shoji Hotta, Shoji Hotta, Osamu Inoue, Osamu Inoue, Hiroshi Fukuda, Hiroshi Fukuda, Norio Hasegawa, Norio Hasegawa, } "Precise CD control of 140-nm gate patterns using phase-edge PSM", Proc. SPIE 4000, Optical Microlithography XIII, (5 July 2000); doi: 10.1117/12.388973; https://doi.org/10.1117/12.388973


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