17 May 1994 Quarter-micrometer i-line lithography using an alternating phase-shift mask
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Phase-shifting mask allows remarkable improvement of the resolution and depth of focus than is possible with conventional mask. In this paper, we examine the optimum coherence factor ((sigma) ) and numerical aperture (NA) by considering the process margins of conventional and alternating shifter L&S patterns on high NA i-line stepper and next we investigate the possibility to apply this optimum parameter in real devices of 0.25 micrometers - 0.35 micrometers design rules. We evaluate the process window, line and space duty ratio, CD difference by proximity effect, illumination uniformity, and neighboring linewidth variation with experimental and simulations including resist profile as well as aerial image. In this experiment, we obtained the DOF of 2.0 micrometers for 0.25 micrometers alternating shifter L&S with an optimum coherence factor on high NA i-line stepper and we can conclude that 256 Mb DRAM with 0.25 micrometers design rule could be printed with large DOF.
© (1994) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Hung-Eil Kim, Hung-Eil Kim, YoungSik Kim, YoungSik Kim, Chul-Seung Lee, Chul-Seung Lee, Young-Mog Ham, Young-Mog Ham, Dong-Jun Ahn, Dong-Jun Ahn, Soo-Han Choi, Soo-Han Choi, } "Quarter-micrometer i-line lithography using an alternating phase-shift mask", Proc. SPIE 2197, Optical/Laser Microlithography VII, (17 May 1994); doi: 10.1117/12.175457; https://doi.org/10.1117/12.175457

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