Paper
27 March 2007 ACLV performance dry vs. immersion on 45-nm ground rules
Uwe P. Schroeder, Chin-Chin Yap, Chandra S. Sarma, Alan Thomas
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Abstract
In this paper we have analyzed the ACLV performance of a 45nm CMOS logic process as a function of gate layer exposure tool. Data from identical masks and with identical litho processes is compared side by side on immersion and dry lithography. Theoretically, the improved focus control of immersion scanners allows tighter CD control for pitches that have lower process windows. Thereby, the ACLV performance of immersion lithography is expected to be better than on a comparable dry tool, when keeping all other parameters the same. This is specifically important for foundry processes where pitches are not restricted. The wafer results give somewhat ambivalent answers. Overall, ACLV performance of the dry tool is very similar to the immersion tool. Taking out systematic contributions, it becomes evident that the ACLV is dominated by dose effects and less by the curvature of the Bossung plots. Even though the focus window is considerably smaller on the dry tool, the apparently better dose control leads to better ACLV performance after subtracting systematic effects.
© (2007) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Uwe P. Schroeder, Chin-Chin Yap, Chandra S. Sarma, and Alan Thomas "ACLV performance dry vs. immersion on 45-nm ground rules", Proc. SPIE 6520, Optical Microlithography XX, 65204I (27 March 2007); https://doi.org/10.1117/12.713113
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KEYWORDS
Photomasks

Semiconducting wafers

Critical dimension metrology

Lithography

Scanning electron microscopy

Metrology

Semiconductors

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