Lithography

Critical dimension control using ultrashort laser for improving wafer critical dimension uniformity

[+] Author Affiliations
Dan Avizemer, Ofir Sharoni, Sergey Oshemkov, Avi Cohen

Carl Zeiss SMS Ltd., 44 Maale Camon, Karmiel 21613, Israel

Asaf Dayan

Carl Zeiss SBE, LLC, SMS Division, One Corporation Way, Peabody, Massachusetts 01960, United States

Ranjan Khurana, Dave Kewley

Micron Technology, Inc., 8000 South Federal Way, Boise, Idaho 83707, United States

J. Micro/Nanolith. MEMS MOEMS. 14(3), 033510 (Sep 11, 2015). doi:10.1117/1.JMM.14.3.033510
History: Received November 2, 2014; Accepted August 4, 2015
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Abstract.  Requirements for control of critical dimension (CD) become more demanding as the integrated circuit (IC) feature size specifications become tighter and tighter. Critical dimension control, also known as CDC, is a well-known laser-based process in the IC industry that has proven to be robust, repeatable, and efficient in adjusting wafer CD uniformity (CDU) [Proc. SPIE6152, 615225 (2006)]. The process involves locally and selectively attenuating the deep ultraviolet light which goes through the photomask to the wafer. The input data for the CDC process in the wafer fab is typically taken from wafer CDU data, which is measured by metrology tools such as wafer-critical dimension—scanning electron microscopy (CD-SEM), wafer optical scatterometry, or wafer level CD (WLCD). The CD correction process uses the CDU data in order to create an attenuation correction contour, which is later applied by the in-situ ultrashort laser system of the CDC to locally change the transmission of the photomask. The ultrashort pulsed laser system creates small, partially scattered, Shade-In-Elements (also known as pixels) by focusing the laser beam inside the quartz bulk of the photomask. This results in the formation of a localized, intravolume, quartz modified area, which has a different refractive index than the quartz bulk itself. The CDC process flow for improving wafer CDU in a wafer fab with detailed explanations of the shading elements formation inside the quartz by the ultrashort pulsed laser is reviewed.

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© 2015 Society of Photo-Optical Instrumentation Engineers

Citation

Dan Avizemer ; Ofir Sharoni ; Sergey Oshemkov ; Avi Cohen ; Asaf Dayan, et al.
"Critical dimension control using ultrashort laser for improving wafer critical dimension uniformity", J. Micro/Nanolith. MEMS MOEMS. 14(3), 033510 (Sep 11, 2015). ; http://dx.doi.org/10.1117/1.JMM.14.3.033510


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