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Journal of Micro/Nanolithography, MEMS, and MOEMS

Critical dimension control using ultrashort laser for improving wafer critical dimension uniformity
Author(s): Dan Avizemer; Ofir Sharoni; Sergey Oshemkov; Avi Cohen; Asaf Dayan; Ranjan Khurana; Dave Kewley
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Paper 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) [<italic<Proc. SPIE</italic<<bold<6152</bold<, 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 <italic<in-situ</italic< 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.

Paper Details

Date Published: 11 September 2015
PDF: 7 pages
J. Micro/Nanolith. 14(3) 033510 doi: 10.1117/1.JMM.14.3.033510
Published in: Journal of Micro/Nanolithography, MEMS, and MOEMS Volume 14, Issue 3
Show Author Affiliations
Dan Avizemer, Carl Zeiss SMS Ltd. (Israel)
Ofir Sharoni, Carl Zeiss SMS Ltd. (Israel)
Sergey Oshemkov, Carl Zeiss SMS Ltd. (Israel)
Avi Cohen, Carl Zeiss SMS Ltd. (Israel)
Asaf Dayan, Carl Zeiss SBE, LLC (United States)
Ranjan Khurana, Micron Technology, Inc. (United States)
Dave Kewley, Micron Technology, Inc. (United States)

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