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Double Exposure/Patterning Lithography. Hongki Kang. EE235 Mar 9 2009. NA (Numerical Aperture) For higher resolution, R ↓, λ ↓, n ↑, and α ↑. ArF source (193 nm). Resolution. <Trend of k 1 factor reduction since 2001 ,
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Double Exposure/Patterning Lithography Hongki Kang EE235 Mar 9 2009
NA (Numerical Aperture) • For higher resolution, R↓, λ↓, n↑, and α↑. • ArF source (193 nm) Resolution • <Trend of k1 factor reduction since 2001, • from Nanofabrication: Principles, Capabilities and Limits by Zheng Cui 2008>
ITRS 2007 Lithography 32 node Single Exposure - No solution yet Double Exposure - Solutions exist Lithography Challenge
What’s DE and DP? • <(a) single exposure, (b) double exposure, (c) double patterning • from Nanofabrication: Principles, Capabilities and Limits by Zheng Cui 2008>
Double Patterning Usinga Protective Crosslinking Layer < Process scheme of the examined double patterning method> • <A. Vanleenhove, D. Van Steenwinckel, "A litho-only approach to double patterning," Proc. of SPIE Vol. 6520, 65202F, 2007>
<SEM pictures of lines throughout the different process steps. 90 nm mask features on a 240 nm pitch, which gives 60 nm half pitch in double patterning (right SEM picture), with the NA of 0.75 which was used.> Double Patterning Usinga Protective Crosslinking Layer • <A. Vanleenhove, D. Van Steenwinckel, "A litho-only approach to double patterning," Proc. of SPIE Vol. 6520, 65202F, 2007>
~15 nm ~15 nm Double Patterning Usinga Protective Crosslinking Layer • <A. Vanleenhove, D. Van Steenwinckel, "A litho-only approach to double patterning," Proc. of SPIE Vol. 6520, 65202F, 2007>
As the temperature decreases, the crosslinking layer thickness decreases. • Trade off with the ability to protect the first patterned layer Double Patterning Usinga Protective Crosslinking Layer • <A. Vanleenhove, D. Van Steenwinckel, "A litho-only approach to double patterning," Proc. of SPIE Vol. 6520, 65202F, 2007>
As the acid concentration decreases, the crosslinking layer thickness decreases. Double Patterning Usinga Protective Crosslinking Layer • <A. Vanleenhove, D. Van Steenwinckel, "A litho-only approach to double patterning," Proc. of SPIE Vol. 6520, 65202F, 2007>
<Target Feature 70 nm> • <Target Feature 55 nm> Double Exposure with Linear Resist • <Target Feature 60 nm> • <Target Feature 50 nm> • < Emil C. Piscani et al., "Continuing 193nm Optical Lithography for 32nm Imaging and Beyond," Proc. of SPIE Vol. 6924, 69242I, 2008 >
32 nm node SRAM was obtained by Toshiba with using ArF (193 nm) and “custom illuminate condition” 32 nm CMOS Platform Technology with Advanced Single Exposure Lithography • < S. Hasegawa et al., "A Cost-Conscious 32nm CMOS Platform Technology with Advanced Single Exposure Lithography and Gate-First Metal Gate/High-K Process," IEDM 2008 >
32 nm Node and further 45 nm Current Node Conclusion
Thanks, Questions? Conclusion