double exposure/patterning lithography
DESCRIPTION
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.TRANSCRIPT
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Double Exposure/Patterning Lithography
Hongki Kang
EE235 Mar 9 2009
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Resolution
NA (Numerical Aperture) For higher resolution, R↓, λ↓, n↑, and α↑. ArF source (193 nm)
<Trend of k1 factor reduction since 2001,from Nanofabrication: Principles, Capabilities and Limits by Zheng Cui 2008>
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Lithography Challenge ITRS 2007 Lithography
32 node
Single Exposure - No solution yetDouble Exposure - Solutions exist
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What’s DE and DP?
<(a) single exposure, (b) double exposure, (c) double patterningfrom Nanofabrication: Principles, Capabilities and Limits by Zheng Cui 2008>
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What’s DE and DP?Double Exposure Double Patterning
Advantages
- Can separate one dense feature into two less dense features (higher resolution possible with using current lithography system)- No considerable changes in infrastructure => more economical than other approaches (λ, NA…)- Keep the same depth of focus
- Much simpler than Double Patterning - Current photoresist can be used
Drawbacks
- The discrepancy and delay between the second PR pattern and the first hardmask pattern, resulting in an additional source of variation
- Well developed non-linear resist is needed (propagation of photon energy) - Additional steps causes longer process
time and low throughput
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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>
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Double Patterning Usinga Protective Crosslinking Layer
<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.>
<A. Vanleenhove, D. Van Steenwinckel, "A litho-only approach to double patterning," Proc. of SPIE Vol. 6520, 65202F, 2007>
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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
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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
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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.
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Double Exposure with Linear Resist
< Emil C. Piscani et al., "Continuing 193nm Optical Lithography for 32nm Imaging and Beyond," Proc. of SPIE Vol. 6924, 69242I, 2008 >
<Target Feature 70 nm>
<Target Feature 60 nm>
<Target Feature 55 nm>
<Target Feature 50 nm>
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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 SRAM was obtained by Toshiba with using ArF (193 nm) and “custom illuminate condition”
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Conclusion
Current Lithography
Advanced Single
ExposureDouble
ExposureDouble
Patterning
32 nm Node and further
45 nmCurrent Node
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Conclusion
Thanks,Questions?