Double Exposure/Patterning Lithography
description
Transcript of Double Exposure/Patterning Lithography
Double Exposure/Patterning Lithography
Hongki Kang
EE235 Mar 9 2009
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>
Lithography Challenge ITRS 2007 Lithography
32 node
Single Exposure - No solution yetDouble Exposure - Solutions exist
What’s DE and DP?
<(a) single exposure, (b) double exposure, (c) double patterningfrom Nanofabrication: Principles, Capabilities and Limits by Zheng Cui 2008>
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
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>
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>
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 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>
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”
Conclusion
Current Lithography
Advanced Single
ExposureDouble
ExposureDouble
Patterning
32 nm Node and further
45 nmCurrent Node
Conclusion
Thanks,Questions?