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HIGH RESOLUTION:
UHRL uses the SWEET SPOT in the transmitted current. Notice the pinch and high contrast. UHRL refers to the reduction in printed feature size, or "demagnification" obtained by the use of "bias".
Field is not demagnified, but kept compact at both mask and wafer.
DENSE LINES:
Pitch is kept small by rapid multiple exposures and single development
NEEDS: a lithography system with
HIGH RESOLUTION
LOW COST
HIGH THROUGHPUT
HIGH YIELD and
DEMONSRATED
UHRL is
Demonstrated in proximity X-ray lithography with generic importance to all lithographies using out of focus imaging to produce ultra high resolution.
Uses new meaning for Next Generation Lithography (NGL) in terms of relaxation of fidelity in the reproduction of masks.
Makes use of modern control in development of resists.
Applying Fresnel diffraction for the first time in this context, mask pattern features are "demagnified" by "bias". Classically, bias is minimized but UHRL uses it to advantage.
In consequence:
Mask-wafer gaps are enlarged to 15-30 micrometers (most serious limitation for extensibility). Gap proportions with the square of the demagnification factor.
Mask features enlarged to 3x-6x (cf. classically 1:1 in proximity lithography).
Extensible to 15 nm print feature sizes (providing the advantage over competing lithographies), and
Demonstrated to 45 nm with 3.5x demagnification, and to 25 nm with 6x demagnification.
Exposure times reduced and throughput increased.
Demonstrated nested lines with double exposures.
Physics shows exposure is stable. Whereas printing contrast is low with old fashioned 1X proximity, the contrast is maximized in 3X UHRL printing with MASC.
UHRL can be applied using point sources.
Background
The breakthrough is applied to the field of Micro-Lithography as the major tool in development and production of micro-electronic devices and integrated circuits.
Lithography, the printing of patterns on surfaces, is both a driving force and a bottleneck in semiconductor manufacturing and in microfabrication. Classical lithography is based on the concept of fidelity in reproducing the mask pattern onto the wafer. Shrinking critical dimension (CD) requirements in semiconductor manufacturing demand development of lithographic techniques producing desired patterns not necessarily being a mask pattern replica. Next Generation Lithography (NGL) implies the departure from the classical concept of replication fidelity.
Among NGLs competing for sub-100 nm patterning, proximity X-ray lithography (PXL) is the most advanced and mature. PXL was first introduced as a Post Optical Lithography and unavoidably inherited the classical tendency of replication fidelity. Restricted by this concept, PXL was thought to be limited to 70-75 nm imaging and printing capability at the smallest working mask/wafer gaps of 7-10 um. The breakthrough achieves ultra-high resolution beyond 25 nm by applying the concept of NGL.
Projection
As the technology is the most mature NGL, development is advanced and cutting edge.
Owing to absence of lenses, system cost is moderate and conventional.
With compact, broadband, synchrotron sources - naturally collimated by relativity - throughput is high and conventional (100 times projection EUV with equivalent capitalization).
This is the solution for the cost squeeze in cutting edge.
Capability
Our Consortium is planning to supply an exposure station on a synchrotron at extraordinarily modest cost. The station will be operate with SMIF nodes for both masks and wafers and designed for 30 wph at 45 nm (extensible to 22 nm and 60 wph).
Alternative? None that fulfills needs.
Worldwide, 130nm lithography reports yield problems. Informed people know the cost of EUVL is excessive and its throughput minuscule. UHRL, or Near Field X-ray, extends beyond all of those. X-ray is the only developed NGL.
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References
Solid State Technology, World News, February 2000 pp. 18-23, A Breakthrough in X-ray Lithography
J. Phys D: Appl.Phys. 36 2471-2482 (2003) Near field X-ray lithography simulations for printing fine bridges
A.J.Bourdillon, C.B.Boothroyd, G.P.Williams and Y.Vladimirsky
Proc SPIE Microlithography 2003, 22nm Lithography using Near Field X-rays, SPIE vol 5037 pt II, pp 622-633, Santa Clara, Feb 23-27, 2003
see also Proc. SPIE vol 5374 pp. 546-557, 2004
A.J.Bourdillon, C.B.Boothryd, G.P.Williams and Y.Vladimirsky,
J.Phys.D: Appl.Phys. 33 1-9 (2000), A Critical Condition in Fresnel Diffraction Used for Ultra-High Resolution Lithographic Printing, A.J.Bourdillon, C.B.Boothroyd, J.R.Kong and Y.Vladimirsky
J. Phys. D: Applied Physics, 32 L114-L118 (1999), Demagnification in Proximity X-ray Lithography and Extensibility to 25 nm by Optimizing Fresnel Diffraction, Y.Vladimirsky, A.J.Bourdillon, O.Vladimirsky, W.Jiang and Q.Leonard
J.Phys D: Appl. Phys, 34 3209-3213 (2001), Proximity Correction Simulations in Ultra High Resolution Lithography,
A.J.Bourdillon and C.B.Boothroyd
Nanotechnology,(2002)Optimum Demagnification in Ultra High Resolution Lithography. A.J.Bourdillon
Proc SPIE Conf Microlithography, 27Feb-3Mar 2000, Demagnification-by-bias in Proximity X-ray Lithography, J.R.Kong, Q.Leonard, Y.Vladimirsky and A.J.Bourdillon
US Patent Nr 6383697: Ultra High Resolution Lithographic Imaging and Printing and Defect Reduction by Exposure near the Critical Condition Utilizing Fresnel Diffraction.
Proc SPIE Conf Microlithography, 27Feb-3Mar 2000, Demagnification-by-bias in Proximity X-ray Lithography, J.R.Kong, Q.Leonard, Y.Vladimirsky and A.J.Bourdillon
Proc MNE 2000, Sep 18-21, Jena, Germany, Low k-Factor in Proximity Imaging for X-ray Lithography Resolution Enhancement, J R Kong, Y Vladimirsky and Q Leonard
SPIE 2001 Short Course Notes # SC099. X-ray Lithography; part 2 : Image Formation and part 8 Appendix II Recent Advances in X-ray Lithography. Y.Vladimirsky
Personnel
Antony Bourdillon took his degrees at Oxford University, UK, and researched for 10 years at Cambridge University, where he was permanent faculty before becoming a full professor in engineering in New York. He has directed two major laboratories in Sydney and Singapore where, as a professor of physics, he proposed and built the Singapore Synchrotron Light Source and where he assembled an expert team.
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Contact
Antony J. Bourdillon MA DPhil(Oxon) PhD(Cantab)
President
UhrlMasc Inc
P.O.Box 700001
San Jose, CA 95170-0001
fax/tel: (408) 777 0577
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