A Novel Objective for EUV Microscopy and EUV Lithography

Web Published:

A Novel Objective for EUV Microscopy and EUV Lithography

Princeton Docket # 14-2950


Researchers at Princeton Plasma Physics Laboratory (PPPL) have proposed a novel device for extreme ultraviolet (EUV) spectroscopy, EUV microscopy, and EUV lithography at wavelengths below 100 nm. Princeton is seeking an industry partner to develop and commercialize this technology.


This new EUV device consists of two concentric, concave and convex spherical mirrors or reflectors and can be assembled and aligned using standard procedures for the assembly and alignment of optical components. By eliminating the shortcomings of presently used optical systems, this new device could lead to substantial advancements and cost savings in the manufacturing process, and make significant contributions to EUV lithography at wavelengths in the range from 10 to 15 nm, which is being developed for the manufacture of next-generation integrated circuits.


One advantage of this new EUV device is that the Bragg reflecting areas of the reflectors are maximized due to the fact that the Bragg condition is simultaneously fulfilled at every point on the two multi-layer reflector surfaces. It should be possible to image the entire object onto a wafer in a single exposure. By contrast, the conventional Schwarzschild devices, which are being considered for the manufacture of next-generation integrated circuits, can satisfy the Bragg condition only locally over a small part of the multi-layer areas. An image of the entire object can only be obtained in multiple exposures by moving both mask and wafer synchronously through an EUV beam of a relatively small cross-section.


Other important advantages of this new EUV device are that the angles of incidence (or Bragg angles) are arbitrary and that the astigmatism is fully eliminated for any choice of Bragg angles. By contrast, Schwarzschild devices are restricted to the use of paraxial rays, since severe image distortions result from even small deviations from normal incidence. It is expected that some optical components presently used with Schwarzschild devices to compensate for the image distortions can be eliminated, so that the EUV transmission will be significantly improved. Also, the magnification or de-magnification obtained with this new EUV objective is uniform in all directions, so that the images of the mask, i.e., the printed circuits, are true to scale.


Princeton Plasma Physics Laboratory (PPPL)


The U.S. Department of Energy's Princeton Plasma Physics Laboratory (PPPL) is a Collaborative National Center for plasma and fusion science. Its primary mission is to develop the scientific understanding and the key innovations which will lead to an attractive fusion energy source. Associated missions include conducting world-class research along the broad frontier of plasma science and providing the highest quality of scientific education.



 ·         Next generation Integrated circuit manufacturing in the range of 10-15 nm


·         Single exposure imaging


·         Cost savings


·         Magnification and demagnification is uniform in all directions


·         No fundamental change to existing technology


·         Astigmatism is eliminated


M. Bitter, K. W. Hill, and P. Efthimion, “A Novel Objective for EUV Microscopy and EUV Lithography: Working Principle and Design Studies for a Plasma Diagnostic Application”, Internal Note (pdf-file).


Faculty Inventor


Manfred Bitter is a Principal Research Physicist at the Princeton Plasma Physics Laboratory (PPPL) of Princeton University. He joined PPPL in 1977 after previous appointments at the European Space Organization in Frascati, Italy from 1969 to 1973 and the Centre des Recherches en Physique des Plasmas in Lausanne, Switzerland from 1973 to 1977. He was educated in Germany, where he received a diploma in physics (‘Diplom-Physiker’) from the Ludwig Maximilian Universität in Munich and a doctorate in physics (‘Dr. rer. nat.’) from the Technische Hochschule in Aachen. His fields of expertise are the physics of highly charged ions and x-ray spectroscopy of hot tokamak plasmas with a particular focus on Doppler measurements of the plasma ion temperatures and plasma flow velocities. For the purpose of these measurements, he invented a (1D) x-ray imaging crystal spectrometer, which provides radial profiles of these important plasma parameters with high spectral and high spatial resolutions. This type of spectrometer is now being used on tokamaks and stellarators worldwide and its design concept has also been adopted for measurements of the profiles of plasma ion-temperatures and plasma flow-velocity profiles in the International Thermonuclear Experimental Reactor (ITER). More recently, he and his colleagues at PPPL, Dr. Kenneth W. Hill and Dr. Phillip C. Efthimion, developed high-resolution spectrometers and 2D imaging systems for the diagnostics of laser-produced plasmas and applications in EUV lithography. Manfred Bitter is a fellow of the American Physical Society since 1985 and was a recipient of the Alexander von Humboldt Award in 1996 and a recipient of the Kaul Prize for Excellence in Plasma Physics in 2012.

Intellectual Property Status

Patent protection is pending.

Princeton is seeking to identify appropriate partners for the further development and commercialization of this technology.


Michael R. Tyerech
Princeton University Office of Technology Licensing • (609) 258-6762•

Laurie Bagley
Princeton University Office of Technology Licensing • (609) 258-5579•



Patent Information:
For Information, Contact:
Chris Wright
Licensing Associate
Princeton University
Manfred Bitter
Kenneth Hill
Philip Efthimion
Opto-Electronics/ELE ENG