Physics and Technique of Nanometer Scale IC Element Formation Processes Based on the Interaction of Intensive EUV Radiation with Matter
Tech Area / Field
- INF-ELE/Microelectronics and Optoelectronics/Information and Communications
8 Project completed
Senior Project Manager
Russian Academy of Sciences / Physical Technical Institute, Russia, St Petersburg
- NIIEFA Efremov, Russia, St Petersburg\nVNIIEF, Russia, N. Novgorod reg., Sarov\nVavilov State Optical Institute (GOI) / Research Institute for Laser Physics, Russia, St Petersburg
- JENOPTIK, Germany, Jena\nASET - Association of Super-Advanced Electronics Technologies, Japan, Nagoya
A goal of this project is invention and development of the new type of a lithographic tool capable to produce very large and high speed ICs with characteristic dimensions of the pattern up to 20-50 nm by means of simultaneous and parallel transfer of integral circuit image.
As a base of project the extreme ultraviolet (EUV) radiation in spectral interval 11-14 nm has been chosen as a tool for image formation of IC pattern, using reflecting optics and step-and-scan mode of operation. A EUV radiation source is a laser-produced plasma generated by a radiation of a powerful, high repetition rate laser, focused on a special target or on a cryogenic pellet of rare gases. Reflecting optics with multilayer coatings will be implemented for imaging system and mask. The mask is supposed to be manufactured by traditional electron lithography methods, and its image will be demagnified by a factor of M=5-20.
Similar projects are now under development in a frame of large-scale national programs in USA, Japan and Europe. Many aspects of technology developed in military oriented investigations during last decade are used now to provide the progress in microelectronics. Among them are mainly optical elements and converters for soft-X-ray lasers, powerful excimer and other type of pulsed laser sources.
A projection printing of feature sizes around 50 nm can be considered now as realistic laboratory achievement but many elements of technology are rather far from practical requirements. This is true firstly for intense high frequency laser-produced plasma source capable of providing debris-free operation along with high efficiency of laser light conversion into EUV radiation in relevant spectral interval. Secondly, technology of EUV mask as well as projection and imaging systems must possess unprecedented wave front quality to print 50 nm features.
At the same time, in our opinion, the most important and undeveloped area of EUV projection lithography is a problem of photoresist in a corresponding spectral range having high sensitivity and contrast. It is especially actual in the sense, that the optical reducing systems of the Schwarzschild type do not have enough numerical aperture and its typical number is less then 0.1. This results in a worse than 0.1 mkm final resolution already achieved by the traditional methods.
Circumstances mentioned above, predetermine a concentration of main efforts of the project on a study of EUV radiation interaction with surface-imaging materials to search out most effective and super contrast resist in EUV spectral interval. We proceed from assumption that the low numerical aperture of projection system can be compensated by a high contrast in the image pattern transfer. The good reason for above assumption is a new effect recently found and investigated in Ioffe Institute. The effect consists in the enhancement of the image transfer contrast in processes of high energy photon interaction with some inorganic films. Theoretical model of this effect developed now enables one to expect that super contrast property can be realized in rather wide class of inorganic materials suitable for resist in VUV and EUV spectral ranges.
At the same time consistent and total fulfillment of the goal of projects can not be developed without complex tackling all problems in direction of practical development of modern lithography tool, in the sense that nonlinear nature of processes in thin film materials makes it very sensitive to all parameters of VUV and EUV radiation. So, to accomplish a project goal, an experimental model of lithography setup has to be made. It demands to solve some problems mentioned above. The feasibility of EUV lithography depends on the advances in four critical technological direction:
· intensive pulsed high repetition rate laser with effective focusing system;
· debris-free efficient laser-produced plasma source;
· aspheric optic fabrication with image correction;
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