ARTICLE SEPTEMBER 2001

EUV lithography as one of the key technological priorities for Europe's Microelectronics future

A) Market trends / user expectations

Lithography is the key enabler for the semiconductor industry and a significant economic factor representing over 35% of chip manufacturing costs. Optical lithography will be the mainstream technology down to 100-nm and 70-nm dense lines with the use of respectively 193-nm and 157-nm wavelength tools.

Optical lithography will be superseded by one or two of several possible next generation lithography (NGL) technologies. The main candidate technology is extreme ultra violet (EUV) lithography.

EUV, which uses electromagnetic waves for the pattern transfer, is no longer a simple extension of "optical" lithography and has quite some complications, since at these wavelengths a fully reflective system has to be designed:

• A new light source for a wavelength around 13 nm has to be developed, for which several alternatives do exist. But neither of these alternatives fulfils the requirement of a lithography system.

• For optical lithography, refractive optics are being used for the illumination and for the imaging system. For EUV lithography, reflective elements have to be developed for a wavelength for which no mirrors have been required until now.

• Even the mask blank has to be a reflective element.

Of course for a new system the whole sequence of R&D process steps also has to be reworked, requiring R&D for a new more precise alignment and positioning system; integration of all the parts into an exposure tool; R&D on a mask fabrication procedure and a mask-keeping-clean system; and R&D on the lithography process (resist technology) with 13 nm wavelength for 50nm structures and below.

B) MEDEA+ View on "Lithography"

Europe is well positioned in the field of lithography with the world-leading wafer-stepper supplier, leading optical companies for light sources and imaging systems and mask manufacturing facilities with extraordinary know-how, and additional competences at many universities and institutes.

The objective of the European partners in this domain is global leadership in lithography in the course of the MEDEA+ programme.

The challenges to develop one single NGL solution are huge. Cost for the development of tool and infrastructure will approach ? 1 billion. Financial and technological risks in all areas involved cover the whole route up to a first working system.

C) MEDEA+ activities / projects in this work area

The heavy workload for EUV in MEDEA+ is concentrated on four projects: source, exposure tool, masks, processing, three of which have commenced in mid 2001. The MEDEA+ activities will build on research results gained in the EUCLIDES project in 1999 and 2000 as part of the IST programme of the European Commission and on the results of the French national project PREUVE.

It is mandatory that the MEDEA+ projects are closely linked. The work packages and the milestones of the individual projects must very well fit together in order to achieve an optimal result. Therefore a Cluster Steering Committee has been installed which will have to carefully monitor all the activities in the projects and to take actions, if some problems within the projects appear or if changes in the global scene of lithography might influence the objectives of the MEDEA+ projects.