EUV lithography for next
generation IC manufacturing
Sometime around 2005 to 2007, optical pattern transfer lithography for
integrated semiconductor manufacturing is expected to reach its technical and economic
limits below 70 nanometers (nm). The favourite technique to take over from optical
lithography is Extreme Ultra Violet (EUV) lithography.
The EUCLIDES project is working to overcoming obstacles to building EUV lithography
tools. The project plan is to lay the foundations for EUV exposure tools which ultimately
offer a resolution down to 30 nm, a throughput of greater than forty 300 mm wafers an
hour, a CD control of 3 nm and an overlay budget of 10 nm (both 3 sigma).
EUV works at a much shorter exposure wavelength (about 13 nm) than for example Deep
Ultra Violet (DUV) lithography (248 and 193 nm at present). Therefore radiation will not
pass through the reticle and illumination and projection lenses onto the wafer, as there
is almost no refraction and too much absorption loss and radiation damage. The solution is
to use aspheric reflecting mirrors and also reflecting reticle both with reflecting
multi-layer coatings. This puts unprecedented accuracy requirements onto mirror and
reticle fabrication to ensure correct imaging.
Visitors to the EUCLIDES stand can examine an aspheric ceramic mirror substrate from a
multi-mirror x-ray space telescope - an example of how findings from other areas such as
satellite telescopes in space can be applied to the microelectronics arena.