Although declared dead several times over the past years, the famous “Moore’s law” still determines the miniaturization trends in semiconductor microchip design and production. The 14nm node currently is being introduced in mass fabrication and the 9nm node is in the development phase. Deep UV (193nm) still is used for optical lithography in production but becoming more complicated and costly due to multiple exposures required for small structures. Extreme UV (EUV, 13.5nm) is expected to be used for next generation chip production but this requires apart from newly designed steppers new photoresists and photomasks.

At the Swiss Light Source (SLS) at PSI we built up a dedicated beamline producing radiation in the EUV regime with an exposure end-station housed in a clean room. This allows – via “interference lithography” where two or more coherent beams create periodic interference patterns – to study newly developed photoresists in terms of resolution, sensitivity, contrast or line edge roughness. Gratings or dot patterns with feature-widths in the single-digit nanometer range routinely can be produced in resists with a single shot exposure over areas of several hundred µm square. Some examples of exposed structures will be given in the talk. Another partly still unsolved problem in EUV lithography is the inspection of photomasks for defects. Since EUV is heavily absorbed by almost any material, the photomasks cannot work as usual in transmission mode but have to be used in reflection mode. Various types of defects can occur like amplitude- or phase defects. For their localization and identification we are developing a ptychographic imaging concept which will allow actinic mask inspection at EUV wavelength with a resolution in the nanometer regime. The concept and some first results will be given in the talk.