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This chapter describes an EUVL technology that is expected to be introduced into the manufacturing of the 32 nm-node device from 2009–2011. EUVL consists of a light source of 13.5 nm, a reflective mask, objective optics and wafer. A reflective mask and objective optics with multilayer coating are employed. The reflectivity of multilayer at the wavelength of 13.5 nm is 68%.

The challenging items are high power source, defect-free mask and resist with low LER and high sensitivity. EUV scanner of α-type have delivered and process studies are performed in several institutions. In this chapter, the principle of EUV lithography, concepts of optics design, aspherical mirror fabrication and measurement, mask fabrication process and inspection, recent activities of resist and source are described.

Frequency comb lasers in the infrared region of the spectrum have revolutionized many fields of physics. We demonstrate for the first time direct frequency comb spectroscopy at XUV wavelengths. Generation of an XUV comb is realized by amplification of two pulses from a frequency comb laser in a parametric amplifier, and subsequent high-harmonic generation to 51 nm (15^th harmonic). These XUV pulses, with a time separation between 5.4 and 10 ns, are then used to directly excite helium on the 1s²¹S₀ - 1s5p ¹P₁ transition. The resulting Ramsey-like signal has up to 60% modulation contrast, indicating a high phase coherence of the generated XUV comb light.