6.7-nm Emission from Gd and Tb Plasmas over a Broad Range of Irradiation Parameters Using a Single Laser

Abstract

We report a comprehensive study of the emission from Gd and Tb laser produced plasmas in the 6.5-6.7 nm wavelength region for a broad range of laser irradiation parameters using a single λ = 1030 nm laser with tunable pulse duration in the 120 ps to 4 ns range. The results are of interest for beyond extreme ultraviolet (BEUV) lithography of integrated circuits. BEUV emission spectra were measured as a function of laser pulse duration, emission angle, and

Scaling diode-pumped, high energy picosecond lasers to kilowatt average powers

“…The improved thermal parameters at cryogenic temperatures compensates the larger thickness of this geometry compared to thin disk lasers (a few millimeter vs. a few hundred microns), with the additional advantage of increased pump absorption with reducing the complexity of the pump optics. Using this scheme, we have developed high energy CPA lasers that were used for a number of applications including the first demonstration of a diode-pumped, plasma-based soft X-ray laser [35] , average power tabletop lasers at [48, 49] and 13.9 nm [50] , Laser-induced damage threshold (LIDT) measurements of multilayer coatings [51] , driving a 100 Hz repetition rate, millijoule energy OPCPA at [52] and the characterization of the emission from a laser produced plasma source for beyond EUV (BEUV) lithography [53] .…”

Using Temporally Synthesized Laser Pulses to Enhance the Conversion Efficiency of Sn Plasmas for EUV Lithography

“…The Sn LPP emission was characterized using a EUV diagnosis suite, which is similar to that used in Ref. [28], but adapted for operation at 13.5 nm and expanded to include the capability of time resolved measurements. The energy of emitted EUV radiation was measured by three energy monitors that are positioned in the same horizontal plane that contains the Sn LPP and the irradiation laser at angles of 6 o , 46 o , and 86 o with respect to the target normal.…”

“…6 (a) and (b). However, the spectral emissions of the plasmas generated using the 300 ps pulse is broader and shifted to longer wavelength, because this plasma has a broader range of ion charge states and has the highest mean ionization state among the pulse shapes [28]. This happens as a result of maintaining the laser pulse energy constant for all pulse durations.…”

Thomson scattering measurements of electron temperature and electron density in laser-driven Gd plasmas

“…Theoretical and experimental investigations have estimated that the efficient output of BEUV radiation from Gd plasma should be in the temperature range of 100-120 eV [9][10][11]. To achieve this, laser intensities higher than 10 11 W • cm −2 are required [12,13].…”