Characterization of out-of-band radiation and plasma parameters in laser-produced Sn plasmas for extreme ultraviolet lithography light sources

Out-of-band (OOB) radiation, in contrast to the in-band radiation at 13.5 nm in a 2% bandwidth, emitted from dense tin plasmas generated by a laser was investigated for application as an extreme ultraviolet lithography light source. It was found that the continuum spectrum, which overwhelms the atomic and ionic line emissions, is responsible for the intense OOB radiation. The spectral distribution of the continuum emission matches that of blackbody radiation with a temperature of about 10 eV. The OOB radiation can be considerably suppressed by employing a minimum-mass target and short-pulse laser irradiation. Spectroscopic observations were made to examine the spatiotemporal behavior of the plasma immediately after laser irradiation. Prominent line broadening due to the Stark effect in the high-density plasma was observed, from which the variation of the electron density was deduced. The electron density and temperature on the target surface were 1017–1018 cm−3 and a few eV’s, respectively, in the first 2...

[1]  Ivan O. Antonov,et al.  Effective operation of subsonic COIL with N2 and CO2 buffer gases , 2007, Laser Optics.

[2]  Hiroki Tanaka,et al.  Comparative study on emission characteristics of extreme ultraviolet radiation from CO2 and Nd:YAG laser-produced tin plasmas , 2005 .

[3]  Eiki Hotta,et al.  Estimation of optimum density and temperature for maximum efficiency of tin ions in Z discharge extreme ultraviolet sources , 2007 .

[4]  Martin Richardson,et al.  High conversion efficiency mass-limited Sn-based laser plasma source for extreme ultraviolet lithography , 2004 .

[5]  F. Bijkerk,et al.  Absolute calibration of a multilayer-based XUV diagnostic , 2002 .

[6]  S. S. Harilal,et al.  Emission characteristics and dynamics of neutral species in a laser-produced tin plasma , 2007 .

[7]  Vivek Bakshi,et al.  EUV Sources for Lithography , 2006 .

[8]  Kunioki Mima,et al.  Properties of ion debris emitted from laser-produced mass-limited tin plasmas for extreme ultraviolet light source applications , 2005 .

[9]  R. Bengtson,et al.  Experimental transition probabilities and Stark-broadening parameters of neutral and singly ionized tin , 1979 .

[10]  Mark S. Tillack,et al.  Spectral control of emissions from tin doped targets for extreme ultraviolet lithography , 2006 .

[11]  A. Cummings,et al.  13.5 nm extreme ultraviolet emission from tin based laser produced plasma sources , 2006 .

[12]  Jeroen Jonkers,et al.  High power extreme ultra-violet (EUV) light sources for future lithography , 2005 .

[13]  Kazuya Ota,et al.  EUV Source Requirements for EUV Lithography , 2006 .

[14]  P. K. Carroll,et al.  New continua for absorption spectroscopy from 40 to 2000 A. , 1978, Optics letters.

[15]  P. Silverman.  Extreme ultraviolet lithography: overview and development status , 2005 .

[16]  Kunioki Mima,et al.  Spectroscopic study of debris mitigation with minimum-mass sn laser plasma for extreme ultraviolet lithography , 2006 .

[18]  A. Srećković,et al.  Stark widths and shifts of SnI, HgII, HgIII and PbII spectral lines , 1992 .

[19]  Kunioki Mima,et al.  Absolute evaluation of out-of-band radiation from laser-produced tin plasmas for extreme ultraviolet lithography , 2008 .

[20]  H. Furth,et al.  Plasma diagnostic techniques , 1965 .

[21]  Martin Richardson,et al.  Studies of high-repetition-rate laser plasma EUV sources from droplet targets , 2003 .

[22]  Tatsuya Ariga,et al.  EUV radiation characteristics of a CO2 laser produced Xe plasma , 2006 .

[23]  P. Di Lazzaro,et al.  High-efficiency clean EUV plasma source at 10–30 nm, driven by a long-pulse-width excimer laser , 2003 .

[24]  Koichi Toyoda,et al.  Laser produced EUV light source development for HVM , 2007, SPIE Advanced Lithography.

[25]  Simon J. Henley,et al.  Studies of the plume accompanying pulsed ultraviolet laser ablation of zinc oxide , 2002 .

[26]  H. M. Hertz,et al.  Debris elimination in a droplet‐target laser‐plasma soft x‐ray source , 1995 .

[27]  Sven Probst,et al.  Integrating Philips' extreme UV source in the alpha-tools , 2005, SPIE Advanced Lithography.

[28]  S. Namba,et al.  Spectroscopic study of ablation and recombination processes in a laser-produced ZnO plasma , 2006 .

[29]  F. Bijkerk,et al.  Multilayer optics with spectral purity layers for the EUV wavelength range , 2006, SPIE Advanced Lithography.

[30]  M. Dimitrijević,et al.  Stark broadening of isolated spectral lines of heavy elements in plasmas , 1983 .

[31]  P. Breger,et al.  Stark broadening of isolated lines emitted by singly-ionized tin , 1980 .

[32]  Mark S. Tillack,et al.  Spectroscopic characterization of laser-induced tin plasma , 2005 .

[33]  D. Geohegan.  Imaging and blackbody emission spectra of particulates generated in the KrF‐laser ablation of BN and YBa2Cu3O7−x , 1993 .

[34]  Padraig Dunne,et al.  Angle-resolved absolute out-of-band radiation studies of a tin-based laser-produced plasma source , 2007 .

[35]  A. Cummings,et al.  A spatio-temporal study of variable composition laser-produced Sn plasmas , 2006 .

[36]  S. Yulin,et al.  Damage resistant and low stress EUV multilayer mirrors , 2001, Digest of Papers. Microprocesses and Nanotechnology 2001. 2001 International Microprocesses and Nanotechnology Conference (IEEE Cat. No.01EX468).

[37]  Igor V. Fomenkov,et al.  LPP EUV source development for HVM , 2006, SPIE Advanced Lithography.