Optimization of x-ray sources for proximity lithography produced by a high average power Nd:glass laser

Abstract

We measured the conversion efficiency of laser pulse energy into xrays from a variety of solid planar targets and a Xe gas puff target irradiated using a high average power Nd:glass slab laser capable of delivering 13 IIS FWHM pulses at up to 20 J at 1.053 pm and 12 J at 0.53 pm. wavelength band, including L-shell emission from materials with With 1.053 pm a maximum conversion of 10% into 2n; sr was measured from solid Xe and type 302 stainless steel targets. At 0.527 pm efficiencies of 12-18%/(2~ sr) were measured for all of the solid targets in the same wavelength band. The x-ray conversion efficiency from the Xe gas puff target was considerably lower, at about 3%/(27c sr) when irradiated with 1.053 pm. . .Targets where chosen to optimize emission in the 9-19 A yr . atomic numbers in the Z=2430 and M-shell emission from Xe (Z=54).

X-ray yields from Xe clusters heated by short pulse high intensity lasers

“…We attributed this to the strong M-shell emission bands in Xe in the 8-15 Å range ͑0.8-1.6 keV͒. 5 Strong emission in this wavelength range has been previously observed in Xe cluster targets heated with a high intensity, 300 fs KrF laser. 12 This is the wavelength range of particular interest for proximity lithography applications.…”

“…3 The x-ray emission properties of gas targets have also been investigated, 4 though gases in general do not emit x rays as strongly as solids. 5 Very recently, experiments examining the x-ray emission resulting from the intense irradiation of gases composed of atomic clusters of a few hundred to a few thousand atoms per cluster have been reported. 6,7 These interactions appear to be quite different than laser interactions with either solids or monomer gases.…”

Evaluation of laser-irradiated Ar clusters as a source for time-resolved x-ray studies

“…[1][2][3][4][5][6][7][8][9][10][11] The high average x-ray flux gives reason for optimism when it comes to using laser-irradiated clusters as a source for relatively hard x rays ͑Ͼ1 keV͒. Possible application fields are lithography 12 and x-ray microscopy. The interaction of intense laser radiation with clusters is now well understood through a model first described by Ditmire et al 4 In this model each cluster is treated as a small plasma ball, a few nanometers in size.…”

Development of a compact laser-produced plasma soft X-ray source for radiobiology experiments

“…Among them, for examples, were production of efficient EUV [24] and X-ray [25] emissions for lithography [26], metrology [27,28], microscopy [29][30][31], radiography [32,33], tomography [34], micromachining [35,36], processing materials [37], etc. Similar techniques with modifications in the experimental setup have been used to develop a source dedicated for radiobiology experiments.…”