Better understanding of the effect of radiation on defectivity is essential to improve the stability of Ru-capped MoSi
multilayer blanks. In this work, the effect of radiation exposure on the surface adhesion properties of Ru-capped MoSi multilayers was studied using optical radiation (172 nm, 532 nm, and 1064 nm). Regardless of wavelength, the surface adhesion of defects increases when exposed to radiation and scales with laser power. Changes in adhesion are compared to surface roughness. For different wavelengths, chemical modification of the surface and optical absorption of defects exhibit different contributions.
During their usage and fabrication, EUV masks are exposed to light radiation from λ=13.5 nm up to infrared
wavelengths. During EUV exposure, masks are not only exposed to 13.5 nm radiation but also to out-of-band radiation
which expands from λ=140 to 600 nm for a long period of time. The mask surface is also exposed to different chemicals
during cleaning processes, depending on the usage of the mask. During its effective life, an EUV mask should undergo
many cycles of cleaning and radiation. Consequently, the Ru surface is modified by photon energy (wavelength) as well
as number of photons (intensity and energy). This modified Ru surface will react with chemicals in different ways.
Exposure to 172 nm light followed by Ammonium Hydroxide/ Hydrogen peroxide/ water mixture (APM) will result in
0.5% loss of EUV light while 172nm light exposure followed by Sulfuric acid /Hydrogen peroxide mixture (SPM) will
reduce EUV reflectivity by 3%. Higher radiation energy on the order of 200 Joules will damage the Ru surface and cause
increased defectivity at the mask surface. In addition, higher radiation energies will result in thermal effects such as
formation of Ru silicide and Mo silicide. Ru oxidation valence also depends on the radiation power and radiation
wavelength. In the absence of radiation or low energy radiation, RuO3 is preferred oxidation state but RuO is preferred in
the higher radiation energies. Comparison between 532 nm and 1064 nm radiation showed that RuO2 is the preferred
oxidation state at a wavelength of 532 nm, despite much lower radiation power.
The optical and structural properties of InN layers grown by 'High Pressure Chemical Vapor
Deposition' (HPCVD) using a pulsed precursor approach have been studied. The study focuses on
the effect of ammonia precursor exposure time and magnitude on the InN layer quality. The samples
have been analyzed by X-ray diffraction, Raman scattering, infra red reflectance spectroscopy and
photoluminescence spectroscopy. Raman measurements and X-ray diffraction showed the grown
layers to be single phase InN of high crystalline quality. The E2(high) Raman mode showed
FWHM's as small as 9.2 cm<sup>-1</sup>. The FWHM's of the InN(0002) X-ray Bragg reflex in the 2Θ-Ω-
scans were around 350 arcsec, with rocking curve values as low as 1152 arcsec Photoluminescence
features have been observed down to 0.7 eV, where the low energy cutoff might be due to the
detector limitation. The analysis of the IR reflectance spectra shows that the free carrier
concentrations are as low as as 3.3•10<sup>18</sup> cm<sup>-3</sup> for InN layers grown on sapphire substrates.