Lithography applications beyond EUVL are expected to use 6.72 nm radiation. In this spectral region no transparent materials exist, therefore mirrors have to be used as optical elements. Spacer materials of interest in reflective optics for λ > 6.65 nm are B and B4C. Simulations show that La is a suited refractive material, because of its relatively low absorbtion and high optical contrast with B and B4C.
|Patent number||# US 61/079307 (US); # DE102008040265 (Germany)|
|Publication status||Submitted - 2010|