Intense vacuum ultraviolet emission at 172 nm from LaF3 : Nd3+ crystals

Intense vacuum ultraviolet (VUV) radiation from 168 to 177 nm was obtained from a LaF3:Nd3+ crystal when it was excited with a molecular fluorine lase r at 157 nm. VUV emission is due to the strong 4f(n-1)5d --> 4f(n) intercon figurational transitions of the Nd3+ ions. This work was motivated by the f act that the absorbances of most carbonated polymeric materials have just t he right value of similar to 0.4 mum(-1) for lithographic imaging in the sp ectral region above 170 nm. In addition, the resist out-gassing is less in this spectral region in comparison to 157 run. The photon conversion effici ency from 157 to 168-177 nm by the LaF3:Nd3+ crystal depends strongly on th e crystal purity. (C) 2001 Elsevier Science B.V. All rights reserved.