SILICON-GERMANIUM FILMS FOR PHOTOMASKING APPLICATIONS

Si-Ge films have been deposited by RF co-sputtering and have been comp ared to Cr films for use as opaque materials on photomasks. One of the potential attractions of Si-Ge is its ability to be patterned by dry etch, anisotropic processing. Optical absorption coefficients were mea sured from 347 to 820 nm using a modified spectrophotometer. The absor ption coefficient of Si-Ge films (containing 32.6% Ge) was 1.5 x 10(5) cm-1 whereas the 'standard' Cr gave 5.6 x 10(5) cm-1. A simple scratc h test was used to compare the adhesion of the films to fused silica s ubstrates. Specially fabricated cantilevers were used to study interfa cial stress between films and substrates. Cr and Si-Ge with similar th icknesses exhibited tensile and compressive stress, respectively. Thes e observations have confirmed the potential of Si-Ge as a photomask op aque.