Patterning of Ta/SiO2 high transmission EAPSM material for 193nm technology

For the new Schott EAPSM Material, comprising a Ta/SiO 2 /Cr stack, a patterning process has been developed. The material offers the advantage of an independent adjustment of phase shift and transmission and is applicable for different wavelengths. Because of very homogenous Ta and SiO 2 films and perfect etch selectivities it has been achieved a phase shift uniformity of 1.1° and a tight transmission deviation of 0.34% (absolute) across the entire mask. First dry etch process development has been focused on profiles and selectivities. The influence of process parameters on sidewall angle, profile bow, resist loss and Cr loss of the three patterning steps are shown. We have achieved excellent selectivities and a final sidewall angle of > 88°. The aerial image contrast of the first test plate is comparable to known attenuated phase shift material.