Influence of phase shift on pattern transfer in X-rax lithography

Waves passing material undergo generally a phase shift besides linear attenuation compared to waves passing the same path in vacuum. In X-ray lithography the phase shift of waves passing a typical absorber layer of an X-ray mask is some pi radians because the refractive index in the soft X-ray region is very close but lower than 1. The phase shift influences the replication of submicrometer absorber patterns especially, when low contrast absorbing layers are used. In this contribution we present a study showing how advantage can be taken by the phase shift effect regarding the replication of sub-half-micrometer patterns. (IMT)