Investigation of phase-conjugated stimulated Brillouin scattering at 248 nm for application to photolithography

Following the novel concept of applying phase conjugate mirrors for lensless imaging we have investigated the feasibility of such devices in connection with KrF excimer lasers for production of high resolution images. Since the beam characteristics of currently available excimer lasers lack sufficient quality we employed stimulated Brillouin scattering rather than four wave mixing for generation of phase conjugated waves. Various scattering media both liquid and gaseous with large gain coefficients were used. With gaseous SF6 pattern transfer of 80 sm lines was demonstrated. With the used experimental arrangement the system resolution was limited to 40 m. However with improved equipment higher resolution is possible. In particular the laser beam quality has to be controlled very carefully since an inhomogeneous intensity profile causes medium changes and breakdown resulting in low efficiency and poor quality backscattering. 1.