Influence of secondary effects on the structure quality in deep X-ray lithography

Abstract

In deep X-ray lithography, synchrotron radiation is applied to pattern several hundred micrometer thick resist layers. This technique has been used to obtain micro structures with an aspect ratio up to 100. The structures are characterized by straight walls and a typical surface roughness in between 30 to 50 nm, which are a consequence of the small divergence of synchrotron radiation and the high selectivity of the resist-developer system. The precision of the microstructures are affected by photoelectrons which are generated in the resist and by diffraction of the synchrotron radiation at the absorber structures. Secondary radiation which is generated during the irradiation in the X-ray mask and the substrat, as well as the heat load, which arises from the absorbed X-rays in the mask and the resist determines the quality of the micro structures.