RADIATION STABILITY OF SIC AND DIAMOND MEMBRANES AS POTENTIAL X-RAY-LITHOGRAPHY MASK CARRIERS

In this paper we report on the radiation stability of silicon carbide and diamond membranes as potential x-ray lithography mask carriers. Silicon carbide membranes have been produced by epitaxial chemical vapor deposition (CVD). Diamond membranes have been produced in tension with diameters up to 2.5 cm using a microwave plasma CVD process. The stability of these membranes upon exposure to x rays has been studied. The materials were characterized before and after irradiation for their stress, Young's modulus, infrared absorption from 2.5 to 25-mu-m, and visible transmission from 300 to 800 nm. The x-ray exposures were performed using the Center for X-ray Lithography beamlines at the Aladdin synchrotron at the University of Wisconsin. These beamlines provide a broadband x-ray spectrum from 900 to 5000 eV. Incident doses of 6700 and 2400 J/cm2 were delivered to the silicon carbide and diamond samples, respectively. Both materials were found to be stable for these exposure levels within the accuracy of the experimental methods.