SiC/SiN multilayer membrane for X-ray mask deposited by low pressure chemical vapor deposition

SiC/SiN multilayer membranes consisting of SiC and thin SiN layers were prepared using hot-wall, low-pressure chemical vapor deposition (LPCVD) for synchrotron radiation (SR) lithography. The SiC/SiN multilayers had advantages such as uniformity in the controlled film stress, good surface morphology and optical transmittance of over 60% at film thicknesses from 1.7 to 2.5 mu m. The optical transmittance of over 80% with an antireflection coating (ARC) was obtained. X-ray masks were fabricated using the SiC/SiN multilayer membranes and W films as absorber. The 80-nm-feature patterns on the resist films were obtained by electron beam (EB) lithography. SR durability of the X-ray masks using the SiC/SiN multilayer was discussed assuming a stress change in the thin SiN layers.