Fabrication of Diamond Membranes for X-Ray Masks by Hot-Filament Method

Diamond thin films have been grown on a Si substrate by a hot-filament method with mixtures of CH 4 and H 2 , and properties such as stress and optical transmittance were investigated for free-standing membrane films as a function of methane concentration (0.5-2.0%) and deposition pressure (8-80 Torr). Ellipsometric and Raman scattering measurements were also carried out to evaluate the film structure, and graphite and void components. It has been found that the loss in the optical transparency is mainly due to light scattering at the surface. It is also shown that boron doping is useful for decreasing the film resistivity, which is advantageous for electron beam (EB) writing and inspections.