Optical Characteristics of Nano-crystalline Diamond Films as X-ray Lithography Masks for Integrated Circuit Fabrication

In this paper, the structure, morphology and optical properties of nano-crystalline diamond (NCD) films, deposited by hot-filament chemical vapor deposition (HFCVD) method under different carbon concentration, are investigated. With increasing the carbon concentration during the film deposition, the diamond grain size is reduced and thus a smooth diamond film can be obtained. According to the data on the absorption coefficient in the wavelength range from 200 to 1100 nm, the optical gap of the NCD films decreases from 4.3 eV to 3.2eV with increasing the carbon concentration from 2.0% to 3.0%