High Density Amorphous Carbon Films and the Preparation of Diamond Membranes for X-Ray Lithography

Abstract

Abstract Trends in recently reported data on high sp 3 fraction (up to 85%), non-hydrogenated amorphous diamond-like carbon films deposited by ion beam sputtering and laser vaporization are examined. The degree of diamond-like film character is found to depend upon the deposition technique as well as the substrate temperature and thermal diffusivity. The data suggest that the combination of incident particle kinetic energy and surface accommodation determine the physical properties of the resultant film. A model is proposed for the condensation of energetic carbon atoms into diamond-like films in which a quench-type surface accommodation mechanism is operative. Diamond Membranes are being developed for x-ray lithographic masks. Typically, these 1-3 micron thick membrane films are deposited onto silicon substrates using microwave driven plasmas. To obtain smooth films with uniform tensile stress, spray and electrophoretic deposition of 0.1 micron diamond seeds were used to control the initial nucleation and growth of the diamond films. The films have a room temperature tensile stress of 25 to 125 MPa. The temperature dependence of the stress is due to the tensile growth stress of the diamond film and the thermal stress of the diamond-silicon layer structure. The films have a biaxial modulus of 800 GPa. X-ray lithography masks have been made and used to print patterns with x-rays from a synchrotron source.