Temperature Rise during Film Deposition by rf and dc Sputtering

Abstract

The temperature rise during film deposition by rf sputtering of Ta, Au, and Pd films and dc sputtering of Ta films has been investigated. The film temperature was measured for various cathode to anode distances, as a function of applied power used for sputtering and sputtering time. It was found that by sputtering from water-cooled cathodes at power levels between 0.1 and 2 kW, the contribution due to radiation from the plasma and the cathode is negligible. To a first approximation, heating is caused in varying amounts by the kinetic energy of the sputtered atoms, the latent heat of condensation of the sputtered atoms, and electron bombardment. The film temperature also depends on the optical emissivity of the deposited materials causing the temperature of films with higher emissivities such as Pd to remain significantly lower for comparable sputter times and power. For dc sputtering from an uncooled cathode, it was estimated that radiation from the cathode contributes significantly to the heating of the sputtered films.