Evolution of film temperature during magnetron sputtering

We report on the results of measurements of the temperature T-surf(F) which developed on the surface of films deposited by magnetron sputtering of chromium and copper targets on cooling and non-cooling silicon substrates. The T-surf(F) and substrate temperature (T-s) were simultaneously measured using high-resolution IR camera and thermocouple, respectively. We revealed that the T-surf(F) steeply grows, keeps constant when it achieves saturation level, and rapidly drops to the value of the T-s after stopping the deposition. At the same time, the T-s either does not change for the case of cooling substrate or increases to a certain level for noncooling substrate. However, in both cases the T-s remains several times lower than the T-surf(F). The T-surf(F) is proportional to the flux of energy delivered to the growth surface by sputtered atoms and other fast particles, weakly depends on the depositing metal and can achieve several hundreds of degrees C. This phenomenon is explained by a model assuming formation of a hot thin surface layer (HTSL) on the top of the growing film, which exists only during film deposition and exhibits extremely low thermal conductivity. Due to this unique property the temperature T-surf(F) of HTSL is several times higher than the T-s. Variations in the T-surf(F) fairly correlate with structure changes of Cr films along thickness investigated in detail previously. (c) 2006 American Vacuum Society.