MOCVD of palladium films: kinetic aspects and film properties

Palladium (Pd), a well-known catalytic material, is used in many hydrogenation reactions in the chemical industry. The method of catalyst preparation strongly affects its catalytic activity. The MOCVD technique is more expensive compared to the classical wet impregnation. However, a great advantage of this method is deposition of small amounts of catalysts finely dispersed on the outer and inner surface of the support. It has been shown that by using this technique, the same catalytic activity can be reached with smaller mass fraction of catalytic substance. Small crystals and finely dispersed Pd can be obtained by MOCVD already at 220 °C at ambient or reduced pressure. A hot-wall reactor system was used to deposit Pd from a mixture of (1,1,1,5,5,5)-hexafluoro-2,4-pentanedionato-palladium [Pd(hfac)2] in helium as a carrier gas. The present work shows some kinetic aspects of the Pd MOCVD process and a simplified kinetic model is proposed. The deposition rate is investigated and discussed for different Pd(hfac)2 concentrations, deposition temperatures, pressures and deposition time. The prepared Pd films are characterized by SEM and AES.