DIMETHYLPALLADIUM(II) COMPLEXES AS PRECURSORS FOR CHEMICAL-VAPOR-DEPOSITION OF PALLADIUM

Dimethylpalladium(II) complexes, cis-[PdMe2(PR3)2] (R = Me and Et) and [PdMe2(tmeda)] (tmeda = N,N,N',N'-tetramethylethylenediamine), were s tudied as precursors for low-temperature chemical vapor deposition (CV D) of thin films of palladium. All three precursors gave mirrorlike pa lladium films at substrate temperatures of 130-300-degrees-C, using re duced pressure CVD. The films prepared by the simple thermal CVD proce ss contained carbon impurities (ca. 10%) and a study by XANES and EXAF S indicates that the Pd-Pd distances are longer than in a pure palladi um film. Typical film resistivities were 10(-4) OMEGA cm for films of 0.5 mum thickness. For the phosphine-containing precursors, cis-[PdMe2 (PR3)2], CVD In the presence of hydrogen gave films which were essenti ally free of carbon impurities but which contained significant phospho rus impurity. Palladium films deposited from [PdMe2-(tmeda)] gave a mu ch smoother surface than that from cis-[PdMe2(PMe3)2] under the same C VD conditions. The thermal properties of the precursors were also stud ied in both the gas phase and condensed phase. Methane, ethane and eth ylene were observed as volatile products of the CVD processes, and the product ratio was strongly dependent on the properties of the donor l igand. Methane was mainly formed by hydrogen reduction, ethane is the result of a simple intramolecular reductive elimination, and the signi ficant amount of ethylene obtained on thermolysis of cis-[PdMe2(PEt3)2 ] is derived from the Et3P ligands.