MOCVD of Platinum Films from (CH3)3CH3CpPt and Pt(acac)2: Nanostructure, Conformality, and Electrical Resistivity†

A potentially manufacturable liquid-source MOCVD process was applied to deposit platinum (Pt) films (12-140 nm) on thermally oxidized Si substrates. The deposition of Pt films was carried out at a substrate temperature of 350°C by oxygen-assisted pyrolysis of complex precursors in a low-pressure, hot-wall reactor. The effects of two different metal-organic precursors, a) trimethyl methyl cyclopentadienyl platinum [(CH 3 ) 3 CH 3 CpPt], and b) platinum acetylacetonate [Pt(acac) 2 ], on the properties of Pt films were studied. Although the polycrystalline Pt films deposited from Pt(acac) 2 exhibited a preferred (111) orientation with a X-ray intensity ratio of I (111) /I (200) =40, the films deposited from (CH 3 ) 3 CH 3 CpPt were highly (111) oriented with I (111) /I (200) = 270. The following properties were typical of Pt films from Pt(acac) 2 as compared to Pt films from (CH 3 ) 3 CH 3 CpPt: finer grain size (25 nm vs. 50 nm), smaller root mean square (rms) surface roughness (5 nm vs. 15 nm), and better step coverage (95 % vs. 35 %). These experimental findings indicated that growth of Pt films from Pt(acac) 2 occurred under the kinetically-limited regime, whereas the deposition of Pt from (CH 3 ) 3 CH 3 CpPt was limited by the mass transport rate. Additionally, the temperature (4.2-293 K) dependence of the electrical resistivities (p) of Pt films was measured and the electron mean free paths were estimated. It was observed that ρ(T) deviated from Matthiessen's rule.