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 [(CH3)3CH3CpPt], 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 (CH3)3CH3CpPt 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 (CH3)3CH3CpPt: 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 (CH3)3CH3CpPt was limited by the mass transport rate. Additionally, the temperature (4.2–293 K) dependence of the electrical resistivities (ρ) of Pt films was measured and the electron mean free paths were estimated. It was observed that ρ(T) deviated from Matthiessen's rule. Platinum thin films are grown on thermal‐SiO2/Si at 350 °C from (CH3)3‐CH3CpPt and Pt(acac)2. Films deposited from the first precursor show an orientation ratio of [I(111)/I(200) = 270], a large grain size of 50 nm, and poor conformality of 35–45 %, while those produced from Pt(acac)2 show [I(111)/I(200) = 40], finer grain structure, and excellent conformality of 85–95 % (see Figure). Film resistivity exhibits values of 23.6 and 27.6 μΩ cm.