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

Abstract

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 (r) of Pt films was measured and the electron mean free paths were estimated. It was observed that r(T) deviated from Matthiessen's rule.

Platinum Protective Coatings Processed by Organometallic CVD

“…[13] The lower growth rate observed at high temperature was attributed to a precursor depletion in the bond layer. [9] However, this…”

“…The high efficiency of deposition in reducing conditions; i.e., using H 2 as the reacting gas, has been previously reported. [2,6,9] This is attributed to the autocatalytic character of Pt deposition from Me 3 (MeCp)Pt. The observed incubation time confirms this explanation; when the slowly growing platinum clusters reach a critical size, the catalytic effect of platinum becomes effective, leading to rapid decomposition of the adsorbed precursor.…”

“…[12] The preferential (111) orientation of Pt films grown from Me 3 (MeCp)Pt has been reported in many studies. [2,9,[14][15][16][17] It was observed that on monocrystalline substrates, or on substrates with which the Pt film is strongly bonded, platinum crystallites are randomly, or even (200) oriented. [17] In contrast, Pt films present a (111) orientation when there is a lack of cohesion with or adhesion to the substrate.…”

Optically Transparent, Ultrathin Pt Films as Versatile Metal Substrates for Molecular Optoelectronics

“…A comparison can be made only with thicker Pt films of an analogous polycrystalline Pt(111) structure, which generally exhibits a higher roughness. [16,22] Thermal treatment on the AP films is also accompanied by a substantial improvement in their chemical and mechanical robustness. In fact, A and F Pt films subjected to chemical and mechanical stresses under conditions exceeding those typically used during the preparation of SAMs on noble metals remain essentially unaltered.…”

Effects of Thermal Annealing on Pt-Shell/MgO-Core Nanowires

“…[3][4][5][6][7] In the present study, we have fabricated the coaxial nanowires, in which MgO core nanowires were surrounded by platinum (Pt) shell layers. Pt has a low electrical resistivity, high chemical inertness, and thermal stability with its melting point of 1769 C. 8 Pt nanostructures are of interest for a great variety of potential applications, including catalysts in many industrial processes, [9][10][11][12][13][14] biosensors, 15 gas sensors, 16 fuel cells, 17 and nanowire-based electronic devices. 18 Also, MgO has been considered to be promising material for many applications, such as catalysis, superconductor products, and optoelectronics.…”