Atomic Layer Deposition of Platinum Thin Films

Abstract

Platinum thin films were grown at 300 °C by atomic layer deposition (ALD) using (methylcyclopentadienyl)trimethylplatinum (MeCpPtMe3) and oxygen as precursors. The films had excellent uniformity, low resistivity, and low-impurity contents. Structural studies by X-ray diffraction showed that the films were strongly (111) oriented. Growth rates of 0.45 Å cycle-1 were obtained with 4 s total cycle times. The film thickness was found to linearly depend on the number of the reaction cycles. Also, the possible reaction mechanism is discussed.

Remote Plasma ALD of Platinum and Platinum Oxide Films

“…Both processes resulted in smooth films and had generally lower root-mean-square roughness values ͑0.4-0.7 nm͒ than reported ͑0.75-4 nm͒. [1][2][3] Because island growth is known to promote surface roughening, 19 the fast nucleation and, consequently, more pronounced layer-by-layer growth can be related to the lower surface roughness obtained for the remote plasma ALD process.…”

“…Pt growth on these substrates could only be achieved by using a higher O 2 pressure ͑Ͼ0.8 mbar͒ as also typically used in the literature. 1,3 On the contrary, remote plasma ALD of Pt ͑0.5 s O 2 plasma͒ leads to immediate growth without a substantial nucleation delay. From the ellipsometry measurements, which have a reduced accuracy in the first 1-2 nm, it is concluded that growth per cycle is constant after the first 50 cycles.…”

“…The density and resistivity for these ϳ30 nm thick films are close to the bulk values of 21.4 g/cm 3 and 10.8 ⍀ cm, and they are similar to the values reported for thermal ALD of Pt. 1,3 The O and C contents remain below the RBS detection limit ͑Ͻ5%͒ and grazing incidence XRD spectra ͑Fig. 3͒ revealed a cubic phase composition for both the thermal and remote plasma ALD Pt films.…”

“…[1][2][3][4][5][6][7] While being less investigated, platinum oxide is of interest because of its optical properties and because PtO x can be ͑locally͒ reduced to Pt. [8][9][10] In the research efforts toward the applications of these films deposited by ALD, nucleation properties, material quality, and process temperature window are of key importance.…”

“…Few Pt ALD processes have been reported, of which the thermal ALD process using ͑methylcyclopentadienyl͒trimethylplatinum ͑MeCpPtMe 3 ͒ and O 2 gas described by Aaltonen et al 1 has become the most adopted. 2,3 This process relies on the dissociative chemisorption of O 2 on the Pt surface for oxidative decomposition of the precursor ligands.…”