| AVS 64th International Symposium & Exhibition | |
| Plasma Science and Technology Division | Thursday Sessions |
| Session PS+TF-ThA |
| Session: | Plasma Enhanced ALD |
| Presenter: | Tahsin Faraz, Eindhoven University of Technology, Netherlands |
| Authors: | T. Faraz, Eindhoven University of Technology, Netherlands H.C.M. Knoops, Oxford Instruments Plasma Technology, UK S. Karwal, Eindhoven University of Technology, Netherlands M.A. Verheijen, Eindhoven University of Technology, Netherlands A.A. van Helvoirt, Eindhoven University of Technology, Netherlands D.M. Hausmann, Lam Research Corporation J. Henri, Lam Research Corporation M. Creatore, Eindhoven University of Technology, Netherlands W.M.M. Kessels, Eindhoven University of Technology, Netherlands |
| Correspondent: | Click to Email |
Recently, it has been shown that the ion energy can play a significant role on the physical and chemical properties of thin films grown using plasma-enhanced atomic layer deposition (PEALD).1 In this work, we demonstrate the impact of ion energy control during PEALD of transition metal nitrides (e.g., TiNx, HfNx, etc.) which are of great interest for nanoelectronic device applications owing to their low electrical resistivity and excellent diffusion barrier properties.2 Ion energy control during plasma exposure was carried out in a commercial 200 mm remote plasma ALD system (Oxford Instruments FlexAL) equipped with radio-frequency (RF) substrate biasing (13.56 MHz, up to 100 W power, -350 V resulting DC bias voltage). In such low pressure, remote inductively-coupled-plasma reactors, the ion energy can be controlled independently of the ion flux by applying an RF bias signal on the substrate table during the plasma exposure step.
Depositions performed under no bias conditions for TiNx (at 200°C) and HfNx (at 450°C) films using a 10 s H2 (+Ar) plasma yielded electrical resistivities of 1960±60 and (900±0.7)x103 μΩcm and mass densities of 3.8±0.2 and 10.1±0.2 g/cm3, respectively. Enhancing ion energies with substrate biasing during PEALD was observed to have pronounced effects on the chemical composition, microstructure and material properties of these transition metal nitrides. Energetic ion bombardment through application of bias voltages lowered film resistivity by one order of magnitude for TiNx (139±10 μΩcm at -187V bias) and by two orders of magnitude for HfNx ((330±70)x101 μΩcm at -130V bias) while also increasing their respective mass densities (4.9±0.2 and 10.5±0.2 g/cm3). The residual stress of these films were also observed to change from tensile under no bias to compressive under bias conditions. The oxygen impurity content for films deposited without substrate biasing (~20 to 30%) was observed to be significantly reduced (≤ 4%) in films grown with bias voltages applied during plasma exposure. Furthermore, it will be discussed how the use of substrate biasing enhances PEALD process capability by providing several additional knobs (magnitude, duration and duty-cycle of bias, etc.) for tuning a wide range of material properties.
1 Profijt et al., J. Vac. Sci. Technol. A, 31, 01A106 (2013)
2 Karwal et al., J. Vac. Sci. Technol. A, 35, 01B129 (2017)