AVS 66th International Symposium & Exhibition
    Thin Films Division Monday Sessions
       Session TF+2D+AP+EL+SS-MoA

Invited Paper TF+2D+AP+EL+SS-MoA8
Real-time Monitoring of the Surface Chemistry of Atomic Layer Deposition by Ambient Pressure X-ray Photoelectron Spectroscopy

Monday, October 21, 2019, 4:00 pm, Room A124-125

Session: ALD and CVD: Nucleation, Surface Reactions, Mechanisms, and Kinetics
Presenter: Joachim Schnadt, Lund University, Sweden
Authors: J. Schnadt, Lund University, Sweden
P. Shayesteh, Lund University, Sweden
R. Tsyshevskiy, University of Maryland
J.-J. Jean-Jacques, Sorbonne Université, France
F. Bournel, Sorbonne Université, France
R. Timm, Lund University, Sweden
A.R. Head, Brookhaven National Laboratory
G. D'Acunto, Lund University, Sweden
F. Rehman, Lund University, Sweden
S. Chaudhary, Lund University, Sweden
R. Sánchez-de-Armas, Uppsala University, Sweden
F. Rochet, Sorbonne Université, France
B. Brena, Uppsala University, Sweden
A. Mikkelsen, Lund University, Sweden
S. Urpelainen, Lund University, Sweden
A. Troian, Lund University, Sweden
S. Yngman, Lund University, Sweden
J. Knudsen, Lund University, Sweden
Correspondent: Click to Email
Atomic layer deposition (ALD) and chemical vapour deposition (CVD) are very important methods that enable a highly controlled growth of thin films [1]. The surface chemis­try of the underlying processes remains, however, little understood. While idealised reac­tion mechanisms have been developed, they represent postulates rather than models based on the factual identification of surface species and kinetics [2]. New in situ and operando methods offer the prospect of gaining a much more thorough understanding of the involved molecular and atomic surface processes and (dynamic) structures, which, in turn, means that a much better knowledge basis can be achieved for the future improvement of materials and growth recipes (see, e.g. [3,4]). One such operando method, which can be applied to the investigation of ALD and CVD, is synchrotron-based ambient pressure x-ray photoelectron spectroscopy (APXPS). While conventional x-ray photoelectron spectroscopy (XPS) is limited to vacuum pressures of 10-5 mbar and below, APXPS can be carried out at realistic pressure. Today, most APXPS machines can operate at pressures up to the 10 mbar regime, which is an ideal match to the pressure regime used in standard ALD reactors.

Here, I will report on our recent efforts to apply density functional theory (DFT)-assisted synchrotron-based APXPS to the ALD/CVD of oxides (TiO2, SiO2, and HfO2) on semiconductor (InAs and Si) and oxide surfaces (TiO2, RuO2) [3-5]. I will show that APXPS allows the identification of the surface species occurring during thin film growth and the real-time monitoring of their evolution with a time resolution of down into the millisecond regime. Here, DFT is an important tool for pinpointing the nature of the chemical species and for providing deeper insight in the surface chemical processes. I will also report on our efforts to further improve instrumentation with the goal of achieving a much closer match of the APXPS sample environment with the geometries used in conventional ALD reactors. The development will also open for the use of a wider range of precursors and growth protocols.

[1] V. Miikkulainen et al., J. Appl. Phys. 113 (2013) 021301.

[2] F. Zaera, Coord. Chem. Rev. 257 (2013) 3177.

[3] B. A. Sperling et al. Appl. Spectrosc. 67 (2013) 1003.

[4] K. Devloo-Casier et al., J. Vac. Sci. Technol. 32 (2014) 010801.

[3] S. Chaudhary et al. , J. Phys. Chem. C 119 (2015) 19149.

[4] A. R. Head et al. , J. Phys. Chem. C 120 (2016) 243.

[5] R. Timm et al., Nature Commun. 9 (2018) 412.