| AVS 63rd International Symposium & Exhibition | |
| Applied Surface Science | Thursday Sessions |
| Session AS+SS-ThM |
| Session: | Depth Profiling, Buried Interfaces, and 3D Analyses |
| Presenter: | Riikka Puurunen, VTT Technical Research Centre of Finland |
| Authors: | R.L. Puurunen, VTT Technical Research Centre of Finland J. Dendooven, Ghent University, Belgium V. Cremers, Ghent University, Belgium C. Detavernier, Ghent University, Belgium |
| Correspondent: | Click to Email |
High conformality—the ability of a thin film to cover a complex three-dimensional substrate uniformly—is a key advantage of atomic layer deposition (ALD) compared to chemical vapor deposition (CVD) and physical vapor deposition (PVD) processes. More than 700 ALD processes (with unique reactant pairs/activation) have been reported, as calculated from Ref. [1]. Conformality has been experimentally studied for a small minority of these, most likely because of the lack of easily available test structures and accessible methods of analysis.
When conformality is investigated, most typically, vertical trenches (or holes) etched into silicon, typically with aspect ratio (AR) up to around 50:1, are used and the results are analysed point by point by cross-sectional electron microscopy. Comparison of results obtained in different studies is difficult because of the lack of standard test structures and standard means of analysis, and the large variety of process conditions that are used. The theoretical framework for interpreting the conformality results is also underdeveloped.
To develop the conformality analysis, we have reported on macroscopic [2, 3] and microscopic [4] lateral high aspect ratio (LHAR) test structures. In contrast to vertical HAR, LHAR structures allow one to investigate thin film thickness and properties in very demanding aspect ratios (>10 000:1) and obtain accurate information of film thickness and properties along the feature by standard means of measurement such as ellipsometry and reflectometry. The purpose of the present work is to compare results obtained for different thin film processes in different test structures (our own + literature) using the highly studied [1, 5] Me3Al/H2O ALD process as baseline. We propose a classification scheme for how the thickness line profiles are expected to vary inside LHAR structures in different cases of characteristic governing growth chemistries.
Acknowledgements: This work has been funded by the Finnish Centre of Excellence in Atomic Layer Deposition, BOF-UGent, FWO-Vlaanderen and SIM-Flanders (TRAP-FUNC project). Feng Gao and Meeri Partanen are thanked for fabricating the microscopic LHAR structures.
References:
[1] V. Miikkulainen et al., J. Appl. Phys. 113 (2013) 021301.
[2] J. Dendooven et al., J. Electrochem. Soc. 156 (2009) P63.
[3] J. Dendooven et al., J. Electrochem. Soc. 157 ( 2010), G111.
[4] F. Gao et al., J. Vac. Sci. Technol. A, 33 (2015), 010601.
[5] R. L. Puurunen, J. Appl. Phys. 97 (2005) 121301.