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Area-Selective Atomic Layer Deposition through Selective Passivation of SiO2 with a SF6/H2 Plasma
Olaf C A Bolkenbaas1, Marc J M Merkx1, Nicholas J Chittock1,2
1Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
Chemistry of Materials : a Publication of the American Chemical Society
|July 28, 2025
Summary
Area-selective atomic layer deposition (ALD) selectively deposits titanium dioxide (TiO2) on various materials by chemically passivating silicon dioxide (SiO2) with a plasma pretreatment, enabling advanced semiconductor manufacturing.
Area of Science:
- Materials Science
- Chemical Engineering
- Semiconductor Manufacturing
Background:
- Area-selective atomic layer deposition (ALD) is crucial for advanced semiconductor fabrication.
- Developing selective deposition methods is key to creating more powerful and efficient electronic devices.
Purpose of the Study:
- To develop a chemical passivation method for area-selective deposition of titanium dioxide (TiO2).
- To investigate the selective deposition of TiO2 on different substrates (ZnO, HfO2, Al2O3) while preventing growth on SiO2.
Main Methods:
- Utilized a SF6/H2/Ar plasma pretreatment to passivate SiO2 surfaces.
- Employed tetrakis-(dimethylamido)-titanium (TDMAT) and H2O for TiO2 ALD.
- Optimized the SF6/(H2 + SF6) flow ratio and substrate temperature (150 °C).
- Analyzed surface chemistry using in-situ reflection absorption infrared spectroscopy (RAIRS) and density functional theory (DFT) calculations.
Main Results:
- Achieved selective TiO2 deposition with 90% selectivity on HfO2, Al2O3, and ZnO.
- Minimized SiO2 etching (<1 Å) with a SF6/(SF6 + H2) ratio of 0.24.
- Observed replacement of Si-OH and Si-H groups with Si-F groups on SiO2, indicating effective passivation.
- Confirmed precursor reaction on fluorinated Al2O3 but unfavorable reaction on F-terminated SiO2.
Conclusions:
- A SF6/H2/Ar plasma pretreatment effectively passivates SiO2, enabling area-selective TiO2 ALD.
- Optimized plasma conditions maximize TiO2 nucleation delay on SiO2 while allowing deposition on other materials.
- This approach offers a promising route for future area-selective deposition processes in semiconductor manufacturing.
