Atomic layer deposition of LiF using LiN(SiMe3)2 and SF6 plasma
N Hornsveld1, W M M Kessels, R A Synowicki
1Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands. n.hornsveld@tue.nl.
Physical Chemistry Chemical Physics : PCCP
|April 22, 2021
Summary
This study introduces a new atomic layer deposition (ALD) method for lithium fluoride (LiF) films using a novel precursor and sulfur hexafluoride (SF6) plasma. Short plasma exposures yield high-purity LiF films with desirable optical properties.
Area of Science:
- Materials Science
- Thin Film Deposition
- Plasma Chemistry
Background:
- Atomic Layer Deposition (ALD) is crucial for precise thin film fabrication.
- Lithium fluoride (LiF) is a key material in various optical and electronic applications.
- Developing novel ALD processes for high-purity LiF is an ongoing research area.
Purpose of the Study:
- To develop a new atomic layer deposition (ALD) route for lithium fluoride (LiF) films.
- To investigate the use of LiN(SiMe3)2 precursor and SF6 plasma.
- To characterize the properties and purity of the deposited LiF films.
Main Methods:
- Atomic Layer Deposition (ALD) using LiN(SiMe3)2 and SF6 plasma.
- Characterization using spectroscopic ellipsometry and mass spectrometry.
- Optimization of plasma conditions (exposure time, pressure, power).
Main Results:
- Conformal, polycrystalline LiF films deposited at 150 °C with a growth rate of ~0.4 Å/cycle.
- Films were slightly lithium-rich (LiF0.8) with low impurity levels (<1 at%).
- Refractive index of 1.37 at 633 nm; short plasma exposures preferred for optical properties.
Conclusions:
- SF6 plasma is a viable coreactant for ALD of LiF.
- The new ALD route offers a promising alternative for high-purity LiF film synthesis.
- Understanding plasma-surface interactions is key to optimizing ALD processes.
