Spectrometric analysis of silicon nitride films deposited by low-temperature liquid-source CVD

Silicon nitride (SiN) films formed by liquid-source chemical vapor deposition (LSCVD) were analyzed for photonic applications. While this deposition technique for SiN has strengths in its low reaction temperature (>80 °C) and fast deposition rate (>50 nm/min), the material properties, such as...

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Bibliographic Details
Published in:Journal of applied physics 2019-10, Vol.126 (13)
Main Authors: Kou, R., Yamamoto, N., Fujii, G., Aihara, T., Tsuchizawa, T., Ishizawa, A., Hitachi, K., Gotoh, H., Ukibe, M., Yamada, K.
Format: Article
Language:English
Subjects:
Absorption spectra
Applied physics
Backscattering
Chemical bonds
Chemical composition
Chemical vapor deposition
Circuits
Ellipsometry
Fourier transforms
Hydrogen bonds
Infrared analysis
Low temperature
Material properties
Optical properties
Organic chemistry
Photonics
Refractivity
Scientific imaging
Silicon nitride
Spectrometry
Spectroscopy
Waveguides
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Summary:Silicon nitride (SiN) films formed by liquid-source chemical vapor deposition (LSCVD) were analyzed for photonic applications. While this deposition technique for SiN has strengths in its low reaction temperature (>80 °C) and fast deposition rate (>50 nm/min), the material properties, such as its composition, chemical bond, and optical absorption bands in waveguides, have not been studied quantitatively. Hence, we probed SiN films to understand the material characteristics by ultraviolet-to-midinfrared ellipsometry, on-chip waveguide absorption spectrometry, Rutherford backscattering/hydrogen forward-scattering spectrometry, and Fourier-transform infrared spectrometry. As interpreted by a combination of the series of analyses, the N–H bond concentration of higher than 1021 cm−3 leaves an absorption notch (>6.5 dB/cm) at a wavelength of 1550 nm, which cannot be avoided even by systematically varying the deposition conditions. However, except for that absorption range, a low-loss SiN waveguide (0.5–1.0 dB/cm) with a practically applicable high refractive index (∼1.85) can be formed at the deposition temperature of 100 °C. This basic materials research, which combines multiple spectrometric analyses, will help to improve our understanding of a LSCVD SiN film for photonics circuit integration.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.5114675