Optical properties of plasma-enhanced chemical vapor deposited SiCxNy films by using silazane precursors

Wei Yuan Chang, Chieh Yu Chang, Leu-Jih Perng*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

In this study, amorphous silicon carbonitride (SiCxNy) films were fabricated by radio frequency (RF) chemical vapor deposition (PECVD) using a single silazane precursor and a low power density (0.15 W/cm3) for better compositional control. The effects of the precursor chemical structure (C/Si ratio, C–Si–N structure, and vinyl groups) and deposition temperature (Ts) on the chemical structure and optical properties of SiCxNy films were examined using Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. Specifically, two new single precursors; namely, n-methyl-aza-2,2,4-trimethylsilacyclopentane (MTSCP) and 1,3-divinyl-1,1,3,3-tetramethyl-disilazane (DVTMDS) were studied and compared. SiCxNy films deposited using MTSCP involving Si–C3–N rings formed Si–N and Si–(CH2)3– crosslinked structures at Ts ≤ 100 °C, and were then changed to predominantly Si–CH2–N–Si crosslinked structures at Ts > 300 °C, leading to a wide range of optical band gap from 5.2 to 3.7 eV. Compared to DVTMDS-deposited SiCxNy films, their relatively higher percentage of Si–C–N structure accounted for the lower optical band gap and reduced transmission. DVTMDS with di-vinyl groups readily formed a Si–(CH2)2– bridge in SiCxNy films Ts ≤ 200 °C, resulting in excellent optical transmittance. The transmittance in the visible wavelengths of 400 °C-deposited SiCxNy film using DVTMDS still showed 85%. Also, tunable refractive index between 1.44 and 2.10 were obtained for SiCxNy films deposited at Ts ≤ 400 °C.

Original languageEnglish
Pages (from-to)671-679
Number of pages9
JournalThin Solid Films
Volume636
DOIs
StatePublished - 31 Aug 2017

Keywords

  • Optical band gap
  • Optical properties
  • PECVD
  • Silazane precursor
  • Silicon carbonitride films
  • Transmittance

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