Multi-technique study of composition, structure, and bonding in PECVD amorphous silicon carbide films

Abstract

Amorphous semiconductor thin films are difficult to optimize for specific applications due to the high complexity of their chemical bonding structures, particularly for binary compounds like amorphous silicon carbide. Naturally, understanding the chemical composition and bonding is critical in determining the physical properties of the films. The chemical composition and bonding of various amorphous silicon carbide films are hereby studied using different analysis techniques: IBA technique (Ion Beam Analysis) which includes RBS (Rutherford Backscattering Spectrometry), ERDA (Elastic Recoil Detection Analysis) and NRA (Nuclear Reaction Analysis), as well as, time-of-flight Secondary Ion Mass Spectrometry (ToF-SIMS), X-Ray Photoelectron Spectroscopy (XPS), Raman spectroscopy, and Fourier Transform Infrared Spectroscopy (FTIR). The results from each technique, including atomic ratio determination and bonding/structural information, are compared in order to obtain a complete picture of the films’ structure. According to the deposition conditions, the films are found to contain Si-Si, Si-C, C-C, and oxygen-related bonds, with varying ordering including graphitic regions or nanocrystallinity. IBA techniques and XPS demonstrated high reliability, while Raman spectroscopy provided consistent results, except for films with a very high silicon content. TOF-SIMS and FTIR require empirical calibration based on known measurements to produce useable results.