Structural properties of BN thin films obtained by plasma‐enhanced chemical vapour deposition

Publisher Website
Google Scholar
Abstract
In this work BN films have been deposited by the plasma‐enhanced chemical vapour deposition (PECVD) technique on p‐type (100) silicon substrates, using borazine and nitrogen as precursors. X‐ray photoelectron spectroscopy, infrared spectroscopy, x‐ray diffraction, nuclear reaction analysis and Rutherford backscattering spectroscopy were used to analyse the films. The results of quantitative XPS analysis indicate the formation of a thin surface layer (∼3 nm) of boron oxynitride, BNO0.3, over a bulk of nearly stoichiometric boron nitride, BN1.1. The presence of the hexagonal phase mixed with amorphous boron nitride was identified. Infrared and Rutherford backscattering spectroscopies combined with a liquid etching technique were used to determine the composition and structure across the film thickness. From these measurements we infer that the composition across the film is nearly constant but with a gradual transition from an amorphous structure close to the Si/BN1.1 interface to an hexagonal structure towards the outer layers. Thermal treatments of the boron nitride films up to a temperature of ∼1000°C in a nitrogen atmosphere resulted in a small decrease of both the B/N atomic concentration ratio and the refractive index of the film. The insulating characteristics of the boron nitride for application as an intermetal dielectric were also treated. The electrical conduction results can be interpreted in terms of a Schottky mechanism, which allows us to calculate the high‐frequency dielectric constant, εr = 3.2.
Keywords