Measurement of hydrogen content in diamond like carbon thin films by ERDA

Abstract

The hydrogen content in diamond like carbon (DLC) thin films has been determined by elastic recoil detection analysis (ERDA) using a 2.7 MeV He 2+ beam. The DLC films were prepared by an electron cyclotron resonance (ECR) microwave plasma chemical vapor deposition (CVD) system. Analysis of the spectra obtained reveals a uniform 29% concentration of hydrogen in the sub-surface region. Increasing the substrate temperature from room temperature to 250°C resulted in a decrease to 23% of the hydrogen concentration, accompanied by a 2.4 times increase of the film's Knoop hardness. This clearly demonstrates the usefulness of the hydrogen concentration measurement in monitoring changes in the film properties. We also discuss other factors during deposition such as bias voltage, microwave power, etc., which influences the hydrogen contents in the DLC film.