Effect of voltage on diamond-like carbon thin film using linear ion source

Diamond-like carbon (DLC) films were deposited by the linear ion source (LIS)-physical vapor deposition condition changing the anode voltages from 800 V to 1800 V and bias voltages from 0 V to − 200 V and characteristics of the films were investigated using Nano-indentation, Micro Raman spectroscopy, Field Emission-Scanning Electron Microscope (FE-SEM), Residual stress tester, Time-of-Flight Secondary Ion Mass Spectroscopy (TOF-SIMS) and X-ray Photoelectron Spectroscopy (XPS). The residual stress and hardness increased relatively with increasing the ion energy up to anode voltage of 1400 V and − 100 bias voltage respectively. From the Micro Raman analysis, the content of sp3 carbon in sp3/sp2 ratio was increased with increasing the anode voltage. From these results, residual stress and hardness of DLC films are increased as increase of anode voltages due to the enhancement of 3-dimensional cross-links between carbon atoms and dangling bond. Also, the internal compressive stress is increased with increasing the voltages. Therefore, the optimum anode and bias voltage are considered to be around 1400 V and − 100 V respectively in these experimental conditions.

► DLC films were deposited by linear ion source — PVD method.
► sp3 bond is maximum at anode voltage above 1400 V and bias voltage of − 100 V.
► DLC film hydrogen contents were 37 at.%, and the hardness was 23 GPa.
► The optimum anode voltage and bias voltage for DLC deposition are 1400 V and − 100 V, respectively.