The effect of deposition temperature and boron addition in Ti–B–C–N films deposited by plasma-enhanced chemical vapor deposition

Quaternary Ti–B–C–N films were synthesized on AISI 304 stainless steel and Si wafer by a PECVD technique using a gaseous mixture of TiCl4, BCl3, CH4, Ar, N2, and H2. The microstructure and micro-hardness of the films were largely affected by the deposition temperature and boron content. As the temperature increased from 370 °C, the micro-hardness of the film steeply increased due to the enhanced crystallinity of the film and reached to the maximum value of 42 GPa at 570 °C. However, the hardness decreased again at higher temperatures above 570 °C due to the enlarged grain size. The boron addition into Ti–C–N film resulted in the microstructural modification and our quaternary Ti–B(9 at.%)–C–N film had a fine composite microstructure consisting of nano-sized Ti(C,N) crystallites surrounded by amorphous phase of BN. The micro-hardness of Ti–B–C–N film increased from ∼21 GPa of Ti–C–N film up to ∼42 GPa of Ti–B(9 at.%)–C–N one. In this work, a systematic investigation of the microstructure and micro-hardness of Ti–B–C–N films were conducted at the deposition conditions of various temperatures and boron contents through the instrumental analyses.