Tailored waveform biasing for precise ion energy control during plasma-enhanced atomic layer deposition of nitrides

Ion energy control during plasma-enhanced atomic layer deposition (PEALD) allows for tailoring the properties of thin films. The energy of ions impacting the growth surface during plasma exposure can be controlled by applying a substrate bias, generally at a radio frequency (RF) of 13.56 MHz for PEALD. This approach, however, typically results in broad ion flux–energy distribution functions (IFEDFs) and can influence the plasma through changes in plasma density. Tailored waveform (TW) biasing provides an alternative, enabling narrow IFEDFs without affecting the plasma otherwise. In this Letter, TW biasing at 200 kHz was implemented during the PEALD of various metal nitrides, where a range of benefits was observed. TW biasing reduced oxygen incorporation in AlN films. For the conductive nitrides TaCxN1−x, WCxNy, TiN, and NbN, TW biasing led to significant improvements in electrical resistivity, with TaCxN1−x additionally showing enhanced crystallinity. More broadly, TW biasing during PEALD offers the potential for more controlled tuning of material properties compared to conventional RF biasing.