TiN Metal Hard Mask Removal with Selectivity to Tungsten and TiN Liner

Abstract

Low-pH titanium nitride (TiN) removal formulations utilizing oxidizers other than hydrogen peroxide (H2O2) have been developed with superior TiN selectivity toward W and the inter-level dielectric (ILD) films. One critical challenge is protecting the TiN barrier layer between the W and dielectric layer, which is often exposed during the TiN metal hard mask (MHM) removal step. This study focused on developing and optimizing formulations with TiN MHM etch rates ≥ 100 Å/min at temperatures ≤ 60oC, with compatibility toward W, ILD films, and the TiN liner. The galvanic corrosion was tailored to protect the TiN liner in the presence of W. A simple yet novel patterned wafer test vehicle was developed to facilitate this work, enabling the investigation of the chemical impact at the W/TiN liner interface.