Atomic Layer Deposition of Tantalum Nitride on Organosilicate and Organic Polymerbased Low Dielectric Constant Materials

Abstract

AbstractA previously developed metal-organic atomic layer deposition (ALD) tantalum nitride (TaNx) process was employed to investigate the growth of TaNx liners on low dielectric constant (low-k) materials for liner applications in advanced Cu/low-k interconnect metallization schemes. ALD of TaNx was performed at a substrate temperature of 250°C by alternately exposing low-k materials to tertbutylimido-tris(diethylamido)tantalum (TBTDET) and ammonia (NH3), separated by argon purge steps. The dependence of TaNx film thickness on the number of ALD cycles performed on both organosilicate and organic polymer-based low-k materials was determined and compared to baseline growth characteristics of ALD TaNx on SiO2. In order to assess the effect of the deposition of TaNx on surface roughness, atomic force microscopy (AFM) measurements were carried out prior to and after the deposition of TaNx on the low-k materials. The stability of the interface between TaNx and the low-k materials after thermal annealing at 350°C for 30 minutes was studied by examining interfacial roughness profiles using cross-sectional imaging in a high-resolution transmission electron microscope (HR-TEM). The wetting and adhesion properties of Cu/low-k were quantified using a solid-state wetting experimental methodology after integration of ALD TaNx liners with Cu and low-k dielectrics.