Area-Selective Atomic Layer Deposition of TiN Using Aromatic Inhibitor Molecules for Metal/Dielectric Selectivity
Marc J. M. Merkx, Sander Vlaanderen, Tahsin Faraz, Marcel A. Verheijen, W. M. M. Kessels, Adriaan J. M. Mackus
Abstract
Despite the rapid increase in the number of newly developed processes, area-selective atomic layer deposition (ALD) of nitrides is largely unexplored. ALD of nitrides at low temperature is typically achieved by employing a plasma as the coreactant, which is not compatible with most approaches to area-selective ALD. In this work, a plasma-assisted ALD process for area-selective deposition of TiN was developed, which involves dosing of inhibitor molecules at the start of every ALD cycle. Aromatic molecules were identified as suitable inhibitor molecules for metal/dielectric selectivity because of their strong and selective adsorption on transition metal surfaces. A four-step (i.e., ABCD-type) ALD cycle was developed, which comprises aniline inhibitor (step A) and tetrakis(dimethylamino)titanium precursor (step B) dosing steps, followed by an Ar-H2 plasma exposure (step C), during which a substrate bias is applied in the second half of the plasma exposure (step D). This process was demonstrated to allow for ∼6 nm of selective TiN deposition on SiO2 and Al2O3 areas of a nanoscale pattern with Co and Ru non-growth areas. The TiN deposited using this ABCD-type process is of high quality in terms of resistivity (230 ± 30 μω cm) and impurity levels. This developed strategy for area-selective ALD of TiN can likely be extended to area-selective ALD of other nitrides.