Area-Selective Atomic Layer Deposition of TiN Using Aromatic Inhibitor Molecules for Metal/Dielectric Selectivity

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.