Conductivity Improvements of Atomic Layer Deposited Ta3N5

Abstract

Using TaCl5 as a precursor for thermal ALD of TaN results in an orthorhombic phase of Ta3N5 which is considered as a dielectric material. Conductivity of this film is found to depend on deposition and annealing temperature, which also modifies the X-ray diffraction spectrum. Both changes are induced by lowering the N:Ta ratio which adds new diffraction peaks. This modification is stronger when annealing is performed with TaN films covered by Al. This treatment makes Ta3N5 as attractive as metallic phase, δ-TaN to be used in work function metal stacks with Al contacts.