Reductive Transformation of ALD TeO2 into Continuous and Impurity-Free Tellurium Films

Abstract

The lack of high-performance p-type channel materials that can be processed at low temperatures has hindered the progress of monolithic 3D integration. Despite its high hole mobility, Te often exhibits discontinuous island-like growth when deposited using atomic layer deposition (ALD) due to its weak surface interactions. This study introduces a new reductive transformation method that addresses this inherent issue by converting continuous ALD-grown TeO2 films into crystalline, impurity-free Te layers. Notably, this approach allows for the formation of fully continuous Te films, even at thicknesses below approximately 5 nm. By utilizing a TeH2-assisted reduction pathway generated in situ, this self-limiting process ensures complete removal of oxygen from both the bulk and interface regions while preserving exceptional conformality in structures with high aspect ratios. The resulting Te films exhibit excellent electrical properties, such as low contact resistance and stable switching in nonplanar transistor configurations. By decoupling the film continuity from surface wettability, this chemical transformation approach provides a breakthrough solution for integrating ultrathin p-type chalcogenides into advanced back-end-of-line architectures.