Combining Experimental and DFT Investigation of the Mechanism Involved in Thermal Etching of Titanium Nitride Using Alternate Exposures of NbF₅and CCl₄, or CCl₄Only

Thermally activated chemical vapor-phase etching of titanium nitride (TiN) is studied by utilizing either alternate exposures niobium pentafluoride (NbF5) and carbon tetrachloride (CCl4) or using CCl4 alone. Nitrogen (N2) gas purge steps are carried out in between every reactant exposure. Titanium etched a non-self-limiting way NbF5–CCl4 based binary chemistry at temperatures 370 460 °C. Spectroscopic ellipsometry weight balance used to calculate the etch per cycle. For chemistry, an cycle ?0.8 Å obtained for 0.5 3 s long NbF5 CCl4, respectively On contrary, under same conditions, process with alone gives about Å. In CCl4-only process, thickness TiN films removed °C varies linearly number cycles. Furthermore, able selectively over other materials such as Al2O3, SiO2, Si3N4. X-ray photoelectron spectroscopy bright field transmission electron microscopy studying post-etch surfaces. To understand possible reaction products energetics, first-principles calculations density functional theory. From thermochemical analysis models, it found that cannot while can high temperatures. The predicted byproducts molecules surface TiCl3 ClCN. Similarly, TiF4, NbFCl3, ClCN be likely when exposed both CCl4. A more favorable (?G = ?2.7 eV 640 K) compared exposure only ?2 process. This indicates enhanced rate alternately which close agreement experimental results.