Area selective deposition of TiO ₂ by intercalation of plasma etching cycles in PEALD process: A bottom up approach for the simplification of 3D integration scheme

A selective deposition process for bottom-up approach was developed in a modified plasma enhanced atomic layer deposition (PEALD) sequence. As a case study, a very standard PEALD TiO ₂ using organo-amine precursor and O ₂ plasma is chosen. The metal oxide selectivity is obtained on TiN versus Si-based surfaces by adding one etching/passivation plasma step of fluorine every n cycles in a PEALD-TiO ₂ process. Fluorine gas NF ₃ allows (1) to etch the TiO ₂ layer on Si, SiO ₂ , or SiN surface while keeping few nanometers of TiO ₂ on the TiN substrate and (2) to increase the incubation time on the Si-based surface. Quasi-in situ XPS measurements were used to study the incubation time between Si/SiO ₂ substrates versus TiN substrate. Results show that Si-F bonds are formed on Si and lock the surface reactions. The effectiveness of this atomic layer selective deposition method was successfully tested on a 3D patterned substrate with the metal oxide deposited only at the edge of metal lines.