Novel technology of high-aspect-ratio etch utilizing coverage-controllable atomic layer deposition

Abstract

We demonstrated a coverage-controllable sidewall protective film by controlling the degree of oxidation during plasma-enhanced SiO2 atomic layer deposition (ALD) as a novel technology to suppress bowing in a high-aspect-ratio-contact (HARC) hole etch process. By depositing SiO2 protective film with atomic order on only the top-local region of patterns, to suppress bowing was achieved during HARC etch without the shrinkage of the bottom critical dimension (CD) and etch-stop. In addition, we investigated the parameters that determine the ALD coverage to estimate the coverage profile of sidewall protective film. By analyzing the relationship between activation time and ALD film thickness at each AR, we confirmed that the coverage is determined by the transport of oxygen radical based on the Knudsen transport model. Furthermore, we developed an ALD simulator from the transport model, and successfully estimated the coverage of protective film during etching to improve the verticality of the HARC profile with small bowing-bottom CD bias.