Elimination of oxidized Mo by self-cleaning reaction with WF6 in the initial stages of selective W chemical-vapor deposition on Mo interconnections

Article abstract of DOI:10.1149/1.2069140

Selective W chemical vapor deposition (CVD) on Mo interconnections is studied to elucidate the surface cleaning mechanism in the initial stages of W CVD in a WF₆-H₂ gas system using ellipsometry, x-ray photoelectron spectroscopy, and Auger electron spectroscopy. Molybdenum oxide formed on the Mo interconnections during LSI fabrication processes is automatically removed by the reaction with WF₆ to form intermediates such as volatile molybdenumoxyfluorides, MoO_xF_y, following the chemical reaction: MoO₃ + 1/2 WF₆ → MoO₂F₂ + 1/2 WO₂F₃. This reaction exposes a Mo clean surface, and W deposition begins as soon as the oxide has been removed. From a contact-string test of two-layer interconnections, the contact resistivity with W-filled via holes on Mo interconnections is found to be lower than 3.3 × 10^-10 Ω-cm². This excellent contact characteristic is attributable to the surface cleaning effect on Mo by the reaction with WF₆.

Full text of DOI:10.1149/1.2069140

Downloaded on 2015-03-24 to IP 138.251.14.35 address. Redistribution subject to ECS terms of use (see ecsdl.org/site/terms_use) unless CC License in place (see abstract).

Downloaded on 2015-03-24 to IP 138.251.14.35 address. Redistribution subject to ECS terms of use (see ecsdl.org/site/terms_use) unless CC License in place (see abstract).

Downloaded on 2015-03-24 to IP 138.251.14.35 address. Redistribution subject to ECS terms of use (see ecsdl.org/site/terms_use) unless CC License in place (see abstract).

Downloaded on 2015-03-24 to IP 138.251.14.35 address. Redistribution subject to ECS terms of use (see ecsdl.org/site/terms_use) unless CC License in place (see abstract).

Downloaded on 2015-03-24 to IP 138.251.14.35 address. Redistribution subject to ECS terms of use (see ecsdl.org/site/terms_use) unless CC License in place (see abstract).