Arf Laser-Induced Chemical-Vapor Deposition of Tungsten for Gate Electrodes

Publisher Website
Google Scholar
Abstract
The deposition of W films by ArF laser-induced chemical-vapor deposition (LCVD) was investigated as a function of incident laser power, WF6 and H2 partial pressures, and substrate temperature. The deposition of W films by LCVD is discussed dividing that into two parts, thermal CVD (TCVD) and photon assisted CVD (PhCVD). The rate of PhCVD has been defined as the difference between the rates with and without laser irradiation. The reaction orders for PhCVD are 1, 0 with respect to WF6 and H2 partial pressures, respectively, and the rate linearly increases with increase in laser repetition rate. The activation energy in PhCVD is 0.17 eV. These facts indicate that, in LCVD, PhCVD takes place independently of TCVD and that the deposition rate in PhCVD is determined by the formation of F radicals in the dissociation of WF6 molecules by laser irradiation.MOS capacitors with LCVD-W gates were fabricated and their characteristics were compared with those with sputtered-W gates. It was shown that the level of contamination due to mobile ions in the capacitor with the LCVD-W gate was extremely low.