Hot-wire assisted chemical vapor deposition of Cu by direct-liquid-injection of CupraSelect®

Abstract

A novel chemical vapor deposition reactor for Cu films is presented in which the chemical reactions were assisted by a heated tungsten filament (hot-wire CVD, HWCVD). The vapors used were hexafluoroacetylacetonate Cu(I) trimethylvinylsilane (CupraSelect®), which is liquid at room temperature and was injected into the reactor with the aid of a direct-liquid injection system using N 2 as carrier gas. The deposition rates of HWCVD Cu films obtained with this reactor were one and a half times higher than for typical thermally grown films at a filament temperature of 170 °C. Moreover, high quality Cu films were deposited on SiLK®, which cannot be done by thermal CVD. The resistivity of HWCVD Cu films is two to five times higher than those for thermally grown films due to the possible presence of impurities into the Cu films. The reaction of the CupraSelect® vapors with the W filament and the W-covered Si substrate, leads to the formation of Cu–W–O compounds in the Cu films. The presence of such compounds does not degrade catastrophically the conductivity of Cu HWCVD films.