Copper films deposited by hot-wire CVD and direct liquid injection of CupraSelect

Copper films are deposited on Si substrates covered with W, TiN, and SiLK(R) using a novel CVD reactor in which reactions are assisted by a heated tungsten filament (hot-wire (HW)CVD). Liquid hexafluoroacetylacetonate Cu-I trimethylvinylsilane ((hfac) Cu-I (tmvs), CupraSelect(R)) is directly injected at room temperature into the reactor with the aid of a direct liquid injection system using N-2 as the carrier gas. The deposition rates of HWCVD Cu films obtained on W and TiN covered substrates are found to increase with filament temperature (65 and 170 degrees C are used). Moreover, high quality Cu films are deposited on SiLK(R), which cannot be done by conventional thermal CVD. Independent of the nature of the substrate, resistivities of HWCVD Cu films are higher than for thermally grown films due to carbon and oxygen contamination caused by the incomplete dissociation of the precursor. W impurities are detected in the HWCVD Cu films confined near the interface Cu film/substrate due to the presence of the filament. Their presence does not, however, degrade catastrophically the film conductivity.