Microstructure of Copper Films Deposited on TiN Substrate by Metallorganic Chemical Vapor Deposition

The microstructure of copper films deposited on various TiN substrates by metallorganic chemical vapor deposition (MOCVD) from (hexafluoroacetylacetonate)Cu(I)(vinyltrimethylsilane) [ ( hfac ) Cu ( I ) (VTMS)] was studied. TiN films for copper barrier were formed by MOCVD on Si(100) at a deposition temperature of 250-350°C. The (200) plane in the TiN crystal is the preferred growth direction and as the roughness of the TiN film was increased, the growth direction was tilted away from the vertical direction to the substrate, which caused the crossover from the preferred growth direction to the 〈111〉 direction. On the other hand, for copper, (111) is the preferred direction and the crossover is to the 〈200〉 direction. The ratio of Cu(111)/Cu(200) was increased with the decrease of TiN(111)/TiN(200) ratio due to the influence of the tilted surface formed by the roughness of the TiN substrate. As the roughness of the TiN substrate increased, the roughness of the copper film also increased, but the grain size was not affected.