Carrier gas effects on the selectivity in chemical vapor deposition of copper

One of the interesting areas of Cu-CVD is the selective deposition, which attracts more attention based on its potential as a patterning method of Cu. The selectivity of Cu-CVD for PECVD-SiO₂, TiN, and Al substrates was investigated systematically using a (hfac)Cu(VTMS) with carrier gas of H₂ and Ar as functions of deposition temperatures (150-200°C), chamber pressures (0.3-1.0 Torr), and deposition times. The apparent incubation time on each substrate was increased as the conductivity of substrates, the deposition temperature, and the chamber pressure were decreased. Moreover, H₂ carrier gas atmosphere had shorter incubation time, higher deposition rate, and smaller, better-connected Cu grains than Ar carrier gas. These are considered to be due to the increment of surface adsorption sites (-OH) of precursor in the case of H₂ carrier gas. This influence of H₂ on microstructural morphology of Cu films yielded lower resistivity than Ar. A minimum value obtained under H₂ atmosphere was 2.37 μΩ cm.