Hydrogen-plasma-assisted hybrid atomic layer deposition of Ir thin film as novel Cu diffusion barrier

We investigated the effect of hydrogen plasma on the growth behavior of Ir thin films using hybrid plasma-enhanced atomic layer deposition (ALD). To increase the rate of adsorption onto the surface of Si substrates, which is considered to be the bottleneck in Ir ALD, hydrogen was co-fed into the chamber with an Ir metalorganic precursor formed by mixing the Ir precursor and reactant species in the same cycle. The hydrogen plasma effectively decomposes the Ir metalorganic precursors, resulting in an increase in the adsorption rate. A uniform, 5-nm-thick Ir thin film was grown on a Si substrate with a sharp interface between the substrate and film in less than 50 deposition cycle. Moreover, the dependence of the thickness on the number of deposition cycles shows a linear relationship, which is characteristic of the self-limiting nature of ALD. Compared with conventional oxygen and ammonia reactants, the process time required to deposit a 5-nm-thick Ir layer was remarkably reduced from 200 to 50 cycles by mixing the reactant species with the metal precursor. X-ray diffraction analysis revealed that poly-crystalline Ir was grown with preferential growth in the (111) direction. Our study suggests that the hybrid ALD method can be applied to a mass production line to reduce process time while maintaining the same film quality.