Combined atomic layer and chemical vapor deposition, and selective growth of Ge₂Sb₂Te₅ films on TiN/W contact plag

The selective growth of stochiometric Ge₂Sb₂Te ₅ (GST) on the TiN plugging material in the contact hole that was formed in the SiO₂ dielectric layer was studied by atomic layer desorption (ALD) and chemical vapor desorpion (CVD). A contact structure with a top open diameter of 300 nm having TiN/W plugging material in a 500 nm thick SiO₂ layer was fabricated to test the selective growth behavior. The variations in layer density of each component of the GST films on TiN substrate is explained as a function of precursor purge time and injection time. The layer density of Ge increases with increasing injection time up to 2.5 s and then saturates, while the variation of the layer densities of Sb and Te with increasing precursor purge time of Ge is found. The GST film composition is found to be saturated to the stichiometric value after a precursor purge time of 4s.