Leakage Current and Dielectric Properties of Ba_(0.5)Sr_(0.5)TiO_3 Films Deposited by RF Sputtering at Low Substrate Temperature

摘要

Most studies of Ba_(0.5)Sr_(0.5)TiO_3 (BST) thin film deposition have focused on chemical vapor deposition or spin-on techniques. Both these techniques require high substrate temperature (greater than 600 ℃), either during the deposition or during an anneal after deposition. A few groups have reported on sputtered films, but most of these studies also used high-temperature processes. While such temperatures are compatible with poly-Si plug DRAM and related technologies, they are far above the limits for technologies that require the deposition of non-refractory metals before the deposition of the ceramic film. For example, the use of Al metalization before the deposition of BST would limit the BST processing temperature to about 450 ℃. A process compatible with such a temperature limit is reported. Such a process makes fabrication of high quality BST thin films difficult, primarily due to the need for oxidation and grain growth in the ceramic. The leakage current and dielectric properties of BST films deposited in such a process are reported and are shown to be sufficient for practical device applications.