Plasma enhanced chemical vapor deposition of TiO₂ in microwave-radio frequency hybrid plasma reactor

A plasma tool and accompanying process have been developed for plasma enhanced chemical vapor deposition of TiO2 thin films for dynamic random access memory application. The microwave-rf (radio frequency) hybrid reactor consists of microwave power (2.45 GHz) for electron cyclotron resonance, a hollow cathode (0.1-30 MHz) for control of the plasma potential, and an additional rf (13.56 MHz) power to the substrate electrode for ion extraction and ion energy control. X-ray diffraction showed the anatase phase at a low deposition temperature below 400 °C, but the rutile phase dominanted above 400 °C. Low energy ion bombardment densifies the TiO2 films and suppresses rutile formation. A dielectric constant of 60(±5) at 1 MHz was obtained, independent of film thickness in a range from 20 to 200 nm. A SiO2 buffer layer was found to be important in order to prevent silicide formation and to keep the leakage current below 10–10 A/cm. © 1995, American Vacuum Society. All rights reserved.