Incorporating silicon atoms into a metal oxide gate dielectric using gas cluster ion beam implantation

摘要

An integrated circuit fabrication process is provided for forming silicon dioxide in the vacancies of a gate dielectric comprising metal oxide. The gate dielectric has a relatively high dielectric constant to promote high capacitive coupling between two conductive layers separated by the gate dielectric. The gate dielectric may be used in, e.g., a MOS transistor device or an EEPROM memory cell. The silicon dioxide is formed within the gate dielectric by first incorporating silicon atoms within the gate dielectric using gas cluster ion beam implantation. Gas cluster ion beam implantation affords shallow implantation of the silicon atoms. The gate dielectric is then annealed in a diffusion furnace while being exposed to a steam- or oxygen-bearing ambient. As a result of being heated, Si atoms react with O atoms to form SiO.sub.2 which fills oxygen vacancies in the gate dielectric. Absent the oxygen vacancies, the gate dielectric is less likely to allow current to leak between the two conductive layers. The SiO.sub.2 serves to terminate dangling bonds within the gate dielectric so that hot carriers and foreign species are substantially inhibited from being trapped within the gate dielectric.