Cleaning technique of hot-wall batch type Ru CVD equipment by oxygen gas

The gas cleaning of the hot-wall batch type Ru CVD reactor by oxygen was investigated. The cleaning mechanism is considered as follows. Below 800/spl deg/C, Ru film is oxidized and forms RuO/sub 2/ which is not volatile. But above 800/spl deg/C, RuO/sub 2/ film, which is formed at first, is oxidized again to form RuO/sub 4/. Since RuO/sub 4/ is volatile, it evaporates easily. High temperature, low pressure and high oxygen flow rate were required to obtain fast Ru etching rate. With these optimum cleaning conditions by design of experiments (DOE), 30-nm-thick Ru film was removed completely in 20 minutes. We could accomplish this in situ oxygen gas cleaning effectively in short time by using hot-wall batch type Ru CVD equipment, which has high heating and cooling rate characteristics.