Chemical vapor deposition method for forming SiO.sub.2

A method of forming a silicon oxide film on a substrate surface by chemical vapor deposition, comprising the steps of:

• heating a substrate in a reaction chamber;
• feeding a gas mixture of a first reactant gas comprising an organosilicon compound gas and a second reactant gas which is an oxygen gas containing ozone and which reacts relatively mildly with the organosilicon compound gas into the reaction chamber;
• and
• feeding a third reactant gas which is a gas comprising a halogen-containing silicon compound and which reacts with said organosilicon compound gas more vigorously than said second reactant gas, directly into the reaction chamber such that the third reactant gas comes into contact with and mixes with said gas mixture in the vicinity of the substrate surface, wherein said halogen-containing silicon compound is selected from the group consisting of triethoxyfluorosilane, silicon tetrafluoride and silicon tetrachloride.

A method of forming a silicon oxide film on a substrate surface by chemical vapor deposition, comprising the steps of:

• heating a substrate in a reaction chamber;
• feeding into the reaction chamber a gas mixture of a first reactant gas comprising an organosilicon compound gas and a second reactant gas selected from the group consisting of water vapor and hydrogen peroxide vapor and which reacts relatively mildly with the organosilicon compound gas;
• and
• feeding a third reactant gas which is an oxygen gas containing ozone and which reacts with said organosilicon compound gas more vigorously than said second reactant gas, directly into the reaction chamber such that the third reactant gas comes into contact with and mixes with said gas mixture in the vicinity of the substrate surface.

A method of forming a silicon oxide film on a substrate surface by chemical vapor deposition, comprising the steps of:

• heating a substrate in a reaction chamber;
• feeding into the reaction chamber a gas mixture of a first reactant gas comprising an organosilicon compound gas and a second reactant gas selected from the group consisting of water vapor and hydrogen peroxide vapor and which reacts relatively mildly with the organosilicon compound gas;
• and
• feeding a third reactant gas which is a gas comprising a halogen-containing silicon compound selected from the group consisting of triethoxyfluorosilane, silicon tetrafluoride and silicon tetrachloride and which reacts with said organosilicon compound gas more vigorously than said second reactant gas, directly into the reaction chamber such that the third reactant gas comes into contact with and mixes with said gas mixture in the vicinity of the substrate surface.