A semiconductor substrate is placed within a housing. By supplying organometallic complexes and carbon dioxide in a supercritical state into the housing, a BST thin film is formed on a platinum thin film, while at the same time, carbon compounds, which are produced when the BST thin film is formed are removed. The solubility of carbon compounds in the supercritical carbon dioxide is very high, and yet the viscosity of the supercritical carbon dioxide is low. Accordingly, the carbon compounds are removable efficiently from the BST thin film. An oxide or nitride film may also be formed by performing oxidation or nitriding at a low temperature using water in a supercritical or subcritical state, for example.