Treatment method and apparatus using a chemical reaction

In order to effectively remove gas molecules of a by-product in a chemical reaction in a solution so as to achieve high efficiency, high rate, and uniformity of the chemical reaction in the solution and in order to realize formation of a semiconductor substrate applicable to production of SOI structure and realize formation of a semiconductor substrate in which a light-emitting element or a gas sensor can be formed, on the basis of an inexpensive silicon substrate, the chemical reaction is performed while the concentration of a gas dissolved in a reaction solution in a reaction vessel is always controlled to be not more than the solubility thereof during the reaction. Further, a chemical reaction apparatus is disclosed which comprises a reaction vessel having a holding means for holding a substrate, for housing a reaction solution and carrying out the chemical reaction with the substrate therein, a circulation line for circulating the reaction solution outside the reaction vessel, a deaerating device provided on the circulation line, for removing the gas from the reaction solution, and a transfer device for transferring the reaction solution in the circulation line.