In recent years, miniaturization in semiconductor manufacturing technology increases a technical difficulty level in processing a contact hole, etc., so high etching selectivity in a layer of processing material such as silicon oxide with respect to a photoresist film has been required. Therefore, technical development has been proceeded by approaches from a lot of aspects such as used material, equipment, and processing method.
From such a situation, as a dry etching gas which is applicable to a state-of-the-art dry etching process, 1,3,3,3-tetrafluoropropene has been developed (Patent Document 1). As compared with carbon tetrafluoride, hexafluoro-1,3-butadiene, and fluorine, which are industrially widely used as an etching gas for a silicon-based material, this compound is capable of etching a silicon-based material with a high aspect ratio and a low side etching ratio with respect to the silicon-based material. Furthermore, this compound is capable of obtaining a good processing shape of a contact hole, so usability of this compound has been recognized. Furthermore, 1,3,3,3-tetrafluoropropene has zero ozone depleting potential and low GWP (global warming potential), so it is a material having low global environmental load as compared with perfluorocarbons and hydrofluorocarbons, which are generally used as an etching agent.
1,3,3,3-tetrafluoropropene has a double bond of carbon-carbon. A part of carbon-carbon bond is dissociated by plasma, and polymerization is proceeded. 1,3,3,3-tetrafluoropropene deposits polymers of fluorocarbon on an etching mask such as a photoresist film during etching. Thereby, etching of the mask is prevented, and etching selectivity between an etching object and the mask can be improved. Therefore, 1,3,3,3-tetrafluoropropene has attracted a lot of attentions as a dry etching gas which is applicable to a state-of-the-art dry etching process.
As a method for manufacturing 1,3,3,3-tetrafluoropropene, a method where 1-chloro-3,3,3-trifluoropropene and hydrogen fluoride are reacted (Patent Document 2); a method where CF3X and CXH═CHX (“X” is fluorine, chlorine, bromine, or iodine) are reacted (Patent Document 3); etc. are well-known.