DIFFUSING APPARATUS

PROBLEM TO BE SOLVED: To make the impurity concentration of a wafer in a reaction furnace uniform by providing an injector having a gas introducing port at the upper end of a reaction furnace, and an injector having a gas introducing port at the lower end. SOLUTION: A jig supporting wafers in multiple stages is introduced from a furnace port 3a into a reaction furnace 3, and reaction gas is introduced via the gas jet ports 4 of injectors 5A, 5B coupled bidirectionally. In this case, the gas is introduced via a plurality of jet ports from the one injector 4A, but gas pressures are different according to near to or remote from the port 6 at the jet port, and diffusing amounts become different. Accordingly, the other injector 5B is installed in a reverse direction at the upside down from the injector 5A to supplement the difference of the diffusing amounts from the jet ports at both sides, the gas concentration becomes uniform near the wafer supported at the center, thereby making it possible to make the impurity concentration to be diffused to the wafer uniform.