Thin film forming device and thin film forming method using the same

The disclosure relates to a thin film forming device and a thin film forming method using the same capable of improving the film quality of a silicon thin film by dividing a reaction space in a process chamber of the thin film forming device and thereby forming the silicon thin film on a substrate in a first space and treating a surface of the silicon thin film, formed in the first space, in a second space by using plasma. By the thin film forming device and the thin film forming method using the same according to the disclosure, with a trend that a pattern is complicated and the depth of the pattern increases, impurities in a thin film may be more efficiently removed, a uniform thin film may be formed on a pattern, and the grain size of the crystals of a silicon thin film may be made uniform.