a treatment method for plate - shaped substrate capable of uniformly performing the treating operation , performing a large amount of treatment , and facilitating the automation of the work independently of the surface nature of the substrate such as base plates of si wafer for integrated circuit manufacturing use . the method is achieved by making it easier for the whole substrate surface to be wetted with the treatment liquid , through exposing the substrate to liquid or gas material which is soluble mutually with a treatment liquid prior to treatment with the treating liquid , to avoid treatment and thus uneven treatment to improve the yield .