To enable a processing liquid that is optimally controlled in composition corresponding to its uses by a method wherein a semiconductor manufacturing device is equipped with a mixing tank where a processing liquid and additives supplied from tanks are mixed together, and a controller which controls the processing liquid and additives in volume so as to mix them at, an optimal ratio corresponding to uses.

A semiconductor manufacturing device 10 is equipped with a processing liquid tank 1, a solvent tank 2, an additive tank 3, a mixing tank 4, a nozzle 5, a CPU 6, and a memory 7. One or more processing tanks 3 contain a developing solution. One or more additive tanks keep a surfactant. These tanks are connected to the mixing tank 4 with pipings, the processing liquid and additive are fed at a prescribed ratio to the mixing tank 4 and mixed together. The mixed liquid is supplied from a nozzle 5 onto a semiconductor substrate. The CPU 6 is electrically connected to the tanks 1 to 3 and the mixing tank 4 to control the volumes of liquids fed to the mixing tank and the volume of a mixed liquid fed to nozzle 5.