PURPOSE: To eliminate micro defect from a fine pattern formed on a thin film or a cleaned surface which resist is exfoliated by cleaning the surface on a substrate from which photoresist is exfoliated or the surface for forming a thin film by the use of a specified ultrapure water.
CONSTITUTION: pH of waste water is controlled in the range of 5.4-6.8 and polyaluminate chloride of 75-100ppm is added to the waste water in order to aggregate and precipitate main impurities. Content of ionic Al in the water to be processed is then set at 10ppm or below and ion exchange is performed to produce high purity water. The high purity water is further subjected to ion exchange thus producing ultrapure water wherein 10,000-100,000 ultrafine particles having particle size in the range of 0.01-0.03μm are contained in 1ml of ion exchanged secondary pure water. The superpure water is then passed sequentially through a security filter of 0.1μm mesh and superfine filters of 0.2μm and 0.1μm meshes to produce ultrapure water which is employed in the exfoliation of photoresist applied on a silicon wafer or glass substrate or in the cleaning of surface for forming thin film.
KAWAGOE HIROMI
MORISHITA TOSHIKAZU
WATANABE SUMIKO
