CONCENTRATION COMPUTING METHOD AND CONCENTRATION CONTROL SYSTEM FOR DEVELOPER INCLUDING PHOTORESIST

摘要

PURPOSE: A method for measuring the concentration of a developer including photoresist and a concentration regulating device are provided to reduce a waste of the developer by recovering the developer spread on a substrate when a developing process is progressing and to reduce the amount of the developer utilized for the developing process by directly regulating the concentration of the recovered developer. CONSTITUTION: A method for measuring the concentration of a developer including photoresist includes the following steps of: dissolving the photoresist in a developer of reference concentration and measuring absorbance with a nephelometer while increasing the amount of the photoresist dissolved in the developer at a predetermined speed; measuring a difference of the concentration of the developer per each of measured absorbance values with neutralimetry and obtaining a correlation function between the absorbance and a concentration error of the developer; measuring the concentration of carbonate by measuring the absorbance of a developer sample with a nephelometer and measuring the conductivity of the developer sample with a nephelometer and the speed of ultrasonic waves; and calculating the concentration of the developer sample by using the measured absorbance, the concentration of the carbonate, the correlation function between the absorbance and the concentration error of the developer, the correlation function between the concentration of the carbonate and the concentration error of the developer, and the reference concentration of the developer. [Reference numerals] (5) Densitometer; (AA) Ultrapure water; (BB) Undiluted solution of a developer (25%); (CC) Regeneration solution for a developer; (DD) Developer with reference concentration; (EE,FF) Developing machine; (GG) System for regenerating a developer