System and method for recycling developer solution containing tetra-methyl-ammonia hydroxide (TMAH)

摘要

A method and system of TMAH concentration adjustment. Absorption values A1, Y1 to Ym of a recycled developer solution at wavelength 210 nm and m wavelengths between 220 nm and 250 nm are measured respectively, wherein m is equal to or greater than 2. Y1 to Ym are input to an nth-degree polynomial to generate a wavelength-absorption relationship Y=C₁Xⁿ+ . . . +C_n−1X+C_n, wherein X is wavelength, n is a positive integer and C₁ to C_n are coefficients of the relationship. Wavelength 210 nm is input into the wavelength-absorption relationship to generate an absorption value Y₂₁₀. A difference A3 between the A1 and Y₂₁₀ is calculated as the absorption value of TMAH in the developer solution and A3 is then input to an absorption calibration curve of TMAH at 210 nm to generate a corresponding TMAH concentration. TMAH is then added to provide the corresponding TMAH concentration.