Patent ID: 6800409
Filing Date: 2004-10-05
Classification: G03F

Abstract:
A method of recycling a photoresist developer solution containing tetra-methyl-ammonia hydroxide (TMAH), comprising:selecting m wavelengths between 220 nm and 250 nm, wherein m is equal to or larger than 2; measuring absorption values Y1 to Ym of the recycled developer solution at the m wavelengths respectively and an absorption value A1 at wavelength 210 nm; inputting the Y1 to Ym to an nth-degree polynomial, Y=C1Xn+ . . . +Cnâˆ’1X+Cn, to generate a wavelength-absorption relationship, wherein X is wavelength, n is a positive integer, and C1 to Cn are coefficients of the relation; inputting wavelength 210 nm into the wavelength-absorption relationship to generate an absorption value Y210; calculating a difference A3 between the A1 and Y210 as the absorption value of TMAH in the developer solution; inputting A3 to an absorption calibration curve of TMAH at 210 nm to generate a corresponding TMAH concentration; and adding TMAH into the recycled developer solution according to the corresponding TMAH concentration for reuse.