Abstract: A mask including a transparent substrate, a non-transmitting layer, a first transmitting layer and a second transmitting layer is provided. The transparent substrate has a first region, a second region, and a third region. The non-transmitting layer is disposed in the first region of the transparent substrate. The first transmitting layer is disposed in the second region and the third region of the transparent substrate. The second transmitting layer is disposed on the first transmitting layer in the third region.

Abstract: 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+ . . . +Cn−1X+Cn, wherein X is wavelength, n is a positive integer and C1 to Cn 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.