A manufacturing a thin film transistor array panel includes depositing a first thin film including aluminum on a substrate, patterning the first thin film by photolithography and etching, cleansing the substrate including the first thin film, and depositing a second thin film on the cleansed substrate. The cleansing is performed using a cleansing material including ultrapure water, cyclic amine, pyrogallol, benzotrizole, and methyl glycol. The cleansing material includes ultrapure water at about 85 wt % to about 99 wt %, cyclic amine at about 0.01 wt % to about 1.0 wt %, pyrogallol at about 0.01 wt % to 1.0 wt %, benzotrizole at about 0.01 wt % to 1.0 wt %, and methyl glycol at about 0.01 wt % to 1.0 wt %.