At a step 202, a cleaning process uses one or more surfactants or detergents to clean the glass substrate (e.g., glass substrate 110). For example, the surfactants may include one or both of Valtron SP2200 detergent (commercially available from Valtech Corporation of Pottstown, Pa.) and LiquiNox detergent (commercially available from Alcanox, Inc. of White Plains, N.Y.). The cleaning process may include the use of ultrasonic energy and temperature control to increase cleaning capabilities.
During the cleaning process (e.g., step 202 or 302), a first tank 402 and a second tank 404 contain a surfactant such as a detergent. Tank 402 provides a first surfactant or detergent to the glass substrate and tank 404 provides a second surfactant or detergent. Tank 402 and tank 404 may include different surfactants (e.g., Valtron SP2200 and Liquinox) or the same surfactant. According to other exemplary embodiments, tank 402 or tank 404 may be omitted or skipped and cleaning/texturing system 400 may include or may use only one detergent tank. A third tank 406 is configured to rinse (e.g., a primary rinse) the glass substrate (e.g., using deionized water) after leaving tanks 402 and 404. A fourth tank 408 is configured to further rinse (e.g., a secondary rinse) the glass substrate and a fifth tank 410 is configured to dry the glass substrate after rinsing (e.g., using heating coils, blowers, etc).
When an ultrasonic/megasonic operation is employed for the sphere removal, most of spheres 26 are removed during the ultrasonic part of the operation. The ultrasonic operation is typically performed by placing the wafer in a bath of de-ionized water with a small volume percentage (e.g., 1%) of Valtron SP2200 alkaline detergent (2-butylxyethanol and non-ionic surfactant) and subjecting the bath to an ultrasonic frequency for 10 min. After removing the wafer from the ultrasonic bath, the wafer is rinsed with de-ionized water. The megasonic operation, performed after the ultrasonic operation to remove the remainder of spheres 26, typically entails placing the wafer in another bath of de-ionized water with a small volume percentage (e.g., 0.5%) of Valtron SP2200 alkaline detergent and subjecting the bath to a megasonic frequency for 15 min. The wafer is subsequently removed from the megasonic bath, rinsed with de-ionized water, and spun dry.
A detergent which largely neutralizes the charges on particles 26 can be used in place of Valtron SP2200 detergent during both the ultrasonic and megasonic operations. The charge-neutralizing detergent typically includes ionic surfactant.