Apparatus and method for indirect surface cleaning

Abstract

Methods for cleaning a surface of a photomask and for increasing the useable lifetime of the photomask are disclosed. One method includes, a first wafer print processing using a photomask and a pellicle disposed across the photomask, and cleaning the photomask. The cleaning the photomask includes directing a laser beam through the pellicle toward the photomask, the laser beam having a wavelength that is substantially equal to a local maximum of an absorption spectrum of the photomask, heating the photomask with the laser beam, and transferring heat from the photomask to a contaminant disposed on the photomask, thereby thermally decomposing the contaminant.

Dependencies are inferred from the claim text.