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Abstract

The present invention provides methods for efficiently cleaning semiconductor wafers, and particularly for removing photoresist material from the surfaces of semiconductor wafers, using a mixture of sulfuric acid and hydrogen peroxide. In accordance with the present invention, an initial sulfuric acid-based photoresist stripping bath, either being pure sulfuric acid or a sulfuric acid:hydrogen peroxide mixture with a ratio of at least 15:0.3, based on the anhydrous chemical substances, is prepared for processing an initial batch of wafers. During the processing of the semiconductor wafers, hydrogen peroxide is added to the bath solution at a controlled rate of between about 0.015-1.5 g H.sub.2 O.sub.2 (anhydrous basis)/min./liter of photoresist bath solution. In such a way, the conversion of hydrogen peroxide to Caro's acid is optimized resulting in an extended bath life and conservation of hydrogen peroxide.

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First Claim