Ammonium Bicarbonate → Carbonic Acid

Participants

Reaction Steps

This example, using the present method, demonstrates the improvement resulting from the addition of bicarbonate ion to a solution of ozone in deionized water, as was used in Comparative Example 1. As in Comparative Example 1, 150 mm wafers with a blanket layer of photoresist were used for these experiments. The wafers were treated with 1.32 liters per minute of an aqueous solution containing about 7×10-4M ozone (36 ppm), and 0.01 M ammonium bicarbonate. The pH of this solution was slightly basic, with a value near 7.5. The net concentration of bicarbonate ion in solution was approximately 9×10-3M, as a result of the conversion of small amounts of bicarbonate ion to either carbonate ion or carbonic acid. FIG. 6a shows the amount of photoresist remaining on the wafer after processing as a function of treatment time while FIG. 6b shows the rate of removal of photoresist. The removal rate is constant, as in Comparative Example 1, but the inventive method results in a roughly 25% faster rate of removal. This benefit continues as the photoresist is removed down to the surface of the wafer, resulting in the complete removal of all photoresist from the wafer in 25% less time.

Provenance & Evidence