Selective Nitride Etching with Phosphoric and Sulfuric Acid Mixtures Using a Single-Wafer Wet Processor

Selective nitride etching in semiconductor manufacturing is currently performed in wet benches using hot orthophosphoric acid at 160-180C. This process requires silica seasoning to achieve the desired selectivity to silicon oxide. Silica seasoning in wet benches is achieved by etching blanket silicon nitride wafers prior to running productions runs. While, this method of selective silicon nitride etching has been successful in the past, particle requirements at advanced nodes [1] are driving the need for a new solution. Single wafer wet processing is proposed as a way to meet these challenging new particle specifications.