CHEMICAL DISSOLUTION OF UNREACTED FREE SILICON IN SILICON NITRIDE.

The search for a chemical method for selective and reproducible determination of the free (unreacted) silicon in silicon nitrides has led to the development of a generally applicable reagent that removes the free silicon from sections of polished samples. The etchant used is 60 ml HNO//3, 25 ml HF, and 3 to 5 drops of 30% hydrogen peroxide. The technique and the limitations of the analysis are discussed.