Quantitative analysis of interfacial impurities using secondary-ion mass spectrometry

A new secondary-ion mass spectrometry technique is described which permits quantitative analysis of impurities at buried interfaces. The technique utilizes the cascade mixing which accompanies sputtering to mix, and dilute, interfacial impurities into the surrounding matrix to such an extent that ion yields through the interface region are constant and characteristic of the matrix. Comparison with ion-implanted standards then yields analyses accurate to better than 30% (limited by knowledge of the standards) with a statistical uncertainty of 2%.