Composition of uncontrolled impurities and their chemical states and depth profiles at the Al–Si interface

Auger electron spectroscopy and secondary-ion mass spectrometry are used to study the compositions of uncontrolled impurity atoms, their chemical composition, and the atomic distribution profiles at the Al–Si interface. Low concentrations ($<$ 0.1%) of impurity C, O, N, Ti, Fe, and other atoms are detected in Al. An analysis of the chemical shifts of the Auger peaks of metal atoms shows that compounds of the AlO and Al$_2$O$_3$ types form at the Al–Si interface.