Composition profiling of graded dielectric function materials by spectroscopic ellipsometry

Graded composition layers in transparent materials was characterized using spectroscopic ellipsometry (SE) was described. In modeling studies on the sensitivity limits of the technique, it has been shown that for known index profile shapes, the depth sensitivity can be quite high. Leached alkali-aluminosilicate and modified lead silicate glasses were examined by SE to confirm the predictions on the composition depth profiling. Good correlation between the SE-determined depth profile and secondary ion mass spectrometry (SIMS) measurements was obtained for the case of the modified lead silicate glass. For the aluminosilicate glass, simultaneous roughening of the glass surface during etching makes composition profiling more difficult.