Variation-free baseline with p-polarized Brewster incidence for infrared measurement of carbon impurities in silicon wafer

Abstract

In our previous infrared transmission study, the baseline variation [H. Saito and H. Shirai, J. Electrochem. Soc. 147, 1210 (2000)] appeared near the carbon impurity band at 605 cm−1 in the normal incidence infrared spectra of silicon. This occurs because of the diminishing of multiple reflections due to the strong two-phonon absorption in the range of 610–630 cm−1 and the difference in resistivity between the test and reference samples. To solve the problem of baseline variations, p-polarized Brewster incidence has been successfully applied to infrared measurements of carbon impurities in wafer-thick silicon samples. No baseline variations have appeared in this range, owing to the absence of multiple reflections.