Carrier-density-wave depth profilometric measurements in semiconductor silicon wafers using laser infrared photothermal radiometry

The sensitivity of the photothermal radiometric signal to spatially localized damage for several different optical absorption depths is presented. Numerical simulations of the PTR response to the electronic parameters and optical penetration depth of the excitation source are presented and used to determine the uniqueness of the theoretical fit to the experimental frequency scans. Frequency scans are performed on both an intact Si wafer and on regions with damage on either the front or back surface and fit to the theory to determine the electronic properties of the wafer. A correlation between the sensitivity of the PTR signal to a defect and the proximity of the defect to the centroid of the injected excess carrier density is established, verifying the potential of spectroscopic PTR as a depth profilometric technique.