| 摘要 |
<p>PURPOSE: To accurately measure the thickness of a wafer to be measured by obtaining a plurality of temporary difference absorbance spectra in which the thickness of the wafer to be measured is varied as a variable, and obtaining the thickness of the wafer from the thickness variable of the wafer at the time of vanishing the peak based on the phonon absorption on the difference absorbance spectra. CONSTITUTION: Parallel polarized infrared lights are incident on a reference wafer having a known thickness and a wafer to be measured having an unknown thickness at the Brewster angle, and the spectrum of the transmitted light is measured. Temporary difference absorbance spectrum is obtained in the case that the variable is varied with the thickness of the wafer to be measured as the variable from the spectrum after the reference wafer is transmitted, the spectrum after the measured wafer is transmitted and the thickness of the reference wafer. When the plurality of the temporary difference absorbance spectra are compared and observed, the difference absorbance spectrum in which the peak is vanished based on the phonon absorption of silicon exists in the case of the certain variable. The actual thickness of the measured wafer can be accurately calculated from the thickness variable of the measured wafer.</p> |
