Measuring thickness of a film deposited onto a multilayer metal surface

摘要

Abstract: Measurement of the thickness of the top layer of a wafer having many film layers using microreflectometry normally requires detailed and rather accurate values of the thicknesses and optical properties of the underlying layers and substrate. In many cases such knowledge is unavailable; for example, the layers may be deposited sequentially in a process that does not allow the thickness measurements at each stage. A process is described to characterize the underlying layers and to determine an effective substrate that allows the accurate calculation of the top layer thickness in subsequent measurements. The procedure has been applied to antireflection coated aluminum, which is used in one stage of semiconductor manufacturing. Silicon dioxide thicknesses of 0.1 to 2.2 $mu@m determined using the procedure predict reflectances to within 0.6% of the measured values for wavelengths throughout the entire spectrum of 400 to 750 nm. !6