Measurement of SiC Epilayer Thickness Using Infrared Interferometry

Abstract

Accurate measurement of the thickness of silicon carbide (SiC) epitaxial layers is crucial for device performance. Although infrared interferometry offers the advantages of being non-destructive and highly precise, it has limitations in terms of model accuracy and data processing. To address these challenges, this paper establishes an improved measurement methodology. First, a dual-beam interference model is constructed to inversely determine the thickness by correlating interference fringes with wavelength and incident angle. Subsequently, an enhanced computational algorithm is implemented, which includes detrending of experimental spectra and the introduction of the Cauchy dispersion formula to correct for the wavelength-dependent refractive index. The thicknesses calculated based on data at incident angles of 10° and 15° are 7.39 μm and 7.33 μm, respectively, with a cross-validation relative error of only 0.82%. Further optimization using dual-angle joint fitting yields a thickness of 7.43 μm. The results demonstrate that the model exhibits good accuracy and robustness, providing a reliable non-destructive measurement method for SiC epitaxial layer characterization and contributing to quality control in semiconductor processes.