Rotating compensator spectroscopic ellipsometry for line-width control

Abstract

Rotating compensator spectroscopic ellipsometry(RCSE) was applied to the characterization of linewidth in deep uv photoresist (PR) films. Variation of line-width in few nm was distinguishable by comparing the features in conventional ellipsometry parameter{∆, Ψ} or the degree of polarization spectra obtainable from RCSE. The variations in the former spectra were caused by the density change in patterned PR films. Meanwhile, the variations in latter spectra were caused by the surface profile of the film. Once the spectral positions of the features were related to the results of CD-SEM, both spectra could be used to estimate the line-width of patterned PR without in depth analysis. Further, when uniaxial anisotropy was assumed for the film, the line-width could be roughly deduced in the process of extracting the optical properties of film via an effective medium approximation.