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An innovative self-interferometric pupil ellipsometry(SIPE) has been demonstrated to overcome the spectral sensitivity and throughput limitations for optical critical dimensions (OCD) metrology in the advanced semiconductor devices. The two orthogonally polarized lights from the target structure on wafer were combined through suitably devised polarization state analyzer to generate an interferometric fringe pattern on the pupil surface of the SIPE optical system. The measured fringe pattern was processed with our novel holographic reconstruction algorithm to extract the ellipsometric information (Ψ and Δ) with the entire incident angles 0 to 70º and azimuthal angle 0 to 360º separately. In contrast to conventional ellipsometry tools, no mechanical movements were required to obtain the multi-angular information. To verify the usefulness of SIPE system and the algorithms, both experimental and theoretical validation have been performed for patterned wafers as well as for SiO2 mono-layered wafers. We first measured the non-patterned wafers of various different thicknesses, and found that the obtained values from SIPE, commercial ellipsometry tool, and theoretical simulation present a good agreement for wide spectral and angular ranges. Furthermore, we show that the large amount of angle resolved information from SIPE technique can greatly enhance the ability to overcome the OCD ellipsometry’s recent challenges such as spectral sensitivity issues, parameter correlation and structural asymmetry problems, etc. In short, the proposed system and algorithms, which are completely new approaches, show a capability to overcome current metrology challenges and we strongly believe that the SIPE is a promising metrology solution that can be eventually replacing the traditional OCD metrology tools..
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