Spectro-ellipsometric Analysis of Periodically Structured Samples

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1) Recent ultra fine structures in integrated circuits require new optical monitoring technology called optical scatterometry. In this research project, the scatterometry based on spectroscopic ellipsometry and also based on magneto-optic spectroscopy was applied to the analysis of periodically structured samples. In the theoretical calculations, coupled wave theory for gratings was introduced. Although integration circuits have a complicated structure, periodic structure is fabricated on a portion called teg for the monitoring of each lithography step.2) Results on the spectroscopic ellipsometry : Rectangular gratings with 250 nm period and 500 nm depth with various width ratio fabricated on a fused quartz substrate using an electron beam lithography and similar gratings with 130 nm period fabricated on a Si surface were analyzed and showed a good correspondence with cross sectional SEM images. Rectangular Ta wires fabricated on a fused quartz substrate required barreled cross section in the analysis and correspond well with SEM images. Two dimensionally distributed circular holes with 94 nm diameter, 180 nm pitch and 100 nm depth fabricated on a Si surface were analyzed by keeping lattice parameters. Values of the diameter and the depth correspond well with the SEM image of the cross section.3) Results on the magneto-optical spectroscopy: Nano-structures fabricated with ferromagnetic materials were analyzed. The magnetic nano-structure is aimed to monitor fabrication process of magneto-optic memory and magnetic random access memory (MRAM) and also aimed to study basic properties of magnetic nano-structure. They have anisotropic properties, so that optical response of magnetic nano-structure was summerized.