TY - JOUR
T1 - Phase-based method in heterodyne-modulated ellipsometer
AU - Tsai, Hsiu An
AU - Lo, Yu Lung
N1 - Funding Information:
The authors gratefully acknowledge the support provided to this study by the National Science Council of Taiwan under Grant No. NSC 98-2221-E-006-053-MY3.
PY - 2013/12
Y1 - 2013/12
N2 - A new common-path heterodyne-modulated ellipsometer with two-phase detection to measure the ellipsometric parameters of amplitude ratio (Ψ) and phase difference (Δ) between p- and s-polarizations of the thin film isotropic materials is proposed. Uniquely, the new scheme distinct from the other previous studies is only by taking two phases from heterodyne signals. Thus, the proposed system is a phase-sensitive modulated ellipsometer that can have the ability to measure the full range of the ellipsometric parameters with high sensitivity and eliminate the intensity fluctuation in system. The ability and performance of modulated ellipsometer on measurement of thin film thickness and ellipsometric parameters are verified by experiments. The errors regarding the ellipsometric parameter measurements are also discussed. The experimental results show that the average standard variation of measured ellipsometric parameters (Ψ and Δ) and the thickness measurement of silica thin film deposited on silicon substrate are 0.13, 0.94, and 0.55 nm, respectively. Accordingly, this new idea can be applied to measure isotropic thin film with extremely high absorbance that results in the poor signal/noise ratio in contrast extraction from heterodyne signals.
AB - A new common-path heterodyne-modulated ellipsometer with two-phase detection to measure the ellipsometric parameters of amplitude ratio (Ψ) and phase difference (Δ) between p- and s-polarizations of the thin film isotropic materials is proposed. Uniquely, the new scheme distinct from the other previous studies is only by taking two phases from heterodyne signals. Thus, the proposed system is a phase-sensitive modulated ellipsometer that can have the ability to measure the full range of the ellipsometric parameters with high sensitivity and eliminate the intensity fluctuation in system. The ability and performance of modulated ellipsometer on measurement of thin film thickness and ellipsometric parameters are verified by experiments. The errors regarding the ellipsometric parameter measurements are also discussed. The experimental results show that the average standard variation of measured ellipsometric parameters (Ψ and Δ) and the thickness measurement of silica thin film deposited on silicon substrate are 0.13, 0.94, and 0.55 nm, respectively. Accordingly, this new idea can be applied to measure isotropic thin film with extremely high absorbance that results in the poor signal/noise ratio in contrast extraction from heterodyne signals.
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U2 - 10.1007/s00340-013-5503-5
DO - 10.1007/s00340-013-5503-5
M3 - Article
AN - SCOPUS:84890968201
SN - 0946-2171
VL - 113
SP - 537
EP - 542
JO - Applied Physics B: Lasers and Optics
JF - Applied Physics B: Lasers and Optics
IS - 4
ER -