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Journal of Display Technology

Journal of Display Technology


  • Vol. 10, Iss. 1 — Jan. 1, 2014
  • pp: 57–70

Refractive Index and Effective Thickness Measurement System for the RGB Color Filter Coatings With Absorption and Scattering Properties

Yen-Min Lee, Hsin-Hung Cheng, Jia-Han Li, Kuen-Yu Tsai, and Yu-Tian Sheng

Journal of Display Technology, Vol. 10, Issue 1, pp. 57-70 (2014)

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During the manufacturing processes of the thin-film transistor liquid-crystal display (TFT-LCD) panel, red, green, and blue (RGB) color filter coatings undergo the layer-adding process which causes the rough surfaces between the layers. The rough surfaces make acquiring an accurate measurement of the optical properties and thickness $(n, k, d)$ much more difficult because the scattering effects occur. The effective layer-included model is considered in determining the $(n, k, d)$ by including effective layers to reside between and above the multilayer (ML). To show the feasibility of the effective layer-included model, we examined the model by fitting the $(n, k, d)$ for different virtual systems which contain different kinds of scatters reside between and above it. Our findings show that the fitted $(n, k, d)$ can be closer to the assumed $(n, k, d)$ by using the effective layer-included model rather than the standard model. Also, the tolerance of initial assigned $(n, k, d)$ regions to obtain the accurate results are investigated. Further, both models are used to determine the $(n, k, d)$ of the fabricated RGB color filter samples. In the experimental measurements, all reflection and transmission signals are measured by utilizing the in-house variable angle spectroscopic ellipsometry (VASE) system. Consequently, the thicknesses determined from effective layer-included model are closer to the thicknesses measured from profilometry (Alpha-step 100). Also, the transmissions under 0 $^{\circ}$ , 15 $^{\circ}$ , and 30 $^{\circ}$ illuminations calculated from the fitted $(n, k, d)$ through the effective layer-included model are closer to the VASE measurements rather than the standard model for each sample. We conclude that the effective layer-included model can be used to determine the accurate $(n, k, d)$ of RGB color filter coatings with rough surface.

© 2013 IEEE

Yen-Min Lee, Hsin-Hung Cheng, Jia-Han Li, Kuen-Yu Tsai, and Yu-Tian Sheng, "Refractive Index and Effective Thickness Measurement System for the RGB Color Filter Coatings With Absorption and Scattering Properties," J. Display Technol. 10, 57-70 (2014)

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