Light Emitted Diode on Detecting Thin-Film Transistor through Line-Scan Photosensor

This paper explores the effectiveness of the white, red, green, and blue light emitted diodes (LEDs) light sources to detect the third layer of the electrode pixel and the fourth layer of the via-hole passivation on thin-film transistors. The time-delay-integration charge-coupled device and a reflective spectrometer were implemented in this experiment. The optical conditions are the same, as each light source and the digital image's binary method also recognize the sharpness and contrast in the task. Consequently, the white and the blue LED light sources can be candidates for the light source for the optical inspection, especially for monochromic blue LED's outperformance among the light sources. The blue LED demonstrates the high spatial resolution and short wavelength's greater energy to trigger the photosensor. Additionally, the metal material has shown a tremendous responsibility in the photosensor with 150 Dn/nj/cm² over the sensibility. The mercury ¹⁹⁸Hg-pencil discharge lamp emits the stable spectral wavelength to significantly calibrate the spectrometer's measurement.