A Dual Side Electroluminescence Measurement System for LED Wafer Manufacturing

A measurement system is presented for evaluating the characteristics of both sides of an LED wafer using electroluminescence (EL). Integrating spheres (IS), photodiodes, pico-ammeters, spectrometers were installed in the front and rear sides to measure optical characteristics with minimum EL loss. A probe was connected to a source meter with a thin wire and attached using a transparent fixture in the front IS. The EL characteristics in a measuring point were peak wavelength, FWHM (full width at half maximum), forward current, forward voltage and reverse current. EL images were created by combining the motion of a stage and the EL characteristics. The correlation between the EL and the chip-level tests and the repeatability test showed that the dual measurement is useful for LED manufacturing. Our patents were applied to install the probe and create the EL image.