(A) Study on the RTD type temperature sensors for wafer level package LED

Abstract

In this thesis, a nickel based Resistance Temperature Detector (RTD) which integrated into the LED package for measuring the package temperature in real-time has been proposed and implemented. A stable metallic film is required for the long term reliability and stability of RTD type temperature sensor. Therefore, deposition and annealing condition for stable thin film were determined. The characteristic features of the thin film are determined by the film thickness, the deposition temperature, the annealing temperature, and the etc. As the result, the most stable thin film requires the particular condition to be formed; after deposited from the temperature, at 177˚C, to the thickness, 100nm, annealed in nitrogen ambient for an hour at 400˚C. Among this condition, the resistivity of the thin film is 7.629μΩcm, which is closed to the resistivity, 6.9μΩcm. Based on the current deposition, the 105μm by 10μm size of RTD was fabricated by the deposition and patterning processes. The line width and the line spaced were determined as 5μm by the previous pattern-ing test. Moreover, in order to improve the sensitivity through the increasing the resistance, the RTD had a serpentine structure. The changing in resistance was linearly increased by the changing the condition in the temperature from 0˚C to 140˚C. In addition, the RTD exhibited the resistance, 302.65Ω and the TCR, 0.00516˚C-1 at the particular temperature, 25˚C. Consequently, the RTD was confirmed about being able to monitoring the proper temperature of the LED packages. The LED package system, which has constant brightness regardless changing temperature, was pro-posed and implemented by compensating the optical properties in changing temperature condition. When the resistance of the RTD was changed by the package temperature, the changing resistance was converted to voltage through the conversion circuit. Additionally, the system noise was decreased through the low pass filter, and the output voltage was am...