| Summary: | 碩士 === 國立高雄應用科技大學 === 光電與通訊工程研究所 === 103 === The purposes of this study are to set up a noise measurement system, measure and quantitatively analyze the noises of CMOS-compatible microbolometer materials. In this work, the test samples of polysilicon and titanium silicide with different process conditions were fabricated. The noise spectrum and the temperature coefficient of resistance of each sample were measured and further analyzed. Especially, the effect of annealing temperature on the noise spectra of polysilicon films and the effect of the material volume on the noise spectra of silicide films were realized in this study. Eventually, the main noise of each sample was quantitatively characterized and the feasibility study of these CMOS materials on the application of microbolometers were figured out.
The spectral noise current of materials to be measured was first amplified by adopting a SR570 low noise current preamplifier and then read out by a SR780 dynamic signal analyzer. According to the noise analysis of the measurement results, the noises of polysilicon and titanium silicide at low frequency are dominated by frequency-dependent flicker noise, which results from the recombination effect on carrier traps and crystal defects in material. In general, the magnitude of flicker noise of a material can be characterized by a flicker noise constant k. The flicker noise constants of the polysilicon films with annealing temperature 950℃ and 1050℃ were measured and calculated as about 1.6E-25 m3 and 3.2E-27 m3. The measurement results show that the flicker noise of polysilicon can be obviously lowered by increasing annealing temperature. Analysis of the measurement results of different volume, the value k of the polysilicon with volume of 4000 μm3 and 40000 μm3 were estimated approximately 4.8E-27 m3 and 1.4E-25 m3 at annealing temperature of 950℃. The noise of polysilicon with larger volume was larger than the smaller volume. The flicker noise coefficient of titanium silicide device with thickness of 550 Å at about 1.78E-28 m3 can be achieved.
Keyword: flicker noise, CMOS-Compatible, NETD
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