Correlation between 1/f noise and h/sub FE/ long-term instability in silicon bipolar devices

Accelerated life tests with high-temperature storage and electric aging for n/sup +/-p-n silicon planar transistors were carried out. Current gain h/sub FE/ increases monotonously with time during the tests, and the h/sub FE/ drift is correlated with initial measured 1/f noise in the transistors, i.e. the drift amount significantly increases with the increase of noise level. The correlation coefficient of relative drift Delta h/sub FE//h/sub FE/ and 1/f noise spectral density S/sub iB/(f) is far larger than that of Delta h/sub FE//h/sub FE/ and initial DC parameters of the transistors. A quantitative theory model for the h/sub FE/ drift has been developed and explains the h/sub FE/ drift behavior in the tests, which suggests that the h/sub FE/ drift and 1/f noise can be attributed to the same physical origin, and both are caused by the modulation of the oxide traps near the Si-SiO/sub 2/ interface to Si surface recombination. 1/f noise measurement, therefore, may be used as a fast and nondestructive means to predict the long-term instability in bipolar transistors.<
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