On the geometry dependence of the 1/f noise in CMOS compatible junction diodes

This paper examines in detail the low-frequency (LF) noise behavior of Si n (+)p junction diodes in forward operation. Diodes fabricated on various typ es of Si substrates (FZ, epitaxial, and Ct) and with different geometries a re studied in the current range 0.1-250 mu A in order to investigate the im pact of these parameters. It is demonstrated that different kinds of 1/f no ise behavior can be distinguished which point toward a different origin. Th e nature of the 1/f noise is most clearly identified by inspecting the vari ation of the frequency exponent with forward bias. On the one hand, what co uld be called "peripheral" or "surface" 1/f noise shows a frequency exponen t which reduces with increasing forward current, a trend which is also obse rved for the corresponding ideality factor. When the 1/f noise is predomina ntly generated in the volume of the material (bulk origin), a more or less constant frequency exponent is found. It is also concluded that in many cas es, no unique area or perimeter dependence is found when comparing the nois e power spectral density of diodes with a different geometry. It will final ly be shown that there exists a close correlation between the different 1/f noise sources and the different reverse current components, which are a se nsitive function of the starting material characteristics and processing de tails.