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Random telegraph noise in a MOSFET appears as random variations in the drain
current under constant applied gate-to-source (V
GS
) and drain-to-source (V
DS
) voltage
bias. Electron trapping/detrapping is the presumed cause of RTN. It is innate to
semiconductor MOSFET devices, and it has always been present in MOS processes.
Until recently, RTN was mainly a concern of CMOS image sensor manufacturers, as
it would generate erroneous white spots in what should be dark areas. However, as
operating voltages have decreased and lithographies have continued to shrink, RTN
has begun to impact the stability of SRAM cells. Since virtually all integrated circuits
use SRAM for their cache memory, this is critically important to the semiconductor
industry. Virtually all the major industry players now must evaluate their processes for
susceptibility to RTN.
A major semiconductor manufacturer needed a reliable means to evaluate the impact of
RTN on its processes, and Keysight was able to provide a solution.
Figure 2. Random telegraph noise in a MOSFET