Advanced transistors (FinFET and GAA)

In very small transistors, what is the phenomenon called in which the threshold voltage varies because of statistical variation in the number and positions of dopant atoms in the channel?

  1. ARandom dopant fluctuation (RDF)
  2. BElectromigration
  3. CTime-dependent dielectric breakdown (TDDB)
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Answer: A. Random dopant fluctuation (RDF)

As transistors shrink, the channel contains only tens to hundreds of dopant atoms, and random variation in their number and placement strongly affects the threshold voltage. FinFETs and FD-SOI, which allow lightly doped channels, have an advantage in this respect too.

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More Advanced transistors (FinFET and GAA) questions

  1. Compared with FinFETs, what is a design advantage of nanosheet GAA transistors?
  2. Which technique, used to make the thin fins of FinFETs, uses sidewall spacers to create patterns finer than the lithography limit?
  3. In manufacturing nanosheet GAA transistors, why is only the SiGe selectively removed from stacked alternating Si and SiGe layers?
  4. What is the cause of self-heating, which tends to be a problem in FinFETs and SOI transistors?
  5. In highly scaled transistors, which factors are becoming increasingly important limits on performance?