Is threshold voltage of transistors decreases with decrease in technology? In 22 nm PTM CMOS model card, i found zero baised threshold voltage is higher compare to 32nm, 45nm......
Dear Sandeep Kumar ,
I am not sure but it might be due to reverse short channel effect.
"In MOSFETs, reverse short-channel effect (RSCE) is an increase of threshold voltage with decreasing channel length; this is the opposite of the usual short-channel effect. The difference comes from changes in doping profiles used in modern small device manufacturing"
Usually, the threshold voltage is lowered when the channel length decrease to a specific nano-meter size. Actually, both length and width shrinkage causes change in the threshold voltage. This is due to charge sharing and drain induced barrier lowering (DIBL). However, in aggressively sized nano-scale MOSFETS, there are new effects in play, mainly due to different gate geometry and doping profile.
Dear Sandeep Kumar ,
In order to explain the increase of the zero bias voltage of MOST with down scaling as you observed it form the specs one has to to refer to the return to the factors affecting it. Since by scaling one increases the doping of the channel, then consequently this will also increase the zero bias threshold voltage.
This may be the cause in the first glimpse. Otherwise more investigations are needed.
I would like that your refer to the book to get the expression of the Vt0 the zero boas threshold voltage:Book Electronic devices with physical insight
Best wishes
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