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Vt vs. Length of MOS (Read 7955 times)

RDCam

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Cambridge, UK

Vt vs. Length of MOS
Nov 27^th, 2006, 2:05am

I noticed the trend of Vt (threshold voltage) Vs. Length (um) for the low-vt nchannel MOS transistors in recent sub-micron technologies has changed. Previously the Vt for shorter channel lengths would be lower, but now it seems significantly higher cmopared to longer channel(>2u). The gradient of the Vt Vs L curve for L <~1.5u is very high. Are there any process experts who can explain this ? Will greatly appreciate any clarification on something that has been bugging me for a few months already!

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ACWWong Community Fellow Offline Posts: 539 Oxford, UK	Re: Vt vs. Length of MOS Reply #1 - Nov 27^th, 2006, 7:27am Perhaps you are seeing the "Reverse-short-channel effect" which is an increasing vth with decreasing L to a peak, before vth again decrease at very short channels.... perhaps your vth vs L hump is just under 1.5um. Try looking at something Tsividis "the MOS transistor" or googling it.
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RDCam New Member Offline Posts: 2 Cambridge, UK	Re: Vt vs. Length of MOS Reply #2 - Nov 28^th, 2006, 3:43am The keyword RSCE is exactly what I was looking for. Once I could label the phenomenon I am able to find literature on it ! Thanks a lot.
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Croaker Senior Member Offline Posts: 235	Re: Vt vs. Length of MOS Reply #3 - Nov 28^th, 2006, 8:36am Basically it has something to do with the way the p-dopant diffuses, creating a higher Vth, even though Vth should be getting lower with channel-length. Please post a link to any good explanatory page about this.
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