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[lxb97409]

Hi everyong:
What is the difference bwtween Minimum channel length of the transistor
and the minimum feature size of the process?

Thank you!
lxb97409

 

[uladz55]

Hi,

The minimum feature size is the minimum size which can be created repeatably by process (lithography, etching ...).

The minimum MOST length is the minimum gate length of transistor which can operate repeatably under conditions, declared by foundry.

For example, TSMC 0.18u process provide 0.18u gate length for 1.8V MOST and 0.3u gate length for 3.0V MOST.
And TSMC 0.5u process provide 0.5u gate length for 5V MOST and 3.0u gate length for 40V MOST.

 

[flyinspace]

Generally speaking, minimum channel length of the transistor and the minimum feature size of the process is the same value. We are not necessary to distinguish them for normal application.

 

[electronrancher]

that's true in some cases (for designer) but for layout, an analog guy sees much more of this feature sizing than SCMOS digital guy..

for example - a 0.5um process can have 0.5um gate length, but gate spacing can only be 0.6um. very important for cascode current source.

another example - 0.25um process may have 0.4um minimum metal 1, in order to properly surround 0.25um^2 contact size. in this case, the smallest feature is the 0.25um contact, but metal is no longer minimum.

true analog processes let you use every last micron for layout, but the rules are much more complicated than SCMOS digital processes.

in a normal SCMOS process, your minimum contact would be 2*lambda, or 0.25um, but minimum metal width and metal spacing would be 4*lambda, or 0.5um. not quite as dense as the 0.4um allowed in analog rules.

so basically - yes, minimum feature size will definately tell you minimum gate length (haha - that's the whole point) but the entire process will not necessarily use minimums.

 

[omsi]

hi,
minimum feature size is the one the process can create minimum size .based on this we define the process technology.
so , it is same as the minimum gate length.
but ,it can create the more size devices but the worst case is the minimum size

 

[yaxazaa]

min length is electric, min feature is physical