What does Spice LEVEL x model mean ?

[manili]

Hello all,
I'm sorry if here is not a good place to ask this.
I'm a beginner in learning spice so maybe my questions seems stupid and I'm sorry before asking them.
What does Spice LEVEL x model mean ?
In this model I did not saw any specific width or length, why ?

Thank you very much

 

[dick_freebird]

Early SPICE MOS models, those predating BSIM, were given
LEVEL=1 (simplest), =2, =3, ... with more and more features /
accuracy added along the way. These are your LEVEL='X'.

Models are geometry independent (incorporating geometry
fitting params, to make that the case) so that the instance
can be so-paramterized rather then needing another model
for each geometry, of which there are semi-infinite possibilities.

 

[manili]

Early SPICE MOS models, those predating BSIM, were given
LEVEL=1 (simplest), =2, =3, ... with more and more features /
accuracy added along the way. These are your LEVEL='X'.

Models are geometry independent (incorporating geometry
fitting params, to make that the case) so that the instance
can be so-paramterized rather then needing another model
for each geometry, of which there are semi-infinite possibilities.

Thank you very much for your helpful replay.
So what should I do if I want to use that model in 180 nm feature size ? Is it necessary to make any changes to model or That's enough to only add L = 180nm and W = x nm ?
Thanks a lot