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Modeling >> Semiconductor Devices >> Jmelt Jmax for BSIM in spectre
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Message started by jbdavid on Jan 17^th, 2007, 4:13pm

Title: Jmelt Jmax for BSIM in spectre
Post by jbdavid on Jan 17^th, 2007, 4:13pm

I was hoping to use these, to get current density warnings, but spectre manuals tell me these are Amps/um^2..
I'm assuming 1 dimension is transistor W, but the other cannot be Length.. , has to be depth..
of WHAT?

What I want to specify is similar to TSMC manual, Jeff = Id/w

BSIM spec does NOT mention these parameters at all.. and Spectre manual doesn't explain how to get Jds from Ids!

Guess I have to write assertions for this instead..
If someone knows what thickness would be used, please post it here..

Title: Re: Jmelt Jmax for BSIM in spectre
Post by marekm on Jan 17^th, 2007, 4:35pm

I don't know about Spectre, but usually those explosion limits apply to p-n junctions so I would suspect that they refer to the s/d areas for the junction diodes.

Title: Re: Jmelt Jmax for BSIM in spectre
Post by jbdavid on Jan 17^th, 2007, 5:56pm

Id wouldn't flow thru the junction diodes though..
and these aren't described in the Junction Diode parameter section.
But I hadn't really considered that possibility..
jbd

Title: Re: Jmelt Jmax for BSIM in spectre
Post by Ken Kundert on Jan 17^th, 2007, 7:00pm

I think marekm is right. I think those are parameters for the substrate junctions.

-Ken

Title: Re: Jmelt Jmax for BSIM in spectre
Post by Geoffrey_Coram on Jan 18^th, 2007, 4:14am

imelt, jmelt are in the diode section

imax, jmax are in a section with alarm, vbox which aren't diode parameters.

Jonathan - did you try it? Can you get a jmax warning with drain current? It might be that the units listed are wrong (or A/m^2 is used for the diodes, and A/m is used for the drain current).

-Geoffrey

Title: Re: Jmelt Jmax for BSIM in spectre
Post by Ken Kundert on Jan 18^th, 2007, 8:25am

Both the max and melt parameters apply to the junction diodes. The max parameters specify where the IV curves deviate from the expected exponential so as to improve convergence, and the melt parameters specify when a warning should be given. This is all explained in "spectre -h bsim3v3" under a special section titled "Imax and Imelt".

-Ken

Title: Re: Jmelt Jmax for BSIM in spectre
Post by jbdavid on Jan 18^th, 2007, 3:46pm

And Geoff verified that thru simulation..
- so for me thats a dead end, since what I need is Ids/Wmetal < Jmax Metal..
Appreciate the quick help!!
jbd

Title: Re: Jmelt Jmax for BSIM in spectre
Post by Ken Kundert on Jan 19^th, 2007, 12:29am

You might look into the new assertion features in Spectre.

-Ken

Title: Re: Jmelt Jmax for BSIM in spectre
Post by jbdavid on Jan 22^nd, 2007, 8:50pm

Reading about Jmax made me hopeful that I could avoid that.. but Geoff dashed those hopes..
guess its about time to play with those ..
Jonathan

Title: Re: Jmelt Jmax for BSIM in spectre
Post by Andrew Beckett on Jan 23^rd, 2007, 2:04am

Hi Jonathan,

assert is very easy to use. spectre -h assert gives you a very good starting point (as you'd expect). So there's no need to be fearful of using asserts!

Regards,

Andrew.