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Modeling >> Semiconductor Devices >> poly resistor vs nwell for 1/f noise
https://designers-guide.org/forum/YaBB.pl?num=1277760195

Message started by rfcooltools.com on Jun 28^th, 2010, 2:23pm

Title: poly resistor vs nwell for 1/f noise
Post by rfcooltools.com on Jun 28^th, 2010, 2:23pm

poly sheet rho 310 Ohms/sqr
nwell 890 Ohms/sqr
same total area
1/f noise for poly is 20x greater than nwell!
Can anyone shed some light on this? is it right?

http://rfcooltools.com

Title: Re: poly resistor vs nwell for 1/f noise
Post by vivkr on Jun 29^th, 2010, 5:23am

If I had to take a guess, I would say that the higher 1/f noise in poly resistors is expected due to 2 reasons:

1. Poly is semi-crystalline (polycrystalline if you will) and hence the likelihood of greater number of places for electrons to get trapped, although.

2. An Nwell resistor likely has much more current flowing away from the silicon surface and hence fewer traps.

That being said, I would imagine that the trends ought to be very strongly process dependent. Any process guys out there?

Vivek

Title: Re: poly resistor vs nwell for 1/f noise
Post by rfcooltools.com on Jun 29^th, 2010, 1:13pm

vivkr,

Thanks for your reply, I did some checking around and your assessment is consistent with the info I have picked up.
here is what I found
charge trapping and de-trapping events at the poly-silicon boundaries is the cause of 1/f noise in poly resistors. While I have not been able to find any literature on nwell 1/f your explanation of current not traveling at the surface seems reasonable since crystalline Si has minimal traps.
Thanks,
http://rfcooltools.com

Title: Re: poly resistor vs nwell for 1/f noise
Post by hande.vinayak on Aug 18^th, 2010, 5:04am

Please, can you tell me the flicker noise in MOSFET or Poly resistor or NWELL resistor is more dominant?
Thanks.