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bicave
Joined: 19 Jun 2006
Posts: 60
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 21 Aug 2008 16:01 Why NMOS has snapback properties |
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I wonder how NMOS can have snapback,
ESD so complicated! I don;t know its behavior. Do you have any material illustrate it more clear.
Thanks
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pbs681
Joined: 19 Aug 2004
Posts: 154
Helped: 11
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| 22 Aug 2008 13:37 Re: Why NMOS has snapback properties |
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| NMOS transistor has parastic BJT npn. During snapback, this BJT transistor that conducting the current. So, the snapback current is actually a parasitic BJT current
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ssuchitav
Joined: 12 Jun 2006
Posts: 25
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| 24 Aug 2008 7:49 Re: Why NMOS has snapback properties |
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| Is this BJT current is triggered by high electric field near the drain junction? which is so called J-E heating?
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jordan76
Joined: 25 Mar 2004
Posts: 177
Helped: 4
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| 25 Aug 2008 3:06 Re: Why NMOS has snapback properties |
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Some explanations:
Due to high electric field at NMOS drain, electron-hole pairs are generated as a result of avalanche break-down, then parasitic BJT is triggered when source-substrate junction is forward-biased.
I assume you are referring to joule-heating by "J-E heating": the power consumed by Rsub of parasitic BJT.
Hope it helps.
Regards,
Jordan
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leebluer
Joined: 20 Apr 2004
Posts: 60
Helped: 2
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| 26 Aug 2008 10:35 Re: Why NMOS has snapback properties |
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| It perhaps before snapback only BVds affect; while P-sub current cause parastics NPN BE junction conduct, parastics NPN affect. Vce is smaller than BVds.
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