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I need help designing a floating gate

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mathi

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floating gate

Hi I need to make a floating gate and I am new to layouts, I have already tried to putting poly-2 over poly-1 of a regular nmos transistor. This caused a problem with drc saying poly-2 is not allowed over active region so i split up the active regions for source and drain into two pieces, would this be a problem? Also can contacts be used to connect poly-1 and poly-2? If anyone has any information that can help me with this i would really appreciate it.

I am using cmc cmosp35.

thanks.
 

Re: floating gate

The only way I know of to have a floating gate is to just not tie the gate to anything. In other words, if you have an inverter, nand, nor, etc. than you just tie the source, drain, bulk to whatever the schematic says and don't hook up the gate. That will cause it to be floating when you run LVS.

As for connecting Poly1 to Poly2, there should be a p1p2 contact in your standard cells library that allows you to do this.

Hope that helps
 

floating gate

"split up the active regions for source and drain into two pieces" U mean no active region under ploy?
If u do that, How the thin oxide fabricated under the ploy, then how to generated the channel.
 

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    mathi

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Re: floating gate

"split up the active regions for source and drain into two pieces" U mean no active region under ploy?
If u do that, How the thin oxide fabricated under the ploy, then how to generated the channel.

thats what i meant. Maybe thats is why the transistor is not working. Also would a contact connect poly-2 to metal-1?
 

Re: floating gate

You are right the poly would not have a connection if you took the active from underneath it. It's when poly crosses over active that it makes a transistor. So, your LVS would be wrong if you ran it that way. The only way to connect poly2 to met1 is to use a p1p2 contact which specifically contacts poly 1 to poly 2, and then put a regular poly contact to metal. Does your process allow stacking of contacts? If it does than you just sit one on top of the other, if not then stick them side by side. =)
 

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    mathi

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