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A question about antenna effect

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Ryan1234

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Hi, dear all :
If i had antenna violation at metal 1, then i segment metal 1 into several parts.
And using the jmpers to connect them. This is a solution for antenna effect.
My question is :
When the metal 2 is fabricated, does the accumulated charges in different parts of metal 1 will convene through the jumpers ?
In that way, the total charges on the gate oxide won't change, so the gate oxide will be harmed. I am so confused.
Thank you!!
 

HI Ryan,
Please go through tis post.
Maybe it can clear your doubts.This a the discussion we had sometime ago.

Regards,
Kapil
 

    Ryan1234

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Thank Kapilsn's reply~
I finished studying all the messages and I gained a lot.
So the answer is :
The accumulated charges was flushed in the "wet cleaning" step before fabricating the next metal level.
If I am wrong, please correct me.
Thank you very much~
 

Ryan1234 said:
When the metal 2 is fabricated, does the accumulated charges in different parts of metal 1 will convene through the jumpers ?
In that way, the total charges on the gate oxide won't change, so the gate oxide will be harmed.
You're totally right: Shortly before the end of metal_2 etching, when all metal_2 areas are already separated and the connection between the metal_2 - via - metal_1 - contact - poly-gate is complete, the metal_2 parts of these connections catch charges from the ion beam, which will be distributed over the total connection. The metal_2 ARC (antenna rules' check) will check the ratio of the total connection area (from metal_2 to poly, which stores the caught charge) to the gate area, and if this ratio exceeds a certain limit (fixed by the foundry), it will flag an error.

So in this case "hopping" only between metal_1 & metal_2 won't help; it is necessary to hop up to a metal level where the fully completed individual wire connection guarantees access to a silicon region, mostly an inverter-like output and/or an ESD structure. So you simply must make sure, that at any metal-level etching the (until then) total connection area doesn't exceed the a.m. ratio limit. This should be possible, if you hop - not too far away from the gate(s) - to the highest metal level (used by the individual connection) and return to the original/required level.

Routing wires without any connection to silicon are seldom (because gate inputs usually are supplied by outputs), but not impossible, however: e.g. think of a series connection between a poly or MIM capacitor and a gate input.

If there is no contact to silicon (junction) at any metal level, you must provide a (normally) reverse-biased (minimum area) junction diode to the substrate (GND) or (better for draining off positive charges) to an n-well (VDD).
 

    Ryan1234

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erikl said:
Ryan1234 said:
When the metal 2 is fabricated, does the accumulated charges in different parts of metal 1 will convene through the jumpers ?
In that way, the total charges on the gate oxide won't change, so the gate oxide will be harmed.
You're totally right: Shortly before the end of metal_2 etching, when all metal_2 areas are already separated and the connection between the metal_2 - via - metal_1 - contact - poly-gate is complete, the metal_2 parts of these connections catch charges from the ion beam, which will be distributed over the total connection. The metal_2 ARC (antenna rules' check) will check the ratio of the total connection area (from metal_2 to poly, which stores the caught charge) to the gate area, and if this ratio exceeds a certain limit (fixed by the foundry), it will flag an error.
Thank your reply.
Are the charges in the above that you mentioned caused by metal_2 etching?
My question is focus on the charges by metal_1 etching. Where do the charges go?
Aren't they flushed before metal_2 etching?
Or you just want to emphasize that the antenna effect on top metal should be fixed by a protection diode.
Thank you.
 

If during design you missed the antenna rule violation of M1 then it is sure to do some damage to the gate to which it is connected.The charges accumulated during M1 etching are flushed before M2 is etched .

i saw a post where a qeustion was answered when to use a diode and when to use a jumper.Will search and let u know
 

    Ryan1234

    Points: 2
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kapilsn said:
If during design you missed the antenna rule violation of M1 then it is sure to do some damage to the gate to which it is connected.The charges accumulated during M1 etching are flushed before M2 is etched .

i saw a post where a qeustion was answered when to use a diode and when to use a jumper.Will search and let u know
Actually, you had already answered my question. My original question is :
If I using the jumper method to solve the antenna effect on metal_1, that is, I seperate the charges on metal_1 by segmenting metal_1. And it works only during metal_1 etching. If the charges by metal_1 etching aren't be flushed, when metal_2 is fabricated, the charges by metal_1 etching will convene through the jumper, and then the total charges will be the same as unsegmented metal_1. That is what I care about. But you have metioned that the charges accumulated during metal_1 etching are flushed before metal_2 is etched. So it won't be a issue.
Thank your reply.
 

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