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Design >> Analog Design >> FIB operation on a 1GHz signal
https://designers-guide.org/forum/YaBB.pl?num=1224257908

Message started by neoflash on Oct 17^th, 2008, 8:38am

Title: FIB operation on a 1GHz signal
Post by neoflash on Oct 17^th, 2008, 8:38am

Hi,

Recently I have been debugging a design on 0.13um process.

One bug requires cutting and reconnecting (12um) a signal running at 1-2 GHz. This signal is on a timing path.

I would like to know more about the potential impact of FIB operation on the performance of propagation delay?

Thanks,
Neo

Title: Re: FIB operation on a 1GHz signal
Post by rf-design on Oct 17^th, 2008, 10:55am

The FIB have a specific sheet resistance which is in between metal and poly. So the RC-delay impact increases.

Title: Re: FIB operation on a 1GHz signal
Post by Paul on Nov 11^th, 2008, 1:10pm

Hi Neo,

Conducting material is usually platinum or tungsten, the latter being 2x less resistive, though still 3x more than Cu. Notice the deposition for longer stripes is done in several steps, which again increases resistivity.

I am a designer, not a FIB guy, but I would guess that at best you might get some samples operating at the desired speed, but the FIB yield at these frequencies might not be tremendous. At least, talk to your FIB guys before proceeding, they should know better what you can expect based on the actual case (how deep do they have to mill before getting to the desired wire, how large is the wire to contact, etc...).

This might not be critical to you, but FIB usually also comes with some leakage in the milling region.

Regards
Paul