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impact on current with change in metal thickness? (Read 5309 times)

sirous black New Member Offline Posts: 4	impact on current with change in metal thickness? Apr 25^th, 2008, 5:31am On changing a given metal from 2XTM to 1XTM, what is the impact on current? I understand that there is a change in resistance, and hence overall IR drop, but current benig a surface phenomena wouldnt be affected. Correct me if my assumption is wrong.
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loose-electron Senior Fellow Offline Best Design Tool = Capable Designers Posts: 1638 San Diego California	Re: impact on current with change in metal thickne Reply #1 - May 14^th, 2008, 4:10pm please explain with more detail what you are looking for
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CMOSSolutions New Member Offline Posts: 2	Re: impact on current with change in metal thickne Reply #2 - May 29^th, 2008, 9:25am Is this a large mixed signal SOC? For large designs the IR drop in power distribution is pretty much DC to daylight, so thinner metal will affect the IR drop. Also check the current density and EM limits for your specific process. Hints about the type of design, frequency and process info would help.
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Maks

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Re: impact on current with change in metal thickness?
Reply #3 - Apr 25^th, 2010, 12:26pm

sirous black wrote on Apr 25^th, 2008, 5:31am:

On changing a given metal from 2XTM to 1XTM, what is the impact on current? I understand that there is a change in resistance, and hence overall IR drop, but current benig a surface phenomena wouldnt be affected.

Correct me if my assumption is wrong.

Depending on the design of the power FET (metal resistivities, device resistance, layout shapes, metal strapping, etc.) changing metal thickness or resistance may or may not affect the total resistance and the pattern of the current flow. One needs to run simulations of the device + metals+ vias + wirebonds to understand the impact of an individual metal layer resistivity on the total Rdson value. See attached plot for an example of such simulations - the plot shows the current density distribution in the top metal layer of a three-metal-layer power MOSEFT design.

Current_density_in_power_transistor_top_metal_layer.png

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