sirous black wrote on Apr 25th, 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.