Metals Protruding Through Two or More Dielectric Layers

A side view of a circuit with three 50 mil dielectric layers (A, B, and C) and a 75 mil thick metal polygon on level 2 is shown below. Note that the top of the metal is physically located midway through dielectric layer A.

It is important to note that under these circumstances the Sonnet analysis engine em will automatically add an additional sheet (for Thick Metal Model or Rough Metal) or an additional layer (for TrueVolume) at the junction between dielectric layers A and B.  Hence, the 2-sheet Thick Metal Model or Rough Metal models would be simulated with 3 sheets. The Single Layer Surface TrueVolume model, which normally requires 3 layers, would now require 4 layers.

It should be noted that physically thick metals may also traverse multiple dielectric layers. In this case, an additional sheet or layer is added to the metal model at each dielectric layer junction which the metal traverses.

Any additional sheets and/or layers which are added automatically by em for protruding metals will result in increased memory usage and simulation time.