WELL Isolation Methodology for Power Domain Independent Implementation
In any physical design implementation with multiple power domains, the power connections to the standard cells are constrained by the physical placement of the cells in the respective power domains. Any change to the power connectivity of a standard cell, after the design has been taped out, requires changes in base layers which are quite costly. This limitation requires a full mask revision independent of the fact that other functional changes may just be possible in selective metal layers only. The paper discusses this challenge at length and a sequence of steps is proposed to overcome this limitation.