Semiconductors

136 Semiconductors: Integrated Circuit Design for Manufacturability

Placement of an IP block in the die may create pattern density gradients,

and a global addition of ll features (wafes) is required, typically using one

or more of the three main approaches (Table3.17) developed for different

product generations.

There are several critical parameters of the dummy ll and the resulting

pattern density distribution it ensures (Table3.18).

Adding dummy structures should level out pattern density among the indi-

vidual blocks in the die, but different die regions may require different ll

(Figure3.28). Sparse wafing may adjust pattern density ...