Re: filler vs spare cells
Hi,
Filler cells are the basic cells used to make well continuity, mostly they doesn't contain any functionality. While spare cells are the extra functional cells kept in the design for ECO (Engg. change order). The number of sparecells and their type i.e. AND, OR, DFF ect. depends on the design complexity and functionality, but it is advisable to use universal gates so that we can get most of the functionality.
It may help you.
Thanks..
HAK..