Minimizing ECO routing for FIB

Abstract

Engineering Change Order (ECO) routing is often requested in later design stages even after chip manufacturing. We propose an ECO routing method that can reuse most existing routing pattern to implement the modifications. In current industrial design methodologies, designers often take advantage of FIB (Focused Ion Beam) process when they need functional changes and/or bug fixings as soon as possible after chip manufacturing. Therefore, we apply our method to do circuit modifications in the FIB system, which is commonly used to slightly modify an existing circuit by cutting unwanted electrical connections and depositing conductive material to make a connection. However the exact coordinates on the circuit are necessary before using the FIB system, because the FIB system cuts and re-wires connections according to the given coordinates, and those FIB locations must be conformed to pre-specified conditions and follow certain guidelines. As design complexity increases rapidly, ECO routing in designs with high metal density becomes more and more difficult, and the successful rate is becoming lower. The ECO routing method we proposed can effectively apply to the FIB system for finding the layout locations and using the minimum FIB processes, which leads to successful FIB results.