Planarization yield limiters for wafer-scale 3D ICs
The planarization requirements for 3D processing are compared to those for conventional 2D processing, indicating that wafer level planarity is essential for 3D as compared to the die level planarity needed for 2D ICs. A yield test structure has been designed to study the number of electrical faults that occur during damascene patterning. Initial experimental data with this test vehicle show that planarity changes with pattern density, although the functional relationship has not been established to date.