Increase the removal rate of Cu at CMP
Conclusion: Winning Solution
The model shows that increasing H₂O₂ concentration alone cannot continuously increase the Cu removal rate. At high peroxide concentration, copper is oxidized rapidly and a thick, continuous Cu₂O/CuO layer forms. Because this oxide occupies about 1.7–1.8 times the volume of the consumed copper, it grows quickly, passivates the surface, and becomes the new barrier to removal.
The winning solution is therefore to balance chemical oxidation with mechanical removal. When the oxidation rate is increased, the mechanical part of the CMP process must also be strengthened. This can be achieved by increasing pad speed, optimizing pressure, increasing abrasive-particle concentration, or improving pad conditioning and slurry transport.
The key principle is:
Do not increase only the oxidation rate. Increase the capacity to remove the oxide at the same time.
A higher H₂O₂ concentration is useful only when the pad, abrasives, and process conditions can remove the oxide layer at a matching rate. The most effective solution is not the maximum peroxide concentration, but the optimum combination of chemical oxidation and mechanical oxide removal.
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