Reduction of the Maximum Step Height on a Package Substrate by the Optimization of Slurry Chemical Additives

摘要

Package substrates have accompanied the development of the semiconductor industry. Advanced package substrate technology is being studied to carry many demanding functions. A re-distribution layer is the most important factor in developing this technology and achieving planarization of the top layer of lower substrate is important for this goal. The substrate is made of copper and an insulating polymer. Control of the pattern step height of copper and the polymer requires consideration of the mechanism of each material. In this experiment, since the polymer has little chemical polishing effect, the polishing rate of copper is controlled to reduce the step height by adjusting the chemical additives in the slurry. The chemical additives were an oxidizer, a complexing agent, and a corrosion inhibitor, which were applied to two different pattern sizes in order to compare the step height. The oxidizer and complexing agent promoted the chemical reaction of the copper, and the corrosion inhibitor suppressed the chemical reaction of the copper. In this experiment, it was confirmed that the larger the pattern size, the more chemical reaction was required. In the multi-sized pattern substrate, the overall planarization can be achieved by adjusting the maximum step height of each pattern.