Recently, the demand for the miniaturization of package substrate has been increasing. Technical innovation of package substrate manufacturers steps into CMP(chemical mechanical planarization) applications. Electroplated copper filled in trenches on substrate needs to be planarized for multi-level wires less than 10㎛. In the existing wiring, it was possible to remove unnecessary copper from substrate surface only through etching process, but now if etching process adopted, as more line width reduced, as more defects are occuring. As package substrate is Cu hybrid structure through the repeated Cu plating and removing process on CCL(copper clad lamination) substrate, it became more recently necessary to apply CMP technology to remove unnecessary copper from substrate surface.
The CMP process is material removal in the form of thin film with the relation motion between material and pad. Also known as CMP, is now widely recognized as the technology of choice or eliminating topographic variations and achieving near-perfect planarity of interconnection and metal layers in ultra large scale integrated(ULSI) devices.
This paper introduces CMP process as a new package substrate manufacturing step. The purpose of this study is to investigate an effect of surfactant and pad properties on dishing and erosion of Cu patterns with the line and space of around 10/10㎛ used for the advanced package substrate. The conventional Cu slurry without surfactant had problems including severe erosion of 0.58㎛ in Cu patterns smaller than 4/6㎛ and deep dishing of 4.2㎛ in Cu patterns larger than 14/16㎛. However, experimental results showed that the friction force during Cu CMP changed to lower value, and the dishing and erosion became smaller simultaneously as the surfactant concentration became higher. Finally, more globally planarized Cu patterns could be realized with erosion range of 0.22㎛ to 0.35㎛ and, dishing range of 0.37㎛ to 0.69㎛ respectively by using 3wt% concentration of surfactant. In addition, it was confirmed that dishing and erosion amount varies depending on alteration of pad properties. Viscoelastic and hardness of pad were minimized erosion amount in package substrate CMP.