Effect of Nano-Scale Hindrance-Layer of Amine-Functional Organic Polymer on Self-Stop Chemical Mechanical Planarization

Abstract

As semiconductors become more integrated, structures become increasingly complex. Currently, various innovative devices of 3D are emerging. In this trend, Chemical Mechanical Planarization (CMP) spends a lot of time and money. If the cost of consumables such as CMP slurry is reduced, there is an advantage of increasing productivity and reducing process steps. In this case, Self-stop Slurry can lead to savings in time and consumables as the semiconductor CMP process changes from 2-step (High-Removal → High-Selectivity) to 1-step. In other words, one type of slurry must produce a variety of polishing rates according to the wafer condition. In this paper, through CMP slurry engineering, a method to improve the existing self-stop CMP by creating a nano-scale interference film using a cationic organic polymer having an amine group is presented. Self-Stop CMP slurries must have a sufficient polishing rate to remove steps, and furthermore, global planarization must not occur after all steps are removed. To achieve the goal, the blanket polishing was delayed by adsorbing through the concentration optimization of Diethylenetriamine, Polyallylamine hydrochloride, Poly-diallyl dimethylammonium chloride, and Polyethyleneimine, which are organic cationic polymers with amine groups on the film. On the contrary, the hindrance-layer was made meaningless with sufficient pressure, and the step was set to be polished. Adsorption tests (Zeta potential, UV-vis) and surface analysis (Ellipsometer, TEM) were performed to confirm the effect of each cationic polymer agent on the adsorption rate and removal rate. We have tried to find out what mechanisms of ceria-based slurries with polymer agent will act on the polishing and film condition. The self-stop agent was added to create a high-performance slurry with a blanket polishing rate of less than 10 nm/min and a step polishing rate of 300 nm/min. The step-removing self-stop slurry designed in this paper is expected to be helpful in the next-generation semiconductor process.