To follow the Moore's law, the advanced Cu slurry needs to continue the trend of cost reduction and performance improvement at the same time. With the technology node shrinking, there is a need to develop a Cu slurry with fast rate for high throughput and low dishing for minimal within die and within wafer variation, and stringent defect requirement such as residue, corrosion, and micro scratches. In this paper, we introduce a high performance Cu CMP slurry to overcome these performance challenges in Cu CMP process. The impact of slurry formulation on the slurry performance will be presented under different process conditions, including blanket removal rates/profiles, static etch rates, dishing, Cu residue clearance capability and corrosion status. Electrochemical study was also conducted to support the results and performance. With the optimized formulation and polishing process, the slurry achieves dishing under 300A at near 1 um Cu polishing rate. For multiple layers stacking, the slurry also has tunable dishing to provide a wide process integration window.

With the application of Ultra low-k dielectric material in the advanced nodes, more and more challenges are elevated on barrier CMP. High removal rates of TEOS and barrier films are required to enable an effective removal, while tunable Cu RR and low ULK RR are needed to control the topography and stop in ULK layer. The k value shift of polished ULK also should be minimized. In this paper, we will report a barrier slurry for this application including slurry additives effect on removal rate selectivity, topography and k value. The corrosion control capability is also evaluated by soaking test. Through slurry formulation tuning, an optimal topography with good within wafer and within die non-uniformity are obtained. The control capability in removal rate and selectivity, k value shift of polished ULK, topography, and Cu corrosion were demonstrated.

With the development of the products with more advanced technology nodes, new challenges continue to emerge in CMP processes. For example, there is a strong need to use lower down force in polishing process while maintaining a high removal rate to avoid low-k/ultra-low k dielectric film damage. The requirements for dishing, overpolish window, Cu residue clearance capability and surface defectivity, especially corrosion related defects become more stringent as copper lines become narrower and narrower. In this paper, we share our research efforts and results in developing a novel copper CMP slurry to overcome these performance challenges in Cu CMP process. In short, a well designed inhibitor system was applied in this slurry. The impacts of these inhibitors on the slurry performance including blanket removal rate/profile, static etch rate, dishing, Cu residue clearance capability and corrosion were evaluated through polishing experiments, electrochemistry evaluations, and laboratory tests simulating CMP aggressive conditions. With a synergetic effect of these inhibition systems, the slurry shows the excellent CMP performance

Chemical mechanical planarization (CMP) of copper is a critical step in advanced IC interconnects technology. The key performance metrics of a Cu CMP are the removal rate, removal rate profile, dishing and erosion, process window, and defectivity. Many researchers have studied the mechanisms of Cu CMP. The present investigations will mainly focus on the mechanical effects on advanced Cu CMP at low down forces. The two main mechanical factors, intrinsic properties of abrasives and polishing process conditions, were evaluated. It was found that the abrasive properties such as mean size, surface area, solid concentration and process conditions such as polishing down force and rotation speed have strong impacts on Cu CMP performance.

Chemical mechanical planarization (CMP) is a critical technology for the copper damascene process. With the development of more advanced technology nodes, New challenges have emerged for the conventional CMP processes--the need for using lower down force while maintaining removal rate to avoid low-k/ultra-low k dielectric film damage and wide over polishing window. Also, surface defects especially corrosion related defects become more stringent as copper line becomes narrower and narrower. In this paper, we share our current efforts and associated results to develop the novel copper slurry for such CMP process. The slurries with different organic additives were evaluated for removal rate, dishing rate, electrochemical analysis and anti-corrosion capability. Based on these results, a novel copper slurry has been developed and it shows the excellent CMP performance.