The effect of slurry flow rate, pad surface temperature, and temperature during the pad conditioning process on surface tribology and pattern-related defects like dishing, erosion, and metal loss was studied. Experimental results suggest that dishing and erosion levels decreased with increase in slurry flow rate. Conditioning experiments at various temperatures revealed a significant impact of temperature on the effectiveness of the conditioning process and also on subsequent polishing performance. The polishing pad was conditioned more aggressively at lower temperatures compared to conditioning at elevated temperatures. The removal rate and coefficient of friction were found to be significantly affected by the pad surface temperature. The amount of dishing increased with increase in pad surface temperature and the uniformity of polishing. The study ascertains a correlation between process parameters and the extent of planarity defects. This study also demonstrates the use of a modified bench-top chemical mechanical polish ͑CMP͒ tester and large-stage atomic force microscope with automatic multiscan imaging procedure.Copper chemical mechanical polishing ͑CMP͒ is being widely researched to better understand and improve the damascene process of integrated circuit ͑IC͒ fabrication. Due to the pattern density variations across the wafer, there is a difference in individual removal rates and step height reductions of patterns mainly depending on the density and width of the pattern lines. Due to this inconsistent removal rate, global planarization faces issues like nonuniformity within a single die subsequently leading to defects like dishing and erosion of the interconnect materials. Dishing and erosion account for a major portion of the yield losses during manufacturing. Dishing is the loss of the copper from the copper lines, resulting in a deviation from the desired flatness of the metallization layer. 1,2 Erosion is the loss of dielectric material due to its removal during the overpolishing step ͑practiced in order to remove even the final trace of copper between the metal lines͒. There are many factors that influence the generation of these anomalies on the surface. Some such factors are width of the lines, pattern density, down force, and physical properties of the polishing pads. Even though models and investigations have been done in the past 3-5 to investigate the effect of down force, slurry chemistry, and pattern dependencies, little effort has been put into studying in depth the sources of generation of dishing and erosion. In the current study, the effects of slurry flow rate, polishing pad temperature at the interface, and pad conditioning on dishing, erosion, and metal loss are being studied. The slurry being delivered at the interface of the pad and wafer contact takes away a major part of the heat from the interface through convective heat transfer. 6-9 The amount of heat dissipated at the interface is crucial in the process of CMP. Heat dissipated is found to impact the removal rate due to the chang...
The effects of different process parameters on tribology and surface defects were studied till date, but there has been minimal study to understand the effect of temperature on the copper chemical mechanical polishing ͑CMP͒ process. The effect of temperature on tribology and surface defects during copper CMP employing different pad materials and slurries has been explored. From the results, it was seen that the coefficient of friction and removal rate increased with an increase in slurry temperature during polishing. The experimental data indicated that the increase in temperature results in an increase in amounts of metal dishing and metal loss. The dishing and metal loss in the interconnect features initially increased with an increase in temperature and then decreased at elevated temperatures. With an increase in temperature the copper films peeled off from the wafer due to low adhesion with low-k dielectric material at higher temperatures. The electrical properties of the planarized devices showed drastic degradation with increase in dishing values. Also the temperature showed a significant effect on pad physical and mechanical properties with an increase in temperature. The increase in temperature also increased the crystallinity of the copper film.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.