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Approaches to Sustainability in Chemical Mechanical Polishing (CMP): A review
Hyunseop Lee,Hyoungjae Kim,Haedo Jeong 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.9 No.1
Chemical mechanical polishing (CMP) is an essential planarization process for semiconductor manufacturing. The application of CMP has been increasing in semiconductor fabrication for highly integrated devices. Recently, environmental burden caused by the CMP process was assessed because of interest in the global environment. In this study, the previously reported impacts of CMP on the environment and studies conducted on developing various methods to reduce environmental burden are reviewed. In addition to analyzing the impacts of CMP, this paper introduces a method for treating CMP wastewater and improving the material removal efficiency through the improvement of CMP consumables. Finally, the authors review research on hybridization of the CMP process and discuss the direction in which CMP technology will progress to improve sustainability in the future.
Preliminary Study on the Effect of Spray Slurry Nozzle in CMP for Environmental Sustainability
Lee, Hyunseop,Park, Yeongbong,Lee, Sangjik,Jeong, Haedo 한국정밀공학회 2014 International Journal of Precision Engineering and Vol.15 No.6
In chemical mechanical planarization (CMP) industry, reducing slurry consumption without avoiding the drop in productivity is one of the most important requirements for environmental sustainability. In this paper, we propose a spray slurry nozzle to reduce the slurry consumption and increase the material removal rate (MRR) in $SiO_2$ CMP. The spray slurry nozzle is compared with a commonly used tube-type slurry nozzle in terms of MRR, material removal uniformity, friction force, and process temperature. And, a case study on the greenhouse gas (GHG) emission associated with the slurry consumption is provided by polishing patterned wafers. Adopting the spray slurry nozzle in CMP process provides higher MRR, higher friction force, and shorter process time than the normal tubetype slurry nozzle. Thus, the spray slurry nozzle will diminish the carbon dioxide equivalent (CDE) associated with the slurry and electricity consumptions. Furthermore, using the spray nozzle decreases the process temperature and it may be used as a cooling system for the CMP process.
Mechanical effect of colloidal silica in copper chemical mechanical planarization
Lee, Hyunseop,Joo, Sukbae,Jeong, Haedo Elsevier 2009 Journal of materials processing technology Vol.209 No.20
<P><B>Abstract</B></P><P>The mechanical effect of colloidal silica concentration in copper chemical mechanical planarization (CMP) is considered in this paper by using friction force monitoring system. The copper peak was detected in the result of the energy-dispersive X-ray (EDX) spectra of the polishing residues. The addition of colloidal silica into copper CMP slurry increased both the material removal rate and the friction force. During CMP, as the concentration of the colloidal silica was increased, the temperature generated by the friction force also increased. To understand effect of abrasive concentration on the material removal and friction force, we considered the material removal and the friction energy for a single abrasive. The surface of the polished copper film was measured by X-ray photoelectron spectroscopy (XPS). All the material removal rates as a function of friction energy after polishing with various concentrations of colloidal silica had a non-linear characteristic.</P>
Lee, Hyunseop,Kim, Chongyoup Elsevier 2018 Colloids and surfaces. A, Physicochemical and engi Vol.548 No.-
<P><B>Abstract</B></P> <P>In this study the reversible aggregation and breakage of two dimensional (2D) flocs in the bulk phase are investigated experimentally in a suspension of platelike particles under a torsional flow between two parallel plates. The suspension was prepared by dispersing platelike particles in a Newtonian fluid. The Newtonian fluid has a viscosity of 1.27 Pa s and the average dimension of the particle face is approximately 1 μm with a thickness of 250 nm. Peclet number of the particle is over 100 and the aggregation is orthokinetic. The microstructure was examined under an optical microscope without disturbing the flow or particle motions. The result shows that 2D flocs of fractal types with the aspect ratio of over 20 between the average face diameter and thickness are formed in the bulk phase by the aggregation of platelike particles and the face of the planar floc is oriented in the same direction of the velocity gradient. The flocs have non-circular faces with size dependent fractal dimensions. The flocs tend to be oriented along the vorticity or the flow direction depending on shear rate and the orientation strongly affects floc breakage and floc size. The breakup of flocs occurs mostly at the middle of the floc after being aligned along the flow direction.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Surface Activation by Electrolytically Ionized Slurry during Cu CMP
Lee, Dasol,Lee, Hyunseop,Jeong, Seonho,Yuh, Minjong,Jeong, Haedo The Electrochemical Society 2019 ECS journal of solid state science and technology Vol.8 No.5
<P>In semiconductor chip fabrication, flatness of the layer is vital, and is achieved by chemical mechanical planarization (CMP). Slurry determines mechanisms for removal, and therefore accounts for the most expense in CMP. However, conventional slurry supply systems lead to wastage of the slurry not used in polishing. Therefore, this study proposes a new slurry supply method using ionization of slurry by electrolysis. Applying an electric force to the slurry may significantly reduce slurry consumption in the CMP process. First, stainless steel was selected as a suitable electrode for the system through a simple experiment. With this system, the material removal rate was evaluated according to the applied voltage and compared to that in the conventional method under different slurry flow rates. The removal mechanism of the ionized slurry was investigated by UV-visible spectroscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. The band intensities of the intramolecular bonding structures and amounts of oxygen and Cu oxide on the surface were different depending on the electrolysis in the slurry. Accordingly, the effect of the ion-rich slurry was verified. This method is promising for efficient slurry supply systems in CMP applications as well as other manufacturing processes.</P>
Lee, Hyunseop Korean Tribology Society 2018 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.34 No.6
Copper chemical mechanical planarization (CMP) has become a key process in integrated circuit (IC) technology. The results of copper CMP depend not only on the mechanical abrasion, but also on the slurry chemistry. The slurry used for Cu CMP is known to have greater chemical reactivity than mechanical material removal. The Cu CMP slurry is composed of abrasive particles, an oxidizing agent, a complexing agent, and a corrosion inhibitor. Citric acid can be used as the complexing agent in Cu CMP slurries, and is widely used for post-CMP cleaning. Although many studies have investigated the effect of citric acid on Cu CMP, no studies have yet been conducted on the interfacial friction characteristics and step height reduction in CMP patterns. In this study, the effect of citric acid on the friction characteristics and step height reduction in a copper wafer with varying pattern densities during CMP are investigated. The prepared slurry consists of citric acid ($C_6H_8O_7$), hydrogen peroxide ($H_2O_2$), and colloidal silica. The friction force is found to depend on the concentration of citric acid in the copper CMP slurry. The step heights of the patterns decrease rapidly with decreasing citric acid concentration in the copper CMP slurry. The step height of the copper pattern decreases more slowly in high-density regions than in low-density regions.