• Journal of Surface Science and Engineering
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• v.49 no.3
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• pp.286-300
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• 2016

Pd-Ag alloy membranes have attracted a great deal of attention for their use in hydrogen purification and separation due to their high theoretical permeability, infinite selectivity and chemical compatibility with hydro-carbon containing gas streams. For commercial application, Pd-based membranes for hydrogen purification and separation need not only a high perm-selectivity but also a stable long-term durability. However, it has been difficult to fabricate thin, dense Pd-Ag alloy membranes on a porous stainless steel metal support with surface pores free and a stable diffusion barrier for preventing metallic diffusion from the porous stainless steel support. In this study, thin Pd-Ag alloy membranes were prepared by advanced Pd/Ag/Pd/Ag/Pd multi-layer sputter deposition on the modified porous stainless steel support using rough polishing/$ZrO_2$ powder filling and micro-polishing surface treatment, and following Ag up-filling heat treatment. Because the modified Pd-Ag alloy membranes using rough polishing/$ZrO_2$ powder filling method demonstrate high hydrogen permeability as well as diffusion barrier efficiency, it leads to the performance improvement in hydrogen perm-selectivity. Our membranes, therefore, are expected to be applicable to industrial fields for hydrogen purification and separation owing to enhanced functionality, durability and metal support/Pd alloy film integration.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.65-65
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• 2007

Microstructure and surface roughness of the sensing materials should be improved to use them in advanced sensor applications because the uneven surface roughness degrades the light reflection, pattern resolution, and devices performance. Chemical mechanical polishing (CMP) processing was selected for improving the surface roughness of $CeO_2$ which is one of the well known materials for the oxygen gas sensors. Surface roughness and removal rate of spin coated $CeO_2$ thin films were examined with a change of CMP process parameters such as down force and table speed. The optimized process condition, reflected by the surface roughness with the hillock-free surface as well as the excellent removal rate with the good uniformity, was obtained. The effects of the improved surface roughness on the sensing property of $CeO_2$ thin films were also confirmed. The improved sensitivity of $CeO_2$ thin films for oxygen sensors were obtained after CMP process by the improved surface characteristics. Therefore, we conclude that sensing property of $CeO_2$ thin film is strongly dependent on the surface roughness of $CeO_2$ thin films by using CMP process.

• Tribology and Lubricants
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• v.35 no.5
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• pp.274-285
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• 2019

Chemical mechanical polishing (CMP), which is a material removal process involving chemical surface reactions and mechanical abrasive action, is an essential manufacturing process for obtaining high-quality semiconductor surfaces with ultrahigh precision features. Recent rapid growth in the industries of digital devices and semiconductors has accelerated the demands for processing of various substrate and film materials. In addition, to solve many issues and challenges related to high integration such as micro-defects, non-uniformity, and post-process cleaning, it has become increasingly necessary to approach and understand the processing mechanisms for various substrate materials and abrasive particle behaviors from a tribological point of view. Based on these backgrounds, we review recent CMP R&D trends in this study. We examine experimental and analytical studies with a focus on substrate materials and abrasive particles. For the reduction of micro-scratch generation, understanding the correlation between friction and the generation mechanism by abrasive particle behaviors is critical. Furthermore, the contact stiffness at the wafer-particle (slurry)-pad interface should be carefully considered. Regarding substrate materials, recent research trends and technologies have been introduced that focus on sapphire (${\alpha}$-alumina, $Al_2O_3$), silicon carbide (SiC), and gallium nitride (GaN), which are used for organic light emitting devices. High-speed processing technology that does not generate surface defects should be developed for low-cost production of various substrates. For this purpose, effective methods for reducing and removing surface residues and deformed layers should be explored through tribological approaches. Finally, we present future challenges and issues related to the CMP process from a tribological perspective.

• Analytical Science and Technology
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• v.19 no.5
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• pp.394-399
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• 2006

The polishing performance and the relationships of electrochemistry depending upon oxidizers and additives in the tungsten CMP slurry used in semiconductor industry were investigated. Hydrogen peroxide, ferric nitrate and potassium iodate were used as oxidizers and they showed different oxidation reactions on tungsten film depending on the kind of oxidizers and pH of slurry. The differences influenced the polishing performance. Etching reaction was predominated in the hydrogen peroxide. However, passivation reaction was prevailed in ferric nitrate and potassium iodate. TMAH and KOH raised the potential energy and removal rate of tungsten, and improved a dispersion characteristic of slurry by increasing absolute value of zeta potential. Addition of 100 ppm of poly(acrylic acid) of M.W. 250,000 improved dispersion ability.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1296-1299
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• 2004

MIM capacitor has been investigated for the next generation DRAM. Conventional poly-Si bottom electrode cannot satisfy the requirement of electrical properties and comparability to the high k materials. New bottom electrode material such as ruthenium has been suggested in the fabrication of MIM structure capacitor. However, the ruthenium has to be planarized due to the backend scalability. For the planarization CMP has been widely used in the manufacture of integrated circuit. In this research, ruthenium thin film was Polished by CMP with cerium ammonium nitrate (CAN)base slurry. HNO3 was added on the CAN solution as an additive. In the various concentration of chemical and alumina abrasive, ruthenium surface was etched and polished. After static etching and polishing, etching and removal rate was investigated. Also microroughness of surface was observed by AFM. The etching and removal rate depended on the concentration of CAN, and HNO3 accelerated the etching and polishing of ruthenium. The reasonable removal rate and microroughness of surface was achieved in the 1wt% alumina slurry.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.3
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• pp.213-217
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• 2007

Copper has been used as an interconnect material in the fabrication of semiconductor devices, because of its higher electrical conductivity and superior electro-migration resistance. Chemical mechanical polishing(CMP) technique is required to planarize the overburden Cu film in an interconnect process. Various problems such as dishing, erosion, and delamination are caused by the high pressure and chemical effects in the Cu CMP process. But these problems have to be solved for the fabrication of the next generation semiconductor devices. Therefore, new process which is electro-chemical mechanical polishing(ECMP) or electro-chemical mechanical planarization was introduced to solve the technical difficulties and problems in CMP process. In the ECMP process, Cu ions are dissolved electrochemically by the applying an anodic potential energy on the Cu surface in an electrolyte. And then, Cu complex layer are mechanically removed by the mechanical effects between pad and abrasive. This paper focuses on the manufacturing of ECMP system and its process. ECMP equipment which has better performance and stability was manufactured for the planarization process.

• Transactions on Electrical and Electronic Materials
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• v.6 no.1
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• pp.29-32
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• 2005

Chemical mechanical polishing is an essential process in the production of copper-based chips. On this work, the stability of hydrogen peroxide ($H_{2}O_{2}$) as an oxidizer of copper CMP slurry has been investigated. $H_{2}O_{2}$ is known as the most common oxidizer in copper CMP slurry. But $H_{2}O_{2}$ is so unstable that its stabilization is needed using as an oxidizer. As adding KOH as a pH buffering agent, stability of $H_{2}O_{2}$ decreased. However, $H_{2}O_{2}$ stability in slurry went up with putting in small amount of BTA as a film forming agent. There was no difference of $H_{2}O_{2}$ stability between pH buffering agents KOH and TMAH at similar pH value. Addition of $H_{2}O_{2}$ in slurry in advance of bead milling led to better stability than adding after bead milling. Adding phosphoric acid resulted in the higher stability. Using alumina C as an abrasive was good at stabilizing for $H_{2}O_{2}$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.6
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• pp.515-520
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• 2005

CMP(chemical mechanical polishing) process has been attracted as an essential technology of multi-level interconnection. Also CMP process got into key process for global planarization in the chip manufacturing process. In this study, potentiodynamic polarization was carried out to investigate the influences of $H_2O_2$ concentration and metal oxide formation through the passivation on tungsten and titanium. Fortunately, the electrochemical behaviors of tungsten and titanium are similar, an one may expect. As an experimental result, electrochemical corrosion of the $5\;vol\%\;H_2O_2$ concentration of tungsten and titanium films was higher than the other concentrations. According to the analysis, the oxidation state and microstructure of surface layer were strongly influenced by different oxidizer concentration. Moreover, the oxidation kinetics and resulting chemical state of oxide layer played critical roles in determining the overall CMP performance. Therefore, we conclude that the CMP characteristics tungsten and titanium metal layer including surface roughness were strongly dependent on the amounts of hydrogen peroxide oxidizer.

• Journal of Welding and Joining
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• v.19 no.2
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• pp.191-199
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• 2001

The oxidation and recrystallization behaviors of Ni-base single crystal superalloy, CMSX-2 were investigated to determine the condition of the preparation for transient liquid phase (TLP) bonding operations. The faying surfaces of CMSX-2 were worked by the shot peening, fine cutting and mechanical polishing treatments and the degree of working of treated surfaces was evaluated by the hardness test and X-ray diffraction method CMSX-2 was heat-treated at 1,173∼1.589k for 3.6ks in vacuum of 4mPa. The mechanically polished surface was slightly oxidized after heat treatment even in the vacuum atmosphere of 4mPa. The thickness of an oxide film increased with increasing the heating temperature and the surface roughness of the faying surface. Recrystallization occurred at the surface after heat treatment at above 1,423K when the hardness was increased more than Hv600 by the shot peening treatment while the mechanically polished or fine cut surfaces didn't recrystallized. Based on these results, it was clearfied that the mechanically polishing with fine abrasive grit could be used for the preparation of faying surface of CMSX-2 before bonding operation.

• Transactions of Materials Processing
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• v.13 no.3
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• pp.225-229
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• 2004

Chemical Mechanical Polishing(CMP) process becomes one of the most important semiconductor processes. But the basic mechanism of CMP still does not established. Slurry fluid dynamics that there is a slurry film between a wafer and a pad and contact mechanics that a wafer and a pad contact directly are the two main studies for CMP. This paper based on the latter one, especially on the abrasion wear model. Material Removal Rate(MRR) is calculated using the trajectory length of every point on a wafer during the process time. Both the rotational velocity of a wafer and a pad and the wafer oscillation velocity which has omitted in other studies are considered. For the purpose of the verification of our simulation, we used the experimental results of S.H.Li et al. The simulation results show that the tendency of the calculated MRR using the relative velocity is very similar to the experimental results and that the oscillation effect on MRR at a real CMP condition is lower than 1.5%, which is higher than the relative velocity effect of wafer, and that the velocity factor. not the velocity itself, should be taken into consideration in the CMP wear model.