• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.107-108
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• 2006

In this work, we first applied the chemical mechanical polishing (CMP) process to the planarization of ferroelectric film in order to obtain a good planarity of electrode/ferroelectric film interface. $Bi_{3.25}La_{0.75}Ti_{3}O_{12}$ (BLT) ferroelectric film was fabricated by the sol-gel method. However, there have been serious problems in CMP in terms of repeatability and defects in patterned wafer. Especially, dishing & erosion defects increase the resistance because they decrease the interconnect section area, and ultimately reduce the lifetime of the semiconductor. Cross-sections of the wafer before and after CMP were examined by Scanning electron microscope(SEM). Process characteristics of non-dishing and erosion were investigated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.77-78
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• 2006

We fabricated photonic crystals on GaAs and GaN substrates. After anodizing the aluminium thin film in electrochemical embient, the porous alumina was implemented to the mask for reactive ion beam etching process of GaAs wafer. And photonic crystals in GaN wafer were also fabricated using electron beam nano-lithography process. The coated PMMA thin film with 200 nm-thickness on GaN surface was patterned with triangular lattice and etched out the GaN surface by the inductively coupled plasma source. The fabricated GaAs and GaN photonic crystals provide the enhanced intensities of light emission for the wavelengths of 858 and 450 nm, respectively. We will present the detailed dimensions of photonic crystals from SEM and AFM measurements.

• KSTLE International Journal
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• v.6 no.2
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• pp.33-38
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• 2005

Submicron-scale patterns made of polymethyl methacrylate (PMMA) were fabricated on silicon-wafer using a capillarity-directed soft lithographic technique. Polyurethane acrylate (PUA) stamps (Master molds) were used to fabricate the patterns. Patterns with three different aspect ratios were fabricated by varying the holding time. The patterns fabricated were the negative replica of the master mold. The patterns so obtained were investigated for their adhesion and friction properties at nano-scale using AFM. Friction tests were conducted in the range of 0-80 nN. Glass (Borosilicate) balls of diameter 1.25 mm mounted on cantilever (Contact Mode type NPS) were used as tips. Further, micro-friction tests were performed using a ball-on-flat type micro-tribe tester, under reciprocating motion, using a soda lime ball (1 mm diameter) under a normal load of 3,000 mN. All experiments were conducted at ambient temperature ($24{\pm}1^{\circ}C$) and relative humidity ($45{\pm}5\%$). Results showed that the patterned samples exhibited superior tribological properties when compared to the silicon wafer and non-patterned sample (PMMA thin film) both at the nano and micro-scales, owing to their increased hydrophobicity and reduced real area of contact. In the case of patterns it was observed that their morphology (shape factor and size factor) was decisive in defining the real area of contact.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.366-369
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• 2003

The vertical fountain plating system with the point contact has been used in semiconductor industry. But the plating shape in the opening of photoresist becomes gradated shape, because bubbles from the wafer surface are difficult to escape from the deep openings, vias. So, we designed the tilted electrode ring contact to get uniform bump height on all over the wafer and evaluated the film uniformity by SEM and $\alpha$-step. A photoresist was coated to a thickness of $60{\mu}m$ and vias were patterned by a contact aligner After via opening, solder layer was electroplated using the fountain plating system and the tilted electrode ring contact system. In $\alpha$-step measurement, film uniformities in the fountain plating system and the tilted electrode ring contact system were ${\pm}16%,\;{\pm}3.7%$ respectively. In this study, we could get high uniformity bumps by the tilted electrode ring contact system. So, tilted electrode ring contact system is expected to improve workability and yield in module process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.881-885
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• 2004

We report a method for making a device on which semi-conducting single-walled carbon nanotubes are attached selectively between two metal electrodes. This method is divided two processes. First we can connect a rope of single-walled carbon nanotubes(SWNTs) between two electrodes using the electric field. But a SWNTs' rope obtained by the first process was composed of a few of metallic and semi-conducting SWNTs together. The second process is to burn the metallic and semi-conducting nanotubes through applying a voltage. As a result, we can obtain a semi-conducting SWNT device. To make the patterned electrodes, we deposited $SiO_2$(150nm) on a wafer. After then, we made a patterned samples with Ti(200 $\AA$)/Au(300$\AA$). We empirically obtained a electric condition 0.66 $V_{pp}$ /${\mu}{\textrm}{m}$@5MHz. From this result, we verified that most of current go through the metallic nanotubes in this device. When we apply DC voltage between two electrodes, the metallic carbon nanotubes are burnt. Finally, we can obtain a semi-conducting nanotube device which we desire to make. We got the I-V characteristic graph which has shown the semi-conducting property. We hope to apply to the various applications using this selective semi-conducting carbon nanotube deposition method.ethod.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.239-239
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• 2003

As a result of the recent miniaturization and enhancement in the performance of thin film inductors and thin film transformers, there are increased demands for the thin films with a high magnetic permeability in the high frequency range, a high saturation magnetization, a high electrical resistivity, and a low coercive force. In order to improve high frequency properties, we will investigate anisotropy field by shape and size of pattern. The Fe-Al-O thin films of 16mm diameter and 1$\mu\textrm{m}$ thickness were deposited on Si wafer, using RE magnetron reactive sputtering technique with the mixture of argon and oxygen gases. The fabricating conditions are obtained in the working partial pressure of 2m Torr, O$_2$ partial Pressure of 5%, Input power of 400w, and Al pellets on an Fe disk with purity of 99.9%. For continuous thin film is the 4Ms of 19.4kG, H$\sub$c/ of 0.6Oe, H$\sub$k/ of 6.0Oe and effective permeability of 2500 up to 100MHz. In this work, we expect to enhanced effect of magnetic anisotropy on patterned of Fe-Al-O thin films.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1825-1828
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• 2008

A simple method for the fabrication of porous nano-master for antireflective surface is presented. In conventional fabrication methods for antireflective surface, coating method with low refractive index has usually been used. However, it is required to have high cost and long times for mass production. In this paper, we suggested the fabrication method of antireflective surface by the hot embossing process using the porous nano patterned master on silicon wafer fabricated by low-temperature anodic aluminum oxidation. Through multi-AAO and etching processes, nano patterned master with high aspect ratio was fabricated at the large area. Pore diameter and inter-pore distance are about 150nm and from 150 to 200nm. In order to replicate anti-reflective structure, hot embossing process was performed by varying the processing parameters such as temperature, pressure and embossing time etc. Finally, antireflective surface can be successfully obtained after etching process to remove selectively silicon layer of AAO master.

• Korean Journal of Materials Research
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• v.19 no.3
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• pp.174-178
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• 2009

The effects of post-CMP cleaning on the chemical and galvanic corrosion of copper (Cu) and titanium (Ti) were studied in patterned silicon (Si) wafers. First, variation of the corrosion rate was investigated as a function of the concentration of citric acid that was included in both the CMP slurry and the post-CMP solution. The open circuit potential (OCP) of Cu decreased as the citric acid concentration increased. In contrast with Cu, the OCP of titanium (Ti) increased as this concentration increased. The gap in the OCP between Cu and Ti increased as citric acid concentration increased, which increased the galvanic corrosion rate between Cu and Ti. The corrosion rates of Cu showed a linear relationship with the concentrations of citric acid. Second, the effect of Triton X-$100^{(R)}$, a nonionic surfactant, in a post-CMP solution on the electrochemical characteristics of the specimens was also investigated. The OCP of Cu decreased as the surfactant concentration increased. In contrast with Cu, the OCP of Ti increased greatly as this concentration increased. Given that Triton X-$100^{(R)}$ changes its micelle structure according to its concentration in the solution, the corrosion rate of each concentration was tested.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.561-562
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• 2006

The purpose of this study was to investigate the root cause of adhesion of silica and ceria particles during Poly-Si, TEOS, and SiN CMP process, respectively. The zeta-potentials of abrasive particles and wafers were observed negative surface charges in the alkaline solutions. SAC and STI patterned wafers have intermediate values of their composition surface's zeta potentials. The theoretical interaction force and adhesion force of silica and ceria particle were calculated in solution with acidic, neutral and alkaline pH. A stronger attractive force was calculated for silica and ceria particles on wafers in acidic solutions than in alkaline solutions. The theoretical interaction forces of the SAC and STI patterned wafers have intermediate values of their constitution wafer's values. The adhesion forces is observed lower values in alkaline solutions than in acidic solutions. And the ceria particle has lower adhesion than that of the silica particle.

• Proceedings of the Korean Magnestics Society Conference
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• 2003.06a
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• pp.194-194
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• 2003

As a result of the recent miniaturization an enhancement in the performance of thin film inductors and thin film transformers, there are increased demands for the thin films with high magnetic permeability in the high frequency range, high saturation magnetization, in high electrical resistivity, and low coercive force. In order to improve high frequency properties, we will investigate anisotropy field by shape and size of pattern. The Fe-Al-O thin films of 16mm and 1 $\mu\textrm{m}$ thickness were deposited on Si wafer, using RF magnetron reactive sputtering technique with the mixture of argon and oxygen gases. The fabricating conditions are obtained in the working partial pressure of 2mTorr, O$_2$ partial pressure of 5%, input power of 400W, and Al pellets on an Fe disk with purity of 99,9%. Magnetic properties of the continuous films as followed: the 4$\pi$M$\_$s/ of 19.4kG, H$\_$c/ of 0.6Oe, H$\_$k/ of 6.0Oe and effective permeability of 2500 up to 100㎒ were obtained. In this work, we expect to enhance effect of magnetic anisotropy on patterned of Fe-Al-O thin films.