Gwon-Woo Choi

Removal characteristics of hillock on SnO2 thin film by chemical mechanical polishing process

SnO2 is one of the most suitable materials for gas sensors. The microstructure and surface morphology of SnO2 films must be controlled because the electrical and optical properties of SnO2 films depend on these characteristics. We investigated the effects of chemical mechanical polishing (CMP) on the variation of morphology of SnO2 films prepared by rf sputtering system. The commercially developed ceria-based oxide slurry, silica-based oxide slurry, and alumina-based tungsten slurry were used as CMP slurry. Nonuniformities of all slurries coincided with stability standards of less than 5%. Silica slurry had the highest removal rate among three different slurries. In addition, the particle size analysis showed that silica slurry had an abrasive with the largest average particle size of the three. Based on the atomic force microscopy analysis of thin film topographies and root mean square values, silica slurry has excellent properties that allow the application of SnO2 thin films as gas sensor materials.

Effects of various oxidizers on chemical mechanical polishing performance of nickel for microelectromechanical system applications

Nickel and nickel-based alloys are known candidates to realize movable structures for microelectromechanical system (MEMS) application. Chemical mechanical polishing (CMP) has found extensive application in the fabrication of MEMS. In this study, the CMP of nickel was performed using the commercial slurry with the various ratios of different oxidizers and alumina particle as an abrasive. Moreover, the potentiodynamic polarization behaviors were discussed to evaluate the effects of nickel-CMP performance and electrochemical characteristics between nickel and the various oxidizers. As an experimental result, the removal rate of nickel reached a maximum at 1.0vol% of H2O2 concentration. An addition of 5.0wt% alumina (Al2O3) abrasive could improve the removal rate of nickel; however, many scratches were observed. For the case of Fe(NO3)3 addition as an oxidizer, both the removal rate and the surface topography were insufficient for MEMS applications. The potentiodynamic polarization results indicated that the...

Electrical properties of organic light-emitting diodes by indium tin oxide chemical-mechanical polishing process

In this study, the optimum process parameters and the influences of their process parameters were investigated for indium tin oxide chemical-mechanical polishing (ITO-CMP) with a sufficient removal amount and good planarity. Next, the organic light-emitting display (OLED) device with the structure of glass∕ITO∕poly[2-methoxy-5-(2-ethylhexyloxy)-p-phenylenevinylene]∕Al using a polished ITO surface as a bottom electrode (anode) was fabricated. The electrical characteristics, such as sheet resistance and current-voltage (I‐V) relationship, are discussed in order to evaluate the possibility of the CMP application for an OLED device using an ITO film. The surface morphology and I‐V characteristics of ITO thin film were improved after the CMP process using optimized process parameters compared to that of the as-deposited thin film before the CMP process.

Surface planarization of ZnO thin film for optoelectronic applications

In this paper, surface morphology and optical properties are investigated to find the optimum microstructure of zinc oxide (ZnO) thin films deposited by radio frequency (RF) magnetron sputtering. To achieve a high transmittance and a low resistivity, we examined various film deposition conditions. The transmittance and surface morphology of ZnO thin films were measured by an ultraviolet (UV)-visible spectrometer and atomic force microscopy (AFM), respectively. In order to improve the surface quality of ZnO thin films, we performed chemical mechanical polishing (CMP) by change of process parameters, and compared the optical properties of polished ZnO thin films. As an experimental result, we were able to obtain good uniformity and improved transmittance efficiency by the CMP technique.

CMP Properties of Oxide Film with Various Pad Conditioning Temperatures

Chemical mechanical polishing(CMP) performances can be optimized by several process parameters such as equipment and consumables (pad, backing film and slurry). Pad properties are important in determining removal rate and planarization ability of a CMP process. It is investigated the performance of oxide CMP process using commercial silica slurry after the pad conditioning temperature was varied. Conditioning process with the high temperature made the slurry be unrestricted to flow and be hold, which made the removal rate of oxide film increase. The pad became softer and flexible as the conditioning temperature increases. Then the softer pad provided the better surface planarity of oxide film without defect.

Improvement of Chemical Mechanical Polishing (CMP) Performance of Nickel by Additions of Abrasive and Various Oxidizers

Chemical mechanical polishing (CMP) of Ni was performed by the various ratios of four kinds of oxidizers and an addition of alumina powders as an abrasive in each slurry with the different oxidizers. Moreover, the interaction between the Ni and the each oxidizer was discussed by potentiodynamic polarization measurement, in order to compare the effects of Ni-CMP and electrochemical characteristics on the Ni with the different oxidizers. As an experimental result, the removal rate of Ni reached a maximum at 1 of . Also the removal rates of Ni increased with the audition of alumina abrasives in each slurry. The potentiodynamic polarization of Ni under dynamic condition showed a significant difference in electrochemical behavior by addition of in solutions. Ni showed the perfect passivation behavior in solution without under potentiodynamic polarization condition, while active dissolution dominates in solution with the addition of . The results indicate that the surface chemistry and electrochemical characteristics of Ni play an important role in controlling the polishing behavior of Ni.

A Study on CMP Properties of SnO 2 Thin Film for Application of Gas Sensor

SnO is one of the most suitable gas sensor materials. The microstructure and surface morphology of films must be controlled because the electrical and optical properties of SnO films depend on these characteristics. The effects of chemical mechanical polishing(CMP) on the variation of morphology of SnO films prepared by RF sputtering system were investigated. The commercially developed ceria-based oxide slurry, silica-based oxide slurry, and alumina-based tungsten slurry were used as CMP slurry. Non-uniformities of all slurries met stability standards of less than 5 %. Silica slurry had the highest removal rate among three different slurries, sufficient thin film topographies and suitable root mean square(RMS) values.