Kyung H. Nam

Deposition of Ti thin film using the magnetron sputtering method

This paper presents a modification to conventional magnetron sputtering systems. The introduction of a grid in front of the target increases the metal ion ratio. Using OES and observing both Ti neutrals and ions, it was confirmed that the relative ionization could be qualitatively extended with grid-attached magnetron sputtering compared with a conventional magnetron system. On the other hand, the relative ionization of Ar decreased. Our results also show that the Ti films deposited by conventional magnetron exhibit (100) preferred orientation as the bias voltage increased. On the other hand, in the case of the grid-attached magnetron, the Ti films exhibit highly preferred (002) orientation with increasing bias voltage. The experiments clearly demonstrated that a dense Ti film with a smooth, specular reflecting surface can be produced using the grid-attached magnetron with increased Ti ion flux compared to the conventional magnetron.

A study on formation of Al and Al2O3 on the porous paper by DC magnetron sputtering

Abstract Understanding the mode of transport of water vapor through the film is important for improving the moisture barrier properties of metallized porous papers. For the synthesis of Al metallized porous papers, it was carried out by DC planar magnetron sputtering with various target power densities and film thickness. To correlate film characteristics with moisture barrier properties, film properties were determined by X-ray diffraction, scanning electron microscopy, Auger electron spectroscopy and evaluations of water vapor permeability (WVP). It changed preferred orientations from Al(1xa01xa01) to α-Al 2 O 3 (1xa01xa00) reacted with thermal activated oxygen from the paper as film thickness increase and the minimum WVP mean is 2.16×10 −7 gxa0mm/m 2 xa0hxa0kPa at 6.3 W/cm 2 , 2 μm and the maximum is 2.00×10 −8 gxa0mm/m 2 xa0hxa0kPa at 1.2 W/cm 2 , 0.2 μm.

Microstructure and optical properties of MgO films synthesized by closed-field unbalanced magnetron sputtering with additional electron emission

Abstract This paper investigated the discharge behaviour, microstructure and optical properties of magnesium oxide (MgO) films synthesized by closed-field unbalanced magnetron sputtering (CFUBM) with additional electron emission. For the evaluation of the effects on closed-field magnetic configuration and additional electron emission, MgO films were deposited by three types of magnetron sputtering with a circular Mg target and various O2 partial pressure: (i) the single unbalanced magnetron sputtering (UBM), (ii) CFUBM by a symmetrical arrangement of four magnetrons and (iii) CFUBM with additional electron emission by W-filament. As magnetic closed-field and additional electron emission were employed to magnetron discharges, poisoning ratio was reduced and deposition rate was increased approximately 1.5 times in comparison with that obtained in the single UBM. The saturated ion current density and the substrate temperature were increased with the attachment of magnetic closed-field and additional electron emission in MgO discharges, which means that these played an important role to enhance plasma density and ionization rate. As a results of microstructure and optical property analyses, an employment of magnetic closed-field and additional electron emission led to the high density MgO films with higher refractive index and transmittance, although MgO film coated by CFUBM showed the lowest refractive index due to the large number of planar defects.

Nucleation and growth behavior of chromium nitride film deposited on various substrates by magnetron sputtering

Abstract For the evaluation of nucleation and growth behaviors influenced by substrate properties, such structure and electrical properties, chromium nitride (CrN) films were deposited on various substrates (glass, AISI 1040 steel and Si(1xa01xa00)) by unbalanced magnetron sputtering. X-ray diffraction and atomic force microscopy were used to study the microstructure and grain growth as a function of deposition time. The diffraction patterns of CrN thin films deposited on Si(1xa01xa00) exhibited crystalline structure with highly preferred orientation of (2xa00xa00) plane parallel to the substrate, whereas the films deposited on glass and AISI 1040 exhibited preferred orientations (2xa00xa00) and minor orientation (1xa01xa01), (3xa01xa01) or (2xa02xa00) plane. The orientation of films deposited both on glass and Si substrates did not depend on the bias voltage ( V s ). At the same time, the crystallites of films deposited on AISI 1040 steel with the bias voltage of V s =−100 V had the orientation of (2xa02xa00) plane parallel to the substrate. The grain growth and structure of film deposited on AISI 1040 steel substrate are strongly influenced by the substrate bias in comparison with that deposited onto glass and Si substrates. The differences in the structure and grain growth of CrN films deposited onto different substrates are predominantly related to the properties of the substrate (structure and electrical conductivity).

High rate deposition of poly-Si thin films at low temperature using a new designed magnetron sputtering source

Abstract We have deposited poly-Si thin films on Si(100) and glass substrates at growth temperature of below 400°C using a newly developed high rate magnetron sputtering method. To improve the sputtering yield and the growth rate, a high power (10–30 W/cm 2 ) magnetron sputtering system was designed and constructed. Based on the results of computer simulation, we built up the magnetron sputter source with unbalanced magnetron and Si ion extraction grid. The maximum deposition rate reached was 0.35 μm/min due to a high ion bombardment. This is five times higher than that of conventional sputtering methods, and the sputtering yield was also increased up to 80%. The best film was obtained on Si(100) surface using Si ion extraction grid under 9.0×10 −3 torr of working pressure and 11 W/cm 2 of the target power density. The electron mobility of the poly-Si film grown on Si(100) at 400°C with ion extraction grid was 96 cm 2 /Vs. In this study, however, we found that the target power density is a more important factor than working pressure to influence the growth rate, mobility, and the film quality. During sputtering, moreover, the characteristics of Si sputter source were also analyzed with an in situ Langmuir probe method and optical emission spectroscopy.

Magnetron with gas injection through hollow cathodes machined in sputtered target

Abstract This article reports on a magnetron equipped with a target with holes. The holes machined in sputtered target can sustain hollow cathode discharges and/or inject the sputtering gas directly inside the magnetron discharge. This magnetron operates on the same principle as a gas-jet. It is shown that the size and number of holes can efficiently control I – V characteristics of the magnetron. The holes of large (≥2 mm) diameter can sustain hollow cathode discharges, which intensify the magnetron discharge. On the contrary, the holes of small (≤1 mm) diameter influences the I – V characteristics much less and allow: (i) to introduce the sputtering gas directly inside the discharge; and (ii) to compensate a gas density reduction in front of target when the magnetron is operated at high (≥100 W/cm 2 ) target power densities. Special attention is devoted to reactive sputtering. There is great difference in the deposition rate a D of films in the case when the sputtering gas is fed to the chamber or to the discharge through the holes. It is shown that for the gas feed to chamber, a D of the nitride films, sputtered from target with four holes of diameter 2 mm, is equal to that of pure metal films sputtered from a full target in argon. On the contrary, for the gas feed to discharge, a D of the oxide films, sputtered from target with four holes of diameter 2 mm, is very low, 40 times smaller compared to a D of metal films sputtered from a full target in argon. The magnetron discharge with an extremely low deposition rate is very suitable for cleaning and activation of surfaces prior to the film deposition.

Synthesis and properties of high density MgO films deposited by magnetron sputtering with ion extraction system

New magnetron sputtering system, which included simply designed ion extraction grids, was developed in our laboratory in order to synthesize high density MgO films. For the investigation of the effect on grids assisted magnetron, MgO films were synthesized by three types of magnetron: (i) conventional magnetron; (ii) one grid assisted magnetron; and (iii) two grids assisted magnetron. The saturated substrate ion current density and Mg ion fraction in MgO discharges generated by grids assisted magnetron were increased in comparison with those obtained in conventional magnetron, which means that the grids assisted magnetron led to the enhancement of plasma density. An employment of ion extraction grids in magnetron sputtering induced the increase of film density as well as transmittance and the decrease of Rms roughness.