• Journal of the Korean Ceramic Society
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• v.40 no.8
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• pp.739-745
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• 2003

In $N_{x}$ films were deposited on soda-lime glass without substrate heating by reactive dc magnetron sputtering using indium (In) metal target. Depositions were carried out under various total gas pressures ( $P_{tot}$) of mixture gases (Ar+$N_2$ or He+$N_2$). He gas was introduced to $N_2$ gas in order to enhance the reactivity of nitrogen on film surface by the "penning ionization". Plasma impedance decreased greatly when 20% or more introduced the $N_2$ gas. This is due to the In $N_{x}$ layers formed on target surface because a secondary electron emission rate of InN is small compared with In metal. XRD patterns of the films revealed that <001> preferred oriented polycrystalline In $N_{x}$ films, where the crystallinity of the films was improved with decrease of $P_{tot}$ and with increase of $N_2$ flow ratio. The improvement of the crystallinity and stoichimetry of the In $N_{x}$ films were considered to be caused by an increase in the activated nitrogen radicals and also by an increase in the kinetic energy of sputtered In atoms arriving at growing film surface, which should enhance the chemical reaction and surface migration on the growing film surface, respectively. Furthermore, the films deposited using mixture gases of He+$N_2$ showed higher crystallinity compared with the film deposited by the mixture gases of Ar+$N_2$.$.EX>.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.389-389
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• 2012

Molybdenum is one of the most important materials used as a back ohmic contact for $Cu(In,Ga)(Se,S)_2$ (CIGS) solar cells because it has good electrical properties as an inert and mechanically durable substrate during the absorber film growth. Sputter deposition is the common deposition process for Mo thin films. Molybdenum thin films were deposited on soda lime glass (SLG) substrates using direct-current planar magnetron sputtering technique. The outdiffusion of Na from the SLG through the Mo film to the CIGS based solar cell, also plays an important role in enhancing the device electrical properties and its performance. The structure, surface morphology and electrical characteristics of Mo thin films are generally dependent on deposition parameters such as DC power, pressure, distance between target and substrate, and deposition temperature. The aim of the present study is to show the resistivity of Mo layers, their crystallinity and morphologies, which are influenced by the substrate temperature. The thickness of Mo films is measured by Tencor-P1 profiler. The crystal structures are analyzed using X-ray diffraction (XRD: X'Pert MPD PRO / Philips). The resistivity of Mo thin films was measured by Hall effect measurement system (HMS-3000/0.55T). The surface morphology and grain shape of the films were examined by field emission scanning electron microscopy (FESEM: Hitachi S-4300). The chemical composition of the films was obtained by the energy dispersive X-ray spectroscopy (EDX). Finally the optimum substrate temperature as well as deposition conditions for Mo thin films will be developed.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.96-97
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• 2012

In nitride and oxide film deposition, sputtered metals react with nitrogen or oxygen gas in a vacuum chamber to form metal nitride or oxide films on a substrate. The physical properties of sputtered films (metals, oxides, and nitrides) are strongly influenced by magnetron plasma density during the deposition process. Typical target power densities on the magnetron during the deposition process are ~ (5-30) W/cm2, which gives a relatively low plasma density. The main challenge in reactive sputtering is the ability to generate a stable, arc free discharge at high plasma densities. Arcs occur due to formation of an insulating layer on the target surface caused by the re-deposition effect. One current method of generating an arc free discharge is to use the commercially available Pinnacle Plus+ Pulsed DC plasma generator manufactured by Advanced Energy Inc. This plasma generator uses a positive voltage pulse between negative pulses to attract electrons and discharge the target surface, thus preventing arc formation. However, this method can only generate low density plasma and therefore cannot allow full control of film properties. Also, after long runs ~ (1-3) hours, depends on duty cycle the stability of the reactive process is reduced due to increased probability of arc formation. Between 1995 and 1999, a new way of magnetron sputtering called HIPIMS (highly ionized pulse impulse magnetron sputtering) was developed. The main idea of this approach is to apply short ${\sim}(50-100){\mu}s$ high power pulses with a target power densities during the pulse between ~ (1-3) kW/cm2. These high power pulses generate high-density magnetron plasma that can significantly improve and control film properties. From the beginning, HIPIMS method has been applied to reactive sputtering processes for deposition of conductive and nonconductive films. However, commercially available HIPIMS plasma generators have not been able to create a stable, arc-free discharge in most reactive magnetron sputtering processes. HIPIMS plasma generators have been successfully used in reactive sputtering of nitrides for hard coating applications and for Al2O3 films. But until now there has been no HIPIMS data presented on reactive sputtering in cluster tools for semiconductors and MEMs applications. In this presentation, a new method of generating an arc free discharge for reactive HIPIMS using the new Cyprium plasma generator from Zpulser LLC will be introduced. Data (or evidence) will be presented showing that arc formation in reactive HIPIMS can be controlled without applying a positive voltage pulse between high power pulses. Arc-free reactive HIPIMS processes for sputtering AlN, TiO2, TiN and Si3N4 on the Applied Materials ENDURA 200 mm cluster tool will be presented. A direct comparison of the properties of films sputtered with the Advanced Energy Pinnacle Plus + plasma generator and the Zpulser Cyprium plasma generator will be presented.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.151-151
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• 2012

A new plasma process, i.e., the combination of PIII&D and HIPIMS, was developed to implant non-gaseous ions into materials surface. HIPIMS is a special mode of operation of pulsed-DC magnetron sputtering, in which high pulsed DC power exceeding ~1 kW/$cm^2$ of its peak power density is applied to the magnetron sputtering target while the average power density remains manageable to the cooling capacity of the equipment by using a very small duty ratio of operation. Due to the high peak power density applied to the sputtering target, a large fraction of sputtered atoms is ionized. If the negative high voltage pulse applied to the sample stage in PIII&D system is synchronized with the pulsed plasma of sputtered target material by HIPIMS operation, the implantation of non-gaseous ions can be successfully accomplished. The new process has great advantage that thin film deposition and non-gaseous ion implantation along with in-situ film modification can be achieved in a single plasma chamber. Even broader application areas of PIII&D technology are believed to be envisaged by this newly developed process. In one application of non-gaseous plasma immersion ion implantation, Ge ions were implanted into SiO2 thin film at 60 keV to form Ge quantum dots embedded in SiO2 dielectric material. The crystalline Ge quantum dots were shown to be 5~10 nm in size and well dispersed in SiO2 matrix. In another application, Ag ions were implanted into SS-304 substrate to endow the anti-microbial property of the surface. Yet another bio-application was Mg ion implantation into Ti to improve its osteointegration property for bone implants. Catalyst is another promising application field of nongaseous plasma immersion ion implantation because ion implantation results in atomically dispersed catalytic agents with high surface to volume ratio. Pt ions were implanted into the surface of Al2O3 catalytic supporter and its H2 generation property was measured for DME reforming catalyst. In this talk, a newly developed, non-gaseous plasma immersion ion implantation technique and its applications would be shown and discussed.

• Journal of Surface Science and Engineering
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• v.46 no.6
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• pp.248-257
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• 2013

It is generally recognized that thin Pd-Cu alloy films fabricated by sputtering show a wide range of microstructures and properties, both of which are highly dependent on the sputtering conditions. In view of this, the present study aims to investigate the relationship between the performance of hydrogen separation membranes and the microstructure of Pd alloy films depending on sputtering deposition conditions such as substrate temperature, working pressure, and DC power. We fabricated thin and dense Pd-Cu alloy membranes by the micro-polishing of porous Ni support, an advanced Pd-Cu sputtered multi-deposition under the conditions of high substrate temperature / low working pressure / high DC power, and a followed by Cu-reflow heat-treatment. The result of a hydrogen permeation test indicated that the selectivity for $H_2/N_2$ was infinite because of the void-free and dense surface of the Pd alloy membranes, and the hydrogen permeability was 10.5 $ml{\cdot}cm^{-2}{\cdot}min^{-1}{\cdot}atm^{-1}$ for a 6 ${\mu}m$ membrane thickness.

• Korean Journal of Materials Research
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• v.26 no.4
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• pp.207-211
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• 2016

Ti films were deposited on glass substrates under various preparation conditions in a chamber of two-facing-target type dc sputtering; after deposition, the electric resistivity values were measured using a conventional four-probe method. Crystallographic orientations and microstructures, including the texture and columnar structure, were also investigated for the Ti films. The morphological features, including the columnar structures and surface roughness, are well explained on the basis of Thornton's zone model. The electric resistivity and the thermal coefficient of the resistivity vary with the sputtering gas pressure. The minimum value of resistivity was around 0.4 Pa for both the $0.5{\mu}m$ and $3.0{\mu}m$ thick films; the apparent tendencies are almost the same for the two films, with a small difference in resistivity because of the different film thicknesses. The films deposited at high gas pressures show higher resistivities. The maximum of TCR is also around 0.4 Pa, which is the same as that obtained from the relationship between the resistivity and the gas pressure. The lattice spacing also decreases with increasing sputtering gas pressure for both the $0.5{\mu}m$ and $3.0{\mu}m$ thick films. Because they are strongly related to the sputtering gas pressures for Ti films that have a crystallographic anisotropy that is different from cubic symmetry, these changes are well explained on the basis of the film microstructures. It is shown that resistivity measurement can serve as a promising monitor for microstructures in sputtered Ti films.

• Journal of the Korean Magnetics Society
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• v.25 no.2
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• pp.47-51
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• 2015

To achieve a high tunneling magneto resistance (TMR) of sputtered magnetic tunnel junctions (MTJs) with an MgO barrier, the annealing process is indispensable. The structural and compositional changes as consequences of the annealing greatly affect the spin-dependent transport properties of MTJs. Higher TMR could be obtained for MTJs annealed at higher annealing temperature. The diffusion of Ru, Mn and/or Ta in the MTJs may occur during annealing process, which is known to be detrimental to spin-dependent tunneling effect. The rapid thermal annealing (RTA) process was used for annealing the MTJs with synthetic antiferromagnets. To suppress the diffusion of Mn, Ru and/or Ta in the MTJs, the process time and temperature of RTA were minutely controlled.

• Journal of the Microelectronics and Packaging Society
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• v.13 no.4
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• pp.45-50
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• 2006

Copper via filling is the important factor in 3-D stacking interconnection of SiP (system in package). As the packaging density is getting higher, the size of via is getting smaller. When DC electroplating is applied, a defect-free hole cannot be obtained in a small size via hole. To prevent the defects in holes, pulse and pulse reverse current was applied in copper via filling. The holes, $20\and\;50{\mu}m$ in diameter and $100{\sim}190\;{\mu}m$ in height. The holes were prepared by DRIE method. Ta was sputtered for copper diffusion barrier followed by copper seed layer IMP sputtering. Via specimen were filled by DC, pulse and pulse-reverse current electroplating methods. The effects of additives and current types on copper deposits were investigated. Vertical and horizontal cross section of via were observed by SEM to find the defects in via. When pulse-reverse electroplating method was used, defect free via were successfully obtained.

• Journal of the Korean Magnetics Society
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• v.11 no.3
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• pp.129-133
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• 2001

In this paper, we studied structural and magnetic properties of Ba-ferrite thin film deposited on Si(100) substrate with TiO$_2$ underlayer. Ba-ferrite thin films with TiO$_2$ underlayer were deposited by reactive RF/DC magnetron sputtering system at room temperature. TiO$_2$ underlayer was reactive sputtered with $O_2$. After deposition, the thin films were annealed at vatious temperatures to get the crystallized sample. Underlayer was used to prevent interdiffusion from Ba-ferrite thin film to substrate. The growth of Ba-ferrite thin films was influenced by TiO$_2$ underlayer. Easy magnetization direction is in-plane. From these results the Ba-ferrite film with TiO$_2$ underlayer can be used as longitudinal recording media.

• Journal of the Korean Magnetics Society
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• v.11 no.3
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• pp.122-128
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• 2001

In this paper, we studied structural and magnetic properties of Ba-ferrite thin film deposited on Si(100) substrate with various underlayers. Ba-ferrite thin films with various underlayers were deposited by reactive RF/DC magnetron sputtering system at room temperature. various underlayers was reactive sputtered with O$_2$. After deposition, the thin films were annealed at 850 $^{\circ}C$ to get the crystallized sample. Underlayers were used to prevent interdiffusion from Ba-ferrite thin film to substrate. The growth of Ba-ferrite thin films was influenced by underlayers. Easy magnetization direction is in-plane. From these results the Ba-ferrite film with various underlayers can be used as longitudinal recording media.