• Journal of the Korean institute of surface engineering
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• v.47 no.4
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• pp.168-173
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• 2014

The paper presents the comparative results of TiAlN coatings deposited by DC and pulsed DC asymmetric bipolar magnetron sputtering systems. The results show that, with the decreasing duty cycle and increasing pulse frequency, the coating morphology changes from a columnar to a dense structure, with finer grains. Pulsed sputtered TiAlN coatings showed higher hardness, higher residual stress, and smaller grain sizes than dc prepared TiAlN coatings. Moreover residual stress of pulsed sputtered TiAlN coatings increased on increasing pulse frequency. Meanwhile, the surface roughness decreased continuously with increasing pulsed DC frequency up to 50 kHz.

• Journal of the Korean institute of surface engineering
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• v.25 no.5
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• pp.223-233
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• 1992

(Ti, Al)N films were deposited on 304 stainless steel by D.C. magnetron sputtering using Al target and Ti plate. The properties of (Ti, Al)N films such as composition, microhardness, grain size, crystal structure were investigated. The chemical composition of (Ti, Al)N films was similar to the sputter area ratio of titanium to aluminum target by means of EDS and AES survey. The higher bias voltage to substrate and the smaller input of N2 gas showedthe increased microhardness and the finer grain size of the films. The results obtained from this study show, it is belived, that the (Ti, Al)N film by D.C.magne-tron sputtering is promising in the wear resistance use.

• Korean Journal of Materials Research
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• v.5 no.2
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• pp.169-177
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• 1995

The diffusion barrier property of 100-nm-thick titanium nitride (TiN) film between Cu and Si was investigated using sheet resistance measurements, etch-pit observation, x-ray diffractometry, Auger electron spectroscopy, and transmission electron microscopy. The TiN barrier fails due to the formation of crystalline defects (dislocations) and precipitates (presumably Cu-silicides) in the Si substrate which result from the predominant in-diffusion of Cu through the TiN layer. In contrast with the case of Al, it is identified that the TiN barrier fails only the in-diffusion of Cu because there is no indication of Si pits in the Si substrate. In addition, it appears that the stuffing of TiN does not improve the diffusion barrier property in the Cu/TiN/Si structure. This indicates that in the case of Al, the chemical effect that impedes the diffusion of Al by the reaction of Al with $TiO_{2}$ which is present in the grain boundaries of TIN is very improtant. On the while, in the case of Cu, there is no chemical effect because Cu oxides, such as $Cu_{2}O$ or CuO, is thermodynamically unstable in comparison with $TiO_{2}$. For this reason, it is considered that the effect of stuffing of TiN on the diffusion barrier property is not significant in the Cu/ TiN/Si structure.

• Journal of Powder Materials
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• v.20 no.4
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• pp.285-290
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• 2013

$Ti_2AlN$ composites are a laminated compounds that posses unique combination of typical ceramic properties and typical metallic(Ti alloy) properties. In this paper, the powder synthesis, SPS sintering, composite characteristics and machinability evaluation were systematically conducted. The random orientation characteristics and good crystallization of the $Ti_2AlN$ phase are observed. The electrical and thermal conductivity of $Ti_2AlN$ is higher than that of Ti6242 alloy. A machining test was carried out to compare the effect of material properties on micro electrical discharge drilling for $Ti_2AlN$ composite and Ti6242 alloy. Also, mixture table as a kind of tables of orthogonal arrays was used to know how parameter is main effective at experimental design. Consequently, hybrid $Ti_2AlN$ ceramic composites showed good machining time and electrode wear shape under micro ED-drilling process. This conclusion proves the feasibility in the industrial applications.

• Korean Journal of Materials Research
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• v.5 no.1
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• pp.87-95
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• 1995

The effect of stuffing of TiN on the diffusion barrier property between A1 and Si was investigated. The stuffing of TiN was performed by annealing in a Nz ambient at $450^{\circ}C$ for 30min. By TEM analysis, it is identified that there are solid-free or open spaces of a b u t 10-20$\AA$ between the grains of asdeposited TiN. In the case of stuffed TiN, the width of solid-free or open spaces has been reduced to about 10$\AA$ or below. The combination of RBS and AES analyses showed that the asdeposited TiN had about 7at.% of oxygen, and that the stuffed TiN had about 10-15at.% of oxygen. The diffusion barrier test result shows that after annealing at $650^{\circ}C$ for lhour, the asdeposited TiN fails due to the formation of A1 spikes and Si pits in the Si substrate. However, in the case of stuffed TiN, there is no indication of Al spikes and Si pits at the same annealing condition. Thus, it is concluded that this stuffing of TiN significantly improves the diffusion barrier property of TiN between A1 and Si. It is considered that the stuffing effect results from the reduced diffusion through grain boundaries due to the reduced spacing of grain boundaries.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.266-267
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• 2011

질화갈륨(GaN)은 높은 전자이동도 및 높은 항복전계를 가지며 낮은 온저항으로 인하여 에너지효율이 우수하기 때문에 고출력 전력소자 분야에서 많은 관심을 받고 있다. GaN을 이용한 고출력 전력소자의 경우 상용화 수준에 근접할 만한 기술적 진보가 있었으나, 페르미 레벨 고정(Fermi-level pinning) 현상, 소자의 누설전류 등 아직 해결되어야 할 문제를 갖고 있다. 본 연구에서는 실리콘 기판 위에 성장된 GaN 에피탁시를 활용한 고출력 전력소자의 누설전류를 억제시키기 위해 오믹 접합 중 Au의 상호확산을 억제하는 중간층 금속(Mo or Ni)을 변화시켰으며 오믹 열처리 온도에 따른 특성을 비교 연구하였다. $Cl_2$와 $BCl_3$를 이용하여 0.6 ${\mu}m$ 깊이의 메사 구조가 활성영역을 형성하였고, Si 도핑된 n-GaN 위에 Ti/Al/Mo/Au (20/100/25/200 nm) 와 Ti/Al/Ni/Au (20/100/25/200 nm) 오믹 접합을 각각 설계, 제작하였다. 오믹 열처리시의 GaN 표면오염을 방지하기 위해 $SiO_2$ 희생층을 증착하였다. 오믹 접합 형성을 위해 각 750$^{\circ}C$, 800$^{\circ}C$, 850$^{\circ}C$에서 30초간 열처리를 진행 하였으며, 이후 6 : 1 BOE 용액으로 $SiO_2$ 희생층을 제거하였다. 750, 800, 850$^{\circ}C$에서 Ti/Al/Mo/Au 구조의 오믹 접합 저항은 각 2.56, 2.34, 2.22 ${\Omega}$-mm 이었으며, Ti/Al/Ni/Au 구조의 오믹 접합 저항은 각 43.72, 2.64, 1.86 ${\Omega}$-mm이었다. Isolation 누설전류를 측정하기 위해서 두 개의 오믹 접합 사이에 메사 구조가 있는 테스트 구조를 제안하였다. Isolation 누설전류는 Ti/Al/Mo/Au 구조에서 두 오믹 접합 사이의 거리가 25 ${\mu}m$이고 100 V일 때 750, 800, 850 $^{\circ}C$의 열처리 온도에서 각 1.25 nA/${\mu}m$, 2.48 nA/${\mu}m$, 8.76 nA/${\mu}m$이었으며, Ti/Al/Ni/Au 구조에서는 각 1.58 nA/${\mu}m$, 2.13 nA/${\mu}m$, 96.36 nA/${\mu}m$이었다. 열처리 온도가 증가하며 오믹 접합 저항은 감소하였으나 isolation 누설전류는 증가하였다. 750$^{\circ}C$ 열처리에서 오믹 접합 저항은Ti/Al/Mo/Au 구조가 Ti/Al/Ni/Au 구조보다 약 17배 우수하였고, 850$^{\circ}C$ 고온의 열처리 경우 Ti/Al/Mo/Au 구조의 isolation 누설전류는 8.76 nA/${\mu}m$로 Ti/Al/Ni/Au의 누설전류 96.36 nA/${\mu}m$보다 약 11배 우수하였다. Ti/Al/Mo/Au가 Ti/Al/Ni/Au 보다 오믹 접합 저항과 isolation 누설전류 측면에서 전력용 GaN 소자에 적합함을 확인하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.107-107
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• 2016

TiCrAlSiN films were developed in order to improve the high-temperature oxidation resistance, corrosion resistance, and mechanical properties of conventional TiN films that are widely used as hard films to protect and increase the lifetime and performance of cutting tools or die molds. In this study, a nano-multilayered TiAlCrSiN film was deposited by cathodic arc plasma deposition. It displayed relatively good oxidation resistance at $700-900^{\circ}C$, owing to the formation protective oxides of $Al_2O_3$, $Cr_2O_3$, and $SiO_2$, and semiprotective $TiO_2$. At $1000^{\circ}C$, the increased temperature led to the formation of the imperfect oxide scale that consisted primarily of the outer ($TiO_2$,$Al_2O_3$)-mixed scale and inner ($TiO_2$, $Al_2O_3$, $Cr_2O_3$)-mixed scale.

• Korean Journal of Materials Research
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• v.12 no.9
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• pp.718-723
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• 2002

$Ti_{1-x}$ $Al_{ x}$N thin films as barrier layer for memory devices application were deposited by reactive magnetron sputtering. The crystallinity, micro-structure, oxidation resistance and oxidation mechanism of films were investigated as a function of Al content. Lattice parameter and grain size of thin films were decreased with increasing the Al content Oxidation of the film with higher Al content is slow and then, total oxide thickness is thinner than that of lower Al content film. Oxide layer formed on the surface is AlTiNO layer. Oxidation of $Ti_{1-x}$ /$Al_{x}$ N barrier layer is diffusion limited process and thickness of oxide layer with oxidation time increased with a parabolic law. The activation energy of oxygen diffusion, Ea and diffusion coefficient, D of $Ti_{0.74}$ /X$0.74_{0.26}$N film is 2.1eV and $10^{-16}$ ~$10^{-15}$ $\textrm{cm}^2$/s, respectively. $_Ti{1-x}$ /$Al_{x}$ XN barrier layer showed good oxidation resistance.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.97.2-97.2
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• 2018

This study formed a hard TiAlSiWN coating layer using Ti, Al, Si and W raw powders that were mechanically alloyed and refined. The TiAlSi and TiAlSiW coating targets were fabricated using a single PCAS process in a short time with the optimal sintering conditions. The coating targets were deposited on the WC substrate by forming coating layers using TiAlSiN and TiAlSiWN nitride nano-composite structures with an AIP process. The properties of the nitride nano-composite coating layers were compared according to the addition of W. The microstructure of the nitride nano-composite coating layer was analyzed, focusing on the distribution of the crystalline phases, amorphous phases ($Si_3N_4$), and growth orientation of the columnar crystal depending on the addition of W. The mechanical properties of the coating layers were exhibited a hardness of approximately $3,000kg/mm^2$ and adhesion of about 117.77N in the TiAlSiN. In particular, the TiAlSiWN showed excellent properties with a hardness of more than $4,300kg/mm^2$ and an adhesion of about 181.47N.

• Journal of the Korean Society for Heat Treatment
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• v.16 no.6
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• pp.329-334
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• 2003

Microstructure and mechanical properties of $(Ti_{1-x}Alx)N$ films, Produced by the the Ion Beam Sputtering(IBS) method, were studied by changing the Ti, Al contents. The compositions of films determined by RBS were $(Ti_{0.75}Al_{0.25})N$, $(Ti_{0.61}Al_{0.39})N$ and $(Ti_{0.5}Al_{0.5})N$, and XPS binding energies of Ti2P, A12p and N1s shifted to higher energies than those of pure Ti, Al and N, which indicated that nitrides were formed. XRD results indicated that the NaCl structure for $$x{\leq_-}0.39$$ changed into amorphous structure at x=0.5. For films with $$x{\leq_-}0.39$$, the lattice parameter decreased in proportion to the Al content. Nanoindentation hardness value were above HV=3300 at Al content up to x=0.39. However, the hardness of films with x=0.5 abruptly decreased to HV=1800, and this lower hardness values were attributed to different crystal structure. Critical load(Lc) in scratch test showed 23N at x=0.25, 22N at x=0.39 and 22N at x=0.5, which indicated that films with different Al contents showed similar adhesion behavior.