• Korean Journal of Materials Research
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• v.28 no.4
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• pp.241-246
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• 2018

$TaN_x$ film is grown by plasma enhanced atomic layer deposition (PEALD) using t-butylimido tris(dimethylamido) tantalum as a metalorganic source with various reactive gas species, such as $N_2+H_2$ mixed gas, $NH_3$, and $H_2$. Although the pulse sequence and duration are the same, aspects of the film growth rate, microstructure, crystallinity, and electrical resistivity are quite different according to the reactive gas. Crystallized and relatively conductive film with a higher growth rate is acquired using $NH_3$ as a reactive gas while amorphous and resistive film with a lower growth rate is achieved using $N_2+H_2$ mixed gas. To examine the relationship between the chemical properties and resistivity of the film, X-ray photoelectron spectroscopy (XPS) is conducted on the ALD-grown $TaN_x$ film with $N_2+H_2$ mixed gas, $NH_3$, and $H_2$. For a comparison, reactive sputter-grown $TaN_x$ film with $N_2$ is also studied. The results reveal that ALD-grown $TaN_x$ films with $NH_3$ and $H_2$ include a metallic Ta-N bond, which results in the film's higher conductivity. Meanwhile, ALD-grown $TaN_x$ film with a $N_2+H_2$ mixed gas or sputtergrown $TaN_x$ film with $N_2$ gas mainly contains a semiconducting $Ta_3N_5$ bond. Such a different portion of Ta-N and $Ta_3N_5$ bond determins the resistivity of the film. Reaction mechanisms are considered by means of the chemistry of the Ta precursor and reactive gas species.

• Applied Microscopy
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• v.50
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• pp.7.1-7.10
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• 2020

Tantalum nitride (TaN_x) thin films were grown utilizing an inductively coupled plasma (ICP) assisted direct current (DC) sputtering, and 20-100% improved microhardness values were obtained. The detailed microstructural changes of the TaN_x films were characterized utilizing transmission electron microscopy (TEM), as a function of nitrogen gas fraction and ICP power. As nitrogen gas fraction increases from 0.05 to 0.15, the TaN_x phase evolves from body-centered-cubic (b.c.c.) TaN_0.1, to face-centered-cubic (f.c.c.) δ-TaN, to hexagonal-close-packing (h.c.p.) ε-TaN phase. By increasing ICP power from 100 W to 400 W, the f.c.c. δ- TaN phase becomes the main phase in all nitrogen fractions investigated. The higher ICP power enhances the mobility of Ta and N ions, which stabilizes the δ-TaN phase like a high-temperature regime and removes the micro-voids between the columnar grains in the TaN_x film. The dense δ-TaN structure with reduced columnar grains and micro-voids increases the strength of the TaN_x film.

• Progress in Superconductivity and Cryogenics
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• v.23 no.2
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• pp.1-5
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• 2021

We have investigated the electrical transport properties of polycrystalline tantalum nitride (TaN_x) films. Various compositions of tantalum (nitride) thin films have been deposited on SiO₂ substrates by reactive DC magnetron sputtering while changing the ratio of nitrogen partial pressure. The substrate temperature was maintained at 283 K during deposition. X-ray diffraction analyses indicated the presence of α-Ta and β-Ta phases in the Ta film deposited in pure argon atmosphere, while fcc-TaN_x phases appeared in the sputtering gas mixture of argon and nitrogen. The N/Ta atomic ratio in the film increased ranging from 0.36 to 1.07 for nitrogen partial pressure from 7 to 20.7%. The superconducting transition temperatures of the TaN_x thin films were measured to be greater than 3.86 K with a maximum of 5.34 K. The electrical resistivity of TaN_x thin film was in the range of 177-577 𝜇Ωcm and increased with an increase in nitrogen content. The upper critical filed at zero temperature for a TaN_0.87 thin film was estimated to exceed 11.3 T, while it showed the lowest T_c = 3.86 K among the measured superconducting TaN_x thin films. We try to explain the behavior of the increase of the residual resistivity and the upper critical field for TaN_x thin films with the nitrogen content by using the combined role of the intergrain Coulomb effect and disorder effect by grain boundaries.

• Journal of the Microelectronics and Packaging Society
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• v.16 no.3
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• pp.19-24
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• 2009

Formation of an adhesion/barrier layer and a seed layer by sputtering techniques followed by electroplating has been one of the most widely used methods for the filling of through-Si via (TSV) with high aspect ratio for 3-D packaging. In this research, the adhesion and diffusion-barrier properties of the $TaN_x$ film deposited by reactive sputtering were investigated. The adhesion strength between Cu film and $SiO_2$/Si substrate was quantitatively measured by $180^{\circ}$ peel test and topple test as a function of the composition of the adhesive $TaN_x$ film. As the nitrogen content increased in the adhesive $TaN_x$ film, the adhesion strength between Cu and $SiO_2$/Si substrate increased, which was attributed to the increased formation of interfacial compound layer with the nitrogen flow rate. We also examined the diffusion-barrier properties of the $TaN_x$ films against Cu diffusion and found that it was improved with increasing nitrogen content in the $TaN_x$ film up to N/Ta ratio of 1.4.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.24.1-24.1
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• 2009

Tantalum carbo-nitride($T_aC_xN_y$) films were deposited with chemical vapor deposition(CVD) using tert-butylimido tris-diethylamido tantalum (TBTDET, $^tBu-N=Ta-(NEt_2)_3$, $Et=C_2H_5$, $^tBu=C(CH_3)_3$) between $350^{\circ}C$ and $600^{\circ}C$ with argon as a carrier gas. Fourier transform infrared (FT-IR)spectroscopy was used to study the thermal decomposition behavior of TBTDET in the gas phase. When the temperature was increased, C-H and C-N bonding of TBTDET disappeared and the peaks of ethylene appeared above $450^{\circ}C$ in the gas phase. The growth rate and film density of $T_aC_xN_y$ film were in the range of 0.1nm/min to 1.30nm/min and of $8.92g/cm^3$ to $10.6g/cm^3$ depending on the deposition temperature. $T_aC_xN_y$ films deposited below $400^{\circ}C$ were amorphous and became polycrystal line above $500^{\circ}C$. It was confirmed that the $T_aC_xN_y$ film was a mixture of TaC, graphite, $Ta_3N_5$, TaN, and $Ta_2O_5$ phases and the oxide phase was formed from the post deposition oxygen uptake. With the increase of the deposition temperature, the TaN phase was increased over TaC and $Ta_3N_5$ and crystallinity, work function, conductivity and density of the film were increased. Also the oxygen uptake was decreased due to the increase of the film density. With the increase of the TaC phase in $T_aC_xN_y$ film, the work function was decreased to 4.25eV and with the increase of the TaN phase in $T_aC_xN_y$ film,it was increased to 4.48eV.

• Journal of the Korean Vacuum Society
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• v.3 no.2
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• pp.190-197
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• 1994

본 연구에서는 DC magnetron 스퍼터링법을 이용하여 고정밀, 고저항 저항체 박막으로 TaNx film을 제조하였을 때 형성될 수 있는 화합물 중 TaN0.1, TaN0.8과 TaN 박막의 Rs와 TCR특성을 평가하 고 film층의 우선방향성을 XRD를 이용하여 판명한 뒤 저항체의 Rs와 TCR에 미치는 영향을 조사하였 다. TaN0.1 박막이 35$\Omega$/$\square$의 면저항값과 안정된 TCR값을 나타내는 것을 알수 있었다. 두께50~200nm 의 TaN0.1과 Alumina 기판 사이에 정(+)의 TCR을 갖는 약 50nm의 Cr층을 증착하였을 때 Rs는 180$\Omega$/ $\square$ 과 TCR는 20ppm/$^{\circ}C$인 적층박막을 제조할 수 있었다. TaN0.1, TaN0.8 과 TaN 시편에서 화합물 형성 에 따른 Ta의 결합에너지를 ESCA를 이용하여 조사하였다. 이상의 연구결과로부터 TaN0.1 film이 TaNfilm 보다 고정밀, 고저항 박막 저항체 제조에 있어 우수한 전기저항 특성을 가지며 Cr 중간층 형성 으로 TCR이 $\pm$ppm/$^{\circ}C$정도로 안정된 고정밀 다층 저항체 박막을 형성할 수 있었다.

• Korean Journal of Materials Research
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• v.27 no.1
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• pp.32-38
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• 2017

Insulating $TaN_x$ films were grown by plasma enhanced atomic layer deposition using butylimido tris dimethylamido tantalum and $N_2+H_2$ mixed gas as metalorganic source and reactance gas, respectively. Crossbar devices having a $Pt/TaN_x/Pt$ stack were fabricated and their electrical properties were examined. The crossbar devices exhibited temperature-dependent nonlinear I (current) - V (voltage) characteristics in the temperature range of 90-300 K. Various electrical conduction mechanisms were adopted to understand the governing electrical conduction mechanism in the device. Among them, the PooleFrenkel emission model, which uses a bulk-limited conduction mechanism, may successfully fit with the I - V characteristics of the devices with 5- and 18-nm-thick $TaN_x$ films. Values of ~0.4 eV of trap energy and ~20 of dielectric constant were extracted from the fitting. These results can be well explained by the amorphous micro-structure and point defects, such as oxygen substitution ($O_N$) and interstitial nitrogen ($N_i$) in the $TaN_x$ films, which were revealed by transmission electron microscopy and UV-Visible spectroscopy. The nonlinear conduction characteristics of $TaN_x$ film can make this film useful as a selector device for a crossbar array of a resistive switching random access memory or a synaptic device.

• Journal of the Korean institute of surface engineering
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• v.38 no.2
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• pp.65-68
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• 2005

The effect of crystal orientation and microstructure on the mechanical properties of $TaN_x$ was investigated. $TaN_x$ films were grown on $SiO_2$ substrates by ultrahigh vacuum unbalanced magnetron sputter deposition in mixed $Ar/N_2$ discharges at 20 mTorr (2.67 Pa) and at $350^{\circ}C$. Unlike the Ti-N system, in which TiN is the terminal phase, a large number of N-rich phases in the Ta-N system could lead to layers which had nano-sized lamella structure of coherent cubic and hexagonal phases, with a correct choice of nitrogen fraction in the sputtering mixture and ion irradiation energy during growth. The preferred orientations and the micro-structure of $TaN_x$ layers were controlled by varing incident ion energy $E_i\;(=30eV\~50eV)$ and nitrogen fractions $f_{N2}\;(=0.1\~0.15)$. $TaN_x$ layers were grown on (0002)-Ti underlayer as a crystallographic template in order to relieve the stress on the films. The structure of the $TaN_x$ film transformed from Bl-NaCl $\delta-TaN_x$ to lamellar structured Bl-NaCl $\delta-TaN_x$ + hexagonal $\varepsilon-TaN_x$ or Bl-NaCl $\delta-TaN_x$ + hexagonal $\gamma-TaN_x$ with increasing the ion energy at the same nitrogen fraction $f_{N2}$. The hardness of the films also increased by the structural change. At the nitrogen fraction of $0.1\~0.125$, the structure of the $TaN_x$ films was changed from $\delta-TaN_x\;+\;\varepsilon-TaN_x\;to\;\delta-TaN_x\;+\;\gamma-TaN_x$ with increasing the ion energy. However, at the nitrogen fraction of 0.15 the film structure did not change from $\delta-TaN_x\;+\;\varepsilon-TaN_x$ over the whole range of the applied ion energy. The hardness increased significantly from 21.1 GPa to 45.5 GPa with increasing the ion energy.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.537-540
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• 2001

This paper presents the characteristics of Ta-N thin-film for high precision resistors, which were deposited on Si substrate by DC reactive magnetron sputtering in an argon-nitrogen atmosphere(Ar-(4~16 %)$N_2$). Structural properties studied using X-ray diffraction(XRD) indicate the presence of TaN, $Ta_3N_5$ or a mixture of Ta-N phases in the films depending on the amount of nitrogen in the sputtering gas. The chemical composition are investigated by auger electro spectroscopy(AES). The optimized conditions of Ta-N thin-film resistors were deposited in 4 % $N_2$ gas flow ratio. Under optimum conditions, the Ta-N thin-film resistors are obtained a high resistivity, $\rho=305.7{\mu}{\Omega}cm$, a low temperature coefficient of resistance, TCR=-36 $ppm/^{\circ}C$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.537-540
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• 2001

This paper presents the characteristics of Ta-N thin-(ibm for high precision resistors, which were deposited oni substrate by DC reactive magnetorn sputtering in an argon-nitrogen atmosphere(Ar-(4∼16%)N$_2$). Sturcutural properties sutided using X-ray diffraction (XRD) indicate the presence of TaN, Ta$_3$N$\sub$5/ or a mixture of Ta-N phases in the films depending on the amount of nitrogen in the sputtering gas. The chemical composition are investigated by auger electro spectroscopy(AES). The optimized conditions of Ta-N thin-film resistors were deposited in 4 % N$_2$ gas flow ratio. Under optimum conditions, the Ta-N thin-film resistors are obtained a high resistivity, $\rho$=305.7 ${\mu}$Ωcm, a low temperature coefficient of resistance, TCR=-36 ppm/$^{\circ}C$.