Tantalum Nitride Thin Films Research Articles

Stress, Microstructure and Temperature Stability of Reactive Sputter Deposited Ta(N) Thin Films

AbstractInterest in tantalum nitride thin films for use as diffusion barriers in Cu-based microelectronic interconnects merits the study of tantalum nitride thin film properties as a function of deposition conditions and elevated temperature exposure. In this investigation, the influence of nitrogen content and post deposition annealing on the stress, microstructure and resistivity of Ta(N) films was analyzed. Ta(N) thin films were deposited by reactive dc magnetron sputtering of a Ta target in Ar/N2 gas mixtures. With an increasing N2 to Ar flow ratio, the as-deposited crystal structure of the films changed from ß-Ta to bcc Ta with N in solid solution to TaN0.1 to Ta2N and finally to TaN. The as-deposited Ta(N) stress, grain size and resistivity of the films were found to be strongly dependent on the phase(s) present. Films with less than 20 at. % nitrogen concentration displayed large compressive stress increases during 650°C anneals in flowing N2. Phase transformations to Ta2N occurred after 650°C anneals in films with nitrogen concentrations from ∼ 15 to 25 at. %. Microstructural characterization using transmission electron microscopy and x-ray diffraction, and chemical analysis by x-ray photoelectron spectroscopy and Auger electron spectroscopy of the Ta(N) films were used to identify the as-deposited and transformed phases.

A Study on the Grain Boundary Diffusion of Copper in Tantalum Nitride Thin Films

This work measures the diffusivity of copper tantalum nitride thin films. Auger electron spectroscopy is performed to measure the concentration profile of . In addition, the morphology and crystalline microstructure of the tantalum hitride films were investigated by atomic force microscopy, cross‐sectional transmission electron microscopy, and X‐ray diffraction. After annealing the samples at fixed temperatures between 500 and , both the lattice and grain boundary diffusivities were extracted from the concentration profile on the basis of the Whipple analysis of grain boundary diffusion. The and values obtained followed an Arrhenius dependence from 500 to and . ©1999 The Electrochemical Society

Reactive sputter deposition and characterization of tantalum nitride thin films

Electrical and structural properties of tantalum nitride films, deposited on GaAs substrates by a d.c. magnetron sputtering technique at different nitrogen partial pressures for use as resistors in integrated circuits, have been reported. Sheet resistivity measurements indicate that stoichiometric TaN films with stable resistivity values can be obtained if the nitrogen partial pressure is maintained between 10.5 and 20.6%. Structural properties studied using X-ray diffraction indicate the presence of pure Ta, 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 temperature coefficient of resistivity measured for the films deposited with the nitrogen partial pressure around 13% showed a stable value of −200 ppm K −1. Fabricated TaN thin-film resistors showed resistance values within ±10% of the designed value, suggesting the possibility of integrating these resistors with devices.

Remote Plasma-Assisted Metal Organic Chemical Vapor Deposition of Tantalum Nitride Thin Films with Different Radicals

Thin films of tantalum nitride have been deposited from remote plasma-assisted metal organic chemical vapor deposition (RP-MOCVD) using the reaction of pentakis-dimethyl-amino-tantalum (PDMATa) with different activated radicals. Microstructures of deposited films measured by X-ray diffraction (XRD) and transmission electron microscopy (TEM) depend on the deposition temperature and the type of radicals. At temperatures below 300°C, amorphous films are obtained which are independent of the reacting species. On the other hand, at higher deposition temperatures, (111)-preferred cubic TaN films are obtained when they react with ammonia plasma, while the reaction with hydrogen plasma produces amorphous films. All amorphous films obtained are recrystallized at an annealing temperature of 1000°C in an oxygen-containing (10%) ambient, showing (111) TaN, bcc Ta, and signals of orthorhombic Ta2O5. From detailed studies of film composition and chemical bonding in the obtained films, the impurity incorporation, especially carbon, is responsible for the dependence of film microstructures on different deposition conditions.

Syntheses and characterization of organoimido complexes of tantalum; potential single-source precursors to tantalum nitride

New single-source precursor to tantalum nitride thin films, (Bu t N)Ta(NEt 2) 3, and relate complexes, (RN)Ta(NEt 2) 3 (R = Pr i and Pr n), were prepared by reacting corresponding (RN)TaCl 3py 2 complexes (R = Bu t, Pr i and Pr n) with LiNEt 2 in hydrocarbon solvents. The structure of (Bu tN)TaCl 3py 2 was determined by X-ray crystallography.

Mechanical and tribological characterization of DC magnetron sputtered tantalum nitride thin films

Abstract Tantalum nitride (Ta x N 1− x ) coatings were deposited onto high-speed steel using reactive DC magnetron sputtering. Five different combinations of magnetron power and nitrogen flow were used. Phase analysis (XRD) revealed that the phase composition changes with increasing N 2 flow from a mixture of Ta and Ta 2 N to single phase Ta 2 N. This result was supported by GDOES analysis of the chemical composition. The coating hardness and residual stress were both found to increase with the amount of Ta 2 N in the coatings. In scratch testing, it was not possible to provoke adhesive failures at loads up to 100 N. Finally, the coating abrasion resistance was very high for all specimens and found to increase with the amount of Ta 2 N in the coatings.

High-temperature ceramic pressure sensor

A pressure microsensor for working at high temperature has been developed. The device consists of a tantalum nitride thin film, patterned on a Wheatstone bridge configuration, sputter-deposited onto thermally oxidized silicon wafers with an aluminium interconnection layer and a silicon dioxide passivation. The microsensors present a low temperature coefficient of resistance and good long-term stability. The sensitivity is 0.15 mV (V bar) −1 with low sensitivity drift and low combined non-linearity and hysteresis in the pressure range 0–10 bar.

Thin-film tantalum-nitride resistor technology for phosphide-based optoelectronics

The phosphide material system is an important material system for both microelectronics and optoelectronics, but integrated circuit technology on InP substrates is immature. In this work, thin-film deposition techniques and resistor processing techniques to fabricate fine-line geometry resistors for InP-based electronics are reported. Deposition parameters for d.c. reactive sputtering of tantalum in an argon-nitrogen ambient to realize tantalum nitride thin films with 50 Ωp[ sheet resistance are optimized. The dependence of electrical properties, including resistivity, Seebeck ratio and temperature coefficient of resistivity, are reported for a wide range of nitrogen flow. In common with other electronic material systems, Seebeck ratio characterization is implemented for process control monitoring of phosphide-based electronics fabrication. Material composition as a function of nitrogen flow is determined by Rutherford backscattering and elastic recoil detection. Techniques to fabricate low resistance contacts to the TaN are discussed. The processes are demonstrated with the fabrication of high-density, two-dimensional arrays of photoreceivers based on amplifiers using the tantalum nitrate resistor technology.

Effect of Thickness and Annealing on Stress in Tantalum and Tantalum Nitride Thin Film Hard Coatings

AbstractAn understanding of the relationship between stress and the other properties of thin films is extremely useful in the design of hard coatings for long term performance. In our earlier study, sputtered Ta and Ta(N) films were found to exhibit promising hard coating properties. For example, nano hardness as high as 30 GPa was observed in the nitride (pN2 = 0.100 mTorr) films. In this work, we study the variation in the stress in these films with respect to film thickness and annealing. Films in six different thicknesses (50, 250, 350, 500, 750, and 1000 nm) were deposited on oxide coated Si (111) wafers. Stresses in the films in the as-deposited state and as a function of temperature (300°C) were determined using a thin film stress measuring unit.

Effect of Thickness and Substrates on the Mechanical Properties of Tantalum and Tantalum Nitride Thin Films

AbstractDetermining the intrinsic mechanical properties of films by nanoindentation is complicated by the presence of the substrate. Generally, for very thin films (<100 nm) one unavoidably observes the properties of the film/substrate composite system. In order to determine the extent of the effect of the substrate on the mechanical properties of Ta and Ta-N thin films, we have grown these films in four different thicknesses (50, 250, 400 and 500 nm) and on three different substrates (glass, oxidized Si, and sapphire). The structure of the films was evaluated by x-ray diffraction and the mechanical properties (hardness and elastic modulus) were determined by nanoindentation.

Synthesis and Oxidation Kinetics of Sol-Gel and Sputtered Tantalum Nitride Thin Films

ABSTRACTTantalum nitride thin films were produced by nitridation of sol-gel tantala thin films. The oxidation kinetics and the activation energy for oxidation were investigated and compared to those of sputtered tantalum nitride thin films. Data was gathered from in situ sheet resistance measurements taken between 550 and 720 K. Sol-gel films exhibited parabolic oxidation kinetics and had an activation energy of 1.9 eV. Sputtered films displayed quartic oxidation kinetics at lower temperatures tending toward cubic kinetics at higher temperatures and had an activation energy of 1.6 eV.

AES and factor analysis study of the interaction of oxygen with tantalum and tantalum nitride thin films

AES and Factor Analysis (FA) have been used to characterize the interaction of oxygen with Ta and tantalum nitride thin films. Evidence is presented that the oxidation rate of tantalum is dependent on the nitrogen content in the film. In addition, AES and FA suggest the formation of tantalum oxynitride, upon oxygen exposure, on the tantalum nitride films.

Ceramic pressure sensor based on tantalum thin film

Abstract The properties of piezoresistive tantalum nitride thin films on silicon substrates have been investigated for use in a pressure-sensing element. The thin-film deposition has been carried out by reactive sputtering techniques under d.c. and r.f. power conditions. An r.f. reactive sputtered tantalum nitride thin film in an Ar-9%N2 deposition atmosphere has been selected as the ideal piezoresistive material for the strain gauge. This piezoresistive strain gauge combines a high resistivity, ϱ = 230 μΩ cm, a low temperature coefficient of resistance, TCR= − 80 ppm/°C and a high temporal stability with a good longitudinal gauge factor, GF = 3.5.

Micro-Mechanical Characterization of Tantalum Nitride Thin Films on Sapphire Substrates

ABSTRACTThe adhesion of Ta2N thin films – often used as thin film resistors – to sapphire substrates has been studied by continuous microindentation and microscratch techniques. Ta2N films, 0.1-0.63μm in thickness, were sputter deposited onto single crystal substrates. Continuous microscratch experiments were performed by driving a conical diamond indenter simultaneously into and across the film surface until stresses high enough to delaminate the film were developed. Continuous microindentation experiments were performed to induce film spallation by normal indentation. From both of these experiments, interfacial fracture toughness was determined as a function of film thickness. The interfacial fracture toughness obtained from continuous microscratch experiments is 0.53±0.17 MPa√m, independent of film thickness. This observation indicates that there is almost no plastic deformation in the film prior to fracture so that a ‘true’ interfacial fracture toughness is measured. For the 0.63 µm thick film, continuous microindentation data yielded a fracture toughness of 0.61 ±0.08 MPa√m, which matches closely the value obtained from the microscratch test. Hence, the continuous microscratch and microindentation techniques are viable methods for determining the interfacial fracture toughness in such bi-material systems.

The oxidation and resistance of tantalum-nitride thin films

The oxidation of reactively-sputtered, tantalum—nitride thin films has been studied between 473 and 773 K in air. Films with thicknesses that correspond to sheet resistances of 43, 75, and 150 Ω/□ were evaluated in this study. X-ray diffraction revealed that the films and the oxidation products were amorphous. The oxidation products were characterized with AES and XPS. The oxidation process was monitored by measuring the change in sheet resistance with time. Sheet resistance measurements were performed with a four-point probe. The oxidation kinetics can be represented by the equation ΔR/R n =k′t. ΔR/R is sheet resistance change in %, t is time, and k′ is the rate constant. The oxidation kinetics, for the thickest film, were parabolic above about 598 K, and approximately quartic below this temperature. The 75 Ω/□ films deviated from parabolic kinetics below 603 K, and approached approximate cubic kinetics at 498 K. However, the data were forced to fit parabolic kinetics with good correlation. For the thinnest film, no deviation from parabolic kinetics was observed. The rate constants obeyed the Arrhenius relation. An activation energy of 147 kJ/mole (1.52eV) was calculated, for the thickest film, during parabolic kinetics. This value is approximately equal to the activation energy obtained during quartic kinetics. A model that explains the deviation from parabolic to quartic oxidation kinetics at lower temperatures is presented. In this model, the change in resistance as a function of time was due to simultaneous change in film resistivity, as a result of oxygen dissolution into the film, and oxide-scale growth. The temperature at which this deviation occurs should be a function of film thickness.

Single-Source Precursors to Niobium Nitride and Tantalum Nitride Films

AbstractHerein we report our efforts to prepare new precursors to niobium nitride (NbN) and tantalum nitride (TAN, Ta3N5) thin films. Treatment of MC15 (M = Nb, Ta) with tertbutylamine in benzene solvent affords complexes of the formula [MCI2 (NtBu)(NHtBu)(NH2tBu)]2. The niobium complex [NbC12(NtBu)(NHtBu)- (NH2tBu)]2 affords NbN films on glass substrates between 500-600 °C, while the tantalum analog [TaC12(NtBu)(NHtBu)(NH2tBu)]2 gives films of Ta3N5 in this temperature range. Treatment of MCI5 (M = Nb, Ta) with 1,1-dimethylhydrazine in dichloromethane solvent affords complexes of the formula [MC12(NNMe2)(NHNMe2)(NH2NMe2)]n. These hydrazido complexes afford cubic MN films upon glass substrates at ≥400°C. Analyses of the films are presented.

Effect of hydrogen on deposition of tantalum nitride thin films from ethylimidotantalum complex

H 2 can affect the gowth of cubic TaN films from the organic precursors significantly. The growth rate of the film decreased with increasing H 2 concentration and increasing temperature of deposition

Deposition of tantalum nitride thin films from ethylimidotantalum complex

Croissance de couches minces de TaN sur un support Si par la methode LPCVD en utilisant des melanges d'ethyliminoethyl(C,N)tris(diethylamido)tantale et d'ethylimidotris(diethylamido)tantale

Stability of tantalum nitride thin film resistors

Post-deposition rapid vacuum annealing of tantalum nitride (Ta2N) thin film resistors (TFR) was successful in improving the temperature coefficient of resistance (TCR) to ±5 ppm/°C with starting TCR at about −140 ppm/°C. A subsequent aging study revealed degradation of the nichrome (NiCr) contact interlayer. Two improved contact layers, TiW and Tamelox (Ta/NiCr), were compared. The structural grain growth induced by the annealing effect resulted in Ta2N films having 100–1000 Å polycrystals in an amorphous matrix. The corresponding current conduction mechanisms were identified with a substrate-assisted tunneling model. The frequency response predicted potential applications to 100 GHz.

6112. Spectroscopic investigation of tantalum nitride thin film deposition by reactive sputtering in a triode system

6112. Spectroscopic investigation of tantalum nitride thin film deposition by reactive sputtering in a triode system