Chemical Vapor Deposition Titanium Nitride Research Articles

Influence of nitrogen gas over microstructural, vibrational and mechanical properties of CVD Titanium nitride (TiN) thin film coating

In this experimental investigation, the influence of different N2 gas flow rates on different properties (e.g. morphological, mechanical, etc.) of chemical vapor deposited (CVD) Titanium nitride (TiN) coatings has been discussed. The TiN coatings had been grown on Si (100) substrate at elevated temperature (1000 °C) using Titanium dioxide (TiO2) powder. SEM images reveal a dense uniform microstructure with an irregular surface pattern. The surface roughness of the coatings was found to be increased from 12.42 to 28.56 nm with an increase in flow rate. XRD results indicate a B1 NaCl crystal structure of the film with reduced crystallite size with the increasing N2 flow rate. Through the corrosion test, it has been observed that due to the variation of N2 flow rate the corrosion resistance of the films decreases with increasing N2 flow rate. The mismatch of thermal expansion co-efficient in between Si substrate and TiN thin film reduces with higher N2 flow rate. The acoustic and optic phonon mode of TiN coatings have been shifted to higher intensities with higher N2 flow rate. The mechanical properties of the film reveal that the maximum value of hardness (H) and Young's modulus (E) are 30.14 and 471.85 GPa respectively.

Application of a Novel CVD TiN Coating on a Biomedical Co-Cr Alloy: An Evaluation of Coating Layer and Substrate Characteristics.

Titanium nitride (TiN) was deposited on the surface of a cobalt–chromium (Co–Cr) alloy by a hot-wall type chemical vapor deposition (CVD) reactor at 850 °C, and the coating characteristics were compared with those of a physical vapor deposition (PVD) TiN coating deposited on the same alloy at 450 °C. Neither coating showed any reactions at the interface. The face-centered cubic (fcc) structure of the alloy was changed into a hexagonal close-packed (hcp) phase, and recrystallization occurred over at 10 μm of depth from the surface after CVD coating. Characteristic precipitates were also generated incrementally depending on the depth, unlike the precipitates in the matrix of the as-cast alloy. On the other hand, the microstructure and phase of the PVD-coated alloy did not change. Depth-dependent nano-hardness measurements showed a greater increase in hardness in the recrystallization zone of the CVD-coated alloy than in the bulk center of the alloy. The CVD coating showed superior adhesion to the PVD coating in the progressive scratch test. The as-cast, PVD-coated, and CVD-coated alloys all showed negative cytotoxicity. Within the limitations of this study, CVD TiN coating to biomedical Co–Cr alloy may be considered a promising alternative to PVD technique.

Effect of Contact Plug Deposition Conditions on Junction Leakage and Contact Resistance in Multilevel CMOS Logic Interconnection Device.

Here, we developed the optimal conditions in terms of physical and electrical characteristics of the barrier and tungsten (W) deposition process of a contact module, which is the segment connecting the device and the multi-layer metallization (MLM) metal line in the development of 100 nm-class logic devices. To confirm its applicability to the logic contact of barrier and W films, a contact hole was formed, first to check the bottom coverage and the filling status of each film, then to check the electrical resistance and leakage characteristics to analyze the optimal conditions. At an aspect ratio of 3.89:1, ionized metal plasma (IMP) Ti had a bottom coverage of 40.9% and chemical vapor deposition (CVD) titanium nitride (TiN) of 76.2%, confirming that it was possible to apply the process to 100 nm logic contacts. W filling was confirmed, and a salicide etching rate (using Radio Frequency (RF) etch) of 13–18 Å/s at a 3.53:1 aspect ratio was applied. The etching rate on the thermal oxide plate was 9 Å/s. As the RF etch amount increased from 50–100 Å, the P active resistance increased by 0.5–1 Ω. The resistance also increased as the amount of IMP Ti deposition increased to 300 Å. A measurement of the borderless contact junction leakage current indicated that the current in the P + N well increased by more than an order of magnitude when IMP Ti 250 Å or more was deposited. The contact resistance value was 0.5 Ω. An AC bias improved the IMP Ti deposition rate by 10% in bottom coverage, but there was no significant difference in contact resistance. In the case of applying IMP TiN, the overall contact resistance decreased to 2 Ω compared to CVD TiN, but the distribution characteristics were poor. The best results were obtained under the conditions of RF etch 50 Å, IMP Ti 200 Å, and CVD TiN 2 × 50 Å.

Characterization of CVD TiN coating at different deposition temperatures and its application in hydrocarbon pyrolysis

In this study, titanium nitride (TiN) coatings at different deposition temperatures have been designed as anti-coking coatings during cyclohexane steam pyrolysis. The TiN coatings were deposited on 310S foils (10mm×10mm×0.9mm) between 750 and 950°C by a chemical vapor deposition (CVD) method. To evaluate the anti-coking property of TiN coatings, cyclohexane was employed for cracking in a tubular quartz reactor. The as-deposited and coked TiN coatings were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, Raman spectroscopy and X-ray diffraction. The results show that the deposition temperature has a great influence on the morphology and microstructure of CVD TiN coatings. The structures of TiN coatings with apparent differences tend to lie on (220) preferred orientation as the deposition temperature increases. When the deposition temperature is below 850°C, the TiN coatings cannot cover the substrate surface completely and some filamentous coke was observed. However, the anti-coking ratios of TiN coatings at different deposition temperatures are all above 90% during cyclohexane pyrolysis at 770°C for 1.5h. In summary, the TiN coatings at high deposition temperatures can completely cover the cracks and gaps on the rough surface of blank substrate, and thus provide a very good protective layer to prevent the substrate from metal dusting and severe coking. Moreover, the Raman spectra show that the dust-like coke on the surface of TiN coatings has a higher degree of graphitization than the filamentous coke on 310S substrate, which also proves the good anti-coking performance of TiN coatings.

Effect of N 2/H 2 plasma treatment on the moisture adsorption of MOCVD–TiN films

In the application of contact glue layer for semiconductor devices, a nitrogen/hydrogen (N 2/H 2) plasma treatment is usually used to reduce the amount of C and O impurities of metallorganic chemical vapor deposition titanium nitride (MOCVD–TiN) films. This study found that the sheet resistance of as-deposited MOCVD–TiN film without N 2/H 2 plasma treatment dramatically increased with exposure time due to moisture adsorption. Increasing plasma treatment power and time was able to retard the increase in sheet resistance. From residue gas analysis at 200 °C, it was found that the amount of H 2O outgases from the MOCVD–TiN films decreased with increasing plasma treatment power and time. TEM images reveal that the surface of the MOCVD–TiN films became compact as it received more plasma treatment energy, making it difficult for the external moisture to diffuse into and react with the MOCVD–TiN films.

Diffusion Control Techniques for TiN Stacked Metal Gate Electrodes for p-Type Metal Insulator Semiconductor Field Effect Transistors

We have investigated a polycrystalline silicon (poly-Si)/chemical vapor deposited titanium nitride (CVD-TiN) stacked structure as a metal gate with a high-k for p-type metal insulator semiconductor field effect transistors (p-MISFETs). A divided-CVD method provided an appropriate effective work function (4.9–5.2 eV) on HfSiON for p-MISFETs. However, the deposition of poly-Si on CVD-TiN films shifted the effective work function to a midgap (∼4.6 eV), and Ti, Hf, and Si diffused into poly-Si/CVD-TiN/high-k structures during poly-Si deposition. Then, we found that an increase in the deposition temperature of CVD-TiN films and the insertion of a physical vapor deposited (PVD)-TiN film between the poly-Si and CVD-TiN layers are effective in suppressing these diffusions. In particular, the insertion of the PVD-TiN film provided an appropriate effective work function of 4.9 eV. Therefore, we found that the diffusion control techniques for poly-Si/TiN/high-k stacked structures are highly effective for obtaining the appropriate work function for p-MISFETs.

Thermal Decomposition of Tetrakis(ethylmethylamido) Titanium for Chemical Vapor Deposition of Titanium Nitride

The thermal decomposition of tetrakis(ethylmethylamido) titanium (TEMAT) has been investigated in Ar and H 2 gas atmospheres at gas temperatures of 100-400 °C by using Fourier Transform infrared spectroscopy (FTIR) as a fundamental study for the chemical vapor deposition (CVD) of titanium nitride (TiN) thin film. The activation energy for the decomposition of TEMAT was estimated to be 10.92 kcal/mol and the reaction order was determined to be the first order. The decomposition behavior of TEMAT was affected by ambient gases. TEMAT was decomposed into the intermediate forms of imine (C=N) compounds in Ar and H 2 atmosphere, but additional nitrile (RC≡N) compound was observed only in H 2 atmosphere. The decomposition rate of TEMAT under H 2 atmosphere was slower than that in Ar atmosphere, which resulted in the extension of the regime of the surface reaction control in the CVD TiN process.

Plasma-Over-Treatment Model on Patterned Nanometer MOCVD-TiN Contact Glue Layer

In the application of contact glue layer for semiconductor devices, a hydrogen/nitrogen plasma treatment was used to improve the electrical properties of metallorganic chemical vapor deposition titanium nitride (MOCVD-TiN) films. In this study, the optimum contact resistance (Rc) was found in 0.11-μm logic patterned wafers while increasing the plasma treatment energy on the TiN glue layers. Unsatisfactory plasma treatment resulted in a higher Rc because of insufficient impurity removal from the TiN films. The plasma under-treatment behavior of patterned TiN films was similar to that of blanket TiN films. When the TiN films received overloaded plasma energy, the plasma over-treatment effect caused an increase in the Rc of patterned wafers but a decrease in the film resistivity of blanket TiN films. A novel plasma-over-treatment model suggested that a decrease in the numbers of grains in patterned TiN films reduced the numbers of parallel current channels leading to a higher Rc.

Effects of plasma treatment in the tungsten process for chemical vapor deposition titanium nitride barrier film beyond nanometer technology

As the device shrunk to100 nm, the CVD TiN barrier filling would be limited by the process window of contact for both step coverage and plasma treatment. This limitation not only affects the step coverage capability but also poses a challenge to the treatment of the organic film with the small contact hole. In this study, we investigated whether the plasma treatment of the TiN film barrier influences the subsequent tungsten deposition and causes the change of the gapfilling behavior. After the different RF plasma treatment, we found that the resistivity and impurity level of the thin TiN film can influence not only the contact resistance and uniformity, but also the product yield. The over-treatment contacts were found with porous voids in the poor tungsten deposition during the contact filling even after CMP polishing. The resistances of under-treatment contacts would be determined by the impurity level of TiN films. Hence, the optimized TiN deposition and treatment would be critical to the contact resistance and yield performance.

Plasma induced microstructural, compositional, and resistivity changes in ultrathin chemical vapor deposited titanium nitride films

Extremely thin titanium nitride (TiN) barrier layers for Cu based interconnects were deposited using metal organic chemical vapor deposition. The effect of the subsequently performed nitrogen/hydrogen plasma treatment on the microstructure, composition, and electrical properties of these films is studied using conventional and high resolution transmission electron microscopy, Auger electron spectroscopy, and four point probe resistivity measurements. In the studied system the crystallization of the TiN film starts from an amorphous matrix and a polycrystalline morphology is developed upon the H2/N2 plasma treatment. After a short plasma treatment, most of the film is already crystalline and consists of grains of a few nanometers in diameter. Continued plasma treatment leads to grain growth and a significant reduction of contaminants such as oxygen and carbon. The resistivity of the films drops with plasma treatment time, and a correlation between resistivity and oxygen content is found, which suggests that oxygen in the grain boundaries plays a decisive role for the resistivity of the films. It is shown that the oxygen in the grain boundaries leads to an electron reflectance of 0.9. Thus, the oxygen accumulation in the grain boundaries is the limiting factor for the reduction of film resistivity by plasma treatment.

Remote plasma enhanced metalorganic chemical vapor deposition of TiN from tetrakis-dimethyl-amido-titanium

Effect of H2 and N2 plasma in the remote plasma enhanced metalorganic chemical vapor deposition of TiN (titanium nitride) from tetrakis-dimethyl-amido-titanium was studied in the deposition temperature range of 200–400 °C. The deposition rate with H2 plasma is faster than with N2 plasma and both processes showed similar activation energies, 16.7 and 18.3 kcal/mol, in the deposition temperature range of 200–300 °C. Above this temperature range, the deposition rate was decreased due to the gas phase dissociation of the precursor. H2 plasma was effective in removing hydrocarbon impurities and carbon was incorporated as a form of TiC but with N2 plasma, TiN film was formed with rough surface due to the incorporation of free carbon. The film with H2 plasma showed low resistivity due to the lower incorporation of free carbon.

The role of kinetics in the nucleation and void formation in copper films produced by chemical vapor deposition

The heterogeneous nucleation and subsequent growth of chemical vapor deposited copper using hexafluoroacetylacetonate-Cu(I)-trimethylvinylsilane on physical vapor deposited tantalum and chemical vapor deposited titanium nitride was studied by means of electron microscopy and atomic force microscopy. It was found that the nucleation densities are about two orders of magnitude higher on TiN than on Ta. This leads to an increased roughness of films deposited on Ta compared to those produced on TiN. Moreover, the Cu films on the Ta substrate show a large number of voids, whereas no such voids were observable in the Cu films deposited on top of TiN. A simplified model for the influence of gas-surface reaction and surface self-diffusion on the shape of the Cu grains was developed. This model, which is supported by the experimental data, shows that if the grain shape changes from spherical to nonspherical before coalescence with neighboring grains, voids occur. A critical grain size and nucleation density of about 150 nm and 5×1013 m−2, respectively, were calculated for the deposition conditions used in this work.

Effects of Barrier-Metal Schemes of Tungsten Plugs and Blanket Film Deposition

This work investigates the effects of various contact integration schemes on tungsten (W) plug formation. The deposition rate, surface morphology, sheet resistance and reflectivity of W deposited on various substrates are also characterized. Experimental results indicate that the titanium nitride (TiN) film which does not undergo post-rapid-thermal-processing (RTP) treatment has a higher W deposition rate than TiN film which under goes the post-RTP treatment. The W plug formed on chemical vapor deposition (CVD) TiN has easily found voids, which result in high contact resistance. To reveal the relationship of CVD TiN process conditions and W plug loss, process variables including film thickness, plasma ambient, in situ plasma treatment periods and cycles are tested. According to these results, plasma ambient has a strong influence on W plug loss during the etch-back process. In addition, the electrical characteristics of various contact integration schemes are examined in terms of both n+ and p+ contact resistance. This work also proposes a superior contact integration scheme to achieve low contact resistance and high production efficiency.

Comparison study of physical vapor-deposited and chemical vapor-deposited titanium nitride thin films using X-ray photoelectron spectroscopy

The chemical compositions of physical vapor-deposited (PVD) and chemical vapor-deposited (CVD) titanium nitride (TiN) thin films were investigated by X-ray photoelectron spectroscopy (XPS). The effect of a H2/N2 plasma treatment on the chemical composition of CVD TiN thin film was also evaluated. The wafers were air-exposed before the XPS analysis. XPS depth profiles show that the PVD TiN has a N/Ti ratio of 1:1 with a small amount of oxygen in the film (less than 5 at.%). Significant amounts (∼20 at.%, respectively) of carbon and oxygen were observed in the air-exposed CVD TiN thin film, which has a N/Ti ratio of 0.5:1. The H2/N2 plasma treatment greatly reduced the carbon content in the CVD TiN thin film (less than 10 at.%) and a N/Ti ratio of 1:1 was achieved. High resolution XPS spectra indicate that the oxygen in all three TiN thin films analyzed was chemically bonded to Ti. The C1s peak of the as-deposited CVD TiN thin film was resolved into two peaks with binding energies of 282.2 and 284.7 eV, corresponding to the chemical states of carbide and organic carbon. After the H2/N2 plasma treatment, most of the organic carbon was removed with the remaining carbon present mainly as carbide in the CVD TiN thin film.

Study of the ignition behavior of a pulsed dc discharge used for plasma-assisted chemical-vapor deposition

An investigation of a pulsed dc discharge used for plasma-assisted chemical-vapor deposition of titanium nitride has been performed in order to understand the nonuniformity of quality and thickness of the deposited films. The experiments have been performed using a gateable image intensifier to study the temporal and spatial light intensity of the discharge. Additionally, a single Langmuir probe has been used to study the temporal evolution of the plasma potential and the charged particle density. The influence of varying parameters like geometry, gas composition, voltage, pressure, duration of the pulses, etc., on the spreading of the plasma has been investigated. Our experiments reveal that in the presence of electronegative species like TiCl4, which is a source gas for the production of titanium nitride, the spreading of the discharge along the substrates is slow, reaching some parts of the reactor with substantial delay. The result is a nonuniform plasma power density in front of the cathode as well as a spatially varying exposure time of the surface to the plasma. These effects are the reason for the inhomogeneity of the deposited films. The experiments revealed that the slow spreading of the discharge is accompanied with low local cathode fall voltages. The problems with the slow spreading of the discharge can be solved by measures which increase the conductivity of the plasma at the beginning of the pulses. The effectiveness of such measures has been studied.

Integrated barrier/plug fill schemes for high aspect ratio Gb DRAM contact metallization

New contact fill integration schemes were developed for high aspect ratio Gb DRAM contact metallization. Integration schemes for both tungsten-plug contacts and aluminum-plug contacts were studied. For tungsten-plug contacts, various types of titanium liners and titanium nitride barriers were investigated and evaluated. These included collimated PVD (physical vapor deposition) titanium, ion metal plasma (IMP) titanium, and CVD (chemical vapor deposition) titanium liners; plasma enhanced CVD (PECVD) titanium nitride and plasma enhanced MOCVD (ECVD) titanium nitride barriers. The electrical results of 0.3 μm, 5:1 aspect ratio (AR) contact structures processed with a TiCl 4-based CVD titanium liner and plasma enhanced CVD titanium nitride barrier show the lowest and the most tightly distributed contact parametrics. This is attributed to the conformal nature of the CVD process. In addition, the high titanium-deposition temperature, which leads to a simultaneous titanium silicide formation during the CVD titanium deposition process, may also have attribution to the low contact resistance and diode leakage obtained. In the case of aluminum-plug contacts, two different types of titanium nitride barriers (ECVD titanium nitride vs. silane-treated MOCVD titanium nitride) were evaluated and both showed comparable contact parametrics.

Improved Conformality of CVD Titanium Nitride Films

AbstractWe demonstrate a novel approach to improving the step coverage of thin films made by chemical vapor deposition (CVD). Titanium nitride (TiN) films were deposited by atmospheric pressure CVD using tetrakis(diethylamido)titanium vapor (TDEAT) and ammonia gas (NH3) carried in nitrogen gas. Trimethylamine (NMe3) gas was added during some of the depositions. The substrates were patterned silicon wafers having holes with aspect ratio of 3.5 through a silicon dioxide layer. We discovered that the step coverage was significantly increased for TiN films made with NMe3. At 320 °C, the step coverage was increased from 70% to nearly 100%. Within the range of deposition temperatures used in our study, 320 °C to 370 °C, the amount of improvement increased as the deposition temperature decreased. The trimethylamine did not increase the resistivity or the impurity levels in the films, but it did reduce the growth rate slightly. We suggest that the trimethylamine adsorbs onto the surface, temporarily blocking some of the sites on which growth could take place. Thus the effective sticking coefficients for the precursors are decreased, and the step coverage is increased.

ChemInform Abstract: Metallization of Polymers Using Plasma‐Enhanced Chemical Vapor Deposited Titanium Nitride as Interlayer.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Metallization of Polymers Using Plasma‐Enhanced Chemical Vapor Deposited Titanium Nitride as Interlayer

A low‐temperature process for titanium nitride (TiN) deposition by means of an electron cyclotron resonance plasma chemical vapor deposition process was applied to poly(tetrafluoroethylene), polyimide, benzocyclobutene, and poly(butyleneterephthalate). The organometallic compounds tetrakis(dimethylamido)titanium or titanium(IV)isopropoxide introduced into the downstream region of a nitrogen electron cyclotron resonance plasma were used as precursors for TiN deposition at 100°C. The thin TiN film (thickness 15 to 30 nm) acts as a conductive interlayer for the electroplating process or as adhesion promoter for sputtered titanium films. Prior to the deposition of the interlayer, the samples were treated on a biased susceptor with argon ions to enhance the adhesion of the TiN interlayer. This metallization procedure avoids the use of toxic and pollutive etching agents for polymer activation as well as a electroless metal deposition. The maximum adhesion of the electroplated copper on poly(tetrafluoroethylene) and poly(butyleneterephthalate) was established to be 13 and , respectively. For sputtered Ti films on polyimide and benzocyclobutene, maximum adhesion was 16 and , respectively. As shown by atomic force microscopy, TiN grains were formed on the polymer surface. Film composition was investigated by secondary ion mass spectrometry.

Barrier Properties of Titanium Nitride Films Grown by Low Temperature Chemical Vapor Deposition from Titanium Tetraiodide

Results are presented from a systematic study of the composition, texture, and electrical properties of titanium nitride (TiN) films and their performance as diffusion barrier in multilevel interconnect schemes of ultralarge scale integration (ULSI) computer chip device structures. The films were grown by low temperature (<450°C) inorganic chemical vapor deposition using titanium tetraiodide as source precursor and ammonia and hydrogen as co‐reactants. The TiN films were nitrogen‐rich., with iodine concentrations below 2 atom percent, displayed resistivities in the range 100 to 150 μΩ cm depending on thickness, and exhibited excellent step coverage with better than 90% conformality in both nominal 0.45 μm, 3:1 aspect ratio and 0.25 μm, 4:1 aspect ratio contact structures. A comparison of the properties of chemical vapor deposited (CVD) TiN with equivalent physical vapor deposited (PVD) TiN showed that reactivity with Al‐0.5 a/o Cu alloys was equivalent in both cases. In particular, a 10% increase in the Al‐Cu/TiN stack sheet resistance was observed for both types of TiN after a 450°C, 30 min sinter. Similarly, the characteristics of CVD tungsten and reflow plug fills were identical on both types of TiN films. However, barrier performance for CVD TiN in aluminum and tungsten plug technologies was superior to that of PVD TiN, as evidenced by lower contact diode leakage for CVD TiN in comparison with PVD TiN films of equal thickness. This improved barrier performance could be attributed to a combination of factors, which include the nitrogen‐rich composition, higher density, and enhanced conformality of the CVD TiN phase in comparison with the PVD TiN. In view of the superior step coverage and diffusion barrier characteristics, the low temperature inorganic CVD route to TiN seems to provide an adequate replacement for conventional PVD TiN in emerging ULSI metallization interconnect schemes.