Chemical Vapor Deposition TiN Research Articles

Laser chemical vapour deposition of TiN and TiC films

Laser chemical vapour deposition (LCVD) of TiN and TiC films has been achieved by scanning linear deposition in a dynamic atmosphere on AISI 52100 bearing steel using TiCl 4, NH 3, C 2H 4 and H 2 as reactant gases induced by CO 2 laser. It has been found in our experiment that hydrogen played an important role in the LCVD TiN process. LCVD TiN film is golden in colour, single phase, stoichiometric in composition and homogeneously distributed. Preferential orientation of LCVD TiN film is correlated with deposition pressure. The microstructure of LCVD TiN film comprises about 2 μm equiaxial particles, each particle consisting of about 15 nm nanocrystalline grains. The average Knoop microhardness of LCVD TiN films is HK 1400 and the highest is HK 1602.3. The wear resistance of LCVD TiN film is four times that of the substrate. LCVD TiC film, with no preferential orientation, comprises homogeneous stoichiometric single-phase equiaxial particles.

Effects of adsorbates on step coverage in TiN chemical vapor deposition

Adsorbates in TiN chemical vapor deposition (CVD) using the TiCl4NH3 gas system are studied by the macro/microcavity method. At least, two types of adsorbates are found, which contribute to TiN growth. One is a slightly reactive molecule, which is considered to be the source gas itself. When it is the main reactant, good quality step coverage is obtained and a large number of Cl atoms remain in the grown film. The other is a radical, produced by the thermal decomposition of the slightly active molecule in the gas phase. Its large sticking coefficient causes poor step coverage and the amount of residual Cl atoms remaining in the film is relatively small. The ratio of the amount of these adsorbates on the film surface depends on the TiCl4 gas flow rate. This flow rate affects the growth rate, the amount of residual Cl in the grown film, and step coverage quality.

The Reaction of NH3 With TiN: Implications for CVD

ABSTRACTSince NH3 is an important component of TiN chemical vapor deposition (CVD) processes, understanding the NH3/TiN surface interaction is crucial to developing a model for the overall reaction. Temperature programmed desorption experiments show that NH3 adsorbs molecularly on amorphous TiN surfaces. Chemisorption occurs at only ∼5% of the surface sites, with an activation energy for desorption of 24 kcal/mol. The sticking probability into this state is 0.06 at 100 K. In addition, NH3 adsorbs with high probability into a multilayer state with an activation energy for desorption of 7.3 kcal/mol, similar to that found in other systems. NH3 does not dissociate on TiN. Under CVD conditions, however, the reactivity of NH3 on TiN may increase and surface reactions may play a part in film growth.

Thermal stability of thin poly-Si/Ta2O5/TiN capacitors for dynamic random access memory applications

Capacitors made up of thin films of Ta2O5/TiN on polysilicon have been studied for application to 256 Mbytes dynamic random access memories. In this study, the thermal stability of poly-Si/Ta2O5 films with TiN electrode film deposited by (i) chemical vapor deposition (CVD) with TiCl4 and NH3, (ii) sputtering, and (iii) metalorganic CVD (MOCVD) was compared. These samples were annealed under vacuum at 700, 800, and 900 °C for 30 min. The as-deposited and the annealed samples were analyzed by Rutherford backscattering with 2 MeV He+ ions. The CVD TiN films, which contained a small amount of Cl, provided pathways for the underlying Ta2O5 to out-diffuse during annealing at all temperatures between 700 and 900 °C. The sputtered films were resistant to the diffusion of Ta2O5 up to 800 °C, but relented at 900 °C, with measurable outdiffusion of Ta. There was no noticeable interaction of the Ta2O5 with the TiN layers, deposited by the MOCVD process, at temperatures up to 900 °C. However, the MOCVD TiN films were found to contain light elements such as carbon and oxygen, which were slightly reduced on annealing. Nuclear reaction analysis and secondary ion mass spectroscopy were used to detect the concentrations and depth profiles of light elements. These indicate presence of C and O contents up to at least 20 at. % in these films.

Homoleptic Tin and Silicon Amido Compounds as Precursors for Low-Temperature Atmospheric Pressure Chemical Vapor Deposition of Tin and Silicon Oxide Thin Films

Tin oxide films doped with fluorine or antimony are transparent conductors used in optoelectronic devices and solar cells. Silicon oxide thin films are used as diffusion barriers, passivation layers and dielectric layers in the microelectronics industry. Tin oxide thin films are commonly deposited in atmospheric pressure chemical vapor deposition (APCVD) processes by hydrolyzing SnCl[sub 4] or by reacting tetramethyltin with oxygen. The APCVD of silicon oxide films normally involves the reaction of ozone or oxygen with SiH[sub 4] or tetraethylorthosilicate. Gordon et al. recently reported the use of main-group amido complexes and ammonia as precursors in the APCVD of main-group nitride thin films. Because the amido precursors are volatile, easily synthesized, and relatively safe to handle, the authors decided to examine their use as precursors to main-group oxide thin films. This paper reports the successful APCVD of tin and silicon oxide from homoleptic dimethylamido complexes, M(NMe[sub 2])[sub 4] (M = Sn, Si), and oxygen at deposition temperatures ranging from 250 to 400[degrees]C. 14 refs., 2 figs., 1 tab.

Conformal Chemical Vapor Deposition TiN(111) Film Formation as an Underlayer of Al for Highly Reliable Interconnects

Chemical vapor deposition (CVD) TiN film having the (111) preferred orientation and conformal step coverage was developed for the first time. The key processes are predeposition of the Ti(002) layer before the CVD TiN film deposition and optimization of the flow rate of reactants: TiCl4, NH3 and H2. Growth of (111) crystal plane seems to be induced due to the lattice matching of crystal plane of the Ti film. On the other hand, conformal step coverage is obtained by using a lower flow rate of NH3, resulting in the surface-limited chemical reaction. It was also demonstrated that both sputtering and CVD Al, deposited on the CVD TiN having stronger (111) orientation, showed stronger (111) orientation which is advantageous for obtaining high electromigration (EM) resistance. Furthermore, simultaneous contact hole filling and interconnects formation using CVD Al/CVD TiN stacked film are successfully demonstrated.

Possibility of studying concentration profiles of reactive species during PACVD (hard coating) in an industrial set-up

The concentration profiles of the reactive species for plasma-enhanced chemical vapour deposition of TiN have been studied by optical emission spectroscopy (OES) in the spectral range from 300 to 800 nm. The low temperature deposition process of TiN/TiC from TiCl 4 is well known in small reactors, but until now the up-scale of this process is still a challenge. As shown in the literature it is well known that the process control parameter is the concentration of reactive Ti + in the plasma. The gas is a mixture of evaporated TiCl 4 nitrogen or methane, and hydrogen as the carrier gas. The OES in combination with a handling system for the spatially resolved measurement is a tool for detection and in-situ measurement of the reactive species in large reactors. The change in the concentration of the species depends on the injection of the gas mixture into the plasma and the influence of the process parameters on the reaction. The process parameters are also connected to the deposition rate, which change the concentration of reactive particles in the plasma too. The measurements were made in a cylindrical hot-wall reactor (of 600 mm diameter and 900 mm height). The results of our measurements show the concentration profiles as functions of the gas inlet system used.

Nucleation of CVD-TiN on tungsten

Using Chemical Vapor Deposition (CVD), TiN was deposited on sharp tungsten needles. The reactant gases were TiCl4, N2, and H2. A Transmission Electron Microscopy (TEM) investigation revealed that the first nuclei of the CVD–TiN coating on tungsten did not consist of δ–TiN, but were a mixture of α–TiN and δ–TiN. These results were also verified with x-ray measurements. From these experimental results a possible mechanism for the initial growth of TiN on tungsten is suggested. It may be that the change in relative concentrations of the different titanium nitrides suggested as mechanism of the initial growth of CVD–TiN can be applied in general for all TiCl4/H2/N2/metal systems where the original substrate surface material partly or completely consists of a metal with catalytic properties.

The influence of titanium interlayers on the adhesion of PVD TiN coatings on oxidized stainless steel substrates

It has been shown that the use of thin titanium interlayers improves the coating-substrate adhesion of physical vapour deposition (PVD) titanium nitride thin films on a stainless steel substrate. This improvement arises from a combination of chemical gettering and mechanical compliance effects. The improved adhesion of plasma-assisted chemical vapour deposition TiN coatings with increasing interlayer thickness has been shown to be largely attributable to the compliance effect (S.J. Bull, P.R. Chalker, C.F. Ayres and D.S. Rickersby, Mater. Sci. Eng. A, 139 (1991) 71). The development of practical methods to improve adhesion is hampered by the difficulties involved in quantitative measurements of the effect. To avoid the influence of the intrinsic and extrinsic parameters involved in scratch test and microhardness measurements, efforts have been made to apply fracture mechanical testing methods to the determination of the adhesion strength of the film on the substrate (S. Berg, S.W. Kim, V. Grajewski and E. Fromm, Mater. Sci. Eng. A, 139 (1991) 345). In our study the influence of Ti interlayers on the adhesion of PVD TiN coatings on oxidized stainless steel substrates was investigated using a pull-off test for adhesion measurements and scanning tunnelling microscopy and secondary ion mass spectrometry for analysis of the fractured surfaces. It was shown that the thickness of the Ti layer must be chosen according to the thickness of the oxide layer. An excess of Ti leads to lower adhesion values due to failure in the Ti layer, while a shortage of Ti leads to unreacted oxide and minimum adhesion due to brittle fracture in the oxide layer, which was shown to be amorphous.

Nucleation and growth of chemical vapor deposition TiN films on Si (100) as studied by total reflection x-ray fluorescence, atomic force microscopy, and Auger electron spectroscopy

We report for the first time the characteristics of the early growth of chemical vapor deposition (CVD) TiN films on Si (100) in the surface reaction limited regime, using total reflection x-ray fluorescence (TXRF), atomic force microscopy (AFM), and Auger electron spectroscopy (AES). Small amounts of CVD TiN from TiCl4 and NH3 reactants were deposited on Si (100) at 650 °C using a rapid thermal CVD system, at a total pressure of 155 mTorr. We examined these small amounts of CVD TiN by introducing TXRF as a tool for observing the initial stages of growth, and AFM for characterizing changes in the overall surface morphology. The nucleation and growth of the resulting CVD TiN films as determined by TXRF, AFM, and AES will be discussed.

Thin film properties of low-pressure chemical vapor deposition TiN barrier for ultra-large-scale integration applications

Titanium nitride films deposited by low-pressure chemical vapor deposition (LPCVD) on Si(100) using TiCl4 and NH3 as reactants, were investigated as a function of deposition temperature between 400 and 700 °C. LPCVD TiN depositions were carried out in a rapid thermal chemical vapor deposition system with a total deposition pressure of 155 mTorr. Stoichiometric TiN films were formed regardless of the deposition temperature and composition was uniform across the entire film. Depending on deposition temperature, varying amounts of chlorine (Cl) and oxygen (O) impurities are found in the TiN films. Films deposited at lower temperatures (400 and 550 °C) contained more than 5 at. % Cl, while the films produced at 700 °C contained as little as 1 at. % Cl. For the films deposited at 650 and 700 °C, the bulk of the TiN films is oxygen-free. LPCVD TiN deposition rates of 400 Å/min with no appreciable incubation time were routinely achieved. The LPCVD TiN deposition process is surface reaction controlled with an activation energy of 35 kJ/mol. Excellent TiN film conformality was observed. Electrical resistivity of the TiN films was found to decrease with increasing deposition temperature. Resistivity in the range of 85 μΩ cm was observed. Polycrystalline ∂-TiN phase with a preferred orientation of (200) was observed at all deposition temperatures. These TiN films have columnar grain structure. The TiN/Si interface is smooth, and no voids are observed at the silicon substrate interface, a prerequisite for good adhesion. An increase in the average grain size and lattice parameter was observed with increasing deposition temperature. While increasing the deposition temperature increases the TiN film growth rate, it also produces larger TiN grains and rougher surface morphology. The reliability of the TiN films as a diffusion barrier between aluminum and silicon was evaluated by diode leakage current measurements, which remained low after being thermally stressed up to 550 °C.

TiNCl formation during low-temperature, low-pressure chemical vapor deposition of TiN

We report for the first time the existence of the titanium nitride chloride (TiNCl) compound in low-temperature (400 °C) low-pressure chemical vapor deposition (LPCVD) TiN films deposited using TiCl4/NH3 chemistry. Thin-film x-ray diffraction and Auger electron spectroscopy was used in the film characterization. Physical, chemical, and electrical properties of the resulting low-temperature LPCVD TiN films are discussed.

Structure characterization of plasma-deposited TiN coatings

The plasma-assisted chemical vapour deposition of TiN on steel, silicon and glass substrates from a gaseous mixture of TiCl 4, N 2 and H 2 has been studied. The crystallinity and density of the TiN coatings were affected by the r.f. discharge power density. X-ray diffraction revealed that the films have a strong (200) orientation which increases on increasing the discharge power density, and scanning electron micrographs of the TiN films show that the columnar structure becomes more dense. By increasing the discharge power density, the coating microhardness increases up to a maximum, after which it decreases. This effect is attributed to the different chlorine content of the films, which shows a minimum when the microhardness is maximum.

Transmission electron microscopy studies of growth and interface structure of chemically vapour deposited TiC and TiN films on WCCo alloy subsrates

It is known that the interface structures between deposits and substrates and the growth microstructure of deposits are important factors in the wear resistance of coating films. TiN and TiC films prepared by the chemical vapour deposition (CVD) method on WCCo alloy substrates were investigated using transmission electron microscopy (TEM). The thin foil for TEM was prepared using cross-sectional techniques. CVD TiC and TiN seem to be directly bonded with WCCo alloy and η phase without any pores at the interface. Deposits were fine grained at the initial stage of deposition. As the thickness of a film increased, the grains of CVD TiN became elongated in the direction of the growth with a preferred 220 orientation. High resolution TEM revealed that the grains in CVD TiC were connected with each other without any second phases.

Evaluation of corrosion-erosion-resistant coatings for WC chokes used in heavy oil production

Several diffusion alloying, chemical vapor deposition (CVD) and ion implantation coatings on WC-Co and WC-Ni base materials were evaluated in a combined laboratory and field testing program. A slurry erosion test and field test, as well as analysis of material properties such as microhardness, fracture toughness and microstructure, were conducted. The WC-Co base material was found to be superior to WC-Ni. The CVD TiN on WC-Co base was the most erosion-corrosion-resistant coating followed by the CVD Al 2O 3 and a boron diffusion coating. The scaling resistance of the materials was also evaluated, and it was closely related to their erosion-corrosion resistance. The best materials displayed high resistance in the slurry erosion tests and improved surface microhardness. However, corrosion resistance, surface microstructure, microhardness and fracture toughness characteristics can significantly alter this relationship. The broad laboratory and field testing program was found to be useful in the evaluation of the materials.

ChemInform Abstract: Growth and Properties of LPCVD Titanium Nitride as a Diffusion Barrier for Silicon Device Technology.

Chemical vapor deposition of TiN on Si wafers is carried out in a cold wall reactor at pressures in the range 100-300 mtorr and temp. between 450 °C and 700 °C using TiCl4 and NH3 as reactants.

Early Growth in the Chemical Vapor Deposition of Tin and TiC and Monitoring by Laser Scattering

AbstractThe early growth of chemically vapor deposited TiN and TiC coatings on pyrolytic graphite was studied in the kinetic- and mass transport-controlled regimes. While steady-state growth of these coatings results in columnar grains, such morphologies do not originate at the substrate/coating interface. Rather, TiC deposition begins on the substrate as fine grains less than 100 nm in diameter. Early TiN growth occurs in layers of 50 nm grains. In both cases, early fine-grained growth occurs at a lower rate than the linear, steady rate observed for columnar growth. A laser scattering technique has been developed as a tool for characterizing early growth through surface roughness. This noncontact method can be used as an in-situ diagnostic to detect changes in the surface of the growing deposit.

The effect of argon during the plasma-assisted chemical vapor deposition of TiN

The effect of argon during the plasma-assisted chemical vapor deposition of TiN

Plasma-assisted chemical vapour deposition of TiN and TiC on steel: Properties of coatings

TiN and TiC coatings were deposited onto M2 steel and pure iron at temperatures lower than 550 °C by a d.c. glow discharge method using an apparatus similar to the conventional apparatus for ion nitriding of steel. The micro Vickers' hardnesses of the coatings with a chlorine content of less than 5 wt.% were about 2000 and 3000 for TiN and TiC respectively. The hardness decreased with increasing chlorine content. Furthermore, the hardness of the TiC coatings was reduced by the excess carbon. X-ray diffraction lines corresponding to NH 4Cl appeared for the TiN coatings in which the chlorine content exceeded about 10 wt.%. A rolling test with slip showed that the adhesion strength of these hard coatings was superior to that of the TiN coatings formed by ion plating. Comparison of the two kinds of coatings obtained by this process showed that the TiC coatings were more adherent than the TiN coatings. The coatings had an outstanding resistance to wear and galling, as good as that of other hard coatings made by other methods such as ion plating, chemical vapour deposition and salt bath immersion.

High Temperature microhardness of hard coatings produced by physical and chemical vapor deposition

The microhardness of hard coatings of TiN and HfN prepared by chemical vapor deposition (CVD) and TiN, HfN, ZrN and TiAlN prepared by physical vapor deposition (PVD) were measured between room temperature and 1000°C. The microhardness of the PVD coatings was significantly higher than that of the CVD counterparts at room temperature but all microhardness values tended to converge at 1000°C. Higher N: Ti ratios were found in PVD TiN relative to CVD TiN. X-ray diffraction measurements indicated that the PVD coatings contained high residual compressive growth stresses associated with lattice distortion and very fine grain size, which were confirmed using transmission electron microscopy. Low residual stresses in high temperature CVD coatings are caused by thermal expansion mismatch between coating and substrate. Differences in grain morphology and crystal texture are attributed to varying conditions of energetic bombardment and deposition temperature in the several PVD methods employed. The faster decrease in microhardness with temperature in PVD coatings is caused by the high residual energy and finer grain size.