PVD TiN Films Research Articles

Study of ferroelectric characteristics of Hf0.5Zr0.5O2 thin films grown on sputtered or atomic-layer-deposited TiN bottom electrodes

Ferroelectric Hf0.5Zr0.5O2 (HZO) films were grown by the atomic layer deposition (ALD) technique on an ALD or physical-vapor-deposited (PVD, sputtering) TiN bottom electrode (BE). The PVD TiN film showed small grains with flat surface morphology, mainly consisting of the (111) crystallographic plane. In contrast, the ALD TiN film exhibited a larger diameter and faceted grain shapes, with the (200) crystallographic surface planes. The 10-nm-thick HZO film on the ALD TiN BE showed a lower internal field, enhanced endurance (>1 × 1010 cycle at 2.5 MV/cm), and decreased leakage current than identical HZO films on the PVD TiN BE. Lower interfacial oxidation of the ALD TiN BE as a result of the smaller grain boundary area of the ALD TiN induced a lower defect density in the HZO film. The higher work function of the ALD TiN film also contributed to the lowering of the leakage current.

Investigating the structure and tribo-mechanical performance of PVD TiN on bearing TiN substrate constructed by rf plasma

Abstract Recent study was focused on conjoining rf plasma nitriding of titanium with TiN coating by rf plasma magnetron sputtering as a duplex treatment technique. To develop the tribo-mechanical characteristics and load bearing capacity of titanium substrate, rf plasma nitriding was engaged to predestine a bearing TiN layer on Ti base substrate. The PVD process was accomplished employing TiN target in argon plasma atmosphere. All PVD parameters were constant excluding the deposition time which was varied from 4 to 20 min with deposition rate of ∼60–65 nm/min. The effect of PVD TiN film thickness which was varied from 240 to 1300 nm on structure, tribo-mechanical and electrochemical performance of TiN/TiN duplex coatings was investigated. It was found, the duplex treatment expressively increased the PVD TiN/TiN coatings hardness (max: 2600 ± 47 HV0.025) and constricted the substrate plastic deformation. An enhancement in the adhesion in the duplex TiN/TiN samples compared to TiN/Ti was observed. Moreover, the wear, friction (reduced to nearly 0.2) and the corrosion performance were markedly upgraded for the duplex treated samples compared with pure Ti and PVD TiN/Ti.

Influence of substrate stiffness and of PVD parameters on the microstructure and tension fracture characteristics of TiN thin films

Titanium nitride is widely used as wear resistant coating thin films in industrial parts. Mechanically they correspond to nanometric 2D ceramic systems which are bound to a much thicker metallic substrate. Under uniaxial tension these films respond by forming a periodic array of cracks. The separation between the cracks is primarily defined by the strength and stiffness of the film. Secondary factors, as the elastic properties of the substrate, or the microstructure and/or induction of residual stresses during processing may also have and effect. In the present work PVD TiN films were deposited by triode magnetron sputtering in Brass and Aluminum substrates. The deposition characteristics of the films were varied by changing the bias potential and the nitrogen supply during deposition (constant or variable). Tension fractures were observed in situ using a traveling microscope and under nanoindentation/scratching tests. Energy Filtered TEM was used to access the nitrogen levels across film thickness. The results were correlated with the film residual stress levels obtained in the different deposition conditions.

Ambient and elevated temperature properties of TiN, TiAlN and TiSiN PVD films and their impact on the cutting performance of coated carbide tools

The cutting performance of hardmetal inserts coated with PVD TiN, TiAlN and TiSiN films was investigated by innovative analytical–experimental methods, for explaining the effect of coating properties on coated tool wear in milling. Nanoindentation results were evaluated by FEM-supported algorithms for determining the stress–strain constitutive laws of the applied films. According to these laws, the TiSiN films possess enhanced mechanical properties in comparison to TiAlN and TiN coatings. Moreover, in perpendicular impact experiments at various temperatures, the TiSiN films exhibited the best resistance and fatigue behaviour. Additionally, Rockwell C indentations and inclined impact tests were performed to assess qualitatively and quantitatively the films' adhesion on the substrate. These tests revealed a deteriorated adhesion of the TiSiN coating compared to the corresponding ones of the other two films. Finally, by FEM-supported calculations of the material removal process in milling, the mechanical and thermal loadings of the cutting edge were estimated and insight was provided concerning the effect of coating adhesion, mechanical properties and fatigue on the cutting performance. The deterioration of the adhesion of the TiSiN films on the substrate led to a cutting performance reduction in milling compared to the one achieved with TiAlN coated hardmetal inserts.

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.

Surface properties and microstructure of implanted TiN films using MEVVA ion source

The PVD–TiN film was implanted with titanium and nitrogen ions and the improvement in surface wear resistance was investigated. Ti ion implantation was done using a metal vapor vacuum arc (MEVVA) ion source with an implantation dose of 2 × 10 16 ions/cm 2 and at an extraction voltage of 48 kV. The wear characteristics of the implanted samples were measured and compared with the performance of the unimplanted one by a pin-on-disc apparatus and an optical interference microscope. The structures of the samples were observed by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). A dynamic TRIM called as TRIDYN was used to calculate the concentration depth profiles of implanted ions in TiN to investigate wear resistance mechanisms. The results showed that the improved wear resistance of the TiN film was mainly due to forming of nano-order TiN crystal grains in a thick amorphous layer and the decreased local state number of Ti after Ti ion implantation.

Characterization of electrical and crystallographic properties of metal layers at deca-nanometer scale using Kelvin probe force microscope

As device dimensions are scaled down, the variations of electrical and chemical properties within metal electrodes have a critical impact on MOSFETs and Metal/Insulator/Metal (MIM) capacitors characteristics. In this letter, we report on Work Function (WF) measurements performed at deca-nanometer scale using Kelvin probe Force Microscope (KFM). We first demonstrated the relationship between the WF value and the grain crystallographic orientation by combining KFM and Electron Back Scattered Diffraction (EBSD) performed over the same Cu area. Once this relationship was established, KFM was used to provide, in addition to the WF value, the crystallographic properties of PVD TiN films grown on various substrates. Finally we measured an increase of 0.26 eV of the WF of TiN grown by CVD after N 2/H 2 plasma treatment. In the latter case, the modification of the bulk chemical potential by post-treatment has been proposed.

Hot filament chemical vapour deposition and wear resistance of diamond films on WC-Co substrates coated using PVD-arc deposition technique

Different Cr- and Ti-base films were deposited using PVD-arc deposition onto WC-Co substrates, and multilayered coatings were obtained from the superimposition of diamond coatings, deposited on the PVD interlayer using hot filament chemical vapour deposition (HFCVD). The behaviour of PVD-arc deposited CrN and CrC interlayers between diamond and WC-Co substrates was studied and compared to TiN, TiC, and Ti(C,N) interlayers. Tribological tests with alternative sliding motion were carried out to check the multilayer (PVD + diamond) film adhesion on WC-Co substrate. Multilayer films obtained using PVD arc, characterised by large surface droplets, demonstrated good wear resistance, while diamond deposited on smooth PVD TiN films was not adherent. Multilayered Ti(C,N) + diamond film samples generally showed poor wear resistance. Diamond adhesion on Cr-based PVD coatings deposited on WC-Co substrate was good. In particular, CrN interlayers improved diamond film properties and 6 μm-thick diamond films deposited on CrN showed excellent wear behaviour characterised by the absence of measurable wear volume after sling tests. Good diamond adhesion on Cr-based PVD films has been attributed to chromium carbide formation on PVD film surfaces during the CVD process.

A New Approach for Studying Mechanical Properties of Thin Surface Layers Affected by Manufacturing Processes

Nano-indentation has become an important tool in the study of mechanical properties of solids at small length scales, ever since its formulation as a technique in the early 1980s. The small size of an indentation, typically one micrometer or less in surface extent, makes it a potentially attractive tool also for the quantitative study of the characteristics of surface layers in monolithic solids. Here, we report results from a study in which nano-indentation has been combined with taper-sectioning to analyze the mechanical properties of thin surface layers affected by manufacturing processes. The so-called white etching layer (WL) produced in steel surfaces by machining and abrasion is characterized. The WL is found to have a hardness in the range of 11.5–16.2 GPa, which is significantly greater than that of untempered martensite produced by heat treatment processes. These hardness values are close to those measured on steel piano wires. The so-called “burn-layer” produced on ground surfaces of steels is found to have a hardness distribution very similar to that of a white layer, suggesting that the two layers are of the same type. Localized hardening and softening of surface layers, over spatial extents of a few micro-meters, caused by material removal processes are accurately resolved by the combined use of nano-indentation and taper-sectioning. The taper-sectioning/nano-indentation approach is also shown to be a good procedure for characterizing the hardness of PVD-TiN films deposited onto hard metal substrates.

The effects of MEVVA ion implantation on the tribological properties of PVD-TiN films deposited on steel substrates

The effects of post-deposition metal vapour vacuum arc (MEVVA) ion implantation into TiN films were studied as part of a continuous effort to improve the wear performance of coatings used for cutting tools. This is a first account on the tribological behaviour of PVD-TiN coatings deposited on steel substrates and treated by MEVVA ion implantation. Two types of species were selected, C and W, one light and one heavy. In all cases, after implantation, tribological improvements were observed: The friction coefficient of the PVD-TiN against ruby was significantly reduced from 0.75 to 0.18 with carbon implantation at a dose of 10 17 cm −2 and the lifetime to spalling was improved by more than 200%. (Untreated films detached after approx. 5000 cycles, whereas implanted films were still well adhered after 19 000 cycles.) For C-implanted samples, an increase in nano-hardness in the near surface region was also observed. These effects are attributed to the formation of a carbonaceous layer on the surface, accompanied by the formation of TiC in the sub-surface region, as detected by XRD. In contrast, W implantation improved coating wear life, but not friction coefficient or nano-hardness. The results are compared to those obtained for MEVVA implantation into CVD-TiN and to conventional implantation.

An investigation into the performance of diffusion barrier materials against copper diffusion using metal-oxide-semiconductor (MOS) capacitor structures

Cu/SiO 2/Si capacitors were fabricated, with and without barrier layers between the copper and the oxide, and the dielectric properties of the 100 nm thermal SiO 2 layers monitored after high temperature stressing. Film properties were also examined by X-ray diffraction spectroscopy (XRD) and atomic force microscopy (AFM). Diffusion barriers of Ti, TiN, TiN/Ti, Ta and TaN/Ta were assessed for thermal stability and ability to prevent Cu diffusion. These evaluations indicated that a 10 nm PVD TiN film is a good barrier against Cu diffusion up to 550°C, whilst the addition of a thin Ti layer allows the TiN barrier to withstand a 600°C 60 s anneal. Ta and its nitrides were assessed and found to fail at temperatures as low as 400°C.

Characterization of TiN films alternately treated with PVD and Cr ion implantation

The projected ranges of the conventional ion implantation are generally below submicrons. This makes it difficult to apply the implantation techniques to the tribological uses. The combined process of the physical vapor deposition (PVD) and the ion implantation was developed to form the thick implanted layers over a few microns. In this process, firstly, the PVD films are deposited by the cathodic arc ion plating method with a film thickness of 50 to 250 nm. Secondly, the metal ions are implanted using the pulsed arc ion source at an energy below 80 keV without mass separation. These two processes were alternately conducted up to the film thickness of a few microns. Using this combined process, Cr implanted PVD-TiN films were studied. The film thicknesses of the implanted layers were 2–7 μm, which are over ten times larger than those of conventionally implanted layers. Furthermore, these films showed excellent wear resistances compared with the unimplanted PVD-TiN films.

The Effect of Impurities in Tin Film When Used As Mos Gate Electrodes

ABSTRACTRefractory metal gates have been studied for CMOS gate electrodes on ultra thin gate oxide due to its midgap work function, low resistivity and no gate depletion, etc. In particular, titanium nitride received most attention because of its process maturity and its good diffusion barrier properties for backend applications. Different TiN film properties are important when TiN is used as a gate material than when it is used for backend applications. One issue is the effect of TiN film impurities on the gate oxides and their high temperature stability since some high temperature processes are usually needed after gate formation. This paper reports the study of different TiN films used as MOS gate electrodes on ultra thin gate oxide and the effects of their impurities on gate oxide electrical performance. PVD TiN films deposited with different process conditions show different oxygen content, and different gate oxide properties were observed when these PVD TiN films were used as gate electrodes. On the other hand CVD TiN films deposited using different precursors also showed different impurities, including carbon, oxygen or silicon, which largely affect CVD TiN performance when used as gate material. The different TiN films were characterized by X-ray glancing angle reflection, XPS, SIMS and TEM, and the electrical properties were studied by I-V, C-V, charge to breakdown (Qbd) and ramp voltage breakdown tests on MOS capacitors. The results showed that the high purity TiN films provide stable gate material with small damage to the gate oxide, but impurities, especially oxygen, affect the gate oxide properties after high temperature anneal. However, due to the different TiN process capabilities, TiN films with impurities may still have advantages over pure TiN film in some cases of different MOS gate applications.

Optimizing Sputtered Tin ARC Film Properties for Lithography of Sub-0.25μm Interconnect

ABSTRACTAdvanced interconnect fabrication may require alternative TiITiN processes, such as an ionized metal plasma (IMP) sputtering technique to deposit Ti/TiN liner for sufficient step coverage in high aspect ratio contacts/vias. Since TiN is also widely used as an anti-reflective coating on top of multilayer metal films, the optical properties of the TiN film are extremely important.In this paper, both IMP and standard PVD TiN films deposited on an aluminum layer are compared with respect to their lithography performance at exposure wavelengths of 365 nm (i-line) and 248 un (deep ultraviolet, or DUV). The measured optical constants of the two films were found to be very similar. The linewidth response of these two films at 365 nm was comparable; however, with DUV patterning, resist footing was observed on both films; but was especially severe with standard TiN. Differences in resist profile are explained in terms of the surface structure and density of the TiN film. By varying the conditions for deposition of IMP TiN (such as, RF bias, chamber pressure, etc.), the optical properties of the films may be varied. The impact of these varying film properties on DUV lithography is evaluated. Experimentally obtained linewidth response is compared with optical lithography simulations.

WC-Co合金上に蒸着したTiC, TiN被膜の成長および界面組織

Using the transmission electron microscope, the growth morphology, orientation relationships and interface structure have been investigated for TiC and TiN films deposited on WC-Co alloys by chemical or physical vapor deposition (CVD or PVD). CVD-TiC films on the WC-Co alloys were grown in granular form and their interfaces were irregular. The TiC/WC orientation relationship was given as (0001)WC\varparallel(1\bar11)TiC and [\bar1100]WC\varparallel[\bar112]TiC. PVD-TiN films on WC-Co alloy were grown in columnar form. TiN grains showed particular orientation relationships with WC grains. One of the relationships was the same as that observed for TiC/WC, and the other was [0001]WC\varparallel[1\bar10]TiN, (10\bar10)WC\varparallel(111)TiN. CVD-TiN films on the WC-Co alloys showed the change in growth morphology from the granual form at the initial stage of growth to the columnar form.

Structural Investigation of Ti-N Films

ABSTRACTTi-N films were deposited by reactive ion plating on various substrates. The N/Ti-ratio was systematically varied in order to produce films of varying structure and properties from pure titanium to overstoichiometric TiN. Broad diffraction peaks typical of PVD Ti-N films were found. Metastable ct-titanium was observed over a wide range up to about 50 at. % N. No marked differences in the phase composition or in the crystallographic texture could be found in the films deposited on the various substrates. The hardness of the films was observed to increase with increasing nitrogen content, reaching a maximum around 35 – 40 at. % N corresponding to a mixed ε-Ti2N and δ-TiN structure. Extended annealing at 773 K did not result in any major phase transformations. After annealing at 1173 K, α-Ti could no longer be found in nitrogen-rich films. Also ε-Ti2 N transformed to δ-TiN after annealing at 1173 K for 2 h.