Atomic Layer Deposition TiN Research Articles

Synthesis of high conformalty Ti-Six-N films using (CH3)3CCl and SiH4; density functional theory simulation and film characterization

The step coverage of the atomic layer deposition (ALD) of Ti-N thin films was improved by the addition of (CH3)3CCl, and Si atoms were added during the Ti-N deposition to form a Ti-Six-N thin film. By ALD, four to eight cycles of the gas (CH3)3CCl/TiCl4/NH3 formed the Ti-N layer and, subsequently, one to two cycles of the gas SiH4/NH3 added Si atoms to formed the Ti-Six-N layer. The ALD process was repeated to form a thin film Ti-Six-N 150 Å (bilayer of (Ti-N) 80 Å + (Six-N) 70 Å) while adjusting the amounts of (CH3)3CCl and SiH4. The crystallinity of Ti-N was studied by X-ray diffraction (XRD), and its composition was studied using X-ray photoelectron spectroscopy and secondary ion mass spectrometry. The composition of the Ti-Six-N film was studied using electron energy loss spectroscopy and selected area electron diffraction, and its roughness was confirmed using atomic force microscopy. Transmission electron microscope was used to measures the thickness and composition of the Ti-Six-N film through location in a test pattern with an aspect ratio of 50:1. Step coverage improved to 99.9 % compared to conventional ALD Ti-N when using (CH3)3CCl. Additionally, (CH3)3CCl was more effective at lower temperatures (460 °C compared to 530 °C), and the effect of the (CH3)3CCl flow rate was saturated above 300 sccm.As the amount of (CH3)3CCl increased, the growth per cycle decreased from 0.29 Å/cycle to 0.15 Å/cycle. The addition of Si to the Ti-N film facilitated leakage gain by increasing the difference in the work function between the electrode and the capacitor, material but may have the side effect of pillar bending due to a decrease in crystallinity and hardness. We verified that the XRD (200)/(111) peak ratio decreased as the Si content increased. As a result, the optimal conditions for electrode Ti-Six-N were confirmed as follows: 300 sccm (CH3)3CCl Ti-N, SiH4 10 sccm Six-N combination.Furthermore, the Ti-Six-N layer can serve as the bottom electrode of a capacitor reduce the manufacturing process steps, and be a candidate for a solution for the electrode of the capacitor of a 5 nm node memory device.

Growth Mechanism and Film Properties of Atomic-Layer-Deposited Titanium Oxysulfide

In this work, atomic layer deposition (ALD) has been employed to prepare titanium oxysulfide (TiOxSy) thin films. Compositional control was achieved through a supercycle approach, where the ALD processes of TiOx and TiSx were interleaved. ALD was performed at 100, 150, and 200 °C, and tetrakis(dimethylamino)titanium (TDMAT), H2S, and H2O were used as precursors. It is shown that the conductivity and transparency of the film are highly tunable by controlling the composition of TiOxSy between pure TiSx and TiOx. Specifically, the incorporation of S enables the film resistivity to be reduced by up to 6 orders of magnitude, while the visible light absorption is increased significantly. It is furthermore shown that the resulting films are significantly more oxygen-rich than would be expected on the basis of the supercycle ratio, an effect which is more pronounced at higher deposition temperatures. Through mass spectrometry and in situ ellipsometry studies, this low S content is shown to originate from exchange reactions where S is replaced by O on the growth (sub)surface during H2O exposure. This is contrary to the common finding for ALD zinc, indium, and tin oxysulfide films, for which exchange reactions are known to favor S-rich films. These exchange reactions are shown to be more prominent at higher deposition temperatures and to persist until approximately 3–5 Å of TiOx has formed.

In Situ and Ex Situ diagnostics of ALD-Ultrathin Lithium-Ion Films

All solid-state ion layers has an ever-growing interest in order to accomplish on-chip energy storage devices. As such, lithium-ion synaptic transistor to build artificial neural networks, integrated area-enhanced capacitors and lithium-ion microbatteries for energy supply are suitable candidates fulfilling energy-efficient devices. Atomic layer deposition (ALD) is one of the most promising techniques for manufacturing ultrathin layers for lithium-ion devices with exceptional capabilities to enable conformal growth at atomic scale. In this area, in situ diagnostics has become of vital importance for the growth process understanding especially on view of the air-sensitivity character of lithium ultra-thin layers.The purpose of this work is to present an in situ spectroscopic ellipsometry (SE) study of ALD thin films used on the fabrication of lithium-ion devices. We will consider several aspects of ALD ultrathin films growth, such as film thickness, saturation curves and initial films nucleation. We shall compare in situ SE results with those of ex situ diagnostics such as XRR (x-ray reflectometry) and XPS (x-ray photoelectron spectroscopy).We focus on the characterization of 10-100 nm thin lithium phosphate electrolyte with and without nitrogen doping deposited at ALD temperature range 300-350°C using LiHMDS-TMPO and LiHMDS-DEPA precursors, respectively. On the other hand, the realization of silicon integrated lithium ionic devices requires the implementation of essential barrier films to prevent Li-ion into the Si substrate. We will explore here the ability of titanium nitride depositions to act as lithium-ion diffusion barriers. TiN deposition (10-20 nm thin) by ALD process (350°C-400°C) uses TiCl4 and NH3 precursors.First, we investigate the growth process of LiPO, LiPON and TiN intrinsic layers deposited using thermal ALD. Secondly, we apply in situ and ex situ diagnostics on exemplary LiPO/LiPON deposited on top of the 10 nm ALD TiN film (Figure 1: Monitoring of LiPON thickness vs deposition time using in-situ Ellipsometry). The film thickness deduced from in situ SE measurements was corroborated by thickness measurements with XRR technique (Figure 2: Evolution of LiPON thickness vs ALD cycles using Ellipsometry and SE characterization techniques). Ex situ SE was used most often for WiW uniformity evaluating (Figure 3: 8” Wafer thickness mapping of ALD LiPON layers (a: 10nm TiN film; b: 17nm LiPON film). The preliminary results underline the fact that ALD growth rate and nucleation of lithium electrolyte and titanium nitride obviously depends on the ALD process parameters (temperature, pulse and purge times, number of cycles) but on the substrate nature (silicon, thermal oxide, and metallic). In situ and ex situ diagnostics highlight that initial film growth of lithium electrolytes and TiN layers strongly depends on the precursors kind used in the ALD process and the substrate material employed. Figure 1

Atomic layer deposited TiN capping layer for sub-10 nm ferroelectric Hf0.5Zr0.5O2 with large remnant polarization and low thermal budget

Ferroelectric Hf0.5Zr0.5O2 (HZO) thin films has attracted a large amount of interests in academia and industry. The scaling of the HZO thickness down to the sub-10 nm region with a low thermal budget is essential in practical applications. However, pronounced ferroelectricity in sub-10 nm HZO thin films prepared at a low process temperature is rarely reported. In this paper, significant ferroelectricity is reported in 6 nm HZO thin films by the TiN capping electrode prepared by atomic layer deposition (ALD). Capping the ALD TiN layer leads to the crystallization of an as-deposited amorphous HZO thin film to the ferroelectric orthorhombic phase. The post-annealing treatment at a low temperature of 400 °C contributes to a record remnant polarization (2Pr) of ∼ 51.2 μC/cm2 in sub-10 nm HZO. The mechanisms of the TiN capping effect are investigated based on the TiN capping layers prepared by ALD and sputtering. The distinct ferroelectric properties can be attributed to the formation of a large in-plane tensile stress and the TiOxNy mixed phase by the ALD TiN capping layer. The realization of the low thermal budget and high 2Pr in sub-10 nm HZO thin films by the ALD TiN capping layer is highly promising for next-generation ferroelectric applications.

Ferroelectric HfZrO2 With Electrode Engineering and Stimulation Schemes as Symmetric Analog Synaptic Weight Element for Deep Neural Network Training

Atomic layer deposition (ALD)-based TiN electrode on ferroelectric HfZrO2 metal/ferroelectric/metal (MFM) capacitor and ferroelectric field-effect transistor (FeFET) is demonstrated experimentally with weight transfer, that is, $\Delta {P}$ , per pulse analysis through consecutive alternating potentiation/depression (Pot./Dep.) training pulses. The weight training pulse schemes are studied to have symmetric and linear synapse weight transfer to increase the accuracy and accelerate the deep neural network (DNN) training. With ALD TiN inserted, $\alpha _{p} / \alpha _{d} = -0.63$ / −0.84, asymmetry $\vert \alpha _{p} - \alpha _{d}\vert =0.21$ , and polarization modulation ratio (Pot./Dep.) = 97%/98% are achieved for MFM capacitor, and $\alpha _{p} / \alpha _{d} = -1.32$ / −1.88, asymmetry $\vert \alpha _{p} - \alpha _{d}\vert =0.56$ , and $G_{\text {max}} / G_{\text {min}} > 10\times $ are delivered for FeFET.

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.

Strategies for Reducing Particle Defects in Ti and TiN Thin-Film Deposition Processes

Generation of particle defects in semiconductor manufacturing is inevitable, but it has to be minimized to enhance IC yield. There are various causes for the generation of particle defects in different semiconductor manufacturing processes, such as diffusion, thin-film deposition, lithography, etch, and clean. In this paper, primary defect generation mechanisms in thin-film deposition processes, such as atomic layer deposition TiN, radio frequency physical vapor deposition Ti, and physical vapor deposition TiN, are discussed. Various strategies, such as periodic clean optimization, on-load clean, idle pasting, periodic pasting optimization, kit life optimization, target burning optimization, and kit hardware selection that reduce the generation of defects in the thin-film deposition processes are presented. This paper also discusses hardware-induced surface defect and solutions to reduce them.

Annealing of thin “Tincone” films, a tin-based hybrid material deposited by molecular layer deposition, in reducing, inert, and oxidizing atmospheres

Molecular layer deposition of hybrid organic–inorganic thin films called “tincones” is achieved using tetrakisdimethylaminotin as the metal precursor and glycerol (GL) as the organic reactant. The GL-based process displays linear growth and self-limiting surface reactions in a broad temperature window ranging from 75 to 200 °C. At higher temperatures, no film growth is possible. The growth per cycle decreases rapidly with increasing temperature from 1.3 Å at 75 °C to less than 0.1 Å at 200 °C. The films are observed to be smooth with scanning electron microscopy and atomic force microscopy. The hybrid organic–inorganic nature of the films is visible in both infrared spectroscopy and x-ray photoelectron spectroscopy. As deposited tincone films are annealed in reducing (H2), inert (He), or oxidizing (O2) atmospheres. In situ x-ray diffraction is employed to study the crystallization of the films during annealing. Tincone films annealed in reducing or inert atmosphere crystallize into a tetragonal SnO phase at 388 and 410 °C, respectively. These temperatures are lower than the crystallization temperature of 480 °C for atomic layer deposition (ALD) tin oxide films annealed in H2. Tincone films annealed in oxygen crystallize into an SnO2 phase at a temperature of 523 °C, which is similar to the crystallization temperature for ALD tin oxide films annealed in He or O2. This reduced temperature for crystallization into SnO for the tincone films is interesting since SnO is one of the few metal oxides known as a p-type semiconductor material.

Cobalt titanium nitride amorphous metal alloys by atomic layer deposition

The formation of thin amorphous cobalt titanium nitride (CoTiN) layers was investigated using a supercycle method of atomic layer deposition (ALD). The stoichiometry of the resultant ALD CoTiN films was controlled by changing the ratio of Co and TiN thicknesses. X-ray diffraction analysis and transmission electron microscopy observations showed that the microstructure of the ALD Co and TiN was transformed from polycrystalline to amorphous CoTiN. The stoichiometry of the CoTiN layer was affected by the growth characteristics of ALD Co and TiN on each surface. The results revealed that ALD TiN undergoes nucleation incubation on the ALD Co surface, whereas ALD Co does not undergo nucleation incubation on the ALD TiN surface. The properties of the amorphous CoTiN layers were evaluated by diffusion experiments and mechanical tests. Because of the lack of grain boundaries, the CoTiN efficiently blocks the diffusion of Cu at elevated temperatures and exhibits higher hardness compared with ALD Co.

Influence of Oxide Interlayer by TiN Metal Gate in High-k First CMOS Devices

Due to its good film stability and electric property of high effective work function, TiN film has been widely used as high-k gate dielectric capping layer or work function metal in advanced High-k/metal gate CMOS devices. In this work, different TiN films were prepared by atomic layer deposition (ALD) and plasma vapor deposition (PVD) respectively, their thermal stability and interaction with gate stack films were investigated. Furthermore, their impacts on interface properties of interfacial oxide/high-k and interfacial oxide/silicon were also studied. The results show that both ALD and PVD TiN films have good thermal stability, while they tend to gather oxygen from atmosphere during sequential process steps. After high temperature annealing, the gathered oxygen in TiN film is easy to diffuse upward into TiN/poly-Si interface to form a thin TiSixOy layer above TiN film, and diffuse downward through high-k dielectric film resulting in interfacial oxide layer (IL) regrowth.

Electrically Scaled Hafnium Oxide Based Ge Devices

HfxZr1-xO2 (0≤x≤1) films with different Hf/(Hf+Zr) ratios were deposited on Al2O3 passivated Ge by atomic layer deposition (ALD) combined with a cyclical deposition and annealing scheme (termed DADA) in which an annealing was performed after every 20 ALD cycles. A post microwave plasma treatment was conducted after the high-k deposition. Metal oxide semiconductor capacitors (MOSCAPs) using ALD TiN metal gates were fabricated to investigate the electrical properties of the ALD HfxZr1-xO2 thin films. The electrical measurements show significant electrical benefits compared to samples that were not deposited using method described above. The electrical results were corroborated by synchrotron X-ray diffraction measurement

Microscratch testing method for systematic evaluation of the adhesion of atomic layer deposited thin films on silicon

The scratch test method is widely used for adhesion evaluation of thin films and coatings. Usual critical load criteria designed for scratch testing of coatings were not applicable to thin atomic layer deposition (ALD) films on silicon wafers. Thus, the bases for critical load evaluation were established and the critical loads suitable for ALD coating adhesion evaluation on silicon wafers were determined in this paper as LCSi1, LCSi2, LCALD1, and LCALD2, representing the failure points of the silicon substrate and the coating delamination points of the ALD coating. The adhesion performance of the ALD Al2O3, TiO2, TiN, and TaCN+Ru coatings with a thickness range between 20 and 600 nm and deposition temperature between 30 and 410 °C on silicon wafers was investigated. In addition, the impact of the annealing process after deposition on adhesion was evaluated for selected cases. The tests carried out using scratch and Scotch tape test showed that the coating deposition and annealing temperature, thickness of the coating, and surface pretreatments of the Si wafer had an impact on the adhesion performance of the ALD coatings on the silicon wafer. There was also an improved load carrying capacity due to Al2O3, the magnitude of which depended on the coating thickness and the deposition temperature. The tape tests were carried out for selected coatings as a comparison. The results show that the scratch test is a useful and applicable tool for adhesion evaluation of ALD coatings, even when carried out for thin (20 nm thick) coatings.

Fabrication of ion conductive tin oxide-phosphate amorphous thin films by atomic layer deposition

This work reports the atomic layer deposition (ALD) of tin oxide-phosphate films using tetrakis(dimethylamino)tin and trimethyl phosphate as precursors. The growth rates were 1.23–1.84 Å/cycle depending upon the deposition temperature and precursor combination. The ionic conductivity of the ALD tin oxide-phosphate films was evaluated by cross-plane impedance measurements in the temperature range of 50–300 °C under atmospheric air, with the highest conductivity measured as 1.92 × 10−5 S cm−1 at 300 °C. Furthermore, high-resolution x-ray photoelectron spectroscopy exhibited two O1s peaks that were classified as two subpeaks of hydroxyl ions and oxygen ions, revealing that the quantity of hydroxyl ions in the ALD tin oxide-phosphate films influences their ionic conductivity.

Oxide Structure-Dependent Interfacial Layer Defects of HfAlO/SiO2/Si Stack Analyzed by Conductance Method

Aggressive downscaling of effective oxide thickness (EOT) requires improvement in gate leakage current and interfacial characteristics. Recently other materials like Al, Zr, and La are introduced into HfO2 to further reduce the EOT and improve the reliability. Since the structure of the HfO2-based dielectric changes with addition such materials it is required that the impact of structural change on the interface needs to be investigated. In addition, the effect series resistance（R s）associated with the substrate and contact needs to be excluded. In this work we have used metal oxide semiconductor capacitor (MOS-C) devices of 3nm HfAlO/ 0.5nm SiO2/Si gate stack by different preparation methods (different Al doping, post annealing temperatures, deposition stacks) to characterize the quality of interface. Interface defect densities were evaluated by conductance method (1) while excluding any series resistance effect. 13 samples were prepared with 5 angstrom of interfacial layer SiOx, intentionally deposited on the Si substrate by vapor ozone treatment prior to depositing the high-k layer by atomic layer deposition (ALD) in a 300 mm TEL Trias™ cleanroom tool at TEL Technology Center. The metal gate was prepared by 5nm ALD TiN followed by 50nm physical vapor deposition (PVD) TiN. The substrate was of p-type Si (001) orientation with a.doping concentration of approximately 1015cm-3. Small signal capacitance and conductance measurements were investigated by HP4284 LCR analyzer. It is known that depending on the post-deposition annealing (PDA) temperatures Al doped HfO2 changes its structure from amorphous to tetragonal reducing its EOT (2). It was observed that D it is dependent on the EOT of hafnium aluminum oxide. The amorphous structure has the lowest D it (2.76) whereas tetragonal HfO2 (t-HfO2) has the highest D it (1.27). The Dit values of other EOT are within the range of observed highest and lowest values as EOT, as shown in Fig.1. It is expected that D it value are affected both by the oxide phase structure and interfacial layer thickness since Aluminum doping could impede the growth of the interfacial layer. The decrease in interfacial layer will significantly impact the interface defects as they are closer to interface, this was observed when annealing temperature was 800°C (3). However, in the low annealing temperature with addition of Al the dielectric constant of oxide decreases insignificantly to changed EOT without reducing Dit . E. H. Nicollian and A. Goetzberger, Bell Syst. Tech. J. 46, 1055 (1967).K. Tapily, S. Consiglio, R. Clark, R. Vasic, C. Wajda, J. Jordan-Sweet, G. Leusink, and A.C Diebold, ECS Trans., 64 (9), 123 (2014).Y.Sugimotoa, H.Adachia, K.Yamamotoa, D.Wangb,H. Nakashimaa, H. Nakashima, Material Sci. in Semicon. Process.,9, 1031 (2006). Figure 1

Mitigation of Reverse Short-Channel Effect With Multilayer TiN/Ti/TiN Metal Gates in Gate Last PMOSFETs

This letter investigates the mitigation of reverse short-channel effect (RSCE) using multilayer atomic layer deposition (ALD) TiN/PVD Ti/CVD TiN metal gates (MG) for the p-channel metal-oxide-semiconductor field-effect transistors fabricated the by gate-last process. It is found that work function (WF) of multilayer ALD titanium nitride/physical vapor deposition titanium/chemical vapor deposition titanium nitride (ALD TiN/PVD Ti/CVD TiN) MG in devices of short channels is larger than in devices of long channels. This mainly results from different ALD TiN crystal orientations for devices with different gate lengths, that is, TiN(100) for devices with short gate length, whereas TiN(111) for devices with long gate length. The WF of ALD TiN(100) is larger than TiN(111). Meanwhile, because of the property of PVD sputtering, the Ti layer is thinner in devices of short channels than in devices of long channels. Our results on MOSCAP show that the flat-band voltage (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">fb</sub> ) for TiN MG with a Ti layer is reduced by 0.2 V. Taking all the aforementioned into account, V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> roll-up is suppressed as the gate length shrinks, leading to the mitigation of RSCE.

Electrodeposition and Characterization of Manganese Dioxide Thin Films on Silicon Pillar Arrays for 3D Thin-Film Lithium-Ion Batteries

Due to the increasing power requirements of the electronic devices and emerging technologies (e.g., wireless transmission), Li-ion batteries should be improved to provide higher energy and power densities on a small area (e.g. <1 cm2). To date, one promising way to maximize the energy and power densities of battery is to be built using 3D structured electrodes. Such electrodes are designed to make shorter ions diffusion paths and improving electrons harvesting pathways [1,2].In this context, the present work focuses onthe electrochemical deposition of manganese dioxide thin films on high aspect ratio silicon pillar arrays coated with carbon as a technologically-relevant current collector and the investigation of their properties as positive electrode material for Li-ions batteries. As 3D electrode array, hexagonally arranged Si pillars of 2um in diameter and 2um spacing were etched 60um deep in the silicon by reactive ion etching (RIE) using a SiO2 hard mask. The pillars were coated with about 20nm TiN by atomic layer deposition (ALD), acting as diffusion barrier for lithium into silicon. Cases of conformal coatings of electrolytic manganese dioxide (EMD) directly on the conductive TiN barrier were compared with seeded TiN / silicon pillars. In this respect, thin carbon coatings were evaluated as technological relevant alternative for platinum. For this, about 30nm of carbon was grown on ALD TiN / silicon pillars by chemical vapor deposition (CVD) from CH4/H2 mixture. The platinum seed films were made by ALD process. The electrolytic manganese dioxide (EMD) films were anodically deposited from an aqueous solution of 0.3 M MnSO4·xH2O + 0.55 M H2SO4. Since the oxidation of TiN takes place in the same potential region as does EMD deposition a protective layer such as platinum can be used to prevent TiN from oxidation during the aqueous deposition of MnO2 [3]. Here we evaluated carbon as technologically relevant alternative. Figure 1 shows cyclic voltamogrammes for uncoated and carbon coated planar TiN substrates. The EMD film thickness on TiN is strongly limited due to oxidation of the TiN. The carbon successfully protects the TiN from oxidation such that much thicker films can be made similarly to what was found with Pt seed layers before [4].The physical characteristics of the EMD films has been primarily investigated on planar substrates. The crystal structure of the EMD films before and after lithiation were characterized by X-ray diffraction (XRD). The porosity of the EMD films was determined by comparison of Rutherford backscattering (RBS) and Scanning electron microscopy (SEM). The porosity of the films typically ranges between 40-60%, depending on film thickness and substrate.After removing the water content in the films by thermal annealing, the electrochemical activity of EMD films was studied in propylene carbonate solvent with 1M LiClO4.Reversible insertion and extraction of Li+ was observed. Electrochemical lithiation and delithiation experiments showed an improved cycle performance for carbon coated TiN substrates compared to Pt coated TiN substrates. The difference is attributed to decreased porosity (attachment) for the EMD to the C surface compared to platinum surface. The average lithium storage capacity for planar EMD films is about 50mAh/cm2 per mm (at 10mV/s comparable with charging rate of 20C). Based on a surface area gain of 28for the 3D pillar structures, a capacity of 0.2mAh/cm2is expected for conformal coated 200 nm film at these high rates.REFERENCES[1] M. Roberts, P. Johns, J. Owen, D. Brandell, K. Edström, G. Enany, C. Guery, D. Golodnitsky, M. Lacey, C. Lecoeur, H. Mazor, E. Peled, E. Perre, M. M. Shaijumon, P. Simon, P. L. Taberna, J. Mater. Chem. 21, 9876 (2011)[2] A. H. Whitehead and M. Schreiber, Journal of The Electrochemical Society, 152, A2105 (2005) [3] D. J. Cott, M. Verheijen, O. Richard, I. Radu, S. De Gendt, S. van Elshocht, and P. M. Vereecken, Carbon, 58 59 (2013).[4] "Effect of Film Morphology on the Li-ion Intercalation Kinetics in Anodic Porous Manganese Dioxide Thin-Films" A. Etman, A. Radisic, E. Mahmoud, C. Huyghebaert, P.M. Vereecken, submitted to Journal of Physical Chemistry.

ALD TiN Barrier Metal for pMOS Devices With a Chemical Oxide Interfacial Layer for 20-nm Technology Node

We propose the use of atomic layer deposition (ALD) TiN barrier to replace physical vapor deposition TiN barrier for high- k last/gate last pMOS devices with a chemical oxide interfacial layer in 20-nm technology node. It was found that the pMOS devices with ALD TiN exhibit lower gate leakage current density (Jg) and equivalent oxide thickness. Furthermore, it was found that we could achieve larger flat-band voltage (Vfb) and larger equivalent work function from the pMOS devices with ALD TiN barrier. It was also found that we could further improve the performances of the fabricated pMOS devices by increasing the ALD TiN thickness from 2 to 3 nm.

Highly-Conformal TiN Thin Films Grown by Thermal and Plasma-Enhanced Atomic Layer Deposition

Atomic layer deposition (ALD) was used to synthesize highly-conformal titanium nitride thin films using both thermal activation at 250°C and plasma activation at 200°C. Tetrakisdimethylaminotitanium (TDMAT) and ammonia have been utilized as precursors. The evolutions of the thickness and the roughness of the films with the number of ALD cycles have been monitored by spectroscopic ellipsometry and atomic force microscopy, respectively. A slight difference has been observed between thermal and plasma-enhanced ALD TiN films. The chemical composition of the resulting layers for the two activation modes has been investigated by X-ray photoelectron spectroscopy. It indicates a partial oxidation of the film and it shows that the oxide content depends on the activation method and varies with the deposition temperature. The studies of both morphology and crystalline structure carried out by electron microscopy and X-ray diffraction have revealed homogeneous and polycrystalline films for the two activation processes. Electrical measurements have shown that the films grown by plasma-activation exhibit a higher conductivity. Finally, the TiN films were grown on high aspect ratio templates such as anodic aluminum oxide membranes. It demonstrates that highly-conformal TiN thin films can even be obtained by plasma-assisted process within such narrow three-dimensional nanostructures. That was unexpected.

Process-Dependent N/PBTI Characteristics of TiN Gate FinFETs

A study of the negative and positive bias temperature instability (N/PBTI) reliability of FinFETs with different TiN metal gates deposited by either atomic layer deposition (ALD) or physical vapor deposition (PVD) on HfO2 dielectrics found that the nonuniformity of the interfacial oxide layer is closely related to reliability characteristics. FinFETs with an ALD TiN gate exhibit better NBTI and PBTI lifetimes than those with a PVD TiN gate. In addition, the dependence of fin width on NBTI reliability appeared to be worse with narrower fins, whereas PBTI reliability improves.

Four Point Probe Structures With Buried and Surface Electrodes for the Electrical Characterization of Ultrathin Conducting Films

Test structures for the electrical characterization of ultrathin conductive films are presented based on electrodes on which the ultrathin film is deposited. Two different designs are discussed: a novel design with buried electrodes and a conventional design with electrodes at the surface. This paper includes test structure design and fabrication, and the electrical characterization of atomic layer deposition TiN films down to 4 nm. We demonstrate that the novel test structures provide the same results as the conventional structures, and have the advantage of broader materials choice (i.e., conductor-dielectric combination). The proposed structures can be used successfully to characterize sub-10 nm films.