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Examines the function of PVD-Titanium based thin films as commonly used materials in diffusion barrier in semiconductor industry. Presentation of the atomic layer deposition; Capabilities of the low resistivity ternary material.

Metal oxide-based resistive random access memory devices are highly attractive candidates for next-generation nonvolatile memories, but the resistive switching phenomena remain poorly understood. This article focuses on the microscopic understanding of the initial forming step, which is decisive for the switching process. The integrated resistive switching memory effect in Ti / Hf O 2 / TiWN metal insulator metal structures is studied. After forming, transmission electron microscopy investigations pointed out the presence of a funnel-shaped region, in the ON state of the cell, where slightly oxidized Ti (Ti Ox ) was present within Hf O 2 dielectric. Modeling of the measured ON state conductance of the cell with the semi-classical approximation is consistent with a conductive nanometric Ti Ox filament (or a sum of sub-nanometric Ti Ox filaments) present in the funnel-shaped region. The conductive area is likely formed by diffusion after the dielectric breakdown. [ABSTRACT FROM AUTHOR]

Metal matrix nanocomposite thin films consisting of TiF3 nanoparticles embedded in TiN matrix were synthesized with the atomic layer deposition (ALD) method. TiF4, Si2H6 (or Si3H8), and NH3-based process at 350-370 °C led to nanocomposite TiF3:TiN thin films with the embedded TiF3 nanoparticles in the size range of 2-50 nm. The films grown on quartz wafers were conductive and transparent in the visible spectral range. The resistivities of the films could be controlled by the (TiF4 + Si2H6)/NH3 pulsing ratio. Transparency of the films correlated with the resistivity of the films, namely the more transparent the films were, the higher the resistivities. About 4 cm2 area photovoltaic cells with TiF3:TiN/SiO2 (1.5-20 nm)/p-Si (1-85 Ωcm)/SiO2 (1.5-20 nm)/TiN structures resulted in 0.10-0.45 V open circuit voltage and 1-2.5 μA current flow into a 120 Ω load resistor under halogen lamp (Osram 50 W, 240 V bulb, 2800 K) illumination. The mechanism of the photovoltaic effect in these structures is not known in detail, but it is suggested that the TiF3:TiN nanocomposite functions as a partly transparent conducting electrode on the silicon wafer forming a MIS-type silicon photovoltaic cell. This new material and its derivatives may have multiple applications in current and future photonic devices. TEM images of the TiF3:TiN nanocomposite thin film. The plan view image is a dark field image showing the TiF3 crystallites as bright spots, whereas the cross sectional image is a bright field image showing the TiF3 crystallites as dark spots. [ABSTRACT FROM AUTHOR]

Atomic layer deposition (ALD) is used in applications where inorganic material layers with uniform thickness down to the nanometer range are required. For such thicknesses, the growth mode, defining how the material is arranged on the surface during the growth, is of critical importance. In this work, the growth mode of the zirconium tetrachloride/water and the trimethyl aluminum/water ALD process on hydrogen-terminated silicon was investigated by combining information on the total amount of material deposited with information on the surface fraction of the material. The total amount of material deposited was measured by Rutherford backscattering, x-ray fluorescence, and inductively coupled plasma–optical emission spectroscopy, and the surface fractions by low-energy ion scattering. Growth mode modeling was made assuming two-dimensional growth or random deposition (RD), with a “shower model” of RD recently developed for ALD. Experimental surface fractions of the ALD-grown zirconium oxide and aluminum oxide films were lower than the surface fractions calculated assuming RD, suggesting the occurrence of island growth. Island growth was confirmed with transmission electron microscopy (TEM) measurements, from which the island size and number of islands per unit surface area could also be estimated. The conclusion of island growth for the aluminum oxide deposition on hydrogen-terminated silicon contradicts earlier observations. In this work, physical aluminum oxide islands were observed in TEM after 15 ALD reaction cycles. Earlier, thicker aluminum oxide layers have been analyzed, where islands have not been observed because they have already coalesced to form a continuous film. The unreactivity of hydrogen-terminated silicon surface towards the ALD reactants, except for reactive defect areas, is proposed as the origin of island growth. Consequently, island growth can be regarded as “undesired surface-selective ALD.” [ABSTRACT FROM AUTHOR]

• A novel dry non-plasma etching process for titanium nitride (TiN) is demonstrated. • SOCl 2 etches TiN selectively over Al 2 O 3 , SiO 2 , and Si 3 N 4 from 270 °C to 370 °C. • Angstrom level thickness control can be achieved by applying etch cycles. • SOCl 2 removes TiN from non-line-of-sight features and isotropically. • Thermodynamic calculations predict formation of volatile species such as TiCl 4 , TiCl 3 , N 2 , N 2 O etc. In this work, thermal based gas-phase etching of titanium nitride (TiN) is demonstrated using thionyl chloride (SOCl 2) as a novel etchant. A single etchant is utilised in a pulsed fashion to etch TiN. This type of etching technique may also be considered as a chemical gas-phase or dry etching. The removed TiN amount was measured by various techniques like spectroscopic ellipsometry (SE), weighing balance and in some cases X-ray reflectometry (XRR). Additionally, the post-etch surfaces were analysed with X-ray photoelectron spectroscopy (XPS) and bright field transmission electron microscopy (BF-TEM). The surface roughness and morphology of before and after etching TiN films were measured using atomic force microscopy (AFM). The etch per cycle (EPC) was calculated and is plotted as a function of SOCl 2 pulse time, purge time after SOCl 2 exposure, number of etch cycles and etch temperature ( T etch ). An increase in EPC with an increase in SOCl 2 pulse time as well as etch temperature was observed. SOCl 2 is able to etch TiN starting from 270 °C with an EPC of about 0.03 Å to almost 1.2 Å at 370 °C. Arrhenius plot determined the activation energy (E a) of about 25 kcal/mol for TiN etching by SOCl 2. In addition, the etch selectivity between different substrates such as silicon dioxide (SiO 2), silicon nitride (Si 3 N 4) and aluminum oxide (Al 2 O 3) was investigated on blanket as well as 3D structures. Moreover, thermodynamic calculations were performed for various possible etch reactions. Titanium from TiN is proposed to be etched in the form of either titanium trichloride (TiCl 3) or titanium tetrachloride (TiCl 4). Nitrogen from TiN films may form volatile by-products such as diatomic nitrogen (N 2), nitrous oxide (N 2 O) and nitrogen dioxide (NO 2). [ABSTRACT FROM AUTHOR]

The properties of WN[SUBx]C[SUBy] films deposited by atomic layer deposition (ALD) using WF[SUB6], NH[SUB3], and triethyl boron as source gases were characterized as a diffusion barrier for copper metallization. It is noted that the as-deposited film shows an extremely low resistivity of about 350 μΩ cm with a film density of 15.37 g/cm[SUP3]. The film composition measured from Rutherford backscattering spectrometry shows W, C, and N of ∼ 48, 32, and 20 at. %, respectively. Transmission electron microscopy analyses show that the as-deposited film is composed of face-centered-cubic phase with a lattice parameter similar to both β-WC[SUB1-x] and β-W[SUB2]N with an equiaxed microstructure. The barrier property of this ALD-WN[SUBx]C[SUBy] film at a nominal thickness of 12 nm deposited between Cu and Si fails only after annealing at 700 °C for 30 min. [ABSTRACT FROM AUTHOR]

Structural and electrical properties of gate stack structures containing ZrO[sub 2] dielectrics were investigated. The ZrO[sub 2] films were deposited by atomic layer chemical vapor deposition (ALCVD) after different substrate preparations. The structure, composition, and interfacial characteristics of these gate stacks were examined using cross-sectional transmission electron microscopy and x-ray photoelectron spectroscopy. The ZrO[sub 2] films were polycrystalline with either a cubic or tetragonal crystal structure. An amorphous interfacial layer with a moderate dielectric constant formed between the ZrO[sub 2] layer and the substrate during ALCVD growth on chemical oxide-terminated silicon. Gate stacks with a measured equivalent oxide thickness (EOT) of 1.3 nm showed leakage values of 10[sup -5] A/cm[sup 2] at a bias of -1 V from flatband, which is significantly less than that seen with SiO[sub 2] dielectrics of similar EOT. A hysteresis of 8-10 mV was seen for ±2 V sweeps while a midgap interface state density (D[sub it]) of ∼3x10[sup 11] states/cm eV was determined from comparisons of measured and ideal capacitance curves. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]