Plasma Immersion Ion Implantation (PIII) is a promising alternative to beam line implantation to produce a single layer of nanocrystals (NCs) in the gate insulator of metal-oxide semiconductor devices. We report herein the fabrication of two-dimensional Si-NCs arrays in thin SiO2 films using PIII and rapid thermal annealing. The effect of plasma and implantation conditions on the structural properties of the NC layers is examined by transmission electron microscopy. A fine tuning of the NCs characteristics is possible by optimizing the oxide thickness, implantation energy, and dose. Electrical characterization revealed that the PIII-produced-Si NC structures are appealing for nonvolatile memories. (C) 2013 AIP Publishing LLC.

Germanium nanocrystals (Ge-NCs) have been obtained by low energy ion beam synthesis in a SiNx/HfO2 stack layer. The effect of the Ge implanted dose variations on structural characteristics (size, position, chemical bonding) of Ge-NCs have been investigated by Transmission Electron Microscopy and Raman spectroscopy. Our results show that several processes (damage, diffusion, oxidation …) that depend on the Ge implanted dose, take place during the synthesis and complicate the expected behavior of the ion beam synthesized system. However, significant memory windows with good retention properties have been observed in these stack structures, indicating their feasibility for low operating voltage, non-volatile memory devices.

Fully high-k based non-volatile memory structures were fabricated by RF magnetron sputtering technique. The pure HfO2 and HfSiO materials were used as tunnel and/or control layers, whereas HfGeO ones were used as a charge storage node. The capacitance-voltage measurements of HfO2/HfGeO/HfO2 and HfSiO/HfGeO/HfSiO stacks were performed to study the charge trapping characteristics of these structures. The memory effect was observed in both types of MIS capacitors and the optimal annealing treatment was found to be at 610°C for 15 minutes. A memory window of ~7 V at a sweeping voltage of ± 14 V has been achieved, indicating the potential use of these stack structures for non-volatile memory devices.

Non-volatile memory structures with embedded silicon nanoclusters were fabricated by RF magnetron sputtering approach. The capacitance-voltage characteristics of classical SiO2/Si-ncs-SiO2/SiO2 and HfO2/Si-ncs-SiO2/SiO2 structures have been compared. The specific deposition conditions and annealing treatment allowed a large memory window of about 6.8 V at a sweeping voltage of ± 6 V to be achieved. It was observed that the similar memory capacitance can be obtained for classical SiO2/Si-ncs-SiO2/SiO2 structures using multilayer charge storage node. The analysis of microstructural properties of the samples revealed that an annealing at 1000-1100°C results in the formation of crystallized silicon clusters, while the crystallization of HfO2 occurred with a tetragonal phase. It was also revealed that an annealing treatment at 950°C, at which amorphous Si clusters are formed, allowed a highest memory window to be obtained. This result indicates the benefit of low thermal budget treatment for low operating voltage non-volatile memory devices.

Indium oxide conducting films were deposited on p-type Si (100) substrates at various temperatures by a liquid-delivery metal organic chemical vapor deposition technique using indium (III) tris(2,2,6,6-tetramethyl-3,5-heptanedionato) (dpm)(3) precursors. The structural, morphological, and chemical bonding features of these films were studied by x-ray diffraction, scanning electron microscopy, and x-ray photoelectron spectroscopy. The effect of substrate temperature on the electrical and structural properties has been investigated to obtain a high mobility and highly conducting In(2)O(3) film. All deposited films within the temperature range of 200-400 degrees C have a [111] preferred orientation and exhibit an increase of grain size from 21 to 33 nm with increasing deposition temperature. In this range of deposition temperature, there is no metallic indium phase in deposited films. It was observed that the electrical properties of the films are closely related to the microstructure of the films. Hall mobility and electrical resistivity values of the films are comparable to most of the presently investigated transparent conducting oxide films. (C) 2008 American Vacuum Society.

The effects of post-deposition annealing process on the material and electrical properties of radio frequency (RF) reactive magnetron sputter-deposited Bi2Mg2/3Nb4/3O7 (BMN) dielectric films integrated with silicon were investigated. All post-deposition annealed samples show the presence of a silicate-type amorphous interfacial layer. The films show smooth, continuous, crack-free surfaces and preserve an amorphous phase up to an annealing temperature of 700 degrees C. The samples subjected to rapid thermal annealing in O-2 ambient and subsequently in N-2 ambient exhibit enhanced electrical characteristics, such as low values of capacitance equivalent thickness, interface state density, trap oxide charge density, reduced hysteresis and frequency dispersion, low leakage current, together with high electric field breakdown. These values are comparable to those of some of the most widely investigated high-k gate dielectrics.

Zr x Ti 1 − x O 4 (x=0.66) films were deposited on p-type Si (100) substrate using liquid-delivery metal organic chemical vapor deposition using Zr(O–C3H7)2{(C11H19O2)2} and Ti(O–C3H7)2{(C11H19O2)2} precursors. Postdeposition rapid thermal annealing was performed in N2 ambient to improve the electrical characteristics of the films. The postdeposition annealed samples show excellent electrical characteristics, such as low values of effective oxide charge density, flatband voltage, hysteresis, oxide trap charge density, and interface state density. No metal silicides were found in the films. A minimum leakage current density of the order of ∼10−5A∕cm2 at a bias voltage of −1V has been obtained even after annealing at 800°C.

Bi 2 Mg 2 ∕ 3 Nb 4 ∕ 3 O 7 pyrochlore films were deposited on p-type Si (100) substrates using radio frequency reactive magnetron sputtering technique. Rapid thermal annealing (RTA) in O2 ambient followed by RTA in N2 ambient was carried out. The structural, morphological, and chemical bonding features of these films were studied by x-ray diffraction, scanning electron microscopy, atomic force microscopy, and x-ray photoelectron spectroscopy. All the films exhibit smooth, homogeneous, continuous, crack free, and dense films surfaces with root-mean-square roughness values in the range of 1.91−4.16 Å. The films show high crystallization temperature at about 900 °C. High temperature annealing gives rise to more oxygen incorporation in the films with probable formation of silicate type bonding at the interface. Effective oxide charge density, flatband voltage, hysteresis, oxide trap charge density, and interface state density values are comparable to those of some of the most widely investigated high-k gate dielectrics. The values decrease with increasing annealing temperature. A minimum leakage current density of the order of ∼10−6 A∕cm2 at a bias voltage of −1 V has been obtained even after annealing at 800 °C. All the annealed films show high breakdown field values of more than 5 MV/cm.

Interaction of HfxTayN metal gate with SiO2 and HfOxNy gate dielectrics has been extensively studied. Metal-oxide-semiconductor (MOS) device formed with SiO2 gate dielectric and HfxTayN metal gate shows satisfactory thermal stability. Time-of-flight secondary ion mass spectroscopy (TOF-SIMS) analysis results show that the diffusion depths of Hf and Ta are less significant in SiO2 gate dielectric than that in HfOxNy. Compared to HfOxNy gate dielectric, SiO2 shows better electrical properties, such as leakage current, hysteresis, interface trap density and stress-induced flat-band voltage shift. With an increase in post metallization annealing (PMA) temperature, the electrical characteristics of the MOS device with SiO2 gate dielectric remain almost unchanged, indicating its superior thermal and electrical stability.

Compatibility and thermal stability of the metal-oxide-semiconductor (MOS) device with HfOxNy gate dielectric and HfxTayN metal gate electrode were investigated. MOS device formed by HfxTayN metal gate and HfOxNy gate dielectric shows excellent thermal stability. Compared to the TaN metal gate, HfxTayN metal gate shows an enhancement in thermal stability and electrical characteristics, such as equivalent oxide thickness (EOT), hysteresis, interface trap density, stress-induced leakage current and stress-induced flatband voltage shift. With an increase in post metallization annealing (PMA) temperature, the electrical characteristics remain almost unchanged, which, in turn, demonstrate the excellent thermal stability and electrical reliabilities of the MOS device with HfOxNy gate dielectric and HfxTayN metal gate.

Low temperature thermal oxidation of mercury-sensitized photo-CVD deposited silicon-rich silicon nitride films has been carried out to obtain high quality silicon oxynitride films with less incorporated hydrogen. The absence of SiH and NH stretching mode indicates that the incorporated hydrogen in these bonding forms is a few atomic percent, below the detection level of Fourier transform infrared spectroscopy (FTIR). X-ray photoelectron (XPS) studies suggest that oxygen is mainly incorporated in the film in the form of N(SiO)x. No significant change in the relative contributions from the Si3N4 network to the overall N1s peak takes place as a result of oxidation, but there is a decrease in the unreacted silicon from 15.3% to 5.5%. The interface electronic state densities, flat band voltage, fixed insulating charges and leakage current are reduced after oxidation, indicating an improvement of the electrical properties of the oxidized film.

Silicon nitride films have been deposited on p-type Si (100) by mercury-sensitized photo-chemical vapor deposition (photo-CVD) method varying deposition pressure and substrate temperature. Energy dispersive X-ray fluorescence spectra of the samples show that the incorporation of mercury in the films, if any, is below 20 ppm. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy studies show the incorporation of oxygen and hydrogen in all the films, which is a function of the deposition parameters. Higher substrate temperature favors the formation of SiH bonds and reverse is the case for the formation of SiNH bonds. The sample deposited at low temperature (170 °C) shows the presence of less unreacted silicon (4%) in comparison to the sample (12.5% unreacted silicon) deposited at higher deposition temperature (250 °C), but the variation of pressure shows no significant change in terms of the unreacted silicon. The incorporated hydrogen and oxygen passivate surface defects thereby influencing interface electronic state densities (Dit) and fixed insulating charges (Qss).

Silicon oxide–silicon nitride (ON) stack layers have been formed by mercury sensitized photochemical vapour deposition (photo-CVD) of silicon nitride layers over thermally grown and photo-CVD deposited silicon oxide layers on p-type Si (100) substrates. The properties of these two groups of samples were studied using Fourier transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS) and capacitance–voltage measurements. Photo-CVD deposited nitrogen-rich stoichiometric silicon nitrides over thermally grown oxides give less electronic state density with an increased Si–N bond concentration, and on the other hand photo-CVD deposited oxide–nitride stacks give less fixed oxide charges. The absence of Si–H bonds in nitrides indicates that all nitrides are hydrogenated. Oxygen incorporation in the nitride layer was studied from FTIR and XPS measurements, which in turn affects the properties of these stack layers.

Silicon nitride films were deposited by mercury-sensitized photochemical vapor deposition utilizing a gaseous mixture of Si2H6 (2% in Ar) and NH3 under 253.7 nm ultraviolet light irradiation. Non-stoichiometric silicon-rich and nitrogen-rich samples were deposited by varying gas flow ratio. High partial pressure of disilane results in the formation of clusters, with the incorporation of hydrogen in the form of SiH and NH stretching modes below the detection level of Fourier transform infrared spectroscopy. In the nitrogen-rich sample the bonded hydrogen concentration is 0.56×1018 cm−2. After annealing the samples at 350 °C for 3 h in a pressure of 50 mTorr, the interface electronic state density decreases for silicon-rich sample and increases for nitrogen-rich sample.

We have examined the influence of bonded hydrogen on the losses in silicon oxynitride (SiON) planar optical waveguides on silicon substrates having a silicon dioxide buffer layer. In the SiON layer grown by plasma enhanced chemical vapour deposition, hydrogen was mainly bonded to silicon as evidenced by strong absorption at 2160 cm-1 . The concentration of bonded hydrogen was reduced from 1.2 × 1022 cm-3 to 5 × 1021 cm-3 as the substrate temperature was raised from 100 to 300 °C. The corresponding change in the loss was from 1.5 to 1.2 dB cm-1 at 632.8 nm.