Marie-Christine Hugon

Effects of post-deposition annealing in O2 on the electrical characteristics of LaAlO3 films on Si

LaAlO3 films were deposited on p-type Si(100) by sputtering from a LaAlO3 target. C×V characteristics were determined in nonannealed and O2-annealed capacitors having LaAlO3 films as dielectric and RuO2 as top electrode. Thermal annealing in O2 atmosphere reduced flat band voltage to acceptable values for advanced Si-based devices. O16–O18 isotopic substitution was characterized by Rutherford backscattering spectrometry and nuclear resonant reaction profiling. Chemical analysis of the films was accomplished by x-ray photoelectron spectroscopy. The electrical improvements observed after thermal annealing in O2 were attributed to the incorporation of oxygen from the gas phase, possibly healing oxygen vacancies in the films and providing mobile oxygen to the interface.

New type of plasma reactor for thin film deposition: magnetron plasma process assisted by microwaves to ionise sputtered vapour

Abstract A new type of plasma reactor for thin film deposition has been designed: a magnetron-sputtering device assisted by microwave applicators to ionise the sputtered vapour of the magnetron. Ionizing the vapour has several advantages: improvement of the film quality, deposition on substrates with complex shapes, enhancement and control of the reactivity. The reactor consists of a planar rectangular magnetron cathode (22 cm×9 cm) and of two coaxial-type microwave applicators located perpendicularly to the substrate–magnetron axis, on both sides of the sputtered vapour flow. This reactor can operate on a wide pressure range: from 0.2 to 60 Pa. Several in-situ diagnostics have been performed to characterise the process in argon gas with chromium and titanium targets. Electron density of the order of 10 11 –10 12 cm −3 and electron temperature of 1.5–2 eV were measured in the microwave plasma by a cylindrical Langmuir probe; emission of metallic ions (Cr + , Ti + ) was clearly identified when the microwave plasma is turned on; concentration of Cr or Ti atoms was measured by absorption spectroscopy, a decrease of this concentration is observed when the microwave power is increased. Characterisation of thin titanium films was performed ex-situ by Rutherford backscattering spectroscopy (RBS) for Ti content and nuclear reaction analysis (NRA) for oxygen contamination. Film density was deduced from RBS and NRA measurements and X-ray reflectometry. Oxygen contamination in the film is clearly decreased when microwave plasma is turned on and with a bias applied to the substrate.

Electrical characteristics and interface structure of HfAlO∕SiON∕Si(001) stacks

The electrical characteristics of RuO2∕HfAlO∕SiON∕Si(001) capacitors prepared by thermal nitridation of the Si substrate previously to HfAlO ultrathin film deposition were determined. A dielectric constant of 19 and a gate current density of 67mA∕cm2 for an equivalent oxide thickness of 1.1nm have been determined, whereas non-nitrided capacitors gave substantially lower dielectric constant and higher gate current density. The structure and integrity of the stacks after thermal annealing were accessed by means of spectroscopic ellipsometry and x-ray reflectometry, indicating that thermal N incorporation into the gate dielectric stacks forms an effective diffusion barrier, leading to a smoother, SiO2-like interface. The HfAlO films grown on nitrided substrates were seen also to have lower porosity, percentage of voids, and density of oxygen vacancies.

Device Quality SiO2 Deposited by Distributed Electron Cyclotron Resonance Plasma Enhanced Chemical Vapor Deposition without Substrate Heating

The deposition of high electrical quality SiO2 films on Si wafers has been achieved without substrate heating, (T<~100°C), using distributed electron cyclotron resonance (DECR) microwave plasmas. We have studied the effects of the reactant gas mixture composition (O2/SiH4) on the dielectric behavior of DECR SiO2. The electrical performances of both Si-SiO2 interfaces and SiO2 films in metal-oxide-semiconductor (MOS) structures were assessed by several characterization methods including critical field (Ec) evaluation, fixed charge densities (Qox) and interface traps densities (Dit) determinations. We report typical values of Ec around 6 MVcm-1, and Qox and Dit densities around 2×1010 cm-2 and 3×1010 cm-2eV-1 respectively. Thin film SOI-MOSFETs have also been fabricated to prove the DECR oxide quality.

High density plasma deposition of device quality silicon nitride. II. Effects of thickness on the electrical properties

Dielectric behavior of SiNx films, fabricated by microwave electron cyclotron resonance discharge, has been studied as a function of film thickness on the basis of the current–voltage and the capacitance–voltage characteristics. In the thickness range (20 nm 20 nm). Finally, the spatial profile of fixed charges reveals that SiNx/Si interface has a much greater concentration of defects than the bulk film.

Low temperature deposition of SiNx:H using SiH4–N2 or SiH4–NH3 distributed electron cyclotron resonance microwave plasma

Silicon nitride films were deposited at floating temperature using distributed electron cyclotron resonance plasma enhanced chemical vapor deposition (DECR-PECVD) on Si and InP substrates. The deposition parameters studied included the nature of gases (SiH4–N2 or SiH4–NH3) and the gas phase composition (SiH4/N2 or SiH4/NH3). The experimental results establish that to obtain device quality Si3N4, it is desirable to use N2 instead of NH3 and a high diluted SiH4 gas phase. These process parameters yield to a high resistivity (1016 Ω cm) and a high critical field (4.5 MV/cm). These properties confirm that the DECR technique is well suited for processing III–V compound semiconductors. NH3 does not induce such promising characteristics in terms of electrical properties but silicon nitride deposited with this gas is particularly interesting for applications where no stress is required.

Comparison of the physical and electrical properties of electron cyclotron resonance and distributed electron cyclotron resonance SiO2

A comparison was made of thin films of silicon dioxide deposited, at floating temperatures, using electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR PECVD) and distributed electron cyclotron resonance plasma enhanced chemical vapor deposition (DECR PECVD). The refractive index, composition, and chemical bonding of the plasma oxides were determined by null and spectroscopic ellipsometry, nuclear reaction analysis, and Fourier transform infrared spectroscopy and were compared with thermal oxides. The damaged layer at the Si/SiO2 interface resulting from ECR and DECR techniques was evaluated by spectroscopic ellipsometry. Finally, high frequency and quasi‐static capacitance voltage characteristics and ramped current voltage measurements were performed to determine the electrical properties of the ECR and DECR deposited silicon oxide. Device quality SiO2 thin films have been prepared using both deposition techniques: low interface state density [5×1010 eV−1 cm−2 (ECR) or 2.5×1010 eV−1...

Comparison of damage and Si oxidation kinetics resulting from electron cyclotron resonance and distributed electron cyclotron resonance plasma processing

Interface damage and oxidation behavior are compared for electron cyclotron resonance plasma oxidation of silicon for two different plasma system configurations: a conventional system where the plasma is generated and extracted normal to the Si wafer surface, and another system where the plasma is made uniform by developing the magnetic field parallel to the substrate using permanent magnets outside the chamber and antennas inside, viz. distributed electron cyclotron resonance (DECR) plasma. Samples were compared using spectroscopic ellipsometry, nuclear reaction analysis, and transmission electron microscopy. Less damage was observed in the DECR plasma configuration, but otherwise the systems were comparable.

EPITAXIAL GROWTH OF (PB, LA)TIO3 THIN FILMS ON (0001) AL2O3 AND (001)SRTIO3 SUBSTRATES BY RF MAGNETRON SPUTTERING

Abstract Ferroelectric lead lathanum titanate (PLT) thin films were grown by rf magnetron sputtering on (0001) A12O3 and (001) SrTiO3 substrates, from a ceramic Pb0.9La0.1TiO3 target, in a reactive Ar/O2, atmosphere. The surface morphology was examined by atomic force microscopy (AFM); rms roughness of 2 to 4 nm was achieved on these films. Thin film interfaces were characterized by grazing X-ray reflectometry : they were found to be relatively smooth, and no interdiffusion layer was found between the film and the substrate. The structural properties of the films were investigated by X-ray diffraction (XRD). Perovskite single phase has been achieved with a temperature of 650°C. Pole figures and asymmetric scans show the epitaxial nature of the films.