L. Ouellet

Bio: L. Ouellet is an academic researcher. The author has contributed to research in topics: Thin film & High-κ dielectric. The author has an hindex of 7, co-authored 7 publications receiving 192 citations.

High-k titanium silicate thin films grown by reactive magnetron sputtering for complementary metal-oxide-semiconductor applications

Abstract: Titanium silicate ( TiSi x O y ) thin films have been successfully deposited by means of radio-frequency magnetron sputtering of a TiO 2 / SiO 2 composite target in a reactive gas atmosphere. The deposition of the films was investigated as a function of the [ O 2 ]/([ Ar ]+[ O 2 ]) flow ratio in the 0%–30% range. The bonding states and the dielectric properties of the sputter-deposited TiSi x O y films were systematically investigated as a function of the O 2 flow ratio. For all the O 2 flow ratios studied, Fourier-transform infrared and x-ray photoelectron spectroscopy analyses have clearly revealed the presence of Ti–O–Si type of local environments, which are the fingerprint of the titanium silicate phase. Increasing the O 2 proportion in the sputtering chamber was found to cause a significant decrease of the deposition rate and a drastic improvement in the dielectric properties of the films. TiSi x O y films exhibiting excellent dielectric properties (i.e., a dielectric constant as high as ∼20, a dissipation factor as low as 0.01, and a low leakage current density of 10 −3 A/cm 2 at 1 MV/cm) were indeed achieved under high O 2 flow ratio conditions (⩾20%). In contrast, filmsdeposited under low O 2 flow ratio conditions (⩽5%) have exhibited poor dielectric properties. The presence of oxygen vacancies in the films is invoked as a possible explanation for the observed variations of their dielectric properties with the O 2 flow ratio.

Room-Temperature Deposited Titanium Silicate Thin Films for MIM Capacitor Applications

Abstract: High-k titanium silicate (i.e., TiSiO4) thin films of various thicknesses (in the 4.5- to 160-nm range) were successfully deposited by means of a sputter deposition process at room-temperature and integrated into metal-insulator-metal (MIM) capacitors. It is shown that the TiSiO4-based capacitors can exhibit a capacitance density as high as 30 fF/mum2 while maintaining low dielectric dispersion and losses. An excellent voltage linearity was also obtained ( alpha~600 ppm/V2 at 8.2 fF/mum2) together with a high dielectric constant of 16.5 and low leakage current of about 10 nA/cm2 at 1 MV/cm. Our results thus show that TiSiO4 films constitute a very promising approach for the achievement of high performance MIM capacitors

Compositional effect on the dielectric properties of high-k titanium silicate thin films deposited by means of a cosputtering process

Abstract: We report on the successful growth of high dielectric constant (high-k) titanium silicate TixSi1−xO2 thin films of various compositions (0⩽x⩽1) at room temperature from the cosputtering of SiO2 and TiO2 targets. The developed process is shown to offer the latitude required to achieve not only a precise control of the film composition but an excellent morphology (i.e., dense films with low roughness) as well. The Fourier transform infrared and x-ray photoelectron spectroscopy characterizations have evidenced the presence of Ti–O–Si type of atomic environments, which is the fingerprint of the titanium silicate phase. The titanium silicate films are found to exhibit excellent dielectric properties with very low dielectric losses [tan(δ)<0.02] regardless of their composition. The dielectric constant of the films is found to increase with their TiO2 content from 4 (for pure SiO2 films) to 45 (for TiO2). On the other hand, increasing the TiO2 content of the films is also shown to degrade significantly their lea...

Tuning the electrical resistivity of pulsed laser deposited TiSiOx thin films from highly insulating to conductive behaviors

Abstract: We report on the successful growth of amorphous TiSiOx thin films by means of pulsed-laser ablation of a TiO2/SiO2 composite target in a high-vacuum chamber. The room-temperature resistivity of the TiSiOx films is found to decrease by more than 6 orders of magnitude (i.e., from ∼2×104 to 10−2 Ω cm) when their substrate deposition temperature (Td) is increased from 20 to 600 °C. On the other hand, by subjecting these films to a post-deposition annealing at 600 °C in oxygen atmosphere, they become highly insulating with a resistivity level as high as 2×1010 Ω cm, regardless of the Td value. The presence of conductive titanium silicide and titanium sub-oxide local phases in the as-deposited TiSiOx films, as revealed by photoelectron spectroscopy analyses, appears to be the cause of the observed tremendous change in the film resistivity. In particular, it is shown that the resistivity of the TiSiOx films is strongly correlated with their oxygen content.

Superhydrophobic Coatings with Reduced Ice Adhesion

Abstract: A brief description of how superhydrophobicity can help mitigate the ice accretion problem on power network equipment and other exposed structures by reducing ice-to-surface adhesion is presented. Basic models, namely the Wenzel and Cassie–Baxter models, accounting for the contact angle of water on solid surfaces relating to the influence of surface roughness on hydrophobicity are discussed. The results on superhydrophobic aluminum surfaces, superhydrophobic nanostructured silver thin films, superhydrophobic nanostructured zinc oxide as well as superhydrophobic nanofibres are also discussed. Some of the superhydrophobic surfaces were tested for ice adhesion and a reduced ice adhesion was obtained.

Fluorine Based Superhydrophobic Coatings

Abstract: Superhydrophobic coatings, inspired by nature, are an emerging technology. These water repellent coatings can be used as solutions for corrosion, biofouling and even water and air drag reduction applications. In this work, synthesis of monodispersive silica nanoparticles of ~120 nm diameter has been realized via Stober process and further functionalized using fluoroalkylsilane (FAS-17) molecules to incorporate the fluorinated groups with the silica nanoparticles in an ethanolic solution. The synthesized fluorinated silica nanoparticles have been spin coated on flat aluminum alloy, silicon and glass substrates. Functionalization of silica nanoparticles with fluorinated groups has been confirmed by Fourier Transform Infrared spectroscopy (FTIR) by showing the presence of C-F and Si-O-Si bonds. The water contact angles and surface roughness increase with the number of spin-coated thin films layers. The critical size of ~119 nm renders aluminum surface superhydrophobic with three layers of coating using as-prepared nanoparticle suspended solution. On the other hand, seven layers are required for a 50 vol.% diluted solution to achieve superhydrophobicity. In both the cases, water contact angles were more than 150°, contact angle hysteresis was less than 2° having a critical roughness value of ~0.700 µm. The fluorinated silica nanoparticle coated surfaces are also transparent and can be used as paint additives to obtain transparent coatings.

Synthesis of Monodisperse Fluorinated Silica Nanoparticles and Their Superhydrophobic Thin Films

Abstract: Monodispersive silica nanoparticles have been synthesized via the Stober process and further functionalized by adding fluorinated groups using fluoroalkylsilane in an ethanolic solution. In this process, six different sizes of fluorinated silica nanoparticles of varying diameter from 40 to 300 nm are prepared and used to deposit thin films on aluminum alloy surfaces using spin coating processes. The functionalization of silica nanoparticles by fluorinated group has been confirmed by the presence C–F bonds along with Si–O–Si bonds in the thin films as analyzed by Fourier transform infrared spectroscopy (FTIR). The surface roughnesses as well as the water contact angles of the fluorinated silica nanoparticle containing thin films are found to be increased with the increase of the diameter of the synthesized fluorinated silica nanoparticles. The thin films prepared using the fluorinated silica nanoparticles having a critical size of 119 ± 12 nm provide a surface roughness of ∼0.697 μm rendering the surfaces ...

Atomic layer deposited titanium silicon oxide films

Abstract: A dielectric layer containing an atomic layer deposited titanium silicon oxide film disposed in an integrated circuit and a method of fabricating such a dielectric layer provide a dielectric layer for use in a variety of electronic devices. Embodiments include forming titanium silicates and/or mixtures of titanium oxide and silicon oxides as dielectric layers in devices in an integrated circuit. In an embodiment, a titanium silicon oxide film is formed by depositing titanium oxide by atomic layer deposition and silicon oxide by atomic layer deposition onto a substrate surface. Embodiments include structures for capacitors, transistors, memory devices, and electronic systems with dielectric layers containing an atomic layer deposited titanium silicon oxide film, and methods for forming such structures.

High density metal-insulator-metal capacitor based on ZrO2∕Al2O3∕ZrO2 laminate dielectric

Abstract: The metal-insulator-metal (MIM) capacitor for analog and rf applications has been developed with ZrO2∕Al2O3∕ZrO2 laminate as the dielectric. The high capacitance density of 21.54fF∕μm2 can be achieved due to the tetragonal ZrO2 which makes the higher dielectric constant of 38.7. This MIM capacitor also demonstrates the quadratic voltage coefficient of 2443ppm∕V2 and the good leakage current of 2.11×10−6A∕cm2 at 2V which is ascribed to the inserted Al2O3. Since the Schottky emission is suggested as the major dielectric conduction mechanism, a further reduced quadratic voltage coefficient and leakage characteristic can be realized by using a high work-function electrode. The combination of the promising electrical properties and the desirable process integration renders this structure highly suitable for advanced MIM capacitors.