Micro-Fabrication of Planar Inductors for High Frequency DC-DC Power Converters

International audienc

Modeling, Fabrication, and Characterization of Planar Inductors on YIG Substrates

International audienceThis paper presents the design, fabrication, and characterization of micro planar inductors on a microwave magnetic material (YIG). Planar spiral inductors were designed for monolithic DC-DC converters in System-In-Package with 100 MHz switching frequency (1 W, Vin= 3.6 V, Vout= 1 V). A microwave magnetic substrate (YIG) serves as mechanical support, and also presents a double purpose by increasing inductance value and reducing electromagnetic interferences (EMI). This last point is critical to improve the behavior of a switching mode power supply (SMPS). In order to obtain an optimal design for the inductor, geometrical parameters were studied using Flux2D simulator and an optimized 30 to 40 nH spiral inductor with expected 25 mΩ RDC, 3 mm2 footprint area was designed. Subsequently, samples have been fabricated by electroplating technique, and tested using a vector network analyzer in the 10 MHz to 100 MHz frequency range. Results were then compared to the predicted response of simulated equivalent model

Croissance hétéroépitaxiale du SiC-3C sur substrats SiC hexagonaux; Analyses par faisceaux d'ions accélérés des impuretés incorporées

Using silicon as substrate for growing 3C-SiC monocrystalline material generates too many defects in the layers due to lattice and thermal expansion mismatch. Though these difficulties are avoided byusing hexagonal SiC substrates, the random formation of 60° rotated domains in the 3C layers generate a high density of twins.The use of vapour phase epitaxy for the growth did not allow reducing significantly the twin densitydespite the optimization of the in situ surface preparation of the seeds. On the other hand, these defects were eliminated by using Vapor-Liquid-Solid mechanism which consists in feeding a Si-Ge melt withpropane.The characterization of these twin-free layers showed excellent crystalline quality. Some of theimpurities incorporated during growth (Ge, Al, B, Sn) were successfully analysed using acceleratedion beam techniques though the detection and quantification of these elements inside SiC thin filmsare challenging.L'utilisation de germes Si pour l'épitaxie du SiC-3C génère de nombreux défauts dans les couches enraison du désaccord de maille et de la dilatation thermique. Le SiC-3C peut aussi être déposé sursubstrats SiC-α(0001) en s'affranchissant des problèmes rencontré sur substrat Si. La difficulté decontrôler la germination initiale génère cependant des macles qui sont difficiles à éviter ou éliminerensuite.L'utilisation de l'épitaxie en phase vapeur comme technique de croissance n'a pas permis des'affranchir de ces macles malgré l'optimisation de la préparation de surface des germes SiC- α. En revanche, des couches de SiC-3C exemptes de macle ont été obtenues en utilisant une technique decroissance originale, les mécanismes vapeur-liquid-solide, qui consiste à alimenter un bain Si-Ge avecdu propane.La caractérisation des couches ainsi élaborées a montré une excellente qualité cristalline avec toutefois une incorporation non négligeable d'impuretés. Les éléments Al, Ge, B et Sn ont été dosés avec succès en utilisant des analyses par faisceaux d'ions accélérés, techniques peu conventionnelles pour SiC et présentant un challenge analytique

Full densification of molybdenum powders and multilayer materials obtained by Spark Plasma Sintering

International audienceMolybdenum powders with two different particle sizes were sintered using the Spark Plasma Sintering (SPS) process. A near to 1 density are obtained in a few minutes. A Molybdenum/Aluminum Nitride multilayer was obtained while sintering in one step, using the SPS process

Growth of Nanocrystalline Translucent h-BN Films Deposited by CVD at High Temperature on SiC Substrates

International audienc

Deposition of nanocrystalline translucent h-BN films by chemical vapor deposition at high temperature

International audienc

Full densification of Molybdenum powders using Spark Plasma Sintering

International audiencePure molybdenum powder was sintered using Spark Plasma Sintering under various temperatures, and holding times, under a pressure of 77 MPa and a heating rate at 700°C/min. After sintering, a carbide layer was observed at the surface. The carbide layer thickness, the relative density of the sample as well as the microhardness and the grain size of Mo were measured. The carbide thickness depends on time and temperature and it was found that the carbide layer grows in a parabolic manner, with the activation energy of carbon diffusion in Mo being equal to 34 Kcal/mol. The densification of Mo is controlled mainly by the sintering temperature and the holding time. The molybdenum powder was successfully consolidated by SPS in short times. A relative density of 100% is achieved at a sintering temperature of 1850°C and a holding time of 30 minutes. It was shown that the hardness decreases slightly with temperature and time. It should be related to the increase in grain size with the sintering temperature and time

On the characterization of boron in BGaAs nano-films using IBA technique

International audienceIn this work, the capability of the proton Induced γ-ray Emission (PIGE) technique to monitor a rapid, nondestructive and quantification of Boron in ultra-thin films of BxGa1-xAs deposited on GaAs substrate using MOCVD is discussed. In order to improve the sensitivity for B detection, a systematic study was undertaken using proton induced beam at three different energies (from 1.7, 2.4 and 3 MeV) with different tilting angles (0, 60° and 80°). Best conditions were found to be at 1.7 MeV and at 80° for proton energy and tilting angle within ten minutes of acquisition time