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Développement de briques technologiques pour la fabrication de composants de puissance MOS sur diamant

Lya Fontaine 1
1 LAAS-ISGE - Équipe Intégration de Systèmes de Gestion de l'Énergie
LAAS - Laboratoire d'analyse et d'architecture des systèmes
Abstract : One of the major challenges of our century is related to the management and consumption of energy. The improvement of power devices is one of the keys to meeting these constraints. The majority of today's power devices are still silicon-based devices. However, the requirements of power electronics in terms of high voltages, high power densities, temperatures and higher frequencies are becoming more severe. Thus, the physical properties of other materials such as wide-bandgap semiconductors make it possible to consider the replacement of silicon for the design and fabrication of higher performance power devices. This is the case of gallium nitride, silicon carbide and diamond. This work focuses on the development and optimization of the fundamental technological steps for the realization of diamond MOS power devices. This is the goal of the ANR MOVeToDIAM project, coordinated by the LAAS-CNRS and heir to the work on diamond done in the laboratory since 2005. Diamond is a wideband semiconductor (Eg = 5.5 eV) particularly suitable for high power applications. It has high carrier mobilities (2200 cm2 / Vs for electrons and 2050 cm2 / Vs for holes), allowing the passage of high current densities, a high breaking field (Ec ~ 10 MV / cm) and a strong thermal conductivity (λ ~ 20 W.cm-1.K-1) facilitating heat dissipation and thus allowing the fabrication of devices operating at high temperatures. However, despite these promising properties, many technological barriers complicate or prevent the fabrication of diamond power devices. To remove these locks, several technological steps have been studied and optimized in our work to overcome the problems caused by the small sample sizes (2x2mm2 to 3x3mm2). The photolithography steps were developed and optimized for two types of resin (AZ4999 positive and NLOF 2035 negative) using a Spray-Coater and a laser insolation machine, thus greatly improving the minimal resolution of the patterns made on these small samples. The fabrication of two test structures called Transmission Line Method (TLM) and Circular Transmission Line Method (cTLM) to characterize ohmic contacts has also been optimized for diamond samples. If the realization of ohmic contacts on P-type diamond is mastered, the specific contact resistance must be further improved to limit its impact on the electrical performance of the devices. Moreover, according to the literature, no contact made on N-type diamond has shown ohmic behavior, which remains a major obstacle to the development of the diamond industry. The fabrication of ohmic contacts was then optimized on several P-type and N-type diamond samples. Several overdoping techniques were tested on the N-type samp! les. The contacts characterized using the TLM patterns developed show that Phosphorus implantation by PIII gives ohmic contacts, which is explained by the presence of a conductive graphite layer on the surface of the sample. Finally, MIS capabilities were fabricated. The Si3N4 dielectric was chosen for its properties and the quality of its LPCVD deposition in the laboratory. The deposited thickness was optimized and the devices were fabricated on a P-type sample and an N-type sample. The characterized capacities show a rectifying behavior and open the way towards the realization of a diamond MOSFET.
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Submitted on : Wednesday, September 30, 2020 - 10:30:03 AM
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Lya Fontaine. Développement de briques technologiques pour la fabrication de composants de puissance MOS sur diamant. Micro et nanotechnologies/Microélectronique. Université Toulouse 3 Paul Sabatier (UT3 Paul Sabatier), 2020. Français. ⟨tel-03046537v2⟩

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