Contribution aux analyses de fiabilité des transistors HEMTs GaN ; exploitation conjointe du modèle physique TCAD et des stress dynamiques HF pour l'analyse des mécanismes de dégradation

Damien Saugnon 1
1 LAAS-MOST - Équipe Microondes et Opto-microondes pour Systèmes de Télécommunications
LAAS - Laboratoire d'analyse et d'architecture des systèmes [Toulouse]
Abstract : In the race for technological developments, a revolution has been induced by the appearance of Nitride technologies for two decades. These high-bandwidth technologies offer a unique combination of improved power performance, integration and energy balance for high-frequency applications (Ka-band L-band in industrial production). These technologies strongly mobilize the academic and industrial circles to propose improvements in particular on the aspects of reliability. The large efforts made by industrial and academic consortia have made it possible to better identify, understand and control certain major aspects limiting the reliability of components, and thus promote the qualification of certain sectors. However, the correlation and the detailed physical analysis of degradation mechanisms still raises many questions, and it is essential to strengthen these studies by a multi-tool analysis approach. We propose in this work of thesis a strategy of analysis according to two major aspects. The first concerns the implementation of a stress bench that allows monitoring of many static and dynamic electrical markers, without changing the connection conditions of the devices under test. The second is to implement a TCAD physical model most representative of the technology studied in order to calibrate the component at different periods of stress. The first chapter is devoted to the presentation of the main reliability tests of GaN HEMTs, and the electrical and / or structural defects identified in the literature; this includes so-called non-invasive techniques (ie, respecting the functional integrity of the component under test), and destructive techniques (ie, not allowing for the resumption of measured). The second chapter presents the high frequency and thermal stress bench developed for the purposes of this study; the addition of a vector network analyzer switching on the four test channels allows to have dynamic frequency data, in order to interpret the variations of the electrical model small-signal modules under test at different periods of stress. Aging results of 4,2 GHz HEMTs GaN components, performed at ambient temperature and for different compression points of the output power, are interpreted, leading to original observations on the identified degradation mechanism. The third chapter deals with TCAD physical simulation of HEMT GaN transistor; this model is calibrated on an industrial sector (on which we have many data), but can be adapted according to technological developments of other sectors. Our model has been developed in order to give a first-order account of the impact of fixed charges (depending on their location) on the instabilities of threshold voltages and carrier density in the channel, observed after HTOL constraints. This model makes it possible to distinguish effects specific to the channel from those induced by the grid control. In the last chapter, we use the GaN technology developed at the Université de Sherbrooke to design a prototype of a MMIC and hybrid 4.2GHz mono-stage amplifier.
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Damien Saugnon. Contribution aux analyses de fiabilité des transistors HEMTs GaN ; exploitation conjointe du modèle physique TCAD et des stress dynamiques HF pour l'analyse des mécanismes de dégradation. Micro et nanotechnologies/Microélectronique. Université Toulouse 3 Paul Sabatier (UT3 Paul Sabatier), 2018. Français. ⟨tel-01922315⟩



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