Elektroniniu formatu saugomos informacijos apimtys ir svarba vis didėja. Pamažu į elektroninę erdvę perkeliama vis daugiau dokumentų ir viešųjų paslaugų. Anksčiau dokumentų ir duomenų originalumą bei teisingumą patvirtindavo dokumento originalas saugomas archyve, ant kurio visuomet turėjo būti atsakingų asmenų parašai. Siekiant užtikrinti elektroninių dokumentų autentiškumą sukurta elektroninio parašo technologija. Elektroninis parašas – efektyvus būdas užtikrinti dokumento autentiškumą, t.y. patikima ir pasitikėjimą kelianti technologija. Ką daryti tuo atveju, kai reikia didinti pasitikėjimą duomenimis, kurie gaunami iš dokumento ir išsaugomi kaip tam tikros sistemos duomenys? Daliai tokių duomenų būdinga savybė keistis, pvz. moters pavardė po santuokos, kiti duomenys atvirkščiai – turi likti nepasikeitę visą savo gyvavimo periodą, pvz. eksperimentų rezultatai, finansinės apskaitos duomenys. Pirmuoju atveju dažnai tikslinga žinoti kas, kada ir kaip keitė duomenys. Antruoju – tikslinga įsitikinti, kad duomenys tikrai nebuvo pakeisti. Šio darbo metu nagrinėjama būtent pastaroji problema, t.y., kaip padidinti pasitikėjimą duomenimis, kurie turi išlikti autentiški. Darbo metu analizuojama sukurta sistema, kuria siekiama užtikrinti duomenų, o ne dokumentų autentiškumą, panaudojant elektroninį parašą. Taip pat atliekamas eksperimentas palyginantis jau egzistuojančio sprendimo ir pasiūlytos sistemos charakteristikas. / The importance and volume of information stored in electronic form grows in days rather than years. More and more documents and public services are gradually being moved to electronic space. Some time before, document and data originality were endorsed by the original documents which were stored in archives. To ensure electronic documents originality the electronic signature technology was created. Electronic signature is an effective way to ensure the authenticity of the document, i.e. this is a reliable and raising confidence technology. What should we do in case of a need to increase confidence in the data, which are derived from the document and saved as a third party system data? One kind of the data have tendency to change, for example woman's surname after marriage. The other kind has opposite feature – it remains unchanged throughout the period of its existence, for example results of experiments, the accounting data. In the first case is often useful to know who, when and how changed the data. The second case is a bit different – it is crucial to make sure that the data did not change at all. This work is a research on the latter issue, i.e. how to increase confidence in the data, which must remain authentic. A system was developed during the research. It uses electronic signature to prove data authenticity rather than document. We also conducted an experiment comparing the existing and the proposed system performance.

Le sujet de cette thèse est l’analyse de la fiabilité des transistors bipolaires à hétérojonction SiGe:C et descircuits intégrés associés. Dans ce but, un modèle compact prenant en compte l’évolution des caractéristiquesdes transistors SiGe:C a été développé. Ce modèle intègre les lois de vieillissement des mécanismes dedéfaillance des transistors identifiés lors des tests de vieillissement. Grâce aux simulations physiques TCADcomplétées par une analyse du bruit basses fréquences, deux mécanismes de dégradations ont été localisés. Eneffet, selon les conditions de polarisation, des porteurs chauds se retrouvent injectés aux interfaces dutransistor. Ces porteurs chauds ont suffisamment d’énergie pour dégrader l’interface en augmentantprogressivement leurs densités de pièges. L’une des deux interfaces dégradées se situe au niveau del’’’espaceur’’ émetteur-base dont l’augmentation de la densité de piège dépend des porteurs chauds créés parionisation par impact. L’autre interface dégradée se situe entre le silicium et le STI dont l’augmentation dedensité de pièges dépend des porteurs chauds générés par ionisation par impact et/ou par génération Auger.En se basant sur ces résultats, une loi de vieillissement a été incorporée dans le modèle compact HICUM. Enutilisant ce modèle, l’étude de l’impact des mécanismes de défaillance sur un circuit amplificateur faible bruit aété menée. Cette étude a montré que le modèle compact intégrant les lois de vieillissement offre la possibilitéd’étudier la fiabilité d’un circuit complexe en utilisant les outils de conception standard permettant ainsi dediminuer le temps de conception global. / The SiGe:C HBT reliability is an important issue in present and future practical applications. To reduce the designtime and increase the robustness of circuit applications, a compact model taking into account aging mechanismactivation has been developed in this thesis. After an aging test campaign and physical TCAD simulations, onemain damage mechanism has been identified. Depending on the bias conditions, hot carriers can be generatedby impact ionization in the base-collector junction and injected into the interfaces of the device where trapdensity can be created, leading to device degradation. This degradation mechanism impacting the EB/spacerinterface has been implemented in the HICUM compact model. This compact model has been used to performreliability studies of a LNA circuit. The CPU simulation time is not impacted by the activation of the degradationcompact model with an increase in computation time lower than 1%. This compact model allows performing areliability analysis with conventional circuit simulators and can be used to assist the design of more robustcircuits, which could help in reducing the design time cycle. / L’affidabilità dei transistori a eterogiunzione SiGe:C è un aspetto molto importante nella progettazione circuitale,sia per le tecnologie attuali che per quelle in fase di sviluppo. In questo lavoro di tesi è stato sviluppato un modellocompatto in grado di descrivere i principali meccanismi di degrado, in modo da contribuire alla progettazione dicircuiti relativamente più robusti rispetto a tali fenomeni, ciò che potrebbe favorire una riduzione dei tempi diprogetto. A seguito di una campagna sperimentale e di un’analisi con tecniche TCAD, è stato identificato unmeccanismo principale di degrado. In particolari condizioni di polarizzazione, i portatori ad elevata energiagenerati per ionizzazione a impatto nella regione di carica spaziale, possono raggiungere alcune interfacce deldispositivo e ivi provocare la formazione di trappole. Solo la generazione di trappole relativa allo spaceremettitore-base è stata considerata nella formulazione del modello, essendo il fenomeno più rilevante. Ilmodello è stato utilizzato per effettuare alcuni studi di affidabilità di un amplificatore a basso rumore. Il tempocomputazionale non è significativamente influenzato dall’attivazione del modello di degrado, aumentando solodell’1%. Il modello sviluppato è compatibile con i comuni programmi di simulazione circuitale, e può essereimpiegato nella progettazione di circuiti con una migliore immunità rispetto ai fenomeni di degrado,contribuendo così a un riduzione dei tempi di progetto.