My first words go to Professor Siegfried Selberherr whose guidance and advise were crucial for this work reaching a safe harbor. His quest for excellence and managerial skills create, at the Institute for Microelectronics, an optimal working environment both in terms of human and material resources.
The discussions and cooperation with all of my colleagues were very important to this work. I want to express my special thanks to: Gerhard Rieger who introduced me to the VISTA's framework; my room mates Wolfgang Pyka and Andreas Hössinger who were always ready for a technical or non-technical discussion. Although Wolfi speaks an excellent english, he forced me to speak german and strongly contributed to development of my skills in this language; Rainer Sabelka who never lets the computer system go down. During these years he also demonstrated that ``any time is a good time for drinking a beer''; Heinrich Kirchauer, an expert in lithography and a good soccer player; Christoph Pichler and Gerhard Schrom who, on the first days, introduced me to the bars and restaurants of Vienna; and to all those who proofread my thesis.
I would like to thank professor Francisco Vaz who taught me the importance of an exact academic work during my master's studies. He and professor Pedro Guedes de Oliveira openend me the doors of working with integrated circuits.
I am very grateful to the Fundação para a Ciência e Tecnologia (former JNICT) for having supported this work.
Lembro ainda o meu amigo Vitor Tavares que ainda foi estudar para mais longe.
Por último (os que estão sempre em primeiro lugar) agradeço aos meus pais e irmãos pelo seu constante apoio e motivação e à Elda pelo seu incentivo, compreensão e amor.