Mechanical stress in semiconductor devices can drastically degrade the device performance. These effects become increasingly important for the new generations with smaller dimensions. Convergent beam electron diffraction (CBED) in a transmission electron microscope is the only technique that has adequate spatial resolution to measure the stress in these advanced structures but needs further development in terms of procedures and results interpretation. The site-specific specimen preparation for small device structures that include Cu/ low-k metallization requires the use of Focused Ion Beam (FIB) thinning. The effect of this thinning procedure on the stress distribution needs further investigation. The research project will focus on:
1) CBED analysis of advanced devices with small dimensions (0.10-0.18 micron) and new materials(new silicides, SiGe, Cu/ low-k metallization),
2) The interpretation and optimization of the strain/stress analysis of these structures (room temperature measurements, energy filtering, use of new zone axes , advanced simulations),
3) The development of an in-site plucker system for site-specific FIB preparation of these structures and the investigation of the effect of the FIB preparation on the measured mechanical stress,
4) The application of the in-situ plucker to the study of stress induced deformation in Cu/ low-k dielectric stacks. The training will be a combination of research work and attending courses and seminars. The research work will involve: the development of new procedures for Convergent Beam Electron Diffraction, the technical design and development of an in-site plucker system, acquiring skills on Focused Ion Beam, extending knowledge on advanced processing, collaboration in a large research team, the internal and external reporting. Training courses will be: the semiconductor processing courses of the MCT training centre, weekly internal seminars, lectures given by invited experts, and the post-graduate courses of the KU Leuven-university. The training will allow the application to enhance his knowledge of materials characterization and advanced device processing, and to get full insight in the future evolutions of semiconductor industry. Therefore, he will achieve a strong background in semiconductor technology and become an expert in-line with the industrial needs.