PhD

Process Technology

• Ge and III-V CMOS scaling
• Post-CMOS nano
• Reliability research at IMEC
• Memories
• Power devices
• GaN Power Converters
• Nanoscale properties of new materials for emerging memory de
• Ion-solid interactions
• Probing semiconductor devices on the atomic scale
• Packaging and interconnection
• SiGe-based MEMS
• RF-MEMS
• Advanced lithography
• Simulation of wafer plating uniformity
• Superfilling of 3D via structures with alternative metals
• Diamond bit cutting for metal bonding

Nanoscale properties of new materials for emerging memory devices

With the development of new memory devices one needs to develop new materials with very high permittivity values (high k dielectrica for capacitors) and dielectrica which show a distinct change in conductivity depending on previous write/erase pulses. There exists at present a wide variation in materials (HfO2, NiO,..) which show this behavior. The mechanism for the change in conductivity are diverse (metal migration, oxygen migration) but in each case they can be described by the formation of a conductive filament (on the nm-scale) which promotes this conductivity. The creation and rupture of this filament is triggered by the write/erase pulse and occurs on the nm-scale. Due to their size, these filaments are extremely difficult to be observed and scanning probe methods (in particular Conductive Atomic Force Microscopy) are the only ones providing the require spatial resolution and the ability to probe the electrical behavior directly. In this project we will therefore investigate the basic of C-AFM applied on these materials, optimize the measurements procedures, explore in detail the information which can be obtained from such measurements, and subsequently study the filament formation in fundamental detail and determine their kinetics, ageing, retention and the link to material and fabrication steps and material modifications during this transformation. The fundamental work will be complemented with an assessment of the performance of macroscopic memory devices.

Responsible scientist: Wilfried Vandervorst