Electric breakdown of dielectric systems containing air in interconnects for nodes <A10

Metal interconnects handle power and signal distribution in electronic circuits between transistors and to the outside world.  To enable performance gains of circuits, the width of and the spacing between these interconnects need to shrink to below 10 nm in the coming decades. In the most advanced technologies, the material separating lines from each other contains a good amount of … air.

Although such advanced nano-interconnects are awesome from a performance point-of-view, their electrical durability is heavily challenged. During operation, electrical fields between different interconnect lines are as high as 100 mV per nm and these fields need to be maintained for over 5 years. It is generally understood that such high fields generate defects in the dielectrics separating the lines. Such defects form sides for electron trapping and de-trapping. At long stress times, defects accumulate and form local conductive paths leading to a loss of the isolating properties of the dielectric system.

Where the physical and statistical processes of dielectric degradation is understood for more classical interconnect systems with only dielectrics as isolating material (no air), this PhD is about unravelling the physical and statistical processes behind the breakdown of nano-scaled dielectric systems consisting of air, dielectrics and the interfaces between them. Dedicated experiments to understand the electrical conduction and degradation through/of such hybrid dielectric systems need to be performed. In parallel, physics- and statistics-based models on how defects are generated and how they accumulate leading to final breakdown need to be developed.

The final aim of the PhD is to understand the electrical robustness of these nano-interconnects and to predict their electrical breakdown behavior at even further scaled dimensions.

The supervisors of this PhD are world-recognized experts from both KU Leuven and imec in the field of metrology and reliability. Existing insights from dielectric breakdown studies in gate oxides and more classical interconnect dielectric systems can serve as a basis for this work.