In recent years, the contribution of the back-end of line (BEOL) to the overall thermal resistance of advanced chip packages has become more significant and even dominant for certain applications. The current trends for the BEOL show smaller metal line dimensions, higher resistivity metals and dielectric materials with lower thermal conductivity. All these trends result in higher self-heating in the metal lines, and further increase the thermal concerns for the BEOL. The objective of this PhD is to gain fundamental understanding of the thermal transport in the metal lines and dielectric material in the BEOL and to use this insight to develop mitigation solutions for the thermal problems.
The first part of the research involves the characterization of the thermal properties of the BEOL from a modeling and an experimental point of view. For the modeling part, a modeling framework needs to be developed to study the self-heating in the metal lines and the thermal coupling from the FEOL to the BEOL and between different metal lines. This modeling approach should bridge the gap between the transistor level modeling that typically includes only part of the local interconnect and the chip level modeling. For the experimental part, test structures should be defined and characterized in order to estimate the thermal properties of the small metal lines and the dielectric material. In the second part of the research, the developed modeling framework and the extracted material properties are applied to advanced BEOL configurations such as backside power delivery networks to assess their thermal impact in 3D systems with very thin Si chips.
Required background: Master in Engineering majoring in Mechanics, Material science, Energy or Microtechnology or Master in Science (Physics, Chemistry)
Type of work: 10% literature study, 50% modeling, 30% experimental analysis, 10% reporting in meetings, conferences and journals
Supervisor: Ingrid De Wolf
Daily advisor: Herman Oprins
The reference code for this position is 1812-21. Mention this reference code on your application form.