Veröffentlichungen und Präsentationen

Localized Joule heating within integrated circuit (IC) chips is the leading cause of non-uniform temperature distribution within the circuit structure of the chips. Such variation in temperature enhances the biased diffusion of metal atoms along current carrying interconnects, a phenomenon called “electromigration” that leads to interconnect degradation and is a major failure mechanism in IC products. Certain IC components, particularly for analog applications, inherently operate under such condition, including high power transistors and heater elements. As an example, on-chip embedded resistors tend to create significant localized heating under operation, which not only compromises its own electrical property and reliability but also deteriorates other components in close proximity. Therefore, characterizing detailed temperature distribution around the resistor is critical to assess the circuit performance and reliability. In this study, numerical simulation on 3D model of resistor and integrated circuit arrangement is carried on utilizing the Heat Transfer Module of COMSOL Multiphysics^® simulation software. The study provides insightful information for the design of hypothetical embedded resistor structures that meet certain performance and reliability expectation. Parametric studies are performed to determine sizes of the 3D finite element models that sufficiently represent realistic microscale samples embedded in silicon oxide. The large ratio between the insulator size for the IC and the dimension of metal lines requires non-uniform mesh density distribution so that unnecessary refinement can be avoided. Furthermore, the symmetry of the problem allows only half of the sample to be modeled. This further reduces the large computational scale of this problem. The excessive heat generation is modeled as either volumetric heat source applied in the resistor or Joule heating effects induced by the application of electric current on metal wires. Here, the Electromagnetic Heating multiphysics coupling is employed to carry out the Joule heating effects. Experiment results show an average of 100 degrees C Joule heating temperature when 100 mA current is introduced. This data are used to verify the simulation outcome of our basic models. The simulation shows parabolic temperature profiles along the resistor body resembling expected outcomes. Based on the simulation results and experimental calibration, reliability of embedded resistor design can be estimated and optimized with quick turnaround time before implementing lengthy and costly fabrication. In particular, the implication of wiring interconnect architecture on the temperature and current distribution will be analyzed. Plausible reliability degradation mechanism associated with each resistor structure design will be presented.