Effect factors of local heat dissipation in microcircuit structure

Abstract

In the field of integrated electronic equipment manufacture, nanoscale thermal management becomes increasingly important since the local heat dissipation generates large thermal gradients on small length scales and could cause serious performance problems. Local heat dissipation origins from thermally excited terahertz waves on material surface caused by thermal fluctuation due to electron movements and lattice vibrations. A home-made Scanning Near-field Optical Microscope (SNOM), equipped with the terahertz detector named CSIP (charge-sensitive infrared phototransistor), is utilized to map nanoscale microcircuit heat distribution. The ultrahigh sensitive CSIP makes direct detection at room temperature without external illumination possible. Previous study visualized the nanoscale heat dissipation on current-carrying NiCr wires. Localized hot-spot appears to develop along narrow wires or sharp corners of bended wires while its asymmetry doesn’t match expectation. This research dedicates to explore the possible causes of the hot-spot asymmetry in microcircuits. Finite Element Method simulation suggests that the inhomogeneous current density distribution caused by electrode bias could be one of the reasons. NiCr microcircuits of same pattern with both biased and unbiased electrode are thus fabricated and brought into control experiments. Also, the alignment of near-field scanning tip is strictly controlled to preliminarily analyze the tip’s influence on nanoscale heat mapping.