Numerical Analysis of Liquid Cooling of 3D-ICs Using Embedded Channels

TL;DR

This paper uses numerical analysis to compare the effectiveness of different liquid coolants in managing hot spots in 3D integrated circuits with embedded channels, highlighting the trade-offs between temperature reduction and stress.

Contribution

It introduces a detailed numerical study of embedded channel cooling in 3D-ICs, comparing water, Freon, and liquid nitrogen for thermal and stress management.

Findings

LN achieves the lowest temperature (164 K) but causes highest stress (355 MPa)

Parallel channel cooling leads to temperature and stress variation

Designing cooling systems to eliminate high-stress hot spots is crucial

Abstract

Hot-spots are considered among the unavoidable consequences of the high integration density of 3D-ICs. Eliminating hot spots requires employing efficient cooling techniques. Using embedded channels, liquid cooling systems can be designed to deliver the right amount of coolant to each spot of the chip. In this study, numerical analysis is used to investigate the cooling of a 20 W hot spot using embedded channels employing three coolants: water, Freon (R22), and liquid nitrogen (LN). The investigation of thermal management and stress show that, although LN provides the lowest operating temperature (164 K), it causes the highest stress (355 MPa) at 100 mm/s inlet velocity. The study also shows that, coolant delivery using parallel channels results in a wide variation of local temperatures and stress. This stress variation may form high-stress spots, which may cause circuit failure, performance degradation, or yield reduction. Therefore, cooling systems and chip fabrication should be designed to ensure the elimination of high-stress hot spots.