At the IEEE 3DIC in SF in October DARPA program manager Avi
Bar Cohen presented the history of device cooling at DARPA and how it has
evolved to the embedded cooling of 3D stacks.
It is well known that microprocessor frequency stopped
increasing around 2005 when air cooling met its limits.
Traditional cooling involves heat rejection to a remote
fluid involving thermal conduction and spreading in substrates across multiple
material interfaces as shown below.
Such technology cannot:
- limit the device
“junction” temperature - selectively target the thermally-critical devices - extract heat efficiently from a 3D package or 3DIC stack
What is needed to take us to the next level is an embedded
cooling solution at the die level. As we have discussed before [ see IFTLE xxx
] the DARPA ICECool program is divided into fundamental and applications phases
with the goal of providing “.. the fundamental thermofluid building blocks for
the utilization of Intra and Interchip evaporative cooling in 3D DoD
electronics” . It was envisioned that inter and/or intrachip cooling would be
used to bring the cooling function directly to the site of the temperature rise
on the device.
Fundamental programs addressing the cooling of 3D stacks
include :
GaTech /
Rockwell - STAECOOL
IBM / Stanford –
Integrated Silicon Two Phase Cooling
The 3D focused portion of the ICECool applications program
has a goal of “enhancing the performance of embedded high performance computing
systems through the application of chip-level heat removal with kW-level heat
flux and heat density with thermal control of local sub millimeter hot spots”.
At the December ICECool Applications kick off meeting in WDC
Bar Cohen introduced the two 3D focused program winners GaTech / Altera
and IBM:
GaTech / Altera – SUPERCool which has the goal of bringing
microfluidic cooling to the Altera FPGA.
IBM will also participate in this phase of the contract
focusing on “ bringing embedded chip cooling to a high end server and showing
the extendability to 3DIC stacks”
For all the latest in 3DIC and advanced packaging stay
linked to IFTLE………………….
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