Breaking through the heat management barrier in 3D integrated circuits, a new benchmarking chip tests cooling solutions for stacked microelectronics, paving the way for high-performance processors and specialized chips to be packaged closely together.
The Challenge of Heat Management in 3D Integrated Circuits
As demand grows for more powerful and efficient microelectronics systems, industry is turning to 3D integration – stacking chips on top of each other. This vertically layered architecture could allow high-performance processors, like those used for ‘artificial intelligence,’ to be packaged closely with other highly specialized chips for communication or imaging.
Three-dimensional (3D) integration is a technique used to stack multiple layers of transistors and interconnects on top of each other, increasing the density of electronic devices.
This approach enables faster and more efficient data processing by reducing signal delay and power consumption.
3D integration uses various methods such as through-silicon vias (TSVs) and monolithic 3D integration to achieve this goal.
The technology has applications in fields like artificial intelligence, high-performance computing, and mobile devices.
However, technologists everywhere face a major challenge: how to prevent these stacks from overheating. In traditional single-chip designs, heat can be managed by cooling from above or below. But when multiple chips are stacked on top of each other, the heat has nowhere to escape.
A New Benchmarking Chip for Cooling Solutions
To address this challenge, MIT Lincoln Laboratory has developed a specialized chip to test and validate cooling solutions for packaged chip stacks. The chip dissipates extremely high power, mimicking high-performance logic chips, to generate heat through the silicon layer and in localized hot spots.
Cooling solutions refer to methods and technologies designed to manage heat in various environments, including buildings, vehicles, and electronic devices.
These solutions can be passive, such as using insulation or ventilation, or active, involving the use of cooling systems like air conditioning or refrigeration.
Effective cooling solutions are crucial for maintaining thermal comfort, preventing overheating, and protecting equipment from damage.
Statistics show that proper cooling can increase productivity by up to 10% and reduce energy consumption by 20%.
Cooling solutions have a long history, with ancient civilizations using techniques such as evaporative cooling in hot climates.
The chip measures temperature changes as cooling technologies are applied to the packaged stack. When sandwiched in a stack, the chip allows researchers to study how heat moves through stack layers and benchmark progress in keeping them cool.
A Breakthrough in Cooling Technology
According to Chenson Chen, who led the development of the chip with Ryan Keech, ‘If you have just a single chip, you can cool it from above or below. But if you start stacking several chips on top of each other, the heat has nowhere to escape.‘
The benchmarking chip is now being used at HRL Laboratories, a research and development company co-owned by Boeing and General Motors, as they develop cooling systems for 3D heterogenous integrated (3DHI) systems.
Applications in the Department of Defense
For the Department of Defense, 3DHI opens new opportunities for critical systems. For example, 3DHI could increase the range of radar and communication systems, enable the integration of advanced sensors on small platforms such as uncrewed aerial vehicles, or allow artificial intelligence data to be processed directly in fielded systems instead of remote data centers.
The Department of Defense (DoD) is a federal executive department responsible for the United States' defense and military operations.
Established in 1947, it oversees the Army, Navy, Air Force, Marine Corps, Space Force, and Coast Guard.
The DoD is headed by the Secretary of Defense, who is appointed by the President.
The department's budget accounts for approximately 15% of the federal government's expenditures, making it one of the largest government agencies in terms of spending.
A Collaborative Effort
The test chip was developed through collaboration between circuit designers, electrical testing experts, and technicians in the laboratory’s Microelectronics Laboratory. The team served two functions: generating heat and sensing temperature.
‘We adapted our existing silicon technology to essentially design chip-scale heaters,’ says Chen. In the 2000s, he helped the laboratory pioneer the fabrication of two- and three-tier integrated circuits, leading early development of 3D integration.
The chip’s heaters emulate both the background levels of heat within a stack and localized hot spots. Temperature-sensing elements on the chip read out the temperature in multiple locations across the chip as coolants are applied.
A New Frontier for Microelectronics
Stacked architectures are considered the next frontier for microelectronics, according to Keech. ‘We want to help the U.S. government get ahead in finding ways to integrate them effectively and enable the highest performance possible for these chips.’
The laboratory team presented this work at the annual Government Microcircuit Applications and Critical Technology Conference (GOMACTech), held March 17-20.
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