UCLA engineers have demonstrated the successful integration of a new type of semiconductor material into high-power computer chips to reduce the processor’s heat and improve its performance. This advancement has greatly improved the energy efficiency of computers and can remove heat outside the best thermal management equipment currently available.

Electron microscope image of gallium nitride-boron arsenide heterojunction interface at atomic resolution

The research was led by Hu Yongjie, associate professor of mechanical and aerospace engineering at UCLA Samuel School of Engineering. Nature Electronics recently published this finding in this article.

Over the years, computer processors have shrunk to the nanometer level, with billions of transistors on a single computer chip. Although the increase in the number of transistors helps make computers faster and more powerful, it also creates more hot spots in highly dense spaces. If there is no effective way to dissipate heat during operation, the computer processor will slow down and make calculations unreliable and inefficient. In addition, the highly concentrated heat and soaring temperature of computer chips require additional energy to prevent the processor from overheating.

To solve this problem, Hu and his team took the lead in developing a new type of ultra-high thermal management material in 2018. Researchers have developed defect-free boron arsenide in their laboratory and found that it is more effective in absorbing heat and dissipating heat compared to other known metal or semiconductor materials such as diamond and silicon carbide. Now, the team has successfully demonstrated the effectiveness of the material for the first time by integrating it into high-power equipment.

In their experiments, the researchers used a computer chip and a state-of-the-art wide band gap transistor made of gallium nitride, called a high electron mobility transistor (HEMT). When the processor is running at near maximum capacity, chips that use boron arsenide as a heat sink show a maximum heat increase from room temperature to close to 188 degrees Fahrenheit. This is significantly lower than a chip that uses diamond to dissipate heat, where the temperature rises to about 278 degrees Fahrenheit, or a chip that uses silicon carbide shows a heat increase to about 332 degrees Fahrenheit.

Schematic diagram of microchip packaging and the use of heat sinks to cool electronic chips

These results clearly show that compared with processors using traditional thermal management materials, boron arsenide devices can maintain higher operating power. Hu said that our experiments were done under conditions where most current technologies would fail. This development represents a new benchmark performance and shows great application potential in high-power electronics and future electronic packaging.

According to Hu, boron arsenide is ideal for thermal management because it not only has excellent thermal conductivity, but also has low heat transfer resistance.

When heat crosses the boundary from one material to another, the speed of entering the next material usually slows down. Nonsense, the main feature of our boron arsenide material is its very low thermal boundary resistance. It's a bit like the heat only needs to cross the curb instead of jumping over obstacles.

The team also developed boron phosphide as another excellent heat sink candidate. In their experiments, the researchers first demonstrated the use of boron arsenide to build semiconductor structures, and then integrated the material into the HEMT chip design. The successful demonstration opened the way for the industry to adopt the technology.