The semiconductor chips driving modern-day computer processors are covered in billions of individual transistors, each of which can overheat under stress, causing steep drops in performance. To address this, a team led by researchers at Penn State has developed a microscopic thermometer, smaller than an ant's antenna, that can be integrated onto a chip to accurately track temperatures.
Using an advanced class of materials that are just a few atoms thick, known as two-dimensional (2D) materials, the team built sensors capable of differentiating subtle temperature changes in just 100 nanoseconds - millions of times faster than the blink of an eye. The sensors' extremely compact structure allows many of them to be integrated directly onto a single computer chip, offering what the researchers called incredibly efficient temperature monitoring. The team detailed their work in a paper published today (March 6) in Nature Sensors.
According to Saptarshi Das, Ackley Professor of Engineering Science, professor of engineering science and mechanics at Penn State and corresponding author on the paper, accurately monitoring the temperature of transistors - tiny devices that control the flow of electricity in a circuit - is currently one of the most challenging aspects of developing computer chips or high-performance integrated circuits.
"These chips rapidly heat up during usage, but the sensors that monitor their temperatures are not embedded within the chip," Das said. "One of the major questions researchers have had is whether it's possible to integrate temperature sensing directly into the chips, which would offer faster, more accurate readings."
A temperature sensor would have to be incredibly small to achieve this, as traditional sensors are too large and bulky to fit onto a chip directly, explained Das. To shrink their sensors into thermometers only one square micrometer across, or a tile several thousand times smaller than the width of a human hair, the team used a new class of 2D material - known as bimetallic thiophosphates - that had previously not been used in thermal sensors.
According to Das, this material's distinctive properties, specifically how ions can continue effectively move even when exposed to electrical currents, enable the sensors to demonstrate strong temperature dependence, even at extremely small sizes. This means that the material's physical properties can adjust dynamically as temperatures rise or fall.
"My research group works extensively with 2D materials, as Penn State is considered a leader in this research area," Das said. "We found that using this class of material, we could develop thermal sensors that are very fast, low power and really miniaturized so that you can place many of them on a single chip."
