Tiny thermometers offer on-chip temperature monitoring for processors

A team including Anirban Chowdhury, left, and Dipanjan Sen, right, developed an incredibly tiny thermometer that can be integrated directly onto computer chips.
Photo Credit: Jaydyn Isiminger / Pennsylvania State University
(CC BY-NC-ND 4.0)

Scientific Frontline: "At a Glance" Summary: Microscopic Thermometers for Computer Chips

• Main Discovery: A microscopic thermometer has been developed using two-dimensional bimetallic thiophosphates, allowing the sensors to be integrated directly onto computer chips for accurate, localized temperature tracking.
• Methodology: Researchers exploited the specific properties of bimetallic thiophosphates to couple the transport of both ions and electrons. By utilizing the heat sensitivity of the ions for temperature detection and the electrons for reading the thermal data, the team manufactured and embedded thousands of these sensors onto a single chip using existing electrical currents.
• Key Data: The sensors measure just one square micrometer across and can detect subtle temperature fluctuations in 100 nanoseconds. They are more than 100 times smaller and up to 80 times more power-efficient than traditional silicon-based systems, requiring no extra circuitry or signal converters.
• Significance: Embedding thermal sensors directly into processors solves a major challenge in the development of high-performance integrated circuits. It enables real-time thermal management to prevent the steep drops in performance caused by individual transistors overheating under stress.
• Future Application: This integration of two-dimensional materials provides a proof-of-concept framework for designing future ultra-compact sensors capable of measuring optical, chemical, or physical information directly alongside existing semiconductor technologies.
• Branch of Science: Materials Science, Semiconductor Electronics, and Engineering Science.
• Additional Detail: The design successfully turns a common semiconductor limitation into a functional advantage by actively utilizing ion movement—a behavior typically considered undesirable by the industry in standard transistor operation—to achieve high thermal sensitivity.

Utilizing 2D materials, the team developed their sensors to be so compact that thousands can be implemented on a single chip. An example of this is shown on the computer monitor, where a chip placed under a microscope showcases the vast array of sensors scattered over the surface.
Photo Credit: Jaydyn Isiminger / Pennsylvania State University
(CC BY-NC-ND 4.0)

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 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.”

“This is a proof of concept that shows this design can work — it can be miniaturized, it is low power and could be the next step in terms of integrating temperature monitoring directly into chips.”
Saptarshi Das, Ackley Professor of Engineering Science

According to Dipanjan Sen, engineering science doctoral candidate at Penn State and first author on the paper, this 2D material can “couple” together the transport of both ions and electrons — subatomic particles that both play different roles in energy transfer. Although improving the flow of electrons can lead to more powerful devices, better ion regulation in a system can lead to improved thermal management and monitoring, as these particles are notably sensitive to heat.

This coupling allows the tiny sensors to operate using the same electrical currents that power the overall chip, meaning they can provide extremely sensitive temperature readings, while not having a notable impact on chip performance. Das explained how recognizing this relationship was key to integrating the sensors directly on a chip.

“What is generally unwanted by industry in transistors actually is great for thermal sensing, so we really tried to exploit that in our design,” Das said. “Rather than try to remove these ions from this system, we use them to our advantage. Coupling these ions for temperature sensing and electrons for reading that thermal data allows us to have an extremely accurate but compact device.”

The team used advanced instruments in the Materials Research Institute's Nanofabrication Laboratory to manufacture the sensors and place thousands on a single computer chip. Not only is the sensor more than 100 times smaller than other leading sensor designs, it is also up to 80 times more power efficient than traditional silicon-based systems since it doesn’t need extra circuitry or signal converters.

Das said he believes that the team’s sensors could be integrated alongside existing technology to improve computer efficiency and stability. Going forward, the team plans to continue development and explore new opportunities to apply 2D materials in sensor design. According to Das, this research could be used as a framework to develop future sensors capable of measuring chemical, optical or physical information in an incredibly compact format.

“This is a proof of concept that shows this design can work — it can be miniaturized, it is low power and could be the next step in terms of integrating temperature monitoring directly into chips,” Das said.

Published in journal: Nature Sensors

Title: Solid-state thermometry via ionic–electronic coupling in two-dimensional heterostructures

Authors: Dipanjan Sen, Anirban Chowdhury, Safdar Imam, Anshul Rasyotra, Joan M. Redwing, Zdenek Sofer, Alireza Sepehrinezhad, Adri van Duin, Arpan Ghosh, Chen Chen, Vlastimil Mazanek, Thomas S. Ie, Mercouri G. Kanatzidis, and Saptarshi Das

Source/Credit: Pennsylvania State University | Ty Tkacik

Reference Number: eng030726_01

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