Researchers Uncover the Inner Workings of Chips — with Non-Contact Terahertz Imaging
New approach lets you see inside the packaging and inspect exactly how electricity is flowing through the device.
Researchers have come up with a way to see exactly what's going on inside modern electronic devices while they're running — without having to physically break their way inside the chip: terahertz wave imaging.
"Once a chip is sealed inside its protective packaging, it becomes extremely difficult to tell what is happening inside it," senior author Withawat Withayachumnankul explains of the problem the team set out to solve. "Most existing inspection methods require physical electrical probes, exposed chips, or devices to be powered down — making them impractical in many scenarios. This research is a first step towards a long-standing problem in electronics. We can now observe electrical activity inside a working semiconductor device from the outside, without damaging it or interrupting its operation."
The team's work is inspired by X-ray technology, but using non-ionizing terahertz waves — peering through the packaging of an electronic component to pick up changes in electrical current, at a resolution smaller than the wavelength of the terahertz wave itself. The trick: an ultra-sensitive homodyne quadrature receiver.
"This approach allows the system to cancel out background noise and isolate the faint signal produced by electrical activity inside the device," Withayachumnankul explains of how the system works. "The result is a real-time view of electronics at work, even when the active region is buried deep inside sealed packaging. Because terahertz radiation is non-ionising and safe, the technique also offers a safer alternative to inspection methods that rely on X-rays or invasive probing. This makes it particularly attractive for safety-critical applications, such as high-power electronics, where devices cannot easily be taken offline."
Being able to investigate the inner workings of a chip after it's been packaged and without destructive decapping — a process that involves removing the packaging layer by layer, often involving precision sanding and harsh acids — also inspired a project from Andrew "bunnie" Huang, dubbed IRIS: Infrared In-situ inspection. In IRIS, chips packaged with the back side of the silicon exposed are inspected using a strong infrared light — exposing the structures within, but unlike the terahertz imaging system not how electricity is flowing through them.
"Being able to remotely and non-invasively assess electronic activity could help verify the integrity of critical hardware, detect malfunctioning or compromised components, and monitor systems where physical access is limited or undesirable," says lead investigator Chitchanok Chuengsatiansup of the potential impact of the work. "This research opens the door to smarter, self-diagnosing electronics, new ways of monitoring complex integrated circuits, and faster development of next-generation chips."
The team's work has been published under open-access terms in the IEEE Journal of Microwaves.