Field-Controlled Ion-Locked Polymorphic Electronics for Hardware Security

Abstract Nontechnical

Hardware counterfeiting and intellectual property piracy cost the U.S. more than $200 billion annually. A promising hardware solution is “polymorphic electronics,” in which the same circuit can be reprogramed to achieve a different functionality, thereby obscuring their original function. While conventional approaches are being explored, they use transistors with fixed polarity, which require many additional transistors to alter circuit functionality.

Alternative approaches where the polarity is not fixed require power to be continuously supplied. Here, a transistor is proposed whose polarity is set during operation, and for which a continuous voltage supply is not required to maintain the state; these attributes will reduce both power and size requirements. The polarity of the device is set by ions in a custom synthesized ion-conductor that are locked into place at the surface of the device.

Demonstrating such a configurable transistor represents a large step towards realizing polymorphic electronics to address hardware security. In addition to addressing a critical security need, another broader impact of this work is training a postdoc, graduate student and undergraduate students on a project that requires knowledge of nanoelectronics, materials science and chemistry.

Technical

Hardware security breaks are often executed in the form of malicious circuity, known as a Hardware Trojan (HT), which is a modification or insertion made by an untrusted third party. One promising hardware solution is so-called “polymorphic electronics,” which allows changing the functionality of the same circuit/cell during operation. While conventional CMOS approaches are being explored, they require a large number of Si transistors because the polarity is fixed; non-Si approaches are emerging, but they require voltage to be continuously supplied, and the triggers involved to convert the circuit from one function to another are often impractical.

Here, a Field-controlled Polarity-reconfigurable Field-Effect Transistor (FPFET) is proposed in which the polarity is set by field effect using a polarity gate voltage (VPG). Specifically, the polarity of transistors is set and locked during operation and therefore does not require VPG to be continuously supplied. The intellectual merit lies in demonstrating device-level polarity locking (i.e., n- and p-FET), programming NAND and NOR gates on-demand by field-effect, and demonstrating the operation of those gates in the absence of a continuous VPG.

The broader impacts include advancing polymorphic electronics to address hardware security, and student training at the intersection of several disciplines: device physics, materials science and chemistry.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.