Vanadium Dioxide-Based Films for Randomizing Integrated Circuits Photonic Emission and Absorption – VO2Random

Integrated circuits emit near-Infrared radiations and are sensitive to them. This emission is unavoidable as it is linked to the nature of the semi-conductors used in microchips, and will vary if a transistor is turned on or off. This "photonic channel" can thus be exploited to passively observe the state of a circuit, or even to modify it as a laser beam can trigger the passage of a current. Such passive and active attacks are used to access the data stored in integrated circuits or to retro-engineer their architecture. Mitigating those attacks is thus mandatory to ensure the security of integrated circuits. Here we propose coating the circuits' substrates with vanadium dioxide-based thin films, a thermochromic material that is transparent at low temperature and reflective at higher temperature. The usual transition temperature of this material, 68 °C, can be tailored by modifying its nanostructure or by doping with various atoms, and will be adapted to the working temperature of the protected circuits. The natural, and local, temperature fluctuation of the circuit, coupled with the hysteresis of the vanadium dioxide thermal transition, will ensure that the emission of a circuit strongly depends on both its temperature and its temperature history, parameters which are not easily accessible during attacks. Active attacks will be even more mitigated as they induce a temperature change in the circuit. Finally, to enhance the changes induced by the temperature fluctuation, vanadium dioxide will be included in resonant photonic microstructures. The final goal of this project is thus to present a new, original, cost-efficient and scalable method of preventing the exploitation of integrated circuits photonic emission and sensitivity.