Light Scattering Nanostructures to Secure Integrated Circuits Against Optical Probing Attacks

Scrambles Optical Measurements During Probing Attacks to Protect Sensitive On-Chip Information

This security mechanism for integrated circuits arranges near the transistors a layer of nanoscale silicon pyramids that scatter reflected light, disrupting the measurements necessary for optical probing attacks. Though greatly helpful for debugging circuitry failures, optical probing techniques allow attackers to access sensitive information in integrated circuits, such as personal data or intellectual property (IP). During an optical probing attack on an industry standard CMOS chip, the attacker must thin the chip’s backside silicon layer. Certain available countermeasures work by detecting this silicon thinning, but this requires additional components that are costly to integrate into standard CMOS fabrication. Other available countermeasures use sensors to detect signals from the laser probe in an attack, but the sensors must be located near the protected circuits and have significant area overhead. Furthermore, both of these defenses use active components that require additional power to detect an attack and trigger the destruction of sensitive data.

Researchers at the University of Florida have developed a silicon nanopyramid layer for integrated circuits that protects them from optical probing attacks. The nanopyramid countermeasure easily integrates into standard CMOS chip fabrication, has no area overhead, and works passively to consume no additional energy.

Application

Silicon nanopyramids in integrated circuits that disrupt optical measurements to increase security against optical probing attacks

Advantages

• Scatters reflected light to obscure measurements, preventing successful optical probing attacks
• Etches nanopyramids in silicon substrate using established techniques, integrating easily into CMOS chip fabrication
• Uses only passive components, requiring no additional power
• Adds no area overhead, preserving circuit design flexibility and device scalability
• Does not affect transistor performance, securing chips with planar or non-planar transistors

Technology

This countermeasure against optical probing attacks inserts randomly distributed silicon nanoscale pyramids into CMOS integrated circuits to disrupt standard light absorption, scattering, and reflection patterns. Since the nanostructures at the transistor layer have random size, placement, and spacing, measurements of reflection changes are not reliable for determining transistor activity and circuitry. By diffusing reflected light from the laser probe, the nanopyramids scramble the optical measurements essential for successful optical probing attacks, thereby protecting sensitive data or intellectual property in integrated circuits.