Hardware Trojan Scanner Using SEM Image Comparison
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Solution Overview
Problem
Conventional methods for detecting hardware Trojans in integrated circuits (ICs) are inefficient, consuming significant resources, unreliable, and unable to effectively identify stealthy dopant level Trojans, especially in critical infrastructure and military applications.
Innovation Solution
A method involving SEM imaging and image processing techniques, including image registration, enhancement, and feature extraction, combined with machine learning algorithms to compare Trojan-free and suspect IC images, to detect changes indicative of hardware Trojan presence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If run-time monitoring technique is used to detect hardware Trojans, then Trojan detection capability is provided, but CPU usage, power consumption, memory usage, and silicon area increase
Solution Approach 1:
The patent performs Trojan detection during the manufacturing phase using SEM imaging and image processing algorithms, rather than during runtime. By detecting Trojans before the IC is deployed, the system eliminates the need for runtime monitoring overhead, thus avoiding increased power consumption, CPU usage, and silicon area while maintaining detection capability
Solution Approach 2:
The patent creates a digital twin or reference model of the golden IC layout and compares it with the actual IC images using image processing. This copying approach allows detection without modifying or adding physical monitoring hardware to the IC, thereby avoiding additional silicon area and power consumption
2Reliability
If logic testing methods are used to detect hardware Trojans, then some Trojans can be detected, but large Trojans cannot be easily detected because it is difficult to generate test vectors that trigger the Trojans
Solution Approach 1:
The patent transitions from functional testing (logic testing) to physical imaging (SEM images). By changing the detection dimension from electrical behavior to physical structure, the system can detect large Trojans that are invisible to logic testing, as the image processing directly reveals physical modifications regardless of their functional impact
Solution Approach 2:
The patent replaces the electrical/mechanical logic testing system with an optical imaging system (SEM). This substitution allows direct visualization and detection of physical Trojans without needing to generate complex test vectors, making large Trojans easily detectable through image comparison
3Reliability
If side channel analysis is used to detect hardware Trojans, then some Trojans can be detected, but small size Trojans cannot be detected due to vulnerability to circuit noise
Solution Approach 1:
The patent creates high-resolution SEM images as digital copies of the IC physical structure and uses image processing to enhance and compare these copies. This copying approach allows detection of small Trojans by comparing detailed structural features without being affected by circuit noise that plagues side channel analysis
Solution Approach 2:
The patent performs image enhancement and feature extraction preprocessing on the SEM images before comparison. By preliminarily enhancing the image quality and extracting relevant features, the system improves measurement precision for small Trojans, making them detectable despite their small size, unlike noisy side channel analysis
4Reliability
If reverse engineering is used to detect hardware Trojans, then Trojan detection can be achieved, but the process is expensive and slow, and many ICs are destroyed in the process
Solution Approach 1:
The patent extracts only the necessary visual information from IC images using targeted image processing and feature extraction algorithms. Instead of performing complete reverse engineering that requires destroying multiple ICs, the system extracts relevant structural features from images for comparison, reducing time loss and IC destruction while maintaining detection capability
Solution Approach 2:
The patent uses non-destructive SEM imaging to create digital copies of the IC structure for analysis. This copying approach eliminates the need for destructive reverse engineering processes, allowing detection without destroying the ICs and significantly reducing the time and cost associated with manufacturing and testing multiple samples
Data Source
AI summary
A method of detecting hardware Trojans in an IC includes providing a golden IC layout data set or SEM image data taken at long dwelling time on an active area of the golden IC after polishing it from the backside. Next, the IC under authentication (IUA) sample is prepared for fast SEM imagining (shorter dwelling time) after backside thinning. Next step is to perform image processing on the IUA's SEM image, which includes histogram equalization with noise filtering using Gaussian and Median filters. In the last step, the IUA sample data with the shorter dwelling time is compared with the golden IC layout data or the golden image data from high quality (longer dwelling time) SEM scanning process. At the end the result of the comparison is used to identify hardware Trojans.