Active Shield Indistinguishability in Integrated Circuits
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Solution Overview
Problem
Current security chips are vulnerable to invasive attacks, such as probing and focused ion beam (FIB) manipulation, which can bypass active shields and render the chip insecure, as existing shields can be visually identified and bypassed using diversion tracks.
Innovation Solution
An active shield is created with conductive tracks that are made indistinguishable from semi-insulating regions using selective doping and annealing, making them invisible to normal microscopy techniques, and randomized paths for each chip to prevent characterization and bypassing, combined with shield breach detection circuitry to initiate secure operation modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active shield lines are made visible for detection purposes, then breach detection capability is improved, but vulnerability to FIB bypass attacks increases
Solution Approach 1:
The patent applies the principle of visual indistinguishability by making the active shield lines appear identical to semi-insulating regions through controlled doping and manufacturing processes. The conductive lines are doped sufficiently to allow conduction while maintaining visual similarity to non-conductive regions, preventing attackers from identifying which lines are actual shield paths versus dummy lines.
Solution Approach 2:
The patent employs asymmetry by implementing randomized paths for conductive lines between different chips. Each chip has a unique random configuration of which lines are conductive and which are semi-insulating, preventing attackers from characterizing a device destructively and applying the information to other devices. This randomization creates asymmetry in the shield configuration across the chip population.
2Difficulty of detecting and measuring
If conductive lines are made visually distinct from semi-insulating regions, then ease of characterization is improved, but security against invasive attacks deteriorates
Solution Approach 1:
The patent applies homogeneity by ensuring that conductive lines and semi-insulating regions are produced using similar manufacturing techniques and appear visually identical. Both types of lines go through the same fabrication processes, and the conductive lines are doped in a way that makes them indistinguishable from semi-insulating regions under normal microscopy techniques, while still maintaining their conductive properties.
Solution Approach 2:
The patent utilizes parameter changes by controlling the doping level of the conductive lines to be sufficient for electrical conduction but not sufficient to create visual distinction. The doping concentration is carefully adjusted to fall within a specific range that maintains electrical functionality while preserving visual similarity to semi-insulating regions, thereby preventing visual identification of shield paths.
3Manufacturing precision
If deterministic shield paths are used, then manufacturing consistency is improved, but susceptibility to characterization attacks increases
Solution Approach 1:
The patent applies dynamics by introducing randomness and variability into the shield path configuration. Instead of using fixed deterministic paths, the conductive lines are randomly distributed and their paths vary between chips. This dynamic approach ensures that while each chip maintains functional shield paths, the specific configuration is unpredictable and cannot be characterized from one chip to another.
Solution Approach 2:
The patent implements preliminary action by pre-randomizing the shield path configuration during manufacturing before the chip is deployed. The random distribution of conductive lines is established during the fabrication process, creating unique shield paths for each chip before any potential attack occurs. This preliminary randomization prevents attackers from using systematic characterization methods.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively protects security chips from invasive attacks by rendering the shield paths undetectable and preventing unauthorized access, ensuring the chip operates securely even if the shield is breached.
Implementation Method 1
selectively altering the conductivity of a first portion of the additional layer by selective annealing
Implementation Method 2
The tracks are doped sufficiently to allow conduction of electronic carriers
Data Source
AI summary
A method for adding an additional layer to an integrated circuit, the method including providing an integrated circuit having an interconnect layer, depositing, over substantially all of an exposed surface of the integrated circuit, an additional layer of material whose conductivity can be altered, and selectively altering the conductivity of a first portion of the additional layer by selective annealing, to produce a sub-circuit in the additional layer, the sub-circuit being in operative electrical communication with the integrated circuit. Related apparatus and methods are also described.