Thermal Sequence IC Logic Enable Fuse
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Solution Overview
Problem
Integrated circuits (ICs) are vulnerable to reverse engineering, leading to the creation of counterfeit versions and misuse of sensitive designs, and there is a need for secure on-demand provisioning of features after manufacturing.
Innovation Solution
An integrated circuit with functional logic that is disabled by default, enabled only through a thermal sequence enabling test using a set of physically distributed thermal sensors and an enabling fuse, which can be activated by a specific thermal cycle, and optionally secured with a private-public key for access control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If functional logic is enabled by default in IC, then ease of operation is improved, but security against reverse engineering and unintended use deteriorates
Solution Approach 1:
The enabling fuse is prepared and positioned in the circuit during manufacturing, but remains in a non-conducting state until the specific thermal sequence is applied. This preliminary setup allows the security mechanism to be in place before use, yet remains inactive until the authorized thermal activation sequence is performed, thus maintaining both ease of operation and security.
Solution Approach 2:
The patent changes the physical state of the enabling fuse from non-conducting to conducting through controlled thermal activation. The thermal sequence enables the fuse by heating it to a specific temperature range that activates the fusible material, thereby changing its electrical parameters from open to closed state, which enables the functional logic while maintaining security through the specificity of the thermal activation sequence.
2Measurement precision
If thermal sensors are physically distributed through the IC body, then measurement precision of thermal sequence is improved, but device complexity increases
Solution Approach 1:
The thermal sensing function is segmented into multiple distributed sensors placed at different locations within the IC body. Each sensor monitors the thermal condition at its specific location, and the combination of readings from all sensors provides precise verification of the thermal sequence. This segmentation improves measurement precision while the integrated control logic manages the complexity of coordinating multiple sensors.
Solution Approach 2:
The distributed thermal sensors serve multiple functions: they detect the thermal sequence for enabling the fuse, they verify the authenticity of the activation attempt, and they provide spatial information about where in the thermal sequence the IC is in the process. This multi-functionality justifies the added device complexity by providing comprehensive thermal monitoring capabilities.
3Reliability
If enabling fuse is used to disable functional logic, then security against unintended use is improved, but ease of manufacture deteriorates
Solution Approach 1:
The patent replaces traditional mechanical or electrical fuse activation methods with thermal activation. Instead of using physical breaking, electrical burning, or mechanical switching, the enabling fuse is activated through controlled heating to a specific temperature range. This substitution maintains the security function while simplifying the manufacturing process, as thermal activation can be more precisely controlled and integrated with existing IC fabrication processes.
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
Significantly increases the security against unintended use and reverse engineering, allowing for secure on-demand provisioning of features and customization after manufacturing.
Implementation Method 1
A set of thermal sensors are arranged in a physically distributed manner through at least a portion of the body
Implementation Method 2
activating the enabling fuse to enable the functional logic in response to application of a thermal cycle that causes the set of thermal sensors to sequentially experience a thermal condition matching a thermal sequence enabling test
Data Source
AI summary
An integrated circuit (IC) includes functional logic therein that can be enabled by application of a predefined thermal cycle. The IC includes an enabling fuse operatively coupled to the functional logic, the functional logic being disabled unless enabled by activation of the enabling fuse. A set of thermal sensors are arranged in a physically distributed manner through at least a portion of the IC. A test control macro operatively couples to the set of thermal sensors and the enabling fuse for activating the enabling fuse to enable the functional logic in response to application of a thermal cycle that causes the set of thermal sensors to sequentially experience a thermal condition matching a thermal sequence enabling test. A related method and system for applying the predefined thermal cycle are also provided.