Integrated Circuit Backside Laser Attack Detection
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Solution Overview
Problem
Integrated circuits are vulnerable to attacks using laser beams due to the inaccessibility of the backside of the substrate, where passive or active shields are ineffective, and the complexity and cost of forming a protective shield on the backside pose significant challenges.
Innovation Solution
Incorporating photodiodes between components of the integrated circuit to detect light intensity changes, with a comparing circuit that activates a detection signal when the light intensity exceeds a threshold, distinguishing between ambient light and a laser beam attack, and distributing these photodiodes randomly or in a matrix configuration near sensitive components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If passive shields are formed on the circuit's layers to protect against laser attacks, then the circuit is protected to some extent, but the shields can be removed or pierced without detection and are ineffective against backside attacks
Solution Approach 1:
The patent merges the protection function with existing circuit components by integrating photodiodes into the interconnection layers between active areas. Instead of adding separate shield structures, the protection mechanism is combined with the existing layered structure of the integrated circuit, allowing detection of laser attacks without requiring additional complex shield components.
Solution Approach 2:
The patent introduces photodiodes as intermediary elements that detect laser attacks by converting light signals into electrical signals. These photodiodes act as mediators between the potential attack (laser beam) and the circuit's response, enabling indirect detection of attacks through the interconnection layers without direct contact with the active areas.
2Ease of operation
If the substrate is thinned from the backside to free the active area for accessibility, then the active area becomes accessible, but the circuit becomes vulnerable to laser beam attacks
Solution Approach 1:
The patent implements preliminary protection measures by forming photodiodes in the interconnection layers before the substrate thinning process. This allows the detection mechanism to be in place before the circuit becomes vulnerable, enabling early detection of laser attacks once the active area is exposed through backside thinning.
Solution Approach 2:
The patent applies local quality by placing photodiodes specifically in the interconnection layers between active areas rather than uniformly across the entire circuit. This localized approach provides targeted protection in the regions most susceptible to laser attacks while maintaining the overall functionality of the thinned substrate structure.
3Measurement precision
If photodiodes are formed between components of the circuit to detect light, then detection capability is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent merges the photodiode formation process with existing manufacturing steps in the integrated circuit fabrication process. By integrating photodiode creation into the standard interconnection layer formation sequence, the detection capability is added without requiring separate, complex manufacturing processes or additional fabrication equipment.
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
This method effectively detects laser beam attacks without increasing manufacturing costs or complexity, as photodiodes can be integrated into existing production lines and provide robust protection against backside attacks by identifying light intensity changes indicative of an attack.
Implementation Method 1
A laser beam can indeed be used to read by photo-electric effect the content of a memory or of registers formed in the area AL or to detect signals sent by interconnection lines.
Data Source
AI summary
A method for detecting an attack, such as by laser, on an electronic microcircuit from a backside of a substrate includes forming the microcircuit on the semiconductor substrate, the microcircuit comprising a circuit to be protected against attacks, forming photodiodes between components of the circuit to be protected, forming a circuit for comparing a signal supplied by each photodiode with a threshold value, and forming a circuit for activating a detection signal when a signal at output of one of the photodiodes crosses the threshold value.