Camouflaged Multiplexer Cell Layout Using Real and Fake Contacts
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Solution Overview
Problem
Reverse engineering of semiconductor chips poses a risk of intellectual property theft, as existing technologies fail to effectively conceal the circuit design and functionality, making it difficult to protect the design from attackers who can decipher the structure through delayering and image processing.
Innovation Solution
Implementing a camouflage design using a multiplexer cell with a universal gate that incorporates real and fake contacts, where fake contacts are used to disguise the actual circuit functionality, making it challenging for attackers to distinguish between real and fake contacts during the delayering process, thereby hiding the circuit design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional circuit layout is used, then the circuit functionality is clear and easy to manufacture, but the design is vulnerable to reverse engineering and intellectual property theft
Solution Approach 1:
The circuit is segmented into functional units (e.g., multiplexer cells) that can be independently designed and analyzed. Each unit contains multiple contacts that are individually configured to contribute to the overall camouflage effect while maintaining functional integrity
Solution Approach 2:
Different regions of the circuit layout are assigned different contact configurations (real vs. fake contacts) to create local variations that collectively provide camouflage. The contact density, spacing, and positioning are locally optimized to mimic genuine circuit patterns while protecting specific functional areas
2Difficulty of detecting and measuring
If fake contacts are added to disguise circuit functionality, then reverse engineering becomes difficult, but the manufacturing process becomes more complex
Solution Approach 1:
The formation of real and fake contacts is merged into a single fabrication process sequence. Both types of contacts are created using the same deposition and patterning steps, eliminating the need for separate manufacturing processes and reducing overall manufacturing complexity
Solution Approach 2:
The contact structure is designed to serve multiple functions: genuine electrical connection for real contacts and visual deception for fake contacts. The universal contact formation process handles both functions simultaneously, while the underlying structure can be configured differently to achieve either real or fake contact behavior
3Ease of manufacture
If all contacts are made identical in structure, then manufacturing is simplified, but attackers can easily distinguish real from fake contacts during delayering
Solution Approach 1:
While maintaining overall structural symmetry for manufacturing efficiency, asymmetric variations are introduced in specific contact configurations. These asymmetric features (e.g., slight dimensional variations, different spacing patterns) are subtle enough not to complicate manufacturing but sufficient to create distinguishable patterns during reverse engineering analysis
Data Source
AI summary
A semiconductor device includes a semiconductor substrate, a conductive segment, a conductive layer, a first contact element and a second contact element. The semiconductor substrate includes an active region. The conductive segment is formed on the semiconductor substrate, and extends across the active region. The conductive layer is formed over the semiconductor substrate and the conductive segment. The first contact element, formed between the conductive segment and a first conductive portion of the conductive layer, is arranged to electrically connect the conductive segment to the first conductive portion. The second contact element is formed between the conductive segment and a second conductive portion of the conductive layer. The first contact element and the second contact element are formed on the conductive segment and spaced apart from each other. The second contact element is arranged to electrically isolate the conductive segment from the second conductive portion.