Charge-Trapping Memory PUF Keys With Frozen Non-Volatile Storage
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Solution Overview
Problem
Existing non-volatile memory-based physical unclonable functions (PUFs) face challenges with high bit error rates due to manufacturing variability and temperature-induced resistance drift in resistive random access memory (ReRAM), making it difficult to generate and store reliable unique keys for security applications.
Innovation Solution
A method and system that utilize charge-trapping non-volatile memory cells to produce and store PUF keys, where the key generation is frozen using internal or external logic, and access is controlled through block-lock bits or authentication protocols to prevent changes, ensuring a stable and unchangeable key.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If ReRAM-based PUF is used to generate unique keys, then key generation capability is provided, but bit error rate increases due to manufacturing variability and temperature-induced resistance drift
Solution Approach 1:
The patent transitions from using ReRAM resistance values (which drift with temperature and aging) to using charge-trapping non-volatile memory threshold voltages as the PUF parameter. Threshold voltage in charge-trapping memory is significantly more stable against temperature and aging effects, thereby reducing bit error rates while maintaining key generation capability. This parameter change resolves the contradiction by selecting a more stable physical property for PUF operation.
2Reliability
If charge-trapping non-volatile memory is used for PUF key storage, then key stability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent incorporates PUF key generation and storage into the manufacturing process itself, using the inherent manufacturing variations in charge-trapping memory cells to create unique keys. By performing the PUF key creation as a preliminary action during fabrication rather than requiring post-manufacturing calibration or adjustment, the system achieves high key stability without imposing additional precision requirements beyond standard manufacturing tolerances.
3Reliability
If block-lock bits or authentication protocols are implemented to prevent key changes, then security is improved, but device complexity increases
Solution Approach 1:
The patent implements authentication protocols where the PUF key itself serves as the authentication credential. The charge-trapping memory cells inherently provide their own security mechanism through their stable physical properties, eliminating the need for complex external security hardware. The block-lock bits leverage the natural stability of the memory technology rather than requiring additional security layers, thereby achieving high security with minimal added complexity.
Data Source
AI summary
A device which can be implemented on a single packaged integrated circuit or a multichip module comprises a plurality of non-volatile memory cells, and logic to use a physical unclonable function to produce a key and to store the key in a set of non-volatile memory cells in the plurality of non-volatile memory cells. The physical unclonable function can use entropy derived from non-volatile memory cells in the plurality of non-volatile memory cells to produce a key. Logic is described to disable changes to data in the set of non-volatile memory cells, and thereby freeze the key after it is stored in the set.