HCI PUF Circuit With Pi-Shaped Reset for Stable Root Keys

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Solution Overview

Problem

Existing PUF circuits in electronic circuits are sensitive to environmental conditions, requiring significant error correction coding and potentially compromising security due to entropy leakage, and third-party oxide anti-fuse type PUFs are undesirable.

Innovation Solution

A hot carrier injection (HCI) PUF circuit using only PMOS or NMOS transistors with unique circuit topologies, incorporating reset and stress mechanisms to achieve low bit error rates and self-contained operation, suitable for secure root key generation and unique ID applications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If memory elements (SRAM or SA latch) are used for PUF circuit, then the PUF circuit can be implemented, but high sensitivity to environmental conditions occurs requiring large amount of error correction coding

Engineering Contradiction:

ImprovePUF circuit operationVSAvoiderror correction coding

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the physical parameters of the PUF circuit by using oxide anti-fuse structures with controlled breakdown characteristics. The asymmetric oxide layers create inherent parameter differences that are stable against environmental conditions, eliminating the need for complex error correction coding while maintaining reliability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite oxide structures with different oxide layers (first oxide layer and second oxide layer with different breakdown voltages) to create the PUF circuit. This composite material approach provides environmental stability while generating the required randomness, resolving the contradiction between reliability and complexity.

Inventive Principle:

Principle #40Composite materials

2Reliability

If memory elements (SRAM or SA latch) are used for PUF circuit, then the PUF circuit can be implemented, but entropy leakage occurs making the solution less secure

Engineering Contradiction:

ImprovePUF circuit operationVSAvoidentropy leakage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the typically harmful oxide breakdown phenomenon into a beneficial security feature. The stochastic breakdown of oxide anti-fuse structures creates unclonable keys without entropy leakage, as the breakdown process is inherently random and irreversible, transforming a reliability concern into a security advantage.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Object-affected harmful factors

If third party oxide anti-fuse type PUF is used, then security is improved, but device complexity and manufacturing issues arise

Engineering Contradiction:

ImprovesecurityVSAvoidPUF circuit structure

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent merges the PUF functionality directly into the existing memory cell structure using oxide anti-fuse elements. This integration eliminates the need for separate third-party PUF circuits, reducing device complexity while maintaining security through the inherent properties of the oxide breakdown process.

Inventive Principle:

Principle #5Merging (Combining)

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 HCI PUF circuit achieves near-zero bit error rates, is cross-foundry portable, and eliminates the need for external helper data, providing enhanced security and efficiency in secure key generation and unique ID functions.

Implementation Method 1

Hot carrier injection (HCI) PUF circuit

Methodology Applied

Scientific EffectHot carrier injection:

Data Source

PatentUS12556180B2Hot carrier injection hardened physically unclonable function circuit

Publication Date: 2026.02.17 INTEL CORP

AI summary

Various embodiments provide apparatuses, systems, and methods for a hot carrier injection (HCI) physically unclonable function (PUF) circuit. For example, described herein is a HCI PUF circuit with n-type metal oxide semiconductor (NMOS) transistors and a Pi-shaped reset structure. Other embodiments may be described and claimed.