PUF Security Device With Antiparallel Magnetic Layers

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Solution Overview

Problem

Existing hardware-based security measures, such as physical unclonable functions (PUFs), are sensitive to ambient noise and prone to security issues over extended use due to their dependence on fine physical structure differences.

Innovation Solution

A security device incorporating a substrate with alternately arranged first and second PUF cells, each comprising a pinned magnetic layer, a free magnetic layer, and a tunnel barrier layer, with the magnetization direction of the pinned magnetic layer of the first PUF cells being antiparallel to that of the second PUF cells, and a spin-orbit torque pattern contacting the free magnetic layers to enhance random number generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional PUF structures are used, then hardware-based security is provided, but sensitivity to ambient noise and security vulnerabilities occur over extended use

Engineering Contradiction:

Improvesecurity reliabilityVSAvoidsensitivity to ambient noise

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The PUF structure is divided into multiple magnetic layers (pinned magnetic layer, free magnetic layer, tunnel barrier layer) with distinct functions. The pinned magnetic layer provides stable reference magnetization while the free magnetic layer responds to external stimuli, segmenting the security function into reliable reference and variable response components that reduce noise sensitivity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent uses composite magnetic tunnel junction structures combining different magnetic materials with specific magnetization directions. The antiparallel magnetization configuration of pinned layers creates a composite system with enhanced stability and reduced sensitivity to ambient magnetic noise while maintaining security functionality

Inventive Principle:

Principle #40Composite materials

2Reliability

If PUF depends on fine physical structure differences, then hardware security is achieved, but security issues arise when used for extended period

Engineering Contradiction:

Improvelong-term securityVSAvoidextended use duration

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The pinned magnetic layers are pre-configured with antiparallel magnetization directions during fabrication, establishing a stable reference state before operation. This preliminary configuration ensures consistent baseline behavior that prevents drift over extended use, allowing the PUF to maintain security reliability throughout its operational lifetime

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent utilizes changes in magnetization states of the free magnetic layer in response to external stimuli while maintaining the stable pinned layer configuration. By controlling the magnetic state transitions rather than relying solely on fixed physical structure differences, the system achieves both security and extended operational durability

Inventive Principle:

Principle #35Parameter changes

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 security device effectively generates random numbers and re-establishes unpredictable security keys by removing stray magnetic fields and allowing the free magnetic layers to have randomly oriented magnetization directions, thereby enhancing security and resilience against noise and prolonged use.

Implementation Method 1

a spin-orbit torque pattern extending in the first direction, wherein the spin-orbit torque patter is in contact with the plurality of first PUF cells and the plurality of second PUF cells

Methodology Applied

Scientific EffectSpin-orbit torque:

Implementation Method 2

each of the plurality of first PUF cells and the plurality of second PUF cells includes a pinned magnetic layer, a free magnetic layer, and a tunnel barrier layer disposed between the pinned magnetic layer and the free magnetic layer

Methodology Applied

Scientific EffectTunnel magnetoresistance: Magnetoresistance

Data Source

PatentUS20250175354A1Security device and method of fabricating the same

Publication Date: 2025.05.29 SAMSUNG ELECTRONICS CO LTD

AI summary

A security device includes a substrate extending in a first direction and a second direction, wherein the first direction intersects the second direction, first physical unclonable function (PUF) cells disposed on the substrate, wherein the first PUF cells are spaced apart from each other in the first direction and the second direction, and second PUF cells disposed on the substrate, wherein the second PUF cells are spaced apart from each other in the first direction and the second direction. Each of the plurality of first PUF cells and the plurality of second PUF cells includes a pinned magnetic layer, a free magnetic layer, and a tunnel barrier layer disposed between the pinned magnetic layer and the free magnetic layer.