VCSEL-Based Non-Destructive Erasure of MRAM Data
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Solution Overview
Problem
Existing hardware security measures for computing systems are often destructive, rendering hardware unusable after preventing attacks, and MRAM cells are susceptible to thermal activation that can alter data states without a magnetic field, compromising data integrity.
Innovation Solution
A non-destructively erasable magnetoresistive random-access memory (MRAM) structure incorporating a vertical-cavity surface-emitting laser (VCSEL) element that heats MRAM cells to alter their states, effectively erasing data without damaging the memory array, and a write circuit to rewrite data after erasure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a VCSEL element is used to heat MRAM cells for data erasure, then data security is improved through non-destructive erasure, but energy consumption increases due to laser heating requirements
Solution Approach 1:
The patent utilizes thermal activation by changing the temperature parameter of MRAM cells through VCSEL-induced heating. By controlling the laser pulse duration and intensity, the system temporarily raises cell temperature above the activation threshold to alter magnetization states, enabling non-destructive data erasure while managing energy consumption through precise thermal control
Solution Approach 2:
The patent converts the potentially harmful thermal activation effect—which can inadvertently alter data states—into a beneficial mechanism for controlled data erasure. By intentionally applying VCSEL heating, the system exploits thermal activation to systematically alter magnetization states and erase data securely, transforming a reliability concern into a security feature
2Reliability
If existing hardware security measures are implemented to prevent attacks, then system security is improved, but hardware functionality is lost due to destructive nature
Solution Approach 1:
The patent extracts the data erasure function from the overall security system by implementing a dedicated VCSEL element specifically for altering MRAM cell states. This separate erasure mechanism allows security operations to be performed independently without requiring destruction of the entire hardware system, maintaining functionality while enhancing security
Solution Approach 2:
Instead of using destructive methods to secure hardware (which eliminate functionality), the patent inverts the approach by using controlled thermal activation to reversibly alter data states. The VCSEL heating temporarily changes magnetization states during attacks, but the hardware remains fully functional afterward, allowing repeated security operations without permanent damage
3Reliability
If MRAM cells are subjected to thermal activation to alter data states, then data integrity is compromised for security purposes, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies local quality by directing VCSEL heating specifically to targeted MRAM cells or regions rather than uniform heating of the entire array. This localized thermal activation allows precise control over which data states are altered, enabling selective erasure of attacked cells while preserving others, thereby reducing overall manufacturing and thermal control precision requirements
Solution Approach 2:
The patent employs periodic laser pulsing to deliver thermal activation in controlled intervals rather than continuous heating. By using nanosecond-scale pulses, the system achieves cumulative thermal effects necessary for state alteration while allowing heat dissipation between pulses, reducing peak temperature requirements and easing manufacturing precision constraints
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 solution allows for non-destructive erasure of MRAM data during hardware attacks, preventing data reconstruction and maintaining memory functionality, while enabling secure rewriting of data post-attack.
Implementation Method 1
A non-destructively erasable magnetoresistive random-access memory (MRAM) structure incorporating a vertical-cavity surface-emitting laser (VCSEL) element that heats MRAM cells to alter their states
Implementation Method 2
a vertical-cavity surface-emitting laser (VCSEL) element disposed above the MRAM cell; a laser output of the VCSEL is directed toward the MRAM cell
Data Source
AI summary
An erasable magnetoresistive random-access memory (MRAM) structure and a method of making the same includes an MRAM cell disposed between bit line and word line circuit elements, and a vertical-cavity surface-emitting laser (VCSEL) element disposed above the MRAM cell. A laser output of the VCSEL is directed toward the MRAM cell.