MOSCAP Breakdown PUF Cell Array for Unpredictable Security Bits
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Solution Overview
Problem
Existing PUF devices lack a reliable method to harness the unique variations in integrated circuits for secure and predictable output.
Innovation Solution
A PUF device is fabricated with a PUF cell array containing unit cells with transistors and two metal-oxide semiconductor capacitors (MOSCAPs). By transmitting a voltage through the transistor to both MOSCAPs, the device determines which MOSCAP reaches a breakdown, assigning random state values to each.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage is transmitted through the transistor to both MOSCAPs to determine breakdown, then security and unpredictability are improved, but device complexity increases
Solution Approach 1:
The PUF device is divided into multiple unit cells, each containing a transistor and two MOSCAPs. This segmentation allows the system to generate multiple unique bits from each unit cell, increasing the overall security while maintaining a relatively simple basic unit structure. The segmentation of functionality across multiple identical units resolves the contradiction by distributing complexity rather than concentrating it.
Solution Approach 2:
The invention utilizes parameter changes in the MOSCAP breakdown voltage characteristics to generate unpredictable output. By controlling the voltage transmission through the transistor to both MOSCAPs and detecting which one reaches breakdown first, the system exploits natural parameter variations in semiconductor devices to achieve high security without requiring complex additional structures.
2Reliability
If MOSCAP breakdown is used to generate random state values, then unpredictability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The invention converts the harmful effect of MOSCAP breakdown (which is typically a failure mode) into a beneficial feature for generating random state values. By intentionally inducing breakdown conditions and detecting which MOSCAP fails first, the system transforms manufacturing variations and device degradation into a security advantage, resolving the contradiction between unpredictability and manufacturing precision.
3Reliability
If a PUF cell array with multiple unit cells is fabricated, then security is improved, but ease of manufacture decreases
Solution Approach 1:
The PUF cell array is segmented into multiple identical unit cells, each with the same basic structure of a transistor and two MOSCAPs. This modular segmentation allows for standardized fabrication processes while achieving high security through the collective behavior of many units. The repetitive structure simplifies manufacturing compared to creating a single complex PUF device.
Solution Approach 2:
Each unit cell in the array serves multiple functions: it generates a unique bit through MOSCAP breakdown, contributes to the overall security through its random behavior, and can be part of a larger array that scales security without changing the basic manufacturing process. This universality allows the same fabrication process to create a scalable security system.
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
This approach creates a secure and unpredictable output due to the random nature of MOSCAP breakdowns, effectively utilizing the unique variations in integrated circuits for enhanced security.
Implementation Method 1
a voltage is transmitted through the transistor to the first MOSCAP and the second MOSCAP and whether the first MOSCAP or the second MOSCAP reaches a breakdown is determined
Data Source
AI summary
A method for fabricating a physically unclonable function (PUF) device includes the steps of first providing a PUF cell array having a plurality of unit cells, in which each of the unit cells includes a transistor and a first metal-oxide semiconductor capacitor (MOSCAP) and a second MOSCAP coupled to the transistor. Next, a voltage is transmitted through the transistor to the first MOSCAP and the second MOSCAP and whether the first MOSCAP or the second MOSCAP reaches a breakdown is determined.