Anti-Fuse OTP Memory Cell Asymmetrical Channel Width Design
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Solution Overview
Problem
Existing anti-fuse type OTP memory cells require a redundancy scheme due to their single-programmable nature, leading to increased decoder area and complexity, and limited programming efficiency due to channel width constraints.
Innovation Solution
The design includes a pair of anti-fuse transistors and selection transistors with asymmetrical channel widths, where the selection transistors have wider channel widths than the anti-fuse transistors, allowing for increased current flow during programming and reduced decoder area by optimizing the layout and biasing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If anti-fuse type OTP memory cells use conventional channel width design, then device area is reduced, but programming efficiency deteriorates due to limited current flow
Solution Approach 1:
The patent applies local quality by making the selection transistor channel width different from the anti-fuse transistor channel width. Specifically, the selection transistor has a wider channel (Wsel > Waf) to increase current flow capability during programming operations, while the anti-fuse transistor maintains its original channel width. This localized differentiation allows the selection transistor to provide sufficient programming current without increasing the overall cell area, thereby resolving the contradiction between programming efficiency and device area.
2Reliability
If anti-fuse type OTP memory cells implement redundancy scheme, then reliability is improved, but decoder area and complexity increase
Solution Approach 1:
The patent applies merging by combining the selection and programming functions into a unified transistor structure. The selection transistor serves dual purposes: it selects the memory cell for operation and simultaneously provides the programming current path. This integration eliminates the need for separate programming circuitry and reduces decoder complexity while maintaining reliability through the anti-fuse mechanism's inherent one-time programmable characteristics.
3Power
If selection transistor channel width equals anti-fuse transistor channel width, then layout simplicity is maintained, but current flow during programming is insufficient
Solution Approach 1:
The patent applies parameter changes by modifying the channel width parameter of the selection transistor. The selection transistor channel width (Wsel) is explicitly designed to be greater than the anti-fuse transistor channel width (Waf). This parameter change increases the current flow capability of the selection transistor during programming operations, ensuring sufficient programming current without requiring complex multi-transistor structures. The simplified single-transistor design with adjusted width parameter effectively resolves the contradiction between programming current and structural complexity.
Data Source
AI summary
An anti-fuse type OTP memory cell includes a first anti-fuse transistor having a first channel width, a first selection transistor sharing a first active region with the first anti-fuse transistor and having a second channel width that is greater than the first channel width, a second anti-fuse transistor sharing a program gate with the first anti-fuse transistor and having a third channel width, and a second selection transistor sharing a second active region with the second anti-fuse transistor and having a fourth channel width that is greater than the third channel width.