Anti-Fuse DRAM Cell with Three-Transistor Series Structure
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Solution Overview
Problem
The increasing number of defects in DRAM devices due to gate breakdown type anti-fuses, particularly in large capacity and miniaturized DRAM structures, leads to reduced chip yield and reliability, as stable breakdown processes are difficult to achieve, and the large number of anti-fuses complicates the arrangement and detection of defective elements.
Innovation Solution
The use of anti-fuse elements comprising three serially-coupled MOS transistors, where the middle transistor's gate is programmed by voltage breakdown to alter physical properties, allowing for reliable programming and reading through current detection methods, and a redundant address circuit that compares and redirects addresses to replace defective memory cells, improving chip reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If gate breakdown type anti-fuses are used in large capacity and miniaturized DRAM structures, then the memory capacity is improved, but the manufacturing precision deteriorates due to difficulty in achieving stable breakdown processes
Solution Approach 1:
The patent employs breakdown control circuits that precisely control the voltage and current parameters during the anti-fuse breakdown process. By adjusting and optimizing these electrical parameters, the breakdown process becomes more stable and predictable, even in miniaturized structures. This allows reliable anti-fuse programming while maintaining the benefits of high-capacity, miniaturized DRAM design.
2Area of stationary object
If anti-fuses are arranged in an array to reduce area, then the area efficiency is improved, but the device complexity increases due to difficulty in carrying out breakdown processes and detecting defective elements
Solution Approach 1:
The patent designs breakdown control circuits that serve multiple functions: controlling breakdown voltage, monitoring breakdown status, detecting defective anti-fuses, and activating redundant elements. This multi-functionality reduces the need for separate dedicated circuits for each task, thereby managing complexity while maintaining area efficiency of the anti-fuse array.
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 enhances the reliability and yield of DRAM devices by stabilizing the breakdown process of anti-fuse elements and improving the detection and replacement of defective cells, thereby maintaining chip performance and reducing defects.
Implementation Method 1
the middle transistor's gate is programmed by voltage breakdown to alter physical properties
Data Source
AI summary
Apparatuses and methods including anti-fuses and for reading and programming same are disclosed herein. An example apparatus may include an anti-fuse element comprising first, second, and third transistors coupled in series between first and second nodes such that the second transistor is between the first and third transistors. The second transistor is configured to be operated such that a punch-through current flows through the second transistor to indicate that the anti-fuse element has been programmed.