Anti-Fuse Programmable Device Area Reduction via Select Transistor Extraction
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Solution Overview
Problem
In dynamic random access memory (DRAM) chips, the use of one-time programmable (OTP) devices like anti-fuse cells for repairing defective memory cells is hindered by the large area occupied by select and programming transistors, leading to false breakdowns and tight coupling issues as chip sizes decrease, affecting repair efficiency and performance.
Innovation Solution
A programmable device design featuring a select transistor, anti-fuse cells connected via diodes, and word lines, which reduces the area occupied and minimizes coupling effects, preventing false breakdowns by eliminating doped regions under anti-fuse cells and using a metal layer to connect anti-fuse cells not adjacent to the select transistor, allowing for efficient programming and reading operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a programmable device includes a select transistor and a programming transistor, then the device can perform programming operations, but the area occupied by the device becomes relatively large
Solution Approach 1:
The patent extracts the programming transistor from the traditional programmable device structure, leaving only the select transistor. The programming function is achieved through the anti-fuse cell breakdown mechanism controlled by the select transistor, eliminating the need for a separate programming transistor and reducing device area.
Solution Approach 2:
The patent merges the programming function into the select transistor operation. The select transistor serves dual purposes: selecting the anti-fuse cell and simultaneously programming it through controlled breakdown, combining what were previously separate functions into a single component.
2Quantity of substance
If chip size is reduced, then integration density increases, but false breakdown between adjacent transistors occurs
Solution Approach 1:
The patent introduces a diode as an intermediary component between the select transistor and the anti-fuse cell. This diode structure with its specific doping configuration acts as a barrier that prevents false breakdown from propagating to adjacent cells, enabling closer spacing of components while maintaining reliability.
Solution Approach 2:
The patent implements local quality variations through different doping concentrations in the diode structure (first doped region with first concentration, second doped region with second concentration). This localized doping strategy creates specific electrical characteristics that prevent false breakdown while enabling high integration density.
3Area of stationary object
If programmable devices are placed closer together, then chip area is reduced, but tight coupling between transistors affects performance
Solution Approach 1:
The patent removes the programming transistor that caused coupling issues with adjacent transistors. By eliminating this component, the device achieves smaller footprint without the performance degradation from tight coupling, as the select transistor alone has reduced interaction with neighboring devices.
4Reliability
If doped regions are present under anti-fuse cells, then electrical connection is provided, but false breakdown affects adjacent anti-fuse cells
Solution Approach 1:
The diode structure serves as an intermediary between the doped regions and the anti-fuse cell. It provides the necessary electrical connection while its specific doping configuration (with different concentrations in different regions) prevents false breakdown from affecting adjacent cells, filtering out the harmful effect while maintaining useful connectivity.
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 design reduces the area occupied by the programmable device, improves performance by minimizing coupling effects, and prevents false breakdowns between anti-fuse cells, enhancing the efficiency of repair operations and overall device performance.
Implementation Method 1
applying a third voltage to a word line corresponding to the anti-fuse cell required to be programmed, so that the anti-fuse cell required to be programmed is broken down
Data Source
AI summary
Provided are a programmable device, a programmable device array, operation methods therefor, and a memory. The programmable device includes: a bit line; a select transistor, a first source/drain of the select transistor being electrically connected to the bit line; a select signal line, the select signal line being electrically connected to a gate of the select transistor; a plurality of diodes; a plurality of anti-fuse cells, a first end of each one of the plurality of anti-fuse cells being electrically connected to a second source/drain of the select transistor via a corresponding one of the plurality of diodes; and a plurality of word lines, each one of the plurality of word line being electrically connected to a second end of a corresponding one of the plurality of anti-fuse cells.