OTP Memory Cell 1T1R1D Structure for Disturb Current Suppression
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Solution Overview
Problem
Existing one-time-programmable (OTP) memory devices face challenges in integration with advanced integrated circuits due to large programming currents and disturb currents, which are not adequately addressed by existing 1T1R structures.
Innovation Solution
Implementing OTP memory devices with a 1T1R1D structure that includes a fuse resistor, a select transistor, and a diode in series, where the diode acts as a current divider, allowing the select transistor to be smaller and reducing disturb currents by reverse-biasing unselected cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If 1T1R structure is used for OTP memory devices, then device complexity is reduced, but programming current and disturb current become excessively large
Solution Approach 1:
The memory cell is segmented into five distinct components: select transistor, diode, fuse resistor, bit line, and word line. This segmentation allows independent optimization of each component's function, enabling the select transistor to control current flow while the diode provides directional conduction, thereby reducing the overall programming current requirement compared to a simpler 1T1R structure.
Solution Approach 2:
The diode acts as an intermediary component between the select transistor and the fuse resistor. It mediates the current flow by providing unidirectional conduction and reverse-blocking characteristics, which helps to control and reduce the programming current while maintaining effective fuse programming capability.
2Device complexity
If 1T1R structure is used for OTP memory devices, then device complexity is reduced, but disturb current increases significantly
Solution Approach 1:
The diode serves as a mediator that blocks reverse current flow to unselected memory cells. By positioning the diode between the select transistor and fuse resistor, it prevents disturb current from affecting adjacent cells during programming operations, thus reducing the harmful disturb current effect.
Solution Approach 2:
The harmful disturb current is extracted and blocked by the diode's reverse-blocking property. The diode selectively allows current flow only in the forward direction for selected cells while blocking reverse current paths that would otherwise cause disturb current in unselected cells.
3Quantity of substance
If select transistor size is reduced, then integration density increases, but programming efficiency decreases
Solution Approach 1:
The diode acts as an intermediary that amplifies the current control capability of the select transistor. By utilizing the diode's current multiplication effect in reverse breakdown mode, a smaller select transistor can still deliver sufficient programming current to the fuse, thereby maintaining programming efficiency while reducing transistor size for higher integration density.
Solution Approach 2:
The operating parameters of the diode are changed by utilizing its reverse breakdown characteristic. By operating the diode in reverse breakdown mode, the current flow is controlled and multiplied, enabling smaller transistors to achieve the same programming effect, thus improving integration density without sacrificing programming efficiency.
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 1T1R1D structure enables efficient programming while suppressing disturb currents, allowing for a larger number of OTP memory cells in advanced integrated circuits without significant leakage, maintaining programming efficiency.
Implementation Method 1
selecting a first one of the plurality of OTP memory cells to be programmed by forward-biasing the diode of the first OTP memory cell
Implementation Method 2
unselecting a second one of the plurality of OTP memory cells to be programmed by reverse-biasing the diode of the second OTP memory cell
Data Source
AI summary
A device includes a doped well, a transistor, a diode, a current-divider line, and a conductor fuse. The transistor is over the doped well. The diode is over the doped well. A first source and drain terminal of the transistor serves as a first terminal of the diode. The current-divider line is over the transistor and the diode and is electrically connected to a second terminal of the diode. The conductor fuse is over the current-divider line and is electrically connected to the first terminal of the diode.