Memory Cell Programming via Localized Voltage Differentiation
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Solution Overview
Problem
Existing non-volatile memory devices face challenges in programming efficiency due to issues like punch-through in unselected cells and reduced integration density, especially when cells share a source/drain (S/D) region, leading to inefficiencies in hot electron injection.
Innovation Solution
A method of programming a memory cell that shares an S/D region with another cell by applying specific voltage differences across the S/D regions to enhance hot carrier injection efficiency, preventing punch-through in unselected cells and improving programming speed by optimizing the voltage applied to the shared S/D region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If cells share an S/D region to reduce area, then integration density is improved, but programming efficiency deteriorates due to electron scattering
Solution Approach 1:
The patent applies different voltage levels to different S/D regions: the first S/D region receives a first voltage, the shared second S/D region receives a second voltage (between first and third voltages), and the third S/D region receives a third voltage. This localized voltage differentiation creates favorable electric field conditions in the first cell's channel while maintaining shared S/D region architecture, thereby preserving both high integration density and programming efficiency
Solution Approach 2:
The patent changes the voltage parameters applied to S/D regions to optimize hot carrier injection. By setting the second voltage on the shared S/D region between the first and third voltages, the electric field distribution is optimized to enhance carrier acceleration and injection efficiency without increasing cell area, thus resolving the contradiction between integration density and programming efficiency
2Reliability
If voltage is raised to prevent punch-through in unselected cells, then reliability is improved, but programming efficiency deteriorates
Solution Approach 1:
The patent applies different voltage levels to different S/D regions to create localized electric field conditions. The shared second S/D region receives an intermediate voltage that prevents punch-through in unselected cells while maintaining favorable conditions for hot carrier injection in selected cells, thus simultaneously achieving reliability and programming efficiency without the need to uniformly raise voltages
3Productivity
If voltage is raised to improve hot electron injection, then programming efficiency is improved, but punch-through in unselected cells occurs
Solution Approach 1:
The patent creates different voltage conditions in different parts of the memory structure. The first S/D region receives a first voltage, the shared second S/D region receives an intermediate second voltage, and the third S/D region receives a third voltage. This localized voltage differentiation enables strong electric fields in selected cells for efficient hot carrier injection while maintaining weaker fields in unselected cells to prevent punch-through, thus resolving the contradiction between programming efficiency and reliability
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 programming efficiency by ensuring efficient hot carrier injection into the charge storage layer while preventing punch-through in unselected cells, thereby improving the overall performance of non-volatile memory devices.
Implementation Method 1
a first voltage is applied to the first S/D region, a second voltage to the second S/D region and a third voltage to the third S/D region. The second voltage is between the first and the third voltages, and the first to third voltages make carriers flow from the third S/D region to the first one and cause hot carriers in the channel of the first cell to be injected
Data Source
AI summary
A method of programming a first cell in a memory, wherein the first cell has a first S/D region and shares a second S/D region with a second cell that has a third S/D region opposite to the second S/D region. The channels of the first and the second cells are turned on, a first voltage is applied to the first S/D region, a second voltage is applied to the second S/D region and a third voltage is applied to the third S/D region. The second voltage is between the first voltage and the third voltage, and the first to third voltages make carriers flow from the third S/D region to the first S/D region and cause hot carriers in the channel of the first cell to be injected into the charge storage layer of the first cell.