3D Non-Volatile Memory Cell With Series Selector Elements
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Solution Overview
Problem
Current non-volatile memory devices face challenges in reducing leakage currents and managing snapback currents, which affect the efficiency and reliability of memory operations, especially as process geometries shrink.
Innovation Solution
Incorporating a series connection of two selector elements with different leakage characteristics and switching times within each non-volatile memory cell, along with a capacitor to absorb snapback current, to optimize the current-voltage characteristics and reduce leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single selector element is used in the memory cell, then the device complexity is low, but the leakage current is high and snapback effects are significant
Solution Approach 1:
The single selector element is segmented into two series-connected selector elements with different leakage characteristics. This segmentation allows each element to contribute differently to the overall cell behavior, with one element providing low leakage and the other providing appropriate switching characteristics, thereby reducing total leakage current while managing snapback effects.
Solution Approach 2:
Different regions of the selector element chain are assigned different leakage characteristics. The first selector element has a first leakage current and the second selector element has a second leakage current, where their combination optimizes the overall cell performance. This local differentiation of properties allows simultaneous optimization of leakage control and switching behavior.
2Manufacturing precision
If process geometries are shrunk to reduce cost per bit, then the manufacturing precision is improved, but the leakage current increases and snapback effects worsen
Solution Approach 1:
The invention changes the electrical parameters of the selector elements by using series connection and selecting elements with different leakage characteristics. This parameter transformation allows the memory cell to maintain low leakage current even when physical dimensions are reduced, compensating for the increased leakage that typically accompanies scaled geometries.
3Speed
If faster switching elements are used, then the switching speed is improved, but the snapback current increases
Solution Approach 1:
The snapback current, which is typically a harmful effect, is converted into a beneficial feature by using a selector element with higher leakage current that provides snapback. This controlled snapback helps reduce the overall leakage current of the memory cell while maintaining fast switching speeds, transforming a traditionally negative effect into a positive contribution to cell performance.
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 configuration achieves low leakage currents and high read margins while minimizing snapback effects, enhancing the performance and reliability of non-volatile memory devices.
Implementation Method 1
a capacitor to absorb snapback current
Implementation Method 2
selector elements with different leakage characteristics and switching times
Data Source
AI summary
An apparatus is provided that includes a bit line above a substrate, a word line above the substrate, and a non-volatile memory cell between the bit line and the word line. The non-volatile memory cell includes a reversible resistance-switching memory element coupled in series with an isolation element. The isolation element includes a first selector element coupled in series with a second selector element.