Nonvolatile Memory Device Maximizing Sensing Margin via 1T-nCell Structure
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Solution Overview
Problem
There is a demand for semiconductor memory devices that operate at high speed and low operation voltage, and existing magnetic memory devices face challenges in efficiently storing and retrieving data due to limitations in resistance variation based on magnetization directions.
Innovation Solution
A nonvolatile memory device is designed with a 1T-nCell structure, incorporating magnetic tunnel junction (MTJ) cells and a specific configuration of word lines, bit lines, and transistors to maximize sensing margin and reduce chip size, allowing for efficient data storage and retrieval by varying resistance based on magnetization directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If magnetic memory devices use resistance variation based on magnetization directions for data storage, then data can be stored nonvolatibly, but the sensing margin is limited and chip size cannot be reduced efficiently
Solution Approach 1:
The memory cell is segmented into true cells and complementary cells, each serving distinct functions. The complementary cell structure divides the sensing path into two separate paths (through true cell and through complementary cell), allowing differential sensing that amplifies the sensing margin while maintaining compact cell layout
Solution Approach 2:
The patent combines true cells and complementary cells into a unified cell structure sharing common bit lines and word lines. This merging allows simultaneous utilization of both cell types for enhanced sensing margin without proportionally increasing chip area, as multiple cells share the same interconnect resources
2Speed
If magnetic memory devices operate at high speed, then data retrieval is faster, but power consumption increases
Solution Approach 1:
The memory operation uses periodic voltage application to word lines and bit lines, with pre-charge phases followed by sensing phases. This periodic action allows the circuit to reset and prepare for each operation, enabling high-speed continuous operation while managing power consumption through controlled voltage application cycles
Solution Approach 2:
The patent introduces sense amplifiers as intermediary components between the memory cells and output circuits. These amplifiers efficiently convert the small resistance changes in MTJ cells into larger voltage signals, enabling high-speed data retrieval with reduced power consumption by minimizing the current required through the memory cells themselves
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 solution enables high-speed operation and low power consumption while maximizing sensing margin and reducing chip size, effectively addressing the limitations of existing magnetic memory devices.
Implementation Method 1
A resistance of the MTJ pattern may vary with magnetization directions of the two magnetic materials. For example, the MTJ pattern has the greatest resistance when magnetization directions of the two magnetic materials are anti-parallel to each other, and it has the smallest resistance when magnetization directions of the two magnetic materials are parallel to each other.
Data Source
AI summary
A nonvolatile memory device according to the inventive concepts performs a read operation from a true cell storing data and complementary cell storing complementary data, thereby increasing or maximizing sensing margin. Also, the nonvolatile memory device connects a plurality of true cell/complementary cells to a word line, thereby markedly reducing the size of a memory cell array.