Non-Volatile Memory Read Method Preventing Hot Carrier Injection
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Solution Overview
Problem
The read disturbance phenomenon occurs in non-volatile memory devices due to the hot carrier injection phenomenon, which changes the threshold voltage of adjacent memory cells during the read operation, causing data integrity issues.
Innovation Solution
The method involves discharging bit lines to a low level, applying a read voltage or pass voltage to the word line, precharging the bit line coupled to the memory cell to be read to a high level, evaluating the voltage level, and sensing data based on the evaluated voltage, while ensuring the drain and source selecting signals are high to prevent hot carrier injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a read voltage is applied to a word line during read operation, then data can be read from the memory cell, but hot carrier injection occurs to adjacent memory cells causing read disturbance
Solution Approach 1:
The bit line is precharged to a high level before the read voltage is applied to the word line. This preliminary action ensures that when the read operation occurs, the bit line is already in the correct state, allowing the read voltage to be applied without causing hot carrier injection to adjacent cells. The precharging step prepares the system in advance to avoid the harmful effect during the actual read operation.
2Ease of operation
If different voltages are applied to bit lines connected and not connected to the cell string, then read operation can be performed, but threshold voltage of peripheral memory cells changes causing read disturbance
Solution Approach 1:
The patent applies different voltage treatments to different bit lines based on their connection status to the selected memory cell. The bit line connected to the cell string is precharged to high level, while the bit line not connected to the cell string receives a different voltage level. This local differentiation ensures that only the necessary bit line is actively involved in the read operation, preventing unwanted voltage effects on peripheral memory cells and maintaining threshold voltage stability.
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 effectively prevents the hot carrier injection phenomenon, maintaining the threshold voltage of peripheral memory cells and thus preventing read disturbances during data reading operations.
Implementation Method 1
a hot carrier injection phenomenon can occur to a second memory cell adjacent to the first memory cell
Data Source
AI summary
A method of reading data in a non-volatile memory device includes providing a plurality of blocks and a plurality of bit lines, each block having a plurality of memory cells, each block coupled to at least one bit line. First and second bit lines are discharged to be at a low level, the first bit line coupled to a first block, the second bit line coupled to a second block. A read voltage is applied to a first word line coupled to a memory cell to be read in the first block. A pass voltage is applied to a second word line coupled to a memory cell not to be read in the first block. The first bit line coupled to the memory cell to be read is precharged to a high level after applying the read voltage to the first word line and the pass voltage to the second word line. A voltage level of the first bit line is evaluated. Data stored in the memory cell to be read is sensed in accordance with the evaluated voltage level of the first bit line.