Nonvolatile Memory Read Voltage Adjustment via Adjacent Word-Line
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Solution Overview
Problem
Nonvolatile semiconductor memory devices, such as flash memory, face performance issues due to adjacent word-line coupling during read operations, which affects the accuracy and speed of data retrieval.
Innovation Solution
A method and device for reading data in nonvolatile memory devices that involves performing a read operation on a first word-line by adjusting the recover read voltage based on the program state and operating parameters derived from an adjacent word-line, using a control circuit to generate control signals for the voltage generator and page buffer circuit, thereby minimizing word-line coupling effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a read operation is performed on a first word-line in a nonvolatile memory device, then data retrieval speed is improved, but adjacent word-line coupling causes read errors and reduces data accuracy
Solution Approach 1:
The patent applies preliminary action by performing a read operation on an adjacent second word-line before reading the first word-line. This preliminary read operation allows the system to detect the program state of the adjacent word-line, which is then used to adjust the recover read voltage for the first word-line, thereby preventing coupling-induced read errors before they occur.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting the recover read voltage level based on the program state of the adjacent word-line. The control circuit modifies the voltage parameter (recover read voltage) according to the detected program state, which compensates for the coupling effect and maintains accurate data reading despite the presence of adjacent word-line interference.
2Measurement precision
If the recover read voltage level is adjusted based on adjacent word-line program state, then read accuracy is improved, but device complexity increases due to additional control circuit requirements
Solution Approach 1:
The control circuit is designed to perform multiple functions: it controls the voltage generator for normal read operations, detects the program state of adjacent word-lines, determines the appropriate recover read voltage level, and adjusts the voltage accordingly. By making the control circuit multi-functional, the patent avoids adding separate dedicated circuits for each function, thereby limiting the increase in device complexity while achieving improved read accuracy.
Solution Approach 2:
The patent implements a feedback mechanism where the control circuit reads data from the adjacent second word-line, determines its program state, and uses this information to adjust the recover read voltage applied to the first word-line. This feedback loop enables automatic adaptation to coupling conditions without requiring complex external control or multiple independent circuits.
3Reliability
If a read operation is performed on an adjacent second word-line before the first word-line, then coupling effects are reduced and read accuracy is improved, but read operation time increases
Solution Approach 1:
The patent applies partial action by performing a read operation on only one adjacent second word-line (either the upper or lower adjacent word-line) rather than both adjacent word-lines. This selective approach provides sufficient information to adjust the recover read voltage for the first word-line while minimizing the additional time required, as reading from a single adjacent word-line is faster than reading from both.
Data Source
AI summary
In a method of reading data in a nonvolatile memory device including a plurality of memory cells arranged at intersections of a plurality of word-lines and a plurality of bit-lines, a read request on a first word-line of the plurality of word-lines is received, a read operation is performed on a second word-line adjacent to the first word-line and a read operation is performed on the first word-line based on data read from memory cells of the second word-line. The read operation on the first word-line is performed by adjusting a level of recover read voltage applied to the first word-line during the read operation of the first word-line based on at least one of a program state of the data read from memory cells of the second word-line and an operating parameter of the nonvolatile memory device.