Nonvolatile Memory Sense Signal Voltage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Nonvolatile memory devices face interference phenomena due to shifts in threshold voltages of adjacent memory cells, particularly in multi-level cell programming methods, leading to malfunctions caused by narrowed voltage margins.
Innovation Solution
A nonvolatile memory device and programming method that select and use specific sense signals based on data to be programmed into adjacent memory cells, performing program verification operations with voltage levels adjusted for each cell to prevent over-programming and ensure accurate data storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a multi-level cell program method is used to increase storage capacity, then data storage density is improved, but interference phenomena between adjacent memory cells increases due to narrowed threshold voltage margins
Solution Approach 1:
The patent applies local quality by selecting different sense signal voltage levels based on the specific data patterns of adjacent memory cells. Instead of using a uniform sense signal for all cells, the system adjusts the sense signal characteristics locally for each cell based on its adjacent cells' data states, thereby compensating for interference phenomena while maintaining high storage density
Solution Approach 2:
The patent changes the voltage level parameter of the sense signal dynamically based on the data to be programmed in adjacent memory cells. By adjusting the sense signal voltage level (e.g., selecting between different voltage levels such as Vss, Vread1, Vread2), the system compensates for threshold voltage shifts caused by interference, enabling accurate verification even in MLC mode with narrowed margins
2Measurement precision
If sense signal voltage level is increased to improve verification accuracy, then measurement precision is improved, but risk of over-programming increases due to higher voltage impact on memory cells
Solution Approach 1:
The patent implements dynamics by making the sense signal voltage level adjustable and adaptive rather than fixed. The sense signal generation circuit dynamically selects appropriate voltage levels based on real-time conditions including adjacent cell data patterns and verification requirements, allowing optimal balance between verification accuracy and preventing over-programming
Solution Approach 2:
The patent uses feedback by performing iterative verification operations where the result of each verification influences the selection of sense signal voltage level for subsequent operations. The system monitors verification outcomes and adjusts sense signal parameters accordingly, enabling accurate detection while preventing excessive programming through adaptive control
3Device complexity
If program verification is performed with fixed sense signal voltage levels, then device complexity is reduced, but manufacturing precision deteriorates due to inability to compensate for threshold voltage shifts
Solution Approach 1:
The patent applies preliminary action by determining the appropriate sense signal voltage level before performing the program verification operation. The system analyzes the data to be programmed in adjacent cells in advance and pre-selects the optimal sense signal level, ensuring accurate verification without requiring complex real-time adjustments during the verification process
Solution Approach 2:
The patent achieves universality by designing a sense signal generation circuit that can output multiple voltage levels using the same hardware structure. The circuit selectively provides different sense signal levels (Vss, Vread1, Vread2, etc.) based on control signals, enabling precise verification for different data patterns without requiring separate dedicated circuits for each voltage level
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 method effectively reduces interference by controlling sense signal voltage levels or timing, preventing over-programming and ensuring accurate threshold voltage settings, thereby enhancing data integrity and reliability in nonvolatile memory devices.
Implementation Method 1
a sense signal generation circuit coupled to the page buffers and configured to generate the plurality of sense signals having different voltage levels for the program verification operation
Implementation Method 2
electrons within a thin oxide layer, e.g., about 100 Å in thickness, are moved by a strong electric field supplied to the oxide layer, thereby shifting the threshold voltages of the memory cell
Data Source
AI summary
A programming method of a nonvolatile memory device includes inputting even data and odd data to be programmed into even memory cells coupled to even bit lines and odd memory cells coupled to odd bit lines, respectively, setting a sense signal as a first sense signal or a second sense signal having a lower voltage level than the first sense signal, based on odd data of odd memory cells adjacent to each of the even memory cells to be programmed, programming the even data into the even memory cells by supplying a program voltage, performing a program verify operation on each of the even memory cells in response to the set sense signal, and programming the odd data into the odd memory cells by supplying a program voltage.