Nonvolatile Memory Multi-Step Programming Pulse Width Control
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Solution Overview
Problem
As semiconductor technology advances, multi-level cells (MLCs) in nonvolatile memory devices face challenges with reduced read margins due to decreasing memory cell sizes and interference between adjacent cells, leading to potential data loss.
Innovation Solution
A multi-step program scheme is implemented, where program operations with different pulse widths are used to program first and second page data into memory cells, adjusting pulse widths based on the type of operation and the number of threshold voltage states to improve programming efficiency and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multi-level cells (MLCs) are used to store at least two bits of data in a single memory cell, then storage density is improved, but read margin deteriorates
Solution Approach 1:
The patent applies parameter changes by using multiple program voltages with different pulse widths to program different pages of data into MLCs. The control unit adjusts the pulse width parameter based on the type of data being programmed (first page data uses a first pulse width, second page data uses a second pulse width), thereby optimizing the programming process for different data types and improving overall read margin while maintaining high storage density
2Productivity
If memory cell sizes are decreased with recent advance in semiconductor integration technology, then integration density is improved, but data retention reliability deteriorates due to external factors and interference between adjacent memory cells
Solution Approach 1:
The patent segments the programming process into multiple operations with different pulse widths. The control unit determines which programming operation to perform based on the data type, and applies corresponding pulse widths to program voltages. This segmentation allows optimized programming for different data types, reducing interference between adjacent cells and improving data retention reliability while maintaining high integration density
3Ease of operation
If a single program voltage pulse width is used for all data programming operations, then device operation is simplified, but programming efficiency and accuracy deteriorate
Solution Approach 1:
The patent introduces dynamics by making the pulse width parameter variable rather than fixed. The control unit dynamically adjusts the pulse width based on the type of data being programmed (first page data versus second page data). This dynamic adjustment optimizes programming efficiency and accuracy for different data types while maintaining relatively simple device operation through automated control
Data Source
AI summary
A program method of a nonvolatile memory device including a plurality of memory cells, each storing at least two bits of data, includes performing a first program operation based on a plurality of program voltages having a first pulse width to program first page data into selected memory cells connected to a selected word line among the plurality of memory cells; and performing a second program operation based on a plurality of program voltages having a second pulse width different from the first pulse width to program second page data into the selected memory cells in which the first page data is programmed.