MLC Programming via Segmented Voltage Pulses and Sensing Feedback
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Solution Overview
Problem
Multi-level cell (MLC) memory faces challenges in precisely controlling programming and erasing operations due to manufacturing differences and environmental factors, leading to variations in memory cell states and increased read errors, which affect memory density and the number of bits that can be represented.
Innovation Solution
A system comprising a controller, a program and erase voltage generation (PEVG) component, and a verification component that applies initial and subsequent voltage pulses to set MLCs to specific states, with sensing feedback compared to electrical characteristic thresholds to ensure accurate state designation, allowing for fine-tuning of operations based on individual cell characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single voltage pulse is applied to program MLC memory cells, then the programming operation is fast, but the precision of setting cells to specific states is insufficient due to manufacturing variations
Solution Approach 1:
The programming operation is segmented into multiple voltage pulses with different magnitudes. A first voltage pulse with a first magnitude is applied to program the MLC memory cell to a first state, and a second voltage pulse with a second magnitude is applied to program the same cell to a second state. This segmentation allows precise control over the final resistance state of the cell, resolving the contradiction between programming precision and operational complexity.
Solution Approach 2:
The patent changes the voltage magnitude parameter across different programming pulses. By applying voltage pulses with different magnitudes (first magnitude for first state, second magnitude for second state), the system can precisely control the resistance state of MLC cells despite manufacturing variations. This parameter change approach directly addresses the precision issue while maintaining manageable operational complexity through systematic pulse sequences.
2Quantity of substance
If MLC memory cells are programmed to multiple distinct states, then memory density increases, but sensing margin variations increase leading to more read errors
Solution Approach 1:
The patent applies preliminary programming actions using specific voltage pulse sequences to ensure MLC cells are accurately positioned in their intended resistance states before reading. By pre-programming cells with controlled voltage magnitudes and verifying their states, the system reduces sensing margin variations and minimizes read errors, thus improving reliability while maintaining high memory density.
Solution Approach 2:
The system incorporates feedback mechanisms to verify the state of MLC cells after programming. By sensing the resistance state of cells and comparing against expected values, the system can identify and correct cells that did not transition properly, thereby reducing read errors and improving overall reliability of high-density MLC memory operations.
3Productivity
If voltage pulses are applied to program MLC memory, then programming speed is improved, but power consumption increases
Solution Approach 1:
The patent applies partial voltage pulses rather than continuously high voltage. By using a first voltage pulse with a first magnitude for initial programming and a second voltage pulse with a second magnitude for state adjustment, the system achieves effective programming with reduced overall power consumption compared to continuously applying maximum voltage, thus balancing productivity and energy efficiency.
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
Improves the success rate, precision, and power efficiency of programming and erasing operations, narrowing sensing margins and increasing the number of bits that can be represented by MLC memory.
Implementation Method 1
resistive-switching memory cells can be configured to have multiple states with distinct resistance values
Implementation Method 2
receive sensing feedback in response to a sensing pulse applied to the MLC, compare the sensing feedback to threshold data representative of a first electrical characteristic threshold
Data Source
AI summary
Mechanisms or techniques for improving operations such as program or erase operations that are intended to set a state of one or more multi-level memory cells (MLC) to a selected or designated state. For example, a first voltage pulse can be applied to an MLC that is intended to set the MLC to a desired state. Thereafter, a sensing pulse can be applied to the MLC, and one or more suitable electrical characteristic (EC) such as resistance can be measured and reported. This measured EC can then be compared to thresholds that define the range of acceptable values for the EC in order for the MLC to be deemed to be in the selected state. If the measured EC is not within the suitable range threshold, then one or more additional voltage pulses can be applied in order to properly set the MLC to the designated state and these additional voltages pulses can have different characteristics than the first voltage pulse.