Memory Hole Mis-shape Mitigation via Adaptive Programming
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Solution Overview
Problem
Mis-shaped memory holes in semiconductor memory devices lead to irregular electric fields, causing issues such as undesired programming of memory cells, as the strength of the electric field varies due to the irregular shape, affecting the effectiveness of boosting voltages intended to prevent programming of unselected cells.
Innovation Solution
Adjusting program parameters such as program voltage step size, verify voltage gaps, and verify levels based on the severity of memory hole mis-shape to ensure accurate programming and prevent undesired programming, by determining the severity through threshold voltage counts in specific zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If boosting voltages are applied to unselected word lines to prevent undesired programming, then unselected memory cells are inhibited from programming, but mis-shaped memory holes cause irregular electric fields that reduce the effectiveness of these boosting voltages
Solution Approach 1:
The patent adjusts program parameters including program voltage step size, verify voltage gaps, and verify levels based on the severity of memory hole mis-shape. By dynamically changing these electrical parameters, the system compensates for the irregular electric fields caused by mis-shaped memory holes, ensuring reliable programming even when manufacturing precision varies.
Solution Approach 2:
The system determines the severity of memory hole mis-shape through threshold voltage counts in specific zones and uses this information to adjust subsequent programming operations. This feedback mechanism allows the system to adapt programming parameters based on actual device characteristics, improving programming accuracy despite manufacturing variations.
2Productivity
If program voltage step size is increased to speed up programming, then programming speed improves, but mis-shaped memory holes cause irregular electric fields that lead to undesired programming of unselected cells
Solution Approach 1:
The patent dynamically adjusts the program voltage step size based on the determined severity of memory hole mis-shape. For memory devices with severe mis-shape, smaller step sizes are used to maintain programming control accuracy, while devices with better shape uniformity can utilize larger step sizes for faster programming. This adaptive parameter adjustment resolves the contradiction between speed and control accuracy.
3Measurement precision
If verify voltage gaps are reduced to improve programming precision, then programming accuracy improves, but programming time increases due to additional verify steps
Solution Approach 1:
The patent adjusts verify voltage gaps and verify levels based on the severity of memory hole mis-shape. By optimizing these verification parameters according to actual device characteristics, the system achieves high programming precision without unnecessarily increasing the number of verify steps, thus balancing accuracy and programming time.
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 allows for reliable programming of memory cells by tailoring program parameters to the severity of mis-shape, improving performance and preventing errors by ensuring uniform electric fields and effective inhibition of unselected memory cells.
Implementation Method 1
the strength of the electric field varies due to the irregular shape, affecting the effectiveness of boosting voltages intended to prevent programming of unselected cells
Data Source
AI summary
Techniques are provided for mitigating issues of memory hole mis-shape. In one aspect, one or more control circuits are configured to program a group of non-volatile memory cells from an erase state to a plurality of programmed states using a first program parameter. The one or more control circuits measure threshold voltages of the group to determine a severity of memory hole mis-shape in the group. The one or more control circuits program the group from the erase state to the plurality of programmed states using a second program parameter selected based on the severity of the memory hole mis-shape in the group.