Nonvolatile Memory Read Method Channel Length Compensation
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Solution Overview
Problem
Nonvolatile memory devices with three-dimensional array structures face challenges in maintaining consistent sensing properties across asymmetrically structured vertical strings due to varying channel lengths, leading to differences in electrical properties during sensing operations.
Innovation Solution
A read method and nonvolatile memory device design that selects a sensing manner based on the channel length between a selected vertical string and a common source line, adjusting bias voltages, develop time, and read pass voltages to compensate for channel length differences, ensuring consistent sensing operations across even and odd vertical strings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If vertical strings are arranged in a three-dimensional array structure, then storage capacity and integration density are improved, but channel length variation between even and odd vertical strings causes inconsistent sensing properties
Solution Approach 1:
The patent applies local quality by providing different read pass voltages to even and odd vertical strings based on their specific channel length characteristics. Even vertical strings receive a first read pass voltage while odd vertical strings receive a second read pass voltage, tailoring the sensing conditions to the local electrical properties of each string type.
Solution Approach 2:
The patent changes the electrical parameter (read pass voltage) according to the channel length variation. By adjusting the read pass voltage level based on whether the vertical string is even or odd, the system compensates for the inherent channel length differences and maintains consistent sensing performance across all strings.
2Reliability
If channel length differences are compensated by adjusting read pass voltages, then sensing consistency is improved, but device complexity increases
Solution Approach 1:
The patent segments the vertical strings into even and odd groups based on their channel length characteristics. This segmentation allows the control logic to apply different read pass voltages to each group, simplifying the compensation approach compared to individually controlling each string while still achieving sensing consistency.
Solution Approach 2:
The control logic is designed to universally handle both even and odd vertical strings by selecting appropriate read pass voltages based on the string type. This multi-functional approach allows a single control mechanism to address the channel length variation issue across the entire array without requiring separate dedicated circuits for each string.
Data Source
AI summary
According to example embodiments, a read method of a nonvolatile memory device includes Disclosed is a read method of a nonvolatile memory device which includes selecting one of a plurality of vertical strings in a nonvolatile memory device, judging a channel length between a common source line and a selected one of the plurality of vertical strings, selecting a sensing manner corresponding to the judged channel length, and performing a sensing operation according to the selected sensing manner. The plurality of vertical strings may extend in a direction perpendicular to a substrate of the nonvolatile memory device.