Adaptive Voltage Setting for Non-Volatile Memory Threshold Distribution
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Solution Overview
Problem
Existing non-volatile semiconductor memory devices, such as EEPROM and flash memory, face inefficiencies due to the use of fixed programming, verifying, and reading voltages that do not account for variations in threshold voltage distribution, leading to non-optimized performance and potential errors.
Innovation Solution
A method is introduced to measure and customize voltage levels for write, read, and verify operations based on the threshold voltage distribution of multi-level storage elements, allowing for optimized performance by adapting voltage settings to specific conditions within each memory device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed programming, verifying, and reading voltages are used in non-volatile memory devices, then the device operation is simplified and manufacturing is easier, but the performance is non-optimized and errors may occur due to threshold voltage distribution variations
Solution Approach 1:
The patent measures threshold voltage distributions and determines optimized voltage levels for programming, verifying, and reading operations before actual data operations. These pre-determined voltage levels are stored in lookup tables, allowing the system to quickly retrieve and apply optimal voltages without real-time calculation, thus improving reliability while maintaining operational simplicity
Solution Approach 2:
The patent dynamically adjusts voltage parameters (programming voltage VPGM, verify voltage VV, read voltage VR) based on measured threshold voltage distributions. By changing these voltage parameters according to actual device characteristics rather than using fixed values, the system achieves optimized performance and reduced errors
2Reliability
If customized voltage levels are determined and stored for each set of non-volatile storage elements, then the reliability and performance are enhanced, but the manufacturing process and device configuration become more complex
Solution Approach 1:
The patent implements self-service by having the memory device automatically measure its own threshold voltage distributions and determine its own optimized voltage levels during initialization or manufacturing testing. The device stores these self-determined parameters in its internal lookup tables, eliminating the need for external manual configuration and simplifying the manufacturing process despite the customization
Solution Approach 2:
The optimized voltage levels are determined and stored in lookup tables during manufacturing or initial device setup, before the device enters normal operation. This preliminary configuration allows the device to automatically use optimized voltages without requiring complex real-time adjustments during manufacturing, thus enhancing reliability while maintaining ease of manufacture
Data Source
AI summary
A method in which non-volatile memory device is accessed using voltages which are customized to the device, and/or to portions of the device, such as blocks or word lines of non-volatile storage elements. The accessing can include programming, verifying or reading. By customizing the voltages, performance can be optimized, including addressing changes in threshold voltage which are caused by program disturb. In one approach, different sets of storage elements in a memory device are programmed with random test data. A threshold voltage distribution is determined for the different sets of storage elements. A set of voltages is determined based on the threshold voltage distribution, and stored in a non-volatile storage location for subsequent use in accessing the different sets of storage elements. The set of voltages may be determined at the time of manufacture for subsequent use in accessing data by the end user.