Semiconductor Read Voltage Segmentation for Threshold Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor memory devices face challenges in improving the reliability of read operations, particularly in memory blocks where program operations are not fully completed, as existing methods can affect threshold voltages of unselected pages due to differing voltage applications.
Innovation Solution
A semiconductor device and method that apply a read voltage to a selected page and distinct pass voltages to programmed and non-programmed pages, with a first pass voltage applied to non-selected programmed pages and a second pass voltage lower than the first applied to non-selected non-programmed pages, to minimize changes in threshold voltage distribution and enhance read operation reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single pass voltage is applied to all non-selected pages during read operation, then the circuit design is simple, but the threshold voltage distribution becomes unstable due to channel current variations in memory blocks with incomplete program operations
Solution Approach 1:
The patent segments the non-selected pages into two distinct groups: programmed pages and non-programmed pages. Each group receives a different pass voltage level. This segmentation allows the system to address the threshold voltage instability issue by applying appropriate voltages to each group, thereby improving read operation reliability without requiring complete redesign of the voltage application mechanism.
Solution Approach 2:
The patent applies different pass voltage levels to different groups of pages based on their program operation status. Specifically, a first pass voltage is applied to non-selected programmed pages while a second pass voltage is applied to non-selected non-programmed pages. This local differentiation in voltage application stabilizes the threshold voltage distribution in memory blocks where program operations are not completed, thereby improving read reliability.
2Reliability
If different pass voltages are applied to programmed and non-programmed pages, then the threshold voltage distribution is stabilized, but the voltage control complexity increases
Solution Approach 1:
The patent performs preliminary classification of pages into programmed and non-programmed groups before applying different pass voltages during the read operation. By determining the program operation status in advance and preparing the appropriate voltage levels beforehand, the system can smoothly transition to differentiated voltage application without requiring complex real-time decision-making circuits, thus managing voltage control complexity more effectively.
Solution Approach 2:
The patent changes the voltage parameter (pass voltage level) based on the program operation status of different page groups. By adjusting the voltage parameter to have two distinct levels (first pass voltage for programmed pages, second pass voltage for non-programmed pages), the system stabilizes the threshold voltage distribution while maintaining manageable voltage control through parameter differentiation rather than complex control logic.
Data Source
AI summary
The semiconductor device includes a memory block including programmed pages and non-programmed pages, a peripheral circuit configured to perform a read operation of the memory block, and a control circuit configured to control the peripheral circuit so that a read voltage is applied to a word line coupled to a selected page among the pages for the read operation, a first pass voltage is applied to word lines coupled to the programmed pages among pages that are not selected for the read operation, and a second pass voltage lower than the first pass voltage is applied to word lines coupled to non-programmed pages among the pages that are not selected for the read operation.