Read Compensation for Partially Programmed NAND Flash Blocks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In non-volatile semiconductor memory devices, such as NAND flash memory, electromagnetic coupling effects become significant as device dimensions shrink, leading to shifts in threshold voltage distributions during programming, which can result in detection margin loss during read operations in partially programmed blocks.
Innovation Solution
Implementing read compensation techniques that adjust read levels based on the programming status of neighboring pages to account for interference from later programmed pages, ensuring accurate data retrieval by compensating for shifts in threshold voltage distributions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If device dimensions are scaled down to increase storage capacity, then storage density is improved, but electromagnetic coupling effects increase causing threshold voltage shifts and detection margin loss
Solution Approach 1:
The patent applies preliminary action by performing read compensation before the actual read operation. The system determines which pages have been programmed and calculates compensation values in advance, then applies these corrections to the read levels before reading the target page. This prevents the threshold voltage shifts caused by electromagnetic coupling from affecting the detection margin during the actual read operation.
Solution Approach 2:
The patent changes the read level parameters dynamically based on the programming status of neighboring pages. By adjusting the read reference voltages according to which pages are programmed or unprogrammed, the system compensates for the electromagnetic coupling effects that cause threshold voltage shifts, thereby maintaining adequate detection margins despite device scaling.
2Reliability
If read compensation is applied to account for unprogrammed pages, then detection margin is maintained, but read operation complexity increases
Solution Approach 1:
The patent implements self-service by using the memory device's own programming status information to perform the compensation. The system determines which pages are programmed by checking the programming status of neighboring pages, and uses this information to automatically adjust the read levels. This eliminates the need for external calibration or complex compensation algorithms, as the memory device compensates for its own electromagnetic coupling effects using its own operational data.
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
The solution effectively mitigates the loss of detection margin by compensating for voltage shifts, ensuring reliable read operations in partially programmed blocks and maintaining data integrity.
Implementation Method 1
electromagnetic coupling effects in memory devices are becoming increasingly important as memory device dimensions are scaled down
Data Source
Figure 1A~2
Figure 3
Figure 4
AI summary
Read compensation for partially programmed blocks of non-volatile storage is provided. In partially programmed blocks, the threshold voltage distributions may be shifted down relative to their final positions. Upon receiving a request to read a page that is stored in a block, a determination may be made whether the block is partially programmed. If so, then a suitable compensation may be made when reading the requested page. This compensation may compensate for the non-volatile storage elements (or pages) in the block that have not yet been programmed. The amount of compensation may be based on the amount of interference that would be caused to the requested page by later programming of the other pages. The compensation may compensate for shifts in threshold voltage distributions of the requested page that would occur from later programming of other pages.