Memory Controller Multi-Stage Write Timing
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Solution Overview
Problem
Current memory systems face challenges in reducing write time while maintaining reliability, particularly due to the risk of data deterioration associated with the accumulation of electrons in charge storage films during multi-bit write operations.
Innovation Solution
The memory system employs a controller that executes write operations in a two-stage manner, with an initial MLC write operation followed by a Fine write operation, using internal data if the time elapsed since the MLC write is short and external data if it exceeds a threshold, to minimize data fluctuation and ensure reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If multi-bit data is written in a single write operation, then write time is reduced, but data reliability deteriorates due to electron accumulation in charge storage films
Solution Approach 1:
The patent divides a multi-bit write operation into multiple sequential stages: first performing an MLC write operation to write initial data, then performing a Fine write operation to write additional data bits. This segmentation prevents excessive electron accumulation in the charge storage film while still achieving multi-bit data storage, thereby resolving the contradiction between reduced write time and maintained data reliability.
2Productivity
If MLC write operation is performed first, then write speed is improved, but electron accumulation increases causing data deterioration
Solution Approach 1:
The patent extracts and separates the write operation into two distinct phases: the MLC write operation that writes the first part of multi-bit data, and the Fine write operation that writes the remaining data bits. By taking out the electron accumulation problem and addressing it through sequential operations with appropriate timing, the system maintains high write speed while preventing harmful electron accumulation that would otherwise deteriorate data integrity.
3Reliability
If write operation is performed in multiple stages, then data reliability is maintained, but write time increases
Solution Approach 1:
The patent implements preliminary action by first performing the MLC write operation to establish initial data in the charge storage film, then subsequently performing the Fine write operation to complete the multi-bit data storage. This preliminary action approach allows the system to maintain data reliability through controlled electron accumulation while minimizing total write time by optimizing the sequence and timing of operations, rather than using slower alternative methods.
Data Source
AI summary
A memory system includes a nonvolatile memory including a memory cell, and a controller. The controller is configured to write multi-bit data into the memory cell through a first write operation of writing a first part, and not a second part, of the multi-bit data and then a second write operation of writing the first and second parts. The controller is configured to, during writing of the multi-bit data, determine an amount of time that has passed since the first write operation, perform the second write operation in a first manner by inputting the second part, and not the first part, from the controller, when the determined amount is less than a threshold amount, and perform the second write operation in a second manner by inputting the first and second parts from the controller, when the determined amount is greater than the threshold amount.