Multilevel Cell Memory Programming via Segmented SLC-MLC Blocks

Solution Overview

Problem

Multi-level cell (MLC) nonvolatile memory systems face challenges in programming efficiency due to increased precision requirements and potential charge shifts between adjacent cells, leading to slower data storage and compatibility issues with different memory standards.

Innovation Solution

A method involving a two-block system where a first block with two memory states is used for initial data storage, and a second block with more than two memory states is partially programmed in parallel, with subsequent further programming based on data from the first block to achieve all memory states, optimizing storage density and speed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If MLC format is used for data storage, then storage density is improved, but programming speed deteriorates due to increased precision requirements and charge shift compensation needs

Engineering Contradiction:

Improvestorage densityVSAvoidprogramming speed

Core Design Contradiction:

Quantity of substanceVSProductivity

Solution Approach 1:

The memory system is divided into two separate blocks: a first block configured for SLC operation (two memory states) and a second block configured for MLC operation (more than two memory states). This segmentation allows independent optimization of each block for its specific function, enabling parallel operation to achieve both high storage density and fast programming speed.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Data is first preliminarily stored in the first block (SLC) at high speed, then subsequently programmed into the second block (MLC) for high-density storage. The first block serves as a temporary high-speed buffer that enables fast initial data capture before the slower MLC programming completes.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If SLC format is used for data storage, then programming speed is improved, but storage density deteriorates

Engineering Contradiction:

Improveprogramming speedVSAvoidstorage density

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The memory system is divided into two separate blocks: a first block configured for SLC operation (two memory states) and a second block configured for MLC operation (more than two memory states). This segmentation allows independent optimization of each block for its specific function, enabling parallel operation to achieve both high storage density and fast programming speed.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Data is first preliminarily stored in the first block (SLC) at high speed, then subsequently programmed into the second block (MLC) for high-density storage. The first block serves as a temporary high-speed buffer that enables fast initial data capture before the slower MLC programming completes.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If parallel programming is performed in both blocks, then storage efficiency is improved, but charge shift interference between adjacent cells increases

Engineering Contradiction:

Improvestorage efficiencyVSAvoidcharge shift interference

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The memory system is divided into two separate blocks: a first block configured for SLC operation (two memory states) and a second block configured for MLC operation (more than two memory states). This segmentation allows independent optimization of each block for its specific function, enabling parallel operation to achieve both high storage density and fast programming speed.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different blocks are assigned different operational characteristics: the first block uses simpler two-state programming with less charge shift sensitivity, while the second block uses multi-state programming with more precise charge control. Each block's programming parameters are locally optimized for its specific memory cell type.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS7630252B2Systems for programming multilevel cell nonvolatile memory

Publication Date: 2009.12.08 SANDISK TECHNOLOGIES LLC

AI summary

A memory system includes a first block in which data is stored with a low density and a second block in which data is stored with a high density. When data is received it is written to the first block, and in parallel some of the data is written to the second block, so that the second block is partially programmed. The second block is later fully programmed by copying additional data from the first block.