Flash Memory Coupling Program Control for Read Margin

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Solution Overview

Problem

In MLC flash memory devices, maintaining the read margin between program states is challenging due to variations in threshold voltages during programming, which can lead to data read errors and reduced reliability.

Innovation Solution

A flash memory device with a coupling program control unit that verifies the programming of a first memory cell using a verification voltage and adjusts the programming of a second memory cell accordingly, ensuring that the first memory cell meets the desired data pattern before terminating programming, thereby reducing threshold voltage variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If programming is performed on MLC flash memory cells to store multi-bit data, then storage capacity increases, but threshold voltage variations increase causing read errors

Engineering Contradiction:

Improvestorage capacityVSAvoidread margin

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies preliminary action by performing verification operations during the programming process itself. Before programming completes, the system verifies the threshold voltage distribution of previously programmed cells to predict and prevent read errors in currently programming cells, allowing corrective actions to be taken in advance

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback by continuously monitoring the threshold voltage distribution of programmed memory cells and using this information to adjust programming parameters. The verification operation provides real-time feedback on programming quality, enabling dynamic adjustment of program voltages and timing to maintain read margins

Inventive Principle:

Principle #23Feedback

2Reliability

If verification operations are performed during programming to ensure data accuracy, then reliability improves, but programming time increases

Engineering Contradiction:

Improvedata accuracyVSAvoidprogramming time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The verification operation is performed as a preliminary check during the programming process rather than as a separate post-programming step. By verifying threshold voltage distribution in real-time during programming, the system can immediately correct issues without adding significant time overhead after programming completes

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent maintains continuity of useful action by integrating verification operations within the programming sequence itself. The verification and correction processes occur concurrently with or immediately during programming operations, eliminating idle time between programming steps and keeping the memory cells in constant productive state

Inventive Principle:

Principle #20Continuity of useful action

Data Source

PatentUS9257185B2Nonvolatile memory device, nonvolatile memory system, program method thereof, and operation method of controller controlling the same

Publication Date: 2016.02.09 SAMSUNG ELECTRONICS CO LTD

AI summary

According to example embodiments, a nonvolatile memory device includes a first memory cell configured to store a first data pattern, a second memory cell configured to be programmed using a program voltage, and a coupling program control unit. The coupling program control unit may be configured to perform a verification operation for verifying whether the first memory cell is programmed with the first data pattern. The verification operation may provide to the first memory cell a verification voltage corresponding to the first data pattern. The coupling program control unit may be configured to end programming the second memory cell when the verification operation on the first memory cell indicates a pass.