Multi-bit Flash Memory Program Voltage Adjustment for Skipped Bits
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Solution Overview
Problem
Current flash memory devices face challenges in efficiently programming and reading multi-bit data in a single memory cell, particularly when previous bit programs are skipped, leading to potential program errors and undesired program state transitions.
Innovation Solution
The implementation of a method where the program and read conditions for a flash memory device are adjusted based on whether the previous bit program is skipped or not, using flag information to verify program states and adjust program voltages accordingly, ensuring accurate program state transitions and read operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multi-bit data is programmed in a single memory cell, then storage capacity is improved, but program reliability deteriorates when previous bit programs are skipped
Solution Approach 1:
The patent applies preliminary action by performing a read operation before programming to detect the current program state of the memory cell. Based on this detection, the system determines whether previous bit programs were skipped and adjusts the program voltage accordingly. This preliminary detection prevents program reliability issues by preparing the appropriate programming conditions in advance, resolving the contradiction between high storage capacity and reliable programming.
2Manufacturing precision
If program condition is adjusted based on previous bit program status, then program accuracy is improved, but device complexity increases
Solution Approach 1:
The patent implements feedback by reading the current program state of the memory cell before programming and using this information to adjust the program voltage for subsequent bits. The system continuously monitors the program state and modifies programming conditions based on this feedback, ensuring accurate program transitions while managing complexity through intelligent control rather than hardware complexity.
3Measurement precision
If read voltage is adjusted according to program skip status, then read accuracy is improved, but operation complexity increases
Solution Approach 1:
The patent applies dynamics by making the read voltage adaptive rather than fixed. The system dynamically adjusts the read voltage based on the detected program state and whether previous bits were skipped. This dynamic adjustment ensures accurate reading of multi-bit data under varying programming conditions while the control circuit manages the complexity of voltage adjustment automatically.
Data Source
AI summary
The flash memory device of the present invention is configured to program a plurality of bits per unit cell, wherein a program condition of a selected bit is set according to whether a program for the most previous bit to the selected bit for programming is skipped or not skipped. As a result, an accurate programming and reading operation is possible even in case a program for a middle bit is skipped.