Flash Memory Multi-Page Program Method
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Solution Overview
Problem
Existing multi-bit flash memory devices require an initial read operation and multiple program loops, leading to increased disturbances and inefficiencies in programming operations.
Innovation Solution
A flash memory device with a sense amplifier and write driver circuit that performs a verify read operation during the program execution period, allowing for the simultaneous programming of multi-bit data without an initial read operation, using an incremental step pulse programming method to control threshold voltage distribution and adjust verify read operations based on program verify codes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an initial read operation is performed before programming, then the programming operation can be executed with correct data, but the number of program operations increases and disturbances are caused
Solution Approach 1:
The patent applies preliminary action by pre-loading the data to be programmed into the page buffer before the programming operation begins. This eliminates the need for an initial read operation during the programming sequence, as the data is already prepared and stored in the buffer ready for immediate programming, thus improving efficiency while maintaining reliability
Solution Approach 2:
The patent extracts and removes the initial read operation from the programming sequence. By separating this unnecessary read step from the main programming flow, the invention reduces the total number of operations and eliminates the disturbances caused by redundant read activities, directly addressing the contradiction between reliability and productivity
2Quantity of substance
If multiple program loops are executed to program multi-bit data, then multi-bit data can be stored on one cell, but the number of program operations increases and disturbances increase
Solution Approach 1:
The patent merges the programming of multiple data bits into a single programming operation by utilizing the multi-threshold voltage characteristics of the memory cell. Instead of executing separate program loops for each bit, the invention combines all bit programming into one unified operation, thereby maintaining full data storage capacity while dramatically improving programming speed and reducing disturbances
3Measurement precision
If verify read operations are performed frequently during programming, then programming accuracy is improved, but the number of program operations increases
Solution Approach 1:
The patent applies periodic action by performing verify read operations at specific, predetermined intervals during the programming process rather than continuously or excessively frequently. This periodic verification approach maintains sufficient programming accuracy to ensure correct data storage while minimizing the time lost to verification operations and reducing the total number of program loops required
Data Source
AI summary
A flash memory device is configured to store multi-bit data on one cell utilizing fewer program operations. The flash memory device includes a memory cell, a sense amplifier and a write driver circuit. The sense amplifier is connected to a word line and a bit line. The sense amplifier and write driver circuit store data bits to be programmed on the memory cell. The sense amplifier and write driver circuit drives the bit line through a program voltage during a program execution period when at least one bit from among the data bits to be programmed is a program data bit, and performs a verify read operation when a program verify code representing a verify read period corresponds to a state of the data bits to be programmed.