Nonvolatile Memory Channel Boosting via Adjacent Word Line Precharge
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Solution Overview
Problem
Nonvolatile memory devices face challenges in minimizing program disturbance during programming operations due to inefficient channel boosting, particularly in NAND flash memories, where initial charge transfer is limited to programmed cells, leading to potential misprogramming of program-inhibited cells.
Innovation Solution
The method involves precharging bit lines based on loaded data, boosting channels by supplying an initializing voltage to word lines adjacent to the selected word line during the bit line set-up interval, which enhances channel boosting efficiency and reduces program disturbance by ensuring initial charge transfer to both programmed and program-inhibited cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If initial charge transfer is limited to programmed cells during programming operation, then programming operation can be performed, but channel boosting is inefficient and program disturbance occurs in program-inhibited cells
Solution Approach 1:
The patent applies preliminary action by performing initial charge transfer to all memory cells (including program-inhibited cells) before the actual programming operation. This preliminary boosting of channels ensures that when programming is performed, the channels are already in an optimized state, preventing program disturbance in program-inhibited cells while maintaining programming accuracy.
2Reliability
If channel boosting is performed efficiently for all cells, then program disturbance is reduced, but additional operations are required during bit line set-up interval
Solution Approach 1:
The patent merges the initial charge transfer operation with the bit line set-up interval, combining two operations that occur in the same time period. By performing channel boosting for all memory cells during the bit line set-up interval (when bit lines are being prepared for programming), the patent avoids adding separate operations and maintains operational efficiency while improving programming reliability.
3Productivity
If initializing voltage is supplied to all word lines including adjacent word lines, then channel boosting efficiency is enhanced, but voltage supply scope is expanded
Solution Approach 1:
The patent applies local quality by selectively supplying initializing voltage to specific word lines based on their function. String selection lines and ground selection lines receive initializing voltage to enable proper channel formation and boosting, while other word lines receive different voltages appropriate for their specific roles during programming. This targeted approach enhances channel boosting efficiency without unnecessarily expanding the voltage supply scope.
Data Source
AI summary
A programming method of a nonvolatile memory device includes precharging bit lines of the nonvolatile memory device based on loaded data, boosting channels corresponding to the respective precharged bit lines, after supplying word lines adjacent to a selected word line of the nonvolatile memory device with an initializing voltage, the selected word line is a word line selected for programming, and supplying a word line voltage for programming to the channels, after the channels are boosted.