Nonvolatile Memory Programming Method Advancing Pass Voltage Activation
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Solution Overview
Problem
Conventional NAND flash memory devices face inefficiencies in pass voltage activation time and charge pump size due to shared word lines for program and program-inhibited cells, which affects self-boosting efficiency during programming operations.
Innovation Solution
A nonvolatile memory device and programming method that simultaneously execute an initial precharge operation and charge word-line signal lines to a pass voltage during the programming operation, using a block-selection enabling signal to apply the pass voltage to word lines, thereby advancing the pass voltage activation time and reducing the size of the charge pump.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single word line is shared by program cells and program-inhibited cells with conventional self-boosting schemes, then the memory device can prevent inadvertent programming of program-inhibited cells, but the pass voltage activation time is increased and the charge pump size must be larger
Solution Approach 1:
The patent segments the word line functionality by introducing separate select lines (first select line and second select line) that control different portions of the memory array independently. This allows program cells and program-inhibited cells to be selectively accessed without sharing the same word line activation path, thereby reducing pass voltage activation time while maintaining reliability through controlled isolation of cell types during programming operations.
Solution Approach 2:
The patent applies preliminary action by pre-charging or pre-positioning select lines and control signals before the actual programming operation begins. The first and second select lines are configured in advance to prevent inadvertent programming of program-inhibited cells, allowing the main programming operation to proceed faster without compromising reliability.
2Reliability
If conventional self-boosting schemes are used to protect program-inhibited cells, then inadvertent programming is prevented, but the charge pump size must be larger
Solution Approach 1:
The patent divides the control architecture into separate select lines and control paths for program cells and program-inhibited cells. This segmentation eliminates the need for large charge pumps required by conventional self-boosting schemes, as each cell type can be controlled independently with smaller, more efficient charge pumping circuits.
Solution Approach 2:
By pre-configuring select lines and control signals before programming operations, the patent reduces the burden on charge pumps. The preliminary setup of control paths allows charge pumps to operate at lower capacity while still maintaining reliable protection against inadvertent programming.
3Productivity
If word-line signal lines are charged to pass voltage during programming operation, then programming speed is improved, but the charging burden increases requiring larger charge pump
Solution Approach 1:
The patent segments the word line charging function by introducing separate first and second select lines that can be charged independently. This allows the charging operation to be distributed across multiple smaller charge pumps rather than requiring one large charge pump, thereby maintaining high programming speed while reducing individual charge pump size and total charging burden.
Solution Approach 2:
The patent applies preliminary charging or pre-positioning of select lines before the main programming operation. This preliminary action reduces the peak charging burden during programming, allowing smaller charge pumps to achieve the same programming speed by spreading the charging load over time.
Data Source
AI summary
Disclosed is a programming method for a nonvolatile memory device. The method includes; charging word-line signal lines to a pass voltage during a pass voltage charge operation, simultaneously executing an initial precharge operation for strings including program-inhibited cells during the pass voltage charge operation, and applying the pass voltage to word lines from the word-line signal lines in response to a block-selection enabling signal.