3D NAND Word-Line Ramp Timing to Preserve Read Window Margins
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The increasing density of memory cells in NAND flash memory devices leads to reduced read window margins (RWM) due to programming disturbances, especially in 3D NAND flash memory, which affects the accuracy of data reading.
Innovation Solution
A programming method that applies programming voltages to a selected word line and adjacent word lines with different ramp timings in multiple phases, enhancing the channel potential and reducing programming disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If memory cell density is increased, then storage capacity is improved, but read window margin is reduced due to programming disturbances
Solution Approach 1:
The patent applies preliminary action by pre-charging adjacent word lines before the programming operation. The method includes applying a first pass voltage to a first word line and a second pass voltage to a second word line before the main programming pulse. This preliminary voltage application stabilizes the threshold voltage distributions of adjacent memory cells, preventing programming disturbances and maintaining read window margins even as memory cell density increases.
2Productivity
If programming voltage is applied to improve programming speed, then productivity is improved, but programming disturbance increases reducing read window margin
Solution Approach 1:
The patent segments the programming operation into multiple phases with different voltage applications. Instead of applying a single high programming voltage, the method divides the process into: (1) applying a first pass voltage to a first word line, (2) applying a second pass voltage to a second word line, and (3) applying the main programming pulse. This segmentation allows the system to achieve programming speed while minimizing programming disturbances to adjacent cells, thereby preserving read window margins.
3Measurement precision
If pass voltage is applied to adjacent word lines, then programming disturbance is reduced, but programming time increases
Solution Approach 1:
The patent employs periodic action by applying pass voltages to adjacent word lines in alternating sequences during the programming operation. The method applies voltage to the first word line, then to the second word line, creating a periodic voltage application pattern. This periodic action stabilizes threshold voltage distributions and reduces programming disturbances while maintaining efficient programming timing through structured voltage sequencing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method improves read window margins, ensuring accurate data reading by stabilizing the threshold voltage distributions and reducing programming time.
Implementation Method 1
applying a programming voltage on a selected word line; applying a first pass voltage on a first word line adjacent to the selected word line; and applying a second pass voltage on a second word line adjacent to the selected word line
Data Source
AI summary
Examples of the present application disclose a programming method for a memory device, a memory device and a memory system. The programming method includes: applying a programming voltage on a selected word line; applying a first pass voltage on a first word line adjacent to the selected word line; and applying a second pass voltage on a second word line adjacent to the selected word line, wherein the first pass voltage and the second pass voltage include at least two ramp phases, and the first pass voltage and the second pass voltage have different ramp timings in at least one ramp phase among other ramp phases after the first ramp phase, and the ramp timing is the timing when the voltage value starts to ramp up from a certain voltage value.