Semiconductor Memory Device Precharging Method for Disturbance Reduction
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Solution Overview
Problem
The reliability of semiconductor memory devices is compromised due to increasing disturbances between memory cells and cell strings as integration levels rise, leading to potential data loss and reduced performance.
Innovation Solution
A program method for semiconductor memory devices that involves precharging cell strings with a positive voltage through a common source line, followed by a program operation on selected memory cells, where bit lines are electrically connected after the positive voltage is blocked, ensuring effective precharging and reduced disturbance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If integration level of semiconductor memory device is increased to reduce interval between memory cells and cell strings, then device density is improved, but disturbance between memory cells and cell strings increases
Solution Approach 1:
The patent applies preliminary action by precharging cell strings to a first voltage level before the program operation. This preliminary voltage application ensures that memory cells start from a known state, reducing disturbances during the programming process and improving overall reliability while maintaining high device density
Solution Approach 2:
The patent changes voltage parameters dynamically during operation. Cell strings are precharged to a first voltage, then during program operation, word lines are raised to a second voltage higher than the first. This parameter change allows the system to maintain stability at high integration levels by using voltage thresholds to control cell states and reduce interference between adjacent cells
2Reliability
If precharge operation is performed before program operation, then reliability is improved, but operation time is increased
Solution Approach 1:
The precharge operation is performed as a preliminary action before program operation, applying voltage to cell strings in advance. This ensures data integrity by establishing stable initial conditions, though it does add some time overhead that is managed through efficient timing control
Solution Approach 2:
The patent maintains continuity of useful action by overlapping certain operations and using the precharged state directly in the subsequent program operation without unnecessary intermediate steps. The word line voltage is raised continuously from the first to second level, and bit line voltage is adjusted in a coordinated manner, minimizing idle time while ensuring reliability
Data Source
AI summary
The present invention relates to a semiconductor memory device and a program method thereof. The program method according to an embodiment of the present invention includes: precharging a plurality of cell strings by providing a positive voltage to the plurality of cell strings through a common source line; and performing a program operation on selected memory cells by applying a program pulse to the selected memory cells.