Flash Memory Soft Landing Programming Method
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for programming multilevel cells in flash memory devices are inefficient, requiring a large number of programming pulses and resulting in prolonged programming times while maintaining limited resolution.
Innovation Solution
Implementing two series of programming pulses with large program steps, where the first series increases the threshold voltage in larger increments (ΔVpgm) and the second series provides finer adjustments (ΔVt3) for a 'soft landing' to the final threshold voltage, reducing the total number of pulses needed and programming time without compromising accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional small increment programming pulses are used, then programming resolution is maintained, but programming time is prolonged and the number of pulses required is large
Solution Approach 1:
The patent divides the programming process into two distinct phases: a first phase using large increment pulses (ΔVpgm) to rapidly approach the target threshold voltage, and a second phase using small increment pulses (ΔVt3) to precisely reach the final target. This segmentation allows each phase to optimize for its specific function, resolving the contradiction between speed and precision
Solution Approach 2:
The first phase of programming using large increment pulses performs a preliminary action to bring the threshold voltage close to the target value before the second phase begins. This preliminary approach eliminates the need for numerous small pulses, significantly reducing total programming time while maintaining final precision
2Manufacturing precision
If large number of programming pulses are used, then desired threshold voltage is achieved, but programming efficiency is reduced
Solution Approach 1:
The patent dynamically adjusts the pulse increment size based on the programming stage. The pulse width and amplitude are not fixed but are modulated according to the cell's current threshold voltage state, allowing optimal performance across different programming phases and improving overall efficiency
Solution Approach 2:
The programming process uses periodic verification steps interspersed between programming pulses. After each pulse or set of pulses, the cell state is verified, and programming continues only if the target has not been reached. This periodic action prevents wasted pulses and improves efficiency
Data Source
AI summary
Methods of programming memory cells are disclosed. In at least one embodiment, programming is accomplished by applying a first set of programming pulses to program to an initial threshold voltage, and applying a second set of programming pulses to program to a final threshold voltage.