QLC Memory Programming With Separate Sense Times for Vt Width Control
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Solution Overview
Problem
Existing semiconductor memory technologies face issues with Vt width degradation and inefficiencies in programming operations, particularly in quad level cell (QLC) programming, due to the use of a single constant sense time for both foggy and fine programming operations.
Innovation Solution
Implementing different sense times for foggy and fine programming operations, and varying sense times for different states within the foggy-fine programming process, specifically using a quad level cell (QLC) programming operation with distinct sense times in multiple programming passes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single constant sense time is used for both foggy and fine programming operations, then the programming operation can be simplified and executed faster, but Vt width degradation occurs and programming precision deteriorates
Solution Approach 1:
The patent applies dynamics by transitioning from a static, constant sense time to a dynamic, variable sense time that adapts to different programming stages. The sense time is adjusted based on the specific programming phase (foggy or fine) and the programmed state of memory cells, allowing the system to optimize both speed and precision at different moments in the programming process.
Solution Approach 2:
The patent changes the sense time parameter throughout the programming operation. Different sense time values are selected based on the programming stage and memory cell state, enabling the system to achieve optimal Vt width control during fine programming while maintaining efficient programming speed during foggy programming stages.
2Manufacturing precision
If different sense times are used for foggy and fine programming operations, then Vt width degradation is reduced and programming precision is improved, but the programming operation becomes more complex
Solution Approach 1:
The patent segments the programming operation into distinct phases (foggy programming and fine programming), each with its own optimized sense time parameters. This segmentation allows the system to apply different sense time values appropriate for each stage, improving Vt width control while managing complexity through structured phase division.
Solution Approach 2:
The system dynamically selects sense time values based on the current programming phase and memory cell state, transitioning between different sense time configurations as needed. This dynamic approach enables precise Vt width control during fine programming while maintaining the benefits of optimized sensing during foggy programming.
3Manufacturing precision
If varying sense times are used for different programmed states within foggy-fine programming, then programming precision and Vt width control are further improved, but the operation time increases
Solution Approach 1:
The patent changes sense time parameters based on the programmed state of memory cells during foggy-fine programming operations. By selecting appropriate sense time values for different states, the system achieves improved programming precision while managing the time overhead through state-aware parameter selection.
Solution Approach 2:
The patent replaces a uniform, mechanical sense time approach with a state-dependent, adaptive sense time selection mechanism. This substitution enables the system to optimize precision for each programmed state while minimizing time loss through intelligent parameter selection rather than exhaustive measurement.
Data Source
AI summary
A memory device includes a plurality of memory cells and control circuitry configured to perform a foggy-fine programming operation in which memory cells are programmed in multiple programming passes. To perform the foggy-fine programming operation, the control circuity is configured to perform a first pass of the foggy-fine programming operation on the memory cells, perform, in accordance with a first sense time, a first sensing operation on the memory cells programmed in the first pass of the foggy-fine programming operation, perform a second pass of the foggy-fine programming operation on the memory cells previously programmed in the first pass of the foggy-fine programming operation, and perform, in accordance with a second sense time, a second sensing operation on the memory cells programmed in the first pass and the second pass of the foggy-fine programming operation, wherein the second sense time is different from the first sense time.