Foggy-Fine Memory Programming to Reduce Adjacent Cell Disturb
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Solution Overview
Problem
Memory devices experience program disturb during foggy-fine program operations, affecting the threshold voltage distribution of adjacent memory cells, which complicates the programming process and increases the time required for programming.
Innovation Solution
A memory device and method that perform a foggy program operation on first memory cells using a first verify pass voltage, a foggy program operation on second memory cells using the same voltage, and a fine program operation on the first memory cells by decreasing the verify pass voltage applied to the second memory cells, thereby reducing program disturb and optimizing the programming process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a fine program operation is performed on selected memory cells, then the threshold voltage distribution becomes narrow, but program disturb is applied to adjacent memory cells
Solution Approach 1:
The patent segments the programming process into two distinct phases: foggy program operation and fine program operation. The foggy program operation first programs selected memory cells to intermediate threshold voltage states, creating a buffer zone. Then the fine program operation programs cells to final states. This segmentation prevents direct high-stress programming of adjacent cells, reducing program disturb while maintaining narrow threshold voltage distribution.
Solution Approach 2:
The foggy program operation serves as a preliminary action before the fine program operation. By first programming selected memory cells to intermediate states and programming adjacent cells to preventive states, the patent prepares the memory block to withstand the subsequent fine programming operation, thereby minimizing program disturb to adjacent cells during the precision programming phase.
2Manufacturing precision
If foggy-fine program operation is performed, then programming precision is improved, but programming time is increased
Solution Approach 1:
The patent implements periodic action through multiple programming loops that alternate between foggy program operations and fine program operations. Each loop performs a foggy program followed by a fine program, creating a rhythmic programming sequence. This periodic structure allows the system to achieve high precision threshold voltage distribution while managing total programming time through efficient loop optimization and early termination when verification passes.
Data Source
AI summary
Provided herein is a memory device for performing a foggy-fine program operation and a method of operating the memory device. The memory device includes a memory block including a plurality of memory cells, a peripheral circuit configured to perform a program operation on selected memory cells among the plurality of cells, and a control logic configured to control the program operation by the peripheral circuit. The control logic is configured to control the peripheral circuit to perform a foggy program operation on first memory cells coupled to a first word line, among the plurality of memory cells, perform a foggy program operation on second memory cells coupled to a second word line adjacent to the first word line, among the memory cells, and perform a fine program operation on the first memory cells by decreasing a verify pass voltage to be applied to the second word line.