Memory Programming Checkpoint Optimization
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Solution Overview
Problem
Existing memory devices face challenges in reducing program time while ensuring accurate programming of memory cells to their assigned threshold voltage levels, which is crucial for reliable data storage and retrieval, particularly in multi-pass programming operations.
Innovation Solution
The proposed solution involves a program operation that initializes memory cells to checkpoint states in the first pass, followed by programming to assigned data states in subsequent passes without verify tests, optimizing the number and configuration of checkpoint states to minimize read errors and maintain threshold voltage levels within an allowable range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If verify tests are performed in all programming passes, then programming accuracy is improved, but program time increases
Solution Approach 1:
The patent segments the programming process into multiple passes with different verify test strategies. First pass performs verify tests to establish checkpoint states, while second pass skips verify tests to reduce time. This segmentation allows the system to achieve both programming accuracy and reduced program time by applying appropriate verification only where necessary.
2Manufacturing precision
If multiple programming passes are used, then threshold voltage precision is improved, but program time increases
Solution Approach 1:
The first programming pass performs preliminary action by programming memory cells to checkpoint states with verify tests to establish accurate reference points. The second pass then builds upon this preliminary work by programming from checkpoint states to final data states without verify tests, leveraging the previously established accuracy to achieve final precision without the time cost of repeated verification.
3Loss of time
If verify tests are minimized in second pass, then program time is reduced, but programming accuracy may deteriorate
Solution Approach 1:
The first programming pass provides beforehand cushioning by establishing accurate checkpoint states through verify tests. These checkpoint states serve as a cushion or safety margin that ensures the second pass can proceed without verify tests while still maintaining programming accuracy. The preliminary verification creates a buffer that protects against potential accuracy deterioration in the optimized second pass.
Data Source
AI summary
Apparatuses and techniques are described for optimizing a program operation in a memory device in which groups of memory cells are programmed from checkpoint states to respective data states. In a first program pass, groups of memory cells are programmed to respective checkpoint states with verify tests. Each checkpoint state is associated with a set of data states. In a second program pass, the memory cells are programmed closer to their assigned data state with a specified number of program pulses. In a third program pass, the memory cells are programmed to their assigned data state by applying program pulses and performing verify tests. The number of checkpoint states and the number of data states associated with each checkpoint state can be optimized based on a spacing between the verify voltages of the data states.