Memory Cell Overwrite Mode via Threshold Voltage Progression
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Solution Overview
Problem
Conventional memory programming operations require intervening erase operations, which increase latency and reduce efficiency, as they need to reset threshold voltage levels before new data can be stored in memory cells.
Innovation Solution
Implementing direct overwrite mode by sequentially charging memory cells to higher threshold voltage levels without intervening erase operations, allowing multiple programming operations to be performed before a full erase is necessary, thus eliminating the need for intermediate erase steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional memory programming operations are used with intervening erase operations, then memory cells can be reset to initial state, but programming latency increases and efficiency decreases
Solution Approach 1:
The patent applies preliminary action by pre-charging memory cells to higher threshold voltage levels during programming operations, so that when data needs to be overwritten, the cells are already in a state that allows direct writing without requiring a full erase cycle. This prepares the memory cells in advance to accept new data directly at elevated voltage levels, eliminating the need for intermediate erase operations and reducing programming latency.
2Ease of operation
If intervening erase operations are performed before programming, then memory cells are prepared for new data, but media management frequency increases
Solution Approach 1:
The patent applies parameter changes by modifying the threshold voltage levels of memory cells during programming operations. Instead of erasing cells to a fixed initial state, the system programs cells to progressively higher threshold voltage levels. This changes the operational parameter from binary erase/write cycles to multi-level voltage programming, allowing multiple data writes without erasing previously stored data, thereby reducing media management frequency and improving productivity.
3Productivity
If multiple programming operations are performed without erase, then write efficiency improves, but threshold voltage levels must be sequentially increased
Solution Approach 1:
The patent applies dynamics by making the threshold voltage levels dynamic rather than static. Instead of using a fixed initial state for memory cells, the system dynamically adjusts and increases threshold voltage levels with each programming operation. This dynamic approach allows the same memory cell to be programmed multiple times at progressively higher voltage levels, improving write efficiency while managing the increased complexity through controlled voltage progression.
Data Source
AI summary
Described are systems and methods for performing memory programming operations in the overwrite mode. An example memory device includes: a memory array comprising a plurality of memory cells electrically coupled to a plurality of wordlines and a plurality of bitlines; and a controller coupled to the memory array, the controller to perform operations comprising: responsive to identifying a first data item to be stored by a portion of the memory array, causing a first memory programming operation to be performed to program, to a first target threshold voltage, a set of memory cells included by the portion of the memory array; and responsive to identifying a second data item to be stored by the portion of the memory array, causing a second memory programming operation to be performed to program the set of memory cells to a second target threshold voltage exceeding the first target threshold voltage.