Predictive Programming for Non-Volatile Memory Cells
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Solution Overview
Problem
Conventional non-volatile memory programming techniques require numerous verify operations, especially for multi-level memory cells, leading to time-consuming programming processes and reduced performance.
Innovation Solution
A predictive programming method that uses a predetermined linear function to estimate the programming voltage needed for a given memory cell to reach a target threshold voltage level, eliminating the need for verify operations and improving programming efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional programming techniques with multiple verify operations are used, then programming accuracy is improved, but programming time increases significantly
Solution Approach 1:
The patent applies preliminary action by performing a single verify operation at a predetermined checkpoint during programming, then using this result to predict and determine the final programming voltage without requiring additional verify operations. This preliminary verification enables the system to advance confidently to the final programming state, eliminating the time-consuming iterative verify cycles of conventional techniques while maintaining accuracy through the predictive model.
Solution Approach 2:
The patent implements feedback by using the result of the single verify operation at the checkpoint to feed back into the programming voltage prediction. The verified threshold voltage at the checkpoint is used to calculate the final programming voltage through a predetermined function, creating a feedback loop that ensures accuracy while avoiding repeated verification cycles.
2Quantity of substance
If multi-level memory cells are programmed with conventional techniques, then storage capacity is improved, but the number of verify operations increases
Solution Approach 1:
For multi-level memory cells, the patent performs a single verify operation at a predetermined checkpoint to determine a checkpoint threshold voltage. This preliminary action enables the system to use a predetermined function to calculate the final programming voltage for any target state, eliminating the need for multiple verify operations that would traditionally be required to program each possible state, thus reducing device complexity while maintaining high storage capacity.
3Productivity
If the number of verify operations is reduced, then programming speed is improved, but programming reliability may deteriorate
Solution Approach 1:
The patent maintains programming reliability by implementing a feedback mechanism where a single verify operation at a checkpoint provides feedback to determine the final programming voltage through a predetermined function. This feedback approach ensures that the programming process is grounded in actual measured data while avoiding the redundancy of multiple verify operations, thus maintaining reliability without sacrificing speed.
Solution Approach 2:
The patent replaces the mechanical iterative verify-check-program cycle with a predictive model based on a predetermined function. Instead of mechanically repeating verify operations to ensure reliability, the system uses a mathematical model derived from the single verify operation to predict the final programming voltage, substituting mechanical verification with predictive calculation while maintaining reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces the time required for programming by minimizing the number of verify operations, while statistically predictable errors can be handled through error correction codes, enhancing overall performance and capacity of non-volatile memory.
Implementation Method 1
The threshold voltage characteristic of the transistor is controlled by the amount of charge that is retained on the floating gate
Implementation Method 2
A control gate is then provided over the floating gate. The threshold voltage characteristic of the transistor is controlled by the amount of charge that is retained on the floating gate
Data Source
AI summary
In a nonvolatile memory having an array of memory cells, wherein the memory cells are individually programmable to one of a range of threshold voltage levels, there is provided a predictive programming mode in which a predetermined function predicts what programming voltage level needs to be applied in order to program a given memory cell to a given target threshold voltage level. In this way, no verify operation needs to be performed, thereby greatly improving the performance of the programming operation. In a preferred embodiment, the predetermined function is linear and is calibrated for each memory cell under programming by one or more checkpoints. The checkpoint is an actual programming voltage that programs the memory cell in question to a verified designated threshold voltage level.