Non-volatile Memory Programming Pulse Duration Control
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Solution Overview
Problem
Non-volatile semiconductor memory technologies face challenges in achieving higher programming voltages for multi-state memory cells due to limitations in pulse magnitude and cell coupling ratio, especially as technology scales to finer geometries, requiring larger voltages for effective programming while being constrained by practical design limitations.
Innovation Solution
An intelligent scheme for controlling the duration of program pulses in non-volatile storage elements, including applying pulses with increasing magnitudes and varying time durations between verification operations, allowing for effective programming even when maximum voltage is reached, using techniques such as wider pulses or multiple consecutive pulses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pulse magnitude is increased to program multi-state memory cells, then programming effectiveness is improved, but maximum voltage limit is reached which prevents further programming
Solution Approach 1:
The patent changes the pulse parameter from magnitude to duration. When the maximum voltage limit is reached, the system transitions from increasing pulse magnitude to increasing pulse duration (wider pulses or multiple consecutive pulses) to continue effective programming of memory cells without exceeding voltage constraints.
2Quantity of substance
If technology scales to finer geometries, then device density is improved, but larger voltages are required for programming which conflicts with design limitations
Solution Approach 1:
The patent addresses the voltage requirement issue by changing the temporal parameter of the programming pulse. Instead of relying on higher voltage magnitudes required by finer geometries, the system uses extended pulse duration to achieve the necessary programming effect, thereby maintaining compatibility with design voltage limitations while supporting scaled technologies.
3Duration of action of stationary object
If traditional pulse-based programming is used beyond maximum voltage, then programming continues, but programming rate decreases and effectiveness is reduced
Solution Approach 1:
The patent employs periodic action by applying multiple consecutive programming pulses between verification operations. This periodic application of pulses at maximum voltage with varying durations maintains the programming rate by systematically addressing memory cells that require additional programming, rather than allowing the process to stall or slow down significantly.
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 enables continued effective programming of memory cells beyond the maximum voltage limit, maintaining the programming rate and ensuring proper programming of memory cells by intelligently managing pulse duration and magnitude, thereby overcoming the limitations of traditional pulse-based programming methods.
Implementation Method 1
Electrons from the channel are injected into the floating gate. When electrons accumulate in the floating gate, the floating gate becomes negatively charged and the threshold voltage of the memory cell is raised
Implementation Method 2
When the threshold voltage is negative and a read is attempted by applying 0 volts to the control gate, the memory cell will turn on to indicate logic one is being stored. When the threshold voltage is positive and a read operation is attempted by applying 0 volts to the control gate, the memory cell will not turn on
Data Source
AI summary
To program a set of non-volatile storage elements, a set of programming pulses are applied to the control gates (or other terminals) of the non-volatile storage elements. The programming pulses have a constant pulse width and increasing magnitudes until a maximum voltage is reached. At that point, the magnitude of the programming pulses stops increasing and the programming pulses are applied in a manner to provide varying time duration of the programming signal between verification operations. In one embodiment, for example, after the pulses reach the maximum magnitude the pulse widths are increased. In another embodiment, after the pulses reach the maximum magnitude multiple program pulses are applied between verification operations.