Volatile Selector Relaxation Time Reduction via Opposite Polarity Pulse
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Solution Overview
Problem
The relaxation time of volatile selectors in cross-bar arrays, which can take up to milliseconds to transition from a high conductive state to a low conductive state, significantly slows down the operation of nanoscale memory devices, allowing sneak currents and preventing efficient reading or programming of non-volatile storage devices.
Innovation Solution
An electrical operation protocol involving a short voltage pulse of opposite polarity and duration is applied after programming or read pulses to reduce the relaxation time of volatile selectors from microseconds to tens of nanoseconds, ensuring the selector returns to its low conduction state quickly and preventing leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a voltage pulse is applied to switch the volatile selector to high conductive state for reading or programming, then the selector enables current flow through the non-volatile storage device, but the selector remains in high conductive state for an extended relaxation time (microseconds to milliseconds) after the pulse is removed
Solution Approach 1:
A relaxation reduction pulse is applied immediately after the programming or read pulse to proactively reduce the relaxation time before sneak currents can become problematic. This preliminary action prevents the harmful effect from developing by quickly returning the volatile selector to its low conductive state.
Solution Approach 2:
The relaxation reduction pulse applies an opposite polarity voltage to counteract the remaining high conductive state of the volatile selector. This anti-action directly opposes the unwanted relaxation effect and forces the selector to return to its low conductive state, preventing sneak currents from affecting subsequent operations.
2Object-generated harmful factors
If the volatile selector remains in high conductive state during relaxation time, then sneak currents can flow through other memory cells in the cross-bar array, but applying a relaxation reduction pulse requires additional voltage pulses and control complexity
Solution Approach 1:
The same voltage pulse generation circuitry used for programming and reading operations is also used to generate the relaxation reduction pulse. By making the control circuit multi-functional, the patent eliminates the need for separate dedicated relaxation reduction circuitry, thereby reducing overall device complexity while still effectively preventing sneak currents.
3Speed
If the relaxation time is reduced using a relaxation reduction pulse, then the cross-bar array's random-access time is significantly reduced and operation speed is improved, but the volatile selector requires additional voltage pulses to maintain proper state transitions
Solution Approach 1:
The relaxation reduction pulse is merged with the existing programming and read pulse sequences in the control logic. By combining multiple functions (programming, reading, and relaxation reduction) into a unified pulse generation scheme, the patent reduces the overall complexity of the control system while achieving fast operation speeds.
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 protocol significantly reduces the cross-bar array's random-access time, enabling faster operation and preventing sneak currents, thus making nanoscale memory devices more suitable for high-speed applications by ensuring efficient data access and storage.
Implementation Method 1
The volatile selector is characterized as having a relaxation time when transitioning from its high conductive state to its low conductive state
Implementation Method 2
The nanoscale electronic devices are configured with fast drift ionic species
Data Source
AI summary
In one example, a volatile selector is switched from a low conduction state to a first high conduction state with a first voltage level and then the first voltage level is removed to activate a relaxation time for the volatile selector. The relaxation time is defined as the time the first volatile selector transitions from the high conduction state back to the low conduction state. The volatile selector is switched with a second voltage level of opposite polarity to the first voltage level to significantly reduce the relaxation time of the volatile selector.