Non-volatile Memory Program Disturb Countermeasure via Channel Purge
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Solution Overview
Problem
Program disturb in non-volatile memory systems causes unintended programming of memory locations during the programming process, leading to data errors due to electrons being accelerated and redirected across word lines, which existing technologies fail to adequately prevent.
Innovation Solution
Implementing countermeasures such as purging the already programmed side of the channel during pre-charge, applying a voltage spike to already programmed unselected word lines during boosting, and delaying the ramp-down of voltages on these lines after program verify to prevent electron acceleration and redirection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If electrons are accelerated across word lines during programming, then programming speed is improved, but program disturb occurs causing data errors
Solution Approach 1:
The channel is opened prior to the programming operation by applying a voltage to the unselected word line before electron acceleration occurs. This preliminary action prevents electrons from being redirected into the selected word line during programming, thereby eliminating program disturb while maintaining high programming speed.
Solution Approach 2:
A voltage signal is introduced as an intermediary mechanism to control the channel state. By applying this voltage to the unselected word line during the programming operation, the channel is kept open to prevent electron redirection, thus protecting data integrity without sacrificing programming performance.
2Reliability
If channel is kept closed during programming, then program disturb is prevented, but programming process becomes slower
Solution Approach 1:
The channel state is dynamically adjusted during the programming operation. The channel is opened during the critical programming phase when electron acceleration occurs, then closed afterward. This dynamic control allows the system to maintain both high programming efficiency and data integrity by having the channel open only when needed to prevent program disturb.
Solution Approach 2:
The channel opening and closing is performed as a periodic action synchronized with the programming pulses. The channel is opened during each programming pulse to prevent electron redirection, then closed between pulses. This periodic control ensures data integrity while allowing continuous high-speed programming operations.
3Reliability
If voltage is applied to unselected word lines during programming, then program disturb is prevented, but power consumption increases
Solution Approach 1:
Voltage is applied selectively only to the unselected word lines that are adjacent to the selected word line, rather than to all word lines in the memory array. This localized approach prevents program disturb in the critical region while minimizing overall power consumption by avoiding unnecessary voltage application to distant word lines.
Solution Approach 2:
The voltage level applied to unselected word lines is optimized to the minimum necessary level to keep the channel open and prevent electron redirection. By carefully controlling the voltage parameter, the system achieves effective program disturb prevention while minimizing the energy required to maintain this protective state.
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
Effectively prevents program disturb by ensuring that electrons are not inadvertently programmed into untargeted memory cells, thereby maintaining data accuracy and integrity during memory operations.
Implementation Method 1
Program disturb is a condition that includes the unintended programming of one or more locations in a memory while performing a programming process for other locations in the memory. Such unintended programming can cause an error in the data being stored. In some cases, program disturb can result from electrons trapped in the channel being accelerated from one side of a selected word line to another side of the selected word line and redirected into the selected word line.
Implementation Method 2
The control circuit is configured to pre-charge channels of unselected groups prior to the applying boosting signals and apply a bypass voltage to one or more already programmed unselected control lines adjacent to the selected control line while pre-charging channels of unselected groups.
Data Source
AI summary
Program disturb is a condition that includes the unintended programming of a memory cell while performing a programming process for other memory cells. Such unintended programming can cause an error in the data being stored. In some cases, program disturb can result from electrons trapped in the channel being accelerated from one side of a selected word line to another side of the selected word line and redirected into the selected word line. To prevent such program disturb, it is proposed to open the channel from one side of a selected word line to the other side of the selected word line after a sensing operation for program verify and prior to a subsequent programming voltage being applied.