Non-volatile Memory Program Disturb Countermeasure
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Solution Overview
Problem
Program disturb occurs in semiconductor memory systems during programming processes, leading to unintended programming of memory locations and 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 pre-charging channels, applying voltage spikes, and delaying voltage ramp-downs to open and maintain communication between the source and drain sides of channels, thereby preventing electron acceleration and redirection, including the use of a control circuit to manage these processes for selected and unselected memory cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If boosting signals are applied to unselected control lines to prevent program disturb, then reliability is improved, but device complexity increases due to additional control circuit requirements
Solution Approach 1:
The patent applies boosting signals to unselected control lines before the programming operation begins. This preliminary action ensures that unselected memory cells are pre-charged and protected from program disturb before electrons can be accelerated during the programming process, thereby improving reliability without requiring complex real-time detection circuits
Solution Approach 2:
The patent segments the memory array into selected and unselected regions, applying different voltage signals to each. By dividing the control lines into selected control lines (receiving programming signals) and unselected control lines (receiving boosting signals), the system can independently manage programming and protection functions, reducing the need for complex unified control logic
2Reliability
If pre-charging operations are performed on unselected memory cells, then program disturb is prevented, but programming speed is reduced due to additional operation steps
Solution Approach 1:
The patent implements pre-charging operations periodically between programming pulses. By applying boosting signals at specific intervals during the programming sequence, the system maintains protection against program disturb while allowing programming to continue efficiently, balancing reliability and speed through rhythmic application of protective signals
Solution Approach 2:
The pre-charging operation is performed in advance before the main programming operation begins. By preparing unselected memory cells with boosting signals beforehand, the system eliminates the need for additional protection steps during programming, thus maintaining programming speed while ensuring data accuracy
3Reliability
If voltage spikes are applied during boosting to open channel communication, then program disturb countermeasure is enhanced, but energy consumption increases
Solution Approach 1:
The patent applies voltage spikes to unselected control lines to create a preliminary protective barrier before electron acceleration can occur. This anti-action counteracts the potential program disturb by opening channel communication in advance, preventing harmful electron migration while consuming energy only during the brief spike duration rather than continuously
Solution Approach 2:
Voltage spikes are applied periodically or selectively during specific phases of the programming operation rather than continuously. This periodic application provides necessary channel communication stability only when program disturb risk exists, significantly reducing overall energy consumption compared to continuous voltage application
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 electrical communication between channel sides, reducing data errors and maintaining accurate programming across memory locations.
Implementation Method 1
applying boosting signals to unselected control lines to boost channels of groups of connected non-volatile memory cells that include the second subset of memory cells
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.