Non-Volatile Memory Programming via Bit Line Precharging
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Solution Overview
Problem
Existing methods for programming non-volatile memory devices, such as NAND flash memory, face challenges in effectively inhibiting unselected memory cells from being programmed due to insufficient channel boosting, leading to program disturbance and reduced programming efficiency.
Innovation Solution
A method involving precharging bit lines connected to program-inhibited cells and applying specific voltage levels to word lines, including a program voltage and pass voltages, to achieve effective channel boosting and prevent unwanted programming of adjacent memory cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional programming voltage is applied to selected word line, then programming speed is improved, but program disturbance occurs in unselected memory cells
Solution Approach 1:
The patent applies preliminary anti-action by precharging bit lines connected to program-inhibited cells to a first pass voltage level before applying the programming voltage. This preliminary voltage application creates a protective potential barrier that prevents electrons from tunneling into the floating gates of unselected cells during the programming operation, thereby counteracting the harmful program disturbance effect before it can occur.
Solution Approach 2:
The patent implements local quality by applying different voltage levels to different bit lines based on their connection status. Bit lines connected to program-inhibited cells receive a first pass voltage (higher voltage level), while other bit lines receive a second pass voltage (lower voltage level). This localized differentiation ensures that only specific memory cells are protected from programming, allowing high-speed programming of selected cells while preventing disturbance in inhibited cells.
2Reliability
If bit lines are precharged to high voltage level, then program inhibition is improved, but voltage level control complexity increases
Solution Approach 1:
The patent applies preliminary action by precharging the bit lines to the first pass voltage level before the actual programming operation begins. This advance preparation ensures that when the programming voltage is applied to the selected word line, the inhibited cells are already protected by the elevated bit line voltage, eliminating the need for complex real-time voltage switching during programming.
Solution Approach 2:
The patent utilizes parameter changes by dynamically adjusting the voltage level on bit lines based on their connection status. The system changes the electrical parameter (voltage level) of bit lines from a default state to a protected state for inhibited cells, providing a simple and effective mechanism for program inhibition without requiring complex circuit modifications.
3Device complexity
If channel boosting is insufficient, then device complexity is reduced, but program disturbance increases
Solution Approach 1:
The patent introduces an intermediary mechanism by using the bit line voltage as a mediating factor between the programming voltage and the memory cells. The precharged bit line acts as an intermediary that transfers and modulates the electrical influence, ensuring that inhibited cells are protected from program disturbance through the voltage potential created on the bit line, rather than requiring direct channel boosting circuits.
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 ensures sufficient channel boosting, thereby preventing program disturbance and enhancing programming efficiency by maintaining the correct voltage levels across memory cells, ensuring effective program inhibition and improved programming speed.
Implementation Method 1
Programming is performed by injecting electrons of a channel area into a floating gate by Fowler-Nordheim (F-N) tunneling, which is generated due to a high voltage difference, between a channel area and a control gate of a selected memory cell
Data Source
AI summary
A method of programming a non-volatile memory device includes, a bit line, to which a program-inhibited cell is connected, being precharged. After precharging the bit line, a program voltage is applied to a first word line selected for program. When a memory cell connected to a second word line, which is adjacent to the first word line in a direction of a drain select line, is a cell to be programmed, a first pass voltage is applied to the second word line and a second pass voltage is applied to the remaining word lines other than the first and second word lines.