Non-Volatile Memory Programming Voltage Control
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Solution Overview
Problem
In non-volatile memory devices, unnecessary steps and overshooting occur due to the application of program and verify voltages to unselected word lines, leading to inefficiencies and potential errors in the programming process.
Innovation Solution
A programming method that applies a program voltage to a selected word line and a first pass voltage to unselected word lines, which then shifts to a second pass voltage of a lower level, while the verify operation uses a verify voltage with a level lower than the second pass voltage, eliminating the need for discharging the first pass voltage and preventing overshooting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a program voltage is applied to a selected word line and a pass voltage is applied to unselected word lines, then the programming operation can be performed, but unnecessary steps are performed and the process becomes complex
Solution Approach 1:
The patent extracts and eliminates the unnecessary step of applying a separate pass voltage to unselected word lines before the verify operation. By directly applying the verify voltage to the selected word line without the intermediate pass voltage step, the process is simplified while maintaining proper programming functionality.
Solution Approach 2:
The patent performs preliminary action by applying the pass voltage to unselected word lines during the program operation phase itself, rather than as a separate preliminary step before verify. This integrates the pass voltage application into the existing program operation sequence, eliminating redundant steps.
2Reliability
If a pass voltage is applied to unselected word lines before verify operation, then programming can be enabled, but overshooting occurs in the verify voltage due to influence from neighboring word lines
Solution Approach 1:
The patent removes the harmful factor by eliminating the pass voltage application step to unselected word lines that causes overshooting. The verify operation directly applies verify voltage without the preceding pass voltage that would cause capacitive coupling and overshooting effects.
Solution Approach 2:
The patent prevents overshooting by not applying the pass voltage to unselected word lines before verify operation. This preliminary anti-action avoids the capacitive coupling effect that would otherwise cause the verify voltage to overshoot due to influence from neighboring word lines.
3Productivity
If the first pass voltage is applied to unselected word lines, then the programming operation can proceed, but the time required for verify operation increases due to unnecessary steps
Solution Approach 1:
The patent extracts and removes the unnecessary time-consuming step of applying pass voltage to unselected word lines before verify operation. By directly transitioning from program voltage to verify voltage on the selected word line, the verify operation completes faster without the delay of the pass voltage step.
Solution Approach 2:
The patent performs preliminary action by applying pass voltage to unselected word lines during the program operation phase, so that when verify operation starts, the unselected word lines are already in the appropriate state, eliminating the need for a separate preliminary pass voltage step before verify.
Data Source
AI summary
In a programming method of a non-volatile memory device, a program operation is performed by applying a program voltage to a selected word line and a first pass voltage to unselected word lines. The first pass voltage shifts to a second pass voltage having a level lower than that of the first pass voltage. A verify operation is performed by applying a verify voltage to the selected word line. The verify voltage has a level lower than that of the second pass voltage.