Semiconductor Device Floating Unselected Word Lines
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Solution Overview
Problem
Semiconductor devices face challenges in maintaining channel boosting of unselected cell strings during program operations, leading to unintentional programming of unselected memory cells due to reduced channel voltage.
Innovation Solution
A semiconductor device and operating method that temporarily float unselected word lines while applying program and pass voltages to selected word lines, using a control circuit to manage voltages and prevent channel voltage reduction in unselected cell strings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If channel boosting is performed by applying pass voltage to unselected word lines, then channel voltage of unselected cell strings is increased to prevent unintentional programming, but channel boosting may be reduced during program operation causing channel voltage to decrease
Solution Approach 1:
The control circuit applies pass voltage to unselected word lines before the program operation starts, establishing channel boosting in advance. This preliminary action ensures that when the program voltage is applied to selected word lines, the unselected cell strings already have elevated channel voltage to prevent unintentional programming.
Solution Approach 2:
The control circuit maintains pass voltage application to unselected word lines continuously throughout the program operation, ensuring channel boosting persists without interruption. This continuous action prevents channel voltage from decreasing and maintains protection against unintentional programming during the entire programming process.
2Reliability
If pass voltage is applied to unselected word lines to maintain channel boosting, then unselected memory cells are protected from programming, but device complexity increases due to additional control requirements
Solution Approach 1:
The control circuit performs multiple functions using the same pass voltage application mechanism: it maintains channel boosting for unselected cell strings, prevents unintentional programming, and manages voltage distribution throughout the memory array. This multi-functionality reduces the need for separate dedicated circuits for each function.
Solution Approach 2:
The control circuit automatically manages pass voltage application to unselected word lines based on the program operation state, eliminating the need for external manual control. The system self-regulates voltage distribution to maintain channel boosting and prevent unintentional programming without additional complex control mechanisms.
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
Prevents unintentional programming of unselected memory cells by maintaining channel voltage in unselected cell strings, enhancing the reliability of semiconductor devices during program operations.
Implementation Method 1
Channel boosting is an increase in the channel voltage due to coupling between a pass voltage applied to unselected word lines and the program inhibition voltage applied to the channel
Data Source
AI summary
A semiconductor device according to an embodiment may include cell strings including a plurality of memory cells coupled between bit lines and a source line and coupled to word lines, a peripheral circuit suitable for programming selected memory cells coupled to a selected word line among the word lines by applying a program voltage to the selected word line, and applying one or more pass voltages to unselected word lines, and a control circuit suitable for controlling the peripheral circuit to temporarily float the unselected word lines while the selected memory cells are programmed.