Dummy Memory Cell Voltage Control for Program Disturbance
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Solution Overview
Problem
In highly integrated nonvolatile memory devices, a disturbance phenomenon occurs where unselected memory cells adjacent to the selected memory cell can be programmed during a programming operation, necessitating a technology to prevent this disturbance.
Innovation Solution
A nonvolatile memory device with a string structure that includes a dummy memory cell and a voltage generator to apply a disturbance prevention voltage to the dummy memory cell based on its distance from the selected memory cell, preventing unselected memory cells from being programmed by adjusting the voltage levels on the dummy word line relative to the selected word line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a programming operation is performed on a selected memory cell in a highly integrated nonvolatile memory device, then the storage capacity can be increased, but unselected memory cells adjacent to the selected memory cell may be programmed due to disturbance
Solution Approach 1:
A dummy memory cell is introduced as an intermediary element between the ground select transistor and the actual memory cells. This dummy cell serves as a mediator that absorbs excess hot carriers generated during programming operations, preventing them from disturbing adjacent unselected memory cells. The dummy cell is configured with specific voltage characteristics that allow it to intercept and dissipate harmful carriers while maintaining normal operation of the actual memory array.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the voltage levels applied to the dummy memory cell based on the distance between the dummy cell and the selected memory cell. The voltage generator modifies the disturbance prevention voltage in real-time according to the specific programming location, optimizing the protective effect while minimizing impact on adjacent cells. This dynamic parameter adjustment allows the system to maintain high integration density while preventing program disturbances.
2Reliability
If a dummy memory cell is added to prevent disturbance, then program disturbance is prevented, but device complexity increases
Solution Approach 1:
The dummy memory cell is designed to serve multiple functions simultaneously: it acts as a protective element against hot carrier disturbances, serves as a voltage reference for adjacent cells, and maintains the electrical continuity of the string structure. By making the dummy cell multi-functional, the patent reduces the need for separate protective circuits, thereby limiting the increase in device complexity while achieving reliable disturbance prevention.
3Reliability
If disturbance prevention voltage is applied to the dummy memory cell, then unselected memory cells are protected from programming, but voltage control complexity increases
Solution Approach 1:
The voltage generator is designed to automatically adjust the disturbance prevention voltage based on the distance between the dummy memory cell and the selected memory cell without requiring external intervention. The system self-regulates by detecting the programming location and autonomously selecting appropriate voltage levels, thereby protecting unselected cells while avoiding the need for complex external voltage 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
The solution effectively prevents program disturbances due to hot carriers by controlling the voltage levels on the dummy word line, enhancing the reliability of nonvolatile memory devices by ensuring that only the intended memory cell is programmed.
Implementation Method 1
a disturbance phenomenon may occur whereby an unselected memory cell adjacent to the selected memory cell may be programmed when a program operation is performed
Data Source
AI summary
A nonvolatile memory device including a dummy memory cell and a method of programming the same, wherein the nonvolatile memory device includes a dummy memory cell, and a plurality of memory cells serially connected to the dummy memory cell. The nonvolatile memory device sets a voltage provided to the dummy memory cell according to a distance between a selected memory cell among the plurality of memory cells and the dummy memory cell when a program operation is performed.