Flash Memory Floating Gate Electron Injection Method
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Defects in the manufacturing process of flash memory devices can lead to electron accumulation in the tunnel oxide layer, causing incorrect read states and resulting in data loss and read errors due to electrons stuck between the floating gate and the control gate.
Innovation Solution
A method involving the steps of erasing the floating gate, using a weak electric field to inject a small amount of electrons into the floating gate, and employing an electric field of a normal write to prevent channel conduction, thereby avoiding electron accumulation in the tunnel oxides and ensuring accurate data access and writing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If electrons are injected into the floating gate using normal write operation, then data can be written into the memory cell, but electron accumulation occurs in the tunnel oxide layer causing read errors and data loss
Solution Approach 1:
The patent applies preliminary action by performing an erase operation followed by a preliminary weak electron injection before the normal write operation. This preliminary action clears any accumulated electrons from the tunnel oxide layer and sets the floating gate to a known initial state, preventing subsequent read errors caused by electron accumulation during the write process
Solution Approach 2:
The patent changes the electrical parameters by using a weak electric field for preliminary electron injection compared to the strong electric field used in normal write operations. This parameter change allows controlled electron injection that prevents tunnel oxide accumulation while still preparing the floating gate for subsequent data writing, thereby maintaining read reliability
2Reliability
If electrons accumulate in the tunnel oxide layer, then the D-S channel formation is blocked, but incorrect read states are produced and data integrity is compromised
Solution Approach 1:
The patent converts the harmful effect of electron accumulation in the tunnel oxide layer into a beneficial process by using controlled weak electron injection. This deliberate injection creates a known initial electron distribution that prevents uncontrolled accumulation during write operations, transforming a potential reliability issue into a controlled preparation step that ensures data integrity
3Reliability
If a weak electric field is used to inject electrons, then electron accumulation in tunnel oxide is avoided, but insufficient electrons are injected for complete data writing
Solution Approach 1:
The weak electric field electron injection serves as a preliminary action that prepares the floating gate by establishing a controlled baseline electron distribution. This preliminary step does not complete the full data writing but creates optimal conditions for the subsequent normal write operation, ensuring both reliability and productivity
4Productivity
If normal write operation is performed without prior erasure, then writing speed is maintained, but electron overlap with existing information causes data loss
Solution Approach 1:
The patent applies preliminary erasure and weak electron injection actions before the normal write operation. This preliminary preparation removes existing electron distributions and accumulated electrons from the tunnel oxide, ensuring that the subsequent fast write operation does not cause electron overlap and data loss, thereby maintaining both speed and data integrity
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 method effectively prevents data loss and reduces the possibility of read errors by maintaining the integrity of the floating gate's electron state, ensuring correct data representation and preventing overlap of new data with existing information.
Implementation Method 1
When the floating gate (FG) has sufficient electrons, an electric field effect is created in the floating gate (FG) to prevent the formation of the D-S channel between the source (S) and the drain (D)
Implementation Method 2
hot electrons may get stuck in the tunnel oxide (TO) between the floating gate (FG) and the control gate (CG) over time, and the electrons will continue to accumulate in the tunnel oxide (TO)
Implementation Method 3
using an electric field of a normal write to inject electrons in the floating gate (FG) to prevent channel conduction between the source (S) and drain (D)
Data Source
AI summary
A method to prevent loss of data of transistor-based memory unit including bulk, source and drain formed on bulk and first tunnel oxide, floating gate, second tunnel oxide and control gate stacked up on channel between source and drain is disclosed to include steps of: erasing the floating gate, using weak electric field inject small amount of electrons into floating gate, enabling small amount of electrons to remain in floating gate to keep channel between source and drain electrically conducted, enabling small amount of electrons in floating gate to repel against electrons in first tunnel oxide and second tunnel oxide so as avoid electron accumulation in first tunnel oxide and second tunnel oxide and allow normal data access floating gate, and using electric field of normal write to inject electrons in floating gate so as to prevent channel conduction between source and drain and allow writing data into floating gate.