01-12-2012, 04:45 PM
Flash Memory
[attachment=42124]
What is Flash Memory?
A type of Non-Volatile memory
A specific type of EEPROM (Electrically Erasable Read Only Programmable Memory)
Solid-State Memory
Device Structure
Similar to MOSFET Structure
Added Floating Gate (FG) between Control Gate (CG) and inversion layer
FG surrounded by insulators
FG traps electrons (~50 years)
CG is same as MOSFET gate
Charged FG disrupts / affects inversion layer
Current flows from the drain to source via inversion layer
Read Function
Flash Memory senses the amount of current flowing through its inversion layer as a means of logic state determination.
Write Function
Electrons are injected into the FG via hot-electron injection
Charged FG partially cancels the CG’s E-field
Vt is modified, changing current flow (less)
Reduced current flow in inversion layer - logic 0
Lifespan
Hot electron injection or tunneling results in device deterioration
Electrons have a probability of becoming trapped in oxide layer, electron traps
Trapped electrons in oxide disrupt Vt
Flash Memory can “wear out”
Between 1,000 10,000 and up to 100,000 write cycles
[attachment=42124]
What is Flash Memory?
A type of Non-Volatile memory
A specific type of EEPROM (Electrically Erasable Read Only Programmable Memory)
Solid-State Memory
Device Structure
Similar to MOSFET Structure
Added Floating Gate (FG) between Control Gate (CG) and inversion layer
FG surrounded by insulators
FG traps electrons (~50 years)
CG is same as MOSFET gate
Charged FG disrupts / affects inversion layer
Current flows from the drain to source via inversion layer
Read Function
Flash Memory senses the amount of current flowing through its inversion layer as a means of logic state determination.
Write Function
Electrons are injected into the FG via hot-electron injection
Charged FG partially cancels the CG’s E-field
Vt is modified, changing current flow (less)
Reduced current flow in inversion layer - logic 0
Lifespan
Hot electron injection or tunneling results in device deterioration
Electrons have a probability of becoming trapped in oxide layer, electron traps
Trapped electrons in oxide disrupt Vt
Flash Memory can “wear out”
Between 1,000 10,000 and up to 100,000 write cycles