Memory (Contd..) Memory Timing: Definitions ETEG 431 SG

Memory Semiconductor Memory Classification ETEG 431 SG Read-Write Memory Non-Volatile Read-Write Memory Read-Only Memory EPROM E 2 PROM FLASH Random Access Non-Random Access SRAM DRAM Mask-Programmed Programmable (PROM) FIFO Shift Register CAM LIFO

Memory Read-Only Memory Cells ETEG 431 SG WL BL WL BL 1 WL BL WL BL WL BL 0 V DD WL BL GND Diode ROMMOS ROM 1MOS ROM 2

Memory MOS OR ROM ETEG 431 SG

Memory EPROM: Floating-Gate Transistor Programming ETEG 431 SG 0 V DS Removing programming voltage leaves charge trapped 5 V DS Programming results in higherV T. 20 V DS Avalanche injection

Memory EEPROM ETEG 431 SG Floating gate Source Substrate p Gate Drain n 1 n 1 20–30 nm 10 nm WL V DD

Memory Flash EEPROM ETEG 431 SG Control gate erasure p-substrate Floating gate Thin tunneling oxide n 1 source n 1 drain programming