Agilent Technologies B1500A Training Manual page 108

Flash Memory – Endurance Test
1 million Write/Erase cycle test
Start
Initial Write/Erase Test
Next burst test
i <= 10^6
F
Burst Write/Erase Test
Write
Measure Vth (*1)
Erase
Measure Vth (*2)
Endurance test is a kind of reliability tests. Repetitive write (program) and erase pulses are applied
to the cell and the Vth of the cell is monitored after certain number of pulses are applied. This test
is important because the flash memory is used for the data and file storage application. Then the
failure rate must be less than one percent for one million write/erase cycles. Therefore, for device
development, the endurance test is the critical test to make sure that the durability of the cell can
meet the target.
When measuring characteristics after certain number of write-erase cycling, Id(on) and Id(off) are
measured besides Vth depending on the cell type. In case of the cell types which use the F-N
tunneling between substrate and floating gate, sub-threshold swing is also measured after erasing
the cell.
T
End
(*1) Id(on) and Id(off)
are measured as well.
(*2) Id(on), Id(off) and
sub-threshold swing (S-
factor) are measured as
well.
13-24
SPGU Control and Applications
Write/
Program
Erase
1
0 2 3 4
10 10 10 10 10 10
Cycles
Module 13
5 6
10