Text preview for : S530 FlashMemPulseAppNote.pdf part of Keithley S530 FlashMemPulseAppNote Keithley SCS S530 S530 FlashMemPulseAppNote.pdf
Back to : S530 FlashMemPulseAppNote | Home
Number 3177
Application Note Programming and Erasing Flash Memory
Series Devices Using the Keithley S530 Pulse
Generator Option
Introduction and Background storage density and is by far the most dominant of the two types,
so this note will focus on NAND flash memory.
Normally, in parametric test, the instrument used most is the
Source Measurement Unit (SMU). The SMU allows supplying In addition to the floating gate, NAND flash memory cells
a DC voltage or current to the device under test (DUT) and (Figure 1) usually have a control gate, drain, source, and bulk.
simultaneously measuring the resultant voltage or current. The memory cell is set (programmed) and reset (erased) by
However, there are some cases where it's necessary to apply a applying or removing charge from the floating gate. Charge can
voltage to the device in a time-controlled manner. Often, the be applied or removed from the floating gate of any type of flash
duration of these applied voltages must be on the order of a few memory cell via Fowler-Nordheim (FN) current tunneling or via
microseconds in order to prevent the DUT from over-heating or Hot Carrier Injection (HCI). In a normal CMOS transistor, both
being over-stressed. SMUs are not designed to output voltages of these mechanisms cause device degradation and are usually to
this quickly. Therefore, a different instrument is required: a be avoided, but they are beneficial for flash memory. Moreover,
pulse generator. although FN tunneling and HCI are useful for programming and
erasing flash memory, they are also why flash memory cells have
A pulse generator allows outputting a voltage in a time-
a limited lifetime.
controlled, time-accurate manner, including control over the
amount of voltage (pulse height), the duration of the pulse
(pulse width), as well as the voltage ramp rate (rise and fall
time). This type of instrument also provides the ability to control
the number of pulses that are output and even to synchronize Polysilicon control gate
Sidewall Sidewall
multiple pulses. ONO Dielectric
Polysilicon floating gate
The Keithley S530 Parametric Test System offers a pulse Tunnel oxide
generator option that offers two to six channels of pulse outputs, N+ Source N+ Drain
each of which is capable of outputting a maximum of