Keithley S530 FlashMemPulseAppNote free download

File name S530 FlashMemPulseAppNote.pdf

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