The Study Of Random Telegraph Signals In Flash Memory

Flash memory market has an explosive growth in the semiconductor memories' world. It is driven by the many types of electronic portable equipment. However, as devices'dimensions continue to shrink, random telegraph signals (RTS) will become a prominent issue in flash memory. The RTS limit the minimum signal level and lead challenges for device reliability. So this master thesis aims to find out the origin of RTS, quantify the value of RTS, get to know the characteristics of RTS and its tendency. In this master thesis, first we analyze the structure and working function of flash, and further to figure out the origin of RTS.And then we focus on two sides of random telegraph signals: one is the amplitude of random telegraph signals, and the other is the 1/f noise. The amplitude of random telegraph signals can be reflected by drain current fluctuation or gate voltage shift, and then further to be analyzed by the Fast Fourier Transformation to get the 1/f noise.We use LabVIEW software to program many VIs to control the front of semiconductor parameter analyzer (SPA). And then we use SPA to configure the drain source and gate of flash and further to measure the amplitude of RTS. And we got our satisfied results finally.This master thesis also discusses the impact on the random telegraph signals with different gate length and the impact on the random telegraph signals with the different numbers of program/erase cycles. Through the experimental results, we proved that RTS will be larger and larger as the flash dimension size is scaling down and RTS will increase over the number of program/erase cycles.