Read Back of Stored Data in Non Volatile Memory Devices by Scanning Capacitance Microscopy

Abstract

ABSTRACTThis report outlines a methodology for reading back different electrical charges, from Non Volatile Memory (NVM) based Flash devices. The charge is stored in the floating gates (FGs) of the transistors. Reading back these charges in the form of logic levels of “1 bit (1b)” and “0 bit (0b)” without deleting the information from the device was the goal. Scanning Capacitance Microscopy (SCM) with ∼50-100 nm spatial resolution was used, to directly probe the charge on Floating Gate Transistor (FGT) channels. Transistor charge values (ON/OFF or “1b/0b”) are measured. Both the sample preparation and SCM probing methods are discussed. The application has been demonstrated with SanDisk based 64 MB NAND Flash memory device.