The flash memory was conceived as a functional improvement of the erasable programmable read only memory (EPROM), which was invented in the 1980s from the initial idea of Frohman-Bentchkowsky [1]. The EPROM memory electrically programmed and erased by ultraviolet (UV) irradiation became the most important nonvolatile memory (NVM) application in the 1980s. The flash memory, called flash because the whole memory array is erased at the same