Using Hot Carrier Injection for Embedded Non-volatile Memory

Since the invention of NAND Flash memory in the 1980’s, non-volatile memory (NVM) has touched all aspects of our daily life. Applications for NVM is growing everyday from handy data storage devices like a USB Flash Drive to High Definition Multimedia Interface (HDMI) and its high-bandwidth digital content protection (HDCP) encryption algorithms to firmware storage in a variety of digital devices like digital cameras and mobile phones. Some CPU and ASIC designs still use legacy non-volatile memory technology such as fuse or electric fuse (efuse), but the bit cell is larger than newer technologies so it is not so attractive for higher bit count memory arrays and it is typically not field programmable. Other designs use embedded Flash, but current Flash memory technology requires a special fabrication process if it is embedded in existing CMOS logic; this significantly increases the chip cost. Finally, in the last few years, newer NVM technologies such as oxide-rupture and floating gate have entered the market and have been incorporated into more and more designs. These technologies do not have the area penalty of fuse/e-fuse and do not have the additional processing costs of embedded Flash, but have their own unique disadvantages in terms of process scaling, testability, and security. A new technology that uses hot carrier injection for non-volatile data storage is now available as an embedded non-volatile memory solution. Similar to floating gate and oxide-rupture, this technology does not have the limitations of fuse/e-fuse and Flash, but unlike those technologies, it also performs well in terms of process scaling, testability, and security.