Embedded Non-Volatile Memory: A Newsworthy Topic

The secure storage aspects of antifuse eNVM.


Hacking and security concerns for consumer electronics must be among the most newsworthy topics in the Top 10 tech stories these days. A hacking headline seems to regularly make it as the lead piece on every tech blog or news online.

No doubt, then, hacking is a Top 10 concern that consumers have when purchasing their electronics devices.

While no one would recommend using embedded non-volatile memory (eNVM) IP in business-to-consumer advertising, it is a differentiator and a way to keep hackers at bay. And relevant, too, because eNVM is a configurable block of embedded on-chip IP able to reduce costs, improve performance and, most important, enable secure storage without compromising reliability.

Operating systems have security holes and backdoors that can be exploited by hackers. Creating a secure, hack-proof device means calculating a wide range of possible vulnerabilities. Although there is no magic solution, eNVM is pretty close as secure storage for data protection.

ROM is the ideal eNVM solution for applications where the code is fixed, while flash-based technologies work well when code changes with thousands of cycles of program/erase endurance. Somewhere in the middle sits eNVM implemented in standard logic CMOS with no additional masks or processing steps. Polyfuse and floating gate are considered eNVM, as is antifuse one-time programmable (OTP), the most secure of this category. It also offers lower active and standby power.

Several factors make antifuse eNVM secure. Information programmed into an antifuse bitcell provides the physical security to make a system impenetrable. At the physical layer, considered a highly vulnerable spot, a protective layer is applied that it can’t be hacked via passive, semi-invasive or invasive methods. Because its bitcell does not store a charge, no physical evidence of the state of the non-volatile memory bitcell can be discovered. Instead, the bit determines an initial “0” or programmed “1” through the process of sensing current, not voltage.

Invasive tactics are thwarted by antifuse eNVM because information programmed into an antifuse bitcell provides physical security to make the system impenetrable. For example, the common backside attacks or SEM passive voltage contrasts are unsuccessful because it’s hard to isolate a bitcell connected in a cross point array. The passive approach using current profiles to determine word patterns fails as well. The bitcell current for “0” and “1” is smaller than the current needed for sensing or operating peripheral circuits to read the memory. Establishing programmed bits isn’t possible, either, because it is too difficult to locate the oxide breakdown using chemical etching or mechanical polishing or checking a cross-section or top view.

Security has become the most important design challenge in the consumer electronics market, but it’s quickly followed by cost as suppliers look for any opportunity to keep pricing low for volume growth. Set-top box, multimedia SoC, application processors, gaming and GPS system designs benefit from eNVM –– a secure, cost-effective, low-power and highly reliable on-chip memory.

Hackers may think they have the upper hand, but not with consumer electronics devices that have eNVM. That’s a newsworthy topic.