Manufacturing Effects on Data Retention of Nonvolatile Memory Devices

摘要

Charge is stored on floating gates, and heat coupled with a loss of charge can cause a "bit-flip." Is this a significant problem? Many automotive electronics have flash-based microcontrollers in mission critical applications. The last thing an automotive company or EMS vendor wants is a recall due to problems with data retention in one of the control modules. As such, some engineers are reluctant to upgrade from slow (and costly) boundary scan or other in-sys-tem programming methods because they permit post-soldering programming. Our position: it's not a problem. Let's review why. Every semiconductor manufacturer that produces non-volatile memory (NVM) has to verify that data retention for a new design is sufficient and establish a quality procedure for monitoring data retention in production. Typically they will test for loss of data at elevated temperatures; then, using a relationship called the T-Model, calculate the equivalent lifetime for normal temperature ranges.