Retention (NVRAM)

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Retention is a term from microelectronics , especially the technology of NVRAMs , i.e. non-volatile memory. This is a minimum time specified by the manufacturer of the memory in which information that has been stored remains error-free, i.e. no data loss occurs. That never means a guarantee against data loss. Typical values ​​range up to 20 years, although additional conditions (time of the module under operating conditions, temperature profiles during operation and storage) can be named. In some cases, error correction methods are used to achieve such retention values .

The technical reason for the restriction of the retention of an NVRAM with the flash memories commonly used today is the spontaneous (i.e. at most statistically detectable) migration of electrons from the central storage functional part of the memory cell, the floating gate . In order to improve the behavior, as a rule - apart from optimizing the manufacturing process (see semiconductor technology ) - only a certain insulation layer in the memory cell structure can be made thicker, which can lead to limitations in a second parameter of an NVRAM, the endurance .