Programmable ROM: Difference between revisions

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=== One time programmable memory ===

OTP (one time programmable) memory is a special type of [[non-volatile memory]] (NVM) that permits data to be written to memory only once. Once the memory has been programmed, it retains its value upon loss of power (i.e., is non-volatile). OTP memory is used in applications where reliable and repeatable reading of data is required. Examples include boot code, encryption keys and configuration parameters for analog, sensor or display circuitry. OTP NVM is characterized, over other types of NVM like [[eFuse]] or EEPROM, by offering a low power, small area footprint memory structure. As such, OTP memory finds application in products from microprocessors & display drivers to power management ICs (PMICs).

Commercially available semiconductor antifuse-based OTP memory arrays have been around at least since 1969, with initial antifuse bit cells dependent on blowing a capacitor between crossing conductive lines. [[Texas Instruments]] developed a MOS [[gate oxide]] breakdown antifuse in 1979.<ref>See [http://patimg2.uspto.gov/.piw?Docid=4184207&idkey=NONE US Patent 4184207] {{Webarchive|url=https://web.archive.org/web/20180427183945/http://patimg2.uspto.gov/.piw?Docid=4184207&idkey=NONE |date=2018-04-27 }} - High density floating gate electrically programmable ROM, and [http://patimg2.uspto.gov/.piw?Docid=4151021&idkey=NONE US Patent 4151021] {{webarchive|url=https://web.archive.org/web/20180427092847/http://patimg2.uspto.gov/.piw?Docid=4151021&idkey=NONE |date=2018-04-27 }} - Method of making a high density floating gate electrically programmable ROM</ref> A dual-gate-oxide two-transistor (2T) MOS antifuse was introduced in 1982.<ref>[http://www.chipestimate.com/techtalk/techtalk_071218.html Chip Planning Portal]. ChipEstimate.com. Retrieved on 2013-08-10.</ref> Early oxide breakdown technologies exhibited a variety of scaling, programming, size and manufacturing problems that prevented volume production of memory devices based on these technologies.