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Unity Semiconductor's RRAM patents

Recently it has been speculated that Hewlett-Packard may have prototypes of their memristor based RRAM as early as 2009 as a possible alternative to flash memory with nanoscale resolution storage densities. The use of resistance-based RAM actually has a fairly long history going back to reseach in the 1960's and 1970's by Stan Ovshinsky using chalcogenide glasses and Alan MacDiarmid using conductive polymers. HP's variation of RRAM is based on their nanoscale crossbar design which is distinguished from earlier designs in that it is a two-terminal resistance switch design formed for crossed nanowires sandwiching resistance switching molecular or thin film materials.

Another company involved in RRAM development is Unity Semiconductor. Unity Semiconductor was founded by Darrell Rinerson, a former head of Micron Technologies flash memory division, and has some fairly basic patents related to RRAM such as US Patent 6,870,755 in which claim 1 reads:

1. A 2-terminal re-writable memory cell, comprising:

a non-linear resistive memory element that can store non-volatile information; wherein

the resistance of the non-linear resistive memory element can be reversibly written to different values, whereby the resistance of the non-linear resistive memory is used to determine the stored information; and

the memory cell is accessed through exactly 2 terminals.

However, this and several other of Unity Semiconductor's patents have seemed to overlook prior art from HP such as US Patent 6,128,214 or earlier prior art such as US Patent 5,272,359 which clearly show non-linear resistance non-volatile memory formed with crossbar (i.e. 2-terminal) addressing which may cast considerable doubt on the validity of many of the more basic patents from Unity.

Full post as published by TinytechIP on July 20, 2008 (boomark / email).