K. Aratani

We report a novel nonvolatile dual-layered electrolytic resistance memory composed of a conductive Cu ion activated layer and a thin insulator for the first time. An ON/OFF mechanism of this new type memory is postulated as follows: Cu ions pierce through the insulator layer by applied electric field, the ions form a Cu conductive bridge in the insulator layer, and this bridge dissolves back to the ion activated layer when the field is reversed. The 4 kbit memory array with 1T-1R cell structure was fabricated based on 180 nm CMOS process. Set/reset pulses were 5 ns, 110 muA and 1 ns, 125 muA, respectively. Those conditions provide large set/reset resistance ratio of over 2 orders of magnitude and satisfactory retention. Essential characteristics for high capacity memories including superb scalability down to 20 nmphi, sufficient endurance up to 10⁷cycles and preliminary data for 4-level memory are also presented. These characteristics promise the memory being the next generation high capacity nonvolatile memory even before the scaling limitation of flash memories is encountered.

An inexpensive and practical mastering technology was developed by using blue laser optics of 405 nm in wavelength /spl lambda/ and NA=0.95 with an inorganic photoresist. The resist system showed a higher resolution for successful 130 nm pit patterning than that of ordinary organic photoresist systems. Based on this technology, a ROM disc with a recording capacity of 25 GB on a 120 mm diameter surface was mastered at a fast recording speed of 4.92 m/s. The disc showed a reasonable jitter value of 9.3% and a push-pull signal by using conventional readout optics of /spl lambda/=405 nm and NA=0.85.