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This paper demonstrates a cross point Cu based Resistive Random Access Memory (Cu-ReRAM) technology suitable for Storage Class Memory (SCM) applications. Two key technologies have been developed for large capacity of 100Gb-class SCM with 100 ns program speed and 10M cycles of program endurance. One is tight resistance distributions of Cu-ReRAM by inserting a barrier layer to prevent excess intermixing. The other is a novel Boron and Carbon (BC) based Ovonic Threshold Switch (OTS) selector which meets requirements for large cross point arrays with low leakage current, low threshold voltage variability, and high endurance.

An electron beam recorder (EBR) has been confirmed to have high-resolution performance and we think it is a promising recorder to produce a master stamper for the next-generation high-density optical disks. Because the high-density groove recording disk requires a narrower track pitch, the improvement of the recording resolution of the mastering recorder is necessary. However, owing to electron scattering, fabricating a groove structure was difficult even when we use a finely controlled conventional EB mastering process. A plasma etching process is an expected process as one of the solutions. Consequently, we adopted the plasma etching process for high-density groove disk mastering. A data bit length of 112 nm/bit was successfully recorded on the groove disk at a wavelength of 405 nm and an objective lens of 0.85 numerical aperture.

An inexpensive and practical mastering technology was developed using a blue-laser optical system with a wavelength λ of 405 nm and numerical aperture (NA) of 0.95 comprising an inorganic photoresist. The resist system showed a higher resolution for a successful 130 nm pit patterning than that obtained by an ordinary organic photoresist system. Based on this technology, a read only memory (ROM) disc with a recording capacity of 25.2 GB on a 120-mm-diameter surface was mastered at a high recording speed of 4.92 m/s. The disc showed a reasonable jitter value of 8.0% using a conventional equalizer, 4.6% using a limit equalizer and a push-pull signal using a conventional readout optical system of λ=405 nm and NA=0.85.

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 107 cycles 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.

We have fabricated a plasma-etched lens about three times larger than our previous design by using a novel selectivity control technique during transfer processes, and performed phase-change optical recording for the digital-video-recording (DVR)-blue format. We have fabricated an aspherical plasma etched lens using the selectivity control transfer technique.

A feasibility study of a magneto-optical(MO) disk for an NA 0.85 system is presented. The disk noise level in this system was relatively large compared to the conventional NA 0.55 system at the recording density corresponding to this spot size. Two methods were introduced for the improvement. One was the optimization of the groove structure, and the other was the reduction of the metal surface roughness. The former was found to be the typical noise source for optics for a narrower track pitch disk. A UV ashing apparatus was utilized for reduction of the noise. The latter noise source was characteristic for the surface MO recording, and the etching process was found effective for the improvement. By using both these methods, the noise level was drastically decreased, achieving high areal density of 7 Gb/inch2.

In order to investigate the vectorial magnetization process in magnetic recording media, a method of measuring the magnitude and the direction of remanent magnetization using a VSM is proposed. The magnitude and direction ψ of the remanent magnetization were measured as a function of the direction of applied field θ in Co-Cr thin-film media and a metal oblique-evaporated medium and metal particulate medium. The film thickness dependence of the relation between ψ and θ for Co-Cr sputtered film was measured and the thickness of the initial layer was estimated. The relation between ψ and θ was calculated by taking the distribution of the anisotropy fields and the easy axes into account. From the measurements and the calculations, it is shown that the relation between ψ and θ is strongly influenced by not only the saturation magnetization and the anisotropy field but also the distribution of the anisotropy fields and the easy axes.