We have fabricated a thin head composed of a double layer magnetoresistive (MR) reproducing element and an inductive recording element for high density rigid disk drives. We have also developed a low noise reproducing amplifier IC whose input noise level is 0.3nV/Hz. Our experimental results indicate that equal electrical potential between the exposed area of the MR element and the medium's surface improves the durability of our MR head.

An electron beam cell projection system has been developed that can effectively expose the fine, demagnified resultant pattern of repeated and non-repeated patterns such as the 256 Mb DRAM on a semiconductor wafer. Particular attention was given to the beam shaping and deflecting optics, which has two stage deflectors for the cell projection beam selection as well as the beam sizing, and three stage deflectors for objective deflection. The cell mask with a rectangular aperture and multiple figure apertures is fabricated by modified Si wafer processes. A new exposure control data for the cell projection is proposed. This data is fitted for the combination of pattern data for the cell mask projection and pattern data for the variable rectangular shape beam within the divided units of the objective deflection. On this exposure system, selective exposure of the desired pattern becomes possible on the semiconductor wafer while a mounting stage of the wafer is being moved, even if the pattern exposure of the repeated and non-repeated patterns is to be carried out. The total overhead time for selecting a subset of multiple figures and a rectangular aperture of the cell mask is less than 5 seconds/wafer. The estimated throughput of this system is approximately 20 wafers/hour.

A vertical magnetoresistive (MR)/inductive head using the current bias technique has been developed for high-density magnetic recording. In this head, the sense current is orthogonal to the air-bearing surface (ABS). The area exposed at the ABS of the MR element is beneath the front lead, and the active area of the sensor is positioned behind that area. The MR element is composed of two permalloy films separated by a thin nonmagnetic material. The easy axis of the films is oriented parallel to the ABS and the films are magnetostatically coupled. The magnetic field created by the sense current is applied in the direction of the easy axis and the MR element is stabilized. In this head structure, no MR-element-stabilizing layer, such as an antiferromagnetic film or a hard magnetic film, is needed. Since the permalloy film beneath the front lead acts as a front flux guide, the signal flux propagates in the sensing area of the MR element behind the ABS. The new vertical MR head has the same electrical performance characteristics as the conventional horizontal MR head. The offtrack signal profile is symmetric against the track center because the magnetization of the two permalloy films rotates symmetrically in the signal-flux direction. The output signal level of this head is independent of the read trackwidth, which favors a narrow trackwidth. The exposed portion at the ABS is only connected to the common lead and is at ground potential. In this design, electrostatic breakdown does not occur and no corrosion is observed. Tests have shown that as the flying height is reduced, the error rate is reduced and noise does not increase. This head structure appears suitable for the near-contact recording of the near future.