Abstract: A magnetic bubble detector which includes chevron propagation elements and underlying thin film magnetoresistive members is described. A portion of the dummy detection member is misaligned from its overlying chevrons. This misalignment provides a bias to the detection circuitry. A negative voltage is detectable when no bubble is present and a positive potential when a bubble is present. This allows easy matching between the detector and sense amplifier.

Abstract: A process for removing a liquid phase epitaxial layer of material from a wafer substrate is disclosed. An etch melt is provided which is substantially the same as that used to grow the epitaxial layer on the wafer surface. The temperature of the etch melt is adjusted such that it exceeds an equilibrium temperature of the epitaxial layer, and lies below an equilibrium temperature of the substrate, such that the epitaxial layer is etched away without affecting the substrate material. The wafer is immersed and maintained within the melt until the epitaxial layer is removed. The wafer may then be reused without repolishing.

Abstract: A process is described for removing the rounded regions in a silicon dioxide layer particularly in a layer covering conductive members. The silicon dioxide layer is subjected to ion milling. The angle of incidence of the ions striking the rounded regions is greater than the angle of incidence in other regions of the layer. This causes more of the rounded regions to be removed, thereby providing a smoother, faceted surface. The process eliminates the need to taper the edges of the conductive members as done in the prior art.

Abstract: A magnetoresistive bubble detector which includes an expander, a first and second detector element and a dummy element is disclosed. An expanded bubble is propagated from the first detector element to the second detector element. The detectors are coupled in pairs with the first element of one detector and the second element of the other detector connected in a bridge circuit with the dummy elements. Two independent streams of spaced-apart bubbles are detected within the bridge circuit.

Abstract: A method for adjusting output signal levels from a magnetic bubble detector. Portions of the chevron stacks located adjacent to either the detector element or dummy element are selectively removed. This removal changes the magnetic field at either one of these elements, thereby adjusting the detector output. This removal may be performed with laser trimming techniques or by etching.

Abstract: An improved magnetic domain generator for a magnetic arrangement employing a layer of garnet in which single wall domains (bubbles) are moved by an in-plane rotating magnetic field. A first domain generator includes a first propagation circuit for moving bubbles away from the generator when the rotating field is in a first direction. A second domain generator includes a second propagation circuit for moving bubbles away from the second generator when the rotating magnetic field is in an opposite direction to the first direction. The two generators are coupled to a common pulse source which is able to provide pulses at twice the rate of rotation of the magnetic field. In this manner, two independent streams of bubbles may be produced by the generators from a single pulse source.

Abstract: A process for thickening the relatively thin bonding pads of a single wall magnetic domain (bubble) device is disclosed. The process is particularly suited for thickening the pads defined by a buried metal layer, such as the conductive layer often disposed between the magnet garnet layer and permalloy layer. Windows are etched through a polyimide scratch protection layer to expose underlying bonding pads. A layer of gold is formed over this protective layer and over the exposed pads. The gold layer is washed away from the protective layer. Since the gold adheres only to the bonding pads, it remains to build up the thickness of these pads.

Abstract: An error repairing method and apparatus for a magnetic bubble memory for restoring stored binary data to its original form are described. The method and apparatus are employed to compensate for random error in bubble memories resulting from slipped or disappeared bubbles. The data is coded with an error correcting code, such as a Hamming or Fire code, before storage. The stored, coded data is periodically read from memory and errors are detected and corrected. The corrected, coded data is rewritten into memory. In one embodiment the frequency of the repair cycles is a function of the rate at which errors are detected.