Texas Instruments Corporation

David C Bullock

Shalendra K Singh

Robert E Fontana, Jr

James Thomas Carlo

Mohammed Sabir Shaikh

John M Bush

Method of fabricating a magnetic bubble memory device in which the magnetizable upper overlay pattern of magnetically soft material, e.g. permalloy, defining bubble propagation elements and bubble function-determining components as located above a bubble-supporting magnetic film is disposed in a wholly planar configuration to avoid bubble propagation anomalies encountered with typical non-planar overlay patterns of magnetically soft material. The fabrication method provides for the consecutive deposition onto a substrate having a magnetic film capable of supporting magnetic bubbles of a layer of non-magnetic electrically conductive material, a layer of insulating material, and a layer of magnetically soft material, such as permalloy. Patterning of the layers then proceeds from the uppermost layer downwardly in stages to form magnetically soft components defining the elements of magnetic bubble propagation paths and magnetic bubble function-determining components as a planar upper overlay pattern from the layer of magnetically soft material, insulation spacers from the layer of insulating material, and control conductors as a planar lower overlay pattern from the layer of non-magnetic electrically conductive material. Patterning of the respective layers is preferably achieved by ion milling of selected portions of the layer of magnetically soft material as defined by a first mask and by sequential plasma etching of selected portions of the underlying layer of insulating material and the layer of non-magnetic electrically conductive material as defined by a second composite mask partially comprising the overlay pattern of magnetically soft material and photoresist material.

Method of fabricating magnetic bubble memory device having planar

Input swap transfer/replicate gate and output replicate gate for use in a magnetic bubble memory arrangement between the bubble storage loops and the input and output sections respectively on opposite sides thereof. The input swap transfer/replicate gate and the output replicate gate are of double level construction, each type of gate including a hairpin element at the first level and mounted on a planar layer of bubble-supporting magnetic material on which bubble propagation elements of magnetically soft material are disposed. The bubble propagation elements are arranged to form propagation paths defining a bubble input section, a bubble output section, and a plurality of closed storage loops defining a bubble storage section interposed between the input and output bubble sections. The second levels of the swap transfer/replicate gate and output replicate gate are situated at the input and output ends of the storage loops, forming the opposite bights of the loop. Each type of gate at the second level comprises an asymmetric hook-like transfer/replicate element whose opposite ends are respectively disposed in the opposite courses of the storage loop of which it forms a bight. The hook-like element includes an intermediate leg portion thereof disposed in overlapping relation to the loop region of the hairpin element, the intermediate leg portion being of wedge-shaped configuration and tapering toward the leading end of the asymmetric hook-like transfer element so as to have a reduced width dimension at the leading end thereof. The wedge-shaped configuration of the intermediate leg of the asymmetric hook-like element is responsible for greater reliability in data transfer and replication as represented by bubbles and the absence of bubbles into and out of the storage loops of the magnetic bubble memory organization.

Swap and replicate gates for magnetic bubble memory

Magnetic bubble domain memory circuit in which magnetizable overlay patterns of magnetically soft material, e.g. permalloy, are provided as bubble propagation elements on a bubble-supporting magnetic layer to define major and minor bubble propagation paths. The major bubble propagation paths provide interchangeable bubble input and output sections, and the minor bubble propagation paths are in the form of closed storage loops providing a bubble storage section comprising first and second pairs of blocks. Bubble generators are provided for each of the blocks included in the first and second pairs thereof comprising the bubble storage section, along with first and second detectors and input/output tracks of bubble propagation elements associated with the respective pairs of blocks of storage loops. Swap transfer/replicate gates are disposed between the input/output tracks and each of the storage loops included in the blocks of storage loops. These gates are alternately operable in a swap transfer mode and a replicate mode so as to simultaneously transfer data as represented by magnetic bubbles and voids from the tracks to the storage loops and from the storage loops to the tracks when operated in a swap transfer mode, and to split respective magnetic bubbles incident thereon in a replicate mode to form a duplicate magnetic bubble in addition to the original magnetic bubble so as to preserve the data intact in the minor storage loop while delivering a bubble to a detector for readout. The first and second bubble detectors are 180.degree. out of phase with respect to each other and are operable during respective halfcycles of a bubble propagation cycle to sense the presence or absence of magnetic bubbles. Thus, respective data bits from different blocks are alternately sensed by the first and second bubble detectors in each bubble propagation cycle to provide a data readout rate twice the field rate.

Block replicate magnetic bubble memory circuit for high speed data

Magnetic bubble domain memory circuit in which magnetizable overlay patterns of magnetically soft material, e.g. permalloy, are provided as bubble propagation elements on a bubble-supporting magnetic layer to define major and minor bubble propagation paths. The bubble propagation elements are arranged to form major propagation paths defining a bubble input section and a bubble output section respectively. A plurality of minor propagation paths in the form of closed storage loops defining a bubble storage section are disposed between the input and output bubble sections, being arranged in even and odd blocks of minor propagation paths. Input swap transfer gates and output replicate gates are provided between the bubble storage loops and the input and output sections respectively. The input swap transfer gates and the output replicate gates are of double level construction, each type of gate including a hairpin element at the first level and a 90.degree. hook-like element at the second level which is correlated into bubble propagation elements included in a minor storage loop. The 90.degree. hook-like elements of corresponding swap transfer and replicate gates are respectively situated at the input and output ends of the minor storage loops, forming the opposite bights of the loop. Bubble generators and detectors are associated with the input and output bubble sections respectively at the opposite ends of the minor storage loops to provide a magnetic bubble domain memory chip for data processing purposes. Data as represented by the presence or absence of a magnetic bubble is transferred into the minor storage loops and replicated outwardly therefrom into the bubble output section for detection in a manner enabling such data to be received by the bubble detector for readout at the field rate.

Magnetic bubble memory circuit with input swap and output replicate gates

Method of providing a substrate with a patterned metal layer disposed thereon, wherein a patterned metal mask is employed in conjunction with ion milling to form the pattern in the metal layer on the substrate. The metal mask as contemplated herein is made of a metallic masking mterial taken from the group consisting of vanadium, tantalum, titanium, and a titanium-tungsten alloy--vanadium being a preferred material because of its resistance to erosion or etching from ion milling coupled with its relatively fast etch rate in a plasma atmosphere. This method has particular application to magnetic bubble domain technology, wherein successive layers of a magnetically soft material, vanadium, and photoresist are deposited on a magnetic film capable of supporting magnetic bubble domain propagation. The layer of magnetically soft material is typically permalloy, and upon being patterned in a selected configuration, defines a bubble propagation path on the magnetic bubble-supporting film. The photoresist layer is selectively exposed to the predetermined pattern by a source of energy, such as an E-beam, X-ray or ultra violet light. The portions of the vanadium layer exposed by the development of the patterned photoresist layer are then plasma etched to form a metal mask of the remaining vanadium layer. The remaining photoresist is then stripped, and the permalloy layer is then ion milled with the patterned vanadium layer serving as the mask. Thereafter, the remaining vanadium layer is removed by subjecting it to plasma etching.

Method of providing a patterned metal layer on a substrate employing

Magnetic bubble domain generator and annihilator for use in a magnetic bubble domain memory device of the major-minor bubble propagation path type. The magnetic bubble domain generator and annihilator structure employs a thin metallic loop which is disposed adjacent to a bubble propagation path and is alternatively operable in both a bubble generation and bubble annihilation mode. A DC bias field is provided to the magnetic bubble domain memory circuit device and exists within the metallic loop of the bubble generator and annihilator structure. Upon applying a current pulse to the thin metallic loop from a pulse generator, the bubble generator and annihilator structure is caused to operate in one of the two possible modes. When the current pulse reduces the DC bias field below a predetermined value, the metallic loop operates as a generator to generate a magnetic bubble. Conversely, when the current pulse raises the DC bias field within the metallic loop above a predetermined value, a magnetic bubble within the loop is annihilated.

Magnetic bubble domain generator and annihilator

Magnetic bubble domain replicator structure as employed in a magnetic bubble domain memory circuit device of the major-minor bubble propagation path type. The magnetic bubble domain replicate structure comprises a thin metallic conducting loop whose opposite sides are in contact with consecutive elements of magnetically soft material (e.g., permalloy) defining a propagation path aligned transversely with respect to a minor bubble propagation path employed for data storage. A DC bias field is provided for the magnetic bubble domain memory circuit and exists within the thin metallic loop of the replicate structure. The occurrence of a current pulse from a pulse generator directed to the thin metallic loop so as to reduce the DC bias field therein below a predetermined value at the same time that a magnetic bubble is within the metallic loop causes replication splitting the magnetic bubble into a pair of bubbles.

Magnetic bubble domain replicator

Magnetic bubble domain memory circuit design in which magnetizable overlay patterns of magnetically soft material, e.g. permalloy, are provided on a magnetic bubble-supporting magnetic layer to define bubble propagation paths including transfer gate elements and combined replicate/transfer gate elements. The replicate/transfer gate elements are operable in two modes either combining the replicate and transfer bubble functions in a first mode or operable to effect a bubble transfer function in a second mode, wherein a magnetic bubble is transmitted from one section of a bubble circuit propagation path to another. Processing of data through the use of the magnetic bubble domains may occur in a first-in/first-out basis in one embodiment and on a last-in/last-out basis in another embodiment of the bubble memory. A pulse generator is associated with the transfer gate and the replicate/transfer gate structures. The pulse generator associated with the replicate/transfer gate elements is controlled to deliver pulses in two different modes for respectively selectively actuating the replicate/transfer gate elements to perform the composite replicate/transfer function or the transfer function alone. The transfer gate elements and the replicate/transfer gate elements are configured to include head portions of pickax shape.

Magnetic bubble domain memory chip with major/minor bubble path

A magnetic bubble domain memory device employing a major row of contiguous regions for major loop bubble travel and a plurality of minor rows of contiguous regions for minor loop bubble travel, wherein the remainder of the magnetic domain-supporting layer in which the respective major and minor rows are provided includes ion-implanted regions. The edges of the ion-implanted regions adjacent the major and minor rows form rails to which magnetic bubble domains adhere and along which they may be propagated. The end region of each minor row is preferably positioned abreast a cusp between regions in the major row to effect zero degree phase transfer. Thin metallic loops are used for bubble generation and annihilation and, with respect to a Permalloy expansion detector, for replication. Metal masking improves the reliability of the boundaries between the non-implanted regions and the ion-implanted regions, especially with respect to the definition of the cusps between adjacent non-implanted regions in a row.

Ion implanted magnetic bubble memory device having major and minor rows

A gapless propagation path structure for magnetic bubbles in a magnetic bubble domain memory system employing permalloy elements, wherein the drive field requirements for the in-plane rotating magnetic field may be reduced for high magnetization materials. An overlay pattern of magnetizable material, e.g. permalloy, is provided on a layer of magnetic material of a type suitable for the propagation of magnetic bubble domains therein. The magnetizable overlay pattern includes respective magnetizable elements forming the propagation paths for the magnetic bubble domains, the elements being so arranged as to provide a continuous track of magnetizable material included in the magnetizable overlay pattern, thereby defining a gapless propagation path for the magnetic bubble domains. The in-plane rotating magnetic field within the plane of the magnetic layer on which the magnetizable overlay pattern is disposed causes magnetic bubble domains to travel along respective gapless propagation paths included in the magnetic bubble domain memory system, there being respective movement-controlling elements associated with the gapless propagation paths for maintaining the magnetic bubble domains in motion along the selected bubble propagation path therefor.

Gapless magnetic bubble propagation path structure

A magnetic bubble detector utilizing a thin film optical waveguide. Light is optically coupled into the guide for propagation of linearly polarized light along a first axis thereof. Magnetic bubbles from a memory storage location are moved past the sensor on a second axis transverse the first. A sensor is provided for sensing changes in the polarization mode of the light propagating along the axis of the waveguide. The sensor includes an optical device for coupling light out of the waveguide. The passage of a magnetic bubble along the second axis past the waveguide will modulate the polarized light by the fringing field of the bubble and provide a light output signal from the sensor indicating the passage of each bubble.

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Dallas, TX, United States of America

David C Bullock