JPS5913111B2 - magnetic bubble memory element - Google Patents

Description

[Detailed description of the invention] The present invention relates to improvements in magnetic bubble memory devices.

2. Description of the Related Art Conventionally, magnetic bubble memory elements used in magnetic bubble memory devices include those having an element configuration having odd and even blocks as shown in FIG. To briefly explain this, 1 is a substrate in which a thin film of magnetic garnet is formed by liquid phase epitaxial growth on a non-magnetic single crystal plate of gadolinium, gallium, garnet, etc. A block having a write line 3 with a bubble generator 2, a swap gate or transfer gate 4, a plurality of minor loops 5 for storing information, a replicator 6, a read line 7, a bubble detector 8, etc. is formed through a spacer. has been done. In this block, since the interval between the minor loops 5 is every two bits of the pattern formation upper write line 3 and the read line □, writing and reading are performed once every two cycles of the rotating magnetic field that drives the bubble. Therefore, in a high-density element, two blocks are formed side by side as shown in the figure, and the A block is an odd block and the B block is an even block, and they are operated alternately. Therefore, the length of write line 3 of odd block A is n steps, the length of read line 7 is m steps, and the length of write line 3 of even block B is n+1 steps, and the length of read line 7 is m-. It is considered as one step. In such a bubble memory device, in order to reduce the cost of the photomask by reducing the number of patterns and further improve the yield, the photomask is patterned for only one block of 30, and the actual device is patterned on a wafer. A method is used in which, after repeatedly exposing the top, two adjacent blocks form an odd-even block structure. However, in the device of this method, as shown in Fig. 1, the number of steps from the replicator 6 at the exit 35 of the minor loop 5 to the bubble detector 8 must be shifted by l steps between both blocks. As shown in the figure, the structure of the bubble detector 8 is such that two consecutive detection patterns D1D2 are prepared and odd numbered blocks A1 and even numbered blocks B are selectively used. However, in this method, the resistance deviation between the detectors of both blocks is large and the S/N ratio is extremely poor. As another method, as shown in FIG. 2, dummy detection patterns Ddl and Dd2 are arranged in addition to DlD2, and D1
Noise canceling is sometimes performed in pairs such as Dd and Dd, , D2 and Dd2. In this method, D1 and Ddl
, D2 and Dd2, the resistance deviation is smaller and the S/N is better, but noise (crosstalk noise) due to the stray magnetic field generated by the bubble magnetic domain in front of the detector
may be a problem. The present invention was devised to solve these problems. Therefore, in the present invention, transfer control of the bubble magnetic domain is performed using a soft magnetic material pattern such as permalloy, and a plurality of minor loops for storing information, a pair of read and write lines, and a pattern made of the same material as the transfer pattern are used. In a magnetic bubble memory element that constitutes a bubble memory block and includes a bubble magnetic domain detector that detects bubble magnetic domains by passing a detection current through a soft magnetic pattern having a film thickness and detecting bubble magnetic domains by utilizing the magnetoresistive effect, the bubble magnetic domain The detector is characterized by three consecutive stages of soft magnetic patterns for detecting bubble magnetic domains.

Embodiments of the present invention will be described in detail below based on the accompanying drawings. FIG. 3 shows a block diagram of the block of the embodiment.

In this embodiment, a plurality of minor loops 5 are connected to a write line 3 having magnetic bubble generators 2 and 2a via swap gates or transfer gates 4, and a read line 7 is connected to the minor loops 5 via a replicator 6. A bubble magnetic domain detector 8 is connected to this readout line 7. This bubble magnetic domain detector 8 has soft magnetic patterns Dl and D for bubble magnetic domain detection, which is the main point of the present invention.
2 and D3 are successively formed in three stages. Note that the magnetic bubble generators 2 and 2a are shifted by 1 bit to write line 3.
It is connected to the. The operation of the block constructed in this way will be explained with reference to FIG.

In FIG. 4, two blocks shown in FIG. 3 are formed side by side on the substrate 1, one block A being an odd block, and the other block B being an even block. The program A uses the magnetic bubble generator 2 to set the length of the write line 3 to the swap gate or transfer gate 4 of the +1 minor loop 5 to be n steps, and the read line 7 uses the soft magnetic material pattern of the magnetic bubble detector 8. Connected to D2, the steps from the +1 minor loop replicator 6 to the soft magnetic material pattern D2 are m steps, whereas the block B uses the magnetic bubble generator 2a to connect the swap gate or transfer gate 4 of the ΦO minor loop.
The length of the write line 3 up to n+1 steps, and the read line 7 is the length of the soft magnetic material pattern D of the magnetic bubble detector 8.
Connect to 1, +O minor loop 5 replicator 6
The soft magnetic material pattern D is set in m-1 steps. Therefore, the number of steps from the magnetic bubble generator to the soft magnetic material pattern of the magnetic bubble detector is the same in procs A and B, and writing and reading to the minor loop are performed alternately in procs A and B. It will be. The output of the bubble magnetic domain detector is detected by a detection method as shown in FIG.

In the figure, R1 and R2 indicate the resistances of the soft magnetic patterns forming a pair of each block, and correspond to D2 and D3 in block A shown in FIG. 4, and D, , D2 in block B shown in FIG. Further, R3 is an external resistor, and forms a bridge circuit together with R1 and R2. Detection of bubble magnetic domains by this circuit utilizes the magnetoresistive effect in which R1 or R2 changes when the bubble magnetic domain passes through the detector, and the unbalanced voltage generated in the bridge circuit is detected as an output. The actual output voltage is (R1-
Since it is a differential output proportional to R2), the smaller the resistance deviation of R and R2, the better the cancellation of in-phase noise and the better the S/N. In other words, as shown in FIG. 4, in this embodiment of the side-by-side method in which two adjacent soft magnetic patterns for detection are used as a pair, the resistance deviation due to local variations such as pattern width is small, and the S/N ratio is good. Furthermore, the above-mentioned crosstalk noise canceling is also much better than the conventional system shown in FIGS. 1 and 2. As explained above, the magnetic bubble memory element of the present invention has a good S/N ratio and can reduce crosstalk noise by using soft magnetic field patterns arranged in three stages in its bubble magnetic domain detector. This contributes to improving the reliability of magnetic bubble memory devices.

[Brief explanation of drawings]

1 and 2 are block diagrams of a conventional fused air bubble memory device, FIG. 3 is a block diagram of a magnetic bubble memory device according to an embodiment of the present invention, and FIG. 4 is a block diagram of a magnetic bubble memory device according to an embodiment of the present invention. A block diagram of the magnetic bubble memory element, and FIG. 5 is a circuit diagram of a bubble magnetic domain detection circuit. DESCRIPTION OF SYMBOLS 1...Substrate, 2, 2a...Bubble domain generator, 3...Write line, 4...Swap gate or transfer gate, 5... ...
Minor loop, 6... Replicator, 7...
... Readout line, 8... Bubble magnetic domain detector,
Dl, D2, D3...Soft magnetic material patterns for bubble magnetic domain detector.

Claims (1)

[Claims] 1. Bubble magnetic domain transfer control is performed using a soft magnetic pattern such as permalloy, and includes a plurality of minor loops for storing information, a pair of read and write lines, and a pattern made of the same material as the transfer pattern. In a magnetic bubble memory element which constitutes a bubble memory block and is equipped with a bubble magnetic domain detector that detects bubble magnetic domains by using a magnetoresistive effect by passing a detection current through a soft magnetic material pattern having a film thickness, bubble magnetic domains are detected. A magnetic bubble memory element characterized in that the detector has three consecutively arranged soft magnetic patterns for detecting bubble magnetic domains. 2. A magnetic bubble memory device according to claim 1, characterized in that two bubble memory blocks are combined, one block being an odd block and the other block being an even block. .