JPS6032278B2 - magnetic bubble memory wafer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic bubble memory wafer, and more particularly to a magnetic bubble memory wafer that allows more reliable operation testing of magnetic bubble memory chips cut from a magnetic bubble memory wafer.

BACKGROUND OF THE INVENTION Supported by the remarkable development of electronic technology including semiconductor integrated circuit technology, electronic computers are rapidly becoming smaller and faster.

Furthermore, their reliability has been significantly improved by making the circuit elements solid-state. Furthermore, as the use of electronic computers progresses, the storage capacity of storage devices continues to increase year by year, and there is a strong desire to reduce the units required for storage and shorten access time. In order to reliably store and retain large amounts of information, a highly reliable non-volatile large-capacity memory device is necessary, but it is impossible to achieve this with volatile semiconductor memory, and even though it is non-volatile, Magnetic tape devices, magnetic disk devices, and the like have a fatal flaw in that they have moving parts, and it is difficult to say that these are memory devices that meet needs in terms of reliability.

Magnetic bubbles were invented in view of the above technical background.

- When a bias magnetic field of an appropriate magnitude is applied perpendicularly to the surface of a magnetic thin plate such as garnet or orthoferrite having axial magnetic anisotropy, a cylindrical magnetic domain, a so-called magnetic bubble, is generated.

A device that uses magnetic bubbles to store information, perform logical operations, etc. using magnetic bubbles must be nonvolatile, be an all-solid-state device, have a large capacity, and be relatively fast. For these reasons, its practical application is rapidly progressing in fields that take advantage of these characteristics. In this magnetic bubble utilization device, magnetic bubble generation, transfer,
Various functions such as division, enlargement, detection, and deletion are required.

Furthermore, it is necessary to apply a bias magnetic field to make the magnetic bubble exist safely within the nutritious thin plate, and to apply a rotating magnetic field to move the magnetic bubble within the magnetic thin plate to the base of the magnetic material pattern formed on the magnetic thin plate. shall be. FIG. 1 shows a typical configuration example of a magnetic bubble memory chip used in a magnetic bubble utilization device. The illustrated configuration is a so-called major/minor loop configuration, and in the figure, 1 is a major loop, 2 is a minor loop, 3 is a detector, 4 is a generator, 5 is a replicator, 6 is an annihilator, 7 respectively indicate transfer gates. In the figure, the solid line is a magnetic bubble transfer path formed by a permalloy pattern formed on the slope of the magnetic bubble, and the broken line is a conductive pattern made of gold or the like formed on a thin plate. The operation is performed as follows.

First, a current is supplied in a direction that effectively weakens the bias magnetic field within the loop of the conductive pattern constituting the generator 4 in accordance with the information to be written, thereby generating a magnetic bubble within the loop.

The generated magnetic bubbles are transferred over the major loop 1 by a driving magnetic field rotating in the in-plane direction of the magnetic thin plate, and are aligned by one piece of information (for example, one word) at opposing positions in each minor loop 2. At this time, a current is supplied to the conductor pattern constituting the transfer gate 7 to send the magnetic bubble group on the major loop into each minor loop 2. The magnetic bubble sent into each minor loop 2 circulates within the minor loop 2 due to the driving magnetic field and the storage of serious information is completed. Next, when the magnetic bubble group in each minor loop 2 to be read now reaches a position facing the transfer gate 7, the conductor pattern is energized and transferred onto the major loop 1.

The magnetic bubble train transferred onto the major loop is transferred about m times by the driving magnetic field and reaches the replicator 5. The replicator 5 splits the incoming magnetic bubble into two parts, sends one to the detector 3 along the permalloy pattern, and sends the other one to the major rule.
It is sent to the minor loop again via loop 1. Detector 3
magnifies the magnetic bubbles that arrive one after another in order to increase the detection efficiency, and for example, a change in the magnetic resistance of the magnetic resistance element due to the arrival of the bubbles is read out as a change in voltage. In addition, when deleting the information and writing new information after it has been discussed, the magnetic bubble after division is erased by the annihilator 6 on the major loop, and the new information is written by the generator 4. It's crowded. FIG. 2 is a block diagram of a package that accommodates the magnetic bubble memory chip shown in FIG. 1.

In the figure, 8 is a magnetic bubble memory chip, 9 is a chip mounting plane, 10 is an XY coil for generating a drive magnetic field, 11 is a ferrite yoke, 12 is a thin plate magnet for applying a bias magnetic field, and 13 is a shield case. Triangular wave currents having a phase shift of 90 degrees as shown in FIG. 3A are applied to each of the XY coils for generating a driving magnetic field to obtain a rectangular rotating magnetic field locus as shown in FIG. 3B.

The characteristics of this triangular wave current drive are that the drive circuit is simple, the number of parts is small, and the drive voltage is low. It has various advantages compared to driving using a sine wave current, such as ease of integration. The present invention relates to the above-mentioned magnetic bubble utilizing device, particularly to a magnetic bubble memory wafer for obtaining magnetic bubble chips.

A magnetic bubble memory wafer is a thin disc-like plate made by thinly cutting grown gadolinium, gallium, or garnet crystals.A large number of driving patterns as shown in Fig. 1 are formed on this wafer, and each of them is cut out. This allows a large number of magnetic bubble memory chips to be supplied.

The characteristics test and operation test of the electromagnetic bubble memory chip are
This is done at the wafer stage, where various driving patterns are formed on the surface of the wafer, before it is cut into chips.

That is, as shown in FIG. 4, this type of conventional test is performed by forming a conductor pattern on a wafer 14 for each region of each chip 8 through an insulating layer, as shown by the broken line in FIG. This is done after forming the permalloy pattern shown in the experiment. In the figure, chips 8 of one mother and daughter are cut out from one wafer 14. Now, conventional tests, especially high temperature tests, are conducted as follows. First, after forming the various patterns described above, elongated drive coils 16 and 17 as shown in the figure are arranged so as to cross each other in the chip area to be tested. At this time, a probe card 15 for supplying input signals and control signals to the chip and extracting output signals is connected to each signal terminal at the end of the chip 8 to be tested. Next, the currents of the driving coils 16 and 17 are connected to each other, and the temperature of the chip to be tested is increased using the heat generated by the connecting coils, and a temperature test is performed in this state.The above operations are performed for each chip area. Finish the exam.

However, in this test method, a high heat of, for example, 70 oo is applied to the chip under test as the worst temperature condition, so there is a problem that the probe card 15 or the control circuit system connected to the probe card 15 may be deformed or damaged by the heat. Therefore, in order to prevent damage to the blow card, etc., tests are actually performed while cooling the chip surface by spraying a cooling gas such as nitrogen gas onto it. For this reason, it has the runner-up point of not being able to raise the temperature of the chip under test sufficiently. Furthermore, it is necessary to move the drive coil for each chip under test and position it accurately. Furthermore, there is also the problem that the heat generated by the drive coil is not efficiently propagated to the chip side. Another object of the present invention is to realize a magnetic bubble memory wafer that can raise the temperature to a sufficiently high temperature.A further object of the present invention is to realize a magnetic bubble memory wafer that can heat the chip under test without moving the heat source. Another object of the present invention is to provide a magnetic bubble memory wafer in which a heat source for chip testing can be easily removed without increasing the number of man-hours. The object of the invention can be achieved by forming an energizing pattern on a magnetic bubble memory wafer for heating the wafer by energizing it.

The magnetic bubble memory wafer according to the present invention will be explained below with reference to the drawings.

FIG. 5 is a top view of a magnetic bubble memory wafer according to the present invention.

In the figure, 8 is a magnetic bubble memory chip, 14 is a wafer, 18 is a conductive pattern arranged to orbit around each chip 8, and 19 is an external device for supplying current to the conductive pattern 18. It is a connection terminal. Energization pattern 1
8 is formed on the wafer 14 in the same process as a drive pattern for driving magnetic bubbles, that is, a conductor pattern made of gold or the like that forms a generator, a transfer gate, etc., or forms a magnetic bubble transfer path. It is formed in the same process as forming a permalloy pattern made of permalloy or the like.

As can be seen from the figure, the energizing pattern 18 is connected to the wafer 14.
It is arranged so as to orbit around each chip 8 above.

In the high temperature test, after setting the blow card to the chip under test, a current source (not shown) is connected to the external connection terminal 19, and a current is applied from the current source to the chip under test as much as the heat is generated. Heat the wafer after storage. After that, various characteristic tests were performed by applying current to a drive coil (not shown) to drive the magnetic bubbles inside the chip. It is necessary to place it at a position that does not adversely affect the movement of the magnetic bubble of the chip 18.

In fact, it is preferable to arrange the current-carrying pattern 18 on the scribe line, that is, on the cutting line that is cut when cutting out a large number of chips from the wafer 14. This is because unnecessary conduction patterns after various tests have been performed on the wafer can be electrically disconnected at the same time as cutting out the chips. Of course, if the scribe width is, for example, about 200 French meters, it is possible to form the conductive pattern within that range, and it is also possible to completely remove the conductive pattern from the chip after it has been cut out. As described above, according to the present invention, it is possible to realize a magnetic bubble memory wafer that can be efficiently tested without damaging the test input/output terminal portion of a brochure card or the like.

Further, the current conduction pattern, which is a feature of the present invention, can be formed by the same process as the conventional method without increasing the number of steps, and the effects of applying the present invention are enormous.

[Brief explanation of drawings]

FIG. 1 shows an example of the configuration of a typical magnetic bubble memory chip, FIG. 2 shows an example of the configuration of a magnetic bubble package, and FIG. 3 shows a driving current waveform and a driving magnetic field locus for driving the magnetic bubble. FIG. 4 is a diagram for explaining a conventional magnetic bubble wafer testing method, and FIG. 5 is a top view of the magnetic bubble wafer according to the present invention. In the figure, 8 is a magnetic bubble memory chip, 14 is a bubble memory wafer, 18 is a conduction pattern, and 19 is an external connection terminal. Brother Ding Figure 3 Figure 2 Figure 4 Figure 4

Claims (1)

[Scope of Claims] 1. A magnetic bubble memory wafer, characterized in that an energizing pattern for heating the wafer by energizing is formed on the magnetic bubble memory wafer. 2. The magnetic bubble memory wafer according to claim 1, wherein the energizing pattern is formed at the same time as the magnetic bubble drive pattern formed on the magnetic bubble memory wafer. 3. The magnetic bubble memory wafer according to claim 1, wherein the energization pattern is formed so as to surround each of the plurality of magnetic bubble memory chips formed on the magnetic bubble memory wafer. Magnetic bubble memory wafer. 4. The magnetic bubble memory wafer according to claim 3, wherein the energization pattern is formed on a scribe line when cutting out a plurality of magnetic bubble memory chips from the magnetic bubble memory wafer. memory wafer.