JPS6160501B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in methods of making magnetic bubble memory devices.

As the manufacturing technology and materials of magnetic bubble memory devices progress, the storage capacity of magnetic bubbles (hereinafter referred to as bubbles) stored in one device increases over the years, while the diameter of the bubbles serving as the storage medium decreases. Alternatively, conductive patterns made of Ni--Cu alloy and transfer patterns made of permalloy are becoming smaller.

For example, in the case of a memory element with a storage capacity of 1M bits, the minimum pattern size is about 1 .mu.m, and the entire pattern of the electronic circuit is formed on a 10 mm square magnetic garnet crystal film.

Regarding this, the pattern forming method currently used is that when using a high-performance projection exposure machine, the possible transfer area is 10 mm square, but in consideration of yield due to resolution etc., a central part with good resolution is used. Expose 5x10mm pattern area twice to 10mm
A corner circuit pattern is formed and used as one element.

In the current circuit configuration using the block replicate transfer method, the right and left sides have different configurations to speed up access time, and the bubble signal corresponding to the input information is divided into an even number column and an odd number column and processed. A method is being adopted.

FIG. 1 is a schematic diagram of an exposure mask for forming a conventional permalloy pattern circuit, which obtains a write major line 2, a minor loop 3, a read major line 4, a bubble detector 5, etc. with generator forming ends 1a, 1b. The pattern shape is actually composed of T-patterns, half-disk patterns, etc. arranged in a row.

The feature of this exposure mask pattern is that the writing measure line 2 has two generator forming ends 1a and 1b, and the detector 5 is also composed of three permalloy detection elements 5a, 5b, and 5c in the shape of a fishbone or serpentine, including a dummy. It is being formed.

Figure 2 shows the configuration of a 1M-bit bubble memory device using this mask pattern, moving the wafer by 5 mm and performing projection exposure twice to create two 500K-bit memory patterns and adopting an odd-even circuit configuration. It is a diagram.

In this memory element, an insulating film is first deposited on a wafer on which a magnetic garnet single crystal has been produced, and then a conductive pattern for bubble control is formed on the surface of the insulating film by photoetching. Create patterns 1c and 1d. Thereafter, an insulating film is deposited on the conductive pattern, and a permalloy pattern is formed on the conductive pattern using the exposure mask shown in FIG. 1, thereby manufacturing the semiconductor device.

In the figure, 1 and 1' are the ends 1a and 1b of a writing major line 2 made of a permalloy pattern.
These are two bubble generators formed by overlapping conductor patterns 1c and 1d. Pattern 6 on the left is an odd block that processes and stores odd columns of bubble signals, and pattern 7 on the right is an even block that processes and stores even examples.
The circuit configuration of the element is taken.

That is, in this circuit having a major/minor configuration, a large number of minor loops 3 and 3' are arranged at every other bit of the transfer pattern constituting the major lines 2 and 2'. When writing the bubble signal, the bubble signal is propagated on the gear lines 2 and 2' by the driving magnetic field, but at this time, the odd-numbered bubbles making up the bubble signal correspond to the minor loop 3 of the odd-numbered block 6. At the same time, the even-numbered bubbles are transported to the respective bit positions of the major line 2' corresponding to the minor loops 3' of the even-numbered blocks 7.

Thereafter, in this state, each bubble on the major lines 2 and 2' is transported all at once to each minor loop 3 and 3' by the action of a transfer gate made of a conductor pattern (not shown), and writing is performed.

Here, generators 1 and 1' of even and odd blocks that generate bubble signals are operated by the same power supply to simplify the drive circuit, but in this case, in order to perform the above writing, generators 1 and 1' It is necessary that the number of bits in the transfer paths leading to write major lines 2 and 2' differs by one bit between odd block 6 and even block 7. This can be done by using two generators separately. It is being said.

That is, as shown in Fig. 2, the generator 1 on the right side is used in the odd block 6, and the generator 1' on the left side is used in the even block 7, and both are connected by external electrode terminals 8, 8' connected to the drive circuit. This changes the number of bits sent from generators 1, 1' to major lines 2, 2' by 1 bit.

The same thing needs to be done during readout, and this is achieved by using detection elements 5a, 5b, and 5c that are adjacent to each other with a one-bit difference in the detector 5.

This is because, as shown in FIG. 2, in the odd block 6, the bubble signal from the readout major line 4 is taken out by the inner detection element 5a, while in the even numbered block 7, the bubble signal from the readout major line 4 is taken out from the center detection element 5b. A 1-bit difference is achieved.

The reason why the dummy detection elements 5b for the odd block 6 and the dummy detection elements 5c for the even block 7 are required is that the bubble signal is detected by a differential amplifier with high detection efficiency. The signals from the dummy detection elements 5b and 5c are sent to one terminal of the differential amplifier, and the detection signals from the detection element 5a of the odd block 6 and the signals from the detection element 5b of the even block 7 are sent to external electrode terminals 9 and 9. ' becomes a continuous signal and is connected to the other terminal of the differential amplifier.

In the bubble memory device using the conventional pattern forming method described above, there are some differences in characteristics between even-numbered block detectors and odd-numbered block detectors because the positional relationship of the detection elements used is slightly different, and there are also differences in characteristics. It requires a generator and a detection element, which is disadvantageous in terms of pattern density, and moreover, it is easy to make mistakes when bonding the generator and detection element used and their external electrode terminals, resulting in a malfunctioning element due to incorrect connection. There were problems such as the possibility that

As a countermeasure to this problem, the present inventor has already proposed the following method. In this method, exposure is performed using an exposure mask as shown in FIG. This exposure mask is a mask through which light passes for obtaining a writing major line 10 having one generator-forming end 10a, a reading major line 11, a minor loop 23, and a bubble detector 24 having two detection elements 24a, 24b. It has a pattern. Also, main pattern 1 in which mask patterns 10, 11, 23, 24 for obtaining each of these functional elements are located.
The major lines 10 and 11 in 4 have variable pattern areas 12 and 13, and the main pattern area 14
Sub-pattern regions 15 and 16 are formed above and below on both sides. The four partial views A, B, C, and D shown around FIG. 3 are variable pattern areas 12, 1.
3 and the sub-pattern areas 15 and 16. In the sub-pattern areas 15 and 16 of Figs. A mask pattern is formed through which light passes through, but in order to obtain one permalloy pattern corresponding to 1 bit, the mask pattern is made by forming 15a and 16a, which are 1/2 the size.
Unit patterns 15b and 16b for obtaining two permalloy patterns corresponding to 2 bits are arranged in parallel. In addition, the variable pattern areas 12 and 13 in Figures A and B are mask patterns 10b and 11a for 2 bits (2 bits) through which light passes to obtain a half-disk-shaped permalloy pattern for transfer forming the major lines 10 and 11 as shown in the figure. The area corresponding to two permalloy patterns is provided as a region that does not transmit light. When performing projection exposure while moving the wafer by a fixed distance left and right using this exposure mask, by repeating the operation of changing the moving distance slightly more than the fixed distance every other time, the variable pattern areas 12 and 13 are One or two unit patterns 15a, 15b, 16a, 16b can be selectively projected to obtain a half-disc-shaped permalloy pattern in the sub-pattern regions 15, 16. In this way, it is possible to continuously pattern the major lines 10 and 11 having different numbers of constituent bits.

However, in this case, since the gap part of the half disk is used to connect the patterns, errors in step feed between adjacent elements appear as variations in the gap width of the gap, and this is the cause of deterioration in bubble propagation performance. There is a drawback. The present invention has been devised to improve this drawback.

Therefore, in the present invention, a bubble propagation path in which a plurality of permalloy patterns are arranged in a row is formed on a magnetic bubble memory substrate by metal vapor deposition or sputtering and photoetching, and during the photoetching. an exposure method in which a circuit forming mask pattern created on an exposure mask is transferred to a photosensitive material coated on the substrate by a projection exposure machine at least twice by moving the substrate by a predetermined amount; A main pattern area in which a mask pattern is formed, at least one variable pattern area formed in the main pattern area that does not transmit light, and a predetermined pattern in the variable pattern area located near the main pattern area. and a sub-pattern area for providing a driving pattern, and within the sub-pattern area there is a driving pattern forming a lower end of the permalloy pattern, a driving pattern forming an upper end of the permalloy pattern, and a gap between the upper and lower driving patterns. a first pattern row including drive patterns that form an even number of the permalloy patterns; a second pattern row that includes the upper and lower drive patterns and a drive pattern that forms an odd number of the permalloy patterns between the drive patterns; a driving pattern forming a lower end of the permalloy pattern connected to the upper end driving pattern, and a driving pattern forming a lower end of the permalloy pattern connected to the upper end driving pattern; an exposure mask on which a driving pattern forming an upper end of a permalloy pattern is formed; and when the substrate is moved and transfer exposure is performed, the variable pattern area in the main pattern area and the sub pattern are exposed during adjacent exposure. The regions overlap on the substrate, and a predetermined pattern row is selected from among the first and second pattern rows of the sub-pattern region within the variable pattern region according to the amount of movement of the substrate, and the main pattern The driving pattern of the upper end or the lower end formed in the region and the driving pattern of the lower end or the upper end formed in the sub-pattern are exposed in parallel so that they overlap slightly at the connecting part. This makes it possible to selectively form a bubble propagation path having a Permalloy pattern of even number bits or odd number bits using one type of exposure mask.

The method of the present invention will be explained in detail below based on the accompanying drawings. FIG. 4 shows the main parts of a mask for carrying out the method of the present invention. Figure A in the figure is the main pattern area,
Figure B shows the sub-pattern area, with reference numerals 25 and 26.
27 is a drive pattern for forming the upper and lower ends of the propagation path permalloy pattern formed in the main pattern area, 28 to 3 are variable pattern areas;
4 is a driving pattern for forming a permalloy pattern for a propagation path in the sub-pattern region. The drive patterns 25 and 26 in the main pattern area A are each cut within the drive pattern by the variable pattern area 27. Also, sub pattern area B
There are two pattern rows: a lower end drive pattern 28 and an even number (two in the embodiment) of drive patterns 2.
9, 30, a row of lower end drive patterns 31, a lower end drive pattern 32, an odd number (one in the embodiment) of drive patterns 33, and a row of lower end drive patterns 34 are formed. Note that the drive pattern 33 in the latter pattern row is twice the size of the drive patterns 29 and 30 in the former pattern row, and has one bit smaller. Furthermore, the drive patterns 28, 31 and 32, 34 at the ends of both pattern rows are each cut within the drive pattern by a sub-pattern region. However, this drive pattern is cut so that it slightly overlaps the drive patterns 25 and 26 in the main pattern area A when the variable pattern area 27 and the sub-pattern area B are overlapped.

Next, an exposure method using the mask formed in this manner will be explained. First, a substrate coated with a photosensitive material is placed on a moving table of a projection exposure machine, and the main pattern area A of the mask is projected onto the photosensitive material. Next, the substrate is moved by a predetermined amount and the sub pattern area B is projected onto the variable pattern area 27 portion where the main pattern area was projected. At this time, if the substrate is positioned so that the drive patterns 25 and 26 in the main pattern area are connected to the drive patterns 28 and 31 in the sub-pattern area B, a propagation path as shown in FIG. 5a is formed, and the main pattern area driving pattern 25 in the area,
If the substrate is positioned so that the drive patterns 32 and 34 of the sub-pattern area B are connected to the drive patterns 26, a propagation path with one bit less than that shown in FIG. 5A is formed by exposure as shown in FIG. 5B. In this way, an element similar to that shown in FIG. 3 described above can be patterned.

An advantage of the method of the present invention as described above is that there is a greater tolerance for errors in substrate feeding accuracy caused by a projection exposure machine during photolithography exposure. 6th
The figure shows the state of the drive pattern when the deviation of the sub-pattern area from the main pattern area is zero and when the deviation is 0.5 μm in the X or Y direction. It has been confirmed that there is no adverse effect on bubble transfer up to the deviation of .

As explained above, the method for producing a magnetic bubble memory element of the present invention can selectively form bubble propagation paths for even-numbered bits and odd-numbered bits by using only one type of exposure mask. This contributes to improving the reliability of the magnetic bubble memory device by allowing a large error tolerance and forming a bubble propagation path with a stable bubble transfer function.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a mask pattern used for forming a conventional magnetic bubble memory element, FIG. 2 is an example of conventional circuit formation using this pattern, and FIG. 3 is an explanatory diagram for explaining a conventional exposure method. FIG. 4 is a diagram of a pattern configuration of a mask for carrying out the method for producing a magnetic bubble memory element according to the present invention, FIG. 5 is a diagram of a pattern configuration formed using the mask of FIG. 4, and FIG. 6 is a drive pattern. FIG. 3 is an explanatory diagram showing the state of the connection part. A...Main pattern area, B...Sub pattern area, 2
5, 26, 28-34... Drive pattern, 27... Variable pattern area.

Claims (1)

[Claims] 1. A bubble propagation path in which a plurality of permalloy patterns are arranged in a row is formed on a magnetic bubble memory substrate by metal vapor deposition or sputtering and photoetching, and during the photoetching, an exposure method in which a circuit forming mask pattern created on an exposure mask is transferred to a photosensitive material coated on the substrate by a projection exposure machine at least twice by moving the substrate by a predetermined amount; A main pattern area in which a mask pattern is formed, at least one variable pattern area formed in the main pattern area that does not transmit light, and a predetermined pattern in the variable pattern area located near the main pattern area. and a sub-pattern area for providing a driving pattern, and within the sub-pattern area there is a driving pattern forming a lower end of the permalloy pattern, a driving pattern forming an upper end of the permalloy pattern, and a gap between the upper and lower driving patterns. a first pattern row including drive patterns that form an even number of the permalloy patterns; a second pattern row that includes the upper and lower drive patterns and a drive pattern that forms an odd number of the permalloy patterns between the drive patterns; a driving pattern forming a lower end of the permalloy pattern connected to the upper end driving pattern, and a driving pattern forming a lower end of the permalloy pattern connected to the upper end driving pattern; an exposure mask on which a driving pattern forming an upper end of a permalloy pattern is formed; and when the substrate is moved and transfer exposure is performed, the variable pattern area in the main pattern area and the sub pattern are exposed during adjacent exposure. The regions overlap on the substrate, and a predetermined pattern row is selected from among the first and second pattern rows of the sub-pattern region within the variable pattern region according to the amount of movement of the substrate; The driving pattern at the upper end or the lower end formed in the pattern area and the driving pattern at the lower end or the upper end formed in the sub-pattern are exposed so that they overlap slightly at their connection parts, respectively. A method for producing a magnetic bubble memory element, characterized in that a bubble propagation path having a permalloy pattern of even number bits or odd number bits can be selectively formed using one type of the exposure mask.