JPS5827914B2 - Bubble memory chip pattern defect repair method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for correcting unnecessary residual defects on a magnetic bubble transfer pattern.

Generally, magnetic bubble memory is made by depositing permalloy to suppress hard bubbles on a single crystal magnetic thin film epitaxially grown on a substrate such as a non-magnetic G-G-G (gadolinium gallium garnet) crystal. A conductive layer consisting of a thin film layer for a magnetic bubble control circuit, a magnetic bubble transfer circuit, etc., and a wiring layer for the above-mentioned circuit group is formed above, with an insulating layer such as silicon dioxide (SiCL) interposed between each layer.

By generating and transferring magnetic bubbles in this soft ferromagnetic thin film pattern, desired information is written, stored, read, etc.

Here, in order to create a fine pattern exclusively for transferring and detecting magnetic bubbles, first a soft magnetic material such as permalloy is deposited by means such as vapor deposition, then photoresist is spin-coated, exposed, and developed. Form a desired photoresist pattern.

Thereafter, the permalloy is etched by ion silling, and then the photoresist is removed by ashing to create a transfer pattern 1 having a TI pattern 2 as shown in FIG.

At this time, unnecessary residual defects 3 as shown in FIG. 1 occur due to various factors.

When this defect occurs, the pattern of this transfer loop cannot be treated as a defective loop, resulting in chip failure.

This is because when the chip is operated as a memory when the chip is completed, unintended magnetic bubbles may be generated due to the above-mentioned defects, resulting in a memory malfunction.

Therefore, conventionally, in order to correct the above-mentioned residual defects,
Generally known techniques such as spot exposure or laser beam are used to correct the pattern so as to make it as close as possible to a normal pattern.

Therefore, when correcting the unnecessary residual defect 3 shown in Fig. 1 by spot exposure, the spot exposure operation must be performed at least 11 times, one in each of the 11 areas indicated by the symbols 1 to 1 in the same figure. was being carried out.

Therefore, there is a drawback that it takes a lot of time to correct the residual defect 3 in the unnecessary portion.

Furthermore, even at present, the gap between the T pattern 2a and the ■ pattern 2b is approximately 1.3 μm, and it is extremely difficult to accurately correct this by spot exposure.

Furthermore, even if a gap is cut in the plate, the gap widens as shown by signal A in FIG. 2, resulting in a defective magnetic bubble transfer margin.

Furthermore, as shown by symbol B in the figure, if the gaps are connected without being cut, this also results in a transfer failure.

Therefore, even if the unnecessary residual defects 3 are corrected, most of the chips end up with poor characteristics.

Furthermore, if the magnetic bubble diameter becomes about 1 μm or less in the future, the gap between the T pattern 2a and the 1 pattern 2b will be about 0.
It has a drawback that it becomes about 5 μm and it is completely impossible to correct it.

Therefore, an object of the present invention is to eliminate the above-mentioned drawbacks, and to provide a method for correcting defects in magnetic bubble transfer patterns, which enables the above-mentioned unnecessary residual defects to be corrected accurately and in a short time. be.

In order to achieve such an objective, the method for repairing defects in magnetic bubble memory chip patterns according to the present invention is based on the premise that they are treated as defect loops, and corrects unnecessary residual defects using a method that is different from conventional methods. It is something.

In other words, all the surrounding parts including the unnecessary remaining part are removed.

The present invention will be explained in detail below with reference to Examples.

Example 1 After removing the fine T-bar pattern for bubble transfer by photoetching and ashing the resist, if an unnecessary portion residual defect 3 as shown in FIG. Perform spot exposure on the enclosed area.

The pattern after etching is removed as shown in FIG.

At this time, this transfer loop and the transfer loops on both sides of it, a total of three transfer loops, become defective loops, but the chip does not become defective, and these three transfer loops are treated as defective loops and made unusable. It is something that

According to such a defect correction method, spot exposure, which conventionally required at least 11 times, can be completed in one time, and the spots can be roughly aligned.
The correction time can be significantly shortened.

Embodiment 2 This method can be applied even when the wafer has already been diced into chips.

That is, a photoresist is applied onto the chip using a spinner, and the area indicated by the dotted line in FIG. 3a is spot exposed.

After that, it is removed by etching to form a structure as shown in Figure 3.

Here, in the above major-minor one-way transfer loop, the minor loop is formed as a backup in case a defective loop occurs for a predetermined number of transfer loops, so this backup Since the loop can be used in place of the defective loop, there is no problem at all in practice.

As is clear from the above explanation, according to the method of the present invention,
Unnecessary residual defects can be corrected accurately and in a short time.

[Brief explanation of the drawing]

Fig. 1 is an enlarged plan view of the main part showing an example of residual defects in unnecessary parts of the transfer pattern of a magnetic bubble memory chip, Fig. 2 is an enlarged plan view of the main part showing an example of pattern correction using the conventional method, and Fig. 3 FIGS. 2A and 2B are enlarged plan views of essential parts for explaining an example of a method for correcting defects in a magnetic bubble memory chip according to the present invention; FIGS. 1...Transfer pattern, 2a...T pattern, 2b...■ pattern, 2...T
I pattern, 3...Remaining defect.

Claims (1)

[Scope of Claims] 1. A method for correcting defects in a magnetic bubble memory chip pattern, characterized in that when correcting an unnecessary residual defect in a magnetic bubble transfer pattern, the entire peripheral portion including the residual defect is removed. 2. Magnetic bubble memo j chip pattern defect correction according to claim 1, characterized in that photoresist is recoated on the magnetic bubble transfer pattern, the peripheral area including the remaining defect is spot-exposed, and then removed by etching. Method.