JPH03225940A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To sense a malfunction on the surface of a substrate before a pattern is transferred and to cope with it by sucking the substrate to a vacuum chuck having an uneven part on its surface, measuring the flatness of the entire surface of the substrate, once removing the substrate from the chuck if a nonflat part is sensed, and resucking it after its position is deviated. CONSTITUTION:A substrate 1 is sucked on a vacuum chuck 3 by predetermined conveying means, and secured to a predetermined position on the chuck 3. If a foreign matter 4 exists between the rear surface of the substrate 1 and the protrusion of the chuck 3, a protrusion responsive to the size of the matter 4 is formed on the substrate 1. Accordingly, a chip region different in height from other chip region is formed on the substrate 1. If a protrusion is detected on the substrate 1, a defocusing is eliminated when a pattern is thereafter transferred. The matter 4 for causing the protrusion to be formed on the substrate 1 is contained in the recess of the chuck 3, and the flatness of the substrate 1 is recovered.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a method of adsorbing a substrate to a vacuum chuck that loads and fixes the substrate, and provides a semiconductor device that can detect and deal with abnormalities on the surface of the substrate before pattern transfer. The purpose of the present invention is to provide a manufacturing method, which includes the steps of suctioning a substrate to a predetermined position on a vacuum chuck having an uneven suction surface, and measuring the flatness of the substrate surface, and measuring the flatness of the substrate surface. , the substrate having the non-flat portion is removed from the vacuum chuck, and the substrate is re-adsorbed at a position different from the predetermined position on the vacuum chuck.

[Industrial application field]

The present invention relates to a method for adhering a substrate to a vacuum chuck for loading and fixing the substrate.

With the miniaturization of semiconductor devices in recent years, precise pattern transfer is required during various exposure processes.

For this purpose, it is necessary to horizontally fix the substrate with high precision during exposure, and to flatten the surface.

[Conventional technology]

The conventional method of pattern transfer to a substrate is approximately as follows.

(1) A substrate is sucked onto a vacuum chuck by a predetermined transport means and fixed at a predetermined position on the vacuum chuck.

(2) Since pattern transfer onto the substrate is performed on a chip-by-chip basis, a positioning microscope called an alignment scope is used to accurately position the first chip area.

(3) Adjust the height of the first chip area using a focus sensor.

FIG. 3 is an explanatory diagram showing the principle of the focus sensor, in which IO is a position sensor, 14 is a light source, 11.12 is a mirror, and 13.13a is a substrate surface.

The focus sensor makes light from a light source 14 enter the substrate surface at a predetermined angle, and the position sensor 10 measures the position of the reflected light. As shown in the figure, when light from a light source is irradiated onto a substrate surface 13.13a having different heights, reflected light is incident on the position sensor 10 depending on the height of the substrate surface 13.13a. Since the positions also differ, it is possible to measure the height of the substrate surface based on this.

(4) Perform predetermined pattern transfer in the first chip area.

After this, the same steps as described above are performed in other chip regions as well.

[Problem to be solved by the invention]

However, in the conventional method, if there is a foreign object between the substrate and the vacuum chuck, a convex portion will occur on the substrate surface.
There was a problem that the substrate lost its flatness. When pattern transfer was performed in this state, day focus (out of focus) occurred partially due to the presence of slopes of convex portions on the substrate surface.

Therefore, if day focus is noticed after pattern transfer, it is necessary to remove all the pattern, resist, etc. transferred to the substrate, remove foreign matter, and then perform pattern transfer again. This caused a great deal of effort in the manufacturing process.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a semiconductor device that can detect abnormalities on the surface of a substrate before pattern transfer, and can deal with the abnormalities.

[Means to solve the problem]

In order to solve the above problems, the present invention includes the steps of suctioning a substrate to a predetermined position on a vacuum chuck having an uneven suction surface, and a step of measuring the flatness of the substrate surface. As a result, the substrate having the non-flat portion is removed from the vacuum chuck, and the substrate is re-adsorbed at a position different from the predetermined position on the vacuum chuck.

[Effect]

In the present invention, after a substrate is attracted to a vacuum chuck having an uneven surface, the flatness of the entire substrate surface is measured. If a non-flat portion is detected, the substrate is first removed from the vacuum chuck, the position is shifted, and then the substrate is re-adsorbed.

Therefore, even if a foreign object exists between the back surface of the substrate and the convex part of the vacuum chuck and the surface of the substrate loses its flatness, the present invention detects this and adjusts the substrate so that the foreign object fits into the concave part of the vacuum chuck. Because it is re-adsorbed to the vacuum chuck,
The flatness of the substrate surface can be restored.

Since the pattern is then transferred onto the substrate, the pattern can be accurately transferred onto the substrate at all times in the present invention.

〔Example〕

FIG. 1 is an explanatory diagram showing an example of the present invention in the order of steps,
Reference numeral 1 denotes a substrate, 2 a stage, and 3 a vacuum chuck having an uneven surface, for example, which performs vacuum suction from the protrusions. In this vacuum chuck 3, the interval between the protrusions is, for example, 3Inffl.
The width of the convex portion is, for example, about 1 m. 4 is a foreign object; 5 is a handler equipped with a vacuum suction function for lifting the substrate l from the vacuum chuck 3;

In FIG. 1(a), the reference substrate 1 is sucked onto the vacuum chuck 3 by a predetermined conveying means and fixed at a predetermined position on the vacuum chuck 3.

For example, a focus sensor is applied to measure the entire height of the surface of the substrate 1 on a chip-by-chip basis.

Here, FIG. 2 is an explanatory diagram showing an example of substrate flatness measurement according to the present invention, in which (a) shows a normal state and (b) shows an abnormal state.

If there is no foreign material 4 between the back surface of the substrate 1 and the convex portion of the vacuum chuck 3, the surface of the substrate 1 has a high level of flatness, so that the height of the surface of the substrate 1 is equal to that of the chip as shown in FIG. The units are almost uniform everywhere.

However, if a foreign object 4 exists between the back surface of the substrate 1 and the convex part of the vacuum chuck 3, a convex part corresponding to the size of the foreign object 4 is formed on the surface of the substrate 1, so that Thus, a chip region having a different height from other chip regions is formed on the surface of the substrate 1.

At this time, the following means, for example, is applied as means for determining whether the measured height of the chip region is abnormal compared to other regions.

First, when measuring the height of a chip area on the substrate surface using a focus sensor, all measured values of each chip area are once stored.

The measured value obtained in each chip region is then compared with the average value of the measured values obtained in a plurality of chip regions adjacent to the chip region.

For example, in FIG. 2(b), if the height of the chip area whose height is to be determined is X, and the heights of a plurality of adjacent chip areas are a, b, c, and d, respectively, x - (a +
Calculate b + c + d) / 4 l.

In this embodiment, the standard for determining whether the above-mentioned calculated value is abnormal is, for example, 2 μm.

According to the inventor's data, if the height distribution on the surface of the substrate 1 is within ±2 μm, there is no influence on pattern transfer, etc. performed later.

Therefore, if the calculated value is 2 μm or more, it is determined that a convex portion is formed by the foreign object 4. At this time, the focus sensor applied to the present invention is commercially available, but it has the ability to measure irregularities up to about 0.2 μm, so there is no problem in detecting height differences of 2 μm or more. There is no.

If a convex portion is detected on the surface of the substrate 1 as a result of the above steps, the following steps are performed to prevent day focus from occurring during pattern transfer to be performed later.

Referring to FIG. 1(b), the end of the substrate 1 is vacuum-suctioned by the handler 5, and the substrate 1 is lifted above the vacuum chuck 3.

Next, the stage 2 is moved by about the width of the convex portion of the vacuum chuck 3. For example, since the convex portion of the vacuum chuck 3 in this embodiment has a width of about 1 mm, the moving distance is also about 1 mm.

Since it is normally impossible for the foreign matter 4 to exceed 1 mm in size (foreign matter exceeding 1 mm in size is detected and removed before the substrate 1 is attracted to the vacuum chuck 3). ), by moving the stage 2 by the distance of the convex portion of the vacuum chuck 3, the foreign matter 4 adhering to the back surface of the substrate 1 is moved from above the convex portion of the vacuum chuck 3 to above the fourth portion.

Referring to FIG. 1(C), the substrate 1 which had been lifted by the handler 5 is again sucked onto the vacuum chuck 3 and fixed.

As a result, the foreign matter 4 that caused the formation of convex portions on the surface of the substrate 1 is accommodated in the concave portion of the vacuum chuck 3, so that the flatness of the substrate 1 is restored.

By the way, most of the foreign particles 4 having a size that affects the flatness of the surface of the substrate 1 are removed by prior processing before the exposure process.

Therefore, it is actually almost impossible for a large number of foreign substances 4 to exist on the back surface of one substrate 1 at the same time.

Therefore, as a result of carrying out the above process, instead of flattening the convex portion formed on the surface of the substrate 1 by the specific foreign matter 4, other foreign matter 4 moves onto the convex portion of the vacuum chuck 3, and the convex portion formed on the surface of the substrate 1 is flattened. There is almost no possibility that a new convex portion will be formed on one surface.

If the flatness of the back surface of the substrate 1 is not restored even after performing the above steps, it is assumed that the foreign matter 4 is attached not to the back surface of the substrate 1 but to the convex portion of the vacuum chuck 3. Therefore, in this case, it is effective to notify the person concerned by emitting a warning sound, for example.

Thereafter, a predetermined pattern is transferred onto the substrate 1 on a chip-by-chip basis by a known method.

DESCRIPTION OF OTHER EMBODIMENTS In the vacuum chuck used in the above-described embodiments, vacuum suction was performed from the convex portion of the chuck, but it is of course possible to perform vacuum suction from the concave portion.

Although there is one handler for lifting the substrate in the above embodiment, it is not necessary to use one handler, and a plurality of handlers may be used.

In the above-described embodiment, the stage is moved after lifting the substrate, but this is to move the vacuum chuck, and it is not necessarily necessary to move the stage. Further, at this time, the substrate may be moved instead of the vacuum chuck.

Furthermore, in the above description, the present invention has been explained in correspondence with a substrate exposure process. However, the present invention
For example, the present invention can be applied to other processing steps such as substrate polishing and etching steps that require fixing of the substrate, and is not intended to limit the scope of the present invention.

Although the present invention has been described above with reference to examples, the present invention can be modified in various ways according to the spirit of the present invention, and these are not excluded from the present invention.

[Effects of the Invention] As explained above, according to the present invention, there is an effect that accurate pattern transfer is always possible.

Therefore, day focus does not occur during pattern transfer, and there is no need to redo pattern transfer, which greatly contributes to improving the productivity of related semiconductor devices.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of the present invention in the order of steps, FIG. 2 is an explanatory diagram showing an example of substrate flatness measurement according to the present invention, and FIG. 3 is an explanatory diagram showing the principle of a focus sensor. ■ In the figure, 1゜2゜3゜4゜5゜10゜11゜13゜1. Substrate 1 0. Stage 1 9. Vacuum chuck 1 0. Foreign object 1 3. Handler 1 70 position sensor, 12, mirror, 13a, substrate surface. 3 10th place Sasa ＼ 130 Second unilateral part of the substrate surface focus sensor [Explanatory diagram] Diagram

Claims (1)

[Claims] The method includes the steps of suctioning a substrate (1) to a predetermined position on a vacuum chuck (3) having an uneven suction surface, and measuring the flatness of the surface of the substrate (1). As a result of the measurement, the substrate (1) in which a non-flat portion was present is removed from the vacuum chuck (3), and the substrate (1) is returned to a position different from the predetermined position on the vacuum chuck (3). A method for manufacturing a semiconductor device characterized by adsorption.