JPH09223648A - Method and apparatus for marking semiconductor wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a deep recess by a laser without generating dust. SOLUTION: A semiconductor wafer 21 is mounted on an X-Y table. A plurality of beams 24 having different diameters and coincident centers are emitted from a laser 22 simultaneously or at deviated times. The beams 24 melt and sublimate the surface of the wafer 21 to form a dot-like recess. A plurality of the recesses are aligned and formed to attach a mark such as a symbol or a character to the wafer 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor wafer marking method and marking apparatus.

[0002]

2. Description of the Related Art A semiconductor wafer is provided with a mark for managing and recognizing the semiconductor wafer. This mark
The dots are composed of characters, symbols, and the like that are a set of depressions (dots), and have a size that can be recognized by human eyes.

FIG. 14 shows a semiconductor wafer marked with a mark.
Shows Ha. That is, the mark 10 is attached to the peripheral portion of the semiconductor wafer 11. FIG. 15 shows the depressions (dots) forming the mark. This depression 12
Has a substantially circular shape with a diameter of about 120 μm, and the depth of the depression is about 2 μm. Further, a bulge 13 of about 0.5 μm is formed around the depression 12.

The depressions (dots) 12 are formed on the semiconductor wafer 11 by a laser beam. For conventional marking (formation of depressions), Nd: YAG laser, green
Laser devices such as semiconductor lasers and semiconductor lasers are used.

As described above, the laser beam is used to form a character composed of a set of depressions (dots) in the peripheral portion of the semiconductor wafer,
Marks such as symbols are formed (soft marking), and the semiconductor wafer is managed and recognized by this mark.

[0006]

In recent years, the CMP (Chemical Mechanical Polishing) method has begun to be applied to semiconductor manufacturing processes. The CMP method is a technique in which a film such as an insulating film or a conductive film is formed on a semiconductor wafer and then the film is scraped off to planarize the surface of the film such as the insulating film or the conductive film.

FIGS. 17 to 20 show the state of a mark (a depression) when the CMP method is used a plurality of times in the semiconductor manufacturing process. First, as shown in FIG. 17, an insulating film 14 such as a silicon oxide film is formed on a semiconductor wafer 11. At this time, for example, the recess 12 is filled with about half of the insulating film 14.

Next, as shown in FIG. 18, the insulating film 14 is polished by the CMP method to flatten the surface of the insulating film 14. After that, an insulating film 15 such as a silicon oxide film is formed on the semiconductor wafer 11. At this time, for example, the depression 1
2 is completely filled with the insulating films 14 and 15.

Next, as shown in FIG. 19, the insulating film 15 is polished by the CMP method to flatten the surface of the insulating film 15. In this state, when the insulating films 14 and 15 are films such as a silicon oxide film that transmits light, the recess 12 is formed.
The mark can be recognized even if the mark is completely embedded and the step of the depression is removed.

However, as shown in FIG. 20, if a film 16 such as aluminum which does not transmit light is formed thereafter, it becomes impossible to recognize the mark. As described above, when the CMP method is applied to the semiconductor manufacturing process a plurality of times, the depressions (dots) may be completely filled, and the steps of the depressions may be completely eliminated. In such a case, if a film such as a metal that does not transmit light is formed, the mark cannot be recognized.

In order to solve the above-mentioned drawbacks, the depth of the depressions (dots) forming the mark may be set to be equal to or more than the total thickness of all the films used in the semiconductor manufacturing process. . That is, if the steps of the dents remain after the semiconductor manufacturing process is completed, the semiconductor wafer can be completely managed and recognized.

In recent years, due to the multi-layering of semiconductor devices and the like, the depth of the recess is required to be at least 6 μm so that the step difference of the recess remains even after the semiconductor manufacturing process is completed. .

The conventional marking method is used to form depressions (dots).
It is possible to make the depth of 6 μm or more. That is, it is technically possible to increase the depth of the recess to 6 μm or more by increasing the laser power or using a high output laser.

However, in such a case, there is a drawback that the material of the semiconductor wafer scatters in the peripheral portion of the depression and becomes dust. Further, if the laser power is increased or a high-power laser is used, there is a drawback that the peripheral portion of the depression is significantly raised.

That is, as shown in FIG. 21, when the peripheral portion of the depression 12 is significantly raised, the insulating film 18 in the chip region 17 near the depression 12 is formed by the CMP method.
Surface cannot be sufficiently flattened.

Therefore, as shown in FIG. 22, after the semiconductor wafer is marked, the semiconductor wafer is polished in advance before entering the semiconductor manufacturing process, and the swelling 13 around the recess 12 is formed. Need to be scraped off.

The present invention has been made to solve the above-mentioned drawbacks, and an object thereof is to use a process such as CMP in which a convex portion is scraped off and a film remains in the concave portion. Is a marker attached to the surface of a semiconductor wafer.
It is an object of the present invention to provide a marking method and a marking device that can be recognized by a marker.

[0018]

In order to achieve the above object, a method for marking a semiconductor wafer according to the present invention is a laser method.
The surface of the semiconductor wafer is melted and sublimated by a beam to form dot-shaped depressions, and when a plurality of depressions are arranged to mark a mark or a character, each depression is , A plurality of laser beams having different beam diameters are formed by irradiating the laser beams with their centers aligned and shifted in time.

The method for marking a semiconductor wafer according to the present invention is to melt the surface of the semiconductor wafer with a laser beam,
When a dot-shaped depression is formed by sublimation and a plurality of depressions are arranged to mark a mark or a character, each depression has a plurality of laser beams with different beam diameters.
It is formed by aligning the centers of the beams and irradiating them at the same time.

It is preferable that the powers of the plurality of laser beams are set to the same value. Further, when the plurality of laser beams are emitted from one laser device, the plurality of laser beams are focused by the laser emitted from the one laser device. Is generated by varying.

The plurality of laser beams are generated by dividing the laser irradiated from one laser device into a plurality of laser beams and converting the beam diameter. The plurality of laser beams are emitted from different laser devices.

A semiconductor wafer marking apparatus according to the present invention is an XY table on which a semiconductor wafer is mounted, and the semiconductor wafer is arranged on the XY table by a laser beam. -One or more laser devices for melting and sublimating the surface of the c to form dot-shaped depressions and a plurality of laser beams having different beam diameters are aligned at the same center or simultaneously or temporally. And means for controlling the one or more laser devices so that they are illuminated in a staggered manner.

The semiconductor wafer marking apparatus of the present invention is an XY table on which the semiconductor wafer is mounted, and a laser beam irradiation apparatus arranged on the XY table for irradiating a laser beam. -The laser device and the laser beam emitted from the laser device.
And a means for dividing the frame into a plurality of frames.
A means for converting the beam diameter of each beam and the laser beams having different beam diameters are integrated into one with the centers thereof aligned, and the surface of the semiconductor wafer is simultaneously irradiated. And means for doing so.

When the plurality of laser beams are emitted from one laser device, the beam emitted from the one laser device is changed in focus to change the beam.
It further comprises means for generating a plurality of laser beams having different diameters.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A semiconductor wafer marking method and marking apparatus according to the present invention will be described in detail below with reference to the drawings. FIG. 1 schematically shows a marking device according to a first embodiment of the present invention.

Reference numeral 20 is an XY table. A semiconductor wafer 21 is mounted on the XY table 20.
A laser device 22 is arranged on the XY table 20. The controller 23 controls the operations of the XY table 20 and the laser device 22.

The mark is applied to the semiconductor wafer 21 by irradiating the laser beam 24 while moving the XY table 20 to form a plurality of depressions (dots) on the semiconductor wafer 21. It is formed.

One depression is formed by irradiating the same point with a plurality of laser beams having different beam diameters. That is, one depression is formed under the condition that the beam centers of the respective laser beams coincide with each other.

2 to 7 show each step of the marking method according to the first embodiment of the present invention. First,
As shown in FIGS. 2 and 3, the semiconductor wafer 21 is irradiated with a laser beam 31 having a beam diameter of about 120 μm, and the semiconductor wafer 21 has a diameter of about 120 μm and a depth of about 120 μm. 2μ
A dot-shaped depression 25a of m is formed. At this time, the depression 2
Around the periphery of 5a, a swelling 26 with a height of about 0.5 μm
Is formed.

Next, as shown in FIGS. 4 and 5, a laser beam 32 having a beam diameter of about 80 .mu.m is irradiated to the central portion of the recess 25a so that the semiconductor wafer 21 is recessed into the recess 25a. Dot-shaped depression 25 with a diameter of about 80 μm and a depth of about 2 μm
b is formed.

The depth of the recess 25b from the surface of the semiconductor wafer 21 is about 4 μm. Next, FIG.
And, as shown in FIG. 7, a laser beam 33 having a beam diameter of about 40 μm is irradiated to the central portion of the recess 25b so that the semiconductor wafer 21 has a diameter of about 40 μm and a depth of about 40 μm. Form a dot-shaped depression 25c of about 2 μm.

The depth of the depression 25c from the surface of the semiconductor wafer 21 is about 6 μm. In the first embodiment, the laser beams 31 to 33 have the same power, and only the beam diameters of the laser beams 31 to 33 are different. That is, each laser beam 31 to 3
The power of 3 is set so that the material forming the semiconductor wafer does not scatter when forming the depression, and dust is not generated.

The height of the bulge 26 formed around the depressions 25a to 25c is equal to the height of the first irradiation of the laser beam, that is, about 0.5 .mu.m, which is not a particular problem. However, the protrusion 26 may be scraped off by polishing the surface of the semiconductor wafer 21.

8 to 10 show each step of the marking method according to the second embodiment of the present invention. First, as shown in FIG. 8, a semiconductor wafer 21 is irradiated with a laser beam 33 having a beam diameter of about 40 μm, and the semiconductor wafer 21 has a diameter of about 40 μm and a depth of about 2 μm. Forming a dot-shaped depression 25c. At this time, a bulge 26c having a height of about 0.5 μm is formed around the depression 25c.

Next, as shown in FIG. 9, the beam diameter is about 8
A laser beam 32 of 0 μm is applied to the center of the depression 25c to form a dot-like depression 25b having a diameter of about 40 μm and a depth of about 2 μm, which surrounds the depression 25c of the semiconductor wafer 21.
To form At this time, the bulge 26c in the peripheral portion of the depression 25c is removed, but the bulge 26b having a height of about 0.5 μm is formed in the peripheral portion of the depression 25b.

The depth of the depression 25c from the surface of the semiconductor wafer 21 is about 4 μm. Next, FIG.
As shown in 0, a laser beam having a beam diameter of about 120 μm
Irradiating the central portion of the depression 25b with the column 31 forms a dot-like depression 25a having a diameter of about 120 μm and a depth of about 2 μm, which surrounds the depression 25b of the semiconductor wafer 21. At this time, the bulge 26b in the peripheral portion of the depression 25b is removed, but the bulge 26a having a height of about 0.5 μm is formed in the peripheral portion of the depression 25a.

The depth of the depression 25c from the surface of the semiconductor wafer 21 is about 6 μm, and the depth of the depression 25b from the surface of the semiconductor wafer 21 is about 4 μm.
In the second embodiment, the laser beams 31 to 33 have the same power, and only the beam diameters of the laser beams 31 to 33 are different. That is, each laser
The power of the chambers 31 to 33 is set so that the material forming the semiconductor wafer does not scatter when forming the depression, and dust is not generated.

The height of the bulge formed in the peripheral portions of the depressions 25a to 25c is the amount of irradiation of the laser beam having the largest beam diameter, that is, about 0.5 .mu.m. It doesn't matter. However, this swell may be scraped off by polishing the surface of the semiconductor wafer 21.

In the first and second embodiments, one laser device is used, the beam diameter of each laser beam is changed, and the powers are unified so that the power is about 2 μm. It is adjusted to form a pit of depth.

However, a plurality of laser devices of different types may be provided, and the power of each laser beam may be different. Regarding the power of the laser beam, for example, if the power of the laser beam having the largest beam diameter is set to be small, the bulge formed in the peripheral portion of the depression can be reduced. be able to.

In the above first and second embodiments, three laser beams having different beam diameters are used, but there are two or more laser beams having different beam diameters. do it.
Also, the number of laser beams depends on the semiconductor manufacturing process and laser beam.
It is decided in consideration of the power of the beam.

In the first and second embodiments, a plurality of laser beams having different beam diameters are provided due to the structure of the marking device.
Although the beams are irradiated with a time shift, in the following embodiment, a plurality of laser beams having different beam diameters can be simultaneously irradiated to form the depressions.

FIG. 11 shows the outline of the marking device according to the second embodiment of the present invention. 20 is an XY table. A semiconductor wafer is provided on the XY table 20.
Ha 21 is installed. A plurality of laser devices 22a to 22c are arranged on the XY table 20. The controller 23 controls the operations of the XY table 20 and the laser devices 22a to 22c. 27 and 28
Indicates a half mirror.

The mark is irradiated with a plurality of laser beams from the laser devices 22a to 22c at the same time while moving the XY table 20, and the semiconductor wafer 21 is depressed (dots).
It is formed by forming.

One depression is formed by simultaneously irradiating a plurality of laser beams having different beam diameters on the same point. That is, one depression is formed under the condition that the beam centers of the respective laser beams coincide with each other.

In this embodiment, a plurality of laser beams having different beam diameters can be irradiated at the same point at the same time. However, by using a shutter for cutting off the laser or the like. A plurality of laser beams may be arranged so that they can be irradiated while being shifted in time.

FIG. 12 shows the outline of the marking device according to the third embodiment of the present invention. 20 is an XY table. A semiconductor wafer is provided on the XY table 20.
Ha 21 is installed. A laser device 22 is arranged on the XY table 20. Control device 23
Controls the operations of the XY table 20 and the laser device 22. 27 and 28 are half mirrors that divide the laser beam or combine a plurality of laser beams into one. The beam diameter conversion device 29 is a beam of a laser beam.
It has the function of changing the diameter.

While moving the XY table 20, the mark simultaneously irradiates the laser beam from the laser device 22 and the beam diameter converting device 29, and the semiconductor wafer 21 is dented ( It is formed by forming dots).

One depression is formed by simultaneously irradiating a plurality of laser beams having different beam diameters on the same point. That is, one depression is formed under the condition that the beam centers of the respective laser beams coincide with each other.

In this embodiment, a plurality of laser beams having different beam diameters can be irradiated at the same point at the same time. However, by using a shutter for shutting off the laser or the like. A plurality of laser beams may be arranged so that they can be irradiated while being shifted in time.

FIG. 13 shows a marking method according to the third embodiment of the present invention. This marking method is carried out by using the marking device according to the second and third embodiments.

In this marking method, a plurality of laser beams having different beam diameters and having the same beam center are irradiated at the same time to form a deep recess without generating dust. It is a thing.

That is, the beam diameter is about 40 μm, about 80 μm.
m and about 120 .mu.m of three laser beams 31 to 33 are simultaneously irradiated to the semiconductor wafer 21 with their centers aligned.
As a result, the semiconductor wafer 21 has a diameter of about 40 μm.
Then, a recess 25c having a depth of about 6 μm from the surface of the semiconductor wafer 21, a recess 25b having a depth of about 4 μm from the surface of the semiconductor wafer 21, and a depth from the surface of the semiconductor wafer 21. A depression 25a having a size of about 2 μm is formed at the same time.

At this time, a bulge 26a having a height of about 0.5 μm is formed around the depression 25a. In the present embodiment, the power of the central portion of the three laser beams 31 to 33 is necessarily large, so that deep depressions (dots) can be formed. On the other hand, three laser beams 31
Since the power of the central portion of 33 to 33 is large, scattering of the semiconductor material occurs in the central portion. However, since the scattered semiconductor material is melted by the energy of the laser beam 31 having the largest beam diameter, the scattered semiconductor material does not become dust.

The height of the bulge 26a formed around the depressions 25a to 25c is equal to the height of the irradiation of the laser beam having the largest beam diameter, that is, 0.5.
Since it is about μm, there is no particular problem. However, this swell may be scraped off by polishing the surface of the semiconductor wafer 21.

In this embodiment, the power of the laser beam is
May be the same or different from each other. Further, the number of laser beams may be two or more. The number of laser beams is determined in consideration of the semiconductor manufacturing process and the laser beam power.

[0057]

As described above, according to the semiconductor wafer marking method and marking apparatus of the present invention, the following effects can be obtained. By irradiating a plurality of laser beams having different beam diameters at the same point at the same time or at different times, dust (marks) having a depth that is not completely filled in the semiconductor manufacturing process is dusted. Can be formed without the occurrence of

Therefore, even in the case of applying a semiconductor manufacturing process in which a process in which a convex portion is scraped off and a film remains in a concave portion is frequently used like CMP, the semiconductor wafer is applied.
Marks on the surface of C can always be recognized. Further, even if a deep recess is formed, the swelling of the peripheral portion of the recess (dot) does not become high, so that it does not adversely affect processes such as CMP.

[Brief description of drawings]

FIG. 1 is a diagram showing a marking device according to a first embodiment of the present invention.

FIG. 2 is a plan view showing one step of the marking method according to the first embodiment of the present invention.

FIG. 3 is a sectional view taken along the line III-III in FIG. 2;

FIG. 4 is a plan view showing one step of the marking method according to the first embodiment of the present invention.

FIG. 5 is a sectional view taken along the line VV in FIG. 4;

FIG. 6 is a plan view showing one step of the marking method according to the first embodiment of the present invention.

FIG. 7 is a sectional view taken along the line VII-VII in FIG. 6;

FIG. 8 is a sectional view showing a step of the marking method according to the second embodiment of the present invention.

FIG. 9 is a sectional view showing a step of the marking method according to the second embodiment of the present invention.

FIG. 10 is a sectional view showing a step of the marking method according to the second embodiment of the present invention.

FIG. 11 is a diagram showing a marking device according to a second embodiment of the present invention.

FIG. 12 is a view showing a marking device according to a third embodiment of the invention.

FIG. 13 is a sectional view showing a step of the marking method according to the third embodiment of the present invention.

FIG. 14 is a plan view schematically showing a mark of a semiconductor wafer.

FIG. 15 is a plan view showing a conventional depression (mark).

16 is a sectional view taken along line XVI-XVI in FIG.

FIG. 17 is a sectional view showing one step of a conventional marking method.

FIG. 18 is a cross-sectional view showing one step of a conventional marking method.

FIG. 19 is a cross-sectional view showing one step of a conventional marking method.

FIG. 20 is a cross-sectional view showing one step of a conventional marking method.

FIG. 21 is a sectional view showing a conventional depression (mark).

FIG. 22 is a cross-sectional view showing a conventional depression (mark).

[Explanation of symbols]

 10: Mark (identification number etc.), 11, 21: Semiconductor wafer, 12, 25a to 25c: Dimples (dots), 13, 26, 26a to 26c: Raised, 14, 15, 18: Insulating film, 16: a film which does not transmit light, 17: semiconductor chip region, 20: XY table, 22, 22a to 22c: laser device, 23: control device, 24, 31 to 33: laser beam, 27 , 28: Harmira.

Claims (6)

[Claims] 1. A laser beam melts and sublimes the surface of a semiconductor wafer to form dot-shaped depressions, and a plurality of depressions are arranged to mark a mark or a character. In the marking method, each of the depressions is formed by irradiating a plurality of laser beams having different beam diameters with their centers coincident with each other with a temporal shift. Marking method of Ha. 2. A laser beam is used to melt and sublimate the surface of a semiconductor wafer to form dot-shaped depressions, and a plurality of depressions are arranged to mark a mark or a character. In the marking method, each depression is formed by simultaneously irradiating a plurality of laser beams having different beam diameters with their centers aligned with each other. King way. 3. The plurality of laser beams are one laser beam.
3. The method of marking a semiconductor wafer according to claim 2, wherein the laser irradiated from the laser device is divided into a plurality of pieces and the beam diameter is converted. 4. The method for marking a semiconductor wafer according to claim 2, wherein the plurality of laser beams are irradiated from different laser devices. 5. An XY table on which a semiconductor wafer is mounted, and a dot shape formed by arranging on the XY table and melting and sublimating the surface of the semiconductor wafer by a laser beam. At least one laser device for forming a hollow and a plurality of laser beams having different beam diameters so that they are irradiated at the same time or with a time shift with the centers thereof aligned. And a means for controlling the laser device of 1., a semiconductor wafer marking device. 6. An XY table on which a semiconductor wafer is mounted, a laser device arranged on the XY table for irradiating a laser beam, and irradiation from the laser device. Means for dividing the laser beam into a plurality of laser beams, a means for converting the beam diameter of each of the plurality of divided laser beams, and laser beams having different beam diameters. And a means for irradiating the surfaces of the semiconductor wafer at the same time by aligning the centers of the wafers with each other so that the centers thereof coincide with each other.