JP2003217994A - Method and device for making id code by laser beam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and device for marking an ID code by laser beams which raises productivity by efficiently marking the ID code, without causing increase in the size of the device. <P>SOLUTION: In this method, a stage 2 for mounting an object to be marked 50 and a marking unit 1 disposed above the stage 2 are relatively moved, while laser beams are irradiated on the object to be marked 50 from the marking unit, and a plurality of ID codes 51a are marked in a matrix form of a plurality of rows at a predetermined pitch in the relative moving direction. While the marking unit 1 of one unit moves one pitch in the relative moving direction, the ID codes 51a of the plurality of rows are marked. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser beam identification code marking method and apparatus, and more particularly, to a substrate for exposing identification codes such as history management and quality control to a laser beam in a liquid crystal panel manufacturing process. Relates to a marking method and device for direct engraving.

[0002]

2. Description of the Related Art Generally, in a manufacturing process of a liquid crystal panel, a glass substrate coated with a photoresist (that is, a photosensitive resin) is exposed to a large number of circuit patterns arranged in a matrix by a laser beam pattern exposure device. Then, the identification exposure device exposes the substrate identification code, the panel identification code, and the like, and the peripheral exposure device exposes an unnecessary resist portion on the peripheral portion of the substrate, and then the development processing is performed. The thus-developed glass substrate is divided into units of a plurality of circuit patterns to manufacture a liquid crystal panel.

FIG. 14 shows an example of a glass substrate obtained by developing the exposure process as described above.

On the surface of the glass substrate 50, a large number of liquid crystal panels 51 are arranged in a matrix of 6 × 6 in a matrix and exposed, and a substrate for history management and quality control is provided around the substrate. The identification code 50a is marked. Further, a plurality of liquid crystal panels 51 exposed on the glass substrate 50 are marked with a panel identification code 51a such as an array number so that the individual liquid crystal panels 51 can be identified even after division. For each column, a division board identification code 50b such as division position information is marked so that the division unit can be managed.

When a plurality of small liquid crystal panels 51 are separately manufactured from the large glass substrate 50 as described above, the divided substrate identification code 50b and the panel identification code 51 are used.
a, etc. are required. However, the names, division numbers, etc. of the board identification code 50a, the divided board identification code 50b, the panel identification code 51a, etc. illustrated here are merely examples, and it goes without saying that they may change depending on the type of the liquid crystal panel and the like.

Conventionally, the board identification code 50 as described above is used.
a, divided board identification code 50b, panel identification code 51
The marking method of the identification code such as a is that a marking unit having a laser beam irradiation mechanism is fixed at a fixed position, while the stage holding the glass substrate is moved vertically and horizontally at a constant speed by NC control. The identification code is marked by irradiating a predetermined position on the glass substrate with a laser beam from the laser beam irradiation mechanism of the marking unit.

[0007]

However, in the above-mentioned conventional method, the identification code is scanned and irradiated row by row while the marking unit having the laser beam irradiation mechanism and the stage on which the substrate is placed are relatively moved. However, when the panel is downsized and the number of panels arranged on one substrate is increased, the number of times of scanning irradiation is inevitably increased, which causes a decrease in productivity.

As a measure to prevent this decrease in productivity,
It was considered to increase the number of marking units provided for each marking device, but the increase in the number of the marking devices necessitated a large installation space, resulting in a problem that the device became large.

An object of the present invention is to provide a method and apparatus for marking an identification code by a laser beam, which efficiently marks the identification code without increasing the size of the apparatus and improves productivity.

[0010]

A method of marking an identification code by a laser beam according to the present invention, which achieves the above object, relatively moves a stage on which an article to be marked is placed and a marking unit arranged above the stage. In the method of irradiating the article to be marked with a laser beam from the marking unit while performing the marking, and marking a plurality of identification codes in a matrix of a plurality of rows at a predetermined pitch in the relative movement direction, the one marking unit is relatively It is characterized in that a plurality of rows of identification codes are marked while moving one pitch in the moving direction.

In the conventional marking method, when the marking units are moved relative to each other, the identification codes for each row are marked at a predetermined pitch. Therefore, a laser beam is irradiated from the marking of the identification code to the marking of the next identification code. Not in a blank period. The present invention is
Since the marking unit uses the blank period during relative movement of one pitch to mark plural rows by marking the identification code of adjacent rows, it is possible to perform the relative movement of one pitch relative to the conventional marking method. It is possible to mark more than twice as many identification codes. Therefore, the production amount can be increased without increasing the size of the device such as increasing the number of marking units.

Further, the marking apparatus of the present invention which enables the above-mentioned marking method is provided with a stage on which an article to be marked is placed and a marking unit arranged above the stage so as to be movable relative to each other. Is provided with a laser beam irradiation mechanism for marking a plurality of identification codes on the article to be marked in a matrix of a plurality of rows at a predetermined pitch in the relative movement direction, and the irradiation direction of the laser beam is applied to the laser beam irradiation mechanism. It is characterized in that an angle changing means for changing the moving direction to a direction intersecting with the moving direction is provided.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A detailed description will be given below with reference to the embodiments of the present invention shown in the drawings.

FIG. 1 illustrates a marking device for an identification code by a laser beam according to an embodiment of the present invention.

In FIG. 1, 1 is a marking unit equipped with a laser beam irradiation mechanism, and 2 is a substrate holding stage for holding a substrate of an article to be marked. A photoresist coated substrate 50 is placed on the substrate holding stage 2. The photoresist-coated substrate 50 is configured by coating the surface of the substrate with photoresist, that is, photosensitive resin.

The photoresist coated substrate 50 is carried by a substrate carrying mechanism (not shown) such as a transfer robot or a conveyor and placed on the substrate holding stage 2. The substrate holding stage 2 has a drive mechanism that moves independently in the X-axis direction and the Y-axis direction of Cartesian coordinates, and a rotation drive mechanism that rotates about an axis in a direction perpendicular to the surface center of the stage 2 (both are shown in FIG. (Not shown) is attached so that horizontal movement and rotational movement in the X-axis direction and the Y-axis direction can be performed.

When the photoresist-coated substrate 50 is conveyed to the substrate holding stage 2, the substrate support pins (not shown) are lowered to lower the photoresist-coated substrate 50 onto the substrate holding stage 2 and then the stage 2 is held. It is adsorbed and held by the negative pressure acting on the hole or groove provided in the.

Since the position where the photoresist-coated substrate 50 is placed on the substrate holding stage 2 is not always constant, it is measured how much there is a deviation from the reference position registered in advance. The position measurement is generally performed by a displacement sensor or a CCD camera and a displacement measurement method using image processing, but before holding the photoresist coating substrate 50 on the substrate holding stage 2, it is laterally pressed to a reference position and aligned. You may take

The stage 2 holding the substrate 50 moves to the exposure start position of the identification code based on the data registered in advance by NC control. The exposure start position is registered in advance, and the identification code is exposed with the deviation amount corrected and calculated.

The marking unit 1 splits one laser beam 10 output from a laser light source (not shown) into 11 and 12 by a beam splitter 21, and the straight laser beam 11 changes its angle by a prism 22. The laser beams 12 and 13 whose angles have been changed after branching respectively pass through a beam deflection mechanism 23, and the beam deflection mechanism 23
Laser beams whose angles are changed in time series by
It becomes z. These laser beams 14 to 14z are used for the lens 2
At 4 it is corrected to a parallel beam 15-15z.

Next, the parallel beams 15 to 15z are formed on the substrate 5 by using a light shielding material such as the aperture 25.
To irradiate only a predetermined position of 0, beams in an extra range are processed and cut as shown in FIGS. 2 (A) to 2 (D).

FIG. 2A shows how a laser beam (so-called zero-order light) that is not deflected by the beam deflecting mechanism 23 is emitted. The 0th-order laser beam 14 irradiated without being deflected passes through the lens 24 and becomes the 0th-order laser beam 15 which is shielded by the aperture 25. The aperture 25 does not necessarily have to be arranged downstream of the lens 24 as shown in the drawing, but may be arranged between the beam deflection mechanism 23 and the substrate 50 which is a component to be marked.

2B to 2D show the beam deflection mechanism 2
3 shows how the laser beam (so-called primary light) selectively emitted by changing the beam angle is emitted. When the beam deflection mechanism 23 applies a control signal (not shown) at a certain constant frequency by utilizing the so-called acousto-optic effect, the beam deflecting mechanism 23 causes not to be deflected 0th-order laser beam, but also as shown in FIG. The deflected primary laser beam 14a is emitted. The primary laser beam 14a passes through the lens 24 to become a parallel primary laser beam 15a, and passes through the aperture 25 to become the selectively irradiated primary laser beam 16a.

The deflection angle of the primary laser beam emitted from the beam deflection mechanism 23 changes depending on the frequency of the applied control signal. As shown in FIG. 2C, the primary laser beam 14f deflected and irradiated becomes a parallel primary laser beam 15f by passing through the lens 24, passes through the aperture 25, and is selectively irradiated. It becomes the next laser beam 16f. Further, as shown in FIG. 2D, the primary laser beam 14z deflected and irradiated becomes a primary laser beam 15z which passes through the lens 24 and is blocked by the aperture 25.

From the beam deflecting mechanism 23, in addition to the 0th-order light and the 1st-order light, rays called -1st-order light and 2nd-order light and rays of other modulation components are emitted. There is almost no problem even if it is shielded by 25, shielded by its own housing, or treated as being not emitted due to its weak energy.

The laser beams 16a to 16f that have been selectively irradiated through the aperture 25 are changed in irradiation angle by an optical angle changing means such as a mirror 31. Mirror 3
Laser beams 17a to 17f whose angles are changed by 1
Are focused on the laser beams 18a to 18f by the lens 26 and are applied to the photoresist coating substrate 50 to expose the photoresist. What is called an Fθ lens is generally used as the lens 26, but other lenses may be used, or other optical members may be used in combination.

In the marking device of the present invention, in the above-described structure, the rotating mechanism 32 is attached to the rotating shaft of the mirror 31, and the rotation of the rotating mechanism 32 causes the mirror 3 to rotate.
1 can be tilted with respect to the y-axis direction, and the irradiation direction of the laser beams 17a to 17f reflected by the mirror 31 can be moved in the y-axis direction. Further, another rotation mechanism 34 having a rotation axis in a direction orthogonal to the rotation axis of the rotation mechanism 32 is attached to the L-shaped mounting frame 33 that supports the rotation mechanism 32, and the rotation mechanism 34 is rotated. The laser beam 1 reflected by the mirror 31
The irradiation direction of 7a to 17f can be moved in the x-axis direction.

Rotation mechanism 32 of mirror 31, mounting frame 3
The rotating mechanism 34 of No. 3 constitutes the angle changing means of the laser beam irradiation direction in the present invention. When the rotating mechanisms 32 and 34 are respectively rotated by a slight angle, as shown in FIG. 3, the laser beams 17a to 17f and 18a to 18 are generated.
The irradiation position of f with respect to the substrate 50 can be changed from the position shown by the chain line (the position shown by the solid line in FIG. 1) to the diagonally backward position shown by the solid line.

Next, using the above-described marking device of the present invention, as shown in FIG.
The marking method of the present invention for marking the panel identification code 51a on each of the 12 × 12 (= 144) liquid crystal panels 51 formed in FIG. The identification code is formed of characters and / or two-dimensional figures.

First, in the case of the conventional marking method,
When the stage 2 is moved relative to the marking unit 1 as shown in FIG. 5, since the angle changing means provided in the present invention is not provided, as shown in FIG. Identification code 51
a in the scanning irradiation direction 61 with numbers (1), (2), (3).
.. are selectively irradiated in time series in the irradiation order 62 to expose the identification marks 51a arranged at a constant pitch. In this case, if the marking unit 1 is one unit, it is necessary to perform scanning irradiation 12 times for each row.
If units were provided, it was necessary to perform scanning irradiation 6 times, one row for each unit.

On the other hand, in the marking method of the present invention, by using the angle changing means, as shown in FIG. 6, marking can be carried out every two rows in one scanning irradiation.

That is, when the scanning irradiation is performed once, the substrate 5 is moved by the operation of the angle changing means as described in FIG.
0 laser beams 17a to 17f and 18a to 18
While alternately changing the irradiation position of f to the position shown by a chain line and the position shown by a solid line, two rows of identification codes 51a are marked in the scanning irradiation direction 61 so as to be arranged at a constant pitch (see FIG. 6). . That is, when the sequence number of (1), (2), (3), ... Shown in the irradiation sequence 62 is an odd number, the rotation angle of the angle changing means is set to the posture indicated by the chain line in FIG.
When it is an even number, the rotation angle of the angle changing means is changed to the posture shown by the solid line in FIG. 3 in time series to select the irradiation direction of the laser beam, and the two rows of identification codes 51a are marked at a constant pitch.

In other words, in a row in which the identification codes are arranged in the irradiation order (1), (3) and (5), marking of the identification code of (1) is completed and the identification code of the next (3) is completed. During the blank period before marking starts, the identification code of (2) in the adjacent row is marked, and the marking of the identification code of (3) is finished and the next (5)
During the blank period until the marking of the identification code No. 4 is started, the identification code No. (4) in the adjacent column is marked.
Further, in a row in which the identification codes are arranged in the irradiation order (2), (4), and (6), marking of the identification code of (2) is finished and marking of the next identification code of (4) is started. Until the blanking period, mark the identification code of (3) in the next row, and finish the marking of the identification code of (4) and start the marking of the next identification code of (6). In the blank period, the (5) identification code in the adjacent row is marked.

When the scanning irradiation is performed once in this way, the identification code is marked in units of a plurality of columns.
If two marking units 1 are provided as in the embodiment of the above, the number of scanning irradiations to be performed on one substrate 50 is only three times, and six times when the marking unit 1 is only one. You can do it. Therefore, it becomes possible to perform marking with the number of identification codes which is more than double that of the conventional marking method within the same time.

In the above-described embodiment, the case where the angle of the angle changing means is changed in two steps and two rows of identification codes are marked in one scanning irradiation has been described. However, a blank time between pitches of the identification codes is described. As long as it is allowed, it may be changed in three steps as shown in FIG. 7 or more steps. Further, the focusing lens 26 at this time may be a single lens as shown in FIG. 7, but the focusing lenses 26a, 26b, 26c may be provided at each stage as in the example of FIG. Good. In this case, it goes without saying that the number of lenses 26a, 26b, 26c varies depending on the number of irradiation directions to be changed, and the respective positions can be adjusted by a position adjusting mechanism (not shown).

Further, in the above-described embodiment, the marking unit 1 is fixed in a predetermined position, and the substrate holding stage 2 is moved in the X-axis direction and the Y-axis direction of the orthogonal coordinates and is rotated. However, the marking unit 1 can be reversed in the X-axis direction and Y direction.
It may be configured to move in the axial direction and rotate. Moreover, the marking unit 1 may be only one unit.

Rotation mechanisms 32 and 3 are used as the angle changing means.
Although an example in which 4 are combined is shown, as shown in FIG. 9, for example, a combination of mirror angle changing mechanisms by the galvano scanners 35 and 36 may be used. Further, as the angle changing means, the galvano scanners 35 and 36 may be arranged or combined as illustrated in FIGS. 10 and 11.

Further, the beam deflecting mechanism 23 has been shown as an example of means for branching the laser beam into a plurality of beams. As means for irradiating a plurality of rows of beams, a beam branching element such as a diffractive optical element as shown in FIG. The filter 37 may be used. The laser beam 41 branched by the beam branching filter 37 becomes a parallel laser beam 42 by the lens 24, and each laser beam 4
2 is independently irradiated to the angle changing mechanism 38. The laser beam 43 reflected by the angle changing mechanism 38 becomes a laser beam 44 selectively irradiated by the aperture 25, and the angle of the laser beam 43 is further changed by the mirror 31.
7f. In addition to this, as a means for branching and irradiating a beam, a method using a galvano scanner or a polygonal mirror typified by a polygon mirror, and other means can be used.

Further, in the embodiment, in order to simplify the explanation, the primary laser beams 16a to 16a selectively irradiated in six stages are described.
16f shows the primary laser beam 15z that is shielded. However, in the actual marking, in the case of 9 steps or less as shown in the marking example of FIG. 13, it may be further subdivided into 10 steps or more, and the number of angle switching steps may be any desired number of steps. Needless to say, it does not matter.

In the embodiment, the case where the laser beam 10 is branched into two has been described. However, this may be a case where the laser beam 10 is not branched or a case where a plurality of beam splitters are used to perform multi-branching. . Further, since the beam splitter 21 is a means for splitting a light beam,
Of course, other means such as a half mirror may be used. Further, an example in which two marking units 1 are arranged in parallel is shown, but it goes without saying that the spacing between them can be moved by a moving mechanism (not shown) and the marking location of the identification code can be arbitrarily changed. .

[0041]

EXAMPLE When an identification code is marked on a photoresist substrate with the identification code marking device of FIG. 1, a laser beam having a wavelength λ = 355 nm, which is the third harmonic of a YAG laser, is used as a laser beam and is applied to the substrate. A resin that is sensitive to this wavelength was selected as the photoresist.

Each identification code consists of a grid with a height of 20 dots and a length of 100 dots, and the size of each is 2 mm in height and 10 mm in length. That is, the distance between the respective dot centers, that is, the dot pitch is 0.1 mm.

The pulse frequency f of the laser beam is 60 kHz.
z is set, and the beam changing mechanism 23 deflects and irradiates the beam in the time direction of the identification code in the height direction. At this time, 3 kH is applied in the length direction of the identification code for selective irradiation.
The next pulse will be output at z.

At this time, the moving speed of the stage v = 300 m
If set to m / sec, the dot pitch in the length direction of the identification code is dy = 0.1 mm.

Length Lx = 650 of glass substrate in the long side direction
mm and the length in the short side direction Ly = 550 mm.

As shown in FIG. 4, one glass substrate is vertically and horizontally divided into 12 × 12 pieces, and the length in the long side direction px =
An identification code is marked on each panel having a length of 54 mm and a length py = 40 mm in the short side direction.

When the number of the marking units 1 is 2 in the conventional method, the scanning exposure operation is performed 6 times as shown in FIG. At this time, the identification code to be exposed has a length of 10 mm, and exposure marking is performed in the long side direction of each panel. In this case, the length of 44 mm from the exposure end position to the next exposure start position was the time required for movement.

According to the method of the present invention, 2 during one scanning exposure.
By performing the distribution operation in each direction, a predetermined exposure can be performed by three scanning operations as shown in FIG. Also, FIG.
If the distribution operation to three locations is performed as shown in (3), a predetermined exposure can be performed by two scanning operations. Further, if the number of marking units is increased, the number of scanning operations for each can be reduced.

In any of the above cases, the time when the identification code was not exposed in the conventional method is marked on the adjacent row and / or the other row. Therefore, since the time required for one scanning irradiation is the same, the processing time per substrate can be shortened by reducing the number of times of scanning irradiation, whereby the number of substrates processed per unit time, that is, Throughput can be increased.

The scanning speed v of the substrate and the size of the code shown here are merely examples, and may vary depending on the form actually used. Moreover, the dot-like pattern does not have to be an exact circle or quadrangle; it may consist of triangles, hexagons, other polygonal corners and those with rounded corners, or other geometric figures, or adjacent Recognition as an identification code is possible even when matching dots are connected or independent.

Actually, the energy distribution in the beam is often not uniform, but even in that case, if the energy given to the resist is sufficient, exposure is performed. In addition, due to the actual exposure energy, the sensitivity of the resist, the assembling accuracy of the optical system, the surface reflection, etc., the square may not be a perfect square, but in most cases, there is no problem in the visibility of the identification code.

The various data described in this embodiment are merely examples, and the beam shape can be freely changed to a circular shape, a polygonal shape, or the like by changing the shapes or intervals or combinations of the filters and lenses. Further, the laser beam to be used is not limited to the pulse beam as in the present embodiment, but can be applied to the case of a continuous wave.

In this embodiment, the exposure marking on the photoresist-coated substrate has been described. However, the type of laser used is changed to perform exposure at other wavelengths as well as a metal film-coated substrate, a glass substrate, It is also effective when engraving (direct marking) on a silicon wafer substrate.

[0054]

As described above, according to the present invention, the blank period during which the marking unit relatively moves one pitch is used to mark the identification codes of the adjacent columns to mark a plurality of columns. Therefore, more than double the number of identification codes can be marked during relative movement in the same one pitch as in the conventional marking method.

Further, since it is not necessary to increase the marking unit even if the number of columns to be marked increases, the device does not become large, and the device can be simplified or downsized as compared with the conventional method of marking a plurality of lines. You can

[Brief description of drawings]

FIG. 1 is a schematic view illustrating a marking device according to an embodiment of the present invention.

2 (A) to (D) are explanatory views showing a state of a deflection action by a beam deflection mechanism in the marking device of FIG. 1.

FIG. 3 is an explanatory diagram showing an operation of marking a plurality of rows by the marking device of FIG.

FIG. 4 is a plan view showing an example in which an identification code is arranged on a substrate having a large number of chamfers.

5 is an explanatory diagram showing a scanning irradiation sequence when a panel identification code is exposed on the substrate of FIG. 4 by a conventional method.

FIG. 6 is an explanatory diagram showing a scanning irradiation sequence when a panel identification code is exposed on the substrate of FIG. 4 by the method of the present invention.

7A and 7B are explanatory views showing another example of an operation for performing marking of a plurality of examples by the marking device of FIG.

FIG. 8 is an explanatory diagram showing still another example of an operation of performing marking of a plurality of examples by the method of the present invention.

FIG. 9 is an explanatory diagram showing still another example of the operation of performing marking of a plurality of examples by the method of the present invention.

FIG. 10 is an explanatory diagram showing still another example of the operation of performing marking of a plurality of examples by the method of the present invention.

FIG. 11 is an explanatory diagram showing still another example of the operation of performing marking of a plurality of examples by the method of the present invention.

FIG. 12 is an explanatory view showing still another example of the operation of performing marking of a plurality of examples by the method of the present invention.

FIG. 13 is a marking image diagram of an identification code.

FIG. 14 is a plan view showing an arrangement example of identification codes on a substrate.

[Explanation of symbols]

1 Marking Unit 2 Substrate Holding Stages 10, 11, 12, 13, 14, 14a to 14f, 1
5, 15a to 15f, 16a to 16f, 17a to 17
f, 18a to 18f Laser beam 23 Beam deflection mechanism 25 Apertures 26, 26a to 26c Condensing lens 31 Reflective mirrors 32, 34 Rotation mechanism (angle changing means) 33 Mounting frames 35, 36 Galvano scanner (angle changing means) 50 Photoresist Coating substrate 51 Liquid crystal panel 51a Panel identification code 61 Scanning irradiation direction 62 Identification code irradiation sequence

   ─────────────────────────────────────────────────── ─── Continued front page    (71) Applicant 501230199             Applied Photonics Incorporated             Itted             Applied Photonics, I             nc             Sue, Florida 32826, United States             To 300 Orlando, Research Park             Way 12565             12565 Research Parkwa             y, Suite 300 Orlando,             FL 32826, USA (72) Inventor Kodai Uehara             Toray, 1-41 Oe, Otsu City, Shiga Prefecture             Engineering Co., Ltd. (72) Inventor Seiki Mori             Toray, 1-41 Oe, Otsu City, Shiga Prefecture             Engineering Co., Ltd. (72) Inventor Kenji Sato             Toray, 1-41 Oe, Otsu City, Shiga Prefecture             Engineering Co., Ltd. F term (reference) 2H088 FA24 FA30 HA01 HA18 HA24                       HA28 MA20                 4E068 AB01 CA09 CE02 DA09

Claims (7)

[Claims] 1. A plurality of identification codes are irradiated by irradiating a laser beam from the marking unit while relatively moving a stage on which the article to be marked is placed and a marking unit arranged above the stage. In a matrix pattern of a plurality of rows at a predetermined pitch in the relative movement direction, identification by laser beams marking a plurality of rows of identification codes while the one marking unit moves one pitch in the relative movement direction. Code marking method. 2. The identification code in an adjacent row is marked by changing the irradiation direction of the laser beam to a direction intersecting the relative movement direction while the marking unit moves one pitch in the relative movement direction. A method for marking an identification code with a laser beam according to. 3. The method of marking an identification code with a laser beam according to claim 1, wherein the identification code is formed of characters and / or a two-dimensional figure. 4. The method of marking an identification code with a laser beam according to claim 1, wherein the article to be marked is a photoresist-coated substrate. 5. The method of marking an identification code by a laser beam according to claim 4, wherein the photoresist-coated substrate is for manufacturing a liquid crystal panel. 6. A stage on which an article to be marked is placed and a marking unit arranged above the stage are provided so as to be movable relative to each other, and a plurality of identification codes are relatively moved in the marking unit on the article to be marked. A laser beam irradiation mechanism for marking a matrix of a plurality of rows at a predetermined pitch is provided, and the laser beam irradiation mechanism is provided with angle changing means for changing the irradiation direction of the laser beam to a direction intersecting the relative movement direction. Marking device for identification code by laser beam. 7. The apparatus for marking an identification code by a laser beam according to claim 6, wherein the article to be marked is a photoresist-coated substrate.