JP2001058281A - Scribing method using laser beam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the development of a large-scaled crack at a vertically crossing point of scribed lines. SOLUTION: The scribing method for formation of a vertical crack on a base plate by a thermal strain caused by a radiation of a laser beam upon the base plate of a brittle material is composed of a step in which a vertical crack is formed in a first direction and a succeeding step in which a vertical crack is formed in the direction perpendicular to the first direction. In this step in which the vertical crack is formed in the second direction, the depth of the vertical crack formed in the second direction is made shallower than the depth of the vertical crack formed in the first direction. In the scribing in the second direction, for example, the radiated energy of the laser beam per unit time and unit area is decreased compared to the time of the scribing in the first direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates to a method of forming a vertical crack by thermal strain was irradiated with CO ₂ laser with respect to the brittle material such as a glass plate.

[0002]

2. Description of the Related Art In a process of using a glass cutter wheel to cut a small, predetermined square-sized glass plate from a large-sized glass substrate, a glass plate is scribed in an X direction as a first direction and then scribed in a direction perpendicular to the X direction. Scribing in the Y direction, which is the second direction, is performed, and the wafer is divided by applying a bending stress in a subsequent breaking step.
At the time of the scribe in the second direction, the scribe pressure is increased and the scribe speed is made slower than at the time of the scribe in the first direction to prevent intersection jump.

[0003]

A scribing method using a laser has been put to practical use in place of the conventional scribing method. This scribe method is described in Tokuheihei 8-50.
No. 9947, the vertical cracks obtained by this method are blind. As shown in FIG. 1, a laser beam from a laser 2 is applied to a laser spot 3 on a glass plate 1 moving in an arrow direction A, and a region heated by the irradiation of the laser beam is Next, cooling by the coolant jet 4 causes a change in internal strain stress in the glass plate 1 and a blind vertical crack occurs. This allows blind scribe lines (blind vertical crack lines)
5 is generated. In the description of the present invention, a blind scribe line and a blind vertical crack are described as a scribe (scribe line) and a vertical crack without distinction between a scribe (scribe line) and a vertical crack by a glass cutter wheel.

[0004] In the scribing by the laser, a scribing is performed on a glass plate in a first direction and then a scribing is performed in a Y direction which is a second direction. By the way, in the cross scribe method using a glass cutter wheel, the first scribe in the second direction is performed as described above.
The scribe pressure was increased, the scribe speed was reduced, and the depth of the vertical crack was increased in order to ensure that the vertical crack was deeper than when the scribe was performed in the direction of. Therefore, the laser scribe also follows this method, so that the irradiation energy per unit area per unit time is increased when scribing in the second direction compared to when scribing in the first direction. If the moving speed is reduced or the moving speed is the same, the laser output is increased during scanning in the second direction. However, when the scribe line was scribed in the first direction and the second direction, and then separated, large cracks (cracks in which the product was defective) occurred at a high probability at the points where the scribe lines were orthogonal.

SUMMARY OF THE INVENTION The present invention has been made to eliminate the occurrence of cracks which cause defects at orthogonal portions, and has as its object to provide a new scribing method capable of eliminating cracks which cause defective products.

[0006]

The scribing method of the present invention for irradiating a substrate made of a brittle material of the present invention with a laser to form a vertical crack in the substrate by thermal strain comprises a step of forming a vertical crack in a first direction. Forming a vertical crack in a second direction orthogonal to the first direction. Here, in the step of forming a vertical crack in the second direction, the depth of the vertical crack formed in the second direction is made smaller than the depth of the vertical crack in the first direction.

In the scribing method, preferably, the irradiation energy per unit time per unit time when forming a vertical crack in the second direction is different from that when forming a vertical crack in the first direction. Reduce. In the scribing method, for example, when the relative movement speed of the laser with respect to the substrate is the same in the first direction and the second direction, the laser output in the second direction is reduced with respect to the first direction. Preferably, the laser output in the second direction is reduced by 10 to 40% relative to the first direction. In the scribing method, for example, when the laser output is the same in the first direction and the second direction, the relative movement speed of the laser in the second direction is increased with respect to the first direction. Preferably, the relative movement speed of the laser in the second direction is 110 to 140% with respect to the first direction.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A scribe method according to an embodiment of the present invention will be described below with reference to the accompanying drawings. FIG.
As shown in the figure, the laser beam from the laser 2 is irradiated to the glass plate 1 moving in the direction of the arrow A in the form of a laser spot. By cooling at 4, a change in internal strain stress occurs in the glass plate 1, and a vertical crack occurs due to thermal strain. As a result, scribe lines (vertical crack lines) 5 are generated.

As shown in FIG. 2, the glass plate 1 is scribed in the X direction as a first direction (first-in), and then scribed in the X direction.
Was scribed in the Y direction as a second direction (last insertion) orthogonal to the direction. Here, by performing scribing under various conditions as described later, a scribe line obtained when no abnormality occurs has a vertical crack depth formed in the second direction larger than the vertical crack depth in the first direction. The crack depth was found to be shallow. Specifically, it has been found that the occurrence of abnormalities can be suppressed by reducing the irradiation energy per unit area per unit time when scribing in the second direction as compared with when scribing in the first direction. .

As the scribe conditions, the conditions shown in Table 1 were used. Here, the output of the laser 2 was kept constant, and the moving speed of the laser spot 3 was controlled. As shown in Table 1, in the scribe in the first direction, the output is 30
W, the moving speed is 90 mm / sec, and in the scribe in the second direction, the output is 30 W, the moving speed is 70 mm / sec,
The moving speed at the time of scribing in the second direction is made slower than at the time of the first scribing. In this case, as shown in FIG.
At the intersection 7 of the scribe line 5, a large unnecessary crack 6 was generated on the break surface in the first direction, and the occurrence rate was about 75% (3 out of 4).

Next, as shown in Table 1, the scribe condition is that the output is 30 in the scribe in the first direction.
W, the moving speed is 90 mm / sec, and in the scribe in the second direction, the output is 30 W, the moving speed is 90 mm / sec,
The scribe conditions were the same in the first and second directions.
The incidence of abnormalities in this case is about 25% (1 out of 4)
Met.

Finally, as shown in Table 1 as the scribe conditions, in the scribe in the first direction, the output becomes 3
0 W, the moving speed is 70 mm / sec, and in the scribe in the second direction, the output is 30 W, the moving speed is 90 mm / sec. Thus, the moving speed in the scribe in the second direction is the time in the first scribe. It was faster than that. In this case, no abnormalities were observed.

[0013]

[Table 1]

Next, conditions shown in Table 2 were used as scribe conditions. Here, the moving speed of the laser spot 3 was kept constant, and the output of the laser 2 was controlled. As shown in Table 2, in the scribe in the first direction, the output is 3
0 W, the moving speed is 90 mm / sec, and the scribing in the second direction has an output of 40 W and the moving speed is 90 mm / sec. And made it bigger. In this case, FIG.
As shown in the figure, at the intersection 7 of the scribe line 5, the first
The generation of a large unnecessary crack 6 was observed on the break surface in the direction of, and the occurrence rate was about 75% (3 out of 4).

Next, Table 2 shows the same scribe conditions as in Table 1. At this time, in the scribe in the first direction, the output is 30 W, the moving speed is 90 mm / sec, and the second
In the scribe direction, the output was 30 W, the moving speed was 90 mm / sec, and the scribe conditions were the same in the first and second directions. The incidence of abnormalities was approximately 25% (1 out of 4).

Finally, as shown in Table 2 as the scribe conditions, in the scribe in the first direction, the output becomes 3
0 W, the moving speed is 90 mm / sec, and the scribing in the second direction has an output of 20 W and the moving speed is 90 mm / sec. And made it smaller. In this case, no abnormalities were observed.

[0017]

[Table 2]

As can be seen from the above example, by controlling the output of the laser 2 or the moving speed of the laser spot 3,
At the time of scribing in the second direction, when the irradiation energy per unit area was reduced as compared with the case of scribing in the first direction, a good result that no abnormality occurred was obtained. Typically,
When the relative moving speed of the laser with respect to the substrate is the same in the first direction and the second direction, a good result can be obtained by reducing the laser output in the second direction by 10 to 40% with respect to the first direction. Was. When the laser output was the same in the first direction and the second direction, a good result was obtained when the relative movement speed of the laser in the second direction was 110 to 140% with respect to the first direction. .

[0019]

As described above, the present invention reduces the vertical crack depth formed in the second direction when scribing in the second direction as compared with when scribing in the first direction. In addition, unnecessary vertical cracks can be prevented from occurring.

[Brief description of the drawings]

FIG. 1 shows a laser scribing method

FIG. 2 is a diagram showing scribe line formation in two directions by a laser.

FIG. 3 is a diagram showing the occurrence of an abnormality.

[Explanation of symbols]

 1 Glass plate 2 Laser 6 Crack

Claims (6)

[Claims] 1. A scribing method for irradiating a substrate made of a brittle material with a laser to form a vertical crack in the substrate by thermal strain, wherein: forming a vertical crack in a first direction; Forming a vertical crack in a second direction perpendicular to the vertical direction, wherein in the step of forming a vertical crack in the second direction, the vertical crack formed in the second direction more than the vertical crack depth in the first direction A scribing method using a laser characterized by making the depth shallow. 2. A scribing method using a laser according to claim 1, wherein irradiation energy per unit area is reduced when forming a vertical crack in the second direction as compared with when forming a vertical crack in the first direction. . 3. The laser output according to claim 2, wherein the laser output in the second direction is reduced with respect to the first direction when the relative movement speed of the laser with respect to the substrate is the same in the first direction and the second direction. Scribing method using laser. 4. The scribing method using a laser according to claim 3, wherein the laser output in the second direction is reduced by 10 to 40% with respect to the first direction. 5. The laser according to claim 2, wherein, when the laser output is the same in the first direction and the second direction, the relative movement speed of the laser in the second direction is increased with respect to the first direction. The scribe method used. 6. The laser according to claim 1, wherein a relative moving speed of the laser in the second direction with respect to the first direction is 110 to 140%.
Scribing method using the laser described.