KR20190016527A - Method for dividing round planar plate formed of brittle material into a plurality of individual plates by using laser - Google Patents

Abstract

In a method for dividing a circular flat plate (1) formed of a brittle material into a plurality of individual rectangular plates, separation crack (2) is introduced along a predetermined separation line by using laser. A certain method is disclosed to precisely generate the separation cracks (2) and follow the predetermined separation line, wherein the method enables a laser beam to be continuously guided along the separation line in accordance with time and spaces such that the separation crack (2) is started.

Description

TECHNICAL FIELD The present invention relates to a method for separating a circular flat plate made of a brittle material into a plurality of rectangular individual plates by using a laser,

The present invention relates to a method of introducing thermally induced stresses using a laser to divide a flat plate made of a brittle material such as glass, ceramic or semiconductor material into a plurality of rectangular individual plates. The same method of patent classification is described in DE 10 2007 033 242 A1.

It is known that a thermally induced stress can be introduced using a laser to separate the brittle material. To this end, the laser beam is directed along the predetermined separation line towards the surface of the material and is guided along a path of a given separation line to produce a compressive stress. Then, a tensile stress is generated by spraying the coolant to the heated region. If there is a stress difference that exceeds the material's breakdown stress and there is a defect at the beginning of the separation line, the cracking of the material starts from the defect. If such defects are not caused by conventional micro cracks starting from, for example, a mechanical cutting edge, then the initial defects must be created according to the purpose, for example by a diamond cutting wheel or a laser of a suitably focused high energy density do. In the latter case, a machining laser or a second laser may be used. Depending on the internal structure of the material, cracks with intentional depth or cracks completely penetrating through the material can be obtained.

According to the prior art, for example, in order to divide the flat plate into a plurality of the same rectangular individual plates at the time of manufacturing a display screen of a mobile phone or the like or manufacturing a chip, the flat plate is firstly separated along a plurality of first separation lines parallel to each other , And thereafter, the position is changed by a cutting angle of 90 degrees and separated along a plurality of second separation lines parallel to each other. This creates rectangular individual plates defined by the intersection of the separation lines cut at an angle of 90 [mu], and the side lengths of these individual plates are determined by the spacing between the separation lines.

What is important to the quality of the individual plates produced in this way is that the separation cracks are formed exactly along a given separation line.

In DE 10 2007 033 242 A1, it was confirmed that defects of the above quality occurred at the intersections. The separation cracks formed are not perpendicular to each other at the intersections, that is, the progression of the separation cracks has a progression and a deviation of a predetermined separation line in the region of the intersection point. This drawback is due to the mutual influence of the thermally induced stresses along the edges formed by the split cracks and arranged in parallel. This problem is solved by the fact that the strips produced by the separation crack in the first direction are spaced apart.

However, in practice, in the case where the peripheral line of the flat plate has a deviation from the rectangular shape and the separation crack does not vertically touch the circumferential surface, the generated separation crack is a phenomenon in which, at the periphery of the plate to be separated, Shows that there is a deviation.

This occurs especially when the perimeter line is curved. Most importantly, a planar plate having a circular perimeter, such as a wafer disk, which can be individualized into individual chips, is of practical importance. Theoretically, the planar plate may comprise, for example, a triangular shape, an elliptical polygon, or a free-form circumferential surface. In all such cases, at least some of the separation lines are not perpendicular to the circumferential surface.

The problem that arises from this is illustrated in Figures 1A and 1B based on a round flat plate separated along ten separate lines. According to the prior art, as described above, the separation of the flat plate 1 is made along the separation lines 2 arranged in a direction parallel to the diameter of the flat plate 1 and perpendicular to each other. All of the separation lines (2.1 to 2.5) are separated in one direction, then all the separation lines (2.6 to 2.10) are separated in the other direction. All of the separation lines 2 except the dividing line proceeding in conformity with the diameter of the flat plate 1 form a tangent lying on the circumferential surface at the point of cut and an incident angle 留 other than 90 °, As the distance increases, it decreases.

The stress thermally induced by the separation process is applied only to the stress element which diffuses in the direction of the tangent lying at the starting point at the starting point of the dividing line, i.e. the edge region of the plane plate (hereinafter tangent direction) Is critical for the tear opening force of the separation crack along the predetermined separation line, so that the separation crack is formed by bypassing the predetermined separation line as the distance from the diameter increases. In addition, from the critical interval depending on the thickness of the material, scratches and cutting parameters, the crack opening force for starting the separation process is too weak.

Another problem may arise, in particular, when separating into chips with a minimum edge length of less than 1 mm. In the experiment, it was observed that when detached from the edge region, the induced separation cracks were deviated from the predetermined separation line and continuously bent to the other side in the direction of the edge. A possible explanation for this is that the thermally induced stress diffuses symmetrically, perpendicular to the dividing line, with resistances of different magnitudes to the stress depending on the amount of material adjacent to both sides of the dividing line. The crack is bent as the resistance advances in the lower direction.

The present invention provides a method for dividing a flat plate having rectangular and deviated circumferential lines into rectangular individual plates in which thermal stress is induced using a laser, Resulting in the formation of a separation crack that diffuses with high accuracy following the progress of the crack.

This problem is solved by using a laser, in which cracks for dividing a flat plate by thermally induced stress are formed along separation lines arranged perpendicularly to each other at a predetermined interval, and a laser beam directed toward the flat plate is separated at least partially The method comprising the steps of separating a flat plate of a brittle material material into rectangular individual plates in such a manner that the flat plate is separated from the starting point on the circumferential surface of the flat plate in a first step, Two separate straight cracks are generated along these split cracks, and in the second step, the split cracks are introduced along all the dividing lines starting from the starting point at the generated edge and perpendicular to the starting point, respectively, , And in the third step all The separation crack is introduced along a separation line perpendicular thereto, whereby the flat plate is finally divided into a plurality of individual plates.

Advantageously, the separation cracks are introduced in chronological order, each of the separation cracks being introduced in turn along a separation line, the separation line being closest to the half of the edge of the part to be divided into two parts by separation cracks respectively .

In order to shorten the processing time, it is advantageous that a plurality of separation cracks which divide different parts are simultaneously generated in one direction.

To further reduce the processing time, advantageously in the third step, the separation crack can be introduced along the parting line from one edge of the flat plate to the other edge of the flat plate.

It is also advantageous that the portions produced between the individual steps are separated from each other by a stretching process.

Also, the initial defect must be introduced before the separation cracks are introduced at the beginning of the separation line.

More advantageously, a method for separating the circular flat plate can be used. In this case, the first separating line is defined along the diameter, so that the first separating crack divides the circular flat plate in half.

Advantageously, the first separation crack is defined in a direction perpendicular thereto, and all other separation lines are established with a mutual spacing in relation to said separation crack.

Hereinafter, the method will be described in more detail with reference to the drawings.

1A to 1B are schematic views for explaining a cutting method according to the prior art.
2A to 2C are schematic views for explaining a cutting method according to a method according to the present invention.
FIGS. 3A and 3B are planar plates including separating lines to show the order in which the separation cracks are introduced along the separating lines.

The method is described below with reference to a circular flat plate 1. Fig. On the other hand, the method can be used for separating the flat plate regardless of the circumferential shape of the flat plate, and is preferably also suitable for the flat plate whose circumferential line is deviated from the rectangle.

The method is particularly suitable for separating a circular wafer disk into individual rectangular chips.

The introduction of the separation crack is carried out in the same manner as described in the prior art, with the laser beam directed to the surface of the flat plate and guided relative to the flat plate along the predetermined separation line starting from the starting point. This method is crucially distinguished in that it is a separation crack introduction method which is determined according to the order in which the separation cracks are introduced starting from where.

1A shows a circular flat plate 1, wherein the circular flat plate comprises, for example, 10 split lines 2.1 to 2.10. The number of the dividing line is given in the order of how the dividing crack is introduced along the dividing line according to the conventional technique as already described.

Fig. 1b schematically shows the stresses generated according to the above-described prior art method at the starting point of the dividing line, respectively, in order to explain the problem to be solved.

By means of the method according to the invention, the flat plates as shown in Fig. 1A must be divided into a plurality of individual plates by means of separating lines having the same arrangement or the same pattern.

Figs. 2A-2C show a planar plate 1 showing the step-wise introduction of the separation cracks. Only three separate lines are introduced in each direction in order to recognize the figure outline.

3A and 3B show a planar plate 1 including eighteen separation lines in order to illustrate the temporal introduction order of separation cracks along a separation line in one direction in particular.

The basic idea of the method according to the invention is that each separating crack which subsequently defines one of the individual plates should start at the starting point where the thermally induced stress diffuses perpendicularly to the separating crack. This case is reliably provided when the separating line, which should follow with high accuracy, is perpendicular to the straight edge. Further, advantageously, the splitting of the flat plate 1 should be carried out so that at least as much as possible the same amount of material is present on both sides of each split crack at the starting point.

In the first step shown in Fig. 2A, the flat plate 1 is divided into two parts by a split crack, thereby creating two straight edges. Advantageously, said separation is carried out such that the flat plate 1 is split in half. In the case where the flat plate is a circular flat plate, the separation cracks that split in half necessarily coincide with the diameters of the circular flat plates, so that the separation crack proceeds perpendicular to the tangent to the circumferential surface. The stresses occurring at the starting point ideally proceed perpendicular to the dividing line, as do the edges going straight from the straight edge to the dividing line. Then, the two parts produced in the first step fall apart using the drawing method described, for example, in DE 10 2007 033 242. The preferred spacing between the two parts is 5 - 10 탆.

In the second step shown in FIG. 2B, a plurality of separation cracks are introduced along the separation line starting from the two corners generated in the first step, and the separation line proceeds perpendicular to the two corners in the first direction. That is, a crack line having a direction opposite to each other along the dividing line from the center of the flat plate 1 is generated.

Advantageously, firstly, at the beginning of a given separation line, the initial defect is provided, respectively. This can be done mechanically using a diamond or hard metal cutter, or using a laser in a noncontact manner. In the separation process to be carried out next, advantageously, the separation cracks are not introduced in succession along the side-by-side separation line, but splits half of the already generated portions by the separation as far as possible. Advantageously, the first separating line following the introduction of the separating crack in the second step is determined according to the face halves of the two semicircular parts to be produced, starting from the separating line and locating the separating line parallel thereto. The amount of material on both sides of the separation crack is the same over the entire length of the separation crack along the first separation line. All the other separating cracks in the same direction are respectively introduced along the separating line in turn in relation to the respective separating parts, and the separating line is closest to the center of the edge of the part. Thus, at least the amount of material at the beginning of each separation crack is approximately the same on both sides of the separation crack. The process continues until all of the separation cracks are introduced in the first direction along the separation line. This process reduces the difference in material resistance in the direction of the induced stress, and thus ensures that the linear progression of the separation cracks takes place with high accuracy along a given separation line. The result of the second step is that the flat panel 1 is divided into a number of parts, i. E. Strips.

Then, in a third step, the strips are individualized into individual plates, with strips being divided vertically relative to the edges produced.

Advantageously, the initial defect is first provided on a given separation line at the rim of each strip. Possible embodiments may be minimal defects in the border area or continuous scratches over the entire length of the parting line inside the parting line.

After providing the initial defect, advantageously a subsequent stretching process is carried out, wherein the stretching process must prevent contact between the edges during a subsequent separation process.

In the third step shown in FIG. 2C, similar to the second step, all the split cracks are introduced along the split line starting from the generated edge, and the split line proceeds in the second direction. Unlike the second step in which one separation crack is formed along the separation line, a plurality of separation cracks are successively formed along the separation line in the third step, and the separation crack is limited by the straight edge of the strip generated in the second step do. These edges are located exactly perpendicular to the newly created separating cracks. Since the individual plates produced adjacent to the rim of the flat plate do not have a rectangular shape, these individual plates are waste, so the quality of the detached crack defining the individual plates is meaningless. Whether or not the separation crack adjacent to the rim portion follows the progress of the separation line or whether or not the separation crack probably begins is not important. The subsequent separation cracks start again from the edge perpendicular to the separation cracks, so that the subsequent separation cracks again have the required quality.

The separation cracks introduced in the third step may not necessarily be introduced in directions opposite to each other from the center of the flat plate 1 as shown in Fig. 2C, and may be introduced in the same direction from the rim of the flat plate 1 , Which results in even shorter process times.

Thus, in the present method each separating crack that delimits a rectangular individual portion is formed perpendicular to the straight edge at the starting point, except for the initial separating crack, so that the thermally induced stress is reduced by a predetermined progression of the separating crack along the predetermined separating line Lt; / RTI >

All the generated cracks are shown in Fig. 3A, in which case the manner in which the cracks are introduced is indicated by the number of the cracks and the number of cracks (2). 2A-2C, the separation crack introduced in the third step is introduced from the rim of the flat plate 1, as already described here in the same way. The starting points in one direction are represented by squares and the introduction directions of the separation cracks are indicated by arrows, respectively. It is clear that the small number of cracks shown here are for the sake of overview and can actually be many times larger. The split cracks are numbered consecutively according to how the split cracks are sequentially introduced along the split line, in a manner that the number increases. Separation cracks with the same number can be introduced simultaneously, or sequentially, before the later larger number of separation cracks are introduced. Between the three method steps described, there is a need for a relative movement between a cutting tool, a cutting tool, such as a laser beam directed at the surface of the plane plate 1, and a workpiece, such as the plane plate 1, respectively. This means, in the example described, preferably a 90 degree rotation of the plane plate 1 to be machined. A plurality of laser beams can be simultaneously directed to the flat plate 1 in order for the separation cracks to be simultaneously introduced.

1: flat plate
2: Separation crack
2.1-2.10: Separation line

Claims (8)

(2) for dividing the flat plate (1) by using the stress thermally induced by the laser are formed along the dividing lines arranged perpendicularly to each other at a predetermined interval, A method for dividing a flat plate (1) of brittle material into rectangular individual plates, with the laser beam being irradiated being guided at least partly in turn along said separation line,
In the first step, starting from the starting point on the circumferential surface of the plane plate 1, introducing a separation crack 2.1 along a vertical separation line divides the plane plate 1 into two parts, A straight edge is generated along the separation cracks 2.1 at two portions divided by the separation cracks 2.1,
In the second step, in the first step, a plurality of separation cracks (2.2-2.5) are introduced in the vertical direction with respect to each corner at each corner of the two portions divided by the separation crack (2.1) Wherein each of the two portions separated in the step is divided into a plurality of portions, and a plurality of portions divided in the second step are formed with straight edges along respective separation cracks (2.2-2.5)
In the third step, the separation cracks starting from the straight edge (2.6.1-8, 2.7.1) starting from the straight edge along a plurality of separation lines perpendicular to the plurality of separation cracks (2.2-2.5) 6, 2.7.1-10, 2.8.1-4) are introduced, whereby the flat plate (1) is finally divided into a plurality of individual plates. The flat plate of the brittle material is divided into rectangular individual plates Lt; / RTI > The method according to claim 1,
The separation cracks (2-1, 2.2-2.5) (2.6.1-8, 2.7.1-6, 2.7.1-10, 2.8.1-7) introduced into the first, second, 4) are sequentially introduced along each of the dividing lines, and the dividing line is formed at a position corresponding to one half of an edge of a part to be divided into two parts by the dividing cracks. A method for dividing into rectangular individual plates. The method according to claim 1,
The plurality of separation cracks (2.2-2.5) (2.6.1-8, 2.7.1-6, 2.7.1-10, 2.8.1-4) introduced in the second and third steps are introduced simultaneously in one direction Characterized in that the flat plate of the brittle material is divided into rectangular individual plates. The method according to claim 1,
In the third step, the separation cracks (2.6.1-8, 2.7.1-6, 2.7.1-10, 2.8.1-4) are separated from the edge of the flat plate (1) along the separation lines Characterized in that the flat plate (1) is introduced up to another edge of the flat plate (1). The method according to claim 1,
Characterized in that between the first step, the second step and the third step, the resulting parts are separated from each other by a stretching process. The method according to claim 1,
Characterized in that the initial defect is introduced before the introduction of the separating crack (2) at the starting point of the separating line. The method according to claim 1,
Characterized in that the flat plate (1) is a circular flat plate (1) and the parting line in the first step coincides with the diameter of the circular flat plate (1) Method for partitioning. The method of claim 7,
Characterized in that two of the dividing lines perpendicular to each other are aligned with the diameter of the flat plate (1), and the remaining dividing lines are provided so as to be spaced apart from each other with respect to the flat plate A method for dividing a flat plate into rectangular individual plates.

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