JP2008168304A - Laser cutting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser cutting method by which the shape of a chip-size substrate is not distorted even when forming recessed parts being starting points on a strip-shaped slave substrate to be worked after primary cutting. <P>SOLUTION: By preparing a master substrate 1 to be worked composed of a brittle material such as ceramics and manufacturing the strip-shaped slave substrate 1a to be worked by performing the primary cutting of the master substrate 1 to be worked along a broken line Y being a cutting predetermining part and forming holes 3 along a cutting line K, the strip-shaped slave substrate 1a to be worked is cut by taking the recessed part 3a as the starting point and the chip-sized substrate 1b is manufactured. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a laser cleaving method for cleaving a substrate to be processed using a crack generated by irradiating a laser to a workpiece substrate made of a brittle material such as glass, ceramic, or a semiconductor material.

  As a method of cutting a workpiece substrate made of a brittle material such as ceramic, generally, cutting with a disk-shaped rotary blade or fusing with a laser is known.

  However, in these methods, since cutting is performed by cutting with a rotary blade or fusing with a laser, the substrate to be processed requires a part of material to be deleted by these processing as a cutting allowance. There was a problem that the material cost was high. In addition, since it takes time to completely remove the part to be cut, there is a problem that the processing cost is high, and mechanical cracks and non-uniform thermal stress cause cracks in parts other than the part to be cut. There was also a problem that chipping occurred.

  Therefore, in order to solve such a problem, a laser cleaving method for cleaving a substrate to be processed made of a brittle material using thermal stress caused by laser irradiation has been proposed. Such a laser cleaving method has the advantage that, compared with the above-described fusing by laser, for example, less energy is required for processing and less material is deleted, so that material costs and processing costs can be reduced. is there.

  Moreover, generally, when a ceramic substrate or the like is cleaved from a mother substrate into a chip size of a desired size, after a primary cleaving step of obtaining a strip-shaped workpiece substrate by cleaving the workpiece mother substrate at a portion to be cleaved, The strip-shaped workpiece substrate is cleaved in the short side direction to perform a secondary cleaving step of obtaining a chip-sized ceramic substrate.

  In such a laser cleaving method, a deviation of the starting position of the crack or a deviation of the stress at the end point occurs, so that the cleaving accuracy can be improved by forming a recess at the intersection of the planned cleaving part. Has been done.

  One such laser cleaving method is described in Patent Document 1. Hereinafter, the laser cleaving method of Patent Document 1 will be described with reference to FIG.

  First, as shown in FIG. 4A, a workpiece substrate 11 is prepared in which a hole 13 is formed at the intersection of a broken line X and a broken line Y, which is a part to be cleaved. The holes 13 are formed in advance when the processed mother board 11 is laminated without being pre-processed.

Next, as shown in FIG. 4 (B), the laser irradiation position of the laser irradiation apparatus 2 is moved along the broken line Y so that the cracks follow the laser irradiation and progress, and a strip-shaped workpiece. The substrate 11a is produced. Thereafter, the laser irradiation position of the laser irradiation device 2 is moved along the broken line X, and cracks are similarly developed to produce individual chip size ceramic substrates.
Japanese Patent Laid-Open No. 10-263865

  By the way, in patent document 1, the sheet | seat in which the hole was formed previously is laminated | stacked, and the raw | molding mother board | substrate which consists of brittle materials, such as a ceramic which has the hole 13, is manufactured. In other words, the raw substrate to be processed is fired in a state where there is a hole. In this case, as shown in FIG. 5, countless microcracks C are generated at the edge of the hole 13 due to ceramic shrinkage or the like during firing. When the mother substrate 11 having the holes 13 is irradiated with a laser, the microcracks C are used as starting points to cause cracks. Basically, the microcrack C along the direction in which the laser irradiation position LB is moved develops into a crack, and this crack progresses.

  Here, as shown in FIG. 4B, when the laser beam is scanned along the broken line Y when the mother substrate 11 is divided in the vertical direction after the hole 13 is formed, the vertical wave line Y in FIG. The microcrack C1 along is most advanced. At this time, although not as small as the microcrack C1 along the longitudinal wave line Y, microcracks in other directions also develop by laser irradiation.

  Thereafter, when cleaving along the broken line X, scanning the laser along the broken line X causes the microcracks C2 along the transverse wave line X to develop and cause cracks. When microcracks in directions other than C1 and C2 that have developed when cleaved along Y further develop, there arises a problem that cracks are generated starting from undesired portions. As a result, there has been a problem that a chip-sized substrate, which is the final shape, has a distorted shape, resulting in a defective product.

  The micro cracks that cause this are not limited to the case where the holes are formed in the raw state as in Patent Document 1, but the holes are formed in the mother substrate after firing with a laser or a mechanical processing jig. Even if it is always formed. Microcracks are also necessary for forming a starting point for cleaving a strip-shaped workpiece substrate into a chip-sized substrate.

  The present invention has been made in view of the above points, and when a strip-shaped workpiece substrate is cleaved into chip sizes, cracks from undesired portions having holes as starting points are provided. The present invention provides a laser cleaving method capable of preventing the occurrence.

  That is, the laser cleaving method according to claim 1 of the present invention includes a step of cleaving a workpiece base substrate made of a brittle material to form a strip-shaped workpiece substrate, and a long side of the workpiece substrate, Forming a recess serving as a starting point for cleaving the workpiece substrate, and locally heating the workpiece substrate by irradiating a laser near the recess, and the thermal stress of the workpiece substrate The method includes a step of generating a crack in the concave portion and a step of cleaving the strip-shaped workpiece substrate by causing the crack to propagate by laser irradiation.

  Further, in the laser cleaving method according to claim 2 of the present invention, after the step of forming the workpiece substrate, the outer shape of the workpiece mother substrate is maintained while the workpiece substrate is cleaved. A recess serving as a starting point for cleaving the workpiece substrate is formed.

  Furthermore, in the laser cleaving method according to claim 3 of the present invention, in the step of forming a recess serving as a starting point for cleaving the workpiece substrate, recesses are formed on both sides of two opposing long sides of the workpiece substrate. It is characterized by forming.

  Further, in the laser cleaving method according to claim 4 of the present invention, in the cleaving process of the workpiece substrate, after scanning the entire width of the workpiece substrate by scanning the laser in the crack propagation direction. The laser is scanned in the direction opposite to the crack propagation direction.

  In the laser cleaving method of the present invention, a crevice serving as a cleaving starting point is formed after cleaving a workpiece substrate to a workpiece substrate. As a result, when the workpiece substrate is cleaved into the workpiece substrate, there are no recesses and no microcracks, so that microcracks in undesired directions do not develop. Therefore, when the workpiece substrate is cleaved into chip sizes, it is possible to prevent cracks from progressing in an undesired direction, and a substrate having a desired shape can be obtained.

  When the workpiece substrate is cleaved into the workpiece substrate, although there is a deviation of the starting point at the edge of the workpiece substrate, cracks progress along the movement of the laser irradiation position in the other portions. For this reason, when viewed from the whole processed mother board, since it is processed with high accuracy except for the starting portion, no major problem occurs.

  Further, in the laser cleaving method according to claim 2 of the present invention, after the step of forming the workpiece substrate, the workpiece is processed while maintaining the outer shape of the workpiece mother substrate in a state in which the workpiece substrate is cleaved. A recess serving as a starting point for cleaving the substrate is formed. Thereby, since a recessed part can be simultaneously formed in the to-be-processed substrate on the both sides of a recessed part, it can process efficiently. In addition, since the recess is processed while maintaining the outer shape of the workpiece mother substrate, the position of the recess is clear and the recess can be formed with high accuracy.

  Further, in the laser cleaving method according to claim 3 of the present invention, in the step of forming a recess serving as a starting point for cleaving the workpiece substrate, recesses are formed on both sides of two opposing long sides of the workpiece substrate. Forming. Thereby, at the time of the secondary cleaving process which cleaves a to-be-processed substrate, since the crack which started from the microcrack of the recessed part of both sides is easy to be connected and it is easy to cleave, processing accuracy can be improved.

  Further, in the laser cleaving method according to claim 4 of the present invention, in the cleaving process of the workpiece substrate, after scanning the entire width of the workpiece substrate by scanning the laser in the crack propagation direction. The laser is scanned in the direction opposite to the crack propagation direction. As a result, in the secondary cleaving step of cleaving the workpiece substrate, the crack near the end point side where the laser was first scanned propagates when the laser is scanned in the reverse direction, so that the chip size substrate is completely formed. Can be cleaved.

  Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic explanatory view showing each step of cleaving the workpiece substrate 1 into chip-sized substrates 1b.

  First, as shown in FIG. 1A, a workpiece mother substrate 1 made of a brittle material such as ceramic is prepared, and the laser of the laser irradiation apparatus 2 is cut along a broken line Y that is a portion to be cut of the workpiece mother substrate 1. Move the irradiation position. A strip-shaped workpiece substrate 1a is produced by causing cracks to propagate by this laser scanning and primarily cleaving the workpiece substrate 1. Examples of the brittle material of the mother substrate to be processed include single crystals such as glass, alumina ceramic, silicon, and lithium tantalate, low-melting glass fired ceramic, quartz, and semiconductor materials.

  The primary cleaving step may be cleaved using, for example, a mechanical cutting tool other than laser cleaving. However, when laser cleaving is used in the primary cleaving step, the subsequent laser drilling is performed using laser cutting. By changing the output to a strong condition so as to open a hole, it becomes possible to perform continuous processing with the same laser processing apparatus. Therefore, it is preferable to use laser cleaving in the primary cleaving step.

  Next, as shown in FIG. 1 (B), the cutting line K cut by the broken line Y is maintained while maintaining the outer shape of the processed mother board 1 obtained by laser cutting the plurality of strip-shaped workpiece substrates 1a. Correspondingly, the holes 3 are formed at predetermined intervals. The interval between the holes 3 corresponds to the chip size of the final chip-shaped ceramic substrate. By forming the hole 3 on the breaking line K, the hole 3 is formed over both of the two workpiece substrates 1a divided by the breaking line K. Therefore, the hole 3 can be efficiently formed with high positional accuracy. The laser beam is appropriately selected depending on the material of the substrate to be processed, but a CO2 laser, a YAG laser, or the like can be used. In addition, when drilling using the same laser processing equipment in succession to the primary cleaving process, in the primary cleaving process by laser, the spot diameter is enlarged and the target substrate is irradiated with laser, and the laser drilling is performed. In this process, the focus is adjusted.

  Further, as shown in FIG. 1 (C), when the strip-shaped workpiece substrate 1a is viewed individually, the portion that was the hole 3 in the state where the outer shape of the workpiece substrate 1 is maintained is divided. A semicircular recess 3a that is recessed in the plane direction is formed on the long side of the workpiece substrate 1a.

  The laser irradiation position of the laser irradiation apparatus 2 is moved in the direction of the white arrow along the broken line X, which is the planned cutting portion of the strip-shaped workpiece substrate 1a having the semicircular recess 3a. By this laser scanning, a crack starting from the semicircular recess 3a is developed to cleave the workpiece substrate 1a, thereby producing a chip-sized ceramic substrate 1b.

  As described above, since the concave portion that becomes the starting point is formed after cleaving to the strip-shaped workpiece substrate, when cleaving to the strip-shaped workpiece substrate, there is almost no starting microcrack, Cracks that cause undesired progress are less likely to occur. Therefore, as a result of cleaving the strip-shaped workpiece substrate, it is possible to prevent the obtained chip-sized substrate from having a distorted shape.

  Moreover, since the recessed part used as the starting point of a crack is formed in both the long sides of a strip-shaped workpiece substrate, a crack generate | occur | produces from both and a processing precision can be improved.

  In addition, the problem caused by such a shift of the starting point of the crack is that in the secondary cleaving process of cleaving the strip-shaped workpiece substrate to the chip size substrate, and the workpiece substrate from the workpiece mother substrate. In the primary cleaving process that cleaves, there is not much problem. This is because, in the case of the mother substrate 1 to be processed, the cleaving distance is long, so that even if the starting point is slightly deviated, it gradually approaches the desired cleaving portion. That is, as shown in FIG. 2, when laser processing is performed on the workpiece substrate 1, laser irradiation is performed even if the position of the starting point S is deviated from the broken line Y that is a portion to be cut at the end of the workpiece substrate 1. By scanning the region LB along the broken line Y, a cutting line K that follows the scanning trajectory and approximates the desired planned cutting part Y is obtained.

  Next, a laser cleaving method according to a second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a schematic plan view of a strip-shaped workpiece substrate 1a processed by the laser cleaving method according to the second embodiment of the present invention.

  The second embodiment differs from the above-described first embodiment in that the laser scanning is reciprocated. That is, as shown in FIG. 3, on the strip-shaped workpiece substrate 1a, the laser irradiation region LB is moved in the direction of the black arrow from the concave portion 3a on one long side toward the concave portion 3a on the other long side. . After reaching the other long side recess 3a, the laser irradiation region LB is turned to the one long side recess 3a in the direction of the white arrow. Thus, by reciprocating the scanning of the laser, the strip-shaped workpiece substrate 1a is cleaved in the short side direction to obtain the chip-sized substrate 1b.

  In this embodiment, since the laser scanning is reciprocated, even if the crack is not completely formed in the vicinity of the concave portion 3a at the end by the first laser scanning, the crack progresses by the second laser scanning and is reliably cleaved. It can be performed.

Schematic explanatory drawing which shows from the primary cleaving process of the to-be-processed mother board which concerns on this invention to the secondary cleaving process of a to-be-processed substrate. Schematic explanatory drawing which shows the relationship between a starting point shift | offset | difference and the locus | trajectory of a laser irradiation position. The top view of the to-be-processed substrate processed with the laser cleaving apparatus which concerns on 2nd Embodiment of this invention. Schematic explanatory drawing which shows from the primary cleaving process of the to-be-processed mother board | substrate at the time of using the conventional laser cleaving method to the secondary cleaving process of a to-be-processed substrate. Schematic explanatory drawing which shows the relationship between the micro crack around the hole used as the starting point, and the laser irradiation position at the time of primary cleaving.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,11 Substrate to be processed 1a, 11a Substrate to be processed 1b Chip-sized substrate 2 Laser irradiation device 3, 13 Hole 3a Recess X, Y Planned part C1, C2 Microcrack K Split line S Starting point LB Laser irradiation region

Claims (4)

A step of cleaving a processed mother substrate made of a brittle material to form a strip-shaped processed child substrate;
Forming a recess serving as a starting point for cleaving the workpiece substrate on the long side of the workpiece substrate;
A step of locally heating the workpiece substrate by irradiating a laser in the vicinity of the recess, and causing a crack in the recess of the workpiece substrate by the thermal stress;
Cleaving the strip-shaped workpiece substrate by advancing the crack by laser irradiation;
A laser cleaving method comprising:   After the step of forming the workpiece substrate, forming a recess serving as a starting point for cleaving the workpiece substrate while maintaining the outer shape of the workpiece mother substrate in a state in which the workpiece substrate is cleaved. 2. The laser cleaving method according to claim 1, wherein:   3. The laser according to claim 1, wherein, in the step of forming a recess serving as a starting point for cleaving the workpiece substrate, the recess is formed on both sides of two opposing long sides of the workpiece substrate. Cleaving method.   In the cleaving step of the workpiece substrate, after scanning the entire width of the workpiece substrate by scanning the laser in the crack propagation direction, the laser is scanned in the direction opposite to the crack propagation direction. The laser cleaving method according to any one of claims 1 to 3.