JP2016040809A - Processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable prevention of adhesion of debris to a substrate and a resin layer formed by a silicone resin or an epoxy resin.SOLUTION: A processing method of a plate-like work (W) including a resin layer (95) on a top face of a substrate (94), which is formed by a silicone resin or an epoxy resin and partitioned by division scheduled lines (96) comprises the steps of: coating the top face of the resin layer with a protective member (L) obtained by mixture of a water soluble resin and a silane compound to form a protection film (98) on a whole area of the top face of the resin layer by the protective member; subsequently irradiating laser beams from a top face of the protective film to cut the resin layer by the laser beams transmitting the protective film; and subsequently irradiating laser beams on a part of the substrate where the resin layer is cut to cut the substrate to create chips (C).SELECTED DRAWING: Figure 2

Description

  The present invention relates to a processing method for generating chips by irradiating a plate workpiece with a laser beam.

  Conventionally, a wafer in which optical devices such as light emitting diodes and laser diodes are formed in a plurality of regions partitioned by a plurality of streets formed in a lattice shape is known as a plate-like workpiece. In this wafer, chips that become individual optical devices are manufactured by cutting along the streets. As such a wafer cutting method, a method of performing ablation processing by irradiating a laser beam along a street has been proposed (see Patent Documents 1 and 2).

  However, when a wafer is irradiated with a laser beam, thermal energy is concentrated in the region irradiated with the laser beam, and debris (dissolved material) is generated, and this debris adheres to the surface of the chip and degrades the quality of the chip. There is a problem. Therefore, Patent Documents 1 and 2 propose a method of covering the processed surface side of the wafer with a protective film formed of a protective member in order to avoid adhesion of debris.

  On the other hand, as a plate-like work serving as a wafer for an optical device, one having a resin layer formed of a silicone resin or an epoxy resin on the upper surface of a substrate is known. The resin layer protects the surface of the light emitting part. In a high-power substrate, the resin layer is formed of a silicone resin in order to prevent discoloration of the resin layer due to heat generation.

JP 2004-188475 A JP 2008-78581 A

  In Patent Document 1, a protective member for covering a processed surface of a wafer is made of a water-soluble resin whose main component is polyvinyl alcohol or the like. When this protective member is applied to the surface of a resin layer formed of a silicone resin and dried, the surface of the silicone resin has water repellency, so there is a region where the protective member is water repellent and no protective film is formed. There is a problem that debris adheres to the region. Further, since the adhesion of the protective film to the surface of the silicone resin is weakened, there is a problem that the protective film is peeled off by laser processing, and laser burning or debris adhesion occurs on the silicone resin or the wafer.

  Moreover, in patent document 2, the liquid protection member which has water-soluble silicone oil as a main body is coat | covered on the process surface of a wafer, and the laser beam is irradiated in the state in which the protection member has fluidity | liquidity. In this laser beam irradiation, it is desirable that the assist gas is jetted to the processed surface side of the wafer when the silicone resin is ablated. When such a liquid protective member is applied to the surface of a resin layer formed of a silicone resin and irradiated with a laser beam, and assist gas is injected at the same time, the protective member is scattered by the force of the assist gas. For this reason, the surface of the silicone resin cannot be protected, and this also causes a problem that laser burning or debris adhesion occurs on the silicone resin or the wafer.

  In addition, about the problem mentioned above, when the resin layer is formed of an epoxy resin, the same problem occurs.

  This invention is made | formed in view of this point, and can adhere a protective film to the surface of the resin layer formed with the silicone resin or the epoxy resin, and prevents that a debris adheres to a resin layer or a board | substrate. It aims at providing the processing method which can be performed.

  A processing method according to the present invention includes a resin layer formed of a silicone resin or an epoxy resin on an upper surface of a substrate, and irradiates a laser beam from the resin layer side of a plate-like workpiece defined by the division schedule line, Is a processing method of generating a chip by cutting the resin layer and the substrate along with a protective member in which a water-soluble resin and a silane compound or colloidal silica are mixed on the upper surface of the resin layer. A protective film forming step of forming a protective film on the entire upper surface of the substrate with a protective member, a substrate on which the protective film is formed is held by a chuck table, a laser beam is irradiated from the upper surface of the protective film, and the laser passes through the protective film A resin layer cutting step of cutting the resin layer with a light beam, and a chip generation step of generating a chip by irradiating a laser beam to a portion of the substrate where the resin layer is cut to generate a chip. And butterflies.

  According to this configuration, since the protective member in which the water-soluble resin and the silane compound are mixed is used, the silane compound functions as an adhesion assistant, and the adhesion of the protective film to the resin layer can be improved. This prevents the protective member from being water-repellent on the upper surface of the resin layer, resulting in non-protective film formation regions or the formation of protective film peeling regions due to laser processing, and debris adhering to those regions. Or laser burn can be prevented. In addition, the protective film can be formed on the entire top surface of the resin layer in a dry state without the protective member having fluidity at the time of laser beam irradiation. Therefore, laser processing using assist gas can be performed, and this can also prevent debris from adhering to the resin layer and the substrate.

  In the processing method of the present invention, the protective member may be a mixture of a water-soluble resin, a silane compound, and an organic solvent. In this configuration, since the organic solvent is mixed, heat dissipation is improved and laser burn can be prevented at the time of laser processing for the plate-like workpiece.

  According to the present invention, since the protective member in which the water-soluble resin and the silane compound are mixed is used, the protective film can be adhered to the surface of the resin layer formed of a silicone resin or an epoxy resin. It is possible to prevent debris from adhering to the substrate.

FIG. 1A is a perspective view of a plate-like workpiece according to the present embodiment, and FIG. 1B is a perspective view of a laser processing apparatus according to the present embodiment. 2A and 2B are explanatory diagrams of the protective film forming step according to the present embodiment. It is explanatory drawing of the resin layer cutting process which concerns on this Embodiment. It is explanatory drawing of the chip | tip production | generation process which concerns on this Embodiment.

  Hereinafter, a processing method according to the present invention will be described with reference to the accompanying drawings. First, with reference to FIG. 1A, the plate-shaped workpiece processed by the processing method according to the present embodiment will be described. FIG. 1A is a schematic perspective view of a plate-like workpiece.

  As shown in FIG. 1A, the plate-like workpiece W includes a substrate 94 formed of a rectangular alumina ceramic plate. The base material 94 is divided into a plurality of regions by grid-like division planned lines 96. An optical device is formed in each area divided by the planned division lines 96. A silicone resin having translucency is applied to the surface of the base 94 to form a resin layer 95 that protects the optical device.

  The resin layer 95 is formed with a convex (dome-shaped) hemispherical surface 93 corresponding to each optical device. The hemispherical surface 93 functions as a lens, and improves the luminance by diffusing light emitted from the light emitting portion of the optical device. The plate-like workpiece W is not limited to a workpiece for an optical device, but may be a workpiece for a semiconductor or various package substrates. Therefore, the base 94 may be a glass or sapphire inorganic material substrate, or a semiconductor substrate such as silicon or gallium arsenide. The resin layer 95 of the plate-like workpiece W may protect the device with an epoxy resin instead of the silicone resin.

  Subsequently, a laser processing apparatus to which the processing method according to the present invention is applied will be described with reference to FIG. 1B. FIG. 1B is a perspective view of the laser processing apparatus according to the present embodiment. The laser processing apparatus according to the present invention is not limited to the laser processing apparatus shown in FIG. 1B. The laser processing apparatus may be configured in any way as long as the processing method according to the present invention is applied.

  As shown in FIG. 1B, the laser processing apparatus 1 irradiates a rectangular plate-like plate-like workpiece W on the chuck table 20 with a laser beam, and cuts the plate-like workpiece W into individual chips C (see FIG. 4). Is configured to do.

  The chuck table 20 is configured such that a holding block 22 capable of individually holding each chip C after the division of the plate-like workpiece W is disposed on a base member 21 serving as a base. A number of holes formed in the upper surface (holding surface) of the holding block 22 are communicated with a suction source (not shown) through a suction path formed in the base member 21. When the upper surface of the holding block 22 becomes negative pressure by the suction force from the suction source, the plate-like workpiece W is sucked and held on the upper surface of the holding block 22.

  A chuck table moving mechanism 30 for moving the chuck table 20 in the X-axis direction and the Y-axis direction is provided on the base 10 of the laser processing apparatus 1. The chuck table moving mechanism 30 includes a pair of guide rails 31 arranged on the base 10 and parallel to the X-axis direction, and a motor-driven X-axis table 32 slidably installed on the pair of guide rails 31. doing. The chuck table moving mechanism 30 includes a pair of guide rails 33 arranged on the X-axis table 32 and parallel to the Y-axis direction, and a motor-driven Y-axis table 34 slidably installed on the pair of guide rails 33. And have.

  Nut portions (not shown) are formed on the back sides of the X-axis table 32 and the Y-axis table 34, and ball screws 35 and 36 are screwed into these nut portions. Then, the drive motors 37 and 38 connected to one end portions of the ball screws 35 and 36 are rotationally driven, so that the chuck table 20 is moved along the guide rails 31 and 33 in the X-axis direction and the Y-axis direction. On the Y-axis table 34, the chuck table 20 is rotatably provided via a θ table 39.

  In addition, a standing wall portion 11 is erected on the rear side of the base 10 behind the chuck table moving mechanism 30, and an arm 12 projects from the standing wall portion 11 toward the upper side of the chuck table 20. A laser irradiation means 50 for irradiating a laser beam along a planned division line 96 of the plate-like workpiece W is provided at the tip of the arm 12. Connected to the laser irradiation means 50 are a gas supply unit 52 for injecting an assist gas to an irradiation region of the laser beam and an output variable unit 53 for changing the laser output of the laser beam (see FIGS. 3 and 4). .

  The processing of the plate-like workpiece W by the laser irradiation means 50 is performed by ablation processing using a laser beam having a wavelength that has an absorptivity for the plate-like workpiece W. Ablation means that when the irradiation intensity of the laser beam exceeds a predetermined processing threshold, it is converted into electronic, thermal, photochemical and mechanical energy on the solid surface, and as a result, neutral atoms, molecules, positive and negative A phenomenon in which ions, radicals, clusters, electrons, and light are explosively emitted and the solid surface is etched. The assist gas according to the present embodiment is compressed air, and is appropriately changed to a gas such as oxygen or nitrogen according to the material of the plate-like workpiece W or the like.

  In the laser processing apparatus 1 configured as described above, the laser beam is irradiated from the laser irradiation means 50 onto the plate-like workpiece W, and the assist gas is injected into the irradiation region of the laser beam. Then, by moving the chuck table 20 in the state of being irradiated with the laser beam, the plate-like workpiece W is ablated along the scheduled division line 96. In addition, in this Embodiment, although it was set as the structure which processes the plate-shaped workpiece | work W by ablation processing, it is not limited to this structure. Any processing may be used as long as the processing can be performed while the plate-like workpiece W is melted by the laser beam.

  In order to divide the plate-like workpiece W according to the present embodiment, the laser output is changed between processing of the resin layer 95 made of silicone resin and processing of the substrate 94 made of alumina ceramic.

  A protective film forming means 40 is provided on the side of the base 10 and in front of the standing wall portion 11. The protective film forming means 40 has a protective film forming table (holding part) 41 for holding the plate-like workpiece W, a substantially rectangular opening 42 on the upper surface, and the protective film forming table 41 in the opening 42. And a housing 43 that can be accommodated. In the vicinity of the opening 42 on the upper surface of the housing 43, a supply nozzle 44 that supplies a liquid protective member to the plate-like workpiece W and a shutter mechanism 45 that can open and close the opening 42 are provided. A cleaning nozzle (not shown) for supplying cleaning water to the plate-like workpiece W is provided inside the housing 43.

  The protective film forming table 41 has the same structure as that of the chuck table 20 and is configured to be able to suck and hold the plate-like workpiece W. The protective film forming table 41 is configured to be rotatable around the Z axis via a rotating means 46. The protective film forming table 41 is configured to be movable up and down between the opening 42 of the housing 43 and the inside of the housing 43. The supply nozzle 44 is connected to a protection member tank 47 that stores the protection member, and the protection member is supplied from the protection member tank 47 to the supply nozzle 44.

  Conveying the plate-like workpiece W between the laser processing area in the base 10 and the protective film forming / removing area in the protective film forming means 40 on the front surface of the standing wall 11 above the protective film forming means 40 Means 80 are provided.

  The transport means 80 has a pair of upper and lower guide rails 81, 81 extending in the Y-axis direction on the front surface of the standing wall portion 11, and a transport arm 82 slidably engaged with the pair of guide rails 81, 81. doing. A ball screw 83 extending in the Y-axis direction is screwed to the transfer arm 82. A drive motor 84 is connected to one end of the ball screw 83, and the ball screw 83 is rotationally driven by the drive motor 84 to move the transfer arm 82 in the Y-axis direction. On the lower end side of the transfer arm 82, a holding portion 85 is provided that holds the outer periphery of the plate-like workpiece W therebetween. The transport means 80 configured in this manner picks up the plate-like workpiece W from the protective film forming table 41 of the protective film forming means 40 after the formation of the protective film on the plate-like workpiece W, and The plate-like workpiece W is placed on the surface. Then, after the laser processing of the plate-like workpiece W, the conveying unit 80 picks up the plate-like workpiece W from the chuck table 20 and places it on the protective film forming table 41 of the protective film forming unit 40.

  Here, the configuration of the protection member will be described below. The protective member is configured by mixing a water-soluble resin and a silane compound or colloidal silica, and is preferably configured by further mixing an organic solvent. The silane compound is composed of a single silane coupling agent or a mixture of a silane coupling agent and colloidal silica.

The silane coupling agent is configured as shown by the following chemical formula [Chemical Formula 1]. In this chemical formula, X: methyl, ethyl, ketone, etc., Y: none, epoxy, methacryl, vinyl, mercapto, etc.

Colloidal silica is configured as shown by the chemical formula [Chemical Formula 2] below. In this chemical formula, Y: none, epoxy, methacryl, vinyl, mercapto and the like. Colloidal silica is configured to include silica having a particle size of 5 to 200 nm. The silica particles are preferably finer (5 nm) because the laser light is scattered by the silica.

  The water-soluble resin is a nonionic water-soluble resin such as polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), polyacrylamide, or polyethylene glycol. Examples of the organic solvent include solvents containing propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethylene glycol, and lactic acid. When the protective member contains the organic solvent, the heat dissipation is improved when the plate-shaped workpiece is irradiated with the laser beam, and the protective film described later can be prevented from being burned. In the present embodiment, a solvent in which a water-soluble resin, an organic solvent, and water are mixed is used. As an example, a solvent in which 20 wt% of polyvinyl alcohol (PVA (water-soluble resin)) is prepared with respect to the mass of a mixed solution of propylene glycol monomethyl ether (organic solvent): 18 wt% and water: 82 wt%. Can be mentioned. The solvent may be PVA: 1 to 15 wt%, organic solvent: 1 to 20 wt%, water: 60 to 90 wt%, and the total may be 100 wt%.

  Next, a processing method using a laser processing apparatus will be described with reference to FIG. 2 to 4 are explanatory diagrams of the processing method according to the present embodiment. 2 shows a protective film forming step, FIG. 3 shows a resin layer cutting step, and FIG. 4 shows a chip generation step. Note that the various operations shown in FIGS. 2 to 4 are merely examples, and can be changed as appropriate.

  As shown in FIG. 2A, a protective layer forming step is first performed. In the protective layer forming step, the lower surface side of the plate-like workpiece W is sucked and held by the protective film forming table 41 with the resin layer 95 of the plate-like workpiece W directed upward. Next, the protective film forming table 41 is raised to a position facing the supply nozzle 44, and the liquid protective member L is applied from the supply nozzle 44 to the processing surface of the plate-like workpiece W. Then, the protective film forming table 41 is lowered into the housing 43 (see FIG. 1B) and rotated at a high speed to spread the protective member L over the entire upper surface of the resin layer 95 in the plate-like workpiece W as shown in FIG. 2B. Thus, the protective film 98 is formed. The protective film 98 is dried and solidified after a predetermined time.

  After the protective layer forming step is performed, the plate-like workpiece W on which the protective film 98 is formed is conveyed onto the chuck table 20 by the conveying means 80 (see FIG. 1B). Thereafter, as shown in FIG. 3, a resin layer cutting step is performed. In this step, the lower surface side of the substrate 94 is sucked and held by the holding block 22 of the chuck table 20 with the resin layer 95 of the plate-like workpiece W directed upward. The chuck table 20 is moved below the laser irradiation means 50, and the laser irradiation means 50 is positioned on the planned division line 96 of the plate-like workpiece W. Then, the laser beam emitted from the laser irradiation means 50 passes through the protective film 98 and is irradiated onto the resin layer 95 of the plate-like workpiece W, and assist gas is blown onto the irradiation region of the laser beam.

At this time, the laser irradiation means 50 is moved relative to the plate-like workpiece W while the condensing point of the laser beam is adjusted, so that the resin layer 95 of the plate-like workpiece W is cut along the division line 96. A dividing groove 99 is formed. The dividing groove 99 is formed over the protective film 98 by the thermal energy of laser processing. The processing conditions in the resin layer cutting step are processing conditions corresponding to the silicone resin, and are set as follows, for example.
Laser Type: CO ₂ laser wavelength: 9.4Um
Repetition frequency: CW
Output: 50 [W]
Processing feed rate: 600 [mm / sec]
Gas (assist gas): Air 200 [L / min]
By performing laser processing under such processing conditions, the resin layer 95 made of silicone resin is appropriately removed and cut. The laser beam may be a pulse wave, and is set as follows, for example.
Laser type: CO ₂ laser Output: 20 [W]
Repetition frequency: 100 [kHz]
Processing feed rate: 200 [mm / sec]
Gas (assist gas): Air 200 [L / min]

  After the resin layer cutting step is performed, a chip generation step is performed as shown in FIG. In this step, the processing conditions corresponding to the resin layer 95 made of silicone resin are changed to the processing conditions corresponding to the substrate 94 made of alumina ceramic. Further, the laser irradiation means 50 is positioned on the division line 96 (dividing groove 99) of the plate-like workpiece W. Then, in a state where the laser output is increased by the output variable unit 53, the assist gas is blown together with the laser beam from the laser irradiation means 50 to the divided groove 99 which is a portion where the resin layer 95 of the plate-like workpiece W is cut. It is done.

  Thereby, the substrate 94 is cut by the laser beam while the debris generated by the dissolution of the plate-like workpiece W is blown away by the assist gas. And when the base material 94 penetrates and continues to the dividing groove 99 of the resin layer 95, the plate-like workpiece W is completely cut and individual chips C are generated.

The processing conditions in the chip generation process are processing conditions corresponding to alumina ceramic, and are set as follows, for example. In this case, the processing conditions corresponding to the alumina ceramic are such that the laser output is increased and the feed rate is decreased with respect to the processing conditions corresponding to the silicone resin.
Laser type: CO ₂ laser Output: 50 [W]
Repetition frequency: 100 [kHz]
Feeding speed: 40 [mm / s]
Gas (assist gas): Air 200 [L / min]
In the cutting process, a fiber laser may be used instead of the CO ₂ laser.

  After the chip generation process is performed, the plate-like workpiece W is transferred onto the protective film forming table 41 by the transfer means 80 (see FIG. 1B). Thereafter, the cleaning water is sprayed from the cleaning nozzle while the plate-like workpiece W is rotated at a high speed, so that the protective film 98 is dissolved by the cleaning water and removed together with the debris adhering to the protective film 98. Washed.

  As described above, according to the processing method according to the present embodiment, since the protective film 98 is formed by the protective member L mixed with the silane compound, the protective film 98 and the resin layer 95 are adhered to each other by the action of the silane compound. Can increase the sex. Thereby, it is possible to prevent the protective film 98 from being peeled off by laser processing or the injection of assist gas, and it is possible to prevent the resin layer 95 and the substrate 94 from being burned by laser and debris adhesion.

  In addition, when the protective member L includes the silane compound, it is possible to prevent the protective member L from being repellent on the upper surface of the resin layer 95 made of a silicone resin and a region where the protective film 98 is not formed. Therefore, laser burn of the resin layer 95 and the substrate 94 and adhesion of debris due to the non-formation region of the protective film 98 can be avoided. In addition, the protective film 98 can be uniformly formed on the entire upper surface of the resin layer 95 in a state where the protective member L is dry, and laser processing using assist gas can be performed.

  In the examples of the present invention, 20 wt% polyvinyl alcohol (PVA (water-soluble resin)) was prepared with respect to the mass of a solution mixed with a composition of propylene glycol monomethyl ether (organic solvent): 18 wt% and water: 82 wt%. A protective member was prepared by adding 1 g of trimethoxyphenylsilane (silane coupling agent) to 20 g of the solution. 50 ml of this protective member was applied to the upper surface of the resin layer of a plate-like workpiece having a planar size of 60 mm × 60 mm, and the plate-like workpiece was rotated at 2000 rpm for 60 seconds to form a protective film. The dried protective film had a thickness of 20 to 2000 nm and was formed on the entire upper surface of the resin layer in the plate-like workpiece.

  In addition, this invention is not limited to the said embodiment, It can change and implement variously. In the above-described embodiment, the size, shape, direction, and the like illustrated in the accompanying drawings are not limited to this, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  Further, in the above-described embodiment, the protective film forming process, the resin layer cutting process, and the chip generating process are performed by the single laser processing apparatus 1, but the present invention is not limited to this configuration, and each process is separately performed. It may be implemented in the apparatus.

  As described above, the present invention has an effect of preventing laser burn by laser processing and adhesion of debris. In particular, each wafer for an optical device having a resin protective layer such as silicone resin or epoxy resin is individually provided. It is useful for the processing method of dividing into chips.

DESCRIPTION OF SYMBOLS 1 Laser processing apparatus 20 Chuck table 94 Substrate 95 Resin layer 96 Divided line 98 Protective film C Chip L Protective member W Plate workpiece

Claims (2)

A resin layer formed of a silicone resin or an epoxy resin is provided on the upper surface of the substrate, and a laser beam is irradiated from the resin layer side of the plate-like workpiece defined by the division line, and the resin layer and the resin layer along the division line A processing method for generating a chip by cutting the substrate,
A protective film forming step in which a protective member in which a water-soluble resin and a silane compound or colloidal silica are mixed is applied to the upper surface of the resin layer, and a protective film is formed on the entire upper surface of the resin layer with the protective member;
A resin layer cutting step of holding the substrate on which the protective film is formed with a chuck table, irradiating a laser beam from the upper surface of the protective film, and cutting the resin layer with the laser beam passing through the protective film; ,
A chip generating step of generating a chip by irradiating a laser beam to a portion of the substrate where the resin layer has been cut;
A processing method comprising:   The processing method according to claim 1, wherein the protective member is a mixture of the water-soluble resin, the silane compound, and an organic solvent.

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