JP6004675B2 - Laser processing equipment - Google Patents

Description

  The present invention relates to a laser processing apparatus that performs ablation processing by irradiating a surface of a workpiece such as a wafer with a laser beam.

  The laser beam is applied to the planned division line of semiconductor wafers with devices such as IC (Integrated Circuit) and LSI (Large Scale Integration) and sapphire wafers with devices such as LED (Light Emitting Diode) elements. Irradiation and formation of grooves on the surface divide into individual devices, and electronic devices such as mobile phones, PCs (Personal Computers), and LED lights are manufactured.

  In this processing step, it is known that when a semiconductor wafer or sapphire wafer is irradiated with a laser beam, fine dust called debris is generated and scattered and deposited on the surface of the device, thereby degrading the quality of the device. As a countermeasure, a protective film is applied in advance, laser processing is performed, and the debris adhering to the protective film together with the protective film is cleaned and removed, or air along the optical axis of the objective lens is removed. There has been proposed a laser processing apparatus that includes a jet outlet that ejects and sucks debris from around the jet outlet to prevent the debris from accumulating on the surface of the device (for example, Patent Document 1, Patent Document 2, and Patent Document). 3).

JP 2007-69249 A JP 2011-189400 A JP 2006-032419 A

  However, in actual processing, it is necessary to remove the deposited debris so that it does not fall on the wafer again because it adheres to the mechanism that sucks liquid or vaporized debris generated from the protective film itself or the wafer itself. As a result, it is necessary to perform maintenance, or the air ejected along the optical axis does not perform its function sufficiently, and debris and vaporized debris adhere to optical parts such as a condenser lens.

  The present invention has been made in view of the above, and provides a laser processing apparatus capable of suppressing debris generated during laser processing from adhering to an optical component such as a collector without frequent maintenance. The purpose is to do.

In order to solve the above-described problems and achieve the object, a laser processing apparatus of the present invention includes a holding means for holding a wafer, and a laser beam irradiated to the surface of the wafer held by the holding means to perform ablation processing. Processing means having a condenser for forming a processing groove; and protection means for protecting the condenser from debris generated near the processing point by the laser beam disposed below the condenser and passing through the inside. A debris discharge means that sucks and discharges the debris below the protection means, and the debris discharge means surrounds the periphery of the debris scattering range generated near the processing point. parallel to the partition wall, and an opening in the vicinity of the lower opening of and the protection means on the inside of the partition wall, than said lower opening being disposed below, from the direction in which the processed groove is formed and the surface of the wafer Has a spout for jetting the gas, covering the said lower opening in gas blown from該噴outlet, the air curtain blowing ejection mechanism for blocking the debris from entering the said protection means, open and the partition wall Generated near the processing point while suctioning the gas downstream of the gas ejected by the air curtain blow ejection mechanism by connecting the suction port facing the ejection port and the suction source across the lower opening And a suction path for sucking the debris to be sucked.

  In the laser processing apparatus, it is preferable that the flow velocity of the gas ejected from the ejection port of the air curtain blow ejection mechanism is 600 m / s or more.

  In the laser processing apparatus of the present invention, gas is ejected from the ejection port of the air curtain blow ejection mechanism so as to block the lower opening of the protection means so as to protect the condenser from adhesion of debris. For this reason, it is possible to suppress debris from entering from the lower opening of the protection means, and to protect the condenser from the adhesion of debris and to suppress the occurrence of fogging of optical components due to the adhesion of debris in the atmosphere. Can do. Therefore, it is possible to suppress debris that has been vaporized especially during laser processing from adhering to optical components such as a condenser, and to prevent deterioration of the processing result due to a decrease in the amount of laser light reaching the processing point. Can do.

  In addition, since the debris discharge means has a suction port and a suction path, not only debris blown away by the gas ejected from the ejection port, but also debris generated near the processing point is sucked through the suction port from the side where it is scattered. And exhaust. In addition, since the lowermost opening portion formed by being surrounded by the inner surface of the partition wall of the debris discharge means has a minimum opening in a range covering the debris scattering range, the scattered debris is protected by the protective means and the debris discharge. Adhering to the means can be suppressed, and the protecting means and the debris discharging means are contaminated by the debris, and the adhering debris hangs down and falls on the surface of the wafer, thereby preventing the wafer from being contaminated.

  Moreover, since it can suppress that a debris adheres to a protection means or a debris discharge means, it is released also from the maintenance which removes the attached debris. Moreover, since the opening part of the lowermost surface formed surrounded by the inner surface of a partition wall is the minimum opening in the range which covers the scattering range of a debris, the attraction | suction force which attracts | sucks a debris is exhibited efficiently. Therefore, the laser processing apparatus of this invention can suppress that the debris which arises in the case of laser processing adheres to optical components, such as a collector, without performing frequent maintenance.

FIG. 1 is a diagram illustrating a configuration example of a laser processing apparatus according to an embodiment. FIG. 2 is a diagram schematically illustrating a configuration of a laser beam irradiation unit and a chuck table of the laser processing apparatus according to the embodiment. FIG. 3 is a perspective view illustrating a configuration of a protection unit and a debris discharge unit of the laser processing apparatus according to the embodiment. 4 is a cross-sectional view taken along line IV-IV in FIG. FIG. 5 is a cross-sectional view showing the main parts of the protection means and debris discharge means of the laser processing apparatus according to the embodiment. FIG. 6 is a perspective view of the debris discharge means of the laser processing apparatus according to the embodiment as seen from below. FIG. 7 is a perspective view of the main part of the debris discharge means of the laser processing apparatus according to the embodiment as seen from below. FIG. 8 is a flowchart of the laser processing method of the laser processing apparatus according to the embodiment.

  DESCRIPTION OF EMBODIMENTS Embodiments (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the contents described in the following embodiments. The constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the structures described below can be combined as appropriate. Various omissions, substitutions, or changes in the configuration can be made without departing from the scope of the present invention.

Embodiment
FIG. 1 is a diagram illustrating a configuration example of a laser processing apparatus according to an embodiment. FIG. 2 is a diagram schematically illustrating a configuration of a laser beam irradiation unit and a chuck table of the laser processing apparatus according to the embodiment. FIG. 3 is a perspective view illustrating a configuration of a protection unit and a debris discharge unit of the laser processing apparatus according to the embodiment. 4 is a cross-sectional view taken along line IV-IV in FIG. FIG. 5 is a cross-sectional view showing the main parts of the protection means and the debris discharge means of the laser processing apparatus according to the embodiment. FIG. 6 is a perspective view of the debris discharge means of the laser processing apparatus according to the embodiment as seen from below. FIG. 7 is a perspective view of the main part of the debris discharge means of the laser processing apparatus according to the embodiment as seen from below. FIG. 8 is a flowchart of the laser processing method of the laser processing apparatus according to the embodiment.

  The laser processing apparatus 1 according to the first embodiment temporarily covers a wafer W with a protective film P (shown in FIG. 4 and the like), and then holds the wafer W coated with the protective film P (corresponding to a holding unit). ) 10 and a laser beam irradiation means (corresponding to a processing means) 20 are moved relative to each other to ablate the wafer W to form a processing groove S (shown in FIG. 4) on the wafer W.

  As shown in FIG. 1, the laser processing apparatus 1 includes a chuck table 10, a laser beam irradiation unit 20, an imaging unit (not shown), a protection unit 30, a debris discharge unit 40, and a control unit 90. ing. The laser processing apparatus 1 further includes a cassette elevator 50 that accommodates the wafer W before and after laser processing, a temporary placement means 60 that temporarily places the wafer W before and after laser processing, and a wafer W before laser processing. And a protective film forming and cleaning means 70 that covers the protective film P and removes the protective film P from the wafer W after laser processing. Further, the laser processing apparatus 1 relatively moves the chuck table 10 and the laser beam irradiation means 20 in the Y-axis direction, and the X-axis movement means (not shown) that relatively moves the chuck table 10 and the laser beam irradiation means 20 in the X-axis direction. A Y-axis moving means (not shown) and a Z-axis moving means (not shown) for relatively moving the chuck table 10 and the laser beam irradiation means 20 in the Z-axis direction are configured.

  The cassette elevator 50 accommodates a plurality of wafers W attached to the annular frame F via the adhesive tape T. The cassette elevator 50 is provided in the apparatus main body 2 of the laser processing apparatus 1 so as to be movable up and down in the Z-axis direction.

  The temporary placing means 60 takes out one wafer W before laser processing from the cassette elevator 50 and accommodates the wafer W after laser processing in the cassette elevator 50. Temporary placement means 60 temporarily loads wafer W before laser processing from cassette elevator 50 and carries in / out means 61 for inserting wafer W after laser processing into cassette elevator 50, and wafer W before and after laser processing. And a pair of rails 62 to be placed.

  The protective film forming / cleaning means 70 is such that the wafer W before laser processing on the pair of rails 62 is transported by the first transport means 81 and the wafer W before laser processing is coated with the protective film P. is there. Further, the protective film forming / cleaning means 70 removes the protective film P from the laser-processed wafer W after the laser-processed wafer W is transferred by the second transfer means 82. The protective film forming / cleaning means 70 has a spinner table 71 on which the wafer W before and after laser processing is placed and held. The spinner table 71 is connected to a spinner table driving source housed in the apparatus main body 2.

  When the wafer W before laser processing is held on the spinner table 71, the protective film forming / cleaning means 70 rotates the wafer W by the rotational force generated by the spinner table driving source. The protective film forming / cleaning means 70 applies a liquid resin containing a water-soluble resin such as PVA, PEG or PEO to the surface WS of the wafer W from a coating nozzle (not shown). The protective film P is formed by curing. When the wafer W after laser processing is held on the spinner table 71, the protective film forming / cleaning means 70 rotates the wafer W by the rotational force generated by the spinner table driving source. Then, the protective film forming / cleaning means 70 removes the protective film P and cleans the surface WS of the wafer W by spraying a cleaning liquid onto the surface WS of the wafer W from a cleaning nozzle (not shown).

  The wafer W before laser processing is covered with a protective film P by a coating nozzle, and is placed on the chuck table 10 by the second conveying means 82. Further, the wafer W after laser processing is placed on the rail 62 of the temporary placement means 60 by the first transport means 81 after the protective film P is removed by the cleaning nozzle.

  In the chuck table 10, the wafer W on which the protective film P before laser processing on the spinner table 71 of the protective film forming / cleaning means 70 is formed is placed by the second transport means 82 and holds the wafer W. To do. The chuck table 10 has a disk shape in which a portion constituting the surface is made of porous ceramic or the like, and is connected to a vacuum suction source (not shown) through a vacuum suction path (not shown) to suck the wafer W placed on the surface. Hold by. The chuck table 10 can be attached to and detached from a table moving base (not shown) provided in the apparatus main body 2 of the cutting apparatus 1. The table moving base is movably provided in the X-axis direction by the X-axis moving means and is movably provided in the Y-axis direction by the Y-axis moving means, and a center axis ( (It is parallel to the Z-axis). Further, a clamp part 11 is provided around the chuck table 10, and the clamp part 11 is driven by an air actuator (not shown) so that the annular frame F around the wafer W is clamped.

  The laser beam irradiating means 20 irradiates the surface WS of the wafer W held on the chuck table 10 with a laser beam L (shown in FIG. 2 and the like), and forms a processed groove S by ablation processing. The laser beam irradiation means 20 is provided so as to be movable in the Z-axis direction with respect to the wafer W held on the chuck table 10 by the Z-axis movement means. As shown in FIG. 2, the laser beam irradiation means 20 includes an oscillator 21 that oscillates the laser beam L, and a condenser 22 that irradiates the surface WS of the wafer W with the laser beam L oscillated by the oscillator 21. Yes. In the oscillator 21, the frequency of the oscillating laser beam L is appropriately adjusted by the frequency adjusting unit 23 according to the type of wafer W, the processing form, and the like. As the oscillator 21, for example, a YAG laser oscillator or a YVO laser oscillator can be used. The condenser 22 includes a total reflection mirror 24 that changes the traveling direction of the laser beam L oscillated by the oscillator 21, a condenser lens 25 that collects the laser beam L, and the like.

  The imaging means images the surface WS of the wafer W held on the chuck table 10. The imaging unit is provided so as to be movable in the Z-axis direction integrally with the laser beam irradiation unit 20 by the Z-axis moving unit 50 with respect to the wafer W held on the chuck table 10. The imaging means includes a CCD camera (not shown). The CCD camera is an apparatus that captures an image of the wafer W held on the chuck table 10 and obtains an image. The imaging unit outputs information on the image obtained by the CCD camera to the control unit 90.

  As shown in FIG. 2, the protection means 30 is disposed below the light collector 22. The protection means 30 protects the concentrator 22 from debris generated near the processing point of the wafer W (a portion irradiated with the laser beam L) K by the laser beam L passing through the inside. Note that the debris generally includes fine dust made of the material constituting the wafer W and the protective film P, and vaporized debris that is vaporized particularly from the material constituting the protective film P. In the present embodiment, the protection means 30 particularly protects the condenser 22 from the vaporized debris, and suppresses the vaporized debris from adhering to the condenser 22 and the transparent member 33 described later by condensation and solidification. It is.

  As shown in FIGS. 3, 4, and 5, the protection means 30 includes a chamber 32 that is attached to the condenser 22 of the laser beam irradiation means 20 by a bracket (shown in FIG. 3), and a transparent that is attached to the chamber 32. A member 33 and a protective blow mechanism 34 for keeping the inside of the chamber 32 at a positive pressure are provided.

  The chamber 32 includes openings 32a and 32b through which the laser beam L passes vertically. The chamber 32 has a funnel-like conical diameter-reducing portion 32c that gradually decreases in diameter toward a lower opening (corresponding to the lower opening) 32b. That is, the space inside the reduced diameter portion 32c of the chamber 32 is formed in a funnel-shaped conical shape. The opening 32b below the chamber 32 has an area that allows the laser beam L to pass therethrough. In the present embodiment, the diameter of the lower opening 32b is 4 mm. In this embodiment, the chamber 32 is configured by laminating a plurality of flat laminated plates 35 and attaching a nozzle member 36 to the lowermost laminated plate 35 (hereinafter denoted by reference numeral 35a). In the present embodiment, the chamber 32 is improved in airtightness as much as possible by the plurality of laminated plates 35 and the nozzle member 36.

  The transparent member 33 is disposed in the opening 32 a above the chamber 32 and can transmit the laser beam L. The transparent member 33 has an area that allows the laser beam L to pass therethrough. The transparent member 33 is made of a material that can transmit the laser beam L, is formed in a flat plate shape, and closes the opening 32 a above the chamber 32.

  The protective blow mechanism 34 ejects a gas flowing from the collector 22 side to the processing point K side around the laser beam L passing through the chamber 32 to keep the inside of the chamber 32 at a positive pressure and debris from the lower opening 32b. It prevents the inflow of the atmosphere containing. As shown in FIGS. 3, 4, and 5, the protective blow mechanism 34 includes a plurality of protective jets 37, a supply path 38 (shown in FIG. 3), a gas supply source (not shown), and the like.

  The plurality of protective jets 37 are arranged uniformly (equally spaced in the circumferential direction) around the transparent member 33 without any deviation. The protective spout 37 is disposed around the lower side of the transparent member 33. One end of each of the plurality of protective jets 37 is opened in the inner surface of the chamber 32, and the other end is opened in a communication space 39 provided in the chamber 32. Further, the gas ejected from the protective ejection port 37 is ejected toward the laser beam L passing through the chamber 32 slightly downward from the horizontal so as not to hit the transparent member 33. In other words, the protective jet 37 has one end opened on the inner surface of the chamber 32 disposed below the transparent member 33, and extends slightly downward from the horizontal as it goes from the other end to the one end. In the present embodiment, eight protective jets 37 are provided.

  The supply path 38 is connected to a plurality of protective jets 37 through a communication space 39. The gas supply source is connected to the plurality of protective jets 37 via the supply path 38, and supplies pressurized gas to the plurality of protective jets 37.

  The debris discharge means 40 is disposed below the chamber 32 of the protection means 30 and sucks and discharges debris. As shown in FIGS. 3, 4, 5, 6, and 7, the debris discharge means 40 includes a partition wall 41 (shown in FIGS. 4 to 7) provided integrally with the chamber 32, and an air curtain blow jet. A mechanism 42 and a suction mechanism 43 are provided.

  The partition wall 41 surrounds the periphery of the debris scattering range (shown by dotted lines in FIGS. 4 and 5) generated at the processing point K. The partition wall 41 is provided on the lowermost laminated plate 35 a and the nozzle member 36 constituting the chamber 32. The partition wall 41 surrounds the periphery of the opening 32b below the chamber 32, as shown in FIGS. Note that the lowermost opening portion formed by being surrounded by the inner surface 41a of the partition wall 41 has a minimum opening within a range that covers the debris scattering range.

  The air curtain blow ejecting mechanism 42 has a surface WS of the wafer W from the direction in which the processing groove S is formed (in front of the arrow X1 in which the laser beam L relatively moves on the surface WS of the wafer W during laser processing). In parallel with the gas, the gas ejected from the ejection port 44 covers the opening 32b below the chamber 32 and blocks the entry of debris into the chamber 32 of the protection means 30. The air curtain blow ejection mechanism 42 includes an ejection port 44 provided in the nozzle member 36, a supply path 45, and a gas supply source (not shown) that supplies gas to the ejection port 44. The ejection port 44 opens on the inner surface (inner side) of the partition wall 41 provided in the nozzle member 36 and in the vicinity of the opening 32b below the chamber 32, and is disposed below the opening 32b below. The spout 44 extends in parallel with the surface WS of the wafer W. In the present embodiment, the ejection port 44 is configured such that the lower side of the groove formed on the surface of the nozzle body 36a of the nozzle member 36 is closed by the plate-like member 36b. Moreover, in this embodiment, the spout 44 is formed in a rectangular shape having a cross-sectional shape of a width of 1.8 mm and a height of 0.8 mm, and is disposed 1 mm below the lower opening 32b. It is disposed in the very vicinity of the opening 32b.

  The gas supply source is connected to the ejection port 44 via a supply path 45 provided in the chamber 32, and supplies pressurized gas to the ejection port 44. In the present embodiment, a supply source that supplies pressurized gas for driving an air cylinder of various factory equipment such as the laser processing apparatus 1 is used as the gas supply source. Further, in the air curtain blow ejection mechanism 42, the flow passage cross-sectional area of the supply passage 45 is formed to be much larger than the flow passage cross-sectional area of the ejection port 44, and the pressurized gas supplied from the gas supply source Loss of flow rate and flow velocity due to pipe resistance is suppressed. By doing so, the flow velocity of the gas ejected from the ejection port 44 of the air curtain blow ejection mechanism 42 is 600 m / s (about 1.7 times the speed of sound on the sea surface), and ejection from the ejection port 44. The gas to be discharged is ejected radially from the ejection port 44 toward the suction port 46 and closes the lower opening 32b.

  The suction mechanism 43 is provided on the downstream side of the gas jetted by the air curtain blow jet mechanism 42, and sucks the debris generated near the processing point K while sucking the gas. As shown in FIGS. 4 and 5, the suction mechanism 43 includes a suction port 46 that opens to the partition wall 41, a suction path 47 that communicates with the suction port 46, and a suction source (not shown) that communicates with the suction path 47. Yes. The suction port 46 is disposed on the inner surface (inner side) of the partition wall 41 provided in the lowermost laminated plate 35 a constituting the chamber 32 and below the chamber 32 of the protection means 30. As shown in FIGS. 6 and 7, an opening 32 b below the chamber 32 is provided between the suction port 46 and the jet port 44, and the suction port 46 and the jet port 44 are arranged with a space therebetween. Has been. In the present embodiment, the suction port 46 is opposed to the ejection port 44. The suction path 47 is disposed in the lowermost laminated plate 35a constituting the chamber 32, extends obliquely upward from the suction port 46, and connects the suction port 46 and the suction source. The suction source is connected to the suction port 46 via the suction path 47 and sucks the gas from the suction port 46 via the suction path 47. That is, the suction path 47 is provided on the downstream side of the gas ejected by the air curtain blow ejection mechanism 42 by being sucked by the suction source, and debris generated near the processing point K while sucking the gas. Also suck. It is desirable that the exhaust amount to be exhausted through the suction port 46 and the suction path 47 by the suction force from the suction source is 400 l / min or more.

  Here, the wafer W is a workpiece to be laser processed by the laser processing apparatus 1, and in the present embodiment, is a disk-shaped semiconductor wafer or optical device wafer having silicon, sapphire, gallium or the like as a base material. As shown in FIG. 1, the wafer W includes a plurality of devices formed on the surface WS partitioned by a plurality of streets in a lattice pattern. As shown in FIG. 1, the wafer W has a back surface on the opposite side of the front surface WS on which a plurality of devices are formed attached to the adhesive tape T, and an annular frame F attached to the adhesive tape T attached to the wafer W. By being attached, it is fixed to the annular frame F. On the surface WS of the wafer W, a so-called low-k film (not shown) made of a low-k material (mainly a porous material) is formed as an interlayer insulating film material.

  The control means 90 controls each of the above-described components constituting the laser processing apparatus 1. The control means 90 causes the laser processing apparatus 1 to perform a processing operation on the wafer W. Further, the control means 90 is a protective blow mechanism of the protection means 30 when causing the laser processing apparatus 1 to perform a processing operation on the wafer W, that is, when irradiating the surface WS of the wafer W from the laser beam irradiation means 20. The gas supply source 34 is made to eject gas from the protective ejection port 37, and the gas supply source of the air curtain blow ejection mechanism 42 of the debris discharge means 40 is ejected from the ejection port 44 to the suction source of the suction mechanism 43. The gas is also sucked from the suction port 46. The control means 90 is mainly composed of an arithmetic processing unit constituted by, for example, a CPU, a microprocessor (not shown) provided with a ROM, a RAM, etc., and a display means 83 for displaying the status of the machining operation, and an operator It is connected to an operating means (not shown) used when registering processing content information and the like.

  Next, a laser processing method for the wafer W using the laser processing apparatus 1 according to the embodiment will be described. First, the adhesive tape T is attached to the back surface of the front surface WS on which the device is formed, and the annular frame F is attached to the adhesive tape T. Then, the wafer W adhered to the annular frame F via the adhesive tape T is accommodated in the cassette elevator 50.

  Then, when the operator registers the processing content information in the control means 90 and the operator gives an instruction to start the processing operation, the laser processing apparatus 1 starts the processing operation. In the processing operation, the control means 90 carries out the wafer W before laser processing from the cassette elevator 50 to the temporary placement means 60 by the carry-in / out means 61 in step ST1 in FIG. After being placed thereon, the first transport unit 81 transports the protective film forming and cleaning unit 70 to the spinner table 71 and holds it on the spinner table 71. Then, after the spinner table 71 is lowered, the control means 90 ejects the liquid resin from the coating nozzle onto the wafer W on the spinner table 71 while rotating the spinner table 71 around the central axis. Then, the liquid resin moves to the outer periphery of the wafer W held on the spinner table 71 by centrifugal force. After a predetermined time has elapsed, the spinner table 71 is stopped, and the application of the liquid resin from the application nozzle is stopped. The liquid resin applied to the surface WS of the wafer W is cured, so that the surface WS of the wafer W is covered with the protective film P made of the liquid resin. As described above, step ST1 is a protective film coating step in which the liquid film is applied to the surface WS of the wafer W to form the protective film P. When the covering of the protective film P is completed, the control means 90 raises the spinner table 71 and causes the second transport means 82 to transport the wafer W coated with the protective film P from the spinner table 71 to the chuck table 10. The table 10 is held, and the process proceeds to step ST2.

  Next, the control unit 90 moves the chuck table 10 by the X-axis moving unit and the Y-axis moving unit, positions the wafer W held on the chuck table 10 below the imaging unit, and causes the imaging unit to image. The imaging unit outputs information on the captured image to the control unit 90. Then, the control unit 90 executes image processing such as pattern matching for aligning the street of the wafer W held on the chuck table 10 with the condenser 22 of the laser beam irradiation unit 20 that irradiates the laser beam L. Then, alignment of the laser beam irradiation means 20 is performed, and the process proceeds to step ST3.

  Next, the control unit 90 moves the chuck table 10 by the X-axis moving unit and the Y-axis moving unit based on the alignment information detected in step ST3, and moves the chuck table 10 around the central axis by the base drive source. The laser beam irradiation means 20 is moved by the Z-axis movement means, and one end of a predetermined street is positioned immediately below the condenser 22. Then, the control unit 90 irradiates the chuck table 10 holding the wafer W while irradiating the laser beam L from the condenser 22 of the laser beam irradiating unit 20 to a predetermined street with respect to the laser beam irradiating unit 20 by the X-axis moving unit. And is moved at a predetermined processing speed. Thus, the control means 90 relatively moves the laser beam L in the direction of the arrow X1 (shown in FIGS. 4 and 5) on the surface WS of the wafer W.

  Then, on the predetermined street irradiated with the laser beam L, the wafer W and a part of the protective film P are sublimated, and a processed groove S is formed as shown in FIGS. When the other end of the predetermined street reaches directly under the condenser 22, the irradiation of the laser beam L from the laser beam irradiation means 20 is stopped and the movement of the chuck table 10 by the X-axis movement means is stopped. As described above, the control means 90 sequentially irradiates the streets with the laser beam L, forms the processing grooves S on these streets, and forms the processing grooves S on all the streets of the wafer W. As described above, in step ST3, after performing step ST2, the processing groove formation for forming the processing groove S on the wafer W by irradiating the surface WS of the wafer W with the laser beam L from the protective film P side along the street of the wafer W is performed. There are steps.

  Further, in step ST3 as a processing groove forming step, a gas is supplied from the protective ejection port 37 to the gas supply source of the protective blow mechanism 34 of the protection means 30 while irradiating a predetermined street with the laser beam L to form the processing groove S. Erupt. For this reason, the inside of the chamber 32 is maintained at a positive pressure higher than the outside air. Further, the protective ejection port 37 extends slightly downward from the horizontal as it goes toward the inner surface of the chamber 32, and the plurality of protective ejection ports 37 are evenly arranged around the transparent member 33 without any deviation. Therefore, the gas in the chamber 32 flows downward toward the lower opening 32b evenly around the transparent member 33 without any deviation. That is, a so-called downflow is generated in the chamber 32 of the protection means 30, which faces the lower opening 32 b and is not displaced around the transparent member 33. Furthermore, since the diameter-reduced portion 32c of the chamber 32 is formed in a funnel shape that gradually decreases in diameter toward the lower opening 32b, the flow rate of the above-described downflow increases toward the lower side of the chamber 32. Therefore, an atmosphere containing debris generated near the processing point K by laser processing is prevented from flowing into the chamber 32 from the lower opening 32b.

  Further, in step ST3 as a machining groove forming step, the gas of the air curtain blow ejection mechanism 42 of the debris discharge means 40 is ejected from the protective ejection port 37 to the gas supply source of the protection blow mechanism 34 of the protection means 30. Gas is ejected from the ejection port 44 to the supply source, and gas is suctioned from the suction port 46 to the suction source of the suction mechanism 43. As described above, since the gas is ejected from the ejection port 44 to the gas supply source of the air curtain blow ejection mechanism 42 of the debris discharge means 40, the opening 32b below the chamber 32 is blocked by the gas ejected from the ejection port 44. At the same time, the atmosphere including the debris generated at the processing point K is sucked into the suction source through the suction port 46. Further, since the spout 44 is disposed below the lower opening 32b and spaced from the lower opening 32b, the gas ejected from the spout 44 enters the chamber 32 through the lower opening 32b. Can be suppressed. Since it is possible to suppress the gas ejected from the ejection port 44 from entering the chamber 32 through the lower opening 32b, it is possible to suppress the generation of ascending air current in the chamber 32, and debris enters the chamber 32. This can be reliably suppressed.

  Moreover, since the opening part of the lowermost surface formed and surrounded by the jet nozzle 44 and the inner surface 41a of the partition wall 41 is arranged at intervals, the jetted gas overflows from the suction port 46. Can be suppressed. Thus, in this embodiment, the protection blow mechanism 34 of the protection means 30 and the air curtain blow ejection mechanism 42 of the debris discharge means 40 cooperate to suppress the entry of debris into the chamber 32 from the lower opening 32b. doing. Further, in step ST3 as a processing groove forming step, the jet port 44 is provided in front of the arrow X1, which is a direction in which the laser beam L relatively moves on the surface WS of the wafer W during laser processing, rather than the suction port 46. Therefore, the lower opening 32b is surely blocked by the gas ejected from the ejection port 44, and debris generated near the processing point K by laser processing in the chamber 32 from the lower opening 32b. This will surely prevent the atmosphere containing the inflow.

  When the processing grooves S are formed in all the streets, the control unit 90 moves the chuck table 10 to the vicinity of the protective film forming and cleaning unit 70 by the X-axis driving unit, and moves the chuck table 10 to the second transport unit 82. The wafer W subjected to the above laser processing is placed on the spinner table 71 of the protective film forming and cleaning means 70 and held on the spinner table 71. Then, the controller 90 lowers the spinner table 71 and then causes the cleaning liquid to be ejected from the cleaning nozzle onto the wafer W on the spinner table 71 while rotating the spinner table 71 around the central axis. Then, since the protective film P is made of a water-soluble resin, the protective film P is removed (washed away) from the surface WS of the wafer W together with the debris adhering during the laser processing by the cleaning liquid and the centrifugal force. When the removal of the protective film P is completed, the control unit 90 stops the rotation of the spinner table 71 around the central axis and the supply of the cleaning liquid from the cleaning nozzle, and then raises the spinner table 71 and the first transport unit 81. To the temporary placement means 60. The control means 90 carries the wafer W that has undergone laser processing or the like into the cassette elevator 50 from the temporary placement means 60 by the carry-in / out means 61.

  As described above, according to the laser processing apparatus 1 according to the present embodiment, the air curtain blow jet is performed so as to block the opening 32b below the chamber 32 of the protection means 30 so as to protect the collector 22 from the adhesion of debris. A pressurized gas is ejected from the ejection port 44 of the mechanism 42. Accordingly, debris can be prevented from entering the chamber 32 of the protection means 30 from the lower opening 32b, and the collector 22 is protected from the adhesion of debris, and the transparent member 33 is prevented from adhering to the debris in the atmosphere. The occurrence of cloudiness can be suppressed. Accordingly, it is possible to suppress particularly vaporized debris generated during laser processing from adhering to optical components such as the condenser 22, and also to deteriorate the processing result due to the decrease in the amount of the laser beam L reaching the processing point. Can be prevented.

  Further, since the debris discharge means 40 includes the suction mechanism 43, the debris blown off by the pressurized gas ejected from the ejection port 44 and the side where the debris generated near the processing point K is scattered are scattered. Suction through the suction port 46 and exhaust. Since the lowermost opening portion formed by being surrounded by the inner surface 41a of the partition wall 41 of the debris discharge means 40 has a minimum opening in a range covering the debris scattering range, the scattered debris is protected by the protective means 30 or Adhering to the debris discharge means 40 can be suppressed, and the protection means 30 and the debris discharge means 40 are contaminated by the debris, and the adhering debris hangs down and falls onto the surface WS of the wafer W, thereby suppressing the contamination of the wafer W. Can do.

  Moreover, since it can suppress that a debris adheres to the protection means 30 or the debris discharge means 40, it is also released from the maintenance of removing the attached debris. Further, since the lowermost opening portion formed by being surrounded by the inner surface 41a of the partition wall 41 of the debris discharge means 40 is the minimum opening in a range covering the debris scattering range, the suction force for sucking the debris is efficient. To be demonstrated. Therefore, the laser processing apparatus 1 can suppress debris generated during laser processing from adhering to optical components such as the condenser 22 and the transparent member 33 without performing frequent maintenance.

  In the above-described embodiment, the protective film P is once coated and then laser processing is performed. However, the present invention is not limited to this, and the protective film P may not necessarily be once coated. In the above-described embodiment, the protective film P is formed by curing a liquid resin containing a water-soluble resin such as PVA, PEG, or PEO injected onto the surface WS of the wafer W. However, in the present invention, ablation may be applied to the protective film P without completely curing (drying) the liquid resin. In this case, the protective film P that is not completely dried becomes a large amount of debris. However, in the present invention, since the protective means 30 and the debris discharge means 40 described above are provided, the transparent member 33 is fogged or debris is removed. Adhering to the protection means 30 and the debris discharge means 40 can be prevented. In the present invention, the configurations of the X-axis moving unit, the Y-axis moving unit, and the Z-axis moving unit may be changed as appropriate.

  Furthermore, in the above-described embodiment, the protective blow mechanism 34 of the protection means 30 and the air curtain blow ejection mechanism 42 of the debris discharge means 40 cooperate to suppress the entry of debris into the chamber 32. However, in the present invention, even if the width of the ejection port 44 of the debris discharge means 40 is substantially equal to the width of the lower opening 32b, the gas supply source of the air curtain blow ejection mechanism 42 does not have to provide the protective blow mechanism 34. As long as the gas having a flow rate and flow velocity that can suppress the intrusion of debris into the chamber 32 can be supplied to the ejection port 44, the protective blow mechanism 34 need not be provided.

  The present invention is not limited to the above embodiment. That is, various modifications can be made without departing from the scope of the present invention.

1 Laser processing equipment 10 Chuck table (holding means)
20 Laser beam irradiation means (processing means)
22 collector 30 protection means 32b opening (lower opening)
40 Debris discharge means 41 Bulkhead 42 Air curtain blow jet mechanism 44 Jet port 46 Suction port 47 Suction path K Processing point L Laser beam S Processing groove W Wafer WS Surface

Claims (2)

A holding means for holding a wafer; a processing means having a condenser for irradiating a laser beam on the surface of the wafer held by the holding means to form a processing groove by ablation; and below the condenser Protective means for protecting the collector from debris generated near the processing point by the laser beam disposed and passing through the interior, and debris discharge means for sucking and discharging the debris below the protective means In the laser processing equipment
The debris discharge means is:
A partition wall surrounding a debris scattering range generated near the processing point;
It opens inside the partition and in the vicinity of the lower opening of the protection means, and is disposed below the lower opening, and jets gas in parallel with the surface of the wafer from the direction in which the processing groove is formed. An air curtain blow jet mechanism that has a jet port, covers the lower opening with a gas jetted from the jet port, and blocks entry of the debris into the protection means;
Open to the partition wall and while sucking the said gas at a downstream side of said lower opening interposed therebetween該噴outlet facing the suction port and the suction source and ejected by the air curtain blowing ejection mechanism communicates the the said gas, A suction path for sucking the debris generated near the processing point;
A laser processing apparatus comprising:   2. The laser processing apparatus according to claim 1, wherein the flow velocity of the gas ejected from the ejection port of the air curtain blow ejection mechanism is 600 m / s or more.

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