Laser processing device

Abstract

The present invention provides a laser processing device that effectively removes debris attached to a glass cover and prevents contamination accumulation. The laser processing device (2) has a holding unit (4), a laser light irradiation unit (6), and a feeding unit (30) that relatively processes and feeds the holding unit and the laser light irradiation unit, the laser light irradiation unit has an oscillator (61) that oscillates laser light and a condenser (64) that condenses the laser light, the condenser includes a condensing lens (65), a glass cover (66) that protects the condensing lens from flying debris (110), and an air jet nozzle (80) that sprays air toward the glass cover to remove the debris, the air jet nozzle is composed of a main nozzle (81) that sprays air toward the glass cover and sub nozzles (82-85) that spray air toward the air sprayed from the main nozzle to adjust the spray direction of the air sprayed from the main nozzle.

Description

Technical Field

[0001] This invention relates to laser processing apparatus. Background Technology

[0002] The wafer is divided by predetermined dicing lines to form multiple devices such as ICs and LSIs on the front side. The wafer is divided into individual device chips by a laser processing device and used in electronic devices such as mobile phones and personal computers.

[0003] A laser processing apparatus includes at least: a holding unit for holding a workpiece (e.g., a semiconductor wafer); a laser beam irradiation unit for irradiating the wafer held by the holding unit with laser beams; and a feed unit for feeding the holding unit and the laser beam irradiation unit relative to each other, the laser processing apparatus being capable of performing desired laser processing on the wafer.

[0004] In addition, when a laser beam is irradiated onto a wafer made of silicon, sapphire, or the like, molten material called debris will fly off and contaminate the focusing lens of the focusing unit that constitutes the laser beam irradiation unit. Therefore, in order to prevent debris from entering the focusing lens side, air is supplied to the focusing unit where laser processing is performed to form a downward flow from the focusing lens side to the wafer side (see, for example, Patent Document 1).

[0005] Patent Document 1: Japanese Patent Application Publication No. 2011-121099

[0006] However, the flow rate and velocity of the downward flow generated inside the condenser are limited, making it difficult to completely prevent debris from entering the area where the condenser lens is located from the wafer side. To address this, a glass cover is placed on the outside of the condenser lens to protect it from debris, but the debris attached to the glass cover needs to be removed periodically, resulting in cumbersome operations and reduced productivity. Summary of the Invention

[0007] The present invention was made in view of the above facts, and its main technical problem is to provide a laser processing apparatus that can effectively remove debris attached to a glass cover plate provided to protect a focusing lens, thereby preventing the accumulation of contaminants.

[0008] To address the aforementioned major technical challenges, according to the present invention, a laser processing apparatus is provided, comprising at least: a holding unit for holding a workpiece; a laser beam irradiation unit for irradiating the workpiece held by the holding unit with laser beam; and a feeding unit for feeding the holding unit and the laser beam irradiation unit relative to each other, wherein the laser beam irradiation unit comprises: an oscillator for oscillating laser beam; and a concentrator for converging the laser beam oscillated by the oscillator, the concentrator comprising: a focusing lens; a glass cover for protecting the focusing lens from debris scattered during laser processing of the workpiece; and an air jet nozzle for jetting air toward the glass cover to remove debris, the air jet nozzle having a main nozzle and a secondary nozzle, the main nozzle jetting air toward the glass cover, and the secondary nozzle jetting air toward the air jetted from the main nozzle to adjust the jetting direction of the air jetted from the main nozzle.

[0009] Preferably, the concentrator includes: a cylindrical body surrounding the glass cover and protruding toward the workpiece; and a downflow generating section that supplies air to the interior of the cylindrical body during laser processing to generate a downflow that prevents debris from entering the interior of the cylindrical body. Additionally, a buffer tank is preferably provided in the airflow path supplying air to the secondary nozzle, thereby allowing the direction of the air ejected from the main nozzle to change gradually.

[0010] The laser processing apparatus of the present invention includes at least: a holding unit for holding a workpiece; a laser beam irradiation unit for irradiating the workpiece held by the holding unit with laser beam; and a feeding unit for feeding the holding unit and the laser beam irradiation unit relative to each other. The laser beam irradiation unit includes: an oscillator for oscillating laser beam; and a concentrator for converging the laser beam oscillated by the oscillator. The concentrator includes: a focusing lens; a glass cover for protecting the focusing lens from debris scattered during laser processing of the workpiece; and an air jet nozzle for jetting air toward the glass cover to remove debris. The air jet nozzle has a main nozzle and a secondary nozzle. The main nozzle jets air toward the glass cover, and the secondary nozzle jets air toward the air jetted from the main nozzle, thereby adjusting the jetting direction of the air jetted from the main nozzle. This allows air to be jetted toward a desired area of ​​the glass cover, effectively removing debris scattered and adhering during laser processing. Attached Figure Description

[0011] Figure 1 This is a three-dimensional view of the laser processing equipment.

[0012] Figure 2 It shows the configuration in Figure 1The diagram shows a schematic representation of the optical system of the laser beam irradiation unit of the laser processing apparatus, the air jet nozzle, and the air supply system that supplies air to the air jet nozzle.

[0013] Figure 3 (a) is Figure 2 The end face of the air jet nozzle shown. Figure 3 (b) is Figure 3 Sectional view AA of (a), Figure 3 (c) is Figure 3 (a) BB section view.

[0014] Figure 4 Is Figure 1 A schematic cross-sectional view of the concentrator during laser processing in the laser processing apparatus shown.

[0015] Figure 5 This is a schematic cross-sectional view of the condenser, illustrating an embodiment of the debris removal process for removing debris from the glass cover of the condenser.

[0016] Figure 6 This is a cross-sectional view of an air jet nozzle, showing how high-pressure air is ejected from the main nozzle of the air jet nozzle.

[0017] Figure 7 (a) is a cross-sectional view of the air injection nozzle and a view showing the end face of the air injection nozzle, illustrating the manner in which high-pressure air is injected from the main nozzle and the first auxiliary nozzle of the air injection nozzle. Figure 7 (b) is a cross-sectional view of the air injection nozzle and a view showing the end face of the air injection nozzle, illustrating the manner in which high-pressure air is injected from the main nozzle and the second auxiliary nozzle of the air injection nozzle. Figure 7 (c) is a cross-sectional view of the air injection nozzle and a view showing the end face of the air injection nozzle, illustrating the manner in which high-pressure air is injected from the main nozzle and the third auxiliary nozzle of the air injection nozzle. Figure 7 (d) is a cross-sectional view of the air jet nozzle and a view showing the end face of the air jet nozzle, illustrating the manner in which high-pressure air is injected from the main nozzle and the fourth auxiliary nozzle of the air jet nozzle.

[0018] Label Explanation

[0019] 2: Laser processing device; 3: Base; 4: Holding unit; 6: Laser beam irradiation unit; 60: Optical system; 61: Oscillator; 62: Attenuator; 63: Reflector; 64: Concentrator; 640: Cylinder; 641: Air supply unit; 642: Airflow path for downward flow; 643: Suction flow path; 643a: Suction opening; 644: External gas inlet path; 644a: External gas inlet opening; 65: 66: Condensing lens; 67: Glass cover plate; 68: Annular shoulder; 8: Opening; 8: Air supply system; 80: Air jet nozzle; 80a: Nozzle end face; 81: Main nozzle; 82: First auxiliary nozzle; 83: Second auxiliary nozzle; 84: Third auxiliary nozzle; 85: Fourth auxiliary nozzle; 10: Wafer; 11: Laser processing tank; 21: X-axis movable plate; 22: Y-axis movable plate; 25: Chuck table; 30: Moving single... Element; 31: X-axis feed unit; 32: Y-axis feed unit; 37: Frame; 37a: Vertical wall; 37b: Horizontal wall; 90: Airflow path; 91: First airflow path; 92: Second airflow path; 93: Third airflow path; 94: Fourth airflow path; 95: Fifth airflow path; 96: Sixth airflow path; 97: Seventh airflow path; 110: Debris; 120A~120E: High-pressure air; B 1: Buffer tank 1; B2: Buffer tank 2; B3: Buffer tank 3; B4: Buffer tank 4; F1: Downflow; F2: Recycle flow; VL1: First on / off valve; VL2: Second on / off valve; VL3: Third on / off valve; VL4: Fourth on / off valve; VL5: Fifth on / off valve; VL6: Sixth on / off valve; S1, S2: Space; LB0, LB1: Laser beam; P1, P2: High-pressure air supply source; P3: Suction source. Detailed Implementation

[0020] Hereinafter, embodiments of the laser processing apparatus constructed according to the present invention will be described in detail with reference to the accompanying drawings.

[0021] exist Figure 1 The laser processing apparatus 2 of this embodiment is shown in the figure. The laser processing apparatus 2 includes: a base 3; a holding unit 4 for holding the workpiece; a laser beam irradiation unit 6; an imaging unit 7; a moving unit 30, which is provided as a feed unit for feeding the holding unit 4 and the laser beam irradiation unit 6 relative to each other; and a control unit, which will be described later.

[0022] The holding unit 4 includes: a rectangular movable plate 21 in the X-axis direction, which is movably mounted on the base 3 in the X-axis direction as indicated by arrow X in the figure; a rectangular movable plate 22 in the Y-axis direction, which is movably mounted on the movable plate 21 in the X-axis direction as indicated by arrow Y in the figure; a cylindrical support column 23, which is fixed to the upper surface of the movable plate 22 in the Y-axis direction; and a rectangular cover plate 26, which is fixed to the upper end of the support column 23. A circular chuck worktable 25 extending upward through an elongated hole is provided on the cover plate 26. The chuck worktable 25 is configured to be rotated by a rotary drive unit (not shown). The holding surface 25a of the upper surface of the chuck worktable 25, defined by the X-axis and Y-axis coordinates, is formed of a porous material and is ventilated. It is connected to the suction unit (not shown) via a flow path passing through the interior of the support column 23.

[0023] The moving unit 30 includes: an X-axis feed unit 31, mounted on the base 3, which feeds the holding unit 4 in the X-axis direction; and a Y-axis feed unit 32, which indexes the movable plate 22 in the Y-axis direction. The X-axis feed unit 31 converts the rotational motion of the pulse motor 33 into linear motion via a ball screw 34 and transmits it to the movable plate 21 in the X-axis direction, causing the movable plate 21 to move forward and backward along the guide rails 3a, 3a on the base 3 in the X-axis direction. The Y-axis feed unit 32 converts the rotational motion of the pulse motor 35 into linear motion via a ball screw 36 and transmits it to the movable plate 22 in the Y-axis direction, causing the movable plate 22 to move forward and backward along the guide rails 21a, 21a on the movable plate 21 in the X-axis direction. Furthermore, although not shown in the diagram, position detection units are provided in the X-axis feed unit 31, the Y-axis feed unit 32, and the chuck table 25 to accurately detect the X-axis coordinates, Y-axis coordinates, and circumferential rotational position of the chuck table 25. This position information is sent to the control unit of the laser processing apparatus 2. Furthermore, by receiving an instruction signal from the control unit based on this position information, the rotation drive units of the X-axis feed unit 31, the Y-axis feed unit 32, and the chuck table 25 (not shown) are driven, thereby positioning the chuck table 25 at the desired position on the base 3.

[0024] like Figure 1 As shown, a frame 37 is erected on the side of the moving unit 30. The frame 37 has: a vertical wall 37a, which is disposed on the base 3 and arranged along the Z-axis, which is perpendicular to the X-axis and Y-axis directions; and a horizontal wall 37b, which extends horizontally from the upper end of the vertical wall 37a. The optical system 60 of the laser beam irradiation unit 6 (described later) is housed inside the horizontal wall 37b of the frame 37. Figure 2A condenser 64, which forms part of the optical system 60, is disposed on the lower surface of the front end of the horizontal wall portion 37b. An air supply unit 641 is formed on the lower end side of the condenser 64 to supply air into the interior of the condenser 64. An air supply system 8 (see reference 8) supplies air to the air supply unit 641. Figure 2 It is also housed inside the horizontal wall portion 37b. Furthermore, the air supply unit 641 has multiple airflow paths connected for supplying and discharging air, but... Figure 1 Omitted in .

[0025] The imaging unit 7 is disposed on the lower surface of the front end of the horizontal wall portion 37b, and is positioned at a distance from the condenser 64 of the laser beam irradiation unit 6 in the X-axis direction. The imaging unit 7 includes: a conventional imaging element (CCD) for capturing images using visible light; an infrared irradiation unit for irradiating infrared light; and an imaging element (infrared CCD) that captures infrared light irradiated by the infrared irradiation unit and reflected on the chuck stage 25, and outputs an electrical signal corresponding to that infrared light. The image captured by the imaging unit 7 is sent to the control unit and displayed on a suitable display unit (not shown).

[0026] exist Figure 1 The image shows a wafer 10, prepared as a workpiece for processing according to this embodiment, together with the laser processing apparatus 2, and an annular frame F that holds the wafer 10 by means of a protective strip T having an adhesive layer. The wafer 10 is, for example, a silicon wafer with a thickness of 700 μm, on which multiple devices are formed by dividing predetermined lines on the front side.

[0027] exist Figure 2 A schematic cross-section of the concentrator 64 that constitutes the laser beam irradiation unit 6. Figure 1 An optical system 60 that directs laser beams to a concentrator 64 and an air supply system 8 that supplies air to an air supply unit 641 of a laser beam irradiation unit 6 are shown. The structures of each are described below.

[0028] The laser beam irradiation unit 6 includes at least an oscillator 61 that oscillates to emit pulsed laser beams LB0 and a concentrator 64. Figure 2As shown in the cross-sectional view, the concentrator 64 has a cylindrical body 640 protruding towards the workpiece side (lower direction in the figure) in the Z-axis direction (vertical direction) indicated by arrow Z, and an air supply unit 641 constituting the lower side of the cylindrical body 640. A condensing lens 65 is held inside the cylindrical body 640, and a glass cover 66, surrounded and held by the cylindrical body 640, is disposed on the workpiece side of the condensing lens 65. Furthermore, the laser beam irradiation unit 6 of this embodiment includes: an attenuator 62 that adjusts the laser beam LB0 to an appropriate output; and a reflector 63 that modifies the optical path of the laser beam LB1 whose output has been adjusted by the attenuator 62. The laser beam LB1 reflected by the reflector 63 is converged by the condensing lens 65 disposed in the concentrator 64 and irradiates the workpiece positioned below the concentrator 64. The glass cover 66 protects the focusing lens 65 from debris that flies out during the laser beam LB1's transmission and laser processing of the workpiece. Inside the air supply unit 641 of the cylinder 640, an air jet nozzle 80 is provided in the space S1 through which the laser beam LB1 passes through the glass cover 66. The air jet nozzle 80 sprays air from a downward angle toward the glass cover 66 to remove debris adhering to the glass cover 66.

[0029] Reference Figure 2 , Figure 3 The air injection nozzle 80 described above will be explained in more detail. Figure 3 Figure (a) shows a view taken from the end face 80a side of the air injection nozzle 80. Figure 3 (b) shows that Figure 3 The AA section obtained by cutting AA in (a) is in Figure 3 (c) shows that Figure 3 The BB section obtained by cutting the BB of (a). Figure 3 The section AA shown in (b) is a longitudinal sectional view cut through the center of the end face 80a of the air injection nozzle 80 and along the axis of the air injection nozzle 80 in a vertical direction. Figure 3 The BB section shown in (c) is a cross-sectional view cut along the axis from the front end of the air injection nozzle 80 through the center of the end face 80a of the air injection nozzle 80 while maintaining horizontality.

[0030] Depend on Figure 3 (a)~ Figure 3(c) It can be understood that a large-diameter main nozzle 81 is formed at the center of the end face 80a of the air injection nozzle 80. Four auxiliary nozzles, namely the first auxiliary nozzle 82, the second auxiliary nozzle 83, the third auxiliary nozzle 84, and the fourth auxiliary nozzle 85, are arranged around the main nozzle 81. These auxiliary nozzles are formed with smaller diameters compared to the main nozzle 81 and are arranged at equal intervals in the circumferential direction. The main nozzle 81 is directed towards the center of the glass cover 66, and the front ends of each auxiliary nozzle are inclined towards the axis C of the main nozzle 81 (=the axis of the air injection nozzle 80).

[0031] return Figure 2 This describes an air supply system 8 that supplies air to an air injection nozzle 80. The air supply system 8 includes: a high-pressure air supply source P1 that supplies high-pressure air; and an air flow path 90 that supplies air from the high-pressure air supply source P1 to the air injection nozzle 80. The air flow path 90 includes: a first air flow path 91 that supplies air to the main nozzle 81 of the air injection nozzle 80; a second air flow path 92 that supplies air to a first auxiliary nozzle 82; a third air flow path 93 that supplies air to a second auxiliary nozzle 83; a fourth air flow path 94 that supplies air to a third auxiliary nozzle 84; and a fifth air flow path 95 that supplies air to a fourth auxiliary nozzle 85.

[0032] A first on / off valve VL1 is provided on the first air flow path 91 to open and close the first air flow path 91; a second on / off valve VL2 is provided on the second air flow path 92 to open and close the second air flow path 92; a third on / off valve VL3 is provided on the third air flow path 93 to open and close the third air flow path 93; a fourth on / off valve VL4 is provided on the fourth air flow path 94 to open and close the fourth air flow path 94; and a fifth on / off valve VL5 is provided on the fifth air flow path 95 to open and close the fifth air flow path 95. A first buffer tank B1 is disposed between the second on / off valve VL2 and the first auxiliary nozzle 82 on the second air flow path 92; a second buffer tank B2 is disposed between the third on / off valve VL3 and the second auxiliary nozzle 83 on the third air flow path 93; a third buffer tank B3 is disposed between the fourth on / off valve VL4 and the third auxiliary nozzle 84 on the fourth air flow path 94; and a fourth buffer tank B4 is disposed between the fifth on / off valve VL5 and the fourth auxiliary nozzle 85 on the fifth air flow path 95. Each buffer tank has the function of accumulating pressure on a portion of the high-pressure air supplied through each air flow path, and thus functions as follows: when high-pressure air is first supplied through each air flow path, it moderates the rise in injection pressure of the high-pressure air injected from each auxiliary nozzle; and after high-pressure air is stopped being supplied from each air flow path, it gradually reduces the injection pressure of the high-pressure air injected from each auxiliary nozzle. In addition, valves 1 to 5, VL1 to VL5, are normally closed valves that are closed under normal conditions. They are opened at specified times according to the instruction signals of the control program stored in the control unit 100.

[0033] The air supply unit 641 provided in the condenser 64 of this embodiment also functions as a downflow generating unit, which suppresses the occurrence of debris flying off during the processing of the wafer 10 and entering the glass cover 66 side. More specifically, as Figure 2As shown, a downflow generating airflow path 642 is formed in the air supply unit 641 of the concentrator 64. A sixth airflow path 96 for supplying high-pressure air from the high-pressure air supply source P2 is connected to the downflow generating airflow path 642. A sixth on / off valve VL6 for opening and closing the sixth airflow path 96 is provided on the sixth airflow path 96. The sixth on / off valve VL6 is a normally closed valve, connected to the control unit 100, and is opened according to the command signal output from the control unit 100. Inside the cylinder 640 that supports the glass cover 66, an annular shoulder 67 with an opening 68 in the center is formed below the glass cover 66. An annular space S2 is formed between the glass cover 66 and the annular shoulder 67. High-pressure air supplied via the sixth airflow path 96 passes through the descending airflow path 642, is supplied from the side of the glass cover 66 to the aforementioned annular space S2, and is discharged as a descending flow from the opening 68 into the space S1 below which the air jet nozzle 80 is provided.

[0034] Additionally, an suction flow path 643 and an external gas inlet path 644 are formed in the air supply unit 641, with one end of each of the suction flow path 643 and the external gas inlet path 644 opening in the space S1 below. A suction source P3, which provides negative pressure via a seventh air flow path 97, is connected to the other end of the suction flow path 643. A seventh on / off valve VL7 is provided on the seventh air flow path 97 to open and close it. The other end of the external gas inlet path 644 opens to the outside to introduce external gas A. The seventh on / off valve VL7 is a normally closed valve, connected to the control unit 100, and is opened according to a command signal output from the control unit 100. One end of the suction flow path 643 has an arc-shaped suction opening 643a (not shown) that is elongated in the horizontal direction on the inner wall surface of the space S1. Additionally, at one end of the external gas inlet passage 644, on the inner wall surface forming the space S1, at a position opposite to the aforementioned suction opening 643a, an external gas inlet opening 644a, which is elongated in the horizontal direction (not shown), is formed. When the high-pressure air supplied via the sixth airflow passage 96 forms a downward flow into the space S1 from the opening 68, the aforementioned suction source P3 is activated, and the seventh opening / closing valve VL7 is opened. This allows debris 110 contained in the downward flow flowing into the space S1 below to be drawn in through the suction opening 643a without the debris 110 leaking to the outside.

[0035] The laser processing apparatus 2 of this embodiment has a structure generally as described above, and its functions and effects will be explained below.

[0036] First, the following operation will be explained: When laser processing is performed on the front side of the wafer 10 using the laser processing apparatus 2 described above, the air supply unit 641 of the laser beam irradiation unit 6 functions as a downflow generation unit.

[0037] First of all, Figure 1 The laser processing apparatus 2 shown has a chuck stage 25 on which a wafer 10, supported by a protective strap T and held in place by suction. Next, the moving unit 30 is activated to position the chuck stage 25 below the imaging unit 7, and the wafer 10 is imaged from above for alignment. The processing position on the wafer 10 to be laser-processed (e.g., the position of a pre-defined dividing line for a dividing device) is detected, and the position information of that processing position is recorded in the control unit 100.

[0038] Based on the position information detected through the alignment, the moving unit 30 is made to perform an action, such as... Figure 4 As shown, the concentrator 64 of the laser beam irradiation unit 6 is positioned above the location where laser processing is performed on the wafer 10. Next, the sixth and seventh on / off valves VL6 and VL7 are opened, and the high-pressure air supply source P2 and the suction source P3 are activated, generating a descending flow F1 flowing towards the space S1 below the air supply unit 641. A recovery flow F2, flowing from the external gas inlet 644a to the suction opening 643a, is formed below this space S1. Next, the concentrator 64 is activated, positioning the focal point of the laser beam LB1 on the front surface 10a of the wafer 10. The laser beam irradiation unit 6 is activated to irradiate the laser beam LB1, and while the moving unit 30 acts as a feed unit to feed the chuck stage 25 in the direction indicated by arrow X, a laser processing groove 11 is formed on the front surface 10a of the wafer 10.

[0039] In addition, the laser processing conditions for performing the above-mentioned laser processing are set as follows.

[0040] Wavelength: 355nm

[0041] Repetition frequency: 50kHz

[0042] Average output: 4W

[0043] Machining feed rate: 150 mm / s

[0044] By performing the laser processing described above, a laser processing groove 11 is formed on the front side 10a of the wafer 10. During this process, granular debris 110 formed from molten silicon is generated and dispersed upwards. This debris 110 enters the interior of the concentrator 64, but as described above, a downward flow F1 is generated in the space S1 below the interior of the air supply unit 641. As a result, almost all of the upward-dispersed debris 110 does not reach the glass cover 66 but is guided downwards and recovered by the recovery flow F2 flowing below the air supply unit 641, which is then returned to the suction flow path 643. Furthermore, although not shown in the figure, an air filter is provided on the seventh air flow path 97 connected to the suction flow path 643 to recover the attracted debris 110. In this way, the air supply unit 641 of the concentrator 64 functions as a downward flow generation unit, thereby preventing the debris 110 dispersed during laser processing from adhering to the glass cover 66, and allowing the dispersed debris 110 to be recovered in the seventh air flow path 97. While the moving unit 30, which feeds the chuck table 25, is activated, laser processing is performed on all designated processing positions on the wafer 10, thereby completing the laser processing of the wafer 10 while recovering the debris 110 scattered from the processing positions.

[0045] While laser processing, as described above, can suppress the adhesion of debris 110 to the glass cover plate 66 to some extent, even if it produces... Figure 4 The downward flow F1 shown is also insufficient to completely prevent contamination caused by debris 110. Therefore, after performing the aforementioned laser processing a predetermined number of times, a debris removal process, as described below, is performed at any time to remove debris 110 from the glass cover plate 66. (Refer to...) Figure 1 , Figure 2 as well as Figures 5-7 The debris removal process will be explained.

[0046] During the debris removal process, the moving unit 30 is activated, causing the chuck stage 25 to move to the loading / unloading position where the wafer 10 is loaded / unloaded relative to the chuck stage 25. Figure 1 (The position of the chuck worktable 25). Next, in Figure 2 With the sixth on / off valve VL6 closed, the high-pressure air supply source P2 is stopped, and the seventh on / off valve VL7 is opened, causing the suction source P3 to operate. Next, the high-pressure air supply source P1 is operated, and the first on / off valve VL1 is opened. Thus, the air jet nozzle 80 is shown in section AA of its end face 80a. Figure 6It is understood that high-pressure air is supplied to the air injection nozzle 80 only via the first air flow path 91 in the air flow path 90, and high-pressure air 120A is injected only from the main nozzle 81. The injected high-pressure air 120A travels straight along the axis C of the main nozzle 81, such as... Figure 5 As shown, the air is blown to approximately the center of the glass cover 66, causing the debris 110 adhering to the central region of the glass cover 66 to detach and fall off. The debris 110 detached from the central region of the glass cover 66 falls into the space S1 and is drawn by the suction flow path 643 along with the flow of the recovery flow F2 formed by the suction opening 643a and the external gas introduction opening 644a, and is recovered via the seventh air flow path 97.

[0047] If, as described above, high-pressure air 120A is injected for a predetermined time from the main nozzle 81 of the air injection nozzle 80, then, with the first on / off valve VL1 open (i.e., with high-pressure air 120A being injected directly from the main nozzle 81), the second on / off valve VL2 is opened. Thus, as shown in the AA cross-section of the end face 80a of the air injection nozzle 80... Figure 7 As shown in (a), high-pressure air is introduced into the second airflow path 92 and ejected from the first auxiliary nozzle 82. As described above, the first auxiliary nozzle 82 is inclined toward the axis C of the main nozzle 81, and the high-pressure air ejected from the first auxiliary nozzle 82 is directed toward the high-pressure air 120A ejected from the main nozzle 81. As a result, the high-pressure air 120A ejected from the main nozzle 81 becomes high-pressure air 120B adjusted to be ejected along the direction C1 from the first auxiliary nozzle 82. The direction of ejecting this high-pressure air 120B is as follows... Figure 7 The right side of (a) shows the direction toward the third auxiliary nozzle 84, where high-pressure air 120B is located. Figure 5 During observation, the air is sprayed onto the area of ​​the glass cover 66 away from the air jet nozzle 80 (to the right in the figure). However, in this embodiment, a first buffer tank B1 is provided on the second air flow path 92 as described above. As a result, through the action of the first buffer tank B1, the jet pressure of the high-pressure air ejected from the first auxiliary nozzle 82 gradually increases, and the direction of the high-pressure air 120A ejected from the main nozzle 81 of the air jet nozzle 80 is adjusted so that it switches to high-pressure air 120B smoothly rather than abruptly. Therefore, the area in the glass cover 66 between the area where high-pressure air 120A was previously strongly blown and the area where high-pressure air 120B is about to be strongly blown is also sufficiently blown with high-pressure air, thereby effectively removing the debris 110 adhering to the glass cover 66.

[0048] If the high-pressure air 120B is injected from the air injection nozzle 80 for a predetermined period of time, the second on / off valve VL2 is closed, and the third on / off valve VL3, which is provided in the third air flow path 93, is opened. This stops the supply of high-pressure air to the second air flow path 92, as shown by the BB cross-section of the end face 80a of the air injection nozzle 80. Figure 7 (b) can be understood as introducing high-pressure air into the third airflow path 93 and injecting high-pressure air from the second auxiliary nozzle 83. The result is that, towards... Figure 7 The high-pressure air 120B is ejected in the direction C1 shown in (a). Figure 7 (b) shows high-pressure air 120C being adjusted to be injected in the direction C2 along the direction from the second auxiliary nozzle 83. The direction of injection of this high-pressure air 120C is as follows: Figure 7 The right side of (b) shows the direction from the second auxiliary nozzle 83 toward the fourth auxiliary nozzle 85, where high-pressure air 120C is injected towards the direction indicated. Figure 5 The region on the inside of the glass cover 66 in the Y-axis direction (the direction perpendicular to the paper plane). However, in this embodiment, the second buffer tank B2 is also provided on the third air flow path 93 as described above. Therefore, when the second on / off valve VL2 is closed and the third on / off valve VL3 provided in the third air flow path 93 is opened, the injection pressure of the high-pressure air injected from the first auxiliary nozzle 82 gradually decreases and the injection pressure of the high-pressure air injected from the second auxiliary nozzle 83 gradually increases due to the action of the first buffer tank B1 and the second buffer tank B2. Therefore, the high-pressure air 120B injected from the air injection nozzle 80 is adjusted so that it switches to high-pressure air 120C smoothly rather than abruptly. Therefore, in the glass cover 66, the area between the region where high-pressure air 120B was previously strongly blown and the region where high-pressure air 120C is about to be strongly blown is also sufficiently blown with high-pressure air, thereby effectively removing the debris 110 adhering to the glass cover 66 in this area.

[0049] Furthermore, if the aforementioned high-pressure air 120C is injected from the air injection nozzle 80 for a predetermined period of time, the fourth opening / closing valve VL4, located in the fourth air flow path 94, is opened simultaneously with the closing of the third opening / closing valve VL3. This stops the supply of high-pressure air to the third air flow path 93, as shown in the AA cross-section of the end face 80a of the air injection nozzle 80. Figure 7 As shown in (c), high-pressure air is introduced into the fourth airflow path 94, and this high-pressure air is injected from the third auxiliary nozzle 84. The result is that, towards... Figure 7 (b) shows the direction of the high-pressure air ejected from C2 at 120°C. Figure 7As shown in (c), the high-pressure air 120D is adjusted to be injected in the direction C3 along the direction of the jet from the third auxiliary nozzle 84. The direction of the high-pressure air 120D is as follows: Figure 7 The right side of (c) shows the direction from the third auxiliary nozzle 84 toward the first auxiliary nozzle 82, where the high-pressure air 120D is injected. Figure 5 The area on the side (left side in the figure) of the glass cover 66 shown, in the X-axis direction, is where the air injection nozzle 80 is arranged. However, in this embodiment, the third buffer tank B3 is also arranged on the fourth air flow path 94 as described above. Therefore, when the third on / off valve VL3 is closed and the fourth on / off valve VL4 arranged in the fourth air flow path 94 is opened, the injection pressure of the high-pressure air injected from the second auxiliary nozzle 83 gradually decreases and the injection pressure of the high-pressure air injected from the third auxiliary nozzle 84 gradually increases due to the action of the second buffer tank B2 and the third buffer tank B3. Therefore, the high-pressure air 120C injected from the air injection nozzle 80 is adjusted so that it switches to high-pressure air 120D smoothly rather than abruptly. Therefore, in the glass cover 66, the area between the area where high-pressure air 120C was previously strongly blown and the area where high-pressure air 120D is about to be strongly blown is also sufficiently blown with high-pressure air, thereby effectively removing the debris 110 adhering to the glass cover 66 in this area.

[0050] Furthermore, if the aforementioned high-pressure air 120D is injected from the air injection nozzle 80 for a predetermined period of time, the fifth opening / closing valve VL5, located in the fifth air flow path 95, is opened simultaneously with the fourth opening / closing valve VL4 being closed. This stops the supply of high-pressure air to the fourth air flow path 94, as shown by the BB cross-section of the end face 80a of the air injection nozzle 80. Figure 7 As shown in (d), high-pressure air is introduced into the fifth airflow path 95 and injected from the fourth auxiliary nozzle 85. The result is that, towards... Figure 7 The high-pressure air 120D injected by C3 in the direction shown in (c) Figure 7 As shown in (d), the high-pressure air 120E is adjusted to be injected in the direction C4 along the direction from the fourth auxiliary nozzle 85. The direction of injection of this high-pressure air 120E is as follows: Figure 7 The right side of (d) shows the direction from the fourth auxiliary nozzle 85 toward the second auxiliary nozzle 83, where the high-pressure air 120E is... Figure 5 Spraying into the glass cover 66 shown to point Figure 5The area near the front side of the paper described. However, in this embodiment, the fourth buffer tank B4 is also provided on the fifth air flow path 95 as described above. Therefore, when the fourth on / off valve VL4 is closed and the fifth on / off valve VL5 provided in the fifth air flow path 95 is opened, the injection pressure of the high-pressure air injected from the third auxiliary nozzle 84 gradually decreases and the injection pressure of the high-pressure air injected from the fourth auxiliary nozzle 85 gradually increases due to the action of the third buffer tank B3 and the fourth buffer tank B4. Therefore, the high-pressure air 120D injected from the air injection nozzle 80 is adjusted so that it does not switch to high-pressure air 120E abruptly but gradually. Therefore, the area in the glass cover 66 between the area where high-pressure air 120D was previously strongly blown and the area where high-pressure air 120E is about to be strongly blown is also sufficiently blown with high-pressure air, thereby effectively removing the debris 110 adhering to the glass cover 66 in this area.

[0051] Therefore, the high-pressure air ejected from the air jet nozzle 80 changes direction according to C→C1→C2→C3→C4, and is sequentially sprayed onto the desired area of ​​the glass cover 66, resulting in uniform spraying across the entire area of ​​the glass cover 66. This effectively removes debris 110 adhering to the glass cover 66. Furthermore, buffer tanks are provided in the airflow path 90 that supplies high-pressure air to each auxiliary nozzle, so the direction of the high-pressure air ejected from the air jet nozzle 80 changes gradually. Therefore, the intermediate area during the change of direction of the high-pressure air ejected from the air jet nozzle 80 according to C→C1→C2→C3→C4 is also sufficiently sprayed with high-pressure air, thereby overcoming the problem of debris 110 remaining on the front side of the glass cover 66.

[0052] In the above embodiment, four secondary nozzles are arranged at equal intervals in the outer peripheral region of the main nozzle 81 forming the air jet nozzle 80. However, the present invention is not limited to this, and the number of secondary nozzles can be arbitrarily set. However, in order to jet high-pressure air over the entire area of ​​the glass cover 66, it is preferable to arrange three or more secondary nozzles surrounding the main nozzle 81.

[0053] In addition, in the above embodiment, the direction of the high-pressure air ejected from the air jet nozzle 80 is changed in the order of C→C1→C2→C3→C4, and it is sequentially sprayed onto the desired area of ​​the glass cover 66. However, this action can be repeated multiple times to further reduce the amount of debris 110 remaining on the glass cover 66.

[0054] In addition, in the above embodiments, high-pressure air supply source P1 and high-pressure air supply source P2 are prepared respectively, but the present invention is not limited to this, and a single high-pressure air supply source P1 can also be used.

Claims

1. A laser processing apparatus, comprising at least: a holding unit that holds a workpiece; a laser beam irradiation unit that irradiates a laser beam to the workpiece held by the holding unit; and a feeding unit that relatively feeds the holding unit and the laser beam irradiation unit, wherein the laser beam irradiation unit has: an oscillator that oscillates a laser beam; and a condenser that condenses the laser beam oscillated by the oscillator, the condenser includes: a condensing lens; a glass cover that protects the condensing lens from debris scattered when the workpiece is laser processed; and an air jet nozzle that jets air toward the glass cover to remove the debris, the air jet nozzle has a main nozzle that jets air toward the glass cover and a sub nozzle that jets air toward air jetted from the main nozzle to adjust a jet direction of air jetted from the main nozzle, a surge tank that accumulates a portion of air supplied through an air flow path that supplies air to the sub nozzle is provided in the air flow path, so that a jet pressure of air jetted from the sub nozzle is slowly changed, thereby gently changing the direction of air jetted from the main nozzle.

2. The laser processing apparatus according to claim 1, wherein the condenser has: a cylinder that surrounds the glass cover and projects toward the workpiece side; and a downflow generation portion that generates a downflow by supplying air to the inside of the cylinder when the workpiece is laser processed, the downflow preventing the debris from entering the inside of the cylinder. ​

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