JP7473429B2 - Laser processing equipment - Google Patents

Description

The present invention relates to a laser processing device.

Wafer surfaces are divided into multiple IC, LSI and other devices along planned division lines, and are then divided into individual device chips by a laser processing machine for use in electronic devices such as mobile phones and personal computers.

The laser processing device is equipped with at least a holding means for holding a workpiece (e.g., a semiconductor wafer), a laser beam application means for applying a laser beam to the wafer held by the holding means, and a feed means for feeding the holding means and the laser beam application means relatively for processing, and can perform the desired laser processing on the wafer.

In addition, when a wafer made of silicon, sapphire, or the like is irradiated with a laser beam, molten material called debris scatters and contaminates the focusing lens of the focusing device that constitutes the laser beam irradiation means. Therefore, in order to prevent the debris from entering the focusing lens side, air is supplied to the focusing device performing the laser processing, forming a downflow that flows from the focusing lens side to the wafer side (see, for example, Patent Document 1).

JP 2011-121099 A

However, there is a limit to the flow rate and speed of the downflow generated inside the collector, and it is difficult to completely prevent debris from entering the area where the collector lens is located from the wafer side. In response to this, a cover glass is placed on the outside of the collector lens to protect it from debris, but debris adhering to the cover glass must be periodically removed, which is a cumbersome task and reduces productivity.

The present invention has been made in consideration of the above facts, and its main technical objective is to provide a laser processing device that can effectively remove debris that has adhered to a cover glass that is arranged to protect the focusing lens, and can prevent the accumulation of contamination.

In order to solve the above-mentioned main technical problem, according to the present invention, a laser processing device is provided that includes at least a holding means for holding a workpiece, a laser beam application means for applying a laser beam to the workpiece held by the holding means, and a feed means for relatively feeding the holding means and the laser beam application means, the laser beam application means including an oscillator for emitting a laser beam and a condenser for focusing the laser beam emitted by the oscillator, the condenser including a condensing lens, a cover glass for protecting the condensing lens from debris scattered during laser processing of the workpiece, and an air injection nozzle for injecting air toward the cover glass to remove the debris, the air injection nozzle including a main nozzle and a sub-nozzle, the main nozzle injects air toward the cover glass, and the sub-nozzle injects air toward the air injected from the main nozzle, thereby adjusting the injection direction of the air injected from the main nozzle.

The collector preferably includes a cylinder that surrounds the cover glass and protrudes toward the workpiece, and a downflow generating unit that supplies air to the inside of the cylinder during laser processing to generate a downflow that prevents debris from entering the inside of the cylinder. It is also preferable that a buffer tank is disposed in the air flow path that supplies air to the sub-nozzle, and that the direction of the air sprayed from the main nozzle is smoothly changed.

The laser processing device of the present invention is a laser processing device that includes at least a holding means for holding a workpiece, a laser beam application means for applying a laser beam to the workpiece held by the holding means, and a feed means for relatively feeding the holding means and the laser beam application means for processing. The laser beam application means includes an oscillator for emitting a laser beam and a condenser for focusing the laser beam emitted by the oscillator. The condenser includes a condensing lens, a cover glass for protecting the condensing lens from debris scattered during laser processing of the workpiece, and an air injection nozzle for injecting air toward the cover glass to remove the debris. The air injection nozzle includes a main nozzle and a sub-nozzle. The main nozzle injects air toward the cover glass, and the sub-nozzle adjusts the injection direction of the air injected from the main nozzle by injecting air toward the air injected from the main nozzle. Therefore, air can be injected into a desired area of the cover glass to effectively remove debris that has been scattered and attached during laser processing.

FIG. 2 is an overall perspective view of the laser processing device. 2 is a conceptual diagram showing an outline of an optical system of a laser beam application means, an air injection nozzle, and an air supply system that supplies air to the air injection nozzle, which are arranged in the laser processing apparatus shown in FIG. 1. 3A is an end face of the air injection nozzle shown in FIG. 2, FIG. 3B is a cross-sectional view taken along line AA of FIG. 2A, and FIG. 3C is a cross-sectional view taken along line BB of FIG. 2 is a schematic cross-sectional view of a collector when performing laser processing in the laser processing apparatus shown in FIG. 1. 1 is a schematic cross-sectional view of a collector illustrating an embodiment of a debris removal process for removing debris from a cover glass of the collector. FIG. 4 is a cross-sectional view showing a mode in which high-pressure air is ejected from a main nozzle of an air ejection nozzle. FIG. 1A is a cross-sectional view showing how high-pressure air is ejected from the main nozzle and first sub-nozzle of the air injection nozzle, and an end face of the air injection nozzle; (b) a cross-sectional view showing how high-pressure air is ejected from the main nozzle and second sub-nozzle of the air injection nozzle, and an end face of the air injection nozzle; (c) a cross-sectional view showing how high-pressure air is ejected from the main nozzle and third sub-nozzle of the air injection nozzle, and an end face of the air injection nozzle; (d) a cross-sectional view showing how high-pressure air is ejected from the main nozzle and fourth sub-nozzle of the air injection nozzle, and an end face of the air injection nozzle.

The following describes in detail an embodiment of a laser processing device constructed according to the present invention, with reference to the attached drawings.

Figure 1 shows a laser processing device 2 according to this embodiment. The laser processing device 2 includes a base 3, a holding means 4 for holding the workpiece, a laser beam application means 6, an imaging means 7, a moving means 30 arranged as a feed means for relatively feeding the holding means 4 and the laser beam application means 6 for processing, and a control means which will be described later.

The holding means 4 includes a rectangular X-axis direction movable plate 21 mounted on the base 3 so as to be movable in the X-axis direction indicated by the arrow X in the figure, a rectangular Y-axis direction movable plate 22 mounted on the X-axis direction movable plate 21 so as to be movable in the Y-axis direction indicated by the arrow Y in the figure, a cylindrical support 23 fixed to the upper surface of the Y-axis direction movable plate 22, and a rectangular cover plate 26 fixed to the upper end of the support 23. A circular chuck table 25 extending upward through a long hole is disposed on the cover plate 26, and the chuck table 25 is configured to be rotatable by a rotation drive means (not shown). The holding surface 25a, which is defined by the X-axis coordinate and the Y-axis coordinate constituting the upper surface of the chuck table 25, is made of a porous material and has air permeability, and is connected to a suction means (not shown) by a flow path passing through the inside of the support 23.

The moving means 30 is provided on the base 3 with an X-axis feed means 31 for feeding the holding means 4 in the X-axis direction for processing, and a Y-axis feed means 32 for indexing and feeding the Y-axis movable plate 22 in the Y-axis direction. The X-axis feed means 31 converts the rotational motion of the pulse motor 33 into linear motion via a ball screw 34 and transmits it to the X-axis movable plate 21, and moves the X-axis movable plate 21 forward and backward in the X-axis direction along the guide rails 3a, 3a on the base 3. The Y-axis feed means 32 converts the rotational motion of the pulse motor 35 into linear motion via a ball screw 36 and transmits it to the Y-axis movable plate 22, and moves the Y-axis movable plate 22 forward and backward in the Y-axis direction along the guide rails 21a, 21a on the X-axis movable plate 21. Although not shown, the X-axis feed means 31, the Y-axis feed means 32, and the chuck table 25 are provided with position detection means, which accurately detect the X-axis coordinate, the Y-axis coordinate, and the circumferential rotational position of the chuck table 25, and the position information is sent to the control means of the laser processing device 2. Then, the control means issues an instruction signal based on the position information to drive the X-axis feed means 31, the Y-axis feed means 32, and the rotation drive means of the chuck table 25 (not shown), so that the chuck table 25 can be positioned at the desired position on the base 3.

As shown in FIG. 1, a frame 37 is erected on the side of the moving means 30. The frame 37 is provided with a vertical wall 37a arranged on the base 3 along the Z axis perpendicular to the X-axis direction and the Y-axis direction, and a horizontal wall 37b extending horizontally from the upper end of the vertical wall 37a. The horizontal wall 37b of the frame 37 houses an optical system 60 (see FIG. 2) of the laser beam application means 6, which will be described later, and a condenser 64 constituting a part of the optical system 60 is disposed on the lower surface of the tip of the horizontal wall 37b. An air supply unit 641 that supplies air to the condenser 64 is formed on the lower end side of the condenser 64. An air supply system 8 (see FIG. 2) that supplies air to the air supply unit 641 is also housed inside the horizontal wall 37b. Note that a plurality of air flow paths are connected to the air supply unit 641 to supply and discharge air, but are omitted in FIG. 1.

The imaging means 7 is disposed on the underside of the tip of the horizontal wall portion 37b, at a position spaced apart in the X-axis direction from the condenser 64 of the laser beam application means 6. The imaging means 7 includes a normal imaging element (CCD) that captures images using visible light, an infrared irradiation means that irradiates infrared rays, an imaging element (infrared CCD) that captures infrared rays irradiated by the infrared irradiation means and reflected on the chuck table 25, and outputs an electrical signal corresponding to the infrared rays. The image captured by the imaging means 7 is sent to the control means and displayed on an appropriate display means (not shown).

In FIG. 1, a laser processing device 2 is shown together with a wafer 10 prepared as a workpiece to be processed by this embodiment, and an annular frame F that holds the wafer 10 via a protective tape T with an adhesive layer. The wafer 10 is, for example, a silicon wafer with a thickness of 700 μm, and a number of devices are formed on the surface and partitioned by intended division lines.

Figure 2 shows a schematic cross-sectional view of the condenser 64 constituting the laser beam application means 6, as well as an optical system 60 that introduces a laser beam into the condenser 64, and an air supply system 8 that supplies air to the air supply unit 641 of the laser beam application means 6. Each component will be described below.

The laser beam application means 6 includes at least an oscillator 61 that oscillates a pulsed laser beam LB0 and a condenser 64. As can be seen from the condenser 64 shown in the cross-sectional view of FIG. 2, the condenser 64 includes a cylinder 640 that protrudes toward the workpiece side (downward in the figure) in the Z-axis direction (up and down direction) indicated by the arrow Z, and an air supply unit 641 that constitutes the lower side of the cylinder 640. A condenser lens 65 is held inside the cylinder 640, and a cover glass 66 that is surrounded and held by the cylinder 640 is disposed on the workpiece side of the condenser lens 65. Furthermore, the laser beam application means 6 of this embodiment includes an attenuator 62 that adjusts the laser beam LB0 to an appropriate output, and a reflecting mirror 63 that changes the optical path of the laser beam LB1 whose output has been adjusted by the attenuator 62. The laser beam LB1 reflected by the reflecting mirror 63 is focused by a focusing lens 65 arranged in the focusing device 64 and irradiated onto the workpiece positioned below the focusing device 64. The cover glass 66 protects the focusing lens 65 from debris that is scattered when the workpiece is laser-processed through the laser beam LB1. Inside the air supply unit 641 of the cylinder 640, in the space S1 through which the laser beam LB1 passes after passing through the cover glass 66, an air injection nozzle 80 is arranged to inject air diagonally from below toward the cover glass 66 and remove debris adhering to the cover glass 66.

The above-mentioned air injection nozzle 80 will be described in more detail with reference to Figs. 2 and 3. Fig. 3(a) shows a view from the end face 80a side of the air injection nozzle 80, Fig. 3(b) shows the A-A cross section cut at A-A in Fig. 3(a), and Fig. 3(c) shows the B-B cross section cut at B-B in Fig. 3(a). The A-A cross section shown in Fig. 3(b) is a vertical cross section cut along and perpendicular to the axis of the air injection nozzle 80, passing through the center of the end face 80a of the air injection nozzle 80, and the B-B cross section shown in Fig. 3(c) is a horizontal cross section cut along the axis from the tip of the air injection nozzle 80, passing through the center of the end face 80a of the air injection nozzle 80, while maintaining the horizontality.

As can be seen from Figures 3(a) to (c), a large-diameter main nozzle 81 is formed in the center of the end face 80a of the air injection nozzle 80, and four sub-nozzles, namely a first sub-nozzle 82, a second sub-nozzle 83, a third sub-nozzle 84, and a fourth sub-nozzle 85, are arranged around the main nozzle 81, have a smaller diameter than the main nozzle 81, and are evenly spaced in the circumferential direction. The main nozzle 81 is oriented toward the center of the cover glass 66, and the tip side of each sub-nozzle is inclined toward the axis C of the main nozzle 81 (= the axis of the air injection nozzle 80).

Returning to FIG. 2, the air supply system 8 that supplies air to the air injection nozzle 80 will be described. The air supply system 8 includes a high-pressure air supply source P1 that compresses and delivers 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 the first sub-nozzle 82, a third air flow path 93 that supplies air to the second sub-nozzle 83, a fourth air flow path 94 that supplies air to the third sub-nozzle 84, and a fifth air flow path 95 that supplies air to the fourth sub-nozzle 85.

A first opening/closing valve VL1 for opening and closing the first air flow path 91 is provided on the first air flow path 91, a second opening/closing valve VL2 for opening and closing the second air flow path 92 is provided on the second air flow path 92, a third opening/closing valve VL3 for opening and closing the third air flow path 93 is provided on the third air flow path 93, a fourth opening/closing valve VL4 for opening and closing the fourth air flow path 94 is provided on the fourth air flow path 94, and a fifth opening/closing valve VL5 for opening and closing the fifth air flow path 95 is provided on the fifth air flow path 95. A first buffer tank B1 is disposed between the second on-off valve VL2 and the first sub-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 sub-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 sub-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 sub-nozzle 85 on the fifth air flow path 95. Each buffer tank has the function of accumulating a portion of the high-pressure air supplied via each air flow path, and therefore functions to make the rise in the injection pressure of the high-pressure air sprayed from each sub-nozzle gradual when the supply of high-pressure air begins via each air flow path, and to gradually reduce the injection pressure of the high-pressure air sprayed from each sub-nozzle after the supply of high-pressure air from each air flow path is stopped. The first to fifth opening and closing valves VL1 to VL5 are normally closed valves that are closed in a steady state, and are controlled to open at a predetermined timing based on a command signal from a control program stored in the control means 100.

The air supply unit 641 disposed in the collector 64 of this embodiment also functions as a downflow generating section that generates a downflow that suppresses the intrusion of debris scattered by processing the wafer 10 into the cover glass 66. More specifically, as shown in FIG. 2, the air supply unit 641 of the collector 64 has an air flow path 642 for generating a downflow formed therein, and a sixth air flow path 96 for supplying high-pressure air from the high-pressure air supply source P2 is connected to the air flow path 642 for generating a downflow. A sixth opening/closing valve VL6 for opening and closing the sixth air flow path 96 is disposed on the sixth air flow path 96. The sixth opening/closing valve VL6 is a normally closed valve that is connected to the control means 100 and is controlled to open or close by a command signal issued from the control means 100. Inside the cylinder 640 that supports the cover glass 66, an annular flange 67 with an opening 68 formed in the center is formed below the cover glass 66, and an annular space S2 is formed between the cover glass 66 and the annular flange 67. The high-pressure air supplied through the sixth air flow path 96 passes through the downflow air flow path 642, is supplied from the side of the cover glass 66 to the above-mentioned annular space S2, and is discharged as a downflow that flows from the opening 68 into the lower space S1 where the air injection nozzle 80 is disposed.

Furthermore, the air supply unit 641 is formed with a suction flow path 643 and an outside air introduction path 644, one end of which opens into the space S1 below. The other end of the suction flow path 643 is connected to a suction source P3 that supplies negative pressure via a seventh air flow path 97, and a seventh opening/closing valve VL7 that opens and closes the seventh air flow path 97 is disposed on the seventh air flow path 97. The other end of the outside air introduction path 644 is opened to the outside to introduce outside air A. The seventh opening/closing valve VL7 is a normally closed valve that is connected to the control means 100 and is controlled to open by a command signal issued from the control means 100. One end of the suction flow path 643 forms a suction opening 643a in the shape of a circular arc that is long in the horizontal direction on the inner wall surface that forms the space S1 (not shown). In addition, one end of the outside air introduction passage 644 forms an outside air introduction opening 644a (not shown) that is long in the horizontal direction (horizontal direction) and has an arc-shaped shape similar to the above-mentioned suction opening 643a at a position facing the above-mentioned suction opening 643a on the inner wall surface that forms the space S1. When high-pressure air supplied through the sixth air flow path 96 forms a downflow that flows from the opening 68 into the lower space S1, the above-mentioned suction source P3 is operated and the seventh opening/closing valve VL7 is opened, so that debris 110 contained in the downflow that flows into the lower space S1 can be sucked in through the suction opening 643a without leaking to the outside.

The laser processing device 2 of this embodiment has a configuration generally as described above, and its functions and operations are described below.

First, we will explain the case where the air supply unit 641 of the laser beam application means 6 is operated to function as a downflow generating unit when performing laser processing to form a laser processed groove on the surface of the wafer 10 using the above-mentioned laser processing device 2.

First, the wafer 10 supported on the frame F via the protective tape T is placed on the chuck table 25 of the laser processing device 2 shown in FIG. 1 and held by suction. Next, the moving means 30 is operated to position the chuck table 25 below the imaging means 7, and the wafer 10 is imaged from above to perform alignment, and the processing position on the wafer 10 where the laser processing is performed (for example, the position of the planned dividing line that divides the device) is detected, and the position information of the processing position is recorded in the control means 100.

Based on the position information detected by the alignment, the moving means 30 is operated to position the condenser 64 of the laser beam application means 6 above the position on the wafer 10 where laser processing is performed, as shown in FIG. 4. Next, the sixth opening/closing valve VL6 and the seventh opening/closing valve VL7 are opened, and the high-pressure air supply source P2 and the suction source P3 are operated to generate a downflow F1 that flows toward the space S1 below the air supply unit 641, and below the space S1, a recovery flow F2 that flows from the outside air introduction opening 644a to the suction opening 643a is formed. Next, the condenser 64 is operated to position the focal point position of the laser beam LB1 on the surface 10a of the wafer 10, and the laser beam application means 6 is operated to irradiate the laser beam LB1 while the moving means 30 is operated as a feed means to feed the chuck table 25 in the direction indicated by the arrow X, forming a laser processing groove 11 on the surface 10a of the wafer 10.

The laser processing conditions for carrying out the above-mentioned laser processing are set, for example, as follows.
Wavelength: 355 nm
Repetition frequency: 50kHz
Average power output: 4W
Processing feed speed: 150 mm/sec

By carrying out the above-mentioned laser processing, a laser processing groove 11 is formed on the surface 10a of the wafer 10, and at this time, particulate debris 110 formed by melting silicon is generated and scattered upward. This debris 110 enters the inside of the collector 64, but as described above, since a downflow F1 is generated in the space S1 below the inside of the air supply unit 641, most of the debris 110 scattered upward is guided downward without reaching the cover glass 66, and is collected in the suction flow path 643 by the collection flow F2 flowing below the air supply unit 641. Although not shown, an air filter is provided in the seventh air flow path 97 connected to the suction flow path 643, and the sucked debris 110 is collected. In this way, by giving the air supply unit 641 of the collector 64 the function of a downflow generating section, the debris 110 scattered during laser processing is prevented from adhering to the cover glass 66, and the scattered debris 110 can be collected in the seventh air flow path 97. By performing laser processing on all of the predetermined processing positions on the wafer 10 while operating the moving means 30 that feeds the chuck table 25 for processing, the laser processing on the wafer 10 is completed while collecting the debris 110 scattered from the processing positions.

By carrying out the laser processing as described above, adhesion of debris 110 to the cover glass 66 can be suppressed to some extent, but even if the downflow F1 shown in FIG. 4 is generated, it is difficult to completely prevent contamination by debris 110. Therefore, after carrying out the above-described laser processing a predetermined number of times, a debris removal process is carried out at any time to remove debris 110 from the cover glass 66, as described below. The debris removal process will be described with reference to FIGS. 1, 2, and 5 to 7.

When performing the debris removal process, the moving means 30 is operated to move the chuck table 25 to a loading/unloading position (the position where the chuck table 25 is positioned in FIG. 1) where the wafer 10 is loaded and unloaded from the chuck table 25. Next, with the sixth opening/closing valve VL6 shown in FIG. 2 closed, the high-pressure air supply source P2 is stopped, the seventh opening/closing valve VL7 is opened, and the suction source P3 is operated. Next, the high-pressure air supply source P1 is operated and the first opening/closing valve VL1 is opened. As a result, as can be seen from FIG. 6 showing the A-A cross section of the end face 80a of the air injection nozzle 80, high-pressure air is supplied to the air injection nozzle 80 only through the first air flow path 91 of the air flow path 90, and high-pressure air 120A is injected only from the main nozzle 81. The ejected high-pressure air 120A travels straight along the axis C of the main nozzle 81 and is blown toward the approximate center of the cover glass 66 as shown in FIG. 5, causing the debris 110 attached to the central region of the cover glass 66 to separate and fall. The debris 110 separated from the central region of the cover glass 66 falls through the space S1 and is carried by the recovery flow F2 formed by the suction opening 643a and the outside air introduction opening 644a, is sucked in through the suction flow path 643, and is recovered via the seventh air flow path 97.

As described above, when the high-pressure air 120A is injected from the main nozzle 81 of the air injection nozzle 80 for a predetermined time, the first opening and closing valve VL1 is left open, i.e., the high-pressure air 120A moving straight from the main nozzle 81 is still being injected, and the second opening and closing valve VL2 is opened. As a result, as shown in FIG. 7(a) showing the A-A cross section of the end face 80a of the air injection nozzle 80, the high-pressure air is introduced into the second air flow path 92, and the high-pressure air is also injected from the first sub-nozzle 82. As described above, the first sub-nozzle 82 is inclined toward the axis C of the main nozzle 81, and the high-pressure air injected from the first sub-nozzle 82 is injected toward the high-pressure air 120A injected from the main nozzle 81, and as a result, the high-pressure air 120A injected from the main nozzle 81 becomes the high-pressure air 120B adjusted to follow the direction C1 injected from the first sub-nozzle 82. The direction in which the high-pressure air 120B is injected is toward the third sub-nozzle 84 as shown on the right side of FIG. 7(a), and the high-pressure air 120B is injected toward the area of the cover glass 66 in the direction away from the air injection nozzle 80 (to the right in FIG. 5). Incidentally, the first buffer tank B1 is disposed in the second air flow path 92 of this embodiment as described above. Therefore, by the action of the first buffer tank B1 described above, the injection pressure of the high-pressure air injected from the first sub-nozzle 82 gradually increases, and the direction of the high-pressure air 120A injected from the main nozzle 81 of the air injection nozzle 80 is adjusted so that it does not suddenly switch to the high-pressure air 120B but switches smoothly. Therefore, the high-pressure air is sufficiently blown to the intermediate area between the area of the cover glass 66 where the high-pressure air 120A was strongly blown and the area where the high-pressure air 120B was strongly blown, and the debris 110 attached to the cover glass 66 is well removed.

After the high-pressure air 120B is sprayed from the air injection nozzle 80 for a predetermined time, the second opening and closing valve VL2 is closed and the third opening and closing valve VL3 disposed in the third air flow path 93 is opened. This stops the supply of high-pressure air to the second air flow path 92, and as can be seen from FIG. 7(b) showing the B-B cross section of the end face 80a of the air injection nozzle 80, high-pressure air is introduced into the third air flow path 93 and sprayed from the second sub-nozzle 83. As a result, the high-pressure air 120B sprayed in the direction C1 shown in FIG. 7(a) becomes the high-pressure air 120C adjusted to follow the direction C2 along the direction sprayed from the second sub-nozzle 83, as shown in FIG. 7(b). The direction in which the high pressure air 120C is injected is from the second sub-nozzle 83 toward the fourth sub-nozzle 85 as shown on the right side of Fig. 7B, and the high pressure air 120C is injected toward a region directed toward the rear side in the Y-axis direction (perpendicular to the paper surface) of the cover glass 66 shown in Fig. 5. Incidentally, the second buffer tank B2 is also disposed in the third air flow path 93 of this embodiment as described above. Therefore, when the second opening/closing valve VL2 is closed and the third opening/closing valve VL3 disposed in the third air flow path 93 is opened at the same time, the first buffer tank B1 and the second buffer tank B2 described above act to gradually decrease the injection pressure of the high pressure air injected from the first sub-nozzle 82 and gradually increase the injection pressure of the high pressure air injected from the second sub-nozzle 83, so that the high pressure air 120B injected from the air injection nozzle 80 is adjusted to be smoothly switched to the high pressure air 120C without being abruptly switched to. Therefore, the high-pressure air is sufficiently blown to the intermediate area between the area on the cover glass 66 where the high-pressure air 120B is strongly blown and the area where the high-pressure air 120C is strongly blown, and the debris 110 adhering to the cover glass 66 in that area is effectively removed.

Furthermore, after the high pressure air 120C is injected from the air injection nozzle 80 for a predetermined time, the third opening and closing valve VL3 is closed and the fourth opening and closing valve VL4 disposed in the fourth air flow path 94 is opened at the same time. This stops the supply of high pressure air to the third air flow path 93, and as shown in FIG. 7(c) showing the A-A cross section of the end face 80a of the air injection nozzle 80, high pressure air is introduced into the fourth air flow path 94 and injected from the third sub-nozzle 84. As a result, the high pressure air 120C injected in the direction C2 shown in FIG. 7(b) becomes high pressure air 120D adjusted to follow the direction C3 along the direction injected from the third sub-nozzle 84, as shown in FIG. 7(c). The direction in which this high-pressure air 120D is sprayed is from the third sub-nozzle 84 toward the first sub-nozzle 82 as shown on the right side of Fig. 7(c), and this high-pressure air 120D is sprayed to the area on the side where the air injection nozzle 80 in the X-axis direction is arranged (to the left in the figure) of the cover glass 66 shown in Fig. 5. Incidentally, the third buffer tank B3 is also arranged in the fourth air flow path 94 of this embodiment, as described above. Therefore, when the third opening/closing valve VL3 is closed and the fourth opening/closing valve VL4 disposed in the fourth air flow path 94 is opened at the same time, the second buffer tank B2 and the third buffer tank B3 described above act to gradually lower the injection pressure of the high-pressure air injected from the second sub-nozzle 83 and gradually increase the injection pressure of the high-pressure air injected from the third sub-nozzle 84, so that the high-pressure air 120C injected from the air injection nozzle 80 is adjusted so as to smoothly switch to the high-pressure air 120D without suddenly switching to the high-pressure air 120D. Therefore, the high-pressure air is sufficiently blown to the intermediate region of the cover glass 66 between the region where the high-pressure air 120C was strongly blown and the region where the high-pressure air 120D was strongly blown, and the debris 110 attached to the cover glass 66 in that region is effectively removed.

After the high pressure air 120D is sprayed from the air injection nozzle 80 for a predetermined time, the fourth opening and closing valve VL4 is closed and the fifth opening and closing valve VL5 disposed in the fifth air flow path 95 is opened. This stops the supply of high pressure air to the fourth air flow path 94, and as shown in FIG. 7(d) showing the B-B cross section of the end face 80a of the air injection nozzle 80, the high pressure air is introduced into the fifth air flow path 95 and sprayed from the fourth sub-nozzle 85. As a result, the high pressure air 120D sprayed in the direction C3 shown in FIG. 7(c) becomes the high pressure air 120E adjusted to follow the direction C4 along the direction sprayed from the fourth sub-nozzle 85, as shown in FIG. 7(d). The direction in which the high pressure air 120E is ejected is from the fourth sub-nozzle 85 toward the second sub-nozzle 83 as shown on the right side of Fig. 7(d), and the high pressure air 120E is ejected toward the area of the cover glass 66 shown in Fig. 5 that faces the front side of the paper on which Fig. 5 is drawn. Incidentally, the fourth buffer tank B4 is also disposed in the fifth air flow path 95 of this embodiment as described above. Therefore, when the fourth opening/closing valve VL4 is closed and the fifth opening/closing valve VL5 disposed in the fifth air flow path 95 is opened at the same time, the third buffer tank B3 and the fourth buffer tank B4 act to gradually lower the ejection pressure of the high pressure air ejected from the third sub-nozzle 84 and gradually increase the ejection pressure of the high pressure air ejected from the fourth sub-nozzle 85, so that the high pressure air 120D ejected from the air ejection nozzle 80 is adjusted to be smoothly switched to the high pressure air 120E without being abruptly switched to. Therefore, the high-pressure air is sufficiently blown to the intermediate area between the area on the cover glass 66 where the high-pressure air 120D is strongly blown and the area where the high-pressure air 120E is strongly blown, and the debris 110 adhering to the cover glass 66 in that area is effectively removed.

As a result, the direction of the high-pressure air sprayed from the air spray nozzle 80 changes from C to C1 to C2 to C3 to C4, and is sprayed sequentially to the desired area of the cover glass 66, resulting in spraying evenly over the entire area of the cover glass 66. This makes it possible to effectively remove debris 110 that has adhered to the cover glass 66. In addition, since a buffer tank is provided in each of the air flow paths 90 that supply high-pressure air to each sub-nozzle, the direction of the high-pressure air sprayed from the air spray nozzle 80 changes smoothly, and sufficient high-pressure air is sprayed even in the intermediate area between where the direction of the high-pressure air sprayed from the air spray nozzle 80 changes from C to C1 to C2 to C3 to C4, eliminating the problem of debris 110 remaining on the surface of the cover glass 66.

In the above embodiment, four sub-nozzles are arranged at equal intervals around the outer periphery of the main nozzle 81 formed in the air injection nozzle 80, but the present invention is not limited to this, and the number of sub-nozzles can be set as desired. However, in order to inject high-pressure air onto the entire area of the cover glass 66, it is preferable to arrange three or more sub-nozzles surrounding the main nozzle 81.

In addition, in the above embodiment, the direction of the high-pressure air injected from the air injection nozzle 80 is changed from C to C1 to C2 to C3 to C4, and the air is injected sequentially onto the desired area of the cover glass 66. However, this operation can be repeated multiple times to further reduce the amount of debris 110 remaining on the cover glass 66.

In addition, in the above embodiment, the high-pressure air supply source P1 and the high-pressure air supply source P2 are provided separately, but the present invention is not limited to this, and one high-pressure air supply source P1 can also be shared.

2: Laser processing device 3: Base 4: Holding means 6: Laser beam application means 60: Optical system 61: Oscillator 62: Attenuator 63: Reflecting mirror 64: Condenser 640: Cylinder 641: Air supply unit 642: Downflow air flow path 643: Suction flow path 643a: Suction opening 644: Outside air introduction path 644a: Outside air introduction opening 65: Condenser lens 66: Cover glass 67: Annular flange 68: Opening 8: Air supply system 80: Air injection nozzle 80a: Nozzle end surface 81: Main nozzle 82: First sub-nozzle 83: Second sub-nozzle 84: Third sub-nozzle 85: Fourth sub-nozzle 10: Wafer 11: Laser processing groove 21: X-axis direction movable plate 22: Y-axis direction movable plate 25: Chuck table 30: Moving means 31: X-axis direction feed means 32: Y Axial feed means 37: Frame 37a: Vertical wall portion 37b: Horizontal wall portion 80: Air injection nozzle 80a: End surface 90: Air flow path 91: First air flow path 92: Second air flow path 93: Third air flow path 94: Fourth air flow path 95: Fifth air flow path 96: Sixth air flow path 97: Seventh air flow path 110: Debris 120A to 120E: High pressure air B1: First buffer tank B2: Second buffer tank B3: Third buffer tank B4: Fourth buffer tank F1: Down flow F2: Recovery flow VL1: First opening and closing valve VL2: Second opening and closing valve VL3: Third opening and closing valve VL4: Fourth opening and closing valve VL5: Fifth opening and closing valve VL6: Sixth opening and closing valve S1, S2: Space LB0, LB1: Laser beam P1, P2: High pressure air supply source P3: Suction source

Claims (3)

A laser processing apparatus comprising at least a holding means for holding a workpiece, a laser beam application means for applying a laser beam to the workpiece held by the holding means, and a feed means for relatively feeding the holding means and the laser beam application means for processing,
the laser beam application means includes an oscillator that oscillates a laser beam and a condenser that condenses the laser beam oscillated by the oscillator;
The condenser includes a condenser lens, a cover glass that protects the condenser lens from debris that scatters when a workpiece is laser-processed, and an air injection nozzle that injects air toward the cover glass to remove the debris;
The air injection nozzle includes a main nozzle and a sub-nozzle, the main nozzle injects air toward the cover glass, and the sub-nozzle injects air toward the air injected from the main nozzle, thereby adjusting the injection direction of the air injected from the main nozzle. The laser processing device according to claim 1, wherein the condenser includes a cylinder that surrounds the cover glass and protrudes toward the workpiece, and a downflow generating unit that supplies air to the inside of the cylinder during laser processing to generate a downflow that prevents debris from entering the inside of the cylinder. The laser processing device according to claim 1 or 2, in which a buffer tank is disposed in the air flow path that supplies air to the sub-nozzle, and the direction of the air sprayed from the main nozzle is smoothly changed.