JP7450447B2 - laser processing equipment - Google Patents

Description

The present invention relates to a laser processing device.

In order to process workpieces such as semiconductor wafers, there is a method of irradiating the workpiece with a laser beam of an absorbing wavelength to form processing grooves and making chips, and a method that is transparent to the workpiece. A method has been proposed in which the workpiece is divided by condensing and irradiating a laser beam having a wavelength of 100 nm into the interior of the workpiece to form a modified layer that serves as a starting point for division (see Patent Document 1 and Patent Document 2).

In the laser processing apparatus that performs the laser processing described above, if the output of the laser beam changes, there is a risk that the workpiece may be divided incorrectly. For this reason, it is extremely important to confirm that the set output of the laser beam is the same as the actual output. Therefore, a method of measuring the output of a laser beam using a power meter has been proposed (see, for example, Patent Document 3).

However, in the power meter shown in Patent Document 3, which is generally used to measure the output of a laser beam, the light-receiving surface is heated by the received laser beam, and the heat on the light-receiving surface is converted into an electrical signal to measure the output. It takes about 4 seconds from the start of the measurement for the output of the laser beam, which is the measurement result, to reach a constant value. Furthermore, in order to measure the output of the laser beam, the power meter described above needs to either block the optical path by itself or interrupt processing and irradiate the power meter with the laser beam. For this reason, the power meter disclosed in Patent Document 3 and the like has a problem in that the number of wafers processed per unit time, that is, productivity decreases by repeating the above-mentioned measurement.

Therefore, a method has been proposed in which the output of a laser beam is monitored without interrupting processing by using light transmitted through a mirror (see Patent Document 4).

Japanese Patent Application Publication No. 2003-320466 Patent No. 3408805 JP2009-291818A Patent application No. 2019-155067

By using the method shown in Patent Document 4, it is possible to measure the output while processing the workpiece. However, when using the method shown in Patent Document 4, the laser beam actually used for processing is the one that has passed through the condensing lens, and the laser beam whose output is measured is the one that has not passed through the condensing lens. Therefore, if a problem occurs such as dirt adhering to the condenser lens, there still remains the problem that the output of the laser beam actually irradiated onto the workpiece cannot be accurately measured.

The present invention has been made in view of the above facts, and its purpose is to provide a laser processing device that can accurately measure the output of a laser beam after passing through a condenser lens without reducing productivity. It is.

In order to solve the above-mentioned problems and achieve the objectives, the laser processing apparatus of the present invention includes a chuck table that holds a workpiece, and a pulsed laser beam that irradiates the workpiece held on the chuck table. a processing feed unit that relatively processes and feeds the chuck table and the laser beam irradiation unit; and an indexing feed unit that relatively indexes and feeds the chuck table and the laser beam irradiation unit. , an output measurement unit disposed adjacent to the chuck table and measuring the output of the laser beam, and a control unit controlling each component; the laser beam irradiation unit includes a laser oscillator; a condensing lens that condenses a laser beam oscillated from the laser oscillator and irradiates it onto the workpiece, and the output measurement unit is positioned at a position where the laser beam after passing through the condensing lens can be measured. The control unit includes a storage unit that stores, as data, a time since the output measurement unit was irradiated with the laser beam and a change in output due to a change in the time; a prediction unit that predicts the output of the laser beam at a stable time when the output does not change based on the data, based on the output of the laser beam for a time shorter than the time required for the output to become stable; and a prediction unit that processes the workpiece. a movement control section that controls a moving distance of the processing feed unit so that the laser beam passes through the workpiece held on the chuck table and the light receiving section of the output measurement unit; It is characterized by having the following.

The laser processing apparatus of the present invention includes a chuck table that holds a workpiece, a laser beam irradiation unit that irradiates the workpiece held on the chuck table with a pulsed laser beam, and the chuck table and the laser beam. a processing feed unit that processes and feeds the irradiation unit relatively; an indexing feed unit that relatively indexes and feeds the chuck table and the laser beam irradiation unit; The laser beam irradiation unit includes an output measurement unit that measures the output of the laser beam, and a control unit that controls each component, and the laser beam irradiation unit includes a laser oscillator and a laser beam emitted from the laser oscillator. a condenser lens that irradiates the workpiece, the output measurement unit is disposed at a position where it can measure the laser beam after passing through the condenser lens, and includes a light receiving section that directly receives the laser beam. a power meter equipped with the laser beam; and a photodiode equipped with a light receiving section that receives scattered light of the laser beam; a storage unit that stores correlation data between the output of the laser beam of the scattered light measured in the storage unit; and an equilibrium of the actual laser beam from the output of the laser beam of the scattered light based on the correlation data stored in the storage unit. a prediction unit that calculates the output; when processing the workpiece, the laser beam passes through the workpiece held on the chuck table; and a light receiving unit of the output measurement unit; The apparatus is characterized by comprising a movement control section that controls a movement distance of the processing and feeding unit .

The present invention has the effect that the output of a laser beam after passing through a condenser lens can be accurately measured without reducing productivity.

FIG. 1 is a perspective view showing a configuration example of a laser processing apparatus according to a first embodiment. FIG. 2 is an explanatory diagram illustrating a schematic configuration of a laser beam irradiation unit of the laser processing apparatus shown in FIG. 1. FIG. FIG. 3 is a diagram showing an example of a laser beam output indicated by an electric signal output by the laser beam irradiation unit shown in FIG. 2. FIG. FIG. 4 is a plan view schematically showing the irradiation position of the laser beam of the laser beam irradiation unit on the workpiece of the laser processing apparatus shown in FIG. FIG. 5 is a side view schematically showing a laser beam irradiated by the laser beam irradiation unit shown in FIG. 4 and a workpiece. FIG. 6 is a perspective view showing an output measurement unit of the laser processing apparatus according to the second embodiment. FIG. 7 is a diagram showing data stored in the storage section of the control unit of the laser processing apparatus according to the second embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Modes (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. Further, 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 configurations described below can be combined as appropriate. Further, various omissions, substitutions, or changes in the configuration can be made without departing from the gist of the present invention.

[Embodiment 1]
DESCRIPTION OF THE PREFERRED EMBODIMENTS A laser processing apparatus according to a first embodiment of the present invention will be described based on the drawings. First, the configuration of the laser processing apparatus 1 according to the first embodiment will be explained. FIG. 1 is a perspective view showing a configuration example of a laser processing apparatus according to a first embodiment. The laser processing apparatus 1 shown in FIG. 1 according to the first embodiment is an apparatus that irradiates the workpiece 200 with a pulsed laser beam 21 and processes the workpiece 200 with the laser beam.

(Workpiece)
A workpiece 200 to be processed by the laser processing apparatus 1 shown in FIG. 1 is a wafer such as a disk-shaped semiconductor wafer or an optical device wafer, which has a substrate 201 made of silicon, sapphire, gallium arsenide, or the like. As shown in FIG. 1, the workpiece 200 has dividing lines 203 set in a grid pattern on the surface 202 of the substrate 201, and devices 204 formed in areas partitioned by the dividing lines 203. are doing. The device 204 is, for example, an integrated circuit such as an IC (Integrated Circuit) or an LSI (Large Scale Integration), an image sensor such as a CCD (Charge Coupled Device), or a CMOS (Complementary Metal Oxide Semiconductor).

In the first embodiment, the workpiece 200 has a disk shape with a larger diameter than the outer diameter of the workpiece 200, and an adhesive tape 208 with an annular frame 210 attached to the outer edge is attached to the back surface 205 on the back side of the front surface 202. and is supported within the opening 207 of the annular frame 210. In the first embodiment, the workpiece 200 is divided into individual devices 204 along a planned dividing line 203 .

As shown in FIG. 1, the laser processing apparatus 1 includes a chuck table 10 that holds a workpiece 200 on a holding surface 11, a laser beam irradiation unit 20, a movement unit 30, an imaging unit 40, and an output measurement unit 50. and a control unit 100.

The chuck table 10 holds a workpiece 200 with a holding surface 11 . The holding surface 11 has a disc shape made of porous ceramic or the like, and is connected to a vacuum suction source (not shown) via a vacuum suction path (not shown). The chuck table 10 holds the workpiece 200 placed on the holding surface 11 by suction. In the first embodiment, the holding surface 11 is a plane parallel to the horizontal direction. A plurality of clamp parts 12 are arranged around the chuck table 10 to clamp an annular frame 210 that supports the workpiece 200 in the opening 207.

Furthermore, the chuck table 10 is rotated by the rotary movement unit 34 of the movement unit 30 around an axis that is perpendicular to the holding surface 11 and parallel to the Z-axis direction that is parallel to the vertical direction. The chuck table 10 is moved along with the rotational movement unit 34 in the X-axis direction parallel to the horizontal direction by the X-axis movement unit 31 of the movement unit 30, and is moved in the X-axis direction parallel to the horizontal direction and perpendicular to the X-axis direction by the Y-axis movement unit 32. is moved in the Y-axis direction.

The laser beam irradiation unit 20 is a unit that irradiates the workpiece 200 held on the chuck table 10 with a pulsed laser beam 21 . In the first embodiment, the laser beam irradiation unit 20 irradiates the workpiece 200 with a pulsed laser beam 21 having a transmittable wavelength to form a modified layer that becomes a fracture starting point inside the workpiece 200. It is a laser beam irradiation means that forms a. A modified layer refers to a region whose density, refractive index, mechanical strength, and other physical properties are different from those of its surroundings. The modified layer includes, for example, a melt-treated region, a crack region, a dielectric breakdown region, a refractive index change region, and a region in which these regions are mixed. In embodiments, the modified layer has lower mechanical strength than other parts of the substrate 201.

Note that in the first embodiment, the laser beam irradiation unit 20 irradiates the workpiece 200 with the laser beam 21 having a transmitting wavelength, but in the present invention, the laser beam 21 having a wavelength having an absorbing property is The workpiece 200 may be subjected to ablation processing by irradiation. In the first embodiment, as shown in FIG. 1, a part of the laser beam irradiation unit 20 is moved in the Z-axis direction by a Z-axis moving unit 33 of a moving unit 30 provided on an erected wall 3 erected from the apparatus main body 2. It is supported by an elevating member 4 that is moved.

Next, the configuration of the laser beam irradiation unit 20 will be explained. FIG. 2 is an explanatory diagram illustrating a schematic configuration of a laser beam irradiation unit of the laser processing apparatus shown in FIG. 1. FIG. FIG. 3 is a diagram showing an example of a laser beam output indicated by an electric signal output by the laser beam irradiation unit shown in FIG. 2. FIG.

As shown in FIG. 2, the laser beam irradiation unit 20 includes a laser oscillator 22 that oscillates a pulsed laser beam 21 for processing a workpiece 200, and a laser beam 21 that focuses the laser beam 21 oscillated from the laser oscillator 22. A condenser lens 23 is provided on the optical path of the laser beam 21 between the laser oscillator 22 and the condenser lens 23 and irradiates the workpiece 200 held on the holding surface 11 of the chuck table 10. includes an attenuator (also referred to as an attenuator) 24 that attenuates the laser beam 21 oscillated by the attenuator 24 , and a mirror 25 that reflects the laser beam 21 attenuated by the attenuator 24 toward the condenser lens 23 .

The condensing lens 23 is arranged at a position facing the holding surface 11 of the chuck table 10 in the Z-axis direction, and transmits the laser beam 21 oscillated from the laser oscillator 22 to condense the laser beam 21 at a condensing point 211. Let it shine.

The attenuator 24 includes a hollow motor 26, a λ/2 wavelength plate 27, a beam splitter 28, and a beam damper 29, as shown in FIG. The hollow motor 26 is formed in an annular shape, and allows the laser beam 21 oscillated by the laser oscillator 22 to pass through the hollow motor 26 . The λ/2 wavelength plate 27 is rotated by the hollow motor 26 around the optical axis of the laser beam 21 oscillated by the laser oscillator 22 . The λ/2 wavelength plate 27 gives a phase difference of λ/2 (180°) and emits the laser beam 21.

The beam splitter 28 reflects the S-polarized laser beam 21 of the laser beam 21 that has passed through the λ/2 wavelength plate 27 toward the beam damper 29, and transmits the P-polarized laser beam 21 toward the mirror 25. The beam damper 29 terminates the S-polarized laser beam 21 reflected by the beam splitter 28.

The moving unit 30 relatively moves the laser beam irradiation unit 20 and the chuck table 10 in the X-axis direction, the Y-axis direction, the Z-axis direction, and around an axis parallel to the Z-axis direction. The X-axis direction and the Y-axis direction are directions parallel to the holding surface 11. The moving unit 30 includes an X-axis moving unit 31 that is a processing feed unit that moves the chuck table 10 in the X-axis direction, a Y-axis moving unit 32 that is an indexing feed unit that moves the chuck table 10 in the Y-axis direction, and a laser. It includes a Z-axis moving unit 33 that moves the condensing lens 23 included in the beam irradiation unit 20 in the Z-axis direction, and a rotational moving unit 34 that rotates the chuck table 10 around an axis parallel to the Z-axis direction.

The Y-axis moving unit 32 is a unit that relatively indexes and feeds the chuck table 10 and the laser beam irradiation unit 20. In the first embodiment, the Y-axis moving unit 32 is installed on the device main body 2 of the laser processing device 1. The Y-axis moving unit 32 supports the moving plate 15, which supports the X-axis moving unit 31, so as to be movable in the Y-axis direction.

The X-axis moving unit 31 is a unit that relatively processes and feeds the chuck table 10 and the laser beam irradiation unit 20. The X-axis moving unit 31 is installed on the moving plate 15. The X-axis moving unit 31 supports the second moving plate 16, which supports a rotational moving unit 34 that rotates the chuck table 10 around an axis parallel to the Z-axis direction, so as to be movable in the X-axis direction. The Z-axis moving unit 33 is installed on the standing wall 3 and supports the elevating member 4 so as to be movable in the Z-axis direction.

The X-axis moving unit 31, the Y-axis moving unit 32, and the Z-axis moving unit 33 are a known ball screw rotatably provided around the axis, a known pulse motor that rotates the ball screw around the axis, and a moving plate. 15 and 16 so as to be movable in the X-axis direction or the Y-axis direction, and a well-known guide rail that supports the elevating member 4 so as to be movable in the Z-axis direction.

The laser processing apparatus 1 also includes an X-axis position detection unit (not shown) for detecting the position of the chuck table 10 in the X-axis direction, and a Y-axis direction position detection unit (not shown) for detecting the position of the chuck table 10 in the Y-axis direction. It includes a position detection unit and a Z-axis position detection unit that detects the position of the condenser lens 23 included in the laser beam irradiation unit 20 in the Z-axis direction. Each position detection unit outputs a detection result to the control unit 100.

The imaging unit 40 takes an image of the workpiece 200 held on the chuck table 10. The imaging unit 40 includes an imaging device such as a CCD (Charge Coupled Device) imaging device or a CMOS (Complementary MOS) imaging device that images the workpiece 200 held on the chuck table 10 . In the first embodiment, the imaging unit 40 is attached to the tip of the housing of the laser beam irradiation unit 20 and is arranged in a position aligned with the condensing lens 23 shown in FIG. 2 of the laser beam irradiation unit 20 in the X-axis direction. There is. The imaging unit 40 images the workpiece 200 to obtain an image for performing alignment for positioning the workpiece 200 and the laser beam irradiation unit 20, and outputs the obtained image to the control unit 100. do.

The output measurement unit 50 is a unit that measures the output of the laser beam 21. The output measurement unit 50 includes a light receiving section 51 that receives the laser beam 21 emitted from the laser oscillator 22 and propagated by the attenuator 24, the mirror 25, the condensing lens 23, and the like. The light receiving unit 51 is disposed at a predetermined distance in the Z-axis direction from a condensing point 211 set inside the workpiece 200 held on the chuck table 10. In the first embodiment, the light receiving section 51 is arranged a predetermined distance below the light converging point 211.

The output measurement unit 50 is a power meter whose light receiving section 51 is heated by the laser beam 21 and converts the heat of the light receiving section 51 into an electrical signal. The output measurement unit 50 outputs the converted electrical signal to the control unit 100. In the first embodiment, the electrical signal output by the output measurement unit 50 is an electrical signal corresponding to the output of the laser beam 21 received by the light receiving section 51. In this way, the output measurement unit 50 measures the output of the laser beam 21 by outputting the above-described electrical signal to the control unit 100.

Further, in the first embodiment, the output measurement unit 50 is installed on the second moving plate 16 with the light receiving section 51 facing upward. In the first embodiment, the output measurement unit 50 is installed on the second moving plate 16 with the light receiving section 51 facing upward, so that the output measurement unit 50 is placed at a position where the laser beam 21 after passing through the condenser lens 23 can be measured. has been done. Further, in the first embodiment, the output measurement unit 50 is arranged at a position where the light receiving section 51 is lined up in the X-axis direction with at least one planned division line 203 of the workpiece 200 held on the holding surface 11. Thus, in the present invention, the fact that the light receiving section 51 is arranged in a position aligned in the X-axis direction with at least one scheduled dividing line 203 of the workpiece 200 held on the holding surface 11 means that the output measurement unit 50 is It is shown that it is disposed adjacent to the chuck table 10.

The control unit 100 controls each of the above-described components of the laser processing apparatus 1 to cause the laser processing apparatus 1 to perform a processing operation on the workpiece 200. Note that the control unit 100 includes an arithmetic processing device having a microprocessor such as a CPU (central processing unit), a storage device having a memory such as a ROM (read only memory) or a RAM (random access memory), and an input/output unit. A computer having an interface device. The arithmetic processing device of the control unit 100 performs arithmetic processing according to a computer program stored in a storage device, and sends a control signal for controlling the laser processing device 1 to the laser processing device 1 via an input/output interface device. The functions of the control unit 100 are realized by outputting to the above-mentioned components.

Further, the control unit 100 is connected to a display unit 110 configured with a liquid crystal display device that displays the status of machining operations, images, etc., and an input unit (not shown) used by an operator to register machining content information and the like. ing. The input unit includes at least one of a touch panel provided on the display unit 110 and an external input device such as a keyboard.

The control unit 100 converts the electrical signal from the power measurement unit 50 into the power of the laser beam 21 . The output of the laser beam 21 that is converted by the control unit 100 is determined by the output measuring unit 50 when the light receiving section 51 is heated by the laser beam 21 and the heat is converted into electricity according to the output of the laser beam 21, as shown by the dotted line in FIG. Since it is a so-called power meter that converts it into a signal, the light receiving section 51 starts receiving the laser beam 21 by the time it reaches the balanced output 52 (the stable output where the output does not change and the output does not increase any further). After that, it takes a predetermined time 53 (equivalent to the time required for the output to stabilize). This balanced output 52 is the output of the laser beam 21 of the laser beam irradiation unit 20 that the output measurement unit 50 wants to measure. The horizontal axis in FIG. 3 is the elapsed time since the light receiving unit 51 started receiving the laser beam 21, and the vertical axis in FIG. 3 is the output of the laser beam 21 converted by the control unit 100. be.

Further, the control unit 100 includes a storage section 101 and a prediction section 102, as shown in FIG. The storage unit 101 stores the elapsed time since the light receiving unit 51 of the output measurement unit 50 received the laser beam 21, and the output of the laser beam 21 after converting the electrical signal from the output measurement unit 50 according to a change in the elapsed time. The changes in and are stored as data 104. That is, the storage unit 101 stores data 104 similar to data that a so-called predictive thermometer predicts the body temperature before reaching the equilibrium temperature. For example, the data 104 is a mathematical formula for predicting the balanced output 52 from the pre-balanced output 55 of the laser beam 21 converted from the electrical signal from the output measuring unit 50 at the predicted time 54 (shown in FIG. 3). Note that the predicted time 54 is shorter than the predetermined time 53, and the pre-equilibrium output 55 is lower than the equilibrium output 52.

The prediction unit 102 predicts the equilibrium output 52 at which the output of the laser beam 21 will not change from the pre-equilibrium output 55 that is the irradiation of the laser beam 21 for a predicted time 54 shorter than the predetermined time 53 necessary for the output to become stable. It is something. Specifically, the prediction unit 102 refers to the data 104 stored in the storage unit 101 from the pre-equilibrium output 55 of the laser beam 21 obtained by converting the electrical signal from the output measurement unit 50 at the prediction time 54, and calculates the result as shown in FIG. 3, the balanced output 52 is predicted, as shown by the solid line. In this way, the prediction unit 102 of the control unit 100 predicts the balanced output 52 before reaching the balanced output 52.

Furthermore, the control unit 100 further includes a movement control section 103. When processing the workpiece 200 by irradiating the laser beam 21 onto each scheduled division line 203, the movement control unit 103 controls the laser beam 21 to touch the workpiece 200 held on the chuck table 10 and the output measurement. This is to control the moving distance of the chuck table 10 in the X direction by the X-axis moving unit 31 so as to pass through the light receiving section 51 of the unit 50. Specifically, based on the machining content information, the movement control unit 103 aligns the light receiving unit 51 of the output measurement unit 50 with the light receiving unit 51 of the output measurement unit 50 in the X-axis direction among the scheduled dividing lines 203 of the workpiece 200 held on the chuck table 10. A planned dividing line 203 is calculated.

If there is only one dividing line 203 of the workpiece 200 held on the chuck table 10 that is lined up with the light receiving section 51 of the output measuring unit 50 in the X-axis direction, the movement control unit 103 controls When irradiating the laser beam 21 onto this one planned dividing line 203, the moving unit 30 is controlled so that the laser beam 21 is directed from the outer edge of the workpiece 200 to above the light receiving section 51 of the output measuring unit 50. The control unit 100 temporarily stops irradiation of the laser beam 21 when the laser beam irradiation unit 20 moves from the outer edge of the workpiece 200 to above the light receiving section 51 of the output measurement unit 50, and irradiates the laser beam 21 on the light receiving section 51. Resume irradiation.

The movement control unit 103 controls the movement unit 30 so that the division line 203 to be processed next is located below the laser beam irradiation unit 20 with the laser beam irradiation unit 20 positioned above the light receiving unit 51. After relatively moving the laser beam irradiation unit 20 and the chuck table 10 in the Y-axis direction, the moving unit 30 is moved so that the laser beam irradiation unit 20 is directed above the dividing line 203 to be processed next. Control. When the laser beam irradiation unit 20 retreats from above the light receiving section 51, the control unit 100 stops irradiation of the laser beam 21 from the laser beam irradiation unit 20. In the present invention, even if the laser beam irradiation unit 20 is retracted from above the light receiving section 51, the laser beam 21 may continue to be irradiated if the output is weak.

In addition, the movement control unit 103 controls when there are a plurality of scheduled dividing lines 203 of the workpiece 200 held on the chuck table 10 that are lined up in the X-axis direction with the light receiving section 51 of the output measurement unit 50. , calculates the planned division line 203 closest to the center of the light receiving section 51 in the Y-axis direction, and controls each component as described above when irradiating the laser beam 21 to the nearest planned division line 203. In this way, in the embodiment, when the laser beam 21 is irradiated to one of the planned dividing lines 203 of the workpiece 200, even if the laser beam 21 passes over the planned dividing line 203, , the chuck table 10 and the laser beam irradiation unit 20 are moved relatively in the X-axis direction, which is the processing feed direction, and the laser beam 21 is irradiated onto the light receiving section 51 . Further, in the first embodiment, the movement control unit 103 relatively moves the chuck table 10 and the laser beam irradiation unit 20 in the Y-axis direction, which is the indexing and feeding direction, while the light receiving unit 51 is irradiated with the laser beam 21. let

Note that the functions of the storage unit 101 are realized by the storage device described above. The functions of the prediction unit 102 and the movement control unit 103 are realized by the arithmetic processing unit performing arithmetic processing according to a computer program stored in a storage device.

Next, the processing operation of the laser processing apparatus 1 described above will be explained. FIG. 4 is a plan view schematically showing the irradiation position of the laser beam of the laser beam irradiation unit on the workpiece of the laser processing apparatus shown in FIG. FIG. 5 is a side view schematically showing a laser beam irradiated by the laser beam irradiation unit shown in FIG. 4 and a workpiece. Note that the scheduled dividing line 203 is omitted in FIG. 4 .

In the laser processing apparatus 1 described above, the operator registers processing content information in the control unit 100, places the workpiece 200 on the holding surface 11 of the chuck table 10 via the adhesive tape 208, and the control unit 100 registers processing content information in the control unit 100. When an operator's instruction to start a machining operation is received, the machining operation is started based on the registered machining content information.

In the processing operation, the laser processing device 1 suction-holds the workpiece 200 to the holding surface 11 of the chuck table 10 via the adhesive tape 208, and clamps the annular frame 210 with the clamp section 12. Next, the moving unit 30 moves the chuck table 10 downward to the imaging unit 40, and the imaging unit 40 photographs the workpiece 200. The laser processing apparatus 1 performs alignment based on the image captured by the imaging unit 40.

The laser processing apparatus 1 causes the movement unit 30 to move the laser beam irradiation unit 20 and the workpiece 200 relatively along the dividing line 203 based on the processing content information, and separates the laser beam irradiation unit 20 from the workpiece 200. A pulsed laser beam 21 is irradiated onto the planned dividing line 203. In the first embodiment, as shown in FIG. 2, the laser processing apparatus 1 sets the focal point 211 of the laser beam 21 inside the substrate 201 of the workpiece 200, and directs the laser beam 21 onto the dividing line 203. The irradiation is performed to form a modified layer inside the substrate 201 along the planned dividing line 203 . After forming the modified layer inside the substrate 201 along all the scheduled dividing lines 203, the laser processing apparatus 1 stops irradiating the laser beam 21 and ends the processing operation.

In the processing operation, the laser processing device 1 moves the laser beam irradiation unit 20 in the X-axis direction relative to the chuck table 10 above each dividing line 203 while maintaining the position of the condensing point 211 in the Z-axis direction. , and is moved relative to the chuck table 10 along the Y-axis direction at a position a predetermined distance on the outer circumferential side from the end of each scheduled dividing line 203 . In the processing operation, the laser processing apparatus 1 irradiates the laser beam 21 at a position indicated by a solid line 300 in FIG. 4, where the laser beam irradiation unit 20 moves above the workpiece 200 relative to the chuck table 10. The irradiation of the laser beam 21 is stopped at a position indicated by a dotted line 301 in FIG. 4, which is moved a predetermined distance above the outer periphery of the workpiece 200 relative to the chuck table 10.

In addition, in the processing operation, the laser processing device 1 is closest to the planned dividing line 203 aligned in the X-axis direction with the light receiving section 51 of the output measurement unit 50 calculated by the movement control section 103 or the center of the light receiving section 51 in the Y-axis direction. When irradiating the laser beam 21 on the planned division line 203, the laser beam irradiation unit 20 is moved along the X-axis direction to above the light receiving section 51 of the output measurement unit 50, as shown in the solid line 300 in FIG. 4 and in FIG. While relatively moving, the laser beam 21 is irradiated from the laser beam irradiation unit 20 above the light receiving section 51 of the output measuring unit 50, and the laser beam is irradiated at a position above the center of the light receiving section 51 of the output measuring unit 50. The unit 20 is relatively moved along the Y-axis direction. Note that in the present invention, it is desirable to temporarily stop the relative movement of the laser beam irradiation unit 20 with respect to the light receiving part 51 above the light receiving part 51; You can also measure it.

In the laser processing apparatus 1, the light receiving section 51 of the output measuring unit 50 receives the laser beam 21, and outputs an electric signal according to the output of the laser beam 21 to the control unit 100. In the first embodiment, the light receiving section 51 of the output measurement unit 50 is placed a predetermined distance below the condensing point 211, so it receives the laser beam 21 that has diverged beyond the condensing point 211. .

The prediction unit 102 of the control unit 100 of the laser processing device 1 converts the electrical signal from the light receiving unit 51 at the predicted time 54 after the light receiving unit 51 starts receiving light into the pre-balanced output 55 of the laser beam 21. The balanced output 52 is predicted from the pre-balanced output 55 of the laser beam 21 by referring to the data 104 stored in the storage unit 101, as shown by the solid line in FIG.

As described above, in the laser processing apparatus 1 according to the first embodiment, the output measurement unit 50 is disposed at a position where the laser beam 21 after passing through the condensing lens 23 can be measured, and the control unit 100 is arranged in the storage section 101. Based on the data 104 stored in , the balanced output 52 of the laser beam 21 is determined to be shorter than the predetermined time 53 necessary for the output to stabilize after the light receiving section 51 of the output measurement unit 50 starts receiving the laser beam 21. Since the prediction unit 102 is provided for predicting from the pre-equilibrium output 55 of the laser beam 21 at the prediction time 54, the equilibrium output 52 can be obtained in the prediction time 54 shorter than the predetermined time 53. As a result, the laser processing apparatus 1 has the effect of being able to accurately measure the balanced output 52 of the laser beam 21 after passing through the condenser lens 23 without reducing productivity.

Further, in the laser processing apparatus 1, when the control unit 100 processes the workpiece 200, the laser beam 21 is directed above the workpiece 200 held on the chuck table 10 and the light receiving section 51 of the output measurement unit 50. It further includes a movement control unit 103 that controls the movement distance of the X-axis movement unit 31 so that the laser beam 21 transmitted through the condensing lens 23 is irradiated onto the light receiving unit 51 of the output measurement unit 50 during the processing operation. can do.

Further, in the laser processing apparatus 1, since the movement control section 103 moves the laser beam irradiation unit 20 in the Y-axis direction relatively above the center of the light receiving section 51 of the output measuring unit 50, The laser beam irradiation unit 20 is momentarily stopped relative to the output measurement unit 50, and the laser beam 21 can be irradiated onto the light receiving section 51 for the predicted time period 54 without stopping the machining operation.

Further, the laser processing device 1 irradiates the laser beam 21 onto the planned dividing line 203 that is aligned with the light receiving section 51 of the output measuring unit 50 in the X-axis direction or on the planned dividing line 203 that is closest to the center of the light receiving section 51 in the Y-axis direction. At this time, the laser beam irradiation unit 20 is moved above the light receiving section 51 relative to the output measuring unit 50, and the laser beam 21 is irradiated onto the light receiving section 51. As a result, the laser processing apparatus 1 can suppress the time required to measure the output of the laser beam 21, and can improve productivity.

[Embodiment 2]
A laser processing apparatus according to a second embodiment of the present invention will be described based on the drawings. FIG. 6 is a perspective view showing an output measurement unit of the laser processing apparatus according to the second embodiment. FIG. 7 is a diagram showing data stored in the storage section of the control unit of the laser processing apparatus according to the second embodiment. In addition, in FIGS. 6 and 7, the same parts as in Embodiment 1 are denoted by the same reference numerals, and the description thereof will be omitted.

The laser processing device 1 according to the second embodiment includes an output measurement unit 50 housed in a housing 60 and disposed on the second moving plate 16, and a photodiode 70 disposed within the housing 60. This embodiment is the same as the first embodiment except that the data 104-2 (shown in FIG. 7) stored in the storage unit 101 is different.

As shown in FIG. 6, the housing 60 is disposed in a position overlapping the light receiving section 51 in the Z-axis direction and is formed in a box shape with an opening 61 through which the laser beam 21 passes. The photodiode 70 is housed in the housing 60 and includes a light receiving section 71 that receives scattered light 212 of the laser beam 21 scattered by the light receiving section 51 . The photodiode 70 converts the scattered light 212 of the laser beam 21 into an electrical signal according to the amount of light, and outputs the converted electrical signal to the control unit 100. The photodiode 70 converts the scattered light 212 of the laser beam 21 received by the light receiving section 71 into an electrical signal according to the amount of light, and outputs the converted electrical signal to the control unit 100. The time required for measurement is shorter than that of the output measurement unit 50, which is a power meter that is heated and converts the heat of the light receiving section 51 into an electrical signal (has a faster response speed). In the present invention, the position where the photodiode 70 is disposed is not limited to the position shown in FIG. 6, and may be, for example, the clamp part 12.

The control unit 100 converts the electrical signal from the photodiode 70 into the output of the laser beam 21 of scattered light 212 . The data 104-2 stored in the storage section 101 of the control unit 100 is, as shown in FIG. This is correlation data between the balanced output 52 and the output of the laser beam 21 of the scattered light 212 measured by the photodiode 70.

The horizontal axis in FIG. 7 shows the output of the laser beam 21 of the scattered light 212 obtained by converting the electrical signal from the photodiode 70, and the vertical axis in FIG. The balanced output 52 of the laser beam 21 obtained by converting the electrical signal from the output measurement unit 50, which is a power meter, is shown. For this purpose, the data 104-2 shown in FIG. This is the relationship with the balanced output 52.

The prediction unit 102 of the control unit 100 according to the second embodiment calculates the actual equilibrium output 52 of the laser beam 21 from the output of the laser beam 21 of the scattered light 212 based on the data 104-2 stored in the storage unit 101. It is something to do. Specifically, the prediction unit 102 calculates the equilibrium output 52 corresponding to the output of the laser beam 21 of the scattered light 212 obtained by converting the electrical signal from the photodiode 70 of the data 104-2, and The output 52 is calculated as the equilibrium output 52 of the actual laser beam 21.

In the laser processing apparatus 1 according to the second embodiment, the output measuring unit 50 is arranged at a position where it can measure the laser beam 21 after passing through the condensing lens 23, and detects the scattered light 212 of the laser beam 21 scattered by the light receiving section 51. The control unit 100 includes a photodiode 70 that receives light, and the control unit 100 outputs the balanced output 52 of the laser beam 21 based on the data 104-2 stored in the storage unit 101, and the output of the laser beam 21 of the scattered light 212 received by the photodiode 70. Since the prediction unit 102 is provided, the balanced output 52 can be obtained in a shorter time than the predetermined time 53. As a result, the laser processing apparatus 1 can measure the balanced output 52 of the laser beam 21 after passing through the condenser lens 23 without reducing productivity, and can suppress the time required to measure the balanced output 52.

Note that the present invention is not limited to the above embodiments. That is, various modifications can be made without departing from the gist of the invention. For example, in the present invention, the output measuring unit 50 is provided with a moving unit that moves the output measuring unit 50 in the Y-axis direction on the second moving plate 16, and the laser beam 21 is irradiated with the laser beam 21 on all the dividing lines 203 at any timing. The light receiving section 51 of the output measurement unit 50 may be irradiated with the laser beam 21. In this case, the laser beam 21 may be irradiated to the light receiving section 51 of the output measurement unit 50 at any timing before or after irradiating the laser beam 21 to all the planned dividing lines 203, and at least The laser beam 21 may be irradiated onto the light receiving section 51 of the output measurement unit 50 at any timing before or after the laser beam 21 is irradiated onto one dividing line 203.

1 Laser processing device 10 Chuck table 20 Laser beam irradiation unit 21 Laser beam 22 Laser oscillator 23 Condensing lens 31 X-axis movement unit (processing feed unit)
32 Y-axis movement unit (index feed unit)
50 Output measurement unit 51 Light receiving section 52 Equilibrium output (output at stable time when the output does not change, actual laser beam output)
53 Predetermined time (equivalent to the time required for the output to stabilize)
54 Prediction time (short time)
55 Pre-equilibrium output (short time laser beam output)
70 Photodiode 100 Control unit 101 Storage section 102 Prediction section 103 Movement control section 104 Data 104-2 Data (correlation data)
211 Focus point 212 Scattered light 200 Workpiece

Claims (2)

a chuck table that holds the workpiece;
a laser beam irradiation unit that irradiates the workpiece held on the chuck table with a pulsed laser beam;
a processing feed unit that relatively processes and feeds the chuck table and the laser beam irradiation unit;
an indexing and feeding unit that relatively indexes and feeds the chuck table and the laser beam irradiation unit;
an output measurement unit disposed adjacent to the chuck table and measuring the output of the laser beam;
a control unit that controls each component;
including;
The laser beam irradiation unit is
a laser oscillator,
a condensing lens that condenses a laser beam emitted from the laser oscillator and irradiates the workpiece,
The output measurement unit is disposed at a position where the laser beam after passing through the condenser lens can be measured,
The control unit includes:
a storage unit that stores as data a time since the output measurement unit was irradiated with the laser beam and a change in output due to a change in the time;
Based on the data stored in the storage unit,
a prediction unit that predicts the output of the laser beam at a stable time when the output of the laser beam does not change from the output of the laser beam for a time shorter than the time required for the output to become stable;
When processing the workpiece, the moving distance of the processing feed unit is adjusted so that the laser beam passes through the workpiece held on the chuck table and the light receiving section of the output measurement unit. a movement control unit for controlling;
A laser processing device characterized by having. a chuck table that holds the workpiece;
a laser beam irradiation unit that irradiates the workpiece held on the chuck table with a pulsed laser beam;
a processing feed unit that relatively processes and feeds the chuck table and the laser beam irradiation unit;
an indexing and feeding unit that relatively indexes and feeds the chuck table and the laser beam irradiation unit;
an output measurement unit disposed adjacent to the chuck table and measuring the output of the laser beam;
a control unit that controls each component;
including;
The laser beam irradiation unit is
a laser oscillator,
a condensing lens that condenses a laser beam emitted from the laser oscillator and irradiates the workpiece,
The output measurement unit is
disposed at a position where the laser beam after passing through the condensing lens can be measured;
a power meter equipped with a light receiving section that directly receives the laser beam;
a photodiode equipped with a light receiving section that receives scattered light of the laser beam;
The control unit includes:
a storage unit that stores correlation data between the actual balanced output of the laser beam measured by the power meter and the output of the scattered light laser beam measured by the photodiode;
a prediction unit that calculates an actual balanced output of the laser beam from the output of the laser beam of the scattered light based on the correlation data stored in the storage unit;
When processing the workpiece, the moving distance of the processing feed unit is controlled so that the laser beam passes through the workpiece held on the chuck table and the light receiving section of the output measurement unit. a movement control unit to control;
A laser processing device characterized by having.

Images