CN113523588A

CN113523588A - Laser processing apparatus

Info

Publication number: CN113523588A
Application number: CN202110387848.4A
Authority: CN
Inventors: 野村洋志; 松田匠悟; 增田幸容
Original assignee: Disco Corp
Current assignee: Disco Corp
Priority date: 2020-04-14
Filing date: 2021-04-12
Publication date: 2021-10-22
Also published as: JP7450447B2; TW202139274A; KR20210127610A; JP2021169107A

Abstract

The invention provides a laser processing device which can accurately measure the output of a laser beam transmitted through a condenser lens without reducing the production rate. The laser processing apparatus includes: a chuck table for holding a workpiece; a laser beam irradiation unit which irradiates a laser beam to a workpiece; an output measuring unit that measures an output of the laser beam; and a control unit that controls each component, the control unit including: a storage unit that stores, as data, a time from when the laser beam is irradiated to the output measurement unit and a change in output accompanying the change in time; and a prediction unit that predicts a balance output (52) of the output of the laser beam from the output of the laser beam (21) for a prediction time (54) shorter than a predetermined time (53) based on the data stored in the storage unit.

Description

Laser processing apparatus

Technical Field

The present invention relates to a laser processing apparatus.

Background

In order to process a workpiece such as a semiconductor wafer, there have been proposed a method of forming a processing groove by irradiating a laser beam having a wavelength that is absorptive to the workpiece and dicing the workpiece, and a method of converging a laser beam having a wavelength that is transmissive to the workpiece and irradiating the converged laser beam into the workpiece to form a modified layer as a division starting point and dividing the modified layer (see patent documents 1 and 2).

In the laser processing apparatus that performs the laser processing, if the output of the laser beam changes, a defective division of the workpiece may be caused. Therefore, it is 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 (for example, see patent document 3).

However, in a power meter shown in patent document 3 or the like generally used for measuring the output of a laser beam, it takes about 4 seconds from the start of measurement to make the output of the laser beam as a measurement result constant by heating the power meter by the laser beam received by the light receiving surface, converting the heat of the light receiving surface into an electric signal, and performing the output measurement. In order to measure the output of the laser beam, the power meter itself must be used to cut the optical path or interrupt the machining process to irradiate the power meter with the laser beam. Therefore, the power meter disclosed in patent document 3 or the like repeats the above measurement, and thus has a problem that the yield, which is the number of wafers processed per unit time, is reduced.

Therefore, a method of monitoring the output of the laser beam without interrupting the processing by using the transmitted light of the mirror has been proposed (see patent document 4).

Patent document 1: japanese patent laid-open publication No. 2003-320466

Patent document 2: japanese patent No. 3408805

Patent document 3: japanese laid-open patent publication No. 2009-291818

Patent document 4: japanese patent application No. 2019-155067

If the method disclosed in patent document 4 is used, the output can be measured while the workpiece is being processed. However, in the case of using the method disclosed in patent document 4, since the laser beam actually used for processing is the laser beam that has passed through the condenser lens and the laser beam to be measured and output is the laser beam before passing through the condenser lens, there is still a problem that the output of the laser beam actually irradiated to the object to be processed cannot be accurately measured even when a trouble such as adhesion of dirt to the condenser lens occurs.

Disclosure of Invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide a laser processing apparatus capable of accurately measuring the output of a laser beam transmitted through a condenser lens without lowering productivity.

In order to solve the above problems and achieve the object, a laser processing apparatus according to the present invention includes: a chuck table for holding a workpiece; a laser beam irradiation unit for irradiating a pulsed laser beam to the workpiece held by the chuck table; a processing and feeding unit which carries out processing and feeding of the chuck worktable and the laser beam irradiation unit oppositely; an index feeding unit which performs index feeding of the chuck table relative to the laser beam irradiation unit; an output measuring unit that measures an output of the laser beam; and a control unit that controls the respective components, the laser beam irradiation unit including: a laser oscillator; and a condensing lens that condenses the laser beam oscillated from the laser oscillator and irradiates the laser beam onto the workpiece, wherein the output measuring unit is disposed at a position where the laser beam passing through the condensing lens can be measured, and the control unit includes: a storage unit that stores, as data, a time from when the laser beam is irradiated to the output measurement unit and a change in output accompanying the change in time; and a prediction unit that predicts a stable output in which the output of the laser beam does not change any more from the output of the laser beam for a time shorter than a time required for the output to achieve the stability, based on the data stored in the storage unit.

In the laser processing apparatus, the output measuring unit may be disposed adjacent to the chuck table, and the control unit may further include a movement control unit that controls a movement distance of the processing feed unit so that the laser beam passes through the workpiece held by the chuck table and a light receiving unit of the output measuring unit when the workpiece is processed.

The laser processing apparatus of the present invention is characterized by comprising: a chuck table for holding a workpiece; a laser beam irradiation unit for irradiating a pulsed laser beam to the workpiece held by the chuck table; a processing and feeding unit which carries out processing and feeding of the chuck worktable and the laser beam irradiation unit oppositely; an index feeding unit which performs index feeding of the chuck table relative to the laser beam irradiation unit; an output measuring unit that measures an output of the laser beam; and a control unit that controls the respective components, the laser beam irradiation unit including: a laser oscillator; and a condensing lens for condensing the laser beam oscillated from the laser oscillator and irradiating the laser beam onto the workpiece, wherein the output measuring unit includes: a power meter which is disposed at a position where the laser beam having passed through the condenser lens can be measured, and which has a light receiving unit that directly receives the laser beam; and a photodiode having a light receiving part for receiving scattered light of the laser beam, wherein the control unit comprises: a storage unit for storing data relating to an actual output of the laser beam measured by the power meter and an output of the laser beam of scattered light measured by the photodiode; and a prediction unit that calculates an actual 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.

The invention of the application realizes the following effects: the output of the laser beam transmitted through the condenser lens can be accurately measured without lowering productivity.

Drawings

Fig. 1 is a perspective view showing a configuration example of a laser processing apparatus according to embodiment 1.

Fig. 2 is an explanatory view explaining a schematic configuration of a laser beam irradiation unit of the laser processing apparatus shown in fig. 1.

Fig. 3 is a diagram showing an example of output of a laser beam indicated by an electric signal output from the laser beam irradiation unit shown in fig. 2.

Fig. 4 is a plan view schematically showing the irradiation position of the laser beam by the laser beam irradiation unit on the workpiece of the laser processing apparatus shown in fig. 1.

Fig. 5 is a side view schematically showing the laser beam irradiated by the laser beam irradiation unit shown in fig. 4 and the workpiece.

Fig. 6 is a perspective view showing an output measuring unit of the laser processing apparatus according to embodiment 2.

Fig. 7 is a diagram showing data stored in a storage unit of a control unit of the laser processing device according to embodiment 2.

Description of the reference symbols

1: a laser processing device; 10: a chuck table; 20: a laser beam irradiation unit; 21: a laser beam; 22: a laser oscillator; 23: a condenser lens; 31: an X-axis moving unit (machining feed unit); 32: a Y-axis moving unit (index feeding unit); 50: an output measurement unit; 51: a light receiving section; 52: balanced output (output when stable with no change in output, actual output of laser beam); 53: a prescribed time (corresponding to the time required for the output to stabilize); 54: predicted time (short time); 55: output before balance (output of laser beam for short time); 70: a photodiode; 100: a control unit; 101: a storage unit; 102: a prediction unit; 103: a movement control unit; 104: data; 104-2: data (correlation data); 211: a light-gathering point; 212: scattering light; 200: a workpiece is processed.

Detailed Description

A mode (embodiment) 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. The components described below include components that can be easily assumed by those skilled in the art, and substantially the same components. The following structures may be combined as appropriate. Various omissions, substitutions, and changes in the structure may be made without departing from the spirit of the invention.

[ embodiment 1 ]

A laser processing apparatus according to embodiment 1 of the present invention will be described with reference to the drawings. First, the structure of the laser processing apparatus 1 according to embodiment 1 will be described. Fig. 1 is a perspective view showing a configuration example of a laser processing apparatus according to embodiment 1. A laser processing apparatus 1 shown in fig. 1 of embodiment 1 is an apparatus that irradiates a pulsed laser beam 21 to a workpiece 200 to perform laser processing on the workpiece 200.

(processed article)

The object 200 to be processed in the laser processing apparatus 1 shown in fig. 1 is a wafer such as a disc-shaped semiconductor wafer or an optical device wafer having a substrate 201 made of silicon, sapphire, gallium arsenide, or the like. As shown in fig. 1, a workpiece 200 includes: lines to divide 203 set in a grid pattern on the front surface 202 of the substrate 201; and a device 204 formed in a region divided by the line to divide 203. The Device 204 is, for example, an Integrated Circuit such as an IC (Integrated Circuit) or an LSI (Large Scale Integration), or an image sensor such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor).

In embodiment 1, an adhesive tape 208 having a disc shape with a diameter larger than the outer diameter of the workpiece 200 and having a ring frame 210 attached to the outer edge portion thereof is attached to the rear surface 205 on the rear side of the front surface 202 of the workpiece 200, and the workpiece 200 is supported in the opening 207 of the ring frame 210. In embodiment 1, the object 200 is divided into the devices 204 along the lines 203 to be divided.

As shown in fig. 1, the laser processing apparatus 1 includes: a chuck table 10, a laser beam irradiation unit 20, a moving unit 30, an imaging unit 40, an output measurement unit 50, and a control unit 100, wherein the chuck table 10 holds a workpiece 200 by a holding surface 11.

The chuck table 10 holds the workpiece 200 by the holding surface 11. The holding surface 21 is formed in a disk 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 sucks and holds the workpiece 200 placed on the holding surface 11. In embodiment 1, the holding surface 11 is a plane parallel to the horizontal direction. A plurality of clamp portions 12 are arranged around the chuck table 10, and the clamp portions 12 clamp an annular frame 210 that supports the workpiece 200 in the opening 207.

The chuck table 10 is rotated by the rotating and moving unit 34 of the moving unit 30 about an axis perpendicular to the holding surface 11 and parallel to the Z-axis direction parallel to the vertical direction. The chuck table 10 is moved in an X-axis direction parallel to the horizontal direction by the X-axis moving unit 31 of the moving unit 30 together with the rotation moving unit 34, and is moved in a Y-axis direction parallel to the horizontal direction and perpendicular to the X-axis direction by the Y-axis moving unit 32.

The laser beam irradiation unit 20 is a unit that irradiates the workpiece 200 held on the chuck table 10 with a pulse-shaped laser beam 21. In embodiment 1, the laser beam irradiation unit 20 is a laser beam irradiation member that irradiates a pulsed laser beam 21 having a wavelength that is transparent to the workpiece 200 to form a modified layer that serves as a fracture starting point inside the workpiece 200. The modified layer refers to a region where density, refractive index, mechanical strength, and other physical properties are in a state different from those of the surroundings. The modified layer is, for example, a melt-processed region, a crack region, an insulation breakdown region, a refractive index change region, a region in which these regions are mixed, or the like. In an embodiment, the modified layer has a lower mechanical strength than other portions of the substrate 201.

In embodiment 1, the laser beam irradiation means 20 irradiates the laser beam 21 having a wavelength that is transparent to the workpiece 200, but in the present invention, the workpiece 200 may be ablated by irradiating the laser beam 21 having an absorptive wavelength. In embodiment 1, as shown in fig. 1, a part of the laser beam irradiation unit 20 is supported by the elevating member 4 that moves in the Z-axis direction by the Z-axis moving unit 33 of the moving unit 30 provided on the standing wall 3 standing from the apparatus main body 2.

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

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

The condenser lens 23 is disposed at a position facing the holding surface 11 of the chuck table 10 in the Z-axis direction, and condenses the laser beam 21 to the condensing point 211 by transmitting the laser beam 21 oscillated from the laser oscillator 22.

As shown in fig. 2, the attenuator 24 has a hollow motor 26, a λ/2 wavelength plate 27, a beam splitter 28, and a beam damper 29. The hollow motor 26 is formed in an annular shape, and the laser beam 21 oscillated by the laser oscillator 22 passes through the inside. The λ/2 wavelength plate 27 is rotated around the optical axis of the laser beam 21 oscillated from the laser oscillator 22 by the hollow motor 26. The λ/2 wavelength plate 27 emits the laser beam 21 by giving a phase difference λ/2(180 °).

The beam splitter 28 reflects the S-polarized laser beam 21 of the laser beams 21 having 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 laser beam 21 of S-polarized light reflected by the beam splitter 28.

The moving unit 30 moves the laser beam irradiation unit 20 and the chuck table 10 relative to each other 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 mobile unit 30 includes: an X-axis moving unit 31 as a processing feeding unit that moves the chuck table 10 in the X-axis direction; a Y-axis moving unit 32 as an index feeding unit that moves the chuck table 10 in the Y-axis direction; a Z-axis moving unit 33 that moves the condenser lens 23 included in the laser beam irradiation unit 20 in the Z-axis direction; and a rotation moving unit 34 that rotates the chuck table 10 about an axis parallel to the Z-axis direction.

The Y-axis moving unit 32 is a unit that indexes the chuck table 10 relative to the laser beam irradiation unit 20. In embodiment 1, the Y-axis moving unit 32 is provided in the apparatus main body 2 of the laser processing apparatus 1. The Y-axis moving unit 32 supports the moving plate 15 supporting the X-axis moving unit 31 to be movable in the Y-axis direction.

The X-axis moving unit 31 is a unit that processes and feeds the chuck table 10 and the laser beam irradiation unit 20 relatively. The X-axis moving unit 31 is provided on the moving plate 15. The X-axis moving unit 31 supports the second moving plate 16 supporting the rotating unit 34 to be movable in the X-axis direction, wherein the rotating unit 34 rotates the chuck table 10 around an axis parallel to the Z-axis direction. The Z-axis moving unit 33 is provided on the standing wall 3 and supports the elevating member 4 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 have: a known ball screw provided to be rotatable about an axis; a known pulse motor that rotates a ball screw around an axis; and a known guide rail that supports the moving

plates

15 and 16 to be movable in the X-axis direction or the Y-axis direction and supports the vertically movable member 4 to be movable in the Z-axis direction.

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

The imaging unit 40 images the workpiece 200 held on the chuck table 10. The imaging unit 40 includes an imaging element such as a CCD (Charge Coupled Device) imaging element or a CMOS (Complementary Metal Oxide Semiconductor) imaging element for imaging the workpiece 200 held on the chuck table 10. In embodiment 1, the imaging unit 40 is attached to the front end of the housing of the laser beam irradiation unit 20 and is disposed at a position parallel to the condenser lens 23 of the laser beam irradiation unit 20 in the X-axis direction as shown in fig. 2. The imaging unit 40 images the workpiece 200, obtains 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.

The output measuring unit 50 is a unit that measures the output of the laser beam 21. The output measuring unit 50 has a light receiving unit 51, and the light receiving unit 51 receives the laser beam 21 emitted from the laser oscillator 22 and propagating through the attenuator 24, the mirror 25, the condenser lens 23, and the like. The light receiving unit 51 is disposed at a position spaced apart from a converging point 211 set in the workpiece 200 held by the chuck table 10 by a predetermined distance in the Z-axis direction. In embodiment 1, the light receiving unit 51 is disposed below the focal point 211 by a predetermined distance.

The output measuring unit 50 is a power meter that heats the light receiving part 51 by the laser beam 21 and converts the heat of the light receiving part 51 into an electric signal. The output measuring unit 50 outputs the converted electric signal toward the control unit 100. In embodiment 1, the electrical signal output by the output measurement unit 50 corresponds to the output of the laser beam 21 received by the light receiving unit 51. In this way, the output measuring unit 50 measures the output of the laser beam 21 by outputting the above-described electric signal to the control unit 100.

In embodiment 1, the output measuring unit 50 is provided with the light receiving unit 51 facing upward on the second moving plate 16. In embodiment 1, the output measuring unit 50 is disposed at a position where the light receiving unit 51 is provided on the second moving plate 16 so as to face upward and can measure the laser beam 21 having passed through the condenser lens 23. In embodiment 1, in the output measuring unit 50, the light receiving unit 51 is arranged at a position juxtaposed in the X axis direction with at least one line 203 to divide the workpiece 200 held by the holding surface 11. As described above, in the present invention, the light receiving unit 51 is disposed at a position parallel to the X axis direction with respect to at least one line to divide 203 of the workpiece 200 held by the holding surface 11, and the output measuring unit 50 is disposed adjacent to the chuck table 10.

The control unit 100 controls the above-described components of the laser processing apparatus 1, and causes the laser processing apparatus 1 to perform a processing operation on the workpiece 200. The control unit 100 is a computer having 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 interface device. The arithmetic processing device of the control unit 100 performs arithmetic processing in accordance with a computer program stored in the storage device, and outputs a control signal for controlling the laser processing apparatus 1 to the above-described constituent elements of the laser processing apparatus 1 via the input/output interface device, thereby realizing the function of the control unit 100.

The control unit 100 is connected to a display unit 110 including a liquid crystal display device or the like for displaying a state of a machining operation, an image, and the like, and an input unit, not shown, used by an operator for registering machining content information and the like. The input unit is configured by at least one of an external input device such as a touch panel and a keyboard provided in the display unit 110.

The control unit 100 converts the electric signal from the output measuring unit 50 into the output of the laser beam 21. As shown by the broken line in fig. 3, the output measuring means 50 is a so-called power meter in which the light receiving unit 51 is heated by the laser beam 21 and converts heat into an electric signal corresponding to the output of the laser beam 21, and therefore, it takes a predetermined time 53 (corresponding to the time required for the output to stabilize) from the time when the light receiving unit 51 starts receiving the laser beam 21 until the output reaches an equilibrium output 52 (the output at the time of stabilization in which the output does not change any more, the output not rising further). The balance output 52 is an output of the laser beam 21 of the laser beam irradiation unit 20 which the output measurement unit 50 wants to measure. The horizontal axis in fig. 3 represents the elapsed time from the start of receiving the laser beam 21 by the light receiving unit 51, and the vertical axis in fig. 3 represents the output of the laser beam 21 converted by the control unit 100.

As shown in fig. 1, the control unit 100 includes a storage unit 101 and a prediction unit 102. The storage unit 101 stores, as data 104, an elapsed time from when the light receiving unit 51 of the output measurement unit 50 receives the laser beam 21 and a change in the output of the laser beam 21 after conversion of the electric signal from the output measurement unit 50 with the change in the elapsed time. That is, the storage unit 101 stores the same data 104 as data for predicting the body temperature before the so-called predicted thermometer reaches the equilibrium temperature. For example, the data 104 is a mathematical expression 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 measurement unit 50 at the predicted time 54 (shown in fig. 3). 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 balance output 52 in which the output of the laser beam 21 does not change any more, based on the pre-balance output 55 that is the irradiation of the laser beam 21 for the prediction time 54 shorter than the predetermined time 53 required for the output to achieve the stability. Specifically, the prediction unit 102 predicts the balance output 52 as shown by a solid line in fig. 3, based on the pre-balance output 55 of the laser beam 21 obtained by converting the electric signal from the output measurement unit 50 at the prediction time 54 and referring to the data 104 stored in the storage unit 101. In this way, the prediction unit 102 of the control unit 100 predicts the balanced output 52 before reaching the balanced output 52.

The control unit 100 further includes a movement control unit 103. When the object 200 is to be processed by irradiating the laser beam 21 on each of the lines 203, the movement control unit 103 controls the movement distance of the chuck table 10 in the X direction by the X-axis moving unit 31 so that the laser beam 21 passes through the object 200 held by the chuck table 10 and the light receiving unit 51 of the output measuring unit 50. Specifically, the movement control unit 103 calculates, from the processing content information, a line to divide 203 which is aligned in the X-axis direction with the light receiving unit 51 of the output measuring unit 50 among the lines to divide 203 of the object 200 held by the chuck table 10.

When there is one line 203 aligned in the X-axis direction with the light receiving unit 51 of the output measuring unit 50 among the lines 203 to divide the workpiece 200 held by the chuck table 10, the movement control unit 103 controls the movement unit 30 so as to be directed upward from the outer edge of the workpiece 200 toward the light receiving unit 51 of the output measuring unit 50 when the laser beam 21 is irradiated onto the one line 203 to divide. When the laser beam irradiation means 20 is directed from the outer edge of the workpiece 200 to above the light receiving unit 51 of the output measurement means 50, the control means 100 temporarily stops the irradiation of the laser beam 21 and restarts the irradiation of the laser beam 21 on the light receiving unit 51.

The movement control unit 103 controls the moving unit 30 so that the line to be divided 203 to be processed next is positioned below the laser beam irradiation unit 20 in a state where the laser beam irradiation unit 20 is positioned on the light receiving unit 51, and controls the moving unit 30 so that the laser beam irradiation unit 20 is directed above the line to be divided 203 to be processed next after the laser beam irradiation unit 20 and the chuck table 10 are relatively moved in the Y axis direction. When the laser beam irradiation unit 20 is retracted from above the light receiving unit 51, the control unit 100 stops the 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 unit 51, the laser beam 21 can be continuously irradiated when the output is weak.

Further, when there are a plurality of lines 203 aligned in the X axis direction with the light receiving unit 51 of the output measuring unit 50 among the lines 203 to divide the workpiece 200 held by the chuck table 10, the movement control unit 103 calculates the line 203 closest to the center of the light receiving unit 51 in the Y axis direction, and controls the respective components as described above when irradiating the laser beam 21 on the line 203 closest to the line. As described above, in the embodiment, when the laser beam 21 is irradiated onto any one of the lines to divide 203 of the object 200, even if the laser beam passes through the line to divide 203, the movement control unit 103 relatively moves the chuck table 10 and the laser beam irradiation unit 20 in the X-axis direction which is the processing feed direction, and irradiates the light receiving unit 51 with the laser beam 21. In embodiment 1, 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 index feeding direction, while irradiating the light receiving unit 51 with the laser beam 21.

The function of the storage unit 101 is realized by the above-described storage device. The functions of the prediction unit 102 and the movement control unit 103 are realized by an arithmetic processing device that performs arithmetic processing in accordance with a computer program stored in a storage device.

Next, a machining operation of the laser machining apparatus 1 will be described. Fig. 4 is a plan view schematically showing the irradiation position of the laser beam by the laser beam irradiation unit on the workpiece of the laser processing apparatus shown in fig. 1. Fig. 5 is a side view schematically showing the laser beam irradiated by the laser beam irradiation unit shown in fig. 4 and the workpiece. In fig. 4, the line to divide 203 is omitted.

In the laser processing apparatus 1 described above, the operator registers the 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 when the control unit 100 receives a processing operation start instruction from the input unit by the operator, the laser processing apparatus 1 starts the processing operation based on the registered processing content information.

In the machining operation, the laser machining apparatus 1 sucks and holds the workpiece 200 on the holding surface 11 of the chuck table 10 via the adhesive tape 208, and sandwiches the ring frame 210 with the jig 12. Next, the moving unit 30 moves the chuck table 10 downward of the imaging unit 40, and the imaging unit 40 images the workpiece 200. The laser processing apparatus 1 performs alignment based on an image captured by the imaging unit 40.

The laser processing apparatus 1 relatively moves the laser beam irradiation unit 20 and the object 200 along the lines to divide 203 by the movement unit 30 based on the processing content information, and irradiates the pulsed laser beam 21 from the laser beam irradiation unit 20 to the lines to divide 203. In embodiment 1, as shown in fig. 2, the laser processing apparatus 1 sets the converging point 211 of the laser beam 21 inside the substrate 201 of the object 200, and irradiates the lines to be divided 203 with the laser beam 21, thereby forming a modified layer inside the substrate 201 along the lines to be divided 203. When a modified layer is formed inside the substrate 201 along all the lines to divide 203, the laser processing apparatus 1 stops the irradiation of the laser beam 21 and ends the processing operation.

In the machining operation, the laser machining apparatus 1 moves the laser beam irradiation unit 20 above the planned dividing lines 203 relative to the chuck table 10 in the X-axis direction while maintaining the position of the converging point 211 in the Z-axis direction, and moves the laser beam irradiation unit 20 relative to the chuck table 10 in the Y-axis direction at a position located at a predetermined distance on the outer peripheral side of the end portions of the planned dividing lines 203. During the machining operation, the laser machining 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 relative to the chuck table 10 above the workpiece 200, and stops the irradiation of the laser beam 21 at a position indicated by a broken line 301 in fig. 4 where the laser beam irradiation unit moves relative to the chuck table 10 above the outer periphery of the workpiece 200 by a predetermined distance.

In the machining operation, when the laser processing apparatus 1 irradiates the laser beam 21 onto the line 203 to be divided aligned in the X-axis direction with the light receiving unit 51 of the output measuring unit 50 or the line 203 to be divided closest to the center in the Y-axis direction of the light receiving unit 51 calculated by the movement control unit 103, the laser processing apparatus moves the laser beam irradiation unit 20 relatively in the X-axis direction to above the light receiving unit 51 of the output measuring unit 50, irradiates the laser beam 21 from the laser beam irradiation unit 20 above the light receiving unit 51 of the output measuring unit 50, and moves the laser beam irradiation unit 20 relatively in the Y-axis direction at a position above the center of the light receiving unit 51 of the output measuring unit 50, as shown by a solid line 300 in fig. 4 and 5. In the present invention, it is preferable to temporarily stop the relative movement of the laser beam irradiation unit 20 with respect to the light receiving unit 51 above the light receiving unit 51, but the measurement may be performed by relatively passing the laser beam irradiation unit 20 above the light receiving unit 51.

In the laser processing apparatus 1, the light receiving unit 51 of the output measuring unit 50 receives the laser beam 21 and outputs an electric signal corresponding to the output of the laser beam 21 to the control unit 100. In embodiment 1, the light receiving unit 51 of the output measuring unit 50 is disposed below the focal point 211 by a predetermined distance, and therefore receives the laser beam 21 that diverges beyond the focal point 211.

The prediction unit 102 of the control unit 100 of the laser processing apparatus 1 converts the electric signal from the light receiving unit 51 at the predicted time 54 from the start of light reception by the light receiving unit 51 into the pre-balance output 55 of the laser beam 21, and predicts the balance output 52 as shown by the solid line in fig. 3, based on the converted pre-balance output 55 of the laser beam 21 and with reference to the data 104 stored in the storage unit 101.

As described above, in the laser processing apparatus 1 according to embodiment 1, the output measuring means 50 is disposed at a position where the laser beam 21 having passed through the condenser lens 23 can be measured, and the control means 100 has the predicting section 102, and the predicting section 102 predicts the equilibrium output 52 of the laser beam 21 based on the pre-equilibrium output 55 of the laser beam 21 which is output for the prediction time 54 shorter than the predetermined time 53 required for achieving the stability from the start of the light reception of the laser beam 21 by the light receiving section 51 of the output measuring means 50 based on the data 104 stored in the storage section 101, so that the equilibrium output 52 can be obtained for the prediction time 54 shorter than the predetermined time 53. As a result, the laser processing apparatus 1 achieves the following effects: the balanced output 52 of the laser beam 21 after passing through the condenser lens 23 can be accurately measured without lowering productivity.

Further, the laser processing apparatus 1 further includes a movement control unit 103, and when the control unit 100 processes the workpiece 200, the movement control unit 103 controls the movement distance of the X-axis moving unit 31 so that the laser beam 21 passes above the workpiece 200 held on the chuck table 10 and the light receiving unit 51 of the output measuring unit 50, and therefore, the laser beam 21 transmitted through the condenser lens 23 can be irradiated to the light receiving unit 51 of the output measuring unit 50 during the processing operation.

In the laser processing apparatus 1, the movement control unit 103 moves the laser beam irradiation unit 20 in the Y-axis direction relatively above the center of the light receiving unit 51 of the output measurement unit 50, so that the laser beam irradiation unit 20 is stopped instantaneously relatively to the output measurement unit 50 above the center of the light receiving unit 51, and the laser beam 21 of the predicted time 54 can be irradiated to the light receiving unit 51 without stopping the processing operation.

In the laser processing apparatus 1, when the laser beam 21 is irradiated onto the line to divide 203 juxtaposed in the X-axis direction with the light receiving unit 51 of the output measuring unit 50 or the line to divide 203 closest to the center in the Y-axis direction of the light receiving unit 51, the laser beam irradiating unit 20 is moved above the light receiving unit 51 relative to the output measuring unit 50, and the light receiving unit 51 is irradiated with the laser beam 21. As a result, the laser processing apparatus 1 can suppress the time required for measuring the output of the laser beam 21, and can improve the productivity.

[ embodiment 2 ]

A laser processing apparatus according to embodiment 2 of the present invention will be described with reference to the drawings. Fig. 6 is a perspective view showing an output measuring unit of the laser processing apparatus according to embodiment 2. Fig. 7 is a diagram showing data stored in a storage unit of a control unit of the laser processing device according to embodiment 2. In fig. 6 and 7, the same components as those in embodiment 1 are denoted by the same reference numerals, and description thereof is omitted.

The laser processing apparatus 1 of embodiment 2 is the same as embodiment 1 except for the following: the output measuring unit 50 is housed in the case 60 and arranged on the second moving plate 16, and the laser processing apparatus 1 includes the photodiode 70 arranged in the case 60, and differs in data 104-2 (shown in fig. 7) stored in the storage unit 101.

As shown in fig. 6, the housing 60 is formed in a box shape provided with an opening 61 through which the laser beam 21 passes, and disposed at a position overlapping the light receiving unit 51 in the Z-axis direction. The photodiode 70 is housed in the housing 60, and has a light receiving unit 71 that receives the scattered light 212 of the laser beam 21 scattered by the light receiving unit 51. The photodiode 70 converts the scattered light 212 of the laser beam 21 into an electric signal corresponding to the amount of light, and outputs the converted electric signal to the control unit 100. Since the photodiode 70 converts the scattered light 212 of the laser beam 21 received by the light receiving section 71 into an electric signal corresponding to the light amount and outputs the converted electric signal to the control unit 100, the time required for measurement is shorter (the response speed is higher) than that of the output measurement unit 50 which is a power meter that heats the light receiving section 51 with the laser beam 21 and converts the heat of the light receiving section 51 into an electric signal. 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 disposed in the jig 12, for example.

The control unit 100 converts the electrical signal from the photodiode 70 into an output of the laser beam 21 of scattered light 212. As shown in fig. 7, the data 104-2 stored in the storage unit 101 of the control unit 100 is data relating the actual balance output 52 of the laser beam 21 measured by the output measuring unit 50 of the power meter that receives the laser beam 21 from the light receiving unit 51 and the output of the laser beam 21 of the scattered light 212 measured by the photodiode 70.

The horizontal axis of fig. 7 represents the output of the laser beam 21 of the scattered light 212 obtained by converting the electric signal from the photodiode 70, and the vertical axis of fig. 7 represents the balanced output 52 of the laser beam 21 obtained by converting the electric signal from the output measuring means 50, which is a power meter receiving the laser beam 21 from the light receiving unit 51. Accordingly, the data 104-2 shown in fig. 7 is a relationship between the output of the laser beam 21 of the scattered light 212 received by the light receiving section 71 of the photodiode 70 and the equilibrium output 52 of the laser beam 21 received by the light receiving section 51 of the output measuring unit 50.

The prediction unit 102 of the control unit 100 according to embodiment 2 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. Specifically, the prediction unit 102 calculates the balance output 52 of the data 104-2 corresponding to the output of the laser beam 21 of the scattered light 212 obtained by converting the electric signal from the photodiode 70, and calculates the calculated balance output 52 as the actual balance output 52 of the laser beam 21.

In the laser processing apparatus 1 according to embodiment 2, the output measuring means 50 is disposed at a position where the laser beam 21 having passed through the condenser lens 23 can be measured, and includes the photodiode 70 that receives the scattered light 212 of the laser beam 21 scattered by the light receiving unit 51, and the control means 100 includes the predicting unit 102, and the predicting unit 102 predicts the equilibrium output 52 of the laser beam 21 from the output of the laser beam 21 of the scattered light 212 received by the photodiode 70 based on the data 104-2 stored in the storage unit 101, and thus the equilibrium output 52 can be obtained in a time shorter than the predetermined time 53. As a result, the laser processing apparatus 1 can measure the balanced output 52 of the laser beam 21 having passed through the condenser lens 23 without lowering productivity, and can suppress the time required for measuring the balanced output 52.

The present invention is not limited to the above embodiments. That is, various modifications can be made without departing from the scope of the present invention. For example, in the present invention, a moving means for moving the output measuring means 50 in the Y axis direction on the second moving plate 16 may be provided, and the laser beam 21 may be irradiated to the light receiving unit 51 of the output measuring means 50 at an arbitrary timing before and after the laser beam 21 is irradiated to all the lines to divide 203. In this case, the laser beam 21 may be irradiated to the light receiving unit 51 of the output measuring unit 50 at an arbitrary timing before and after the laser beam 21 is irradiated to all the lines to divide 203, or the laser beam 21 may be irradiated to the light receiving unit 51 of the output measuring unit 50 at an arbitrary timing before and after the laser beam 21 is irradiated to at least one line to divide 203 of all the lines to divide 203.

Claims

1. A laser processing apparatus is characterized in that,

the laser processing apparatus includes:

a chuck table for holding a workpiece;

a laser beam irradiation unit for irradiating a pulsed laser beam to the workpiece held by the chuck table;

a processing and feeding unit which carries out processing and feeding of the chuck worktable and the laser beam irradiation unit oppositely;

an index feeding unit which performs index feeding of the chuck table relative to the laser beam irradiation unit;

an output measuring unit that measures an output of the laser beam; and

a control unit for controlling each component,

the laser beam irradiation unit includes:

a laser oscillator; and

a condensing lens for condensing the laser beam oscillated from the laser oscillator and irradiating the laser beam onto the workpiece,

the output measuring unit is arranged at a position where the laser beam having passed through the condenser lens can be measured,

the control unit has:

a storage unit that stores, as data, a time from when the laser beam is irradiated to the output measurement unit and a change in output accompanying the change in time; and

and a prediction unit that predicts a stable output in which the output of the laser beam does not change any more from the output of the laser beam for a time shorter than a time required for the output to achieve the stability, based on the data stored in the storage unit.

2. Laser processing apparatus according to claim 1,

the output measuring unit is disposed adjacent to the chuck table,

the control unit further has a movement control portion that controls a movement distance of the processing feed unit so that the laser beam passes through the object held by the chuck table and the light receiving portion of the output measuring unit when the object is processed.

3. A laser processing apparatus is characterized in that,

the laser processing apparatus includes:

a chuck table for holding a workpiece;

an output measuring unit that measures an output of the laser beam; and

a control unit for controlling each component,

the laser beam irradiation unit includes:

a laser oscillator; and

the output measurement unit includes:

a power meter which is disposed at a position where the laser beam having passed through the condenser lens can be measured, and which has a light receiving unit that directly receives the laser beam; and

a photodiode having a light receiving part for receiving the scattered light of the laser beam,

the control unit has:

a storage unit for storing data relating to an actual output of the laser beam measured by the power meter and an output of the laser beam of scattered light measured by the photodiode; and

and a prediction unit that calculates an actual 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.