Laser processing apparatus

Abstract

To provide a laser processing apparatus capable of suppressing misalignment between laser beams caused by vibration.SOLUTION: A laser processing apparatus according to the embodiment comprises: an optical system having a laser light-emitting laser light source, an optical forming element forming a processing laser light from the laser light and a focusing lens for focusing processing laser light onto the workpiece; a transfer mechanism for transferring the workpiece; sensing means for detecting vibration; and a vibration suppression mechanism for suppressing the vibration based on the measurement results of the sensing means.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a laser processing device. [Background technology]

[0002] In the field of semiconductors, wafers (semiconductor wafers) are known that form multiple devices using a laminate consisting of a low-dielectric-constant insulating film (low-k film) and a functional film that forms circuits on the surface of a substrate such as silicon.

[0003] In such a wafer, a plurality of devices are partitioned in a lattice pattern by lattice streets, and the individual devices are manufactured by dividing the wafer along the planned dividing lines.

[0004] Low-k films tend to peel easily, so dicing using a blade can result in the film peeling off. To address this issue, there is a method in which two first grooves that divide the low-k film are formed on both sides of the intended separation area using laser ablation, and then a second groove is formed between the two first grooves.

[0005] When performing laser processing on a workpiece, it is required that the processing time be short and that the thermal impact on divided devices be suppressed. To shorten the processing time, it is possible to perform the processing in one pass, but in this case the energy per beam must be increased. Increasing the energy per beam makes it easier for heat to be generated during laser processing, increasing the impact on the device. On the other hand, in order to reduce the thermal impact on the device, it is possible to reduce the energy per beam and perform laser processing in multiple passes. However, in this case it becomes difficult to shorten the processing time.

[0006] Patent Document 1 discloses a laser processing device that, as a technology capable of maintaining the processing quality of the processed groove while preventing an increase in takt time, includes a branching element that branches a second laser beam into multiple branched beams along the processing feed direction, and a second condenser lens that focuses the multiple branched beams branched by the branching element onto the street to be processed. The laser processing device satisfies the following relationship: L is the branching distance, which is the distance between adjacent leading and trailing spots among the spots of each branched beam focused onto the street by the second condenser lens; V is the processing speed, which is the speed of relative movement; and τ is the time until the trailing spot overlaps the processing position of the leading spot. When τ1 is the threshold time at which a deterioration in the processing quality of the second groove occurs, the device satisfies the following relationship: τ=L / V. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2022-71402 Summary of the Invention [Problem to be solved by the invention]

[0008] Currently, there is a demand for faster stage axial speeds and accelerations to improve throughput. Increasing the stage axial speeds and accelerations increases the impact of machine vibrations due to reaction forces during stage operation. When a single laser light source is used to form the first and second grooves described above, the vibration-induced deviations during movement in the processing direction between each process are similar. However, when processing is performed using multiple branched laser beams, as in Patent Document 1, the positions of the processing points (spots) differ in the processing direction. Therefore, even when operating on the same time axis, the effects of vibration are not uniform, resulting in differences in the laser beam deviations due to vibration at each processing point. Furthermore, when multiple laser light sources are used, there are two or more optical paths to each processing point, and therefore the optical system deviations due to vibration are independent of each other. Similarly, differences in the laser beam deviations due to vibration at each processing point occur.

[0009] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a laser processing device that can suppress deviations between laser beams due to vibrations. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention proposes the following means. <1> The laser processing apparatus according to aspect 1 of the present invention comprises: a laser light source that emits laser light; a light forming element that forms a processed laser beam from the laser beam; a condenser lens that condenses the processing laser light onto a workpiece; an optical system comprising: a moving mechanism for moving the workpiece; a sensing means for detecting vibration; a vibration suppression mechanism that suppresses the vibration based on the measurement result of the sensing means; Equipped with. <2> A second aspect of the present invention is the laser processing apparatus of the first aspect, Two of the optical systems are provided, The optical system may include the sensing means for measuring a deviation of the optical system. <3> A third aspect of the present invention is the laser processing apparatus of the first or second aspect, The vibration suppression mechanism may include a counterweight that is movable in the same direction as the workpiece. <4> A fourth aspect of the present invention is the laser processing apparatus of the first or second aspect, a base on which the moving mechanism is mounted; a stand on which the base is mounted; The machine may further include an actuator capable of moving the base in a direction opposite to the direction of movement of the workpiece. <5> A fifth aspect of the present invention is the laser processing apparatus of the second aspect, wherein the sensing means may measure a positional deviation of at least one of the laser light and the processing laser light caused by the vibrations generated by the operation of the moving mechanism. <6> A sixth aspect of the present invention is that, in the laser processing apparatus of the second aspect, the sensing means may measure the positional deviation of the laser light and the processing laser light due to the vibration generated by the operation of the moving mechanism, and detect the angular deviation of the laser light. [Effects of the Invention]

[0011] According to the above aspects of the present invention, it is possible to provide a laser processing device that can suppress misalignment between the laser beams due to vibration. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic perspective view of a laser processing device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a plan view of a wafer that is a workpiece. [Figure 3] FIG. 10 is an explanatory diagram for explaining laser processing along the outgoing direction X1. [Figure 4] 10 is an explanatory diagram for explaining laser processing along the backward direction X2. FIG. [Figure 5] FIG. 2 is a plan view of the laser processing apparatus of FIG. [Figure 6] FIG. 1 is a block diagram illustrating an example of a laser optical system. [Figure 7] 10A and 10B are diagrams for explaining the deviation amount and deviation angle of laser light; [Figure 8] 1 is a flowchart of a laser processing method according to an embodiment of the present invention. [Figure 9] FIG. 9(a) is an example of the waveform of the laser light deviation measured by the sensor, and FIG. 9(b) is an example of the waveform of the laser light deviation measured by the sensor after vibration is suppressed. [Figure 10] FIG. 10 is a perspective view of a modified example of the laser processing device. [Figure 11] 10 is a plan view of the laser processing apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A laser processing apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

[0014] [Laser processing overview] In this embodiment, the laser beam for processing emitted from the laser light source is split into multiple beams, thereby shortening the laser processing time. Furthermore, the deviation of the laser beam caused by vibrations accompanying the movement of the stage is measured by a sensor, and the vibrations are suppressed based on the measurement results. This reduces the deviation between the laser beams.

[0015] First Embodiment [Laser processing equipment] Next, an example of a laser processing device will be described with reference to FIG.

[0016] FIG. 1 is a schematic perspective view of a laser processing apparatus according to one embodiment of the present invention. As shown in FIG. 1, the laser processing apparatus 1 performs laser processing (laser ablation processing) on ​​a wafer W1 as a pre-process before dividing the wafer W1 into a plurality of chips C (see FIG. 2). Here, the X direction, Y direction, and Z direction in the figure are defined. The X direction and Y direction are directions along the surface W1a of the wafer W1, which will be described later. The Y direction is a direction that intersects (e.g., is perpendicular to) the X direction. The Z direction is a direction that intersects (e.g., is perpendicular to) the X direction and the Y direction, and is the thickness direction of the wafer W1. The X direction corresponds to the processing feed direction in the present invention.

[0017] Figure 2 is a plan view of a wafer W1, which is a workpiece. As shown in Figure 2, the wafer W1 is a laminate in which a low-k film and a functional film that forms a circuit are laminated on the surface of a substrate such as silicon. The wafer W1 is divided into multiple regions by multiple streets S (planned division lines) arranged in a grid pattern. Each of these divided regions is provided with a device D that constitutes a chip C.

[0018] The laser processing device 1 performs laser processing on the wafer W1 along each street S, as indicated by the parenthesized numbers (1) to (4) in the figure, thereby removing the low-k film, part of the base material, etc.

[0019] At this time, in order to reduce the processing time of the laser processing of the wafer W1, the laser processing apparatus 1 may alternately switch the relative movement direction when moving the laser optical system 14 described below in the X direction relative to the wafer W1 for each street S.

[0020] For example, when laser processing is performed along odd-numbered streets S such as those indicated by parenthesized numbers (1) and (3) in Fig. 2, the laser optical system 14 is moved relative to the wafer W1 in a forward direction X1, which is one side of the X direction. When laser processing is performed along even-numbered streets S such as those indicated by parenthesized numbers (2) and (4) in Fig. 2, the laser optical system 14 is moved relative to the wafer W1 in a backward direction X2, which is opposite to the forward direction X1.

[0021] FIG. 3 is an explanatory diagram for explaining laser processing along the outgoing direction X1. 4 is an explanatory diagram for explaining laser processing along the even-numbered backward direction X2. As shown in FIGS. 3 and 4, in this embodiment, the laser processing involves simultaneously (concurrently) performing edge cutting processing to form two parallel, thin first grooves G1 along the street S so as not to affect the chip side with the processing, and hollowing processing to remove unnecessary material inside the first grooves G1 to expose the base material (e.g., silicon). The edge cutting processing is laser processing performed using two first processing laser beams (split lasers) LA1, and forms two parallel edge cutting grooves G1 (two first grooves G1; ablation grooves) along the street S.

[0022] In the laser processing device 1, in either case where the laser optical system 14 is moved relative to the wafer W1 in the forward direction X1 or in the backward direction X2, the edge cutting process is performed before the hollowing process.

[0023] Fig. 5 is a plan view of the laser processing apparatus 1 of Fig. 1. For the sake of explanation, Fig. 5 omits the control device 10, the laser optical system 14, the optical system base 81, etc. As shown in Figs. 1 and 5, the laser processing apparatus 1 includes the control device 10, the laser optical system 14, a microscope 20, a Y-axis movement mechanism 30, an X-axis movement mechanism 40, a Z-axis movement mechanism 50, a rotation mechanism 60, vibration suppression mechanisms 71A, 71B, 71C, and 71D, a base 80, and an optical system base 81. The laser processing apparatus 1 is installed on a stand 90.

[0024] Under the control of the control device 10, the stage ST moves along the X, Y, and Z directions and rotates around the Z axis by a Y-axis movement mechanism 30, an X-axis movement mechanism 40, a Z-axis movement mechanism 50, and a rotation mechanism 60. The Y-axis movement mechanism 30, the X-axis movement mechanism 40, the Z-axis movement mechanism 50, and the rotation mechanism 60 are an example of a movement mechanism 100 that moves the stage ST relatively.

[0025] The first laser light source 12A emits a first laser light LA, which is a pulsed laser light having conditions (such as the wavelength, pulse width, and repetition frequency of the laser light) suitable for edge cutting processing, to the laser optical system 14. The second laser light source 12B emits a second laser light LB, which is a pulsed laser light having conditions (such as the wavelength, pulse width, and repetition frequency of the laser light) suitable for center cutting processing, to the laser optical system 14.

[0026] The laser optical system 14 forms two first processing laser beams LA1 for edge cutting based on the first laser beam LA from the first laser light source 12A. The laser optical system 14 also forms one or more second processing laser beams LB1 for center cutting based on the second laser beam LB from the second laser light source 12B. The laser optical system 14 then emits (irradiates) the two first processing laser beams LA1 from the first condenser lens 16 toward the street S. The laser optical system 14 also selectively emits (irradiates) the second processing laser beam LB1 from the second condenser lenses 18A and 18B toward the street S under the control of the control device 10. The laser optical system 14 may be moved in the Y and Z directions by an optical system moving mechanism (not shown) under the control of the control device 10.

[0027] The microscope 20 is fixed to the laser optical system 14 and moves integrally with the laser optical system 14. The microscope 20 photographs an alignment reference (not shown) formed on the wafer W1 before the edge cutting and hollowing processes. The microscope 20 also photographs the two first grooves G1 and second grooves G2 formed along the street S by the edge cutting and hollowing processes. The photographed image (image data) taken by the microscope 20 is output to the control device 10, and is displayed by the control device 10 on a monitor (not shown).

[0028] Here, the moving mechanism 100 includes a Y-axis moving mechanism 30, an X-axis moving mechanism 40, a Z-axis moving mechanism 50, and a rotation mechanism 60, and moves the stage ST in the X, Y, and Z directions and rotates it about a rotation axis under the control of the control device 10. This allows the moving mechanism 100 to move the laser optical system 14 relative to the stage ST and the wafer W1. Note that the method of relative movement is not particularly limited as long as the laser optical system 14 can be moved relative to the stage ST (wafer W1) in each direction (including rotation).

[0029] By relatively moving the stage ST using the movement mechanism 100, it is possible to align the laser optical system 14 with the processing start end, which is one end of the street S to be processed, and to relatively move the laser optical system 14 in the X direction (the outgoing direction X1 side or the returning direction X2 side) along the street S. In addition, by driving the movement mechanism 100 and rotating the stage ST by 90°, it is possible to make each street S along the Y direction of the wafer W1 parallel to the X direction, which is the processing feed direction.

[0030] Y-axis movement mechanism 30 is disposed on base 80. Y-axis movement mechanism 30 includes Y-axis motor 31, Y-axis ball screw 32, two Y-axis rails 33 disposed in parallel on base 80, a Y-axis guide (not shown) disposed on Y-axis rails 33, and a Y-axis table 34 placed on the Y-axis guide. Y-axis table 34 moves linearly in the Y-axis direction along Y-axis rails 33 by Y-axis ball screw 32 driven by Y-axis motor 31 under the control of control device 10.

[0031] The X-axis movement mechanism 40 is disposed on the Y-axis table 34. The X-axis movement mechanism 40 includes an X-axis motor 41, an X-axis ball screw 42, two X-axis rails 43 that are perpendicular to the Y-axis rails 33 and disposed parallel to the Y-axis table 34, an X-axis guide (not shown) disposed on the X-axis rails 43, and an X-axis table 44 placed on the X-axis guide. The X-axis table 44 moves linearly in the X-axis direction along the X-axis rails 43 by the X-axis ball screw 42 driven by the X-axis motor 41 under the control of the control device 10.

[0032] A Z-axis movement mechanism 50 is disposed on X-axis table 44. Z-axis movement mechanism 50 includes a motor (not shown), a Z-axis ball screw (not shown), a Z-axis base (not shown) that is provided perpendicular to X-axis table 44, a Z-axis rail (not shown) that is provided on the Z-axis base, a Z-axis guide that is attached to the Z-axis rail, and a Z-axis table (not shown) that is provided on the Z-axis guide so as to be movable in the Z-axis direction along the Z-axis rail. The Z-axis table moves in the Z-axis direction along the Z-axis rail by a Z-axis ball screw that is driven by the Z-axis motor under the control of control device 10.

[0033] A rotation mechanism 60 is disposed on the Z-axis table. The rotation mechanism 60 rotates the stage ST, which is a support table used to rotate the wafer W1, around the θ-axis. The rotation mechanism 60 is, for example, a motor (not shown) and a shaft (not shown) that is rotated by the motor. Here, the θ-axis is a rotation axis that is oriented in a direction parallel to the Z-axis.

[0034] Vibration suppression mechanism 71A and vibration suppression mechanism 71C are disposed on base 80. Vibration suppression mechanism 71A and vibration suppression mechanism 71C are disposed, for example, parallel to the Y-axis, sandwiching Y-ball screw 32. By disposing vibration suppression mechanism 71A and vibration suppression mechanism 71C in this manner, it is possible to suppress the generation of rotational moment. Furthermore, in order to suppress the generation of rotational moment, it is preferable to dispose them at the same height as Y-ball screw 42.

[0035] The vibration suppression mechanism 71A includes a counterweight 72A, a guide mechanism 73A, a motor 74A, and a ball screw 75A driven by the motor 74A to move the counterweight 72A along the guide mechanism 73A. The counterweights 72A, 72B, 72C, and 72D are movable in the same direction as the workpiece. In this embodiment, the counterweights 72A and 72C are movable in the Y direction, and the counterweights 72B and 72D, which will be described later, are movable in the X direction. The vibration suppression mechanism 71C includes a counterweight 72C, a guide mechanism 73C, a motor 74C, and a ball screw 75C that is driven by the motor 74C and moves the counterweight 72C along the guide mechanism 73C. Counterweights 72A and 72C have a mass necessary to cancel out vibrations generated by the operation of Y-axis moving mechanism 30 and X-axis moving mechanism 40. For example, when counterweights 72A and 72C are to perform the same operation as stage ST, the mass of counterweights 72A and 72C will be approximately the same as the mass of the stage (including the movable parts of the axes to be damped).

[0036] The control device 10 controls the vibration suppression mechanisms 71A and 71C based on the measurement results of the first and second sensing means (described later) to suppress vibrations associated with the movement of the stage ST. When the movement mechanism 100 moves the stage ST in the +Y direction and vibrations reach a predetermined level, the control device 10 suppresses the vibrations by, for example, moving the counterweights 72A and 72C in the -Y direction. Here, "the vibrations reach a predetermined level" refers to, for example, when the positional or angular deviation exceeds a threshold. Specifically, the control device 10 drives the motors 74A and 74C based on the measurement results of the first and second sensing means to move the counterweights 72A and 72C in the Y-axis direction to suppress the vibrations. This reduces the deviation of the laser beam. The motors 74A and 74C, the ball screw 75A, and the motors 74C and 75C are examples of drivers for driving the counterweights. The vibration suppression mechanisms 71A and 71C can operate in two ways: one is to measure the vibration (shift in the position of the laser light) using the first sensing means and the second sensing means described below, and then move the mechanism; the other is to predict the subsequent vibration from the measurement results and then operate the mechanism.

[0037] As a method for predicting and operating, for example, the following method is available. The stage ST is moved under predetermined conditions in advance and vibrations are measured. If the movement of the stage ST is under conditions that will cause vibrations, vibration suppression is activated before the vibrations are detected. Sensing means is used to detect vibrations and confirm whether the vibrations have actually been suppressed.

[0038] Vibration suppression mechanism 71B and vibration suppression mechanism 71D are disposed on base 80. Vibration suppression mechanism 71B and vibration suppression mechanism 71D are disposed, for example, parallel to the X-axis and sandwiching X-axis ball screw 42. By disposing vibration suppression mechanism 71B and vibration suppression mechanism 71D in this manner, it is possible to suppress the generation of rotational moment. The vibration suppression mechanism 71B includes a counterweight 72B, a guide mechanism 73B, a motor 74B, and a ball screw 75B that is driven by the motor 74B and moves the counterweight 72B along the guide mechanism 73B. The vibration suppression mechanism 71D includes a counterweight 72D, a guide mechanism 73D, a motor 74D, and a ball screw 75D that is driven by the motor 74D and moves the counterweight 72D along the guide mechanism 73D. Counterweights 72B and 72D have masses necessary to cancel out vibrations generated by Y-axis moving mechanism 30 and X-axis moving mechanism 40. For example, when counterweights 72B and 72D are to perform the same operation as stage ST, the masses of counterweights 72B and 72D are approximately the same as the mass of the stage (including the movable parts of the axes to be damped).

[0039] The control device 10 controls the vibration suppression mechanisms 71B and 71D based on the measurement results (positional and angular deviations of the laser beam) of the first and second sensing means described below to suppress vibrations caused by movement of the stage ST. If vibrations reach a predetermined level when the stage ST is moved in the +X direction by the movement mechanism 100, the vibrations are suppressed, for example, by moving the counterweights 72B and 72D in the -X direction. Specifically, the control device 10 drives the motors 74B and 74D based on the measurement results of the first and second sensing means to move the counterweights in the X-axis direction to suppress vibrations. This reduces the deviation of the laser beam. The motor 74B and ball screw 75B and the motor 74D and ball screw 75D are examples of drivers that drive the counterweights. The vibration suppression mechanisms 71B and 71D can operate in two ways: one is to measure the vibration (shift in the position of the laser light) using the first sensing means and the second sensing means described below, and then move the mechanism; the other is to predict the subsequent vibration from the measurement results and then operate the mechanism.

[0040] The control device 10 is configured, for example, by a personal computer and includes various processors (for example, a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit)), a memory, and a storage device. The various functions of the control device 10 may be realized by a single processor, or by multiple processors of the same or different types. For example, the control device 10 may be configured by a host device such as a personal computer (PC), a control device (motor driver, sequencer, controller, etc.) for the movement mechanism 100, and control devices (motor driver, sequencer, controller, etc.) for the vibration suppression mechanisms 71A, 71B, 71C, and 71D. The control device 10 comprehensively controls the operations of the first laser light source 12A, the second laser light source 12B, the laser optical system 14, the movement mechanism 100, and the vibration suppression mechanisms 71A, 71B, 71C, and 71D.

[0041] [Laser optics] Next, an example of the laser optical system 14 will be described with reference to FIG. 6. FIG. 6 is a block diagram showing an example of the laser optical system. The first condenser lens 16 in FIG. 1 is disposed between the second condenser lens 18A and the second condenser lens 18B. In other words, the second condenser lenses 18A and 18B are disposed so as to sandwich the first condenser lens 16 therebetween. The second condenser lens 18A is disposed on the backward direction X2 side of the first condenser lens 16. The second condenser lens 18B is disposed on the forward direction X1 side of the first condenser lens 16. The state of the second laser light LB on the second condenser lens 18A side and the second condenser lens 18B side is the same, and in the following description, the second condenser lenses 18A and 18B will be described as the second condenser lens 18.

[0042] The laser optical system 14 includes a first laser light source 12A that emits a first laser beam LA, a first sensing means SSA that measures positional deviation of at least one of the first laser beam LA and the first processing laser beam LA1 due to vibrations generated by the operation of the moving mechanism 100, a first light forming element 22A that forms two first processing laser beams LA1 from the first laser beam LA, a first focusing lens 16 that focuses the first processing laser beam LA1 on the workpiece, a second laser light source 12B that emits a second laser beam, a second sensing means SSB that measures positional deviation of at least one of the second laser beam LB and the second processing laser beam LB1 due to vibrations generated by the operation of the moving mechanism 100, a second light forming element 22B that forms one or more second processing laser beams LB1 from the second laser beam LB, and a second focusing lens 18 that focuses the second processing laser beam LB1 on the workpiece. The first laser light source 12A and the second laser light source 12B are examples of laser light sources. The first light forming element 22A and the second light forming element 22B are examples of light forming elements. The first condenser lens 16 and the second condenser lens 18 are examples of condenser lenses. The first sensing means SSA and the second sensing means SSB are examples of sensing means that detect vibrations. In this embodiment, the first optical system includes the first laser light source 12A that emits the first laser light LA, the first sensing means SSA that measures the positional deviation of at least one of the first laser light LA ​​and the first processing laser light LA1 due to vibrations generated by the movement mechanism 100, the first light forming element 22A that forms two first processing laser lights LA1 from the first laser light LA, and the first focusing lens 16 that focuses the first processing laser light LA1 on the workpiece. The second optical system includes the second laser light source 12B that emits the second laser light, the second sensing means SSB that measures the positional deviation of at least one of the second laser light LB and the second processing laser light LB1 due to vibrations generated by the movement mechanism 100, the second light forming element 22B that forms one or more second processing laser lights LB1 from the second laser light LB, and the second focusing lens 18 that focuses the second processing laser light LB1 on the workpiece. That is, the laser optical system 14 includes two optical systems. The first sensing means SSA and the second sensing means SSB measure the deviation of the first optical system and the deviation of the second optical system, respectively.

[0043] The first sensing means SSA includes a first sensor unit SAU and a second sensor unit SA1U. The first sensor unit SAU is disposed on the optical path between the first laser light source 12A and the first light forming element 22A. The first sensor unit SAU includes a first mirror MAa that reflects the first laser light LA, and a first sensor SA that measures the deviation of the first laser light LA ​​that has passed through the first mirror MAa. The first mirror MAa is an example of a mirror. The first sensor SA is an example of a sensor. The second sensor unit SA1U is disposed on the optical path between the first light forming element 22A and the first condenser lens 16. The second sensor unit SA1U includes a second mirror MA1a that reflects the first processing laser beam LA1 and a second sensor SA1 that measures the deviation of the first processing laser beam LA1 that has passed through the second mirror MA1a. The second mirror MA1a is an example of a mirror. The second sensor SA1 is an example of a sensor.

[0044] The second sensing means SSB includes a third sensor unit SBU and a fourth sensor unit SB1U. The third sensor unit SBU is disposed on the optical path between the second laser light source 12B and the second light forming element 22B. The third sensor unit SBU includes a third mirror MBa that reflects the second laser light LB, and a third sensor SB that measures the deviation of the transmitted light LBT of the second laser light that has passed through the third mirror MBa. The third mirror MBa is an example of a mirror. The third sensor SB is an example of a sensor. The fourth sensor unit SB1U is disposed on the optical path between the second light forming element 22B and the second condenser lens 18. The fourth sensor unit SB1U includes a fourth mirror MB1a that reflects the second processing laser beam LB1 and a fourth sensor SB1 that measures the deviation of the transmitted light LB1T of the second processing laser beam that has passed through the fourth mirror MB1a. The fourth mirror MB1a is an example of a mirror. The fourth sensor SB1 is an example of a sensor.

[0045] The first mirror MAa is disposed on the optical path between the first laser light source 12A and the mirror MAb. The first mirror MAa reflects the first laser light LA ​​incident from the first laser light source 12A toward the mirror MAb. When the first laser light LA ​​is reflected by the first mirror MAa, a small amount of transmitted light LAT is generated behind the first mirror MAa. This transmitted light LAT of the first laser light LA ​​is incident on the first sensor SA.

[0046] The first sensor SA measures the deviation of the position of the first laser beam LA caused by vibrations generated by the operation of the moving mechanism 100. The first sensor SA is, for example, a position sensor detector (PSD, position detection sensor). This makes it possible to detect the deviation of the position of the first laser beam LA caused by vibrations generated by the operation of the moving mechanism 100. The measured deviation of the position of the first laser beam LA is sent to the control device 10.

[0047] The mirror MAb is disposed on the optical path between the first mirror MAa and the first light forming element 22 A. The mirror MAb reflects the first laser beam LA reflected by the first mirror MAa toward the first light forming element 22 A.

[0048] The first light forming element 22A is disposed on the optical path between the mirror MAb and the mirror MA1b. The first light forming element 22A forms two first processing laser beams LA1 from the incident first laser beam LA and emits them toward the mirror MA1b. As a result, the two first processing laser beams LA1 are focused on the street S (on the outward and return paths) by the first focusing lens 16, and two spots (also referred to as focused points or processing points) spaced apart in the Y direction are formed on the street S.

[0049] The first light forming element 22A may be, for example, a diffractive optical element, a refractive optical element, a prism, or a combination thereof. A diffractive optical element (DOE) may also be used as the first light forming element 22A. The optical paths of the two first processing laser beams LA1 from the first light forming element 22A to the first condenser lens 16 are omitted from the illustration.

[0050] The mirror MA1b is disposed on the optical path between the second mirror MA1a and the first light forming element 22A. The mirror MA1b reflects the two first processing laser beams LA1 incident from the first light forming element 22A to the second mirror MA1a.

[0051] The second mirror MA1a is disposed on the optical path between the first focusing lens 16 and the mirror MA1b. The second mirror MA1a reflects the first processing laser beam LA1 toward the first focusing lens 16. When the second mirror MA1a reflects the first processing laser beam LA1, a small amount of transmitted light LA1T is generated behind the second mirror MA1a. This transmitted light LA1T of the first processing laser beam LA1 is incident on the second sensor SA1.

[0052] The second sensor SA1 measures the positional deviation of the first processing laser beam LA1 due to vibrations generated by the operation of the moving mechanism 100. The second sensor SA1 is, for example, a position sensor detector. This allows the positional deviation of the first processing laser beam LA1 due to vibrations generated by the operation of the moving mechanism 100 to be detected. The measured positional deviation of the first processing laser beam LA1 is sent to the control device 10. The control device 10 can also calculate the angular deviation of the first processing laser beam LA1 using the following equation (1) based on the positional deviations measured by the first sensor SA and the second sensor SA1. In the following equation (1), θ represents the angular deviation, B represents the amount of positional deviation, and A represents the optical path length. For example, as shown in FIG. 7, it is preferable to arrange the first laser light source 12A and the first sensor SA so that the optical path length between the first sensor SA and the second sensor SA1 is equal to the optical path length between the first sensor SA and the second sensor SA1. By using the first sensor SA and the second sensor SA1, the angular deviation θ can be measured from the deviation amount B measured by the first sensor SA and the deviation amount B′ measured by the second sensor SA1. B = A × tanθ (1)

[0053] The third mirror MBa is disposed on the optical path between the second laser light source 12B and the mirror MBb. The third mirror MBa reflects the second laser light LB incident from the second laser light source 12B toward the mirror MBb. When the second laser light LB is reflected by the third mirror MBa, a small amount of transmitted light LBT is generated behind the third mirror MBa. This transmitted light LBT of the second laser light LB is incident on the third sensor SB.

[0054] The third sensor SB measures the deviation in the position of the second laser beam LB caused by vibrations generated by the operation of the moving mechanism 100. The third sensor SB is, for example, a position sensor detector. This makes it possible to detect the deviation in the position of the second laser beam LB caused by vibrations generated by the operation of the moving mechanism 100. The measured deviation in the position of the second laser beam LB is sent to the control device 10.

[0055] The mirror MBb is disposed on the optical path between the third mirror MBa and the second light forming element 22B. The mirror MBb reflects the second laser light LB reflected by the third mirror MBa toward the second light forming element 22B.

[0056] The second light forming element 22B is disposed on the optical path between the mirrors MBb and MB1b. The second light forming element 22B forms a second processing laser beam LB1 corresponding to one or more hollowing processes from the incident second laser beam LB and emits it toward the mirror MB1b. As a result, the second processing laser beam LB1 forms one or more rectangular (or other shapes such as circular) spots between the two edge-cutting grooves G1 on the wafer W1, which is the workpiece. The width of this spot in the Y direction is adjusted to match the spacing between the two edge-cutting grooves G1. Note that when there are multiple spots, the spots of the second processing laser beam LB1 are spaced apart in the X direction.

[0057] The second light forming element 22B may be, for example, a mask, a diffractive optical element, a refractive optical element, a prism, or a combination thereof. When two or more second processing laser beams are formed, a diffractive optical element (DOE) may be used as the second light forming element 22B. Note that the following description will be given taking as an example a case where one second processing laser beam LB1 is formed from the second light forming element 22B.

[0058] The mirror MB1b is disposed on the optical path between the fourth mirror MB1a and the second light forming element 22B. The mirror MB1b reflects one or more second processing laser beams LB1 incident from the second light forming element 22B to the fourth mirror MB1a.

[0059] The fourth mirror MB1a is disposed on the optical path between the second focusing lens 18 and the mirror MB1b. The fourth mirror MB1a reflects the second processing laser beam LB1 toward the second focusing lens 18. When the second processing laser beam LB1 is reflected by the fourth mirror MB1a, a small amount of transmitted light LB1T is generated behind the fourth mirror MB1a. This transmitted light LB1T of the second processing laser beam LB1 is incident on the fourth sensor SB1.

[0060] The fourth sensor SB1 measures the positional deviation of the second processing laser beam LB1 due to vibrations generated by the operation of the moving mechanism 100. The fourth sensor SB1 is, for example, a position sensor detector. This allows the positional deviation of the second processing laser beam LB1 due to vibrations generated by the operation of the moving mechanism 100 to be detected. The measured positional deviation of the second processing laser beam LB1 is sent to the control device 10. The control device 10 can also calculate the angular deviation of the second processing laser beam LB1 using the above equation (1) based on the positional deviations measured by the third sensor SB and the fourth sensor SB1. For example, by arranging the optical path lengths between the second laser light source 12B and the third sensor SB and the third sensor SB1 so that they are equal, the angular deviation can be measured from the deviation amount measured by the third sensor SB and the deviation amount measured by the fourth sensor SB1.

[0061] The second focusing lens 18 focuses the incident second processing laser LB1 onto the wafer W1, which is the workpiece, thereby forming one or more spots (also referred to as focusing points or processing points) on the street S.

[0062] The above has described the laser processing device 1 according to this embodiment. The laser processing device 1 can suppress deviations between the laser beams due to vibrations.

[0063] The drive unit of the vibration suppression mechanism in this embodiment is a motor and ball screw, but it may also be a belt and motor or a linear motor. Instead of the drive unit, the X-axis or Y-axis to be damped and the counterweight may be connected by a rack and pinion, or by a pulley and belt.

[0064] In the laser processing apparatus 1, the vibration suppression mechanism 71B and the vibration suppression mechanism 71D are arranged parallel to the X-axis on the base 80, and the vibration suppression mechanism 71B and the vibration suppression mechanism 71D are arranged parallel to the X-axis on the base 80, but the vibration suppression mechanism 71B and the vibration suppression mechanism 71D may also be arranged parallel to the X-axis on the Y-axis table 34. Only vibration suppressing mechanisms 71B and 71D may be arranged on Y-axis table 34 in parallel with the X-axis.

[0065] In the laser processing apparatus 1, vibration suppression mechanisms 71A and 71C are arranged parallel to the Y-axis on the base 80, and vibration suppression mechanisms 71B and 71D are arranged parallel to the X-axis on the base 80, but only vibration suppression mechanisms 71A and 71C may be arranged parallel to the Y-axis on the base 80, or only vibration suppression mechanisms 71B and 71D may be arranged parallel to the X-axis on the base 80.

[0066] The guide mechanisms of the vibration suppression mechanisms 71A, 71B, 71C, and 71D of this embodiment include, for example, linear guides, air bearings, linear bushings, etc. It is preferable to use two axes, but one axis is also acceptable.

[0067] In this embodiment, the first sensor unit SAU, the third sensor unit SBU, the second sensor unit SA1U, and the fourth sensor unit SB1U are each composed of a reflecting mirror and a sensor for measuring positional deviation. However, a lens may be placed on the optical path between the reflecting mirror and the sensor. The distance between the lens and the sensor is preferably the focal length of the lens. In this case, the angular deviation can be calculated using the following two equations: f in equation (2) is the focal length of the lens, B is the deviation of the laser beam, and θ is the angular deviation of the laser beam. The shift of the laser beam entering the lens is not reflected in the deviation of the focal point, but the angle is converted into a deviation corresponding to the focal length of the lens. This makes it possible to detect only the angular component. When angular deviation occurs, the irradiation position on the workpiece changes when the laser enters the focusing lens. When positional deviation occurs, the irradiation position does not change when the laser enters the focusing lens, but the shape formed by light-generating elements such as diffractive optical elements is affected by the positional deviation. Therefore, it is important to measure both angular and positional deviations. B = f × tanθ (2)

[0068] Although four sensor units (first sensor unit SAU, third sensor unit SBU, second sensor unit SA1U, and fourth sensor unit SB1U) are arranged on the optical path, the number of sensor units is not limited to this number. For example, only the first sensor unit SAU and the third sensor unit SBU may be arranged. In this case, the first sensor unit SAU may be arranged at the position of the second sensor unit SA1U, and the third sensor unit SBU may be arranged at the position of the fourth sensor unit SB1U. Furthermore, five or more sensor units may be arranged.

[0069] The first sensor SA, the third sensor SB, the second sensor SA1, and the fourth sensor SB1 may all be cameras, or the first sensor SA, the second sensor SA1, the third sensor SB, and the fourth sensor SB1 may all be position detective sensors, or a combination of cameras and position detective sensors may be used as the first sensor SA, the second sensor SA1, the third sensor SB, and the fourth sensor SB1.

[0070] In this embodiment, first laser light source 12A and second laser light source 12B are used and deviation in the position of the laser light is detected by each of them, but vibration may be suppressed by detecting deviation in only one of first laser light source 12A and second laser light source 12B. That is, vibration suppression mechanisms 71A, 71B, 71C, and 71D may suppress vibration based on the measurement results of at least one of first sensing means SSA and second sensing means SSB.

[0071] [Laser processing method] Next, a laser processing method using the laser processing device 1 according to this embodiment will be described. FIG. 8 is a flowchart of the laser processing method according to this embodiment. Here, a method for processing one street S will be described as an example. Laser processing can be performed in the same manner until processing of all streets S is completed. In processing the street S, first, the emission position (spot) of the laser light is adjusted, and then the first laser light source 12A and the second laser light source 12B start emitting the first laser light LA ​​and the second laser light LB (step S1). Next, measurement of the deviations (positional deviation and angular deviation) of the laser light by the first sensor unit SAU, the third sensor unit SBU, the second sensor unit SA1U, and the fourth sensor unit SB1U starts (step S2). The control device 10 records the values ​​in the stationary state before the stage ST is moved by the moving mechanism 100 as initial values. Next, the moving mechanism 100 starts moving the stage ST along the street S (step S3). During the movement of the stage ST, it is determined whether the deviation of the laser beam due to vibration measured by the first sensor unit SAU, the third sensor unit SBU, the second sensor unit SA1U, and the fourth sensor unit SB1U exceeds a threshold (step S4). If the deviation of the laser beam due to vibration is less than the threshold, the vibration suppression mechanisms 71A, 71B, 71C, and 71D are not activated, and the movement of the stage ST continues (step S4: YES). If the deviation is equal to or greater than the threshold (step S4: NO), the vibration suppression mechanisms 71A, 71B, 71C, and 71D are activated to suppress vibrations generated by the operation of the moving mechanism 100 (step S5). This reduces the deviation of the laser beam. If the processing of the planned processing area (street S) is completed (step S6: YES), the laser processing ends. If the processing of the planned processing area is not completed (step S6: NO), the moving mechanism 100 continues moving the stage ST (step S3).

[0072] (Vibration suppression method) Next, the vibration suppression in step S5 will be described. The vibration suppression mechanisms 71A, 71B, 71C, and 71D operate by measuring the waveform of the deviation of the laser beam to be measured. FIG. 9(a) shows an example of the waveform of the deviation of the laser beam measured by the first sensor SA, etc. FIG. 9(b) shows an example of the waveform of the deviation of the laser beam measured by the first sensor SA, etc. after vibration suppression. The vertical axis of FIG. 9(a) represents the deviation amount (amount of displacement), and the horizontal axis represents the elapsed time. The vibration suppression mechanisms 71A, 71B, 71C, and 71D operate based on the measurement result of the waveform of the deviation of the laser beam to be measured, so that the vibration suppression mechanisms 71A, 71B, 71C, and 71D are operated to have the opposite phase to the waveform. This allows the deviation of the laser beam to be reduced, as shown in FIG. 9(b).

[0073] (Laser processing device variation 1) Next, a laser processing apparatus 1A, which is a first modified example of the laser processing apparatus, will be described with reference to FIGS. 10 and 11. FIG. 10 is a perspective view of the laser processing apparatus 1A. FIG. 11 is a plan view of the laser processing apparatus 1A of FIG. 10. For ease of explanation, FIG. 11 omits the control device 10, the laser optical system 14, the optical system base 81, and other components. As shown in FIGS. 9 and 10, the laser processing apparatus 1 includes the control device 10, the laser optical system 14, the microscope 20, the Y-axis movement mechanism 30, the X-axis movement mechanism 40, the Z-axis movement mechanism 50, the rotation mechanism 60, the vibration suppression mechanisms 76A, 76B, 76C, and 76D, a base 80 on which the movement mechanism 100 is mounted, and the optical system base 81. The laser processing apparatus 1 is installed on a stand 90. In the following description, components identical to those in the laser processing apparatus 1 are denoted by the same reference numerals, and their description will be omitted. Only differences will be described. The laser processing apparatus 1 may include a stand 90. A base 80 is placed on the stand 90. The vibration suppression mechanisms 76A, 76B, 76C, and 76D are actuators that can move the base 80 in the direction opposite to the direction of movement of the wafer W1, which is the workpiece.

[0074] Vibration suppression mechanism 76A and vibration suppression mechanism 76C are disposed between base 80 and mount 90. Vibration suppression mechanism 76A and vibration suppression mechanism 76C are disposed, for example, parallel to the Y axis, sandwiching Y-axis ball screw 32. By disposing vibration suppression mechanism 76A and vibration suppression mechanism 76C in this manner, it is possible to suppress the generation of rotational moment.

[0075] The vibration suppression mechanism 76A is an actuator including a fixed part 77A fixed to the pedestal 90 and a movable part 78A fixed to the base 80 and movable in the Y-axis direction. The actuator is not particularly limited, but may be, for example, a linear motor or a voice coil motor. The fixed part 77A and the movable part 78A may be reversed. That is, the fixed part 77A may be fixed to the base 80, and the movable part 78A may be fixed to the pedestal 90 and movable in the Y-axis direction. The vibration suppression mechanism 76C is an actuator including a fixed part 77C fixed to the pedestal 90 and a movable part 78C fixed to the base 80 and movable in the Y-axis direction. The fixed part 77C and the movable part 78C may be reversed. That is, the fixed part 77C may be fixed to the base 80, and the movable part 78C may be fixed to the pedestal 90 and movable in the Y-axis direction.

[0076] Control device 10 controls vibration suppression mechanisms 76A and 76C based on the measurement results of first sensing means and second sensing means (described later) to suppress vibrations caused by movement of stage ST, etc. Specifically, based on the measurement results of first sensing means SSA and second sensing means SSB, vibration suppression mechanisms 76A and 76C apply to base 80 a reaction force to the force generated when moving mechanism 100 is operated. Vibration suppression mechanisms 76A and 76C can be operated in two ways: one in which they measure vibrations (deviations in the position of the laser light) using first sensing means SSA and second sensing means SSB and then move, and the other in which they predict subsequent vibrations from the measurement results and then operate.

[0077] Vibration suppression mechanisms 76B and 76D are disposed between base 80 and mount 90. Vibration suppression mechanisms 76B and 76D are disposed, for example, parallel to the X-axis, sandwiching X-axis ball screw 42. By disposing vibration suppression mechanisms 76B and 76D in this manner, it is possible to suppress the generation of rotational moment.

[0078] Vibration suppression mechanism 76B is an actuator including a fixed part 77B fixed to mount 90 and a movable part 78B fixed to base 80 and movable in the X-axis direction. Fixed part 77B and movable part 78B may be reversed. That is, fixed part 77B may be fixed to base 80, and movable part 78B may be fixed to mount 90 and movable in the X-axis direction. Vibration suppression mechanism 76D is an actuator including a fixed part 77D fixed to mount 90 and a movable part 78D fixed to base 80 and movable in the X-axis direction. Fixed part 77D and movable part 78D may be reversed. That is, fixed part 77D may be fixed to base 80, and movable part 78D may be fixed to mount 90 and movable in the Y-axis direction.

[0079] The control device 10 controls the vibration suppression mechanisms 76B and 76D based on the measurement results (positional and angular deviations of the laser beam) of the first sensing means SSA and the second sensing means SSB described below to suppress vibrations caused by movement of the stage ST. Specifically, based on the measurement results of the first sensing means SSA and the second sensing means SSB, the vibration suppression mechanisms 76B and 76D apply a reaction force to the base 80 against the force generated when the movement mechanism 100 is operated. This reduces deviations of the laser beam. The vibration suppression mechanisms 76B and 76D can be operated in two ways: one in which the first sensing means SSA and the second sensing means SSB measure vibrations (positional deviations of the laser beam) and then move, and the other in which subsequent vibrations are predicted from the measurement results and then operated.

[0080] The laser processing apparatus 1A according to this embodiment has been described above. The laser processing apparatus 1A can suppress deviations between the laser beams due to vibrations.

[0081] In the laser processing apparatus 1A, the vibration suppression mechanisms 76A and 76C are arranged parallel to the Y axis, and the vibration suppression mechanisms 76B and 76D are arranged parallel to the X axis, but it is also possible to arrange only the vibration suppression mechanisms 76A and 76C parallel to the Y axis, and only the vibration suppression mechanisms 76B and 76D parallel to the X axis.

[0082] The technical scope of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. In addition, the components in the above-described embodiments can be replaced with well-known components as appropriate, and the above-described modifications can be combined as appropriate, without departing from the spirit of the present invention. [Explanation of symbols]

[0083] 1 laser processing device, 10 control device, 12A first laser light source, 12B second laser light source, 30 Y-axis movement mechanism 30, 40 X-axis movement mechanism, 50 Z-axis movement mechanism, 60 rotation mechanism, 100 movement mechanism

Claims

1. a laser light source that emits laser light; a light forming element that forms a processed laser beam from the laser beam; a condenser lens that condenses the processing laser light onto a workpiece; an optical system comprising: a moving mechanism for moving the workpiece; a sensing means for detecting vibration; a vibration suppression mechanism that suppresses the vibration based on the measurement result of the sensing means; A laser processing device comprising:

2. Two of the optical systems are provided, 2. The laser processing device according to claim 1, wherein the optical system is provided with the sensing means for measuring a deviation of the optical system.

3. 3. The laser processing device according to claim 1, wherein the vibration suppression mechanism includes a counterweight that is movable in the same direction as the workpiece.

4. a base on which the moving mechanism is mounted; a stand on which the base is mounted; 3. The laser processing device according to claim 1, further comprising: an actuator capable of moving the base in a direction opposite to a moving direction of the workpiece.

5. 3. The laser processing device according to claim 2, wherein said sensing means measures a positional deviation of at least one of said laser beam and said processing laser beam caused by said vibrations generated by the operation of said moving mechanism.

6. 3. The laser processing apparatus according to claim 2, wherein the sensing means measures the positional deviation of the laser beam and the processing laser beam caused by the vibration generated by the operation of the moving mechanism, and detects the angular deviation of the laser beam.

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