Laser Processing Equipment

Abstract

To provide a laser processing device that can process a work-piece while measuring (what is called, monitoring) a beam intensity, without causing energy loss of a laser beam for processing.SOLUTION: A laser processing device, which processes a work-piece by emitting a laser beam, comprises: a laser oscillator that emits a laser beam; a beam intensity adjusting part that adjusts an intensity of the laser beam to an intensity of a laser beam to be emitted to the work-piece, by eliminating a portion of the laser beam; and a beam intensity measuring part that measures the beam intensity of the laser beam. The beam intensity measuring part measures a beam intensity of a laser beam for non-processing excluded by the beam intensity adjusting part, and calculates a beam intensity of the laser beam for processing that is emitted to the work-piece, on the basis of the beam intensity.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a laser processing apparatus that processes a workpiece by irradiating it with a laser beam. [Background technology]

[0002] Conventionally, there has been known an apparatus (laser processing apparatus) that irradiates a laser beam focused onto a spot (so-called laser ablation) in order to remove thin films or wiring patterns formed on a substrate, or to mark characters, figures, etc.

[0003] A known technology uses laser ablation technology that uses a laser beam and a galvanometer scanner to peel off elements (chips) arranged on a source substrate (donor substrate) and transfer the peeled off elements to a destination substrate (target substrate) arranged opposite the donor substrate (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2006-41500 A Summary of the Invention [Problem to be solved by the invention]

[0005] In laser processing, in order to maintain and manage the processing quality of the workpiece, it is important to check that the beam intensity of the laser beam during processing is within a specified range. In addition, if the beam intensity deviates from the specified range or is about to deviate, it must be detected and corrected early.

[0006] Conventionally, a portion of the laser beam used for processing that is irradiated onto the workpiece is branched off to measure the beam intensity, resulting in energy loss.

[0007] Therefore, the present invention has been made in consideration of the above problems, An object of the present invention is to provide a laser processing device capable of processing while measuring (so-called monitoring) the beam intensity without causing energy loss in the processing laser beam. [Means for solving the problem]

[0008] In order to solve the above problems, one aspect of the present invention is to A laser processing device that processes a workpiece by irradiating a laser beam, a laser oscillator that emits a laser beam; a beam intensity adjusting unit that adjusts the laser beam to a beam intensity for irradiating a workpiece by removing a portion of the laser beam; a beam intensity measuring unit that measures the beam intensity of the laser beam, the beam intensity adjusting unit includes a beam branching unit that branches the processing laser beam and the non-processing laser beam at an arbitrary beam intensity ratio; The beam intensity measurement section is The beam intensity of the non-processing laser beam rejected by the beam intensity adjusting unit is measured, and the beam intensity Calculating the beam intensity of the processing laser beam to be irradiated onto the workpiece based on the beam intensity ratio; The beam intensity adjusting section adjusts the beam intensity ratio based on the beam intensity of the non-processing laser beam measured by the beam intensity measuring section and the previously grasped transient characteristics of the beam intensity of the laser beam emitted from the laser oscillator. The laser processing device is characterized by the above.

[0009] According to this aspect, Since the beam intensity can be measured by the non-processing laser beam rejected by the beam intensity adjusting section, it is not necessary to branch off a part of the processing laser beam for monitoring. Effect of the Invention

[0010] Processing can be performed while measuring (monitoring) the beam intensity without causing any loss of energy in the processing laser beam. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing an overall configuration of an example of an embodiment of the present invention; [Diagram 2] 4 is a graph showing the change characteristics of the beam intensity and the like over time of a laser beam in an example of an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following explanation, the three axes of the Cartesian coordinate system are designated as X, Y, and Z, the horizontal direction is expressed as the X direction and the Y direction, and the direction perpendicular to the XY plane (i.e., the direction of gravity) is expressed as the Z direction. The direction against gravity in the Z direction is expressed as up, and the direction in which gravity acts is expressed as down. The direction of rotation around the Z direction as the central axis is called the θ direction. The X direction may also be expressed as horizontal, the Y direction as vertical, and the XY directions as vertical and horizontal.

[0013] Fig. 1 is a schematic diagram showing the overall configuration of an example of an embodiment of the present invention, showing a laser processing device 1 according to the present invention.

[0014] The laser processing device 1 according to the present invention irradiates a processing laser beam B1 to process a workpiece W. In this example, a wafer-shaped, approximately circular substrate is exemplified as the workpiece W, thin films are formed in layers on the surface of the substrate, and a configuration is exemplified in which the topmost thin film is selectively removed in a predetermined pattern. Specifically, the laser processing apparatus 1 includes a laser oscillator 2, a beam intensity adjusting section 3, a beam intensity measuring section 4, and a control section CN. The laser processing apparatus 1 further includes a substrate holding section H, a relative moving section M, and the like.

[0015] The laser oscillator 2 emits a laser beam B0. Specifically, the laser oscillator 2 is configured to emit a pulsed laser beam B0 with an energy density sufficient for processing the workpiece W in response to a trigger signal Vt output from the control unit CN. More specifically, the laser oscillator 2 can be, for example, a green laser (wavelength 532 nm) that emits the second harmonic of a YAG laser (fundamental wavelength 1064 nm) as a laser beam B0.

[0016] The beam intensity adjusting section 3 adjusts the laser beam to a beam intensity for irradiating the workpiece W by removing a portion of the laser beam. Specifically, the beam intensity adjustment unit 3 is disposed in the optical path of the laser beam B0, and emits the energy required for processing as a processing laser beam B1 while eliminating a portion of the energy of the laser beam B0 that is not required for processing the workpiece W. More specifically, the beam intensity adjusting unit 3 includes a beam branching unit 31 .

[0017] The beam splitter 31 splits the laser beam B0 into a processing laser beam B1 that is irradiated onto the workpiece W and a non-processing laser beam Bz that is removed. Specifically, an acousto-optic element 32 is shown as an example of the beam splitter 31 . The acousto-optical element 32 splits the laser beam B0 into a processing laser beam B1 and a non-processing laser beam Bz based on a control signal Vrf input from the control unit CN, and emits them in different directions, while setting the beam intensities Ib, Ibz of these beams B1, Bz to an arbitrary beam intensity ratio PR. The beam intensity ratio PR is defined as the following formula (1).

[0018]

number

[0019] Specifically, when the control signal Vrf is not applied, the acousto-optical element 32 passes the laser beam B0 in a straight line and emits it as zero-order light. When the control signal Vrf is applied, the acousto-optical element 32 splits a part of the laser beam B0, emits first-order light in a direction different from the zero-order light, and emits the remainder as zero-order light. In this example, the laser beam emitted as a first-order light from the acousto-optical element 32 is irradiated toward the workpiece W as a processing laser beam B1, and the laser beam that is excluded (i.e., emitted as a zero-order light) is a non-processing laser beam Bz.

[0020] The beam intensity measuring unit 4 measures the beam intensity of the laser beam. Specifically, the beam intensity measuring unit 4 measures the beam intensity Ibz of the non-processing laser beam Bz rejected by the beam intensity adjusting unit 3, and calculates the beam intensity Ib of the processing laser beam B1 to be irradiated to the workpiece W based on the beam intensity Ibz. More specifically, the beam intensity measurement unit 4 includes a beam intensity measuring device 41, a beam intensity calculation unit 42, a mirror M1, and the like.

[0021] The mirror M1 reflects the non-processing laser beam Bz to change the emission direction of the beam Bz. Specifically, the mirror M1 is disposed at a position and angle such that the non-processing laser beam Bz emitted from the acousto-optical element 32 is incident on the beam intensity measuring device 41.

[0022] The beam intensity measuring device 41 measures the beam intensity Ibz of the non-processing laser beam Bz. Specifically, the beam intensity measuring device 41 is configured to convert the intensity of the received light or energy into an electrical signal (voltage, current, etc.) or a data string proportional to the intensity, and output the signal. More specifically, the beam intensity measuring device 41 can be exemplified by a configuration including photoelectric elements called photodiodes arranged in a matrix.

[0023] The beam intensity calculation section 42 calculates the beam intensity Ib of the processing laser beam B1 based on the beam intensity Ibz of the non-processing laser beam Bz and the beam intensity ratio PR. Specifically, the beam intensity calculation unit 42 is composed of a computer (hardware) and its execution program (software), and inputs an electrical signal etc. (i.e., one indicating the beam intensity Ibz of the non-processing laser beam Bz) output from the beam intensity measuring device 41, and calculates the beam intensity Ib of the processing laser beam B1 using equation (2) based on the beam intensity ratio PR, which is known in advance, of the beam intensity Ibz.

[0024]

number

[0025] The control unit CN controls each part of the laser processing device 1. Furthermore, the control unit CN adjusts the beam intensity ratio PR. Specifically, the control unit CN has the following functions: A trigger signal Vt is sent to the laser oscillator 2 to irradiate the laser beam B0 in a pulsed manner. The voltage Vrf of the RF signal output to the acousto-optical element 32 is controlled (i.e., the beam intensity adjustment unit 3 is controlled) to adjust the beam intensity ratio PR of the processing laser beam B1 and the non-processing laser beam Bz from immediately after the laser beam B0 is emitted until a predetermined time has elapsed. While grasping the current position and angle information of the X-axis slider M1, Y-axis slider M2, rotation mechanism M3, etc., the positions and moving speeds of the X-axis slider M1 and Y-axis slider M2, the angle of the rotation mechanism M3, etc. are controlled (i.e., the irradiation position of the processing laser beam B1 is moved relative to the workpiece W). Based on preregistered processing pattern information, the processing laser beam B1 is sequentially irradiated onto the workpiece W to perform the desired processing (i.e., laser processing).

[0026] More specifically, the control unit CN is composed of a computer, a programmable logic controller, a control controller, etc. (hardware) and its execution program (software), and can control each part via signal input / output means, data communication means, etc.

[0027] The substrate holder H holds the workpiece W. Specifically, the base holder H supports the substantially circular substrate, which is the workpiece W, from the lower surface side while keeping it in a horizontal state. More specifically, the substrate holder H has a mounting table H1 with a horizontal upper surface. The mounting table H1 has grooves and holes in the portion that comes into contact with the workpiece W, and these grooves and holes are connected to negative pressure generating means such as a vacuum pump via a switching valve or the like. The substrate holding portion H can hold or release the workpiece W by switching the grooves and holes of the mounting table H1 to a negative pressure state or an atmospheric open state.

[0028] The relative movement unit M changes the irradiation position of the processing laser beam B1 on the workpiece W. Specifically, the relative movement unit M moves the substrate holding unit H in the horizontal direction (XY direction), and is configured with an X-axis slider M1, a Y-axis slider M2, a rotation mechanism M3, etc.

[0029] The X-axis slider M1 is attached onto the device frame 1f, and moves the Y-axis slider M2 in the X direction at an arbitrary speed and stops it at an arbitrary position. The Y-axis slider M2 moves the rotation mechanism M3 in the Y direction at a given speed and stops it at a given position based on a control signal output from the control unit CN. Specifically, the slider drive units for the X-axis slider M1 and the Y-axis slider M2 may be, for example, a combination of a servo motor or pulse motor and a ball screw mechanism that rotates and stops under signal control from the control unit CN, or a linear motor mechanism. The rotation mechanism M3 rotates the mounting table H1 in the θ direction at a desired speed and stops it at a desired angle. Specifically, the rotation mechanism M3 may be, for example, a direct drive motor or the like that rotates / stops it at a desired angle under signal control from an external device. The mounting table H1 of the substrate holder H is attached to the rotating member of the rotation mechanism M3.

[0030] Since the relative movement section M has such a configuration, it is possible to change the position and angle of the workpiece W while holding it, and to move it relatively to the processing laser beam B1.

[0031] The mirrors M2 and M3 reflect the processing laser beam B1 and adjust the emission direction of the beam B1. Specifically, the mirrors M2 and M3 are disposed at positions and angles such that the processing laser beam B1 emitted from the acousto-optical element 32 is irradiated onto the workpiece W substantially perpendicularly.

[0032] Fig. 2 is a graph showing the change characteristics of the beam intensity etc. over time of a laser beam in one example of an embodiment of the present invention. In Fig. 2(a), the beam intensity of the laser beam B0 emitted from the laser oscillator 2 is shown by a dashed line, and the beam intensity Ib of the processing laser beam B1 calculated (i.e., measured) by applying the present invention is shown by a solid line. Meanwhile, Fig. 2(b) shows the change over time of the beam intensity ratio PR of the processing laser beam B1 and the non-processing laser beam Bz branched by the acousto-optical element 32.

[0033] The laser oscillator 2 shown in this example has an output characteristic in which the beam intensity of the laser beam B0 rises sharply from immediately after the beam emission (time T0) until time T1 has elapsed, the rise becomes somewhat more gradual, reaches a peak, then drops slightly and stabilizes. Therefore, by grasping this transient characteristic in advance, the RF signal Vrf applied to the acousto-optical element 32 is controlled to adjust the beam intensity ratio PR so that the beam intensity Ib of the processing laser beam becomes constant.

[0034] On the other hand, after the time T1 has elapsed, the beam intensity of the laser beam B0 is generally stable, so the beam intensity ratio PR is maintained constant. By doing so, the beam intensity Ib of the processing laser beam can be measured whether the beam intensity ratio PR is being adjusted or maintained constant. If the output of the laser beam B0 suddenly fluctuates, the fluctuation can be grasped.

[0035] For example, even if the output temporarily decreases slightly at time T2 or temporarily increases slightly at time T3, the fluctuation can be grasped by measuring the beam intensity Ibz of the non-processing laser beam Bz, and therefore the beam intensity Ib of the processing laser beam B1 can be calculated (i.e., measured).

[0036] Because the laser processing apparatus 1 of the present invention is configured as described above, it is possible to perform laser processing in a desired pattern while measuring (monitoring) the beam intensity Ib of the processing laser beam B1, which is adjusted to the beam intensity Ib required for processing the workpiece W, without causing any energy loss from the laser beam B0 emitted from the laser oscillator 2.

[0037] [Variations] The above-mentioned laser processing apparatus 1 may be configured such that the beam intensity measuring unit 4 further includes a beam intensity determining unit 43 in addition to the above-mentioned configuration.

[0038] The beam intensity determination section 43 compares the beam intensity Ib of the processing laser beam B1 calculated by the processing beam intensity calculation section 42 with a predefined threshold value. Specifically, the beam intensity determination unit 43 notifies an operator or the like of an alarm (so-called warning) when the beam intensity Ib calculated by the processing beam intensity calculation unit 42 exceeds a threshold value. The threshold value may be set on both the upper limit side and the lower limit side, or on either one side.

[0039] Also, the threshold may be set in multiple stages, not just one for the upper limit and one for the lower limit. For example, a first alarm (so-called a warning) that notifies that the value is slightly out of the appropriate range and a second alarm (so-called a warning) that notifies that the value is significantly out of the appropriate range can be exemplified.

[0040] Such a configuration is preferable because it allows information to be transmitted to operators, maintenance personnel, etc. at an early stage, and allows preparations for maintenance and arrangements for part replacement and repairs to be made promptly.

[0041] The above-mentioned laser processing device 1 may be configured to further include a data logging unit 5 in addition to the above-mentioned configuration.

[0042] The data logging unit 5 logs the beam intensity Ib of the processing laser beam B1 measured by the beam intensity measuring unit 4 together with the time. Specifically, the data logging unit 5 is composed of a computer storage unit (memory, etc.) and an auxiliary storage medium (SSD, hard disk, etc.) More specifically, the data as shown in the table below is logged in the data logging unit 5.

[0043] [Table 1]

[0044] With this configuration, an operator or a maintenance person can check the beam intensity Ib of the processing laser beam B1 retroactively when an abnormality occurs in the device or processing quality. Therefore, when a defect is found in a later process, the cause can be quickly identified and a remedy can be quickly implemented, which is preferable.

[0045] The above-mentioned laser processing device 1 may be configured to include a display unit D, on which information regarding the beam intensity of the processing laser beam B1 is displayed. Specifically, the display unit D can be configured as an information display device (a so-called information display) connected to a computer or the like that constitutes the beam intensity calculation unit 42, the data logging unit 5, and the like. Here, the information regarding the beam intensity of the processing laser beam B1 includes the beam intensity Ib of the processing laser beam B1 calculated by the beam intensity calculation unit 42, the beam intensity ratio PR, the judgment result by the processing beam intensity judgment unit 43, the logging information recorded in the data logging unit 5, etc. Such a configuration is preferable because it allows an operator or maintenance person to quickly check information related to the beam intensity of the processing laser beam B1 when an abnormality occurs in the device or processing quality.

[0046] [Beam Intensity Adjustment Unit 3] In the above description, the beam intensity adjuster 3 includes the acousto-optic element 32 as the beam splitter 31. As shown in FIG. With this configuration, even if the laser oscillator has an output characteristic in which the beam intensity increases or decreases from immediately after the laser beam is emitted until a predetermined time has elapsed, as an inherent (i.e., repeatable) transient characteristic, the processing laser beam B1 adjusted to a constant beam intensity Ib can be irradiated toward the workpiece W, which is preferable. In this state, if the beam intensity of the laser beam B0 emitted from the laser oscillator 2 suddenly fluctuates, it can be measured as a fluctuation in the beam intensity Ibz of the non-processing laser beam Bz, so that processing can be performed while measuring (monitoring) the beam intensity Ib without causing energy loss in the processing laser beam B1.

[0047] However, in applying the present invention, the beam splitting section 31 may be a beam splitting means other than the acousto-optical element 32, and may be configured to adjust the rotation angle, tilt angle, etc. of a variable beam splitter or polarizing plate, for example. Specifically, an actuator is provided to change the rotation angle and tilt angle, and by controlling the actuator from outside, the laser beam is split into an emitted processing laser beam B1 and a rejected non-processing laser beam Bz at an arbitrary beam intensity ratio PR. With this configuration, the processing laser beam B1, which is part of the laser beam B0 emitted from the laser oscillator 2 and is irradiated onto the workpiece W, can be adjusted to the desired beam intensity Ib, and processing can be performed while measuring (monitoring) the beam intensity Ib without causing any energy loss in the processing laser beam B1.

[0048] In the above description, a configuration in which the positions and angles of the mirrors M2 and M3 are fixed has been exemplified as the laser processing device 1. However, the laser processing device 1 is not limited to this configuration, and may be configured to include a mechanism for controlling the angle of the mirrors, called a galvano scanner, and to scan and irradiate a predetermined range (so-called processing area) with the processing laser beam B1.

[0049] In the above description, a configuration in which a laser beam B0 of the second harmonic (wavelength 532 nm) of a YAG laser (fundamental wavelength 1064 nm) is emitted in a pulsed form is shown as an example of the laser oscillator 2. However, the present invention can be applied to other wavelengths (other visible light, ultraviolet light, infrared light, etc.) and also to continuous waves (so-called CW). [Explanation of symbols]

[0050] 1 Laser processing equipment 2 Laser Oscillator 3 Beam Intensity Adjustment Unit 4. Beam Intensity Measurement Instrument 5 Data logging section 31 Beam branching section 32 Acousto-optical element 41 Beam Intensity Measurement Instrument 42 Beam Intensity Calculation Section 43 Beam Intensity Judgment Unit CN control section D Display section H Board holding part M Moving part W Workpiece B0 laser beam B1 Processing laser beam Bz Non-processing laser beam Ib Beam intensity of the processing laser beam Ibz Beam intensity of non-processing laser beam PR beam intensity ratio Vt Trigger Signal Vrf control signal (RF signal)

Claims

1. A laser processing device that processes a workpiece by irradiating a laser beam, a laser oscillator that emits a laser beam; a beam intensity adjusting unit that adjusts the laser beam to a beam intensity for irradiating the workpiece by removing a portion of the laser beam; a beam intensity measuring unit that measures the beam intensity of the laser beam, the beam intensity adjusting unit includes a beam branching unit that branches the processing laser beam and the non-processing laser beam at an arbitrary beam intensity ratio; The beam intensity measurement unit includes: measuring the beam intensity of the non-processing laser beam rejected by the beam intensity adjusting unit, and calculating the beam intensity of the processing laser beam to be irradiated to the workpiece based on the beam intensity and the beam intensity ratio; The beam intensity adjusting unit adjusts the beam intensity ratio based on the beam intensity of the non-processing laser beam measured by the beam intensity measuring unit and a previously grasped transient characteristic of the beam intensity of the laser beam emitted from the laser oscillator. A laser processing device comprising:

2. A processing beam intensity determination unit that compares the beam intensity of the processing laser beam measured by the beam intensity measurement unit with a predetermined threshold value.

2. The laser processing device according to claim 1 .

3. A data logging unit that logs the beam intensity of the processing laser beam measured by the beam intensity measuring unit together with time.

3. The laser processing device according to claim 1 or 2.

4. A display unit that displays information regarding the beam intensity of the processing laser beam is provided.

4. The laser processing device according to claim 1, wherein the laser processing device is a laser processing apparatus having a laser beam passing through the ...

Images