Laser processing equipment and chip transfer equipment

Abstract

To provide a laser beam machining device capable of machining at a stable beam intensity immediately after emitting a laser beam.SOLUTION: A laser beam machining device for machining a workpiece by irradiating it with a laser beam includes: a laser oscillator for emitting a laser beam; an attenuator which is disposed in the middle of an optical path of the laser beam to adjust transmissivity of the laser beam; and a control unit for adjusting transmissivity by controlling the attenuator. The control unit controls the attenuator selectively with respect to a range by which a beam intensity of the laser beam emitted from the laser oscillator exceeds a fixed level, in order to damp the beam intensity of the laser beam emitted from the attenuator.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a laser processing apparatus that irradiates a laser beam to process a workpiece. For example, it relates to an apparatus that irradiates a chip component with a laser beam to transfer the chip component from a donor substrate arranged with a predetermined gap to a target substrate that is the target of chip transfer.

Background Art

[0002] Conventionally, for removing a thin film formed on a substrate or the like, an apparatus (laser processing apparatus) that irradiates a laser beam condensed on a spot (so-called laser ablation) is known.

[0003] And, a technique is known in which elements (chips) arranged on a transfer source substrate (donor substrate) are peeled off by laser ablation technology using a laser beam and a galvanometer scanner, and the peeled elements are transferred to a transfer destination substrate (target substrate) arranged opposite (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When a laser oscillator continuously emits a laser beam, there are some cases where the beam intensity rapidly increases, then decreases until a predetermined time elapses, and then becomes stable. And, after stopping the irradiation of the laser beam and then restarting the irradiation, there are some cases where the same phenomenon occurs. Such a laser oscillator has a beam intensity of the laser beam that becomes excessive for a predetermined time immediately after the irradiation of the laser beam, so it has been difficult to apply it to processing with a narrow process margin. On the other hand, for laser processing with a narrow process margin, a method of starting the processing after the beam intensity has stabilized in order to obtain the desired processing result can be considered. However, there are problems such as the need to block the laser beam until the beam intensity stabilizes, or the inability to start the processing until the beam intensity stabilizes.

[0006] Therefore, an object of the present invention is to provide a laser processing apparatus capable of performing processing with a beam intensity suitable for processing immediately after emitting a laser beam from a laser oscillator.

Means for Solving the Problems

[0007] In order to solve the above problems, one aspect of the present invention is A laser processing apparatus that irradiates a laser beam to process a workpiece, A laser oscillator that emits a laser beam, An attenuator disposed in the optical path of the laser beam to adjust the transmittance of the laser beam, A control unit that controls the attenuator to adjust the transmittance, The control unit Selectively controls the attenuator to lower the beam intensity of the laser beam emitted from the attenuator for a range in which the beam intensity of the laser beam emitted from the laser oscillator exceeds a certain level.

Effects of the Invention

[0008] Since processing can be performed with a beam intensity suitable for processing immediately after emitting a laser beam from the laser oscillator, processing can be started promptly without waiting for the beam intensity to stabilize.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In the following description, the three axes of the orthogonal coordinate system are denoted 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. Also, the Z direction is expressed such that the direction against gravity is upward and the direction in which gravity acts is downward. Further, the direction of rotation about the Z direction as the central axis is called the θ direction. Also, the X direction may be expressed as horizontal, the Y direction as vertical, and the XY direction as vertical and horizontal.

[0011] FIG. 1 is a schematic diagram showing the overall configuration of an example of an embodiment embodying the present invention. FIG. 1 shows a schematic diagram of a chip transfer device 1 which is a type of laser processing apparatus according to the present invention.

[0012] The laser processing apparatus according to the present invention irradiates a laser beam L to process a workpiece W. Here, as the workpiece W, a plurality of chip components C held at a predetermined pitch on the surface (lower surface side) of a donor substrate Wd disposed with a predetermined gap from a target substrate Wt to be transferred are exemplified.

[0013] The chip transfer device 1 transfers the plurality of chip components C one by one onto the surface (upper surface side) of the target substrate Wt by sequentially irradiating the laser beam L directly to the plurality of chip components C held at the predetermined pitch or by passing the laser beam L through the donor substrate Wd. Specifically, the chip transfer device 1 includes a laser oscillator 2, an attenuator 3, a substrate holding unit 4, a moving unit 5, a correction data registration unit 6, a processing pattern registration unit 8, a control unit 9, and the like. In the present invention, the laser beam L1 emitted from the laser oscillator 2 and the laser beam L2 emitted from the attenuator 3 may be referred to separately, or may be collectively referred to as the laser beam L.

[0014] The laser oscillator 2 emits a laser beam L1. Specifically, the laser oscillator 2 is configured to emit a pulsed laser beam L1 in response to a trigger signal output from the control unit 9. More specifically, as the laser oscillator 2, a green laser (wavelength 532 nm) that emits the second harmonic of a YAG laser (fundamental wavelength 1064 nm) as the laser beam L1 can be exemplified.

[0015] The attenuator 3 is disposed in the optical path of the laser beam L and adjusts the transmittance Q of the laser beam L. The transmittance Q can be expressed as "intensity of laser beam L2 / intensity of laser beam L1". Specifically, the attenuator 3 attenuates and emits the beam intensity I of the laser beam L1 emitted from the laser oscillator 2. Then, the laser beam L2 emitted from the attenuator 3 is irradiated onto the chip component C via a mirror M or the like, and transfer processing is performed. More specifically, the attenuator 3 can be exemplified by an acousto-optic element 31.

[0016] The acousto-optic element 31 is disposed in the optical path of the laser beam L1 and selectively reduces the beam intensity of the laser beam L1 passing through the acousto-optic element 31. Specifically, the acousto-optic element 31 branches the laser beam L1 into the zeroth-order light that travels straight and is emitted, and the nth-order light (i.e., the first-order light, the second-order light, etc.) that diffracts and is emitted in a direction different from that of the zeroth-order light, while adjusting the intensity ratio of the zeroth-order light and the nth-order light (and thus the transmittance Q of the laser beam L). That is, a part of the incident laser beam L1 is branched as the nth-order light, and the zeroth-order light with its remaining beam intensity adjusted is emitted as the laser beam L2 with its beam intensity selectively reduced and irradiates the chip component C. Note that the transmittance Q of the laser beam L is adjusted by the acousto-optic element 31 according to the voltage Vrf of the RF signal output from the control unit 9. Also, the nth-order light unnecessary for laser processing has its energy absorbed by an extinction device (not shown) or the like.

[0017] The mirror M changes the direction of the laser beam L2. In the configuration shown in FIG. 1, the laser beam L2 emitted in the X direction is directed downward and irradiates the chip component C.

[0018] The substrate holding unit 4 holds the donor substrate Wd and the target substrate Wt while arranging them with a predetermined gap therebetween. Specifically, the substrate holding unit 4 supports the target substrate Wt while keeping it in a horizontal state from the lower surface side, and supports the side surface or the lower outer periphery of the donor substrate Wd above it, and holds these substrates Wt and Wd. More specifically, the substrate holding unit 4 includes a donor substrate holding unit 4d provided with negative pressure suction means, electrostatic adhesion means, etc., and a target substrate holding unit 4t provided with a clamping mechanism, negative pressure suction means, etc.

[0019] The moving unit 5 changes the irradiation position of the laser beam L2 with respect to the workpiece W. Specifically, it moves the relative positions of the donor substrate Wd, the target substrate Wt, and the laser beam L2 in the direction (XY direction) orthogonal to the irradiation direction (Z direction) of the laser beam L2. More specifically, the moving unit 5 includes an X-axis actuator 5x, a Y-axis actuator 5y, a θ-axis actuator 5θ, etc.

[0020] The X-axis actuator 5x moves the substrate holder 4 in the X direction (specifically, the X1 direction) at a predetermined speed and stops it at a predetermined position. The Y-axis actuator 5y moves the substrate holder 4 in the Y direction (specifically, the Y1 direction) at a predetermined speed and stops it at a predetermined position. The θ-axis actuator 5θ rotates the substrate holder 4 at a predetermined angular velocity in the θ direction with the Z direction as the rotation axis and stops it at a predetermined angle. Specifically, the X-axis actuator 5x is attached above the apparatus frame 10f, the Y-axis actuator 5y is attached to the movable part 50 of the X-axis actuator 5x, the θ-axis actuator 5θ is attached to the movable part (not shown) of the Y-axis actuator 5y, and the substrate holder 4 is attached to the movable part (not shown) of the θ-axis actuator 5θ. Then, the X-axis actuator 5x, the Y-axis actuator 5y, and the θ-axis actuator 5θ drive and control each movable part based on the control signal output from the control unit 9.

[0021] Note that the alignment of the target substrate Wt and the donor substrate Wd can be achieved by a mechanical clamping method that clamps the outer peripheral portions of these substrates Wd and Wt from the outside to the inside, imaging the reference marks provided on these substrates Wd and Wt with a camera, imaging the notches or orientation flats provided on these substrates Wd and Wt with a camera / detecting them with a sensor, etc., grasping the positional deviation and angular deviation, and positioning and moving and correcting the angle of the donor substrate Wd by stage mechanisms 52x, 52y, etc. that can be finely moved and stopped independently in the X direction (specifically, the X2 direction) / Y direction (specifically, the Y2 direction) / θ direction.

[0022] The correction data registration unit 6 registers correction data K for correcting the temporal intensity change of the laser beam L for a range in which the beam intensity I of the laser beam L exceeds a certain level. Note that the "range" in which the beam intensity I of the laser beam L exceeds a certain level means a temporal "interval" (also referred to as a period). The correction data K is for changing the transmittance Q of the attenuator 3 over time so that the beam intensity I of the laser beam L irradiated on the chip component C does not exceed a certain level. Specifically, the correction data K is associated with the change in the characteristic value with respect to the elapsed time t from immediately after the irradiation of the laser beam L (that is, immediately after the input of the trigger signal Vt). More specifically, the correction data K can be defined as the time-series data of the voltage Vrf of the RF signal applied to the acousto-optic element 31 which is the attenuator 3, and examples thereof include a function (for example, expressed by an equation: Vrf = f(t), etc.) in which the voltage value of the RF signal to be applied changes with time t, and a look-up table in which the time t and the voltage Vrf of the RF signal to be applied are associated.

[0023] Note that the correlation between the voltage Vrf of the RF signal applied to the acousto-optic element 31 which is the attenuator 3 and the transmittance Q is grasped in advance, and the voltage Vrf of the RF signal to be applied is set so that the beam intensity I of the laser beam L1 falls within a desired range. Specifically, regarding the laser beam L1 emitted from the laser oscillator 2, the change characteristic (so-called power characteristic) of the beam intensity I over time before adjusting the transmittance is grasped in advance. More specifically, a pulsed trigger signal is continuously output to the laser oscillator 2 at a predetermined repetition frequency, and using a measuring instrument with good high-speed responsiveness, the beam intensity I is sequentially measured and recorded from immediately after the emission of the laser beam L1 until a predetermined time has elapsed.

[0024] [Regarding Beam Intensity Adjustment / Correction Data] The details of the adjustment of the beam intensity I of the laser beam L during chip transfer will be described below.

[0025] FIG. 2 is a graph showing the change characteristic of the beam intensity of the laser beam over time in an example of the embodiment embodying the present invention. In FIG. 2, with the horizontal axis being the time t and the vertical axis being the beam intensity I, the state of the change in the beam intensity I (that is, the power characteristic Pb before adjustment) when the laser beam L1 is emitted under processing conditions similar to actual chip transfer is illustrated.

[0026] Under these processing conditions, a cycle is repeated in which the laser beam L1 is emitted for a predetermined time (i.e., the irradiation time Ts), then the emission is stopped for a predetermined time (i.e., the pause time Tq), and then the laser beam L1 is emitted again for a predetermined irradiation time Ts.

[0027] Before time t0, the laser oscillator 2 is made to standby in an excited state (i.e., a state in which the laser beam L1 can be immediately emitted when a trigger signal is input). Then, from time t0 to time t3 when the irradiation time Ts has elapsed, a trigger signal is input at a predetermined repetition frequency. Also, after interrupting the input of the trigger signal (i.e., turning off the trigger signal) at time t3, the trigger signal is input again at time t10 when the pause time Tq has elapsed, and the trigger signal is turned off at time t13 when the irradiation time Ts has elapsed. At this time, the beam intensity I of the laser beam L1 rapidly increases from time t0 to time t1, decreases from time t1 to time t2, and stabilizes after time t2. Then, after the pause time Tq has elapsed from time t3 to time t10, when the irradiation of the laser beam L1 is resumed, the beam intensity I rapidly increases from time t10 to time t11, decreases from time t11 to time t12, and stabilizes after time t12. The following similar phenomena continue. Note that such a change in the beam intensity I over time (i.e., the power characteristic Pb) depends on processing conditions such as the individual laser oscillator 2 and the repetition frequency of the trigger signal Vt, and is reproducible.

[0028] FIG. 3 is a conceptual diagram showing the time-dependent characteristics of each parameter related to the adjustment of the beam intensity in an example of an embodiment embodying the present invention. FIGS. 3(a) to (c) show the time t expanded from FIG. 2 on the horizontal axis in order to focus on the period from time t0 to time t2.

[0029] Figure 3(a) is a graph comparing the power characteristic Pb of the laser beam L before applying the present invention and the power characteristic Pc of the laser beam L2 after applying the present invention. In Figure 3(a), the beam intensity I is shown on the vertical axis, and the change in the beam intensity I of the laser beam L1 over time (i.e., the power characteristic Pb before adjustment) and the change in the beam intensity I of the laser beam L2 over time (i.e., the power characteristic Pc after adjustment) are shown side by side. Note that the upper limit value R1 and the lower limit value R2 of the beam intensity suitable for chip transfer are grasped in advance based on the transfer state of the chip component C and the like. Then, the timing when the beam intensity I of the laser beam L1 exceeds a certain level (i.e., the upper limit value R1) (i.e., the time Ta from time t0 to time ta) and the timing when it falls below the upper limit value R1 again (i.e., the time Tc from time t0 to time tb) are grasped based on the power characteristic Pb before adjustment. Figure 3(b) is a diagram showing the state of the trigger signal Vt input to the laser oscillator 2. In Figure 3(b), the voltage of the trigger signal Vt is shown on the vertical axis. Note that the trigger signal Vt is input at a predetermined repetition frequency after time t0, and the laser beam L1 is sequentially emitted in response to the input of the trigger signal Vt. In Figure 3(c), the voltage Vrf of the RF signal applied to the acousto-optic element 31 which is the attenuator 3 and the transmittance Q of the acousto-optic element 31 are shown on the vertical axis, and the state of the change over time of the voltage Vrf and the transmittance Q is illustrated.

[0030] Until the time Ta when the beam intensity I of the laser beam L1 exceeds a certain level (i.e., the upper limit value R1), the voltage Vrf of the RF signal is not applied to the acousto-optic element 31. Then, just before the time Ta elapses, the voltage Vrf of the RF signal is started to be applied, and the voltage Vrf of the RF signal is increased until the time Tb elapses. Then, after the time Tb has elapsed, the voltage Vrf of the RF signal is applied while gradually decreasing it, and after the time Tc has elapsed, the application is stopped. That is, the transmittance Q of the attenuator 3 is in the highest state from the time t0 immediately after the input of the trigger signal Vt until the time Ta has elapsed. Then, the transmittance Q is sequentially decreased from the time when Ta has elapsed until the time Tb has elapsed. Then, the transmittance Q is gradually increased from the time when Tb has elapsed until the time Tc has elapsed. After the time Tc has elapsed, the transmittance Q becomes the highest state again. That is, by sequentially changing the voltage Vrf of the RF signal applied to the acousto-optic element 31, the transmittance Q of the attenuator 3 can be sequentially changed, and the beam intensity I of the emitted laser beam L2 can be selectively decreased. Therefore, the laser beam L2 can be irradiated onto the chip component C with the power characteristic Pc as shown in Fig. 3(a).

[0031] The processing pattern registration unit 8 registers the processing pattern information J necessary for processing the workpiece W. Specifically, the processing pattern information J is also called a processing recipe, and the arrangement location (coordinates and pitch) of the chip transfer C held on the donor substrate Wd, the order and moving speed of irradiating the laser beam L (so-called processing route and processing speed), the repetition frequency of the trigger signal Vt output to the laser oscillator 2, etc. are registered. In addition, correction data K is registered in association with the processing pattern information J. Therefore, the correction data K suitable for the output pattern of the trigger signal Vt can be set.

[0032] The control unit 9 controls each part of the chip transfer device 1. Furthermore, the control unit 9 selectively controls the attenuator 3 to decrease the beam intensity of the laser beam L2 emitted from the attenuator 3 with respect to the range (that is, the time interval) in which the beam intensity I of the laser beam L1 emitted from the laser oscillator 2 exceeds a certain level. Specifically, the control unit 9 has the following functions. · Transmit a trigger signal for irradiating the laser beam L to the laser oscillator 2 in a pulsed manner. · Adjust the voltage Vrf of the RF signal output to the acousto-optic element 31 (that is, control the attenuator 3) to adjust the transmittance Q of the laser beam L from immediately after the laser beam L is emitted until a predetermined time has elapsed. · Correct (that is, align) the positional deviation and angular deviation of the donor substrate Wd with respect to the target substrate Wt. · While grasping the current position information of the X-axis actuator 5x, Y-axis actuator 5y, θ-axis actuator 5θ, etc., control the position, moving speed of the X-axis actuator 5x and Y-axis actuator 5y, the angle of the θ-axis actuator 5θ, etc. (that is, relatively move the substrates Wd, Wt and the laser beam L2). · Based on the processing pattern information J registered in the processing pattern registration unit 8, sequentially irradiate the chip components C distributed on the donor substrate Wd with the laser beam B2, and transfer the chip components C from the donor substrate Wd to the target substrate Wt (that is, a form of laser processing). At this time, based on the correction data K, sequentially control the voltage Vrf of the RF signal according to the output timing of the trigger signal Vt (that is, the elapsed time t from immediately after laser irradiation) (that is, sequentially adjust the transmittance Q of the attenuator 3).

[0033] More specifically, the control unit 9 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.

[0034] [Processing Flow] FIG. 4 is a flowchart in an example of an embodiment embodying the present invention. FIG. 4 shows a flow of irradiating the chip component C with the laser beam L using the chip transfer device 1 according to the present invention and transferring the chip component C from the donor substrate Wd side to the target substrate Wt side (that is, a type of laser processing).

[0035] First, determine the conditions for performing the transfer process (step s10). Specifically, the arrangement location (coordinates and pitch) of the chip transfer C held on the donor substrate Wd, the order of irradiating the laser beam L2 and the moving speed (so-called processing route and processing speed), the repetition frequency of the trigger signal output to the laser oscillator 2, etc. are determined and registered in the processing pattern registration unit 8 as the processing pattern information J.

[0036] It is determined whether this processing pattern information J is a new processing condition or an existing processing condition (step s11).

[0037] If the processing pattern information J is a new processing condition, the power characteristics of the laser beam L1 emitted from the laser oscillator 2 are measured (step s12). Specifically, from immediately after the emission of the laser beam L1 until the time when the beam intensity I becomes sufficiently stable, the change in the beam intensity I over time is measured for each pulse or a plurality of pulses using a power measuring device with excellent high-speed responsiveness. Then, based on the obtained change in the beam intensity I over time (that is, the power characteristics), correction data K is created and registered (step s13). On the other hand, if the processing pattern information J is an existing processing condition, the correction data K is read out (step s14).

[0038] Next, the target substrate Wt is held by the substrate holding unit 4 (step s20). After that, the donor substrate Wd is held by the substrate holding unit 4 (step s21). Then, while these substrates Wt and Wd are arranged to face each other with a predetermined gap therebetween, alignment in the XYθ directions is performed (step s22).

[0039] Next, while maintaining the positional relationship between these substrates Wt and Wd, the moving unit 5 is controlled to relatively move with the laser beam L2, and the beam intensity I is selectively decreased while sequentially irradiating the chip component C with the laser beam L2 (step s23). By doing so, the chip component C is sequentially transferred from the donor substrate Wd side to the target substrate Wt side.

[0040] After one column of chip transfer is completed, it is determined whether to transfer the next column (step s24). When transferring the next column, steps s23 to s24 described above are repeated. If there is no next column, the donor substrate Wd is dispensed (step s25).

[0041] Then, it is determined whether the chip transfer has been completed (step s26). If not, steps s21 to s26 described above are repeated. On the other hand, if the chip transfer has been completed, the target substrate Wt is dispensed (step s27), and a series of processes is terminated.

[0042] Due to such a configuration, the chip transfer device 1 can irradiate the chip components C arranged in a large number on the donor substrate Wd one by one with the laser beam L2 sequentially while relatively moving the moving part 5. Then, gas is generated at the interface between the chip component C irradiated with the laser beam L2 and the donor substrate Wd, and the chip component C separates from the donor substrate Wd and jumps out vigorously toward the target substrate Wt and adheres to the target substrate Wt (that is, is transferred). At this time, the intensity I of the laser beam L1 emitted from the laser oscillator 2 is sequentially attenuated during a predetermined period (that is, between time ta and time tb). And even when the laser beam L1 is continuously emitted and the beam intensity I rapidly rises, drops until a predetermined time elapses, and then becomes stable, by selectively reducing the too-high beam intensity I, the laser beam L2 emitted from the attenuator 3 can be reduced to a beam intensity suitable for processing and irradiate the workpiece such as the chip component C. Therefore, since processing can be performed with the beam intensity I suitable for processing immediately after the laser beam L is emitted from the laser oscillator 2, processing can be started promptly without waiting for the beam intensity I to stabilize. In particular, the present invention is suitable when it is desired to quickly perform laser processing with a narrow process margin such as chip transfer.

[0043] [Modification Example] [Regarding Correction Data] In the above description, the chip transfer device 1 is provided with the correction data registration unit 8, and the control unit 9 reduces the beam intensity of the laser beam L2 emitted from the attenuator 3 based on the correction data K. However, in implementing the present invention, the chip transfer device 1 is not limited to the configuration in which the correction data K is provided in the correction data registration unit 6. For example, it is also possible to use another device or the like to generate processing conditions (so-called offline processing), control the voltage Vrf of the RF signal applied to the acousto-optic element 31 according to the processing conditions, and adjust the transmittance Q of the attenuator 3. Even in this case, since the beam intensity I of the laser beam L2 emitted from the attenuator 3 is selectively reduced, even in laser processing with a narrow process margin, processing can be performed with a stable beam intensity immediately after the laser beam is emitted.

[0044] [Adjustment of the transmittance Q until a predetermined time elapses after irradiation] In the above description, an example of the configuration in which the correction data K corresponds to the time during which the laser beam L is continuously output in a pulsed manner from immediately after the laser beam L is emitted until a predetermined time Tc elapses has been illustrated. With such a configuration, even if the laser oscillator 2 is kept in an excited state and waiting, from immediately after the input of the trigger signal Vt until a predetermined time Tc elapses (that is, for the period exceeding the upper limit value R1 of the beam intensity suitable for chip transfer), the beam intensity I can be selectively reduced, which is preferable. Also, when the pause time Tq is long, or when the pause time Tq is short but the power characteristics when restarting the irradiation of the laser beam L1 are the same, such a configuration can be adopted.

[0045] [Correction of the pause time] On the other hand, when the pause time Tq is short, or when the pause time Tq is slightly long and the power characteristics when restarting the irradiation of the laser beam L1 cannot be regarded as the same and exceed the upper limit value R1 of the beam intensity suitable for chip transfer, the correction data K may also be configured to correspond to the time Ts during which the laser beam L is continuously output in a pulsed manner and the time Tq during which the output is paused from immediately after the laser beam L is emitted until a predetermined time elapses.

[0046] FIG. 5 is a conceptual diagram showing the time-dependent characteristics of each parameter related to the adjustment of the beam intensity in an example of the embodiment embodying the present invention. In FIGS. 5(a) to 5(c), the time t is shown on the horizontal axis. After continuously emitting the laser beam L for a predetermined time Ts, the emission is stopped for a predetermined pause time Tq, and then when the laser beam L is emitted again for the predetermined time Ts, the time-dependent characteristics of each parameter are shown.

[0047] FIG. 5(a) shows a graph comparing the power characteristic Pb of the laser beam L before applying the present invention and the power characteristic Pc of the laser beam L2 after applying the present invention. FIG. 5(b) shows the state of the trigger signal Vt input to the laser oscillator 2. FIG. 5(c) shows the voltage Vrf of the RF signal applied to the acousto-optic element 31 which is the attenuator 3 and the transmittance Q of the acousto-optic element 31 on the vertical axis, and shows the state of the time-dependent changes of the voltage Vrf and the transmittance Q.

[0048] For example, from time t0, the trigger signal Vt is continuously input, and the laser beam L1 is sequentially emitted. At this time, the beam intensity I of the laser beam L is between the upper limit value R1 and the lower limit value R2 (that is, within the range suitable for the transfer of the chip component C). Then, after passing time t21, it exceeds the upper limit value R1, becomes maximum at time t22, and gradually weakens until time t23 when the continuous irradiation time Ts ends. Then, at time t23, the trigger signal Vt stops, and the irradiation of the laser beam L1 stops. Then, from time t24 when a predetermined time (that is, the pause time Tq) has elapsed from time t23, the input of the trigger signal Vt starts again, and the irradiation of the laser beam L1 resumes. In the case of this example, the intensity I of the laser beam L1 rises again from time t24, becomes maximum at time 25, and gradually weakens until time t26 when the continuous irradiation time Ts ends. Then, at time t26, the trigger signal Vt stops, and the irradiation of the laser beam L1 stops. After grasping that the beam intensity I of the laser beam L1 has such a power characteristic Pb, the correction data K is defined in the same manner as described above and registered in the correction data registration unit 6. Specifically, after measuring the output pattern of the laser beam L (the change in beam intensity I over time (i.e., the power characteristic Pb before adjustment)), the correction data K is defined such that the voltage Vrf of the RF signal applied to the attenuator 3 (i.e., the transmittance Q of the attenuator 3) is adjusted to selectively decrease the beam intensity I during the period when the beam intensity I exceeds a certain level (i.e., the upper limit value R1) in correspondence with the irradiation time Ts and the pause time Tq from time t0 to time t26. More specifically, after time Ta has elapsed since the laser beam L1 was irradiated and after time t21, since the beam intensity I exceeds the upper limit value R1, the voltage Vrf of the RF signal applied to the attenuator 3 (i.e., the transmittance Q of the attenuator 3) is set in accordance with the increase and decrease of the beam intensity I. By doing so, the laser beam L2 can be irradiated onto the chip component C with the power characteristic Pc as shown in Fig. 5(a).

[0049] Note that, for the sake of simplicity in the above description, an example is shown where the continuous irradiation time Ts occurs twice and there is one pause time Tq in between. However, in actual transfer processing, when the continuous irradiation time Ts is repeated multiple times and a pause time Tq is set in between, the power characteristic Pb should be grasped according to the processing pattern and the correction data K should be defined. Also, when the correction data K is defined as a function in which the voltage value of the RF signal to be applied changes with time t, it may be an expression such that the voltage value Vrf is determined according to the elapsed time of the irradiation time Ts and the pause time Tq.

[0050] [Regarding the correction data K] Note that in the above, as an example of the correction data K, a configuration is exemplified in which the beam intensity I of the laser beam L2 emitted from the attenuator 3 is maintained at a value slightly lower than the upper limit value R1 of the beam intensity suitable for chip transfer. With such a configuration, since the energy loss of the laser is small, the repetition frequency of the trigger signal can be set high to increase the processing speed. However, the correction data K is not limited to such a configuration, and may be a configuration that maintains the median value between the upper limit value R1 and the lower limit value R2 of the beam intensity suitable for chip transfer, or may be a configuration that maintains a value slightly higher than the lower limit value R2.

[0051] [Regarding the attenuator 2] In the above description, an acousto-optic element was exemplified as the specific configuration of the attenuator 2. In implementing the present invention, if an acousto-optic element with a high response speed is used as a means for selectively reducing the beam intensity I of the laser beam L, it is preferable because the beam intensity I can be easily adjusted even when the beam intensity I changes in a short time. However, if it can follow the change in the beam intensity I, an optical element such as an optical wedge or a filter may be arranged, and an attenuator or the like that can change the transmittance of the laser beam passing through by adjusting the angle and position of this optical element may be used as the attenuator 2.

[0052] [Regarding the transfer process] In the above description, as the chip transfer device 1, a configuration was exemplified in which the laser beam L is sequentially irradiated directly to a plurality of chip components C held at a predetermined pitch or through a donor substrate Wd, and the plurality of chip components C are transferred one by one to the target substrate Wt. However, in implementing the present invention, it is not limited to a configuration in which the transfer is performed one chip at a time, and a plurality of chips may be transferred together by sequentially irradiating a laser beam L branched toward a plurality of chips or a laser beam L in a range including a plurality of chips in response to a trigger signal Vt.

[0053] [Regarding the laser processing device] In the above description, the chip transfer device 1 was shown as a specific application example of the present invention. However, the present invention is not limited to the chip transfer device, and can be applied to a laser processing device that processes a workpiece with a narrow process margin in exposure, marking, trimming, etc. In this case, it is preferable because processing can be performed with a stable beam intensity immediately after the laser beam is emitted.

Explanation of reference numerals

[0054] 1 Chip transfer device 2 Laser oscillator 3 Attenuator 4 Substrate holding part 5 Moving part 6 Correction data registration part 8 Processing pattern registration part 9 Control part 31 Acousto-optic element W Workpiece Wd Donor substrate Wt Target substrate C Chip component L Laser beam L1 Laser beam emitted from the laser oscillator L2 Laser beam that has passed through the attenuator I Beam intensity J Processing pattern information K Correction data t0~t3,t10~t13 Time Ts Irradiation time Tq Pause time Vt Trigger signal Vrf Voltage of the RF signal Q Transmittance R1 Upper limit value R2 Lower limit value Pb Power characteristic before adjustment Pc Power characteristic after adjustment

Claims

1. A laser processing device that processes a workpiece by irradiating a laser beam, a laser oscillator that emits the laser beam; an attenuator disposed in an optical path of the laser beam to adjust the transmittance of the laser beam; a control unit that controls the attenuator to adjust the transmittance, The control unit A laser processing apparatus characterized in that, for a range in which the beam intensity of the laser beam emitted from the laser oscillator exceeds a certain level, the attenuator is controlled to selectively reduce the beam intensity of the laser beam emitted from the attenuator.

2. a correction data registration unit that registers correction data for correcting a change in intensity of the laser beam over time for a range in which the beam intensity of the laser beam exceeds a certain level; The control unit reduces the beam intensity of the laser beam emitted from the attenuator based on the correction data.

2. The laser processing device according to claim 1 .

3. The correction data corresponds to a time during which the laser beam is continuously output in a pulsed form from immediately after the laser beam is emitted until a predetermined time has elapsed.

3. The laser processing device according to claim 2 .

4. The correction data corresponds to a time during which the laser beam is continuously output in a pulsed form and a time during which the output is stopped, from immediately after the laser beam is emitted until a predetermined time has elapsed.

3. The laser processing device according to claim 2 .

5. The attenuator is an acousto-optical element.

5. 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 ...

6. the workpiece is a plurality of chip components held at a predetermined pitch on a surface of a donor substrate oriented and arranged with a predetermined gap between them and a target substrate to be transferred; The laser processing device sequentially irradiates the laser beam directly or through the donor substrate onto the plurality of chip components held at the predetermined pitch, thereby transferring the plurality of chip components one by one onto the target substrate.

6. A chip transfer device according to claim 1, wherein the chip transfer device is a microcomputer.

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