Laser processing device, laser machining device, transfer device, laser processing method, laser machining method, and transfer method

Abstract

The present invention provides a laser processing device that comprises: a laser device for oscillating laser light; a reduced projection optical system; and a substrate stage, and performs laser processing by irradiating a substrate disposed on the substrate stage with a laser. The laser processing device has a shutter between the reduced projection optical system and the substrate stage. Accordingly, it is possible to provide a laser processing device capable of suppressing the effects of dimensional changes in the reduced projection optical system due to temperature changes in the reduced projection optical system, and suppressing a decrease in the throughput of the laser processing.

Description

Laser processing device, laser processing device, transfer device, laser processing method, laser processing method, and transfer method

[0001] The present invention relates to a laser processing device, a laser processing device, a transfer device, a laser processing method, a laser processing method, and a transfer method.

[0002] Semiconductor package substrates have been actively developed in line with the trend of "More Than Moore" to SoC (System on a Chip), which integrates a system into a single chip.

[0003] Furthermore, the configuration of semiconductor package substrates is becoming more complex and denser, and devices using excimer lasers are being used to manufacture the base substrates.

[0004] For example, Patent Document 1 describes a laser processing device that emits a beam of laser light from a laser oscillator, aligns the direction of the principal ray of the laser light by passing it through an fθ lens (a focusing lens), and irradiates the workpiece with the laser light (pulse laser light), thereby performing laser processing on the workpiece.

[0005] International Publication No. 2013 / 094025

[0006] In the case of a laser processing device or method that performs laser processing such as laser processing by irradiating a workpiece with a laser through a lens, if the laser oscillation of the laser oscillator is turned off when laser processing is not being performed, it takes time for the laser output to stabilize the next time laser oscillation is started.

[0007] By providing a removable shutter in the laser beam path on the laser incident side of the lens and continuously oscillating the laser, it is expected that the laser output can be stabilized. However, when the shutter is removed and the laser beam path to the lens, which is a reduction projection optical system, is opened, the lens is also exposed to laser irradiation, causing it to heat up. However, until the lens is sufficiently warmed up and the temperature change of the lens disappears, the lens's dimensions continue to change, causing the laser output from the lens to become unstable. This creates the problem of waiting until the lens's dimensions stop changing and the laser output stabilizes. Furthermore, it is sometimes necessary to adjust the device each time the shutter is opened or closed. As a result, there is the problem of reduced laser processing throughput.

[0008] The present invention has been made to solve the above problems, and aims to provide a laser processing apparatus and a laser processing method that can suppress a decrease in throughput due to a change in temperature of the reduction projection optical system when switching between laser non-irradiation and laser irradiation on the substrate to be processed. Another aim is to perform stable processing that is not affected by deformation due to the temperature of the reduction optical system even when the interval between laser processing changes.

[0009] The present invention has been made to achieve the above-mentioned object, and provides a laser processing apparatus that includes a laser device that oscillates laser light, a reduction projection optical system, and a substrate stage, and that performs laser processing by irradiating a laser onto a substrate placed on the substrate stage, and that has a shutter between the reduction projection optical system and the substrate stage.

[0010] According to this laser processing apparatus, since the laser can be irradiated onto the reduction projection optical system even when the laser optical path is blocked by the shutter, the temperature of the reduction projection optical system can be maintained at the same temperature as when the object is being laser processed, the influence of dimensional changes of the reduction projection optical system due to temperature changes can be suppressed, and a decrease in the throughput of the laser processing can be suppressed. Furthermore, since the shape and position of the laser irradiation can be stabilized, stable laser processing can always be performed regardless of the interval between laser processing.

[0011] In this case, the shutter can be a laser processing device in which an optical path changing member that forms an inclined surface with respect to the optical axis of the laser can be placed on the optical axis of the laser and can be removed from the optical axis of the laser.

[0012] This allows the laser light path to be easily opened and closed.

[0013] In this case, the laser processing device may be provided with a damper that absorbs the energy of the laser on the switched optical path of the laser when the shutter blocks the optical axis of the laser and the optical path of the laser is switched.

[0014] This makes it possible to improve safety and effectively prevent damage to the device caused by the laser whose optical path has been switched.

[0015] In this case, the laser processing device may be a laser processing device that includes the laser processing device and that irradiates the substrate with a laser to process the shape of the surface of the substrate.

[0016] This makes it possible to suppress a decrease in throughput of laser processing, and to perform shape processing on the surface of the substrate with stable positioning and precision.

[0017] In this case, the transfer device can be equipped with the above-mentioned laser processing device, and can transfer an object to be transferred provided on the substrate to another substrate by irradiating the object with a laser through the substrate.

[0018] This makes it possible to suppress a decrease in throughput of transferring the object to be transferred by laser irradiation, and to transfer the object to another substrate reliably and at a stable transfer position.

[0019] The present invention also provides a laser processing method for performing laser processing by irradiating a laser onto a substrate placed on the substrate stage using a laser processing device including a laser device that oscillates laser light, a reduction projection optical system, a substrate stage, and a shutter between the reduction projection optical system and the substrate stage, wherein the shutter is closed while the laser light is oscillated when the laser is not irradiated onto the substrate.

[0020] According to this laser processing method, the laser is irradiated onto the reduction projection optical system even when the laser light path is blocked by the shutter, so that the temperature of the reduction projection optical system can be maintained at the same temperature as when the object to be processed is laser processed, thereby suppressing the effects of dimensional changes in the reduction projection optical system due to temperature changes and suppressing a decrease in the throughput of the laser processing.

[0021] In this case, the laser processing method can be such that the shutter is an optical path changing member that forms an inclined surface with respect to the optical axis of the laser and that can be placed on the optical axis of the laser and removed from the optical axis of the laser.

[0022] This makes it possible to easily block or open the laser optical path.

[0023] At this time, the laser processing method can be such that the optical path of the laser is switched by closing the shutter, and the energy of the laser is absorbed by a damper arranged on the switched optical path of the laser.

[0024] This can improve safety and effectively prevent damage to the device caused by the laser whose optical path has been switched.

[0025] In this case, the above-described laser processing method can be used as a laser processing method in which the laser processing is carried out to shape the surface of the substrate.

[0026] This makes it possible to suppress a decrease in throughput of laser processing, and to perform shape processing on the surface of the substrate with stable positioning and precision.

[0027] In this case, the laser processing method can be used as a transfer method in which a transfer object provided on the substrate is transferred to another substrate by irradiating the laser through the substrate onto the transfer object.

[0028] This makes it possible to suppress a decrease in throughput of transferring the object to be transferred by laser irradiation, and to transfer the object to another substrate reliably and at a stable transfer position.

[0029] As described above, according to the laser processing device of the present invention, since light is irradiated onto a reduction projection optical system, the temperature of the reduction projection optical system can be maintained at the same temperature as that during laser processing of the object to be processed, thereby suppressing the effects of dimensional changes in the reduction projection optical system due to temperature changes and suppressing a decrease in throughput of laser processing.

[0030] According to the laser processing device of the present invention, it is possible to suppress a decrease in throughput of shaping the surface of a substrate by laser, and it is possible to perform shaping on the surface of a substrate at a stable position and with stable accuracy.

[0031] According to the transfer device of the present invention, it is possible to suppress a decrease in throughput of transferring an object to be transferred by laser irradiation, and it is possible to transfer an object to another substrate reliably and at a stable transfer position.

[0032] According to the laser processing method of the present invention, the laser is irradiated onto the reduction projection optical system even when the laser light path is blocked by the shutter, so that the temperature of the reduction projection optical system can be maintained at the same temperature as during laser processing of the object to be processed, thereby suppressing the effects of dimensional changes in the reduction projection optical system due to temperature changes and making it possible to suppress a decrease in laser processing throughput.

[0033] According to the laser processing method of the present invention, it is possible to suppress a decrease in throughput of shaping the surface of a substrate with a laser, and to perform shaping on the surface of a substrate with stable positioning and accuracy.

[0034] According to the transfer method of the present invention, it is possible to suppress a decrease in throughput of transferring an object to be transferred by laser irradiation, and the object to be transferred can be transferred to another substrate reliably and at a stable transfer position.

[0035] FIG. 1 is a schematic diagram showing an example of a laser processing device of the present invention. FIG. 2 is a schematic diagram showing an example of laser irradiation in the laser processing method of the present invention. FIG. 3 is a schematic diagram showing out-focus of the laser irradiation in FIG. 2. FIG. 4 is a schematic diagram showing an example of the laser processing method of the present invention. FIG. 5 is a schematic diagram showing another example of laser irradiation in the laser processing method of the present invention. FIG. 6 is a schematic cross-sectional view showing an example of a recess that can be formed by the laser processing method of the present invention. FIG. 7 is an intensity distribution of an example of a laser that can be used in the laser processing method of the present invention. FIG. 8 is a schematic diagram showing a first embodiment of a transfer device (laser lift-off device) of the present invention. FIG. 9 is a schematic diagram showing a second embodiment of the transfer device (laser lift-off device) of the present invention. FIG. 10 is a schematic diagram showing a collective transfer step in an example of the transfer method of the present invention.

[0036] As described above, there has been a need to provide a laser processing apparatus and a laser processing method that can suppress a decrease in throughput due to a change in temperature of the reduction projection optical system when switching between non-irradiation and irradiation of the laser on the substrate, which is the workpiece, and a change in the processing position and processing accuracy.

[0037] As a result of extensive research into the above-mentioned problems, the inventors discovered that by providing a shutter between the reduction projection optical system and the substrate stage in a laser processing device, it is possible to allow a laser to be incident on the reduction projection optical system even when laser processing of the substrate is not being performed, thereby suppressing temperature changes in the reduction projection optical system, and thereby suppressing a decrease in laser processing throughput and changes in processing position and processing accuracy, and thus completed the present invention.

[0038] That is, the present invention is a laser processing apparatus that includes a laser device that emits laser light, a reduction projection optical system, and a substrate stage, and that performs laser processing by irradiating a laser onto a substrate placed on the substrate stage, and that has a shutter between the reduction projection optical system and the substrate stage.

[0039] The present invention also provides a laser processing apparatus including the above laser processing apparatus, which irradiates a laser onto the substrate to process the shape of the surface of the substrate.

[0040] The present invention also provides a transfer device equipped with the above-mentioned laser processing device, which transfers an object to be transferred provided on a substrate to another substrate by irradiating the object with a laser through the substrate.

[0041] The present invention also provides a laser processing method for performing laser processing by irradiating a laser onto a substrate placed on a substrate stage using a laser processing device including a laser device that oscillates laser light, a reduction projection optical system, a substrate stage, and a shutter between the reduction projection optical system and the substrate stage, wherein the shutter is closed while the laser light is oscillated when the laser is not irradiated onto the substrate.

[0042] The present invention also provides a laser processing method using the above laser processing method, in which the laser processing is carried out to shape the surface of a substrate.

[0043] The present invention also provides a transfer method using the above laser processing method, in which a laser is irradiated onto an object provided on a substrate through the substrate, thereby transferring the object to another substrate.

[0044] The present invention will be described in detail below, but the present invention is not limited thereto.

[0045] [Laser Processing Apparatus] Fig. 1 is a schematic diagram showing an example of a laser processing apparatus of the present invention. As shown in Fig. 1, the laser processing apparatus 100 of the present invention is a laser processing apparatus 100 that includes a laser device 10 having a laser light source that oscillates a laser 1, a reduction projection optical system 50, and a substrate stage 60, and performs laser processing by irradiating a laser 5 onto a substrate 70 placed on the substrate stage 60. A shutter 80 is provided between the reduction projection optical system 50 and the substrate stage 60.

[0046] In this way, in the laser processing apparatus of the present invention having the shutter 80 closer to the substrate stage 60 than the reduction projection optical system 50, even when the shutter is closed and laser processing of the substrate 70 is not being performed, the laser can be kept in a state where it has reached the reduction projection optical system 50, and therefore the temperature of the reduction projection optical system 50 can be maintained at the same temperature as during laser processing of the substrate 70. This makes it possible to suppress the effects of dimensional changes in the reduction projection optical system 50 due to temperature changes in the reduction projection optical system 50, suppress a decrease in throughput of laser processing, and stabilize the processing position and processing accuracy.

[0047] The shutter 80 is not particularly limited as long as it can block or open the laser beam 5 passing through the reduction projection optical system 50. For example, it is preferable that the shutter 80 has an optical path changing member that forms an inclined surface with respect to the optical axis of the laser and can be arranged on the optical axis of the laser and removed from the optical axis of the laser. Such a shutter can easily block or open the laser optical path. Note that the means for placing the optical path changing member on the optical axis of the laser and removing it from the optical axis of the laser is not limited. It may be a means for blocking the laser optical path by linearly moving the optical path changing member to position it on the optical axis of the laser, or a means for blocking the laser optical path by changing the angle of the shutter within a shutter (optical path changing member) unit provided between the reduction projection optical system 50 and the substrate stage 60.

[0048] 1, the laser processing device 100 preferably includes a damper 90 that absorbs the laser energy on the switched laser optical path when the shutter 80 interrupts the laser optical axis and the laser optical path is switched, thereby improving safety and effectively suppressing damage to the device caused by the laser whose optical path has been switched.

[0049] (Laser Device) The laser device 10 that oscillates the laser 1 is not particularly limited, but may be, for example, a laser device (laser oscillator) that irradiates (emits) the laser 1 in a pulsed manner. More specifically, the laser device 10 shown in FIG. 1 may be equipped with an excimer laser oscillator. Use of an excimer laser enables highly productive processing. Furthermore, because excimer lasers have low coherence, use of an excimer laser makes it possible to achieve extremely uniform beam formation.

[0050] The irradiation shape of the laser 1 emitted by the laser device 10 is not particularly limited. For example, the irradiation shape may have an intensity distribution such that the laser intensity is greatest at the center (inner side) 1a and is lowest at the skirt (outer side) 1b, as shown in Fig. 8 .

[0051] (Reduction Projection Optical System) The laser processing device 100 shown in FIG. 1 is equipped with a reduction projection optical system 50, which allows the mask pattern formed on the photomask 30 to be enlarged larger than the processing pattern that is actually to be processed on the workpiece.

[0052] By enlarging the mask pattern formed on the photomask 30 more than the actual processing pattern, the energy of the laser 3 that strikes the photomask 30 can be made smaller than the actual processing energy. If the reduction magnification of the reduction projection optical system 50 is N, the laser energy that strikes the mask surface is 1 / (N ２ ) This makes it possible to suppress thermal drift due to the energy of the laser 3, thereby suppressing thermal expansion of the photomask 30 and enabling high-precision processing even after a long period of processing operation.

[0053] Furthermore, deterioration of optical components (for example, the optical system 20 and the photomask 30) due to the heat of the laser can be suppressed, and the life of the optical components can be extended.

[0054] The reduction projection optical system 50 can include a pair of reduction projection lenses. When the reduction projection optical system 50 is an infinity optical system, the magnification achieved by the reduction projection optical system 50 can be adjusted, for example, by adjusting the ratio of the focal lengths of the reduction projection lenses and the distance between the reduction projection lenses.

[0055] The NA of the reduction projection lens is preferably selected in accordance with the energy density and processing resolution required for processing the substrate 70. The NA of the reduction projection lens is preferably 0.12 or greater. In the present invention, even if laser processing is performed with a high NA to form high resolution, it is possible to prevent the recesses and / or through holes formed from having a tapered shape.

[0056] The laser processing apparatus 100 of the present invention preferably further comprises a temperature adjusting means for adjusting the temperature of the reduction projection optical system 50 .

[0057] By providing a temperature adjusting means, it is possible to further suppress the influence of heat due to the laser energy in the reduction projection optical system 50. As described above, in the reduction projection optical system 50, the laser 4 that has passed through the photomask 30 is reduced and projected at 1 / N, so the energy of the laser that passes through the lens portion at the tip of the objective is N times smaller than the energy of the laser that is irradiated onto the photomask 30. ２ Therefore, by providing the reduction projection optical system 50 with a temperature control function in order to suppress this thermal energy, it is possible to suppress the thermal drift caused by the laser energy, and it becomes possible to perform high-precision processing even after a long-term processing operation.

[0058] Furthermore, in the laser processing method and laser processing apparatus 100 of the present invention, by synchronously operating the photomask 30 and the substrate stage 60 and fixing the position of the laser beam during substrate processing, it is possible to use a reduction projection lens with a very small diameter. The temperature control means for the reduction projection lens is not directly attached to the lens itself, but rather cools the jacket portion that holds the lens. Therefore, when the lens diameter is large, while temperature control can be achieved around the periphery of the lens, the temperature control effect is less likely to spread to the crucial central portion, making heat management difficult. As a result, even a small amount of energy absorbed into the lens due to long-term laser irradiation can easily cause thermal distortion. If the laser processing apparatus 100 has a temperature control function for the reduction projection optical system 50, the lens diameter can be reduced, thereby preventing such problems.

[0059] Furthermore, it is possible to prevent defects caused by laser irradiation of the reduction projection optical system 50 and extend its life.

[0060] (Optical System) As shown in Fig. 1, the laser processing device 100 according to the present invention may include an optical system 20 that shapes the irradiation shape of the laser 1. In the example of the laser processing device 100 shown in Fig. 1, the optical system 20 may include a prism 21 that changes the irradiation shape of the intensity distribution of the laser 1, and a shaping optical system 22 that further shapes the irradiation shape of the laser 2 from the prism 21.

[0061] Furthermore, the laser beam 3 may include a photomask 30 that shapes the laser beam 3 shaped by the optical system 20 into a desired pattern, and a folding mirror 40 that changes the optical axis of the laser beam 4 from the photomask 30. The shaping of the laser beam irradiation shape by the optical system 20 and the photomask 30 will be described in detail in the explanation of laser processing.

[0062] The optical system 20, the photomask 30, and the folding mirror 40 are optional components for the laser processing apparatus 100 of the present invention.

[0063] The laser processing device 100 may further include a controller for controlling each part or the entire device. In particular, the device may be controllable to perform a laser processing method described below. Note that the laser processing device 100 shown in FIG. 1 is an example of the laser processing device of the present invention, but the laser processing device of the present invention is not limited to the device shown in FIG.

[0064] [Laser Processing Method] A laser processing method according to the present invention uses a laser processing device 100, as shown in FIG. 1 , which includes a laser device 10 that oscillates laser light, a reduction projection optical system 50, a substrate stage 60, and a shutter 80 between the reduction projection optical system 50 and the substrate stage 60, to perform laser processing by irradiating a laser onto a substrate 70 placed on the substrate stage 60, and is characterized in that when the laser is not irradiating the substrate 70, the shutter 80 is closed while the laser light is oscillating.

[0065] According to the laser processing method of the present invention, when laser processing of a substrate is not being performed, the shutter can be closed to allow the laser to reach the reduction projection optical system 50, thereby maintaining the temperature of the reduction projection optical system 50 at the same temperature as during laser processing of the substrate 70. Since the effects of dimensional changes in the reduction projection optical system 50 due to temperature changes in the reduction projection optical system 50 can be suppressed, laser processing can be resumed simply by removing the shutter from the optical path when laser processing of the substrate 70 is resumed, thereby suppressing a decrease in laser processing throughput. Furthermore, since the shape and position of the laser irradiation can be stabilized, stable laser processing can always be performed regardless of the interval between laser processing.

[0066] It is also preferable to use a shutter 80 that has an optical path changing member that forms an inclined surface with respect to the optical axis of the laser light and that can be placed on the optical axis of the laser and removed from the optical axis of the laser. In this way, the laser optical path can be easily blocked or opened.

[0067] It is also preferable to switch the optical path of the laser by closing the shutter 80, and absorb the laser energy with a damper 90 arranged on the optical path of the switched laser. This can increase safety and effectively prevent damage to the device caused by the laser whose optical path has been switched.

[0068] [Laser Processing Apparatus] The laser processing apparatus according to the present invention may be a laser processing apparatus that irradiates a substrate with a laser to shape the surface of the substrate. Examples of shape processing of the substrate surface include processing to form recesses or through holes in the substrate surface. Specific examples include processing to form wiring grooves or via holes in the surface of a substrate used in a semiconductor package substrate. In the following description, descriptions of configurations similar to those of the laser processing apparatus described above may be omitted.

[0069] A specific embodiment of the laser processing apparatus according to the present invention is shown in FIG. 2. As shown in FIG. 2, the laser processing apparatus 100A according to the present invention has a shutter 80 located closer to the substrate stage 60 than the reduction projection optical system 50. With this laser processing apparatus according to the present invention, the shutter can be closed when laser processing of the substrate is not being performed, allowing the laser to reach the reduction projection optical system 50. This makes it possible to maintain the temperature of the reduction projection optical system 50 at the same temperature as when laser processing of the substrate was being performed. When laser processing of the substrate is to be resumed, laser processing can be resumed simply by removing the shutter from the optical path. This makes it possible to suppress the effects of changes in positional accuracy and dimensional changes caused by temperature changes in the reduction projection optical system 50, thereby suppressing a decrease in laser processing throughput.

[0070] (Laser Device) The laser 1 is not particularly limited, but for example, an excimer laser can be used. By using an excimer laser, it is possible to efficiently process a workpiece made of an organic material, such as an ABF substrate, and to achieve highly productive processing. Furthermore, because the excimer laser has low coherence, it is possible to achieve extremely uniform beam formation by using an excimer laser.

[0071] Furthermore, the use of an excimer laser allows for more precise adjustment of the processing depth and the width of the recesses and / or through holes than solid-state lasers. Excimer lasers are particularly useful for forming recesses such as fastening holes and trenches. Therefore, the use of an excimer laser allows for highly accurate processing of complex concave and convex shapes, such as circuit boards.

[0072] The irradiation shape of the laser 1 emitted by the laser device 10 is not particularly limited. For example, the irradiation shape may have an intensity distribution such that the laser intensity is greatest at the center (inner side) 1a and is lowest at the skirt (outer side) 1b, as shown in Fig. 8 .

[0073] 2 is equipped with a reduction projection optical system 50, which enlarges the mask pattern formed on the photomask 30 to be larger than the processing pattern to be actually formed on the workpiece. The reduction projection optical system of the laser processing apparatus 100A is the same as the reduction projection optical system described in the laser processing apparatus.

[0074] (Optical System) As shown in FIG. 2 , the laser processing apparatus 100A according to the present invention may include an optical system 20 that changes the laser intensity distribution on the processing surface of the substrate 70 so that the intensity of the laser is greater in the outer portion of the intensity distribution than in the inner portion. In the example of the laser processing apparatus 100A shown in FIG. 2 , the optical system 20 may include a prism 21 and a shaping optical system 22. As will be described in detail below, the prism 21 converts a laser having an intensity distribution in which the laser intensity is greatest in the center and smaller at the base into a laser having an irradiation shape in which the intensity of the outer portion of the laser intensity distribution is greater than the intensity of the inner portion. The shaping optical system 22 converts the laser irradiation shape converted by the prism 21 into a top-hat irradiation shape. In the laser processing apparatus 100A shown in FIG. 2 , the prism 21 includes a roof prism, but may also include a conical prism.

[0075] 2 may further include a photomask 30 and a folding mirror 40 in this order in the optical path of the laser processing apparatus 100A from the optical system 20 to the substrate 70. The laser processing apparatus 100A may further include a controller that controls each part of the apparatus or the entire apparatus.

[0076] The optical system 20, the photomask 30, the folding mirror 40, and the controller 300 are optional components in the laser processing apparatus 100A of the present invention.

[0077] 2, the laser processing apparatus 100A may include a mask alignment camera 31 as an imaging means for reading characteristic portions of the photomask 30, and a workpiece alignment camera 61 as an imaging means for reading characteristic portions of the substrate 70. The mask alignment camera 31 is configured to send position information of the characteristic portions of the photomask 30 to the controller 300. The workpiece alignment camera 61 is configured to send position information of the characteristic portions of the substrate 70 to the controller 300. The controller 300 is configured to adjust the relative positions of the substrate 70 and the photomask 30 based on this position information. In another aspect, the controller 300 can be configured to synchronously move the substrate 70 and the photomask 30 placed on the stage 60.

[0078] [Laser Processing Method] The laser processing method of the present invention can be carried out using, for example, the laser processing apparatus of the present invention, but can also be carried out using an apparatus other than the laser processing apparatus of the present invention.

[0079] The laser processing method of the present invention is a laser processing method for shaping the surface of a substrate 70 using a laser. Examples of shaping the surface of a substrate include processes for forming recesses and through holes in the surface of the substrate. Specific examples include processes for forming wiring grooves and via holes in the surface of a substrate used in a semiconductor package substrate.

[0080] According to the laser processing method of the present invention, when laser processing of a substrate is not being performed, the shutter can be closed to allow the laser to reach the reduction projection optical system 50, thereby maintaining the temperature of the reduction projection optical system 50 at the same temperature as when laser processing of the substrate is being performed. Since the effects of dimensional changes in the reduction projection optical system 50 due to temperature changes in the reduction projection optical system 50 can be suppressed, laser processing can be resumed simply by removing the shutter from the optical path when laser processing of the substrate is resumed, thereby suppressing a decrease in laser processing throughput. Furthermore, since the shape and position of the laser irradiation can be stabilized, stable processing can be performed at all times regardless of the laser processing interval.

[0081] Hereinafter, a specific description will be given of one embodiment of the laser processing method of the present invention that can be performed using the laser processing apparatus 100A shown in FIG.

[0082] Optional aspects of the laser processing method and laser processing apparatus of the present invention will be described below, but the present invention is not limited to the examples described below.

[0083] The substrate 70 that is the object of laser processing in the present invention is not particularly limited, but may be, for example, a semiconductor package substrate.

[0084] In the laser processing of one embodiment of the present invention, processing can be performed by setting the laser intensity distribution on the processing surface of the substrate 70 to an irradiation shape in which the intensity of the outer part of the intensity distribution is greater than the intensity of the inner part. Such a laser processing method will be described by way of example with reference to Figures 2 to 5.

[0085] First, as shown in Fig. 2, a laser 1 having the irradiation shape shown in Fig. 2(a) is emitted from a laser device 10. In this example, the irradiation shape of the laser 1 is a shape in which the laser intensity at the inner portion 1a is greater than the laser intensity at the outer portion 1b, as shown in Fig. 3. In another aspect, the irradiation shape of the laser 1 has an intensity distribution in which the laser intensity at the center (inner portion) 1a is greatest and the laser intensity at the skirt (outer portion) 1b is smaller.

[0086] Next, the laser 1 is incident on a prism 21 of the optical system 20. The prism 21 converts the laser 1 into a laser 2 having an irradiation shape (FIG. 2(b)) in which the intensity of the outer portion of the intensity distribution of the laser 1 is greater than the intensity of the inner portion. FIG. 2 shows a prism 21 made up of four (two pairs of) roof prisms as an example of the prism 21. Note that FIG. 3 shows only two roof prisms 21a and 21b of the laser 1 that are involved in the irradiation shape of the surface parallel to the paper surface.

[0087] The prism 21 is not limited to a roof prism, and may be, for example, a conical prism.

[0088] Next, the laser 2, which is emitted from the prism 21 and has the irradiation shape shown in Figures 2(b) and 3, enters the shaping optical system 22. As shown in Figure 3, the shaping optical system 22 focuses each component of the laser 2 toward the image formation point F1, and shapes the irradiation shape of the laser 2 into a top-hat irradiation shape shown in Figure 2(c), which becomes the laser 3.

[0089] The laser 3 is incident on the photomask 30 located at the position of the image forming point F1. The photomask 30 has a mask pattern corresponding to the pattern to be processed on the substrate 70. By scanning and irradiating the laser onto the substrate 70 via the photomask 30, recesses and / or through holes can be formed in the substrate 70 in the desired pattern.

[0090] The laser 4 emitted from the photomask 30 and having the irradiation shape (top hat shape) shown in Fig. 2(d) is redirected by a folding mirror 40 and enters a reduction projection optical system (projection lens) 50. The effect of using the reduction projection optical system 50 will be described later.

[0091] 3, the laser beam 5 emitted from the reduction projection optical system 50 reaches the surface (initial processing surface) 71 of the substrate 70. In FIG. 3, an example is shown in which the image forming point F2 of the reduction projection optical system 50 is aligned with the surface 71 of the substrate 70. However, the image forming point F2 of the reduction projection optical system 50 is not limited to the surface 71 of the substrate 70.

[0092] As shown in Fig. 3, the irradiation shape of the laser 5 irradiated onto the surface 71 of the substrate 70 is a top hat shape as shown in Fig. 2(e). On the other hand, at the surface 72 to be processed, which is processed further from the image point F2, the intensity distribution of the laser 6 is set to an irradiation shape in which the intensity of the outer portion 6b of the intensity distribution is greater than the intensity of the inner portion 6a, as shown in Fig. 3.

[0093] 2 and 3, as shown in outline in Figures 4(a) to 4(e), the further away from the image formation point F2 (under focus U), the closer the irradiation shape of the laser 6 becomes to the irradiation shape of the laser 2 before shaping by the shaping optical system 22. This is the reason why the intensity distribution of the laser 6 has a greater intensity in the outer portion 6b of the intensity distribution than in the inner portion 6a.

[0094] By performing processing on the workpiece surface 72 by setting the intensity distribution of the laser 6 to an irradiation shape in which the intensity of the outer portion 6b of the intensity distribution is greater than the intensity of the inner portion 6a, as shown schematically in FIG. 5 , it is possible to prevent the recesses 200 from tapering. By continuing processing, it is possible to form through holes with reduced tapering. Furthermore, the laser processing method of this embodiment can prevent the recesses and / or through holes from tapering in this way, allowing for the formation of high-resolution, complex patterns. Furthermore, the laser processing method of this embodiment can prevent the recesses 200 and / or through holes from tapering, even when forming recesses and / or through holes with high resolution.

[0095] In the laser processing method of this embodiment, processing can be performed on at least a portion of a workpiece surface 72 of a substrate 70 using a laser having an irradiation shape in which the intensity of an outer portion 6 b is greater than the intensity of an inner portion 6 a. For example, as shown in the examples of FIGS. 2 and 3 , a surface (initial workpiece surface) 71 of the substrate 70 may be processed using a laser 5 having a top-hat irradiation shape.

[0096] In this embodiment, as shown in FIG. 5, for example, as the processing progresses in the depth direction of the substrate 70, the shape of the intensity distribution of the laser 6 on the processing surface 72 of the substrate 70 can be changed to perform processing.

[0097] From another perspective, the example of Figure 5 can also be said to be an example of processing in which the shape of the intensity distribution of the laser 6 is changed so that the intensity of the outer portion 6b in the intensity distribution of the laser 6 becomes greater than the intensity of the inner portion 6a as processing progresses in the depth direction of the substrate 70.

[0098] By carrying out the processing in this manner, it is possible to more reliably prevent the recesses and / or through holes to be formed from having a tapered shape, and it is therefore possible to more reliably form highly precise and complex patterns.

[0099] However, in this embodiment, processing can be performed by setting the intensity distribution of the laser 6 on at least one workpiece surface 72 of the substrate 70 to an irradiation shape in which the intensity of the outer portion 6 a of the intensity distribution is greater than the intensity of the inner portion 6 b, and there is no need to continuously change the laser intensity distribution.

[0100] In the present invention, a photomask 30 can also be used to form a pattern of predetermined recesses and / or through holes. Even when the photomask 30 is used, the intensity distribution of the laser 6 on the processing surface 72 of the substrate 70 can be shaped so that the intensity of the outer portion 6b of the intensity distribution is greater than the intensity of the inner portion 6a. This prevents the recesses and / or through holes from becoming tapered, thereby enabling the formation of highly precise and complex patterns. Alternatively, as shown in FIG. 6, the present invention does not require the use of the photomask 30.

[0101] Another aspect of the present invention, which has been described with reference to FIGS. 2 to 5 , can also be seen as a laser processing method for forming recesses and / or through holes in a substrate 70 using a laser, which uses an optical system 20 that shapes the irradiation shape of a laser 2, which has a shape in which the intensity of the outer portion is greater than the intensity of the inner portion in the laser intensity distribution, into a top-hat irradiation shape.

[0102] By laser processing the substrate 70 using such an optical system 20, at least a portion of the substrate 70 away from the surface can be processed with an irradiation shape of the laser 6 in which the intensity of the outer portion 6b is greater than the intensity of the inner portion 6a. With this laser processing method, even when recesses are formed with high resolution, the width of the bottom of the recess can be prevented from being smaller than the width of the opening of the recess on the initial processing surface 71. Furthermore, with this laser processing method, even when through holes are formed with high resolution, the width of the opening at the lower end of the through hole can be prevented from being smaller than the width of the upper end of the through hole. In other words, with the laser processing method of this embodiment expressed in this aspect, even when recesses and / or through holes are formed with high resolution, the recesses and / or through holes formed can be prevented from having a tapered shape, thereby enabling the formation of high-resolution, complex patterns.

[0103] In particular, when processing semiconductor package substrates, there are processing patterns that include a mixture of through holes, recesses, for example, via processing and groove processing. In this case, the method of this embodiment allows processing in the same process without separating the via processing and groove processing steps. Furthermore, semiconductor package substrates are becoming increasingly dense, and while the conventional laser drill method for via processing increases the processing time due to the increased number of holes drilled as a result of higher density, this method does not increase the processing time due to the increased number of holes drilled or the higher resolution of the pattern.

[0104] According to another embodiment of the laser processing method of the present invention, for example, ablation processing can be performed on the substrate 70. In the case of ablation processing, the laser settings can be freely set within the range in which the substrate 70 absorbs the energy of the lasers 5 and 6, within the wavelength and energy density that allow ablation processing.

[0105] As described above, according to one embodiment of the present invention, it is possible to form a pattern of highly precise recesses and / or through holes. Specifically, according to one embodiment of the present invention, it is possible to form recesses and / or through holes having a width of, for example, 20 μm or less and in which tapering is suppressed.

[0106] Furthermore, the recesses and / or through holes that can be formed in one embodiment of the present invention can have a depth of, for example, 20 μm or less. Note that recesses can be formed by making the processing depth smaller than the thickness of the substrate 70, and through holes can be formed by making the processing depth the same as the thickness of the substrate 70.

[0107] In another aspect, according to one embodiment of the present invention, a pattern of recesses and / or through holes with a high aspect ratio can be formed. According to one embodiment of the present invention, for example, a recess having a ratio of the height of the processed portion to the width of the bottom of the recess of 1.0 or more can be formed. Furthermore, according to the present invention, for example, a recess having a ratio of the height of the processed portion to the width of the lower end opening of a through hole of 1.0 or more can be formed.

[0108] In yet another aspect, according to one embodiment of the present invention, it is possible to form, for example, a recess whose bottom width is 70% or more of the opening width of the recess on the initial processing surface of the workpiece, and / or a through hole whose lower opening width is 70% or more of the width of the upper opening width of the through hole on the initial processing surface of the workpiece.

[0109] Furthermore, in one embodiment of the present invention, since recesses can be formed while suppressing tapering, it is also possible to form a plurality of recesses 200 and set the distance 202 between the bottoms of adjacent recesses 200 to 110% or less of the width 201 of the bottoms, as shown in Figure 7. Therefore, in one embodiment of the present invention, a plurality of recesses 200 can be formed at high density.

[0110] <Scanning Irradiation> In the present invention, processing may be performed while the lasers 5 and 6 are scanned relatively to the surface 71 to be processed. That is, the laser processing of the present invention may be performed as scanning processing.

[0111] By performing the scan processing, it is possible to perform laser processing with high precision even on a substrate 70 having a large area.

[0112] Furthermore, by performing the scan processing, it is possible to prevent an increase in processing time even if the density of recesses and / or through holes to be processed increases.

[0113] The scanning process can be performed by, for example, moving the substrate 70 placed on the stage 60 and the photomask 30 in synchronization.

[0114] By doing so, laser processing can be performed without moving the lasers 1 to 6 themselves.

[0115] Furthermore, in this embodiment, the processing area is not limited to the area of ​​the lens, so an area (angle of view) larger than the area of ​​the lens can be processed.

[0116] According to this embodiment, the reduction projection optical system 50 required for irradiation can be made small, and the laser irradiation position accuracy and temperature controllability can be improved. Furthermore, since the reduction projection optical system 50, which will be described below, can be made small, image distortion due to irradiation is also reduced.

[0117] In the laser processing apparatus 100A shown in FIG. 2, the controller 300 can be used to move the substrate 70 placed on the stage 60 and the photomask 30 in synchronization.

[0118] More specifically, the controller 300 is configured to align the relative positions of the substrate 70 and the photomask 30 based on the positional information of the characteristic parts of the mask 30 obtained by the mask alignment camera 31 and the positional information of the characteristic parts of the substrate 70 obtained by the workpiece alignment camera 61.

[0119] [Transfer Apparatus] The transfer apparatus according to the present invention may be an apparatus that irradiates a laser beam onto the interface between a substrate (first substrate) having a transfer object thereon, thereby peeling the transfer object from the first substrate (laser lift-off: Laser Lift-OFF (LLO)), and transferring the peeled transfer object to another substrate (second substrate). Known laser lift-off methods include gap laser lift-off (Gap-LLO) and contact laser lift-off (Contact-LLO).

[0120] Fig. 9 shows a schematic diagram of one embodiment of the transfer apparatus of the present invention. The transfer apparatus 100B shown in Fig. 9 is an apparatus configured to perform Gap-LLO. The transfer apparatus 100B includes a laser device (laser oscillator) 110, a substrate stage 160, a reduction projection optical system 150, and a shutter 80 between the reduction projection optical system 150 and the substrate stage 160.

[0121] The transfer device of the present invention can close the shutter when not transferring an object to allow the laser to reach the reduction projection optical system 150, thereby maintaining the temperature of the reduction projection optical system 150 at the same temperature as when transferring an object to be transferred. Since the effect of dimensional changes in the reduction projection optical system 150 due to temperature changes in the reduction projection optical system 150 can be suppressed, transfer of the object to be transferred can be resumed simply by removing the shutter from the optical path when laser processing of the substrate is resumed, and a decrease in throughput of transferring the object to be transferred can be suppressed.

[0122] The transfer device 100B further includes, as optional components, a shaping optical system 120, a photomask 130, a folding mirror 140, an alignment camera 170, and a controller 300. Hereinafter, a description of components common to the above-described laser processing device and laser processing device may be omitted.

[0123] The substrate stage 160 is composed of an upper stage 161 having an opening 161a and supporting the first substrate 70A, and a lower stage 162 supporting the second substrate 70B. The first substrate 70A may be equipped with a plurality of transfer objects 75. The substrate stage 160 can be configured to support the first substrate 70A and the second substrate 70B facing each other.

[0124] The laser device 110 is configured to oscillate a laser 1. In the transfer device 100B, the laser 1 oscillated from the laser device 110 passes through a shaping optical system 120 to be shaped into a laser 3, the laser 3 passes through a photomask 130 to be shaped into a laser 4, the laser 4 has its direction of travel changed by a folding mirror 140, and further passes through a reduction projection optical system 150 to become a laser 5, and this laser 5 passes through an opening 161a of an upper stage 161 to form an optical path that reaches the first substrate 70A. In other words, the photomask 130 is disposed between the optical path between the laser device 110 and the substrate stage 160.

[0125] In the transfer device 100B shown in Figure 9, the laser device 110, the photomask 130, and the substrate stage 160 (upper stage 161 and lower stage 162) are configured to irradiate the laser from the laser device 110 simultaneously onto the interface between multiple transfer objects 75 and the first substrate 70A.

[0126] The laser emitted from the laser device 110 and its optical path will be described below.

[0127] The laser 1 emitted from the laser device 110 can be, for example, an excimer laser.

[0128] The optional shaping optical system 120 shapes the irradiation shape of the laser 1 emitted from the laser device 110, for example, as shown in Fig. 9(a), into a rectangular irradiation shape as shown in Fig. 9(b), for example, and emits it as a laser 3. The laser 3 having a rectangular irradiation shape can exhibit a uniform irradiation energy density, for example, a beam profile exhibiting a top hat shape. However, the laser shaping by the shaping optical system 120 is not limited to this.

[0129] The photomask 130 is configured to shape the irradiation shape of the incident laser 3 into a pattern as shown in FIG. 9( c) and emit it as a laser 4. More specifically, the photomask 130 has a pattern that shapes the laser from the laser device 110 into a shape that irradiates only a portion of the interface with the first substrate 70A of each of the multiple transfer objects 75. Furthermore, the photomask 130 is configured to irradiate the received laser simultaneously onto the interface with the first substrate 70A of each of the multiple transfer objects 75, and can also be said to have a pattern that shapes the laser so that only a portion of the interface with the first substrate 70A of each of the multiple transfer objects 75 becomes an irradiation area.

[0130] The photomask 130 may further have a pattern formed into a shape that irradiates the entire surface of the interface between the first substrate 70A and each of the multiple transfer objects 75. Other details of the photomask 130 will be described later.

[0131] The laser beam 4 emitted from the photomask 130 has its direction of travel changed by a folding mirror 140 and enters a reduction projection optical system 150. The reduction projection optical system 150 reduces the irradiation shape of the incident laser beam 4, for example, from that shown in FIG. 9(d) to that shown in FIG. 9(e), and emits the laser beam 5.

[0132] By incorporating the reduction projection optical system 150 into the optical path, the energy of the laser 20b incident on the photomask 130 can be made smaller than the energy required to peel the transfer object 75 from the first substrate 70A. If the reduction magnification of the reduction projection optical system 150 is N, the energy of the laser 3 incident on the photomask 130 is 1 / (N ２) This prevents deterioration of the shaping optical system 120 and the photomask 130 due to laser irradiation, and also suppresses thermal drift due to the energy of the laser 3, thereby suppressing thermal expansion of the photomask 130 and enabling highly accurate transfer even after a long period of laser lift-off. Furthermore, deterioration of the photomask 130 can be suppressed, thereby extending its lifespan. Also, the thickness of the light-shielding material of the photomask can be made thin, for example, to 1000 Å or less.

[0133] The alignment camera 170 and the controller 300 are configured to monitor the laser irradiation area on the first substrate 70A and to control the laser device 110, the photomask 130, and the stage 160 (upper stage 161 and lower stage 162). The controller 300 can, for example, move the photomask 130 to change the position of the pattern on the photomask 130 relative to the optical path of the laser 5. The controller 300 can also move and / or rotate the upper stage 161 on the same plane to change the position of the first substrate 70A, particularly the position of the transfer object 75, relative to the optical path of the laser 5. The controller 300 can also move and / or rotate the lower stage 162 on the same plane to change the position of the second substrate 70B relative to the optical path of the laser 5.

[0134] In the laser lift-off apparatus 100B shown in FIG. 9, the laser device 110, the photomask 130, the alignment camera 170, the upper stage 161, and the lower stage 162 are each electrically connected to a controller 300.

[0135] The controller 300 can control the laser lift-off apparatus 100B to perform the laser lift-off method of the present invention as described below.

[0136] The transfer device 100B of the present invention is not limited to a device that performs Gap-LLO as shown in FIG. 9, but may also be a device that performs Contact-LLO.

[0137] FIG. 10 is a schematic diagram of a second embodiment of the transfer device of the present invention. The transfer device 100C shown in FIG. 10 is an apparatus configured to perform Contact-LLO. The transfer device 100C shown in FIG. 10 is identical to the transfer device 100B shown in FIG. 9 except that a substrate stage 160 having an opening 160a supports a first substrate 70A and a second substrate 70B in a state in which a transfer target 75 on the first substrate 70A is in contact with the second substrate 70B.

[0138] [Transfer Method] The transfer method of the present invention is a transfer method in which a transfer object provided on a substrate is transferred to another substrate by irradiating the transfer object on the substrate with a laser through the substrate using the laser processing method of the present invention. The transfer method of the present invention can be performed using the transfer device 100B shown in Fig. 9, but is not limited to this, and can also be performed using the transfer device 100C shown in Fig. 10 or other devices.

[0139] According to the transfer method of the present invention, when an object is not being transferred, the shutter 80 can be closed to allow the laser to reach the reduction projection optical system 150, so that the temperature of the reduction projection optical system 150 can be maintained at the same temperature as when the object was being transferred. Since the effect of dimensional changes in the reduction projection optical system 150 due to temperature changes in the reduction projection optical system 150 can be suppressed, transfer of the object can be resumed simply by removing the shutter from the optical path when transferring the object again, which suppresses a decrease in throughput of transferring the object, and allows the object to be transferred reliably and in a stable position without causing defects such as breakage or cracks.

[0140] Hereinafter, as one embodiment of the transfer method of the present invention, an example of the transfer method of the present invention that can be performed using the transfer device 100B shown in FIG. 9 will be specifically described.

[0141] The transfer method of the present invention includes a batch transfer process using partial irradiation, which will be described below with reference to FIG.

[0142] Fig. 11(a) is a schematic cross-sectional view showing the concept of laser irradiation in a batch transfer step in an example of the transfer method of the present invention, and Fig. 11(b) is a diagram showing the positional relationship between a photomask pattern and one transfer object during the laser irradiation shown in Fig. 11(a).

[0143] In this example, a laser beam 1 emitted from a laser device (laser oscillator) 110 shown in Fig. 9 is shaped by a shaping optical system 120 to become a laser beam 3. This laser beam 3 is incident on a photomask 130 shown in Figs. 11(a) and 11(b).

[0144] 11(a) and 11(b) includes a laser-transmitting substrate 131 and a pattern-forming layer 132 formed on the substrate 131. As shown in FIG. 11(b), a pattern 31 including a plurality of openings 132a is formed in the pattern-forming layer 132.

[0145] Since portions of the pattern formation layer 132 other than the openings 132a block the laser, only the component of the laser 3 incident on the photomask 130 that passes through the portion corresponding to the openings 132a is transmitted through the photomask 130. As a result, a laser having an irradiation shape with a pattern 31 (laser 4 shown in FIG. 9) is emitted from the photomask 130. Next, although not shown in FIG. 11, the laser 4 is incident on the reduction projection optical system 150 shown in FIG. 9. In the reduction projection optical system 150, the laser 4 is reduced while maintaining the irradiation shape of the pattern 31 shown in FIG. 11(b), and is emitted as laser 5.

[0146] When the shutter 80 is open, the laser 5 emitted from the reduction projection optical system 150 is incident on the surface of the first substrate 70A opposite to the object 75 to be transferred. The laser 5 passes through the first substrate 70A and reaches the interface 76 between the first substrate 70A and the object 75 to be transferred.

[0147] Here, the term "interface" does not mean a strict boundary surface, but rather a region that is decomposed or the like by laser irradiation. Therefore, it can also be referred to as an ablation layer. Specifically, this term includes a form in which at least a portion of the side of the first substrate 70A on which the transfer object 75 is provided is an ablation layer, a form in which an ablation layer is formed on the side of the first substrate 70A on which the transfer object 75 is provided, a form in which at least a portion of the transfer object 75 on the first substrate 70A side is an ablation layer, a form in which an ablation layer is formed on the transfer object 75 on the first substrate 70A side, and a form in which an ablation layer is located between the first substrate 70A and the transfer object 75. In addition, even if a portion of the first substrate 70A or the transfer object 75 is an ablation layer, an ablation layer may be provided separately from the first substrate 70A or the transfer object 75.

[0148] 11 shows only one transfer object 75, but in the transfer method of this embodiment, in the batch transfer step, the laser 5 is irradiated simultaneously onto interfaces 76 between multiple transfer objects 75 and the first substrate 70A. However, the multiple transfer objects 75 do not necessarily have to be adjacent to each other, and may be, for example, multiple transfer objects 75 that are not adjacent to each other but are arranged apart from each other.

[0149] As described above, the laser 5 has an irradiation shape that includes the pattern 31 of the photomask 130. Therefore, as shown in Figures 11(a) and 11(b), the laser 5 is irradiated only to a portion 76a of the interface 76 between each of the multiple transfer objects 75 and the first substrate 70A, rather than to the entire interface 76. In other words, in the laser lift-off method of the present invention, in the batch transfer step, the laser 5 is irradiated only to a portion 76a of the interface 76 between each of the multiple transfer objects 75 and the first substrate 70A (partial irradiation).

[0150] In the batch transfer process, the plurality of transfer objects 75 are partially irradiated with the laser 5 in this manner, thereby peeling the plurality of transfer objects 75 off from the first substrate 70A.

[0151] The energy required for delamination is energy that can weaken the bonding force (e.g., adhesive force or joining force) between the transfer target 75 and the first substrate 70A, thereby separating the transfer target 75 and the first substrate 70A. For example, if a GaN layer is present at the interface between the transfer target 75 and the first substrate 70A, the GaN layer must be decomposed (ablated) in order to delaminate the transfer target 75. This requires a high laser energy density. Furthermore, nitrogen gas is generated by the decomposition of the GaN layer. The pressure of the generated nitrogen gas acts as a driving force, and the transfer target 75, having been decomposed from the first substrate 70A, moves to the second substrate 70B. This achieves transfer.

[0152] GaN is difficult to decompose, but decomposes rapidly when an energy threshold is exceeded. Therefore, in the batch transfer process, if a laser is irradiated onto the entire surface of the interface 76 of each of the multiple transfer objects 75 with the first substrate 70A with enough energy to achieve separation between the transfer objects 75 and the first substrate 70A, a large amount of nitrogen gas is rapidly generated, and the ejection vector of the generated gas becomes too large. As a result, the transfer objects 75 that have been peeled off from the first substrate 70A are subjected to excessive pressure or have an initial velocity that is too high, causing them to collide with the surface of the second substrate 70B with a very large ejection force as they move from the first substrate 70A to the second substrate 70B. As a result, the transfer objects 75 are prone to cracking while moving from the first substrate 70A to the second substrate 70B, or to cracking or chipping when they reach the second substrate 70B. Furthermore, an excessively large ejection vector makes it difficult to control the movement of the transfer object 75 to the second substrate 70B, making it more likely that unintended positional deviations will occur when transferring the transfer object 75 to the second substrate 70B.

[0153] In contrast, in the transfer method of the present invention, as described above, by partially irradiating the laser 5 onto only a portion of the interface 76 of multiple transfer objects 75 in the batch transfer process, the amount of gas generated when the multiple transfer objects 75 are peeled from the first substrate 70A is reduced, and the pressure experienced by the transfer objects 75 peeled from the first substrate 70A can be reduced. As a result, the propulsive force applied to the transfer objects 75 peeled from the first substrate 70A is appropriately suppressed, and the impact caused by contact between the transfer objects 75 and the second substrate 70B can be reduced. Furthermore, the peeled transfer objects 75 can be moved straight from the first substrate 70A to the second substrate 70B, achieving a lift-off process with high transfer position accuracy.

[0154] The above description uses an example in which the GaN layer decomposes during delamination. However, because delamination by laser lift-off is based on ablation, the problem of the ejection vector becoming too large inevitably occurs when full-surface irradiation is used, as described above. On the other hand, in the laser lift-off method of this embodiment, partial irradiation is performed in the batch transfer process, thereby minimizing the ejection vector. Therefore, regardless of the combination of the first substrate 70A and the transfer object 75, the transfer object 75 can be transferred while preventing damage such as cracking or chipping of the transfer object 75. Furthermore, although the application of partial irradiation to laser lift-off using ablation has been described here, even in transfer methods that do not use ablation but impart a propulsive force to the transfer object by laser irradiation, partial laser irradiation can alleviate the propulsive force, leading to improved transfer accuracy.

[0155] Furthermore, even in transfer by the Contact-LLO method using the transfer device 100C shown in Fig. 10, in the case of full-surface irradiation, cracks and chips may occur due to the ejection vector becoming too large, as described above. According to the transfer method of the present invention, even in the Contact-LLO method, the transfer object 75 can be transferred while preventing damage such as cracks and chips to the transfer object 75.

[0156] Furthermore, in the case where decomposition products are generated by laser irradiation, the amount of the products generated can be reduced, and the subsequent cleaning process can be simplified.

[0157] [Transfer Object] The transfer object in the transfer method of the present invention is not particularly limited. For example, the transfer object may be selected from the group consisting of a semiconductor chip, an LED chip, a resin material film, and an inorganic film. The resin material film may contain an inorganic material. Furthermore, the resin material film may have a multilayer structure, and the multiple films constituting the multilayer structure may consist solely of resin material films or may be a combination of resin material films and inorganic material films.

[0158] When a thin object to be transferred, with a thickness of 1 to 10 μm, is irradiated over its entire surface using a conventional laser lift-off method, the object is more likely to be damaged during laser lift-off if its longitudinal dimension or area is large. Specifically, when a thin object to be transferred, with a longitudinal dimension of 80 μm or more, or an area of ​​6,400 μm, is irradiated over its entire surface using a conventional laser lift-off method, the object is more likely to be damaged during laser lift-off. ２ In the case of the above-mentioned transfer objects, since the transfer objects are prone to cracking during laser lift-off due to full-surface irradiation, the application of the present invention, which can alleviate the propulsive force applied to the transfer objects, is effective. There are no particular restrictions on the upper limits of the longitudinal dimension and the area, but from the viewpoint of ease of production, it is recommended that they be 500 μm or less and 40,000 μm or less, respectively. ２ Of course, in the present invention, instead of the irradiation method using partial irradiation, a method of performing laser lift-off by irradiating the entire surface of the transfer object with a laser at once may also be used.

[0159] As described above in detail, the laser processing apparatus of the present invention irradiates the reduction projection optical system, so the temperature of the reduction projection optical system can be maintained at the same temperature as when the workpiece is laser processed, thereby suppressing the effects of dimensional changes in the reduction projection optical system due to temperature changes and suppressing a decrease in laser processing throughput. Furthermore, the laser processing apparatus of the present invention can suppress a decrease in laser processing throughput. Furthermore, since the shape and position of the laser irradiation can be stabilized, stable processing can always be performed regardless of the laser processing interval.

[0160] According to the transfer device of the present invention, it is possible to suppress a decrease in throughput of transfer of objects due to laser irradiation. Also, according to the laser processing method of the present invention, since the laser is irradiated onto the reduction projection optical system even when the laser optical path is blocked by the shutter, it is possible to maintain the temperature of the reduction projection optical system at the same temperature as during laser processing of the object to be processed, suppress the effect of dimensional changes of the reduction projection optical system due to temperature changes, suppress a decrease in throughput of laser processing, and it is possible to transfer the objects to be transferred reliably and in a stable position without causing defects such as breakage or cracks.

[0161] According to the laser processing method of the present invention, it is possible to suppress a decrease in throughput of laser processing. Furthermore, since the shape and position of the laser irradiation can be stabilized, stable processing can always be performed regardless of the interval between laser processing. Furthermore, according to the transfer method of the present invention, it is possible to suppress a decrease in throughput of transferring objects by laser irradiation, and the objects can be transferred reliably and in a stable position without causing defects such as breakage or cracks.

[0162] This specification includes the following aspects. [1] A laser processing apparatus including a laser device that oscillates laser light, a reduction projection optical system, and a substrate stage, and performing laser processing by irradiating a laser onto a substrate placed on the substrate stage, the laser processing apparatus having a shutter between the reduction projection optical system and the substrate stage. [2] The laser processing apparatus according to [1], wherein the shutter has an optical path changing member that forms an inclined surface with respect to the optical axis of the laser and that can be arranged on the optical axis of the laser and removed from the optical axis of the laser. [3] The laser processing apparatus according to [1] or [2], further including a damper that absorbs laser energy on the switched optical path of the laser when the shutter interrupts the optical axis of the laser and switches the optical path of the laser. [4] A laser processing apparatus including the laser processing apparatus according to any one of [1] to [3], and that irradiates the substrate with a laser to perform shape processing on the surface of the substrate. [5] A transfer device equipped with the laser processing device according to any one of [1] to [3], which transfers an object to be transferred provided on the substrate to another substrate by irradiating the object with a laser through the substrate. [6] A laser processing method using a laser processing device including a laser device that oscillates laser light, a reduction projection optical system, a substrate stage, and a shutter between the reduction projection optical system and the substrate stage to perform laser processing on a substrate placed on the substrate stage, wherein the shutter is closed while the laser light is oscillating when the substrate is not being irradiated with laser light. [7] The laser processing method according to [6], in which the shutter uses an optical path changing member that forms an inclined surface with respect to the optical axis of the laser and is arranged on the optical axis of the laser and is removable from the optical axis of the laser. [8] The laser processing method according to [6] or [7], in which the optical path of the laser is switched by closing the shutter, and the energy of the laser is absorbed by a damper arranged on the optical path of the switched laser. [9] A laser processing method using the laser processing method according to any one of [6] to [8], in which the laser processing is performed on the surface of a substrate.

[10] A transfer method using the laser processing method according to any one of [6] to [8], in which a laser is irradiated onto a transfer object provided on a substrate through the substrate, thereby transferring the transfer object to another substrate.

[0163] The present invention is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits similar effects is included within the technical scope of the present invention.

Claims

1. A laser processing device that includes a laser device that emits laser light, a reduction projection optical system, and a substrate stage, and that performs laser processing by irradiating a laser onto a substrate placed on the substrate stage, and that has a shutter between the reduction projection optical system and the substrate stage.

2. A laser processing device according to claim 1, wherein said shutter is an optical path changing member that forms an inclined surface with respect to the optical axis of said laser and that can be freely placed on said optical axis of said laser and removed from said optical axis of said laser.

3. A laser processing device according to claim 1, further comprising a damper that absorbs the energy of the laser on the switched optical path of the laser when the shutter blocks the optical axis of the laser and the optical path of the laser is switched.

4. A laser processing device comprising the laser processing device according to any one of claims 1 to 3, which irradiates a laser onto the substrate to process the shape of the surface of the substrate.

5. A transfer device equipped with a laser processing device according to any one of claims 1 to 3, which transfers an object to be transferred provided on a substrate to another substrate by irradiating the object with a laser through the substrate.

6. A laser processing method for performing laser processing by irradiating a laser onto a substrate placed on the substrate stage using a laser processing device equipped with a laser device that oscillates laser light, a reduction projection optical system, a substrate stage, and a shutter between the reduction projection optical system and the substrate stage, wherein the shutter is closed while the laser light is oscillated when the laser is not irradiating the substrate.

7. A laser processing method according to claim 6, wherein the shutter is an optical path changing member that forms an inclined surface with respect to the optical axis of the laser and that can be freely placed on the optical axis of the laser and removed from the optical axis of the laser.

8. The laser processing method according to claim 6, wherein the optical path of the laser is switched by closing the shutter, and the energy of the laser is absorbed by a damper disposed on the switched optical path of the laser.

9. A laser processing method using the laser processing method according to any one of claims 6 to 8, in which the laser processing is carried out to shape the surface of a substrate.

10. A transfer method using the laser processing method described in any one of claims 6 to 8, in which a transfer object provided on a substrate is transferred to another substrate by irradiating the object with a laser through the substrate.

Images