JP7490848B2 - Laser processing method, photomask and laser processing system - Google Patents

Description

The present invention relates to a scanning type reduction projection optical system and a laser processing device using the same.

One of the technologies used in the manufacturing process of displays and the like is to transfer microelements such as microLEDs arranged in a matrix on a donor substrate to a receptor substrate. There are also technologies for transferring various functional films, material films, organic EL films, etc., such as conductive and adhesive films, coated on a donor substrate to a receptor substrate. For example, there are various technologies such as LIFT (Laser Induced Forward Transfer) technology, stamp technology, and roll transfer technology. However, it is not easy for any of these technologies to achieve both the high-speed processing and high positional accuracy required for the process, and even at high speeds, transfer omissions and positional deviations occur.

JP 2020-4478 A JP 2006-41500 A

The applicant therefore developed a high-speed, high-precision lift device (Patent Document 1). However, the microelements on the donor substrate or receptor substrate that are transferred and mounted by the transfer device using the stamp technology or roll transfer technology used in the lift device may have defects of up to 1%. Therefore, there is a demand for technology to re-transfer microelements to these defective areas and for devices using such technology that combine both high precision and high speed.

In addition, such a technology can be used not only for retransfer from a donor substrate to a receptor substrate, but also for removing irradiated objects such as defective microelements and unnecessary material located on the substrate, and is expected to be used not only in mounting processes involving the transfer of microelements, but also in defect removal processes.

On the other hand, unlike Patent Document 1, there is a high-precision transfer technology using a step-and-repeat method. For example, in a technology for retransferring microelements to non-element locations after defective microelements on a substrate to be repaired have been removed in advance, an excimer laser beam is shaped into a laser beam with a uniform energy distribution using a beam homogenizer made up of a combination of lens arrays, and this is reduced and projected onto the microelements located on a donor substrate (for retransfer) using a photomask and a reduction projection lens, and the microelements are lifted onto the substrate to be repaired. This technology is capable of accurately lifting (retransferring) the microelements on the donor substrate onto the substrate to be repaired using a stage with high positional accuracy, but since it requires a processing time of about 1 to 2 seconds per microelement, it cannot be said to be practical in terms of production efficiency as a retransfer device used in the manufacturing process of displays, etc., where a large number of defective locations up to 1% may occur.

As a technology that allows for higher speeds, a technique is known in which a laser beam is scanned at high speed and irradiated onto the target object using an optical system that combines a galvanometer scanner and an fθ lens. Although this technique can quickly remove defective microelements from the target substrate as long as the positional accuracy of the scanner allows, there are difficulties with the subsequent re-transfer, which requires high positional accuracy, due to accuracy limitations.

To solve the problem of positional accuracy caused by the scanner, the scanned laser light is selectively directed at openings arranged on a photomask via an fθ lens or the like, and this is then reduced and projected onto a specified irradiation target located on a substrate, making it possible to construct a high-speed, high-positional accuracy scanning type reduced projection optical system that is less dependent on the scanning accuracy of the scanner. Patent Document 2 shows an example of an optical system that compensates for positional deviations in the irradiation area on a donor substrate caused by low scanning accuracy by scanning the beam of an Nd:YAG laser with a galvanometer mirror and reducing and projecting it via an fθ lens and a photomask.

However, in order to increase the size of each substrate and achieve faster processing speeds, it is necessary to enlarge the irradiation area on the donor substrate and reduce and project the scanned laser light onto many irradiation objects in a short time. In other words, it is necessary to enlarge the scannable irradiation area on the photomask. In this case, it is necessary to increase the aperture of the fθ lens and reduction projection lens used in Patent Document 2, and a telecentric design would be expensive.

Furthermore, to accommodate the miniaturization and high density of irradiation targets such as microelements, it is necessary to compensate for the accuracy limits of the scanner, as well as to provide laser light with a stable and uniform intensity distribution on the donor substrate with an extremely small irradiation area size so as not to interfere with adjacent irradiation targets. In addition, it is expected that lift devices, retransfer devices, and defect removal devices equipped with such optical systems will be realized to replace the devices described in Patent Document 1.

The objective of the present invention is to provide a scanning type reduction projection optical system that can scan a wide area with a uniform and stable energy distribution at high speed and with high precision while compensating for the lack of precision of the scanner without using a large-diameter, expensive fθ lens or telecentric reduction projection lens, and to provide a low-cost lift device for mounting or retransfer that is equipped with the same, and further to provide a method of implementing the same using the same.

The first invention is a scanning type reduced projection optical system that can be used in a laser processing device that irradiates a multi-mode pulsed laser light toward an irradiation target such as a microelement such as a mini-LED or micro-LED arranged in multiple on a substrate, or a material film or functional film attached to the substrate by coating or printing, and induces a reaction directly on the irradiation target or via a substance between the substrate and the irradiation target. The optical elements of the scanning type projection optical system are a lens array type zoom homogenizer, a scanning mirror scanned by a drive axis control device for one or more axes, a photomask, and a projection lens system that is telecentric at least on the image side, and the photomask has multiple openings of a predetermined shape that are reduced and projected, arranged at a predetermined pitch.

Furthermore, this homogenizer is a zoom homogenizer that includes a first lens array, a second lens array, and a condenser lens, and that constitutes an infinity correction optical system with the second lens array and the condenser lens, and images an illumination area of a predetermined size that covers one or more adjacent groups of openings on the photomask on the photomask, and in particular compensates for fluctuations in the position and size of the illumination area and the energy intensity distribution within the illumination area.

"Compensating for fluctuations" refers to a state in which, for example, fluctuations in the oscillation state are known to cause fluctuations in the beam pointing stability and beam size of the laser light, as well as in the intensity distribution of the beam cross section, but this zoom homogenizer avoids the effects of these fluctuations within the irradiation area imaged on the photomask. As a result, an image of a very small area with an extremely uniform energy distribution is obtained on the donor substrate projected onto the mask.

The predetermined size is a size in which the irradiation area does not reach any of the other openings adjacent to the periphery of the opening group. In other words, taking into consideration the irradiation position accuracy on the photomask due to the scanning accuracy of the scanning mirror, if the laser light passes through the adjacent opening and is irradiated to the irradiation target on the substrate (not intended to be irradiated), the boundary (outer edge) of the energy distribution above the threshold at which a reaction is induced is a size that does not reach (does not reach) any of the openings adjacent to the opening group contained in the irradiation area. As an example, in FIG. 1, the irradiation area (DP) surrounded by a dashed line illustrates the maximum allowable size of the irradiation area covering the opening group consisting of four openings (61), and the small irradiation area surrounded by a dotted line illustrates the minimum size of the irradiation area covering one opening. In the figure, each example of the irradiation area is illustrated twice to represent the deviation due to the position accuracy of the scanner.

For example, in the case where openings (squares) are arranged in a matrix on the photomask (6) as shown in FIG. 1, one side (DP) of a predetermined size of an irradiation area (square) in which n × n (n≧1) of the openings are collectively irradiated is within the range of the following formula, where Ma is the side of each opening, Pi is the pitch, and St is the scanning position accuracy on the photomask by the scanner.
Pi×(n−1)+Ma+St≦DP<Pi×(n+1)−Ma−St
If the predetermined size exceeds this range, the laser light having energy exceeding the threshold value that passes through (a part of) an unintended adjacent opening may be reduced and projected onto an unintended object to be irradiated, possibly inducing a reaction. If the shape of the opening is not square, or if n×m holes are irradiated at once, the range of the predetermined size (DP) is a design matter.

When a photomask with openings arranged in a matrix is used for batch irradiation, the pitch (Pi) of the openings on the photomask is fixed at c times the pitch of the objects to be irradiated that are to be lifted onto the receptor substrate, assuming that the reduction ratio of the reduction projection lens is 1/c.

Depending on the specifications of the reduction projection lens, the number of apertures can be chosen from a variety of designs, ranging from a single row arrangement as shown in Figure 2 to a matrix arrangement as shown in Figure 1 above. These also depend on the scanning range of the scanning mirror.

The lens elements constituting the first lens array and the second lens array are not limited to a fly-eye type, but may be cylindrical or spherical. Therefore, each lens array may be composed of a combination of orthogonal lens elements. Furthermore, there may be a zoom homogenizer in which a third lens array is added.

The second invention is a scanning type reduction projection optical system according to the first invention, in which the projection lens system includes a field lens arranged between the condenser lens and the photomask, and a reduction projection lens that is telecentric at least on the image side.

The specifications of the field lens are determined based on the specifications of the zoom homogenizer, the condenser lens (3), and the telecentric lens, and in the present invention, its preferred position is immediately before the photomask (6) as shown in FIG. 3. The focal length of this field lens (5) is designed with a curvature that allows the laser light from the zoom homogenizer (a number of focal points corresponding to the number of lens elements in the second lens array (2)) to pass through the diaphragm (7) placed at the entrance pupil position of the image-side telecentric reduction projection lens (8).

The third invention is a scanning type reduction projection optical system in which the scanning mirror (4) in the first or second invention is composed of a two-axis galvanometer scanner. This makes it possible to scan the irradiation area of the laser light toward the openings arranged in multiple rows on the photomask (6). There are various types of control devices for the scanning mirror, such as a dedicated controller or a combination of a dedicated board and a PC. Either of these can also be used to control the oscillation timing of the pulsed laser light.

The fourth invention is a scanning type reduced projection optical system using a zoom homogenizer in which an array mask consisting of an aperture group in which apertures having a size smaller than the size of each lens element constituting the lens array are arranged facing each of the lens elements, in any of the first to third inventions. The array mask is placed just before the first lens array or between the first lens array and the second lens array. This eliminates virtual images caused by stray light between the lens elements on the donor substrate onto which the aperture shape on the photomask is reduced and produces an extremely small image with a stable and highly uniform energy distribution. Furthermore, regardless of the lens element shape, a small image of any shape that matches the aperture shape or configuration of the photomask can be obtained.

When the lens elements are cylindrical, they may be used in combination with an array mask with a long and narrow aperture. The position of the array mask is a design item that is determined by checking the irradiation area on the photomask with a beam profiler or the like in the range immediately before or after the first lens array, or between the first lens array and the second lens array. The number of lens elements and the number of aperture groups on the array mask do not have to match. For example, the NA of the optical system can be adjusted by reducing the numerical aperture of the outer periphery of the array mask.

As an example of the predetermined size, if the element size of a fly-eye type first lens array or the size of the opening of the array mask arranged immediately before the first lens array is dA, the focal length of the first lens array is f1, the focal length of the second lens array is f2, and the distance between these first and second lens arrays is a (here, a = f2), the focal length of the condenser lens is fC, the focal length of the field lens that constitutes the projection lens system is fF, and the lens spacing between these lenses is b, then the predetermined size (DP) of the irradiation area imaged on the photomask is expressed by the following formula.

However, this configuration is not ideal due to the effects of aberration in the first lens array and diffraction caused by the array mask. Therefore, these problems can be avoided by moving the first lens array toward the light source and placing the array mask near the light source-side focal position of the second lens array. Furthermore, the efficiency of use of the pulsed laser light extracted by the array mask can also be improved.

The fifth invention is a scanning reduction projection optical system in which the array mask of the fourth invention has multiple types of aperture groups arranged within the surface of the substrate, allowing the aperture groups with different sizes, shapes, or numbers of apertures to be switched and used.

When the number of apertures in the array mask is less than the number of lens elements in the first lens array, the array mask has an irregular illumination function. Figure 4 shows an example of an array mask in which a group of apertures for irregular illumination and a group of opposing apertures, the same number as the lens elements in the lens array, are arranged on a single substrate.

The sixth invention is a scanning type reduction projection optical system according to the fourth or fifth invention, in which the array mask is mounted on a mount including a θ axis that allows for minute rotational adjustment around the optical axis.

A highly uniform image is obtained by overlapping the light emitted from each lens element of the second lens array on the photomask by a condenser lens. Here, in terms of the relative positional relationship between the array mask and the second lens array, misalignment in the plane perpendicular to the optical axis does not affect uniformity. However, if there is a misalignment in the rotational direction (θ) around the optical axis, the contours of the image will become blurred, resulting in multiple images. This is shown in Figure 5. (An array mask with a circular aperture shape is used here.) The effect of such misalignment in the rotational direction becomes greater as the image becomes smaller.

The seventh invention is a scanning reduction projection optical system in which the various optical elements in any one of the first to sixth inventions correspond to the oscillation wavelength of an excimer laser.

The eighth invention is a laser processing device that uses a multimode pulsed laser beam to irradiate an object to be irradiated located on a substrate to induce a reaction, and is configured to reduce and project the multimode pulsed laser beam emitted from the laser device onto a substrate held on a stage having at least X-axis and Y-axis drive axes using a scanning type reduction projection optical system described in any one of the first to sixth aspects.

The objects to be irradiated located on the substrate here include various objects such as the defective microelements mentioned above and unnecessary parts of the functional film on the circuit board. The "reactions" induced here include, but are not limited to, mechanical reactions, optical reactions, electrical reactions, magnetic reactions, and thermal reactions.

The ninth invention is a laser processing device for mounting or retransferring, or a combination of the eighth invention, in which the substrate is a donor substrate on whose surface the irradiation object is located, and the irradiation object is selectively peeled off or separated by irradiating the back surface of the donor substrate with pulsed laser light toward the irradiation object, and lifted onto a receptor substrate facing the donor substrate, and more specifically, the device is a lifting device.

The stage is a donor stage that holds the donor substrate with its back surface facing the incident side of the pulsed laser light, and further has a receptor stage that holds the receptor substrate and has an X-axis, a Y-axis, a vertical Z-axis, and a θ-axis that rotates within the X-Y plane, and the scanning reduction projection optical system and the donor stage are placed on a first base plate, and the receptor stage is placed on a second base plate or a base plate, and further the first base plate and the second base plate are each placed independently on the base plate.

Here, selectively peeling or separating the irradiated object means, when the irradiated object is a microelement, selectively peeling the microelement itself from the donor substrate, and when the irradiated object is a functional film or the like printed or coated on the donor substrate, selectively peeling or separating the functional film or the like in a portion that corresponds to the image position and size of the laser light projected in a reduced scale through the opening on the photomask. Note that this peeling or separation also includes cases where the so-called ablation process is not involved.

In addition, because both stages perform step-and-repeat operations, i.e., both stages are stationary when the laser light is irradiated, the rolling guide method, which has physical contact with the guide and is stable, is more preferable than the air bearing method, also in terms of cost.

On the other hand, the first base plate, the second base plate and the base plate on which these stages are mounted must all be made of highly rigid materials such as steel, stone or ceramic materials. The preferred stone material is granite.

With the above configuration, the positional accuracy and positional stability of the irradiation object lifted onto the receptor substrate are determined by the relative positional relationship between the mask, reduction projection lens, and donor substrate, whose fluctuations are suppressed by the scanning type reduction projection optical system and the vibration-free installation structure of the stages for each substrate, and the arrangement positional accuracy of the irradiation object on the donor substrate.

The tenth invention is a lift device according to the ninth invention, in which the control device for the scanning mirror includes a function for controlling the scanning mirror that scans the optical axis of the pulsed laser toward an opening on a photomask selected based on previously acquired position information of an object to be irradiated on the donor substrate and information on a planned lift position on the receptor substrate, and a function for controlling the irradiation of the pulsed laser light.

In particular, when the lift device is used as a retransfer device, the possibility cannot be denied that there are defective areas on the donor substrate for retransfer, such as areas without elements or areas with defective elements. Therefore, in order to irradiate only the irradiation target on the donor substrate to be lifted, which is selected based on the information on the defective areas of the receptor substrate to be lifted and the donor substrate from which the lift originates, with the laser light from the scanning type reduction projection optical system, the scanning mirror is controlled so that the optical axis scans the opening on the photomask that faces the selected irradiation target.

The eleventh invention is a lift device according to the ninth or tenth invention, in which the donor stage can hold two or more donor substrates and can be switched between them for use.

For example, a first donor substrate coated with a conductive paste film is irradiated with pulsed laser light of a predetermined size, which is reduced and projected by the scanning type reduced projection optical system according to the present invention, and a portion of the conductive paste film corresponding to that size is lifted (paste printed) to a position on the opposing receptor substrate. Next, the donor stage is moved to switch the first donor substrate to a second donor substrate (carrier substrate), and the microelement (device) on the carrier substrate is lifted to the same position on the receptor substrate and fixed via the conductive paste film.

The twelfth invention is a lift device according to any one of the ninth to eleventh inventions, in which the donor stage is suspended from the underside of the first base plate.

The order in which the axes that make up the donor stage are installed is a design matter, but preferably they are suspended from the bottom surface of the horizontally installed first base plate in the order of X-axis, Y-axis, and if the θ-axis is included, below that. The axis configuration of the receptor stage is also a design matter.

The thirteenth invention is the laser processing device according to the eighth invention, or the lift device according to any one of the ninth to twelfth inventions, characterized in that the laser device is an excimer laser device.

The 14th invention is a lifting method for mounting or retransferring an irradiation object on a donor substrate onto an opposing receptor substrate using a lifting device according to the present invention equipped with a scanning type reduction projection optical system described in any one of the 9th to 13th inventions, the lifting method including an inspection step for acquiring in advance "position information D" which is position information of the irradiation object on the donor substrate and "position information R" which is a planned lift position of the irradiation object onto the receptor substrate, a division step for dividing an area on the donor substrate into "division areas D" of a predetermined size, and a selection step for selecting the position of the irradiation object within the division area D to be lifted based on the position information D and the position information R. This lifting method includes a transfer process in which the selected irradiation object in the divided area D is lifted toward the "divided area R," which is defined as the area on the receptor substrate facing the divided area D for convenience, by laser light that passes through an opening on a photomask that faces the position of the selected irradiation object (via a reduction projection lens) and is irradiated onto the donor substrate, and a movement process in which the donor substrate and the receptor substrate are moved to the next lift area after the transfer process. Thereafter, the transfer process and the movement process are repeated, and the selected irradiation object on the donor substrate is mounted or re-transferred onto the receptor substrate for the entire area of the receptor substrate that is to be lifted.

In the inspection process, there are various methods for obtaining position information of the mounted irradiation target, but it is a design matter, such as using the individual center of gravity coordinates obtained by processing images of all or two or more individual irradiation targets by sampling. Determining the origin position of these coordinates is also a design matter. Position information D and/or position information R may be inspected using an inspection device independent of this lift device, and the results may be obtained via a communication means by the control device of this lift device, or may be calculated from design values based on the measurement results when positioning (aligning) the donor substrate and receptor substrate by this lift device. Note that this inspection process is desirably performed before the division process, although it depends on the total takt time for mounting or retransfer.

The position of the selected irradiation object in the divided area D refers to the position of all irradiation objects (excluding defective areas) on the donor substrate that face the intended lift position in the opposing divided area R when this lift method is used for implementation, and refers to the position of the irradiation object (excluding defective areas (non-element areas)) on the donor substrate that faces the defective areas (non-element areas) on the receptor substrate when used for retransfer.

The transfer process includes both cases where the scanning mirror does not stop scanning, and where the pulsed laser light is oscillated in synchronization with the time when the optical axis is scanned over the position of the selected irradiation object, and cases where scanning and stopping are repeated.

Furthermore, the position information D can include not only the position coordinates of the microelement as the irradiation object normally mounted on the donor substrate or the irradiation object that can be normally peeled or separated, but also the position coordinates of the irradiation object that is identified as defective or missing (as abnormal position information). The same applies to the position information R when this lift method is used for re-transfer.

The maximum size of the division area D depends on the reduction projection lens that constitutes the scanning reduction projection optical system mounted on this lift device. In particular, the numerical aperture and magnification of a telecentric reduction projection lens are limited in consideration of its manufacturing cost, and depending on these specifications, the area on the photomask, and therefore on the donor substrate, that can be lifted in one scan is limited.

In this lifting method, regardless of whether the lifting device is used for mounting or retransfer, the above-mentioned divided area D is set in the area of the donor substrate, and the donor substrate and receptor substrate are moved by the step-and-repeat motion of each stage that holds them, and vibration is avoided when the stages stop, allowing for precise lifting.

The fifteenth invention is a lift method according to the fourteenth invention, in which the design mounting pitch of the irradiation target on the donor substrate is 1/an integer greater than or equal to 1, such as 1/2, 1/3, etc., of the design mounting pitch calculated from the position information R when the lift method is used for mounting, or of the design mounting pitch of the irradiation target on the receptor substrate that has already been mounted when the lift method is used for retransfer.

Note that when the planned lift positions on the receptor substrate are arranged in an X x Y matrix, this also includes cases where the mounting pitch on the opposing donor substrate of the same size is 1/n times in the X column and 1/m times in the Y column (n and m are different integers greater than or equal to 1).

In the sixteenth invention, first, it is assumed that there is an error between the actual mounting pitch of the irradiated object on the donor substrate, calculated from the position information D acquired in the inspection process, and the mounting pitch on the receptor substrate, calculated from the position information R (taking into account the difference in the mounting density on the donor substrate). When this lift method is used for mounting, this mounting pitch on the receptor substrate is calculated from the planned lift position (design position) of the irradiated object, and when used for retransfer, it is the actual mounting pitch of the irradiated object that has already been mounted.

In light of the manufacturing process of the donor substrate, even if there are no defective elements or no-element areas on the donor substrate, the actual mounting pitch of the mounted irradiation objects may have an error (δPi) from the designed mounting pitch. And even if this error does not tend to vary depending on the location on the same substrate, it is possible that there may be differences (errors) between donor substrate manufacturing lots and even between donor substrates. In this case, the error δPi accumulates according to the number of irradiation objects contained within the divided area D.

The sixteenth aspect of the present invention is a lift method in which the movement amount of each substrate in the movement process of the fifteenth aspect is set to a movement amount that offsets this "accumulated error amount."

In the sixteenth invention, when attempting to lift the irradiation objects in the divided area D using a donor substrate with an error (δPi) of a certain magnitude or more, depending on the positions of the irradiation objects in that area (the number of irradiation objects from the reference position), the accumulated error amount there may exceed the allowable range in terms of lift position accuracy. In addition to the deviation between the intended lift position on the receptor substrate and the position of the irradiation object on the lifted donor substrate, the deviation between the intended position where the laser light passing through the opening on the photomask is imaged on the donor substrate and the position of the irradiation object to be irradiated by the laser light becomes a particular problem when the mounting density of the irradiation objects on the donor substrate is high and the pitch is narrow.

Therefore, in the 17th invention, the distance between adjacent irradiation objects on the donor substrate is set as the upper limit, and the range of the allowable cumulative error amount is determined taking into consideration the difference between the irradiation size of the laser light irradiated toward the irradiation object on the donor substrate and the size of the irradiation object, and the effect of the positional deviation on the lift position accuracy. If the cumulative error amount in the divided area D exceeds this allowable range at the position where the cumulative error amount is maximum (for example, the lower right end when the upper left end is used as the reference), the size of the divided area D in the division process of the 16th invention is further reduced to a size where the cumulative error amount at that position falls within the allowable range, resulting in a "corrected divided area D."

Then, the selected irradiation object in the correction division area D is mounted or retransferred into a "correction division area R" on the opposing receptor substrate, which is also set to the same size for convenience. After that, a movement process is performed in which the donor substrate and receptor substrate are moved by the stage in order to lift them to the next correction division area R. At that time, the movement amount of each stage is adjusted so as to cancel out the accumulated error amount.

When determining the allowable range of the accumulated error amount, even if the accumulated error amount does not exceed the aforementioned maximum value within one divided area D, it is advisable to determine this allowable range (size of the modified divided area D) on the assumption that the maximum value may be exceeded as a result of repeating the movement process according to the design pitch on the donor substrate (or on the receptor substrate) for the entire receptor substrate, or by simulating this in advance.

The 18th invention is a lifting method according to the 17th invention, in which the size of the corrected divided area D, the combination of the movement amounts of each stage, and the order of each process are determined by a simulation program using position information D, position information R, the size of the divided area D, and the tolerance range as parameters, so as to minimize the time required for mounting or retransferring the entire receptor substrate.

The present invention provides a scanning type reduction optical system that quickly scans a small and stable irradiation area with a uniform and stable energy distribution toward an aperture arranged on a photomask while compensating for the lack of scanning accuracy of a scanning mirror without using a large-diameter fθ lens or telecentric projection lens, and projects a highly uniform and highly accurate reduced image onto an object to be irradiated, as well as a defect removal device and a lift device for mounting or retransfer that are equipped with the same, all at low cost.

FIG. 1 is a conceptual diagram illustrating a photomask in which openings are arranged in a matrix. FIG. 1 is a conceptual diagram illustrating a photomask in which openings are arranged in a row. A conceptual diagram illustrating the arrangement of components of a scanning reduction projection optical system (without an array mask). FIG. 1 is a schematic diagram illustrating an array mask in which a plurality of aperture groups are arranged. Beam profiler image of the irradiated area on the photomask (θ axis offset). 1 is a schematic conceptual diagram (three-dimensional) of a lift device equipped with a scanning type reduction projection optical system. FIG. 1 is a schematic conceptual diagram of a lift device equipped with a scanning type reduction projection optical system. A conceptual diagram of the element configuration of a zoom homogenizer. A conceptual diagram of an array mask. Photo of the array mask. FIG. 1 is a conceptual diagram showing the arrangement of each optical element from the zoom homogenizer to the donor substrate. Beam profile image showing the imaging state on the photomask when a rectangular array mask is inserted. Beam profile image showing the imaging state on the photomask when a circular array mask is inserted. FIG. 2 is a conceptual diagram of a photomask used in Example 1. A reduced-scale image of the laser beam profile projected onto the donor substrate. A conceptual diagram of an area in which microelements are mounted over the entire effective area of a donor substrate. A conceptual diagram of a 6-inch donor substrate divided into 27 separate areas. 1 is a conceptual diagram showing the relationship between the position on a donor substrate and the amount of accumulated error. 11 is a conceptual diagram showing an overlapping state of defect position information D and defect position information R. 1 is a conceptual diagram showing how the divided areas of opposing substrates are lifted up while facing each other. 1 is a conceptual diagram showing how each of the divided areas of the substrate, which do not face each other, is lifted in an opposing manner.

Below, the embodiment of the present invention will be described using specific examples and figures. Note that in the following description, the above-mentioned conceptual diagrams may be used for convenience.

In this embodiment 1, an example of a lift device is shown in which irradiation objects, which are microelements (micro LED elements) of size 30 x 60 [μm] (X axis x Y axis) arranged in a matrix on a 6-inch donor substrate, are mounted in a matrix of 222 x 225 elements, totaling 49,950 elements, on a receptor substrate of the same size. The lift position accuracy required for these approximately 50,000 microelements mounted on the receptor substrate is ±2 [μm], and the pitch in each axial direction is 450 [μm]. Note that on the donor substrate, the microelements are arranged without defects (without any non-element areas) at a pitch 1/2 times the mounting pitch of the intended lift position on the receptor substrate, and the total number of microelements is approximately 200,000. The distance (spacing) between adjacent microelements is X: 195 [μm], Y: 165 [μm]. For simplicity in this example, the size of the receptor substrate is the same as that of the donor substrate, and the array pitch of the microelements is the same on both the X and Y axes, but these are all design considerations.

First, an example of the appearance of a lift device according to the present invention is shown in FIG. 6A. The configuration of this appearance diagram is compatible with receptor substrates of 55 inches or more in size. A conceptual diagram of the layout of the main components is shown in FIG. 6B. Note that in FIG. 6B, the laser device, various control devices, and mounts for other optical elements are omitted, and the X-axis, Y-axis, and Z-axis directions are shown in the diagram. The first base plate (G11, G12) and the second base plate (G2) are all stone base plates made of granite. And the base base plate (G) is made of highly rigid iron.

It is also desirable to have a rotation adjustment mechanism between each base plate and between each base plate and each stage to finely adjust the installation angle (perpendicular/parallel). Specifically, the rotation adjustment mechanism described in the above-mentioned Patent Document 1 is preferable. Furthermore, it is desirable to have a high-magnification camera that monitors the position of each substrate installed in a location separate from the vibration system of the stage that holds the substrate.

The laser device used in this embodiment 1 is an excimer laser with an oscillation wavelength of 248 nm. The spatial distribution of the emitted laser light is approximately 8 x 24 mm, and the beam spread angle is 1 x 3 mrad. All are expressed in terms of (length x width), and the numerical values are FWHM. There are various specifications for excimer lasers, including differences in output, repetition frequency, beam size, and beam spread angle, as well as laser light emitted vertically (with the vertical and horizontal directions reversed). However, there are many excimer lasers that can be used in this embodiment by adding, omitting, or modifying the design of the optical system. In addition, depending on the size of the laser device, it may be installed on a base different from the base on which the stages of the lift device are generally installed.

The light emitted from the excimer laser enters the telescope optical system and propagates to the zoom homogenizer beyond. Here, the zoom homogenizer is placed on the first base plate (G11) so that its optical axis is aligned with the X-axis, as shown in FIG. 6B. The laser light just before entering the zoom homogenizer is adjusted by the telescope optical system so that it becomes a roughly parallel light, and enters the zoom homogenizer along the X-axis with roughly the same size regardless of the position of the zoom homogenizer. In this embodiment, the size is roughly 25 x 25 mm (Z x Y).

Each lens array (1, 2) constituting the zoom homogenizer in this embodiment is a pair of uniaxial cylindrical lens arrays combined at right angles in the YZ plane perpendicular to the optical axis, as shown in the conceptual diagram in Fig. 7. Laser light enters the first lens array (1) of the first set, and while being condensed, passes through an array mask (10) placed near the light source side focal position of the second lens array (2) in the latter set, and propagates in this order through the second lens array (2) and the condenser lens (3).
In this embodiment, an array mask having 0.75 mm square openings arranged in a matrix was used. A conceptual diagram of this is shown in FIG. 8A. In this conceptual diagram, the positional relationship between the array mask (10) and its openings (101) arranged just before the fly-eye type lens array (1) is shown in a conceptual diagram to show the relative state with respect to the lens array. The state of the array mask used in this embodiment is shown in FIG. 8B.

Figure 9 shows a conceptual diagram of the arrangement of each optical element from the zoom homogenizer to the donor substrate. The detailed arrangement is a matter of design. The laser light emitted from the zoom homogenizer is scanned by a two-axis scanning mirror (4) and its control device, propagates to the field lens (5), and is imaged on the photomask (6).

The image plane on the photomask (6) is the image plane of an infinity correction optical system composed of the second lens array (2) and condenser lens (3), with the aperture (101) of the array mask (10) as the object plane.
The laser light is scanned by the scanning mirror (4) and propagates toward one selected opening (61) on the photomask (6), forming an image in an irradiation area of a predetermined size. FIG. 10A is a beam profile image. This predetermined size is the boundary (outer periphery/edge) of the energy distribution that has a threshold value or more that induces a reaction when an unintended irradiation target is irradiated through an opening on an unselected adjacent photomask, and in this embodiment, it is approximately 1 [mm] (FWHM). FIG. 10B is a beam profile on the same photomask (6) when an array mask (10) with a circular opening shape is used.

The photomask (6) in this embodiment 1 is a synthetic quartz plate on which a pattern is drawn (applied) by chrome plating. A conceptual diagram is shown in FIG. 11. The laser light passes through the window portion (61) shown in white, which is not chrome plated, and is blocked by the colored portion (62) which is chrome plated. The size of the opening is 60 x 100 [μm], and 74 openings are arranged at a pitch of 600 [μm] in the X-axis direction, and 25 openings are arranged at the same pitch in the Y-axis direction, for a total of 1850 openings. The surface to be chrome plated is the laser light emission side, while the incident side is coated with an anti-reflection film for 248 [nm]. Furthermore, aluminum deposition or a dielectric multilayer film can be used instead of chrome plating.

The photomask (6) and array mask (10) are each fixed to a dedicated mount (not shown), and this mount has a six-axis adjustment mechanism including the W axis, U axis, and V axis that move in the X-axis, Y-axis, and Z-axis directions, respectively, the R axis (θ axis) which is a rotation axis (around the optical axis) in the YZ plane, the TV axis that adjusts the tilt relative to the V axis, and the TU axis that adjusts the tilt relative to the U axis.

The optical axis of the laser light passing through the zoom homogenizer is scanned at high speed over the openings on the photomask by the scanning mirror (4), and the excimer laser device oscillates in pulses in synchronization with the timing at which the optical axis is scanned over the position of each opening.

The laser light that passes through the photomask pattern propagates through an aperture (7) to an image-side telecentric projection lens (8) with a reduction ratio of 3/4, and is then reduced and projected onto the donor substrate (91) from its rear surface to the position on the front surface (bottom surface) where a microelement with a size of 30 x 60 [μm] (X x Y) is mounted. Figure 12 is a beam profile image of the projected laser light. The microelements on the donor substrate irradiated with the scanned laser light are lifted in a matrix pattern on the opposing receptor substrate one after another at a pitch of 450 [μm] and mounted.

The number of lifted 30 x 60 μm irradiation objects corresponds to the number of the aforementioned 74 x 25 openings on the photomask, and the lift range is approximately 33 x 11 mm.

The reduction projection lens (8) is image-side telecentric, and in addition to adjustment using a Z-axis driven stage that holds it, it is also possible to add an adjustment function for the donor substrate in the Z-axis direction (Z-axis stage (Zd)) to support imaging on the light absorption layer. However, it is necessary to take into consideration the decrease in lift position accuracy due to the increased load on the donor stage.

When adjusting the imaging position at the interface between the donor substrate surface and the light absorbing layer, etc., a real-time monitor using a confocal beam profiler (BP) whose imaging plane is a plane that is conjugate to the mask surface and the reduction projection lens is effective. In this embodiment 1, the spatial intensity distribution of the laser light that is reduced and projected onto the interface between the donor substrate surface and the microelement is monitored in real time and with high resolution.

The laser light is scanned toward all the apertures on the photomask (6), and the laser light is sequentially irradiated toward the microelements arranged on the donor substrate whose imaging position has been adjusted. As a result, 1850 microelements, which correspond to the number of apertures on the photomask, are mounted on the receptor substrate at the same number of planned lift positions. The 1850 lift areas correspond to one area when the receptor substrate is divided into three (A-C) in the X-axis direction and nine (1-9) in the Y-axis direction, for a total of 27 divisions (A1-A9, B1-B9, C1-C9). The size is approximately 33 x 11 [mm], determined by the scanning angle of the scanning mirror and the aperture diameter of the reduction projection lens. After the lift for this one area is completed, the donor substrate and the receptor substrate are moved to the next lift area. For example, the movement is 33.3 [mm] in the X-axis direction and 11.25 [mm] in the Y-axis direction. After that, lifting is performed again at 1,850 locations, and this process is repeated for all the planned lift positions, completing the implementation of 49,950 microelements from the donor substrate to the receptor substrate. As mentioned above, the donor substrate has microelements mounted without defects at a high density of 1/2 the pitch of the planned lift positions on the receptor substrate, so one donor substrate can be used to implement mounting on four receptor substrates.

In addition, depending on the relationship between the image size of each opening of the laser light on the donor substrate and its energy density, if the predetermined size (DP) of the irradiation area of the laser light on the photomask can be set to a size that allows four openings to be irradiated at once, for example, as shown by the dashed dotted line in Figure 1, the time required for mounting can be reduced to approximately 1/4.

Also, as shown in Figure 13, when using a donor substrate in the shape of a wafer with microelements mounted over its entire effective area, it is possible to lift microelements located in every corner by setting a lift area (the area indicated by diagonal lines in the figure) along the mounting area of the microelements and scanning the scanning range of the scanning mirror in accordance with this.

The above is a specific example of a lift device and mounting method for mounting microelements on a donor substrate onto an opposing receptor substrate.

In this embodiment 2, assuming that there is no transfer failure, 495 x 495 = 245,025 40 [μm] square microelements are mounted in a matrix with adjacent elements at a pitch of 200 [μm] on a 6-inch receptor substrate (hereinafter, simply referred to as the "receptor substrate" in this embodiment 2), and a correction example is shown using a correction lift device according to the present invention to correct defective areas equivalent to about 1% of the substrate. In addition, like the receptor substrate, the microelements used for retransfer (correction) arranged on the 6-inch correction donor substrate (hereinafter, simply referred to as the "donor substrate" in this embodiment) also have about 1% of non-element areas (and defective areas) distributed. Note that on the donor substrate in this embodiment 2, microelements are arranged at a pitch of 50 [μm], which is 1/4 times the design mounting pitch of the microelements mounted on the receptor substrate, and the total number of microelements is more than 3.9 million. Therefore, the distance between adjacent microelements is 10 [μm]. In addition, the schematic configuration of the scanning reduction projection optical system mounted on the lift device of this embodiment 2 and the structure of the device are the same as those of the first embodiment, but the specifications of each optical element, their arrangement positions, and the beam profile shape determined by these are design matters.

In the photomask (6) in this embodiment, as shown in FIG. 1, 200 [μm] square openings (Ma), which are slightly larger than the shape determined by the magnification (1/4 times) of the reduction projection lens (8) and the microelement size (40 [μm] square), are arranged in a matrix of 165 x 55 with a pitch (Pi) of 800 [μm]. This arrangement corresponds to the arrangement of the microelements mounted on the receptor substrate. The size of the irradiation area imaged on this photomask by the scanning type reduction projection optical system is about 1 [mm] square, the same as in the embodiment 1, and is a size that can be irradiated without interfering with adjacent openings on the photomask. The laser light that passes through this opening is imaged toward the microelement used for retransfer (correction) on the donor substrate (9) via the image-side telecentric reduction projection lens (8).

The excimer laser light having the irradiation area size, which is pulsed in synchronization with the operation of the scanning mirror (4), is irradiated onto an opening of 200 μm square on the photomask (6). The laser light passing through this opening passes through an image-side telecentric projection lens (8) with a reduction ratio of 1/4, and is irradiated from the back surface of the donor substrate toward the microelements arranged on it at intervals of 10 μm without interfering with adjacent microelements. In this embodiment, the irradiated pulsed laser light forms an image on the front surface (lower surface) of the donor substrate at a 50 μm square, which is slightly larger than the size of the microelements, and induces a reaction, lifting the microelements at that position toward the non-element areas on the receptor substrate.

A specific lifting method for retransfer (correction) will be described below for each step.
(1) Inspection process: The position information of the microelements mounted on the donor substrate and the receptor substrate is obtained by acquiring the design position information and the actual mounting position obtained by image processing. The specific coordinates are the center of gravity position obtained from the shape of the microelement, and the coordinate origin is determined by referring to the position of the orientation flat of the substrate. Here, the position information on the donor substrate is called "position information D" and the position information on the receptor substrate is called "position information R".

Position information D includes microelements that are recognized as defective and should not be used for retransfer, and non-element locations that are not mounted in the first place. The position coordinates of these are calculated from adjacent microelements and obtained as "defective position information D." The same applies to "defective position information R" in position information R.

In addition, in this embodiment, the design pitch of the microelements arranged on the donor substrate is 1/4 the design pitch of the microelements mounted on the receptor substrate, and the actual pitch has an error between the donor substrates and between the receptor substrate. Therefore, this error is calculated from the position information D and R. For simplicity, in this embodiment, the position information R is set to the design pitch, and the value of the error δPi of the pitch of the donor substrate relative to that pitch is +0.0075 [μm].

(2) Dividing Step The area on the 6-inch donor substrate is divided into 27 divided areas ("divided areas D") in the same manner as in Example 1. As shown in FIG. 14, each area is 33×11 mm, and for convenience, each divided area is shown in the figure as A1 to A9, B1 to B9, and C1 to C9. The receptor substrate is also divided into 27 "divided areas R", and lifting is performed between the opposing divided areas.

The size of this division area D is a design item determined by the effective aperture diameter of the reduction projection lens, the size of the photomask limited by other specifications, and the reduction projection magnification, as in the first embodiment.

Here, the allowable range of the cumulative error amount obtained by multiplying the number of irradiation objects contained in the divided area D in the long axis (X-axis) direction, 660(-1), by the above-mentioned error δPi was set to ±5 μm.
As shown in FIG. 15, when the upper left end of the division area D (dash line) is used as the reference for alignment, the allowable range is arbitrarily set based on the limit at which the 50 [μm] square (dashed line in the figure), which is the size at which the laser light passing through the opening (61) on the photomask (6) forms an image on a 40 [μm] square microelement on the donor substrate, can irradiate the entire surface of the microelement (solid line) located at the right end position where the accumulated error amount is maximum. Note that the 40 [μm] square of the two-dot chain line in the figure is the mounting position of the microelement on the donor substrate in the design, and is located in the center with respect to the image size of the dashed line. In this embodiment, the accumulated error amount of any microelement mounted in the division area D is within the allowable range (659×0.0075≒4.94) with respect to the design position there, so there is no need to set a reduced "corrected division area D" in this division process.

(3) Selection process: For a divided area R of the same size facing the divided area D, a micro-element arranged in the divided area D is selectively lifted one-to-one toward a non-element location (approximately 91 defective location information R) which accounts for approximately 1% of the 9,075 micro-elements implemented in the divided area R, and the micro-element located opposite the non-element location is lifted one-to-one.

However, of the microelements (660 x 220 = 145,200 elements) mounted within divided area D, there are 1,452 defective elements, which is approximately 1%, and these (defective position information D) may overlap with defective position information R. This is shown in Figure 16. Here, the image is of the receptor substrate being observed through the donor substrate. A partial area of the array of microelements arranged on the donor substrate is shown. In this figure, the upper left area of divided area A1 surrounded by a dashed line is enlarged, and the arrangement of the microelements on the donor substrate located within this area is illustrated.

Here, for convenience, the positions of the non-element areas where defective elements have been removed from the receptor substrate in a removal process are shown with open squares (Mr), the positions of the microelements that are similarly mounted normally on the receptor substrate are shown with black squares (Er), and the positions of the microelements on the donor substrate, which are densely arranged at 16 times the density of the receptor substrate, are shown with grey squares (Ed). (Ed overlapping with Er and Mr is not shown.) As mentioned above, the pitch of the microelements Ed on the donor substrate is 50 [μm], and the pitch of the microelements Er on the receptor substrate is 200 [μm].

First, a case will be described in which the first receptor substrate is repaired using a donor substrate used for repair for the first time.
(3-1) The defective position information D and the defective position information R are compared on a board-by-board basis to confirm in advance the positions where the non-element location (Mr) and the defective element location (Md) overlap. The presence or absence of overlap to be confirmed here means the overlap of the board unit (all 27 areas) at the positions where the β array group aligned in the X-axis direction of the donor board shown in the figure intersects with the α array group aligned in the Y-axis direction (total of 245,025 positions/board). Note that the other α', α'', α''', β', β'', and β''' array groups represent the arrangement positions of other microelements on the donor board that are mounted at 16 times the density. (In the figure, the α array group is shown with arrows for only the three rows from the left, and the β array group is shown with arrows for only the two rows from the top. The other "'" array groups are also shown with limited arrows in the same way.)

If there is no overlap, the selection step selects the position (Ed) of the microelement on the donor substrate that corresponds to the non-element portion (Mr). If an overlap is confirmed, the procedure will be described later.

(3-2) On the other hand, in the case of repairs that involve a combination of a donor substrate that has already been used for repairs and a (first or) second or subsequent receptor substrate, all of the position information (1% Md + used Md), which is the original position information (Md) of the approximately 1% of defective elements on the donor substrate plus the position information of used substrates that are missing microelements due to past use in retransfer, is compared with the distribution position information (Mr) of the element-free locations on the receptor substrate to check in advance whether there is any overlap. If there is no overlap, then in the selection process, the position (Ed) of the microelement on the donor substrate that corresponds to the element-free location (Mr) is selected.

(4) Transfer process In the above-mentioned cases (3-1) or (3-2), after the position of the microelement on the donor substrate to be used for retransfer is selected, retransfer of the first or second or subsequent receptor substrate is started from the above-mentioned divided area A1. The optical axis of the laser light is scanned along the β row on the donor substrate by the scanning mirror (4) via the photomask (6) and the reduction projection lens (8). Within this area, the microelement mounted at the selected position on the donor substrate is lifted toward the opposing non-element area (Mr) on the receptor substrate by the excimer laser light oscillated at the timing when the optical axis is scanned to the selected position.

(5) Movement process After the area A1 of the receptor substrate has been modified using the microelement at a selected position within the area A1 of the donor substrate, the next area A2 is modified in the same manner. The areas are moved by moving the stage holding each substrate, and all areas are modified in any order (e.g., A1-A9→B1-B9→C1-C9). The amount of stage movement during the movement of each divided area is set so as to offset the aforementioned accumulated error amount (approximately +4.95 μm). After the modification of all divided areas that require modification has been completed, the receptor substrate is replaced with the next receptor substrate to be modified.

On the other hand, if overlap is confirmed in the comparison by substrate unit in the above (3-1) or (3-2), the column group to be compared is changed from α to α' column group or from β to β' column group, and the combination of column groups after the change (intersection of the changed column groups) is compared by substrate unit to check for overlap as in the above (3-1) or (3-2). In this case, there are 15 possible combinations of column groups. If a combination of column groups without overlap is found by substrate unit, the position (Ed) of the microelement on the donor substrate corresponding to the non-element portion (Mr) is selected based on that combination. Note that the substrate is moved according to the combination of column groups before the transfer process. Figure 17 shows the position between the substrates at the time of re-transfer between each divided area (A1).

In addition, in the comparison of substrate units in (3-1) or (3-2) described above, if no combination of column groups without overlaps is found in any of the 15 combinations, comparison is performed not in broad substrate units but in narrow opposing divided areas. For example, comparison is limited to area A1 of the receptor substrate and area A1 of the donor substrate facing it. As a result, if there is no overlap at the intersection of the α column group and the β column group, the process proceeds directly to the transfer process, and if there is overlap, a search is made for other combinations of column groups without overlaps (e.g., α' column group and β'' column group) at least within the divided area (A1) of each opposing substrate. There are a maximum of 16 such combinations. After the correction of the divided area A1 of the receptor substrate by the divided area A1 of the donor substrate is completed in the combination of column groups without overlaps that has been found, the next area A2 is subjected to a similar comparison, and the area A2 of the receptor substrate is corrected in the combination of column groups without overlaps. After that, this process is repeated for donor A3 and receptor A3, donor A4 and receptor A4, etc. Note that if there is overlap only between divided areas B5, and there is no overlap on a board-by-board basis except for this area, there is no need to compare areas limited to those before and after.

If no combination of column groups without overlaps is found in the aforementioned comparison of opposing divided areas (A1 and A1, B1 and B1, etc.), the area on the donor substrate to be compared is removed from the comparison limited to the opposing divided areas to the comparison of the other 26 divided areas of the donor substrate, and a combination of column groups without overlaps is searched for area by area. Figure 18 shows how this is done. Here, in the combination of divided area C5 of the donor substrate and divided area A3 of the receptor substrate, for example, retransfer is performed at the intersection position of the α'''' group and the β'''' group. However, it should be noted that a combination of column groups without overlaps must be searched for between the divided areas, taking into account the defective position information (Md) that reflects the defective position of the microelement that has been used for repair by the time the divided area to be compared is changed. In addition, it is necessary to consider (calculate) whether a reasonable takt time can be realized by comprehensively taking into account the time required for frequent movement of the column groups and for moving the stage to the opposing divided area. Based on the calculation results, the appropriate range of overlaps is selected and the timing of donor substrate replacement is determined.

As long as direct irradiation of the laser light onto the receptor substrate does not have an adverse effect, the transfer process can be carried out regardless of whether there is overlap in the defective position information, and for example, non-element locations that were not retransferred due to overlap can be left to a second or subsequent correction using a different donor substrate. Furthermore, matching for each substrate and matching for each divided area can be combined in a timely manner based on a simulation of the takt time, and it is also possible to determine the combination of each matching method and its range that results in the shortest simulated takt time based on the position information of each substrate previously obtained in the inspection process.

When retransferring for each divided area R as in this embodiment, that is, when retransferring by scanning a scanning mirror with a scan speed of about 30/sec for each aperture number on the photomask (165 x 55) in one go, if there is no overlap of defective positions between substrates, the time required for repairing one divided area (about 90 locations) is about 3 seconds. Even when taking into account the time to do this for 27 divided areas and the time it takes to move each substrate to move between the divided areas, the time required from when the substrate is set to when repairing is completed is roughly around 90 seconds.

Compared to the takt time of about 2,450 seconds when using the aforementioned conventional device, which requires about one second to retransfer a single microelement, this allows for the correction of up to 1% of defective elements at an overwhelming speed. Even when taking into account the calculation time required for matching (checking for overlaps) and the stage movement time required for the above-mentioned column group movement and division area movement to avoid overlaps, the overwhelming superiority of the takt time in this embodiment can be maintained.

When comparing divided areas randomly, not just with opposing divided areas, or when taking the cumulative error amount into consideration, it is advisable to determine the size of the corrected divided area D, the combination of the movement amounts of each stage, and the order of execution of each process so as to minimize the time required for mounting or retransferring the entire receptor substrate, and optimize each process, using a simulation program with parameters set to the position information D and position information R obtained in the inspection process, the size of the divided area D, and the allowable range of the cumulative error amount.

Although the embodiment of the present invention has been described in detail above, the present invention can be expressed from different viewpoints as follows (1) to (19).
(1) A scanning type reduction projection optical system used in a laser processing device that irradiates a laser beam toward an object to be irradiated to induce a reaction, the scanning type reduction projection optical system having an infinity correction optical system, a scanning mirror, and a photomask.
(2) A laser processing apparatus that irradiates a laser beam toward an object to be irradiated to induce a reaction, the laser processing apparatus having a laser device that oscillates the laser beam, an infinity correction optical system, and a scanning mirror.
(3) A lift device for irradiating a laser beam toward a donor substrate on which an irradiation object is provided and moving the irradiation object from the donor substrate to a receptor substrate, the lift device having a laser device that oscillates the laser beam, an infinity correction optical system, and a scanning mirror.
(4) A laser processing method for irradiating an object with laser light to induce a reaction, the method comprising the steps of: irradiating the object with laser light using a scanning reduction projection optical system having an infinity correction optical system, a scanning mirror, and a photomask.
(5) A lifting method for irradiating a laser beam toward a donor substrate on which an irradiation object is provided, and moving the irradiation object from the donor substrate to a receptor substrate, the lifting method being characterized in that the laser beam is irradiated toward the irradiation object using a scanning reduction projection optical system having an infinity correction optical system, a scanning mirror, and a photomask.
(6) A method for manufacturing a substrate having an irradiation object mounted thereon, comprising irradiating a laser beam toward a donor substrate having an irradiation object provided thereon, and moving the irradiation object from the donor substrate to a receptor substrate, the method comprising irradiating the laser beam toward the irradiation object using a scanning reduction projection optical system having an infinity correction optical system, a scanning mirror, and a photomask.
(7) The method for manufacturing a substrate mounted with an irradiation object according to (6), wherein the irradiation object is a microelement.
(8) The method for manufacturing a substrate on which an object to be irradiated is mounted according to (7), wherein the microelement is a micro LED.
(9) The method for manufacturing a substrate mounted with an irradiation object according to (7) or (8), wherein the microelements are arranged in a matrix on the donor substrate.
(10) The method for manufacturing a substrate mounted with an irradiation object according to (6), wherein the irradiation object is a film.
(11) The method for manufacturing a substrate on which an object to be irradiated is mounted according to (10), wherein the film is a conductive film or an adhesive film.
(12) The method for manufacturing a substrate on which an object to be irradiated is mounted according to (10), wherein the film is an organic EL film.
(13) A method for manufacturing a substrate having a microelement mounted thereon, comprising the steps of irradiating a laser beam toward a first donor substrate having a film thereon, and transferring the film from the first donor substrate to a receptor substrate to obtain a substrate having a film mounted thereon, and irradiating a laser beam toward a second donor substrate having a microelement thereon, and transferring the microelement from the second donor substrate onto the film of the substrate having the film mounted thereon, characterized in that laser beam is irradiated toward the film or the microelement using a scanning reduction projection optical system having an infinity correction optical system, a scanning mirror, and a photomask.
(14) A method for removing a defective portion of a donor substrate having a defective portion, comprising irradiating the defective portion with a laser beam to remove the defective portion from the donor substrate, the method comprising the steps of irradiating the laser beam to the defective portion using a scanning reduction projection optical system having an infinity correction optical system, a scanning mirror, and a photomask.
(15) A retransfer method for irradiating a laser beam toward a donor substrate on which an irradiation object is provided, and moving the irradiation object from the donor substrate to a receptor substrate, the receptor substrate having an area where the irradiation object is already mounted and a defective area where the irradiation object is not mounted in the planned mounting area, the retransfer method comprising: irradiating a laser beam toward the irradiation object provided on the donor substrate using a scanning reduction projection optical system having an infinity correction optical system, a scanning mirror, and a photomask, and moving the irradiation object to the defective area of the receptor substrate.
(16) A lifting method for irradiating a laser beam toward a donor substrate on which an irradiation object is provided, and moving the irradiation object from the donor substrate to a receptor substrate, the lifting method being characterized in that the irradiation object provided on the donor substrate has a defective area, and a laser beam is irradiated toward the irradiation object other than the defective area using a scanning reduction projection optical system having an infinity correction optical system, a scanning mirror, and a photomask, and the irradiation object is moved to the receptor substrate.
(17) A laser processing method in which a laser beam is irradiated toward an object to be irradiated to induce a reaction, the laser beam being scanned by a scanning mirror and focused on a photomask as an image plane of an infinity corrected optical system, and the laser beam passing through the photomask being projected in a reduced form onto the object to be irradiated.
(18) A lifting method for irradiating a laser beam toward a donor substrate on which an irradiation object is provided, and moving the irradiation object from the donor substrate to a receptor substrate, characterized in that the laser beam is scanned by a scanning mirror and focused on a photomask as an image plane of an infinity correction optical system, and the laser beam that has passed through the photomask is projected in a reduced size onto the irradiation object.
(19) A method for manufacturing a substrate mounted with an irradiation object, comprising irradiating a laser beam toward a donor substrate on which the irradiation object is provided, and moving the irradiation object from the donor substrate to a receptor substrate, wherein the laser beam is scanned by a scanning mirror and focused on a photomask as an image plane of an infinity corrected optical system, and the laser beam that has passed through the photomask is projected in a reduced size onto the irradiation object.
(20) A scanning type reduction projection optical system used in a laser processing device that irradiates an irradiation object with laser light to induce a reaction, comprising:
A scanning type reduction projection optical system having a first lens array, a second lens array, a scanning mirror, and a photomask.
(21) The scanning type reduction projection optical system according to (20), wherein the first lens array or the second lens array is formed by arranging lens elements.
(22) The scanning reduction projection optical system according to (21), wherein the lens element is of a fly-eye type, a cylindrical type or a spherical type.
(23) The scanning type reduction projection optical system according to any one of (20) to (22), wherein the first lens array or the second lens array is a combination of uniaxial cylindrical lenses arranged at right angles.
(24) The scanning type reduction projection optical system according to any one of (20) to (23), further comprising an array mask disposed immediately before the first lens array.
(25) The scanning type reduction projection optical system according to any one of (20) to (24), further comprising an array mask disposed between the first lens array and the second lens array.
(26) The scanning type reduction projection optical system according to (24) or (25), wherein the array mask has a group of apertures.
(27) The scanning type reduction projection optical system according to (26), wherein the openings forming the group of openings have a circular, elliptical, square or rectangular shape.
(28) The scanning reduction projection optical system according to (26) or (27), wherein the size of the apertures forming the aperture group is smaller than the size of the lens elements.
(29) The scanning type reduction projection optical system according to any one of (24) to (28), wherein the array mask has at least two types of aperture groups.
(30) The scanning reduction projection optical system according to (29), wherein the at least two types of aperture groups differ from each other in the size of the apertures forming each aperture group, the shape of the apertures, the number of apertures, or the arrangement of the apertures.
(31) A scanning type reduction projection optical system used in a laser processing device that irradiates an irradiation object with laser light to induce a reaction, comprising:
A scanning reduction projection optical system in which only the image side is telecentric.
(32) A method for removing a defective portion, comprising irradiating a laser beam toward a defective portion of a donor substrate having the defective portion, and removing the defective portion from the donor substrate, the method comprising the steps of:
A method for removing a defective portion, comprising irradiating the defective portion with a laser beam using a scanning type reduction projection optical system having a galvano scanner and a photomask.
(33)
The method for removing a defective portion according to (32), wherein the photomask has openings in a circular, elliptical, square or rectangular shape.
(34) The method for removing a defective portion according to (32) or (33), wherein the photomask has an area in which openings are arranged in a matrix.
(35) The method for removing a defective portion according to any one of (32) to (34), wherein the photomask has at least two types of opening groups.
(36) The method for removing a defective portion according to (35), wherein the at least two types of opening groups are different from each other in the size of the openings, the shape of the openings, the number of the openings, or the arrangement of the openings forming each opening group.
(37) A retransfer method comprising: irradiating a laser beam onto a donor substrate on which an irradiation object is provided, and transferring the irradiation object from the donor substrate to a receptor substrate, the retransfer method comprising the steps of:
the receptor substrate has an area where the irradiation object is mounted in advance and a defective area where the irradiation object is not mounted in the planned mounting area;
A retransfer method comprising: irradiating a laser beam onto an irradiation object provided on the donor substrate using a scanning type reduction projection optical system having a galvanometer scanner and a photomask; and moving the irradiation object to the defective area of the receptor substrate.
(38) A lifting method for irradiating a laser beam onto a donor substrate on which an irradiation object is provided, and moving the irradiation object from the donor substrate to a receptor substrate, comprising the steps of:
The irradiation object provided on the donor substrate has a defective area,
A lifting method comprising the steps of: irradiating an irradiation object other than the defective area with a laser beam using a scanning type reduction projection optical system having a galvano scanner and a photomask; and moving the irradiation object to the receptor substrate.

Each of the constituent elements in many of the above-mentioned embodiments can be subdivided, and the subdivided constituent elements can be introduced into these (1) to (38) either alone or in combination. Representative examples include the use and arrangement of various lenses, the type of laser light, various configurations and control methods in laser processing equipment, the type and shape of photomasks, the shape and arrangement of openings, the type and shape of the object to be irradiated, the reaction mechanism of laser lift-off, and the mechanism of the optical system.

It can be used as part of the manufacturing process for micro LED displays.

Claims (14)

A laser processing method for inducing a reaction by irradiating a laser beam onto an irradiation object, comprising:
A laser processing method comprising the steps of: irradiating the irradiation object with a laser beam using a scanning type reduction projection optical system having a photomask with at least two types of opening groups. The laser processing method according to claim 1, wherein the photomask has a circular, elliptical, square or rectangular opening. The laser processing method according to claim 1 or 2, wherein the photomask has an area in which the openings are arranged in a matrix. The laser processing method according to any one of claims 1 to 3, wherein the at least two types of opening groups differ from each other in the size of the openings, the shape of the openings, the number of openings, or the arrangement of the openings that form each opening group. The laser processing method according to any one of claims 1 to 4, wherein the reaction includes at least one reaction selected from the group consisting of a mechanical reaction, an optical reaction, an electrical reaction, a magnetic reaction, and a thermal reaction. A photomask for use in a laser processing method in which a laser beam is irradiated onto an irradiation object to induce a reaction, comprising:
A photomask having at least two types of openings. The photomask of claim 6 has circular, elliptical, square or rectangular openings. The photomask according to claim 6 or 7, which has an area in which the openings are arranged in a matrix. The photomask according to any one of claims 6 to 8, wherein the at least two types of opening groups differ from each other in the size of the openings forming each opening group, the shape of the openings, the number of openings, or the arrangement of the openings. A laser processing system that irradiates a laser beam toward an irradiation object to induce a reaction,
A laser processing system comprising: an optical system for irradiating a laser beam toward a substrate on which an object to be irradiated is provided; and a photomask having at least two types of opening groups. The laser processing system of claim 10, wherein the photomask has a circular, elliptical, square or rectangular opening. The laser processing system according to claim 10 or 11, wherein the photomask has an area in which the openings are arranged in a matrix. The laser processing system according to any one of claims 10 to 12, wherein the at least two types of aperture groups differ from each other in the size of the apertures forming each aperture group, the shape of the apertures, the number of apertures, or the arrangement of the apertures. The laser processing system according to any one of claims 10 to 13, wherein the reaction includes at least one reaction selected from the group consisting of a mechanical reaction, an optical reaction, an electrical reaction, a magnetic reaction, and a thermal reaction.

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