WO2012046478A1

WO2012046478A1 - Laser lift-off method and laser lift-off device

Info

Publication number: WO2012046478A1
Application number: PCT/JP2011/064643
Authority: WO
Inventors: 僚三松田; 恵司鳴海
Original assignee: ウシオ電機株式会社
Priority date: 2010-10-06
Filing date: 2011-06-27
Publication date: 2012-04-12
Also published as: TW201221268A

Abstract

The present invention prevents, to the maximum extent possible, the occurrence of cracking in a material layer following separation from a substrate, and enables laser lift-off treatment to be performed in a short period of time. In order to separate a material layer (2) at the interface of a substrate (1) and the material layer (2), a pulsed laser beam is emitted through the substrate (1) while altering the irradiation area over time. The laser beam is formed in rectangular shapes having at least one side extending in a direction parallel to the direction of movement of a workpiece (3), is emitted so that each of the adjacent irradiated areas overlap with one another, and is irradiated on a workpiece (3) so that within the rectangular separation regions of the material layer (2), two sides of the material layer are initially separated from the substrate (1). Thus, the N₂ gas generated by the decomposition of GaN can escape from the two sides where separation has been completed, enabling separation of the material layer (2) without cracking. Furthermore, using a mask to split the laser beam into a plurality of laser beams irradiating smaller areas, and thereby creating a plurality of irradiation areas spaced apart from one another on the workpiece enables laser lift-off treatment to be performed in a short period of time.

Description

Laser lift-off method and laser lift-off apparatus

In the manufacturing process of a semiconductor light emitting device formed of a compound semiconductor, the present invention decomposes the material layer by irradiating the material layer formed on the substrate with a laser beam, and peels the material layer from the substrate (hereinafter referred to as the following). The present invention relates to a laser lift-off method and a laser lift-off apparatus.

Laser for peeling a GaN-based compound material layer formed on a sapphire substrate by irradiating a laser beam from the back surface of the sapphire substrate in a manufacturing process of a semiconductor light-emitting device formed of a GaN (gallium nitride) -based compound semiconductor Lift-off technology is known. Hereinafter, the process of irradiating the material layer formed on the substrate with laser light and peeling the crystal layer from the substrate is referred to as laser lift-off.
For example, in Patent Document 1, a GaN layer is formed on a sapphire substrate, and laser light is irradiated from the back surface of the sapphire substrate, whereby GaN forming the GaN layer is decomposed, and the GaN layer is separated from the sapphire substrate. A laser lift-off method for peeling is described. Hereinafter, a substrate in which a crystal layer is formed on a substrate is referred to as a workpiece.
In order to laser lift off the GaN-based compound material layer from the substrate, the entire surface of the workpiece is irradiated with laser light having irradiation energy equal to or higher than the decomposition threshold necessary for decomposing the GaN-based compound into Ga and N _2. Becomes important.

Patent Document 2 describes that a workpiece is irradiated with a line-shaped laser beam through a sapphire substrate while the workpiece is conveyed. Specifically, in this document, as shown in FIG. 27, a laser beam 124 is formed so that an irradiation region 123 to the interface between the sapphire substrate 121 and the material layer 122 of the GaN-based compound is formed in a line shape, and the sapphire substrate 121 A laser lift-off method is disclosed in which the laser beam 124 is irradiated from the back surface of the sapphire substrate 121 while moving the laser beam 124 in a direction perpendicular to the longitudinal direction of the laser beam 124.
Further, in Patent Document 3, for example, a rectangular beam spot is formed using a laser, and the irradiated object is sequentially irradiated while moving the beam spot, and the material layer is laser lifted off from the substrate. Is described. FIG. 17 of Patent Document 3 shows that the beam spot 132 is moved concentrically with respect to a circular workpiece (wafer 131) and laser lift-off is performed as shown in FIG.

JP-T-2001-501778 JP 2003-168820 A Special Table 2007-534164

As described above, when the GaN-based compound material layer formed on the sapphire substrate is peeled off by irradiating the laser beam from the back surface of the sapphire substrate, the GaN is decomposed when irradiated with the laser beam. The N ₂ gas that is applied causes shear stress to the GaN layer, which may cause cracks at the boundary of the laser light irradiation region.
In laser lift-off, it is important to prevent such cracks from occurring in the material layer after peeling.
As a laser light irradiation method, for example, as described in Patent Document 2, the laser light is shaped so that the irradiation region to the interface of the material layer is in a line shape, and the substrate is formed in a direction perpendicular to the longitudinal direction of the laser light. A method of irradiating a laser beam while scanning it, or scanning a rectangular beam spot concentrically with respect to a circular wafer as described in Patent Document 3, and irradiating while changing the irradiation area every time has been proposed. ing.
The method described in Patent Document 2 is to form an irradiation region in a line shape and irradiate while moving the irradiation region in the direction perpendicular to the longitudinal direction of the laser beam, and the laser beam corresponds to the width of the substrate. Although it is required to be shaped into a long shape, it is difficult to obtain a laser beam having such a shape with a large irradiation illuminance and cannot be realized easily.
Further, as described in FIG. 17 of Patent Document 3, in order to scan the beam spot, a mechanism for moving the square beam spot relatively concentrically on the work is necessary, and overlapping is required. The area of the irradiated region increases, and it is considered that a long time is required to irradiate the entire area of the workpiece with laser light, which is not efficient.

In addition, the inventors previously changed the position of the irradiation area of the laser beam having a small area formed in a square shape, while the end of each irradiation area overlaps the end of the adjacent irradiation area. The laser lift-off method is proposed. In this way, as shown in Patent Document 2, the laser beam is efficiently and cracked without forming a long and narrow shape and using a special mechanism for scanning the beam spot concentrically. The laser lift-off can be realized without causing it.
However, even when the laser light having a small area formed into a quadrangular shape as described above is irradiated while changing the irradiation region, cracks may occur in the material layer after peeling from the substrate.

In the laser lift-off process described above, the time required for laser lift-off (that is, the time required for irradiating the entire surface of the workpiece with laser light) mainly depends on the laser light irradiation area and the workpiece conveyance speed. To do. Naturally, the irradiation time of the laser beam required for processing the workpiece becomes shorter if the irradiation area of the laser beam to the workpiece is large and the workpiece is conveyed at a high speed, and becomes longer if the workpiece is transferred at high speed.
However, there is a limit to the workpiece transfer speed. Therefore, the time required for laser lift-off mainly depends on the irradiation area of the laser beam on the workpiece. However, increasing the irradiation area of the laser beam on the workpiece involves various difficulties as will be described below.
That is, the laser light used for laser lift-off requires irradiation energy exceeding the decomposition threshold for decomposing the material constituting the material layer, but the laser light is maintained while maintaining the irradiation energy necessary for laser lift-off. It is difficult to increase the irradiation area.
As a result of intensive studies by the present inventors, it has been found that when the laser light irradiation area on the workpiece is increased, damage such as cracks occurs in the material layer at the time of laser lift-off.
As described above, the material layer is irradiated with pulsed laser light, whereby GaN in the material layer is decomposed into Ga and N ₂ . Since N ₂ gas is generated by the decomposition of GaN, shear stress is applied to the GaN layer, and cracks are generated at the boundary of the laser light irradiation region, thereby damaging the edge of the irradiation region.
It is considered that the magnitude of damage due to this decomposition greatly depends on the irradiation area of the laser beam. That is, as the irradiation area S is larger, a larger force is applied to the edge portion of the irradiation region of the pulsed laser light, such as the generation amount of the N ₂ gas is increased.

For the reasons described above, it is desirable to reduce the irradiation area of the laser beam on the workpiece in order to reduce damage to the material layer at the time of laser lift-off.
However, when the laser light irradiation area is reduced, there is a problem that the laser light irradiation time required for laser lift-off becomes longer. For example, under the following condition 1, the irradiation time of laser light required for laser lift-off of a workpiece of φ2 inches (50.8 mm) is about 25 seconds. On the other hand, under the following condition 2, the irradiation time of the laser beam required for laser lift-off of the φ2 inch workpiece is about 625 seconds.
(Condition 1)
・ Workpiece diameter: φ2 inch ・ Laser irradiation area: 1 mm square ・ Pulse laser light frequency: 100 Hz
(Condition 2)
・ Workpiece diameter: φ2 inches ・ Laser irradiation area: 0.2 mm square ・ Pulse laser light frequency: 100 Hz
As described above, in order to sufficiently peel the material layer from the substrate without causing damage, it is necessary to reduce the irradiation area of the laser beam. However, since it is necessary to irradiate the entire surface of the workpiece with the laser beam, the time required for the laser lift-off process increases when the area of the laser beam irradiation region is reduced.

On the other hand, as a result of intensive studies by the present inventors, in order to laser lift off the GaN-based compound material layer from the substrate, irradiation energy equal to or higher than the decomposition threshold necessary for decomposing the GaN-based compound into Ga and N ₂ is required. It was found that it is necessary to irradiate the entire surface of the workpiece with the laser beam.
If there is a region where a laser beam having irradiation energy equal to or higher than the decomposition threshold is not irradiated, an undecomposed region of GaN constituting the material layer is formed, and the material layer cannot be sufficiently separated from the substrate. For this reason, the edge part of an adjacent irradiation area | region needs to overlap in the energy area | region exceeding the decomposition threshold value VE.

As described above, in order to sufficiently peel the material layer from the substrate without causing damage, the laser light is applied to the workpiece so that the edge portion of the adjacent irradiation region overlaps in the energy region exceeding the decomposition threshold VE. It is necessary to irradiate the entire surface, but in addition to this, it is necessary to reduce the irradiation area of the laser beam.
However, when the irradiation area of the laser beam is reduced, there is a problem that the time required for the laser lift-off process increases as described above. Further, even when the laser beam is irradiated in this manner, cracks may occur in the material layer after peeling from the substrate depending on the laser beam irradiation method as described above.

The present invention solves the above-mentioned problems, can prevent the generation of cracks in the material layer after peeling from the substrate as much as possible, and can perform laser lift-off processing in a short time with a laser beam having a small irradiation area. It is an object of the present invention to provide a laser lift-off method and apparatus capable of performing the above.

As a result of various studies by the present inventors, as described above, the end of each irradiation region overlaps with the end of the adjacent irradiation region while changing the irradiation region of the laser beam formed into a square shape as described above. It was found that the material layer can be peeled from the substrate while preventing the generation of cracks by irradiating the substrate.
However, it has been found that even with the laser lift-off method, cracks may occur in the material layer after peeling from the substrate, depending on the method of irradiating the workpiece with laser light. This will be described below.
FIG. 6 shows that the material layer is formed by irradiating the workpiece with laser light so that the edge portions of the irradiation region of the laser beam are sequentially superimposed in accordance with the conveyance direction of the workpiece while changing the irradiation region with respect to the workpiece. Shows a method of laser lift-off from the substrate.
This figure shows the case where the irradiation area of the laser beam on the workpiece is square (square). The black area in the figure is the irradiation area irradiated with the laser beam, and the shaded area is the laser beam. The irradiated area and the white part are areas where the laser beam has not been irradiated, and the irradiated area is sequentially moved in the direction indicated by the arrow in the figure, and the laser beam is irradiated while changing the irradiation area every moment.
Moreover, in the same figure, when the peeling side of the material layer peeled for the first time from the substrate is two sides in the rectangular peeling region of the material layer peeled from the substrate (two-side peeling in FIG. 1A). , And the case of three sides (three-side peeling in FIG. 1B) and the case of one side (one-side peeling in FIG. 1C) are shown.

FIG. 7 is an image showing the state of the material layer peeled off by the laser lift-off method shown in FIG. 6, and the state after peeling from the substrate when the laser lift-off is performed as shown in FIGS. It shows the presence or absence of occurrence of cracks in the material layer.
FIG. 7 shows a case where the GaN-based compound material layer formed on the sapphire substrate is peeled off by irradiating the rectangular laser beam shown in FIG. 6 from the back surface of the sapphire substrate. (A) shows the case where the peeling side of the material layer peeled from the substrate for the first time is two sides (FIG. 6A), and FIG. 7B shows the case where there are three sides (FIG. 6B). FIG. 7C shows the case of one side (FIG. 6C).

As shown in FIG. 6A, when two sides were peeled for the first time from the undecomposed region of the material layer, cracks did not occur as shown in FIG. As shown in FIG. 7, when three sides were peeled for the first time from the undecomposed region of the material layer, cracks occurred in the peeled material layer as shown in FIG.
The reason is considered as follows.
GaN, which is a material layer, is decomposed into Ga and N ₂ when irradiated with laser light. As shown in FIGS. 6 (a) and 6 (b), the N ₂ gas generated during the decomposition of GaN is not discharged from the side in contact with the undecomposed region of GaN in a rectangular separation region that is sequentially separated from the substrate. Since it is possible, it is discharged from the side already peeled off from the substrate.
In rectangular peeled area of GaN as shown in FIG. 6 (a), if the first time peeled edges from the substrate is two sides, already in two sides peeling already sides from the substrate, escape of N ₂ gas Since these are the two sides and the N ₂ gas escapes from these two sides, no large gas pressure is applied to the region irradiated with light.
On the other hand, as shown in FIG. 6B, in the GaN square-shaped peeling region, when the side peeled for the first time from the substrate is three sides, there is only one side already peeled from the substrate, N ₂ escape of gas is only the one side. For this reason, N ₂ gas cannot be sufficiently discharged, and stress generated by the pressure of N ₂ gas accumulates on three sides in contact with the undecomposed region of GaN in the material layer peeled from the substrate, It is considered that cracks occur in the GaN after peeling from the substrate.

As shown in FIG. 7C, even when the side peeled for the first time from the undecomposed region of the material layer is one side, as shown in FIG. Cracks occurred.
In this case, as shown in FIG. 6C, there are three sides already peeled from the substrate, so there is no problem with the discharge of N ₂ gas. However, since the stress generated when GaN is decomposed by laser light irradiation is concentrated only on one side in contact with the undecomposed region of GaN, when the strength of the material layer is not sufficient, It is thought that cracks occur.
As shown in FIG. 6 (c), the upper and lower regions are already peeled regions, and an undecomposed region remains between them. It is a special case that the undecomposed region is irradiated with laser light. Although this does not occur when laser light is irradiated in order from one end of the workpiece to the other end, such a case may occur depending on the method of irradiating the workpiece with laser light. FIG. It is desirable to avoid the “one-side peeling” shown in FIG.

As described above, the irradiation region of the laser beam on the workpiece has a quadrangular shape having one side extending in a direction parallel to the movement direction of the workpiece, and the material layer peeled from the substrate by irradiating the workpiece with the laser beam. By making the sides peeled for the first time from the substrate into two sides in the square peeled region, it is possible to prevent the material layer after peeling from being cracked.
That is, as shown in FIG. 6A, when there are two sides peeled from the substrate for the first time, no cracks are generated in the GaN after peeling from the substrate as shown in FIG. 7A. It was.
This is because, in the GaN quadrilateral peeling region, when there are two sides peeled off from the substrate for the first time, N2 gas generated by the decomposition of GaN is discharged from the two sides already peeled off from the substrate, and N _This is because a sufficient escape path for _two gases is secured.
In addition, when the peeled sides are two sides, the stress generated when GaN is decomposed by laser light irradiation is distributed and applied to the two sides in contact with the undecomposed region of GaN, thereby causing cracks. Occurrence is prevented.

In order to ensure a sufficient escape path for N ₂ gas and to disperse the stress generated when GaN decomposes, in the peeling region where the GaN is sequentially peeled from the substrate by the irradiation of the laser beam, the peeling is performed for the first time from the substrate. The ratio of the total length X of the sides to the total length Y of the sides already peeled from the substrate is preferably about 1: 1.
In other words, the two sides that are peeled off from the substrate for the first time are always kept in harmony between ensuring the escape path of the gas generated during decomposition of the material layer and dispersing the stress generated during decomposition of the material layer. This can be achieved well, and the occurrence of cracks in the material layer after peeling from the substrate can be prevented or suppressed.

In addition, in order to enable laser lift-off processing to be performed in a short time with a laser beam having a small irradiation area, in the present invention, as described above, in each irradiation region, the sides to be peeled for the first time are two sides. Is irradiated with laser light, and the laser light is divided so that the plurality of irradiation regions separated from each other are formed on the workpiece while relatively moving the workpiece or the laser source (irradiation region). Irradiate light in a lump.

In other words, the workpiece is irradiated with laser light as follows.
Using a laser beam forming means provided with a plurality of laser beam emitting sections with a small area for dividing the laser beam, such as a mask, the laser beam emitted from the laser source is divided into a plurality of laser beams on the workpiece. A plurality of irradiation regions with small areas separated from each other are formed. Here, the region irradiated with each laser beam emitted from the plurality of laser beam emitting units is referred to as an irradiation region.
Then, while moving the workpiece or the laser source (irradiation region) relatively, the laser beam is collectively irradiated so that the plurality of irradiation regions separated from each other are formed on the workpiece.
At that time, the adjacent irradiation regions are spaced apart from each other so as to be arranged obliquely with respect to the movement direction of the workpiece, and the end portions extending in a direction parallel to the relative movement direction of the workpiece in the adjacent irradiation region, The plurality of irradiation areas are arranged so as to be sequentially overlapped as they move. Furthermore, the conveyance speed of the workpiece 3 and the irradiation interval of the pulse laser light are set so that the edge portions extending in the direction orthogonal to the workpiece conveyance direction in each irradiation region overlap each other.
That is, the end portions (edge portions) of the respective irradiation regions overlap with the end portions (edge portions) of the adjacent irradiation regions.
In this way, it is substantially the same as having a large laser irradiation area on the workpiece, and a laser lift-off process can be performed in a short time.
Note that the laser beam that is superimposed and irradiated on the workpiece is irradiated with a slight interval since the workpiece is moved relative to the laser source. The material layer (GaN) has a very short time to return to room temperature after reaching the temperature at which the material layer decomposes. On the other hand, the irradiation interval of the laser light that is superimposed and irradiated on the workpiece is much longer than the time required to return to room temperature after reaching the temperature at which the material layer is decomposed. Therefore, in the region where the laser beam is superimposed, the irradiation energy of each laser beam is not summed up, so the irradiation region of the laser beam emitted from each laser beam emitting section is substantially small, and damage to the material layer is reduced. The

Based on the above, the present invention solves the above problems as follows.
(1) A workpiece having a material layer formed on a substrate is irradiated with a laser beam from a laser source through the substrate, and the material layer is decomposed at the interface between the substrate and the material layer. In the laser lift-off method for peeling, the laser beam is irradiated to the workpiece while changing the irradiation region to the workpiece, and the irradiation region of the laser beam to the workpiece extends in a direction parallel to the moving direction of the workpiece. The edges of the irradiation area are sequentially superimposed as the workpiece moves in one direction relative to the laser source, and the laser light is sequentially emitted from the substrate. The workpiece is irradiated so that the peeling side of the material layer peeled off for the first time from the substrate becomes two sides in the square peeling region of the peeled material layer. .
(2) In the above (1), each irradiation region group is formed by laser light so as to be sequentially arranged from one end to the other end of the workpiece, and the irradiation region group formed first and last in the workpiece. The irradiated region group is formed so as to extend from one edge portion and the other edge portion of the workpiece.
(3) In the above (1), the laser beam emitted from the laser source is divided into a plurality of laser beams, and a plurality of irradiation regions separated from each other are formed on the workpiece by the divided pulse laser beams, The plurality of irradiation areas are sequentially overlapped with the ends of the adjacent irradiation areas extending in a direction parallel to the movement direction of the work as the work moves in one direction relative to the laser source. Arranged.
(4) In a laser lift-off device that irradiates a workpiece having a material layer formed on a substrate with laser light through the substrate and peels the material layer from the substrate at an interface between the substrate and the material layer. A laser source that generates laser light in a wavelength region that passes through the substrate, a transport mechanism that relatively transports the work and the laser source, and the laser light changes the irradiation area of the work every moment, As the irradiation area is sequentially irradiated from one end to the other end of the work, the work is irradiated, and the edge of the irradiation area moves in one direction relative to the laser source. The laser beam emitted from the laser source and the control unit for controlling the irradiation interval of the laser beam and the transfer operation of the workpiece by the transfer mechanism so as to be sequentially superimposed It is formed into a square shape having one sides extending in the moving direction and the direction parallel click, providing a laser optical system for irradiating the workpiece.
The control unit irradiates the workpiece with laser light so that an irradiation region group formed first and an irradiation region group formed last in the workpiece extend from one edge portion and the other edge portion of the workpiece. At the same time, the workpiece is irradiated with the laser light so that the material layer to be peeled for the first time from the substrate has two sides of the square peeled region of the material layer that has been sequentially peeled from the substrate. To do.
(5) In the above (4), the laser beam emitted from the laser source is divided into a plurality of laser beams, and a plurality of irradiation regions separated from each other are formed on the workpiece by the divided pulse laser beams. A plurality of irradiation regions formed by the laser beam forming unit, the end portions extending in parallel to the moving direction of the workpiece in the adjacent irradiation regions, and the workpiece is relative to the laser source; Thus, they are arranged so that they are sequentially superimposed as they move in one direction.
(6) In the above (5), a mask having a plurality of rectangular openings is used as the laser beam forming means.
(7) In the above (5) or (6), the irradiation areas formed on the workpiece are arranged on a straight line inclined in the moving direction of the workpiece.
(8) In the above (6), the mask includes one mask pattern arranged on a straight line on each of the virtual line and the virtual line intersecting the plurality of openings, and the other mask pattern. The openings of the mask are arranged in an X shape.
(9) In the above (8), a mask shutter that opens and closes the plurality of openings of the mask is provided, and the mask shutter opens only the opening of the one mask pattern when the workpiece is transported. Except for the opening located at the intersection of the imaginary line and the other imaginary line, the opening of the other mask pattern is opened and closed so as to be closed, and the mask shutter is changed every 180 ° in the conveyance direction of the workpiece, Except for the opening located at the intersection of the one virtual line and the other virtual line, the open / closed states of the one mask pattern and the other mask pattern are switched.
(10) In the above (6), the mask includes one mask pattern including a plurality of openings arranged on one imaginary line and the other mask pattern including a plurality of openings arranged on the other imaginary line. The openings of the mask are arranged in a V shape.
(11) In the above (10), the mask includes a mask transport mechanism that transports the mask so that only one of the one mask pattern and the other mask pattern is disposed in the laser light irradiation region. The mask transport mechanism switches the mask pattern arranged in the laser light irradiation region every time the work transport direction is switched by 180 °.

In the present invention, the following effects can be obtained.
(1) Since the material layer peeled from the substrate for the first time in the square peeled region of the material layer peeled sequentially from the substrate has two peeled sides, N generated by the decomposition of GaN _Two gases are discharged from the two sides already peeled from the substrate, and a sufficient escape path for N ₂ gas can be secured. In addition, when there are two separated sides, the stress generated when GaN is decomposed by laser light irradiation is distributed and applied to the two sides in contact with the undecomposed region of GaN, preventing the generation of cracks. Is done.
In addition, by irradiating the workpiece with laser light so that the irradiation region group formed first and the irradiation region group formed last in the workpiece extend from one edge portion and the other edge portion of the workpiece, Also in the irradiation region group formed at the beginning and the end of the workpiece, the sides to be peeled are two sides, and the sides to be peeled can be always two sides in the entire area of the workpiece.
(2) By moving the irradiation region of the laser beam linearly on the workpiece, the laser lift-off process can be performed on the entire area of the workpiece, and there is no need to use a special mechanism for scanning the laser beam. The configuration can be simplified.

(3) Laser light emitted from the laser source is divided into a plurality of laser beams by the laser beam forming means, and a plurality of irradiation areas separated from each other are formed on the workpiece by each of the divided laser beams. Since each of the irradiation areas is collectively irradiated with the laser beam, it is possible to irradiate the plurality of irradiation areas with a single laser beam irradiation. That is, since a plurality of irradiation regions can be irradiated with laser light at once, even if each irradiation region is small in area, laser lift-off processing can be performed in a short time, and throughput can be improved. .
(4) The edge of the laser beam emitted from each of the adjacent laser beam emitting portions is superimposed on the workpiece in the direction orthogonal to the moving direction of the workpiece in order, and the workpiece conveying direction in each irradiation region. Since the edge portions in the orthogonal direction overlap each other, the laser light having irradiation energy equal to or higher than the decomposition threshold necessary for decomposing the GaN-based compound into Ga and N ₂ is reduced while reducing each irradiation area. The entire surface of the work can be irradiated.
Further, as described above, since the laser light irradiated on the overlap region is irradiated with a time interval sufficient for the temperature of the irradiated region to decrease, each irradiation of the laser light irradiated on the overlap region is performed. Energy is never added up. Therefore, even if the respective irradiation regions are overlapped, the same effect as that obtained by irradiating the laser light substantially for each irradiation region can be obtained. For this reason, damage to the material layer when the material layer is peeled from the substrate can be reduced.

It is a conceptual diagram explaining the outline | summary of the laser lift-off process of 1st Example of this invention. It is a figure which shows a mode that a laser beam is irradiated to a workpiece | work. It is a figure explaining the edge | side peeled from a board | substrate for the first time becomes two sides. It is a conceptual diagram of the laser lift-off apparatus of the 1st Example of this invention. It is a figure which shows the light intensity distribution of the laser beam irradiated in the 1st Example of this invention superimposed on the area | region S1, S2 which a workpiece | work mutually adjoins. It is a figure explaining the case where a laser beam is irradiated so that a GaN undecomposed area | region may become 2 sides, 3 sides, and 1 side. It is the figure which showed typically the surface state of the material layer after peeling at the time of irradiating a laser beam so that a GaN undecomposed area | region may become 2 sides, 3 sides, and 1 side. FIG. 3 is a diagram showing an outline of the configuration of a laser lift-off device according to second to fourth embodiments of the present invention. FIG. 5 is a conceptual diagram of an optical system of a laser lift-off device according to second to fourth embodiments of the present invention. It is a figure which shows the mask used for the laser lift-off apparatus of the 2nd Example of this invention. It is a figure explaining the laser beam irradiation method which concerns on the laser lift-off apparatus of the Example of the 2nd Example of this invention. It is a figure which shows the scanning direction of the laser beam on the workpiece | work of the 2nd Example of this invention, and the irradiation pattern of the laser beam to a workpiece | work. It is a time chart which shows the irradiation of a laser beam and the timing of a pause in 2nd Example of this invention. It is a figure which shows the relationship between the irradiation timing of the pulse laser beam in a 2nd Example, and the irradiation area | region on a workpiece | work. It is a conceptual diagram of the optical system of the laser lift-off apparatus of the modification of a 2nd Example. It is a figure which shows the structural example of the laser beam formation means shown in FIG. It is a figure which shows the mask used for the laser lift-off apparatus of the 3rd Example of this invention. It is a figure which shows operation | movement of the mask shutter for opening and closing the opening of the mask of the 3rd Example of this invention. It is a figure explaining the laser beam irradiation method which concerns on the laser lift-off apparatus of a 3rd Example. It is a figure which shows the scanning direction of the laser beam on the workpiece | work of a 3rd Example, and the irradiation pattern of the laser beam to a workpiece | work. It is a time chart which shows the timing of the irradiation of a laser beam and a rest in a 3rd Example. It is a figure which shows the mask used for the laser lift-off apparatus of the 4th Example of this invention. It is a figure explaining the laser beam irradiation method which concerns on the laser lift-off apparatus of a 4th Example. FIG. 10 is a diagram showing a mask transport mechanism for moving a mask in the fourth embodiment. It is a time chart which shows the timing of the irradiation of a laser beam and a rest in a 4th Example. It is a figure explaining the manufacturing method of the semiconductor light-emitting device which can apply a laser lift-off process. It is a figure which shows the prior art example irradiated while moving a line-shaped laser beam to the orthogonal | vertical direction with the longitudinal direction of a laser beam. It is a figure which shows the prior art example irradiated while moving a square-shaped beam spot concentrically.

(1) 1st Example FIG. 1: is a conceptual diagram explaining the outline | summary of the laser lift-off process of the 1st Example of this invention.
As shown in the figure, in the present embodiment, the laser lift-off process is performed as follows.
A work 3 in which a material layer 2 is formed on a substrate 1 that transmits laser light is placed on a work stage 31. The work stage 31 on which the work 3 is placed is placed on a transport mechanism 32 such as a conveyor, and is transported by the transport mechanism 32 at a predetermined speed. The workpiece 3 is irradiated with a pulse laser beam L emitted from a pulse laser source (not shown) through the substrate 1 while being conveyed in the arrow AB direction in the figure together with the workpiece stage 31.
The workpiece 3 is formed by forming a material layer 2 of a GaN (gallium nitride) compound on the surface of a substrate 1 made of sapphire. The substrate 1 may be any material that can satisfactorily form a GaN-based compound material layer and transmits laser light having a wavelength necessary for decomposing the GaN-based compound material layer. A GaN-based compound can be used for the material layer 2 in order to efficiently output high-output blue light with low input energy. As the material layer 2, a group III compound can be used, such as the GaN compound, indium gallium nitride (InGaN) compound, aluminum gallium nitride (AlGaN) compound, or the like.

The laser beam should be appropriately selected according to the substrate 1 and the substance constituting the material layer peeled from the substrate 1. When the GaN-based compound material layer 2 is peeled from the sapphire substrate 1, for example, a KrF (krypton fluorine) excimer laser that emits a wavelength of 248 nm can be used. The light energy (5 eV) with a laser wavelength of 248 nm is between the band gap of GaN (3.4 eV) and the band gap of sapphire (9.9 eV). Therefore, a laser beam having a wavelength of 248 nm is desirable for peeling the material layer of the GaN compound from the sapphire substrate.

When the material layer 2 is irradiated with pulsed laser light, GaN in the material layer 2 is decomposed into Ga and N ₂ . When GaN decomposes, a phenomenon as if it has exploded occurs, and the edge of the irradiation region of the pulse laser beam on the material layer 2 is damaged to some extent.
In the laser lift-off process of the present invention, since the material layer that is peeled off from the substrate for the first time is made to have two sides, the laser lift-off process is performed without damaging the material layer as described above. It can be carried out.

In the present invention, the shape of the irradiation region of the pulse laser beam irradiated to the workpiece is a quadrangle having one edge portion extending in parallel with the moving direction of the workpiece at the time of pulse laser beam irradiation. The laser light irradiation region may have any shape as long as it has a rectangular shape. However, due to the structure of the laser device, when the aspect ratio of the irradiation region is 1: X, X is 20 or less, and the area of the irradiation region is It is desirable that it be 30 mm ² or less. In addition, when the shape of the irradiation region is a rectangle that is greatly different in length and width as described above, it is considered desirable to scan the irradiation region mainly along the short side.
FIG. 2 below shows an irradiation region by the laser lift-off method of the present embodiment, in which pulsed laser light shaped so that the irradiation region on the workpiece is square is irradiated while the workpiece is conveyed in one direction with respect to the laser source. Show. Although FIG. 1 shows the case where the workpiece is rectangular, FIG. 2 shows the case where the workpiece 3 is circular.
In this laser lift method, by adjusting the irradiation interval of the pulse laser light and the conveyance speed of the workpiece 3, an edge portion extending in a direction parallel to the moving direction of the workpiece 3 in the irradiation region of the rectangular pulse laser light, In addition, the workpiece 3 is irradiated with pulsed laser light so that both edges extending in the direction orthogonal to the moving direction of the workpiece (direction C in FIG. 1) overlap.
In the laser lift-off method of FIG. 2, the pulse laser beam is sequentially irradiated so that each irradiation region is arranged in a line in the direction of HA on the paper surface so as to exceed the edge portion above the paper surface of the work 3. Light irradiation regions S1 to S4 are formed. Then, after moving the workpiece 3 in the HB direction below the paper surface by the amount of the laser laser irradiation region ST subtracted from the size of the pulse laser irradiation region, each irradiation region emits the pulse laser light toward the HC direction on the paper surface. Irradiation is sequentially performed so as to form a line, and pulsed laser light irradiation regions S5 to S10 are formed.

As shown in FIG. 2A, the edge portions extending in the direction orthogonal to the moving direction of the workpiece 3 in the irradiation regions S1 to S10 adjacent in the moving direction of the workpiece 3 overlap each other. In addition, the edge portions extending in the direction parallel to the moving direction of the work 3 in the irradiation areas S1 and S9, S2 and S8, S3 and S7, and S4 and S6 adjacent in the direction orthogonal to the moving direction of the work 3 overlap each other. . In addition, as shown in FIG. 5 to be described later, the irradiation regions of the respective pulse laser beams are overlapped in regions exceeding the decomposition threshold value of GaN as the material layer. In this way, a plurality of irradiation region groups G1 to G6 are formed in which irradiation regions of a plurality of pulsed laser beams formed in sequence are formed in a line in one direction.
In the laser lift-off method of the present embodiment, the irradiation of the pulse laser beam is started from the one end 3a of the workpiece 3, and the pulse laser beam is finally irradiated to the other end 3b of the workpiece 3. That is, the irradiation region groups G1 to G6 are sequentially arranged from the one end 3a to the other end 3b of the workpiece 3 in the direction orthogonal to the relative movement direction of the workpiece with respect to the laser source in the order in which the laser beams are irradiated. Each irradiation region group is formed so as to line up.

In the irradiation region group G1 formed first in the workpiece 3, the irradiation regions S1 to S4 are irradiated with pulsed laser light so as to extend from one edge portion (one end) 3a of the workpiece 3. In the irradiation region group G6 formed last in the workpiece 3, the pulse laser beam is irradiated so that each irradiation region extends from the other edge (other end) 3b of the workpiece 3. By doing so, in the GaN square-shaped peeling region sequentially peeled from the substrate, as shown by a dotted line in FIG. 3, the edge portion peeled for the first time from the substrate always has two sides.
For example, in the irradiation region S1, since the sides other than the two edge portions that are peeled off from the substrate for the first time are in contact with the outer edge portion of the work 3 and are not undecomposed regions, N ₂ gas generated during GaN decomposition is discharged from the outer edge portion. Is done. Similarly the irradiated region S2 also, the first side of the non-edge portion of the two sides to be peeled from the substrate, the contact outer edge and the irradiation region S1 of the workpiece 3, N ₂ gas generated during GaN decomposition from the outer edge Discharged.

As described above, in this embodiment, the edge portion of the irradiation region is sequentially superimposed as the workpiece 3 moves in one direction relative to the laser source, and the laser light is sequentially emitted from the substrate. As shown in FIG. 6 (a), the workpiece 3 is irradiated with the peeled side of the material layer peeled off from the substrate for two sides in the square peeled area of the peeled material layer. . In addition, the irradiation region group formed first and the irradiation region group formed last in the workpiece 3 are formed so as to extend from one edge portion and the other edge portion of the workpiece 3.
On the other hand, in the comparative example shown in FIGS. 6B and 6C, as shown in FIG. 2, the irradiation region is irradiated by sequentially irradiating the laser beam from one end of the work 3 to the other end. Since the groups are not formed side by side, the edge part peeled off for the first time from the substrate does not always have two sides.
According to the laser lift-off method of the present embodiment, in the GaN square-shaped peeling region sequentially peeled from the substrate, the edge portion peeled off for the first time from the substrate is always two sides, as described above. The generation of cracks in GaN after peeling off can be prevented or suppressed. In addition, when the shape of the irradiation region of the pulse laser beam is a square, it is easy to overlap the peripheral portion of each irradiation region.
Note that, as described in Patent Document 3, if the irradiation region is moved concentrically (see FIG. 28), the edge portion peeled off from the substrate for the first time is considered to be a value close to two sides, In this case, as described above, a special mechanism for scanning the beam spot concentrically is necessary, and there are many overlapping portions of the irradiation region, resulting in poor efficiency, and depending on how the beam spot is moved, As shown in FIG. 6C, the edge portion that is peeled off from the substrate for the first time may be one side, and there is a possibility that a crack will occur at this portion.

FIG. 4 is a conceptual diagram showing the configuration of the optical system of the laser lift-off device according to the first embodiment of the present invention. In the figure, a laser lift-off device 10 includes a laser source 20 that generates pulsed laser light, a laser optical system 40 for shaping the laser light into a predetermined shape, a work stage 31 on which the work 3 is placed, A transport mechanism 32 that transports the work stage 31 and a controller 33 that controls the irradiation interval of the laser light generated by the laser source 20 and the operation of the transport mechanism 32 are provided.
The laser optical system 40 includes

cylindrical lenses

41 and 42, a mirror 43 that reflects the laser light in the direction of the workpiece, a mask 44 for shaping the laser light into a predetermined shape, and the laser light L that has passed through the mask 44. And a projection lens 45 for projecting an image onto the work 3. The area and shape of the irradiation region of the pulse laser beam on the work 3 can be appropriately set by the laser optical system 40.
A workpiece 3 is disposed at the tip of the laser optical system 40. The work 3 is placed on the work stage 31. The work stage 31 is placed on the transport mechanism 32 and is transported by the transport mechanism 32. Thereby, the workpiece | work 3 is conveyed sequentially in the direction of the arrows A and B shown in FIG. 1, and the irradiation area of the laser beam in the workpiece | work 3 changes every moment. The control unit 33 controls the pulse interval of the pulsed laser light generated by the laser source 20 so that the degree of superimposition of each laser light irradiated on the irradiation region adjacent to the workpiece 3 becomes a desired value.

The laser light L generated from the laser source 20 is, for example, a KrF excimer laser that generates ultraviolet light having a wavelength of 248 nm. An ArF laser or a YAG laser may be used as the laser source. Here, the light incident surface 3 A of the work 3 is disposed farther in the optical axis direction of the laser light than the focal point F of the projection lens 45. On the contrary, the light incident surface 3A of the workpiece 3 may be disposed closer to the projection lens 45 than the focal point F of the projection lens 45 in the optical axis direction of the laser light. Thus, by arranging the light incident surface 3A of the workpiece 3 so as not to coincide with the focal point F of the projection lens 45, a laser beam having a trapezoidal light intensity distribution as shown in FIG. It is done.
The pulsed laser light L generated by the laser source 20 passes through the

cylindrical lenses

41 and 42, the mirror 43, and the mask 44, and is then projected onto the work 3 by the projection lens 45. The pulse laser beam L is irradiated to the interface between the substrate 1 and the material layer 2 through the substrate 1 as shown in FIG. By irradiating the pulse laser beam L at the interface between the substrate 1 and the material layer 2, GaN near the interface between the material layer 2 and the substrate 1 is decomposed. In this way, the material layer 2 is peeled from the substrate 1.

FIG. 5 is a diagram showing the light intensity distribution of the laser beam irradiated to the workpiece 3 so as to overlap the regions S1 and S2 adjacent to each other of the workpiece 3 shown in FIG. 2, and aa ′ in FIG. It is line sectional drawing.
In the figure, the vertical axis indicates the intensity (energy value) of the laser beam irradiated to each irradiation area of the workpiece, and the horizontal axis indicates the conveyance direction of the workpiece. L1 and L2 indicate the profiles of the laser beams irradiated to the workpiece irradiation areas S1 and S2, respectively. The laser beams L1 and L2 are not irradiated at the same time, but the laser beam L2 is irradiated after one pulse interval from the irradiation of the laser beam L1.
In this example, as shown in FIG. 5, the cross sections of the laser beams L1 and L2 are formed in a substantially trapezoidal shape having a flat surface on the top (peak energy PE) following the edge portion LE that gently spreads in the circumferential direction. Yes. The laser beams L1 and L2 are superimposed in an energy region exceeding a decomposition threshold value VE necessary for decomposing and separating the material layer of the GaN-based compound from the sapphire substrate, as indicated by broken lines in FIG.

That is, in the light intensity distribution of each laser beam, the intensity (energy value) CE of the laser beam at the intersection position C between the laser beams L1 and L2 is set to a value exceeding the decomposition threshold value VE.
This is because, as described above, when the irradiation region is shifted from S1 to S2 after irradiating the irradiation region S1 of FIG. 2 with the laser beam, the temperature of the region S1 is already lowered to the room temperature level. This is because even if the irradiation region S2 is irradiated with the laser light in a state where the temperature of the region S1 is lowered to the room temperature level, the irradiation amount of the pulse laser light irradiated to each of the irradiation regions S1 and S2 is not integrated.
The intensity CE of the laser beam at the crossing position C between the laser beams L1 and L2, that is, the intensity of each pulsed laser beam in the region irradiated with the laser beam superimposed, becomes a value exceeding the decomposition threshold VE. By setting to, sufficient laser energy can be applied to peel the material layer from the substrate, and the material layer is surely peeled from the substrate without causing cracks in the material layer formed on the substrate. be able to.

(2) Second to Fourth Embodiments FIG. 8 is a diagram showing an outline of the configuration of a laser lift-off device according to second to fourth embodiments of the present invention described below.
In the laser lift-off device shown in FIG. 1, a work 3 in which a material layer 2 is formed on a substrate 1 that transmits laser light is placed on a work stage 31. The work stage 31 on which the work 3 is placed is placed on a transport mechanism 32 such as a conveyor, and is transported by the transport mechanism 32 at a predetermined speed. The workpiece 3 is irradiated with the laser beam L through the substrate 1 while being conveyed in a predetermined direction together with the workpiece stage 31.
The workpiece 3 is formed by forming a material layer 2 of a GaN (gallium nitride) compound on the surface of a substrate 1 made of sapphire. The substrate 1 may be any material as long as it can form a GaN-based compound material layer satisfactorily and transmits laser light having a wavelength necessary for decomposing the GaN-based compound material layer. A GaN-based compound is used for the material layer 2 in order to efficiently output high-output blue light or ultraviolet light with low input energy.

The laser beam should be appropriately selected according to the substrate 1 and the substance constituting the material layer peeled from the substrate 1. When the GaN-based compound material layer 2 is peeled from the sapphire substrate 1, for example, a KrF (krypton fluorine) excimer laser that emits a pulsed laser beam having a wavelength of 248 nm can be used. The light energy (5 eV) with a laser wavelength of 248 nm is between the band gap of GaN (3.4 eV) and the band gap of sapphire (9.9 eV). Therefore, a laser beam having a wavelength of 248 nm is desirable for peeling the material layer of the GaN compound from the sapphire substrate. A mask 44 for forming a predetermined laser beam pattern on the laser beam L emitted from the laser source is disposed above the workpiece 3. In FIG. 8, a projection lens described later is omitted.

FIG. 9 is a conceptual diagram of the optical system of the laser lift-off device of the second to fourth embodiments of the present invention.
In the figure, a laser lift-off device 10 includes a laser source 20 that generates pulsed laser light, a laser optical system 40 for shaping the laser light into a predetermined shape, a work stage 31 on which the work 3 is placed, A transport mechanism 32 that transports the work stage 31 and a controller 33 that controls the irradiation interval of the laser light generated by the laser source 20 and the operation of the transport mechanism 32 are provided.
The laser optical system 40 includes

cylindrical lenses

41 and 42, a mirror 43 that reflects the laser light in the direction of the workpiece, a mask 44 having an opening that transmits the laser light, and an image of the laser light L that has passed through the mask 44. 3 is provided with a projection lens 45 for projecting onto the projector 3. The mask 44 has a plurality of openings for dividing the laser beam, divides the laser beam emitted from the laser source 2 into a plurality of laser beams, and each of the divided laser beams causes each other to be placed on the workpiece. A plurality of spaced irradiation regions are formed. That is, the mask 44 functions as the laser beam forming means described above, and the plurality of openings serve as laser beam emitting portions.
The arrangement, shape, and area of the irradiation region of the pulse laser beam on the work 3 can be appropriately set by selecting the arrangement, shape, size, and the like of the opening of the mask 44 that functions as the laser beam forming unit. . A workpiece 3 is disposed at the tip of the laser optical system 40. The work 3 is placed on the work stage 31. The work stage 31 is placed on the transport mechanism 32 and is transported by the transport mechanism 32.

The pulsed laser light L generated by the laser source 20 passes through the

cylindrical lenses

41 and 42, the mirror 43, and the mask 44, and then is projected onto the work 3 by the projection lens 45. The pulse laser beam L is applied to the interface between the substrate 1 and the material layer 2 through the substrate 1. By irradiating the pulse laser beam L at the interface between the substrate 1 and the material layer 2, GaN near the interface between the material layer 2 and the substrate 1 is decomposed. In this way, the material layer 2 is peeled from the substrate 1.

(A) Second Embodiment FIG. 10 is a view showing a mask provided in a laser lift-off apparatus according to a second embodiment of the present invention. As shown in FIG. 10, the mask 44 of the present embodiment has a plurality of openings M1 to M5 as laser beam emitting portions spaced apart from each other in a metal plate portion, and as shown in FIG. It is drilled so as to be arranged on a straight line that is inclined with respect to the conveying direction of the workpiece 3 (arrow direction in the figure). As shown in FIG. 12 to be described later, the openings M1 to M5 serving as the respective laser light emitting portions emit from the adjacent laser light emitting portions (each opening of the mask) when the work 3 is conveyed in one direction. The light irradiation areas formed by the laser light are formed so as to be separated from each other without being continuous so that edge portions extending in a direction parallel to the conveyance direction of the workpiece 3 overlap.
The openings M1 to M5 formed in the mask 44 divide the laser beam emitted from the laser source to form a plurality of irradiation regions separated from each other. The area of each irradiation region is, for example, the shape of the irradiation region. When close to a square, the size is set to be 0.25 mm ² or less.
The shape of the openings M1 to M5 of the mask 44 is preferably a quadrangular shape having one side extending in a direction parallel to the moving direction of the workpiece 3, and particularly has two sides extending in a direction parallel to the moving direction of the workpiece 3. , Square and rectangular are preferable.

If the irradiation area by the divided laser light is reduced as described above, damage applied to the material layer when the material layer is peeled from the substrate can be reduced.
That is, as described above, when GaN is decomposed, shear stress is applied to the GaN layer, and cracks are generated at the boundary of the irradiation region of the laser light, which damages the edge of the irradiation region. The magnitude of the damage is considered to largely depend on the irradiation area of the laser beam.
As a result of verification through experiments and the like, when the shape of the irradiation region is close to a square as described above, if the irradiation area of the laser beam to the workpiece is 0.25 mm ² or less, cracks in the material layer of the workpiece It was confirmed that the occurrence of the occurrence can be prevented.

Hereinafter, a laser beam irradiation method according to the laser lift-off apparatus of this embodiment will be described.
11 to 14 are views showing a laser lift-off process of the second embodiment according to the laser lift-off apparatus of the present invention.
FIG. 11 is a diagram for explaining a laser beam irradiation method according to the laser lift-off apparatus of the present embodiment, where (a) shows a laser irradiation period, (b) shows a laser pause period, and (c) shows a laser irradiation period. The numbers in parentheses in the figure indicate the procedure of laser light irradiation, the steps (2) and (5) are executed during the laser light irradiation period (see FIG. 13), and the steps (3) and (4) are performed by the laser. It is executed during the light pause period (see FIG. 13).
FIG. 12 shows the scanning direction of the laser beam on the workpiece and the irradiation pattern of the laser beam on the workpiece, and FIG. 13 shows a time chart showing the timing of laser beam irradiation and pause. (2), (3), (4), and (5) in FIG. 13 correspond to the irradiation periods (2) and (5) and the rest periods (3) and (4) in FIG. Further, FIG. 14 shows the relationship between the irradiation timing of the pulse laser beam and the irradiation area on the workpiece.
In the laser lift-off apparatus of this embodiment, the mask is not moved, and the pulse laser beam is irradiated while moving the workpiece. However, for convenience of explanation, FIG. 12 is drawn to scan the laser beam. Yes.

In the procedure of (1) of FIG. 11A, the mask 44 is arranged so that the upper end of the uppermost opening M1 is aligned with the upper end of the workpiece 3 in the same line. The upper end of the opening M1 may extend from the upper end of the workpiece 3. In the procedure (2), the workpiece 3 is conveyed in one direction from the right to the left while irradiating the laser beam.
Here, as shown in FIGS. 12A and 12B, the laser light passes through the mask 44 shown in FIG. 10 so that the irradiation areas LA to LE formed by the divided laser light become the workpiece 3. Are arranged on a straight line inclined with respect to the conveying direction. The laser light is directed from the left side to the right side of the work 3 on the work 3 from the upper end of the uppermost opening M1 (virtual line LL1) of the mask 44 to the lower end of the lowermost opening M5 of the mask 44 ( The region S1 over the virtual line LL2) is irradiated.

The irradiation areas LA and LB, LB and LC, LC and LD, and LD and LE formed on the workpiece 3 by the laser beam irradiated from the opening of the mask 44 are transferred to the workpiece 3 when the workpiece 3 is conveyed in one direction. The edge portions LA1 and LB1 ′ extending in the direction parallel to the moving direction are overlapped with each other (the same applies to LB, LC, LD,...), And the overlapping region T1 is formed. Further, when the work 3 is transported in one direction, the transport speed of the work 3 and the laser so that the edge portions LA2, LB2,... Extending in the direction orthogonal to the transport direction of the work 3 in each irradiation region overlap each other. The pulse interval of light is set.

Here, as shown in FIG. 12B, the irradiation areas LA and LB, LB and LC, LC and LD, and LD and LE formed by the laser light irradiated from the openings of the adjacent masks 44 are respectively workpieces. When 3 is conveyed in one direction, edge portions LA1 and LB1 ′ extending in a direction parallel to the moving direction of the workpiece 3 are superimposed on each other (the same applies to LB, LC, LD,...), And an overlapping region T1 is formed. Irradiated as follows.
Further, when the work 3 is transported in one direction, the work speed of the work 3 and the pulse laser beam are such that the edge portions LA2, LB2,... Extending in the direction orthogonal to the moving direction of the work 3 in each irradiation region overlap each other. The irradiation interval is set. The pulse interval of the laser beam is set to be shorter than the time required for the work to move a distance corresponding to the irradiation region for one shot of the laser beam. For example, when the conveying speed of the workpiece 3 is 100 mm / second and the width of the laser light overlapping region ST is 0.1 mm, the pulse interval of the laser light is 0.004 seconds (250 Hz).
Further, as shown in FIGS. 11 and 12, laser light is irradiated in order from one end side of the work 3 toward the other end, so that it is peeled off sequentially from the substrate as shown by the dotted line in FIG. In the peeled region of the material layer, the sides that are peeled off from the substrate for the first time are always two sides.

FIG. 14 is a diagram showing the relationship between the irradiation timing of the pulse laser beam and the irradiation region on the workpiece, wherein FIG. 14 (a) shows the irradiation region on the workpiece, (b) shows each pulse laser beam, In the figure, laser light is irradiated in the order of irradiation areas A → B → C on the workpiece, the irradiation area A is irradiated with laser light a, the irradiation area B is irradiated with laser light b, and the irradiation area C is irradiated. Indicates a case where the laser beam c is irradiated.
In FIG. 14, the pulse laser beam a passes through the opening of the mask 44 and irradiates the irradiation area A on the workpiece 3 until the next pulse laser beam b is irradiated. It moves to the position where the laser beam is irradiated to the irradiation region.
Then, the next pulse laser beam b is applied at a timing such that an edge portion (a hatched portion in the figure) T3 extending in a direction orthogonal to the conveyance direction of the workpiece 3 in the irradiation region A and the irradiation region B overlaps. 3 is irradiated to the irradiation region B on the upper side.
Similarly, before the next pulse laser beam c is irradiated, the workpiece 3 moves to a position where the irradiation region C in the figure is irradiated with the laser beam, and the next pulse laser beam c is applied to the irradiation region B. Irradiation is performed at such a timing that the edge portions of the irradiation region C (hatched portions in the figure) overlap each other.

In the rest period of the pulse laser light of (3) and (4) in FIG. 11, the work 3 is transported in the direction of the arrow (3) shown in FIG. 11 in order to irradiate the next region of the work with laser light. The transport distance at this time is set so that the laser light irradiation areas S1 and S2 overlap each other. Further, in the procedure (4), in order to make the moving direction of the work 3 with respect to the mask 44 the same as the moving direction of (2), the work 3 is conveyed from the left to the right according to the arrow (4) in FIG.
In the next procedure (5), the workpiece 3 is conveyed in one direction from the right to the left while irradiating the laser beam. In the procedure of (5), in the same manner as the procedure of (1), the lowermost opening of the mask 44 from the upper end of the uppermost opening M1 of the mask 44 (virtual line LL3 in FIG. 11C) in the work 3. It irradiates to area | region S2 covering the lower end (virtual line LL4 of FIG.11 (c)) of M5. Irradiation regions LF and LG, LG and LH, LH and LI, and LI and LJ formed by laser light emitted from openings adjacent to the mask 44 are overlapped with edge portions extending in a direction parallel to the moving direction of the workpiece 3. Irradiate as you do. Also, the laser light is irradiated so that the irradiation regions LF to LJ overlap with the edge portions of the irradiation regions extending in the direction orthogonal to the conveyance direction of the workpiece 3 as described above.

In the above embodiment, the mask 44 having a plurality of openings M1-M5 (corresponding to the laser beam emitting portions) arranged apart from each other is provided as the laser beam forming means, and the openings M1-M5 of the mask 44 are provided. The irradiation regions LA-LE that are separated from each other are formed on the workpiece by the laser beam divided by the above, and the irradiation region LA-LE formed by the laser beams emitted from the adjacent openings M1-M5 Edge portions extending in a direction parallel to the moving direction are configured to be collectively irradiated onto the workpiece while being sequentially superimposed as the workpiece is moved in one direction. For this reason, laser lift-off can be performed in a short time, and throughput can be improved.
In addition, in the above-described embodiment, the irradiation areas LA to LE formed by the laser beams emitted from the laser beam emitting portions arranged apart from each other are sequentially superimposed at intervals as described above.
For this reason, the irradiation energy of each divided | segmented laser beam is not added together. For example, the irradiation area LA formed by laser light is formed after LB, but since the time until the material layer returns from the decomposition temperature to room temperature is extremely short, it is already irradiated by LB when LA is irradiated. Since the region T1 is already at room temperature, the irradiation energy of the irradiation regions LA and LB formed by the laser light is not added. That is, each laser beam divided by the mask 44 is the same as being individually irradiated onto the workpiece, and each laser irradiation region has a small area. For this reason, damage to the material layer when the material layer is peeled from the substrate can be reduced.
Furthermore, in this embodiment, as shown in FIGS. 11 and 12, the irradiation region groups S1, S2,... Are sequentially arranged from the one end side of the work 3 toward the other end in order. The laser beam is irradiated over the entire surface of the work 3. By irradiating with laser light in this way, in the peeling region of the material layer sequentially peeled from the substrate, the sides to be peeled from the substrate for the first time are always two sides.

As described above, the laser lift-off process of the second embodiment irradiates the workpiece 3 with the laser beam through the mask 44 having a plurality of openings. Thus, the laser lift-off process can be performed in a short time while the damage can be reduced.
Further, in the laser lift-off process of the second embodiment, since the side to be peeled off from the substrate is always two sides for the first time in the peeling region of the material layer sequentially peeled from the substrate, the material layer is decomposed as described above. The material layer after peeling from the substrate can be well harmonized by ensuring the escape path of the gas generated from time to time and the length of the side where the stress generated in the initial stage when the material layer is decomposed is sufficiently long. The occurrence of cracks in can be prevented or suppressed.

(B) Modification of the second embodiment In the above embodiment, the divided laser beam is formed using a mask. However, as will be described below, the divided laser beam is divided using an optical fiber. It may be formed.
FIGS. 15 and 16 are diagrams showing modifications of the second embodiment. FIG. 15 is a conceptual diagram of an optical system of a laser lift-off device when other laser beam forming means is used, and FIG. 15 is an enlarged view of the laser beam forming means shown in FIG. 15, FIG. 16 (a) is an enlarged view of the vicinity of the workpiece, and FIG. 16 (b) is a view showing the arrangement of the light emitting elements. .
In this modification, the laser beam forming means is composed of light guides 61a to 61e, light emitting elements 62a to 62e, and optical fibers 60a to 60e, and the laser beam emitting part corresponding to the opening of the mask is the light emitting elements 62a to 62e. Corresponds to 62e.
That is, as shown in FIGS. 16 (a) and 16 (b), the plurality of light emitting elements 62a-62e are straightly inclined with respect to the conveying direction of the workpiece 3 like the openings M1 to M5 of the mask shown in FIG. For example, as shown in FIG. 12, each of the light emitting elements 62a to 62e is arranged on a line. When the workpiece 3 is conveyed in one direction, each of the light emitting elements 62a to 62e Are arranged so as to be separated from each other so that the edge portions extending in the direction parallel to the conveyance direction of the workpiece 3 overlap in the irradiation region formed by the above.
Even if an optical fiber is used as in this modification, the same effect as in the second embodiment can be obtained by irradiating the workpiece 3 with laser light as described in the second embodiment. Laser lift-off processing can be performed for a short time, damage can be reduced, and generation of cracks in the material layer after peeling from the substrate can be prevented or suppressed.

(C) Third Embodiment FIGS. 17 to 21 are diagrams for explaining a laser lift-off process according to a third embodiment of the laser lift-off apparatus of the present invention. As shown in FIG. 17, the mask 44 has a plurality of openings M1 to M9 as laser beam emitting portions spaced apart from each other and inclined with respect to the conveying direction of the workpiece 3 in the metal plate portion. It is drilled in an X shape by arranging it on one imaginary line L1 and the other imaginary line L2 intersecting each other at the opening M3 located at the same position.
As shown in FIG. 20, each of the openings M1 to M9 extends in a direction parallel to the conveying direction of the workpiece 3 of the laser beam emitted from each adjacent laser beam emitting portion when the workpiece 3 is conveyed in one direction. The edges are formed so as not to be continuous with each other so as to overlap each other.
FIG. 18 shows the operation of the mask shutters MS1 to MS4 for opening and closing the openings M1 to M9 provided in the mask 44. The mask 44 of the third embodiment can form two different mask patterns by appropriately opening and closing the mask shutter.
FIG. 4A shows a state in which all the mask shutters MS1-MS4 are opened, but in this embodiment, the mask 44 is not used in this state. As shown in FIGS. 2B and 2C, the mask 44 of the present embodiment is masked so that the openings M1 to M9 are aligned on either one of the virtual lines L1 or L2. By opening and closing the shutters MS1-MS4, both the mask pattern MP1 and the mask pattern MP2 can be formed. The mask pattern MP1 and the mask pattern MP2 are used by switching each time the workpiece moving direction with respect to the laser beam is switched.

A laser beam irradiation method according to the laser lift-off apparatus of the present invention will be described with reference to FIG. The numbers in parentheses in the figure indicate the laser light irradiation procedure. In this laser beam irradiation method, as described above, the workpiece is moved without moving the mask 44 and the laser beam is irradiated. FIG. 20 shows the irradiation pattern of the laser beam on the workpiece. For convenience of explanation, FIG. 20 shows the laser beam being scanned. FIG. 21 is a time chart showing a pulse laser beam irradiation period and a pause period.
In the procedure (1) shown in FIG. 19, the mask 44 is arranged so that the upper end of the uppermost opening M 1 in the drawing is aligned with the upper end of the workpiece 3. The upper end of M1 may extend from the upper end of the workpiece 3. At this time, in FIG. 18B, the mask shutters MS2, MS3 are retracted from the mask so as to open the openings M1-M5 arranged on the virtual line L1, and are arranged on the virtual line L2. The mask shutters MS1, MS4 are advanced so as to close the openings M6-M9. In this way, a mask pattern MP1 is formed in the mask 44.

In the procedure (2) shown in FIG. 19, the workpiece 3 is conveyed in one direction from right to left while irradiating laser light. At this time, since the laser light passes through the mask pattern MP1, as shown in FIGS. 20A and 20B, the irradiation areas LA to LE formed by the laser light are inclined straight with respect to the conveyance direction of the workpiece 3. Irradiation patterns P1 arranged in an array on the line are formed. The irradiation pattern P 1 moves from the upper end of the opening M 1 located on the uppermost side of the mask 44 in the work 3 (virtual line LL 1 in FIG. 19A) as the work 3 moves from right to left. The region S1 is irradiated over the lower end (the virtual line LL2 in FIG. 19A) of the opening M5 located at the lowest position of the mask 44.
As shown in FIG. 20 (b), the irradiation areas LA and LB, LB and LC, LC and LD, and LD and LE formed by the laser beams irradiated from the adjacent laser beam emitting portions are combined with each other. When moved in the direction, an edge portion extending in a direction parallel to the moving direction of the workpiece 3 is superimposed. In addition, the irradiation areas LA to LE formed by the laser light are irradiated so that the respective edge portions extending in the direction orthogonal to the moving direction of the workpiece 3 overlap as described with reference to FIG.

Next, the procedure (3) shown in FIG. 19 is executed during the pause period of the pulse laser beam (see FIG. 21), and preparation for irradiating the next region of the workpiece 3 with the laser beam, that is, the movement of the workpiece. Change the mask pattern.
In the procedure of (3), in order to irradiate the next area of the work 3 with the laser beam, the work 3 is moved to a position slightly shorter than the laser-irradiated area S1 in FIG. It is moved in the direction of the arrow (3) shown. The reason why the conveyance distance of the workpiece 3 is slightly shorter than the area S1 is to overlap the areas S1 and S2 shown in FIG.
Further, in the procedure (3), the mask pattern MP1 is changed to the mask pattern MP2.
To change the mask pattern, as shown in FIG. 18 (c), the mask shutters MS2 and MS3 are advanced to close the openings M1-M5 except for the opening M3 arranged on the virtual line L1, and the mask pattern is changed to the virtual line L2. The mask shutters MS1 and MS4 are retracted out of the mask 44 in order to open the openings M6 to M9 arranged in the above. In this way, the mask pattern MP2 is formed in the mask 44.

In the procedure (4) shown in FIG. 19, the workpiece 3 is moved from the left to the right according to the arrow (4) in FIG. 19 (b) while irradiating the laser beam. At this time, as shown in FIG. 20C, an irradiation pattern P2 is formed in which irradiation regions LF to LJ formed by laser light are arranged on a straight line inclined with respect to the moving direction of the workpiece 3. The irradiation pattern P 2 has a line-symmetric shape of the irradiation pattern P 1 with the scanning direction of the laser beam with respect to the workpiece 3 as the center. The laser beam having the irradiation pattern P2 is directed from the right side to the left side of the workpiece 3 shown in FIG. 20A, that is, from the opposite direction to when the laser beam is irradiated onto the region S1 irradiated with the laser beam. Irradiated and from the upper end of the opening M9 positioned above the mask 44 in the workpiece 3 (virtual line LL3 in FIG. 19B) to the lower end of the opening positioned at the lowermost end of the mask 44 (virtual line in FIG. 19B) The region S2 over the line LL4) is irradiated.

As shown in FIG. 20 (c), the laser light irradiation areas LF and LG, LG and LH, LH and LI, and LI and LJ irradiated from the adjacent openings respectively are the workpieces when the workpiece 3 is conveyed in one direction. The edge portions extending in the direction parallel to the conveyance direction 3 overlap. In the procedure of (3) of FIG. 19, the areas S1 and S2 are overlapped by adjusting the transport distance of the workpiece 3 as described above. Further, the irradiation regions LF to LJ formed by the laser light are irradiated so that the edge portions extending in the direction orthogonal to the moving direction of the workpiece overlap. The steps (1) to (4) are sequentially performed from one end of the work 3 so that the irradiation region groups S1, S2,... Are sequentially formed from one end to the other end of the work 3. By repeatedly executing the laser beam, the entire surface of the workpiece 3 is irradiated with the laser beam.

According to the laser lift-off process of the third embodiment, the edge portion of the laser light emitted from the openings M1 to M9 as the adjacent laser light emitting portions extending in the direction parallel to the moving direction of the workpiece makes the workpiece in one direction. Since light emitted from a plurality of laser light emitting portions is collectively irradiated onto the workpiece while being sequentially superimposed as it moves, basically the laser light to the workpiece is substantially the same as in the second embodiment. Since the irradiation area can be made large, a laser lift-off process can be performed in a short time. Further, as in the second embodiment, in the peeling region of the material layer sequentially peeled from the substrate, the side to be peeled from the substrate for the first time is always two sides as shown by the dotted lines in FIGS. become. For this reason, as described above, the harmony between ensuring the escape path of the gas generated during the decomposition of the material layer and that the total length of the side on which the stress generated at the initial stage during the decomposition of the material layer is sufficiently long is excellent. The generation of cracks in the material layer after peeling from the substrate can be prevented or suppressed.
Further, since the laser light irradiation patterns P1 and P2 formed by the mask 44 have a line-symmetric shape with respect to the scanning direction of the laser light with respect to the work 3, respectively, the work transport operation is simplified. be able to. This will be described below.

According to the laser lift-off process of the third embodiment, the scan direction of the laser beam with respect to the workpiece 3 is changed by 180 ° in the regions S1 and S2 of the workpiece 3 as shown in FIG. Even in this case, the laser light irradiation patterns P1 and P2 are arranged on two straight lines that are in a line-symmetrical relationship with respect to the moving direction of the workpiece. As shown, the number of sides of the material layer that is peeled off from the substrate for the first time by laser light irradiation can always be two.
In other words, in this embodiment, the scanning direction of the workpiece 3 can be alternately changed by 180 ° on the left and right (the moving direction of the workpiece is only one direction in the method of the second embodiment), so the laser shown in FIG. The procedure (4) shown in the light irradiation method, that is, the procedure for making the moving direction of the workpiece constant can be omitted. Therefore, the workpiece transfer operation can be simplified.
In the above embodiment, the divided laser beam is formed using a mask. However, as shown in FIGS. 15 and 16, the divided laser beam may be formed using an optical fiber. Good. When an optical fiber is used, it is not necessary to use a mask shutter as shown in this embodiment, and light emission from the optical fiber may be turned on and off.

(C) Fourth Embodiment FIGS. 22 to 25 show a laser lift-off process according to a fourth embodiment of the laser lift-off apparatus of the present invention. As shown in FIG. 22, the mask 44 separates a plurality of openings M1-M9 as laser beam emitting portions from each other in the metal plate portion and is inclined with respect to the conveying direction of the workpiece 3 and V It is drilled so as to be arranged in a straight line on one imaginary line L1 and the other imaginary line L2 intersecting in a letter shape.
As described above, each of the openings serving as the laser beam emitting portions has an edge portion extending in a direction parallel to the conveying direction of the workpiece 3 of the laser beam emitted from the adjacent opening when the workpiece 3 is conveyed in one direction. They are formed apart from each other so as to overlap.

FIG. 24 shows a mask transport mechanism 50 for moving the mask 44 left and right on the paper surface. In the mask 44 according to the fourth embodiment, the mask pattern is changed by sliding on the mask stage 51 in the horizontal direction on the paper surface in accordance with the conveying direction of the workpiece. The mask 44 can form two mask patterns with the opening M5 located at the intersection of one virtual line L1 and the other virtual line L2 as a boundary. As shown in FIG. 22, the mask 44 has openings M1-M5 arranged in a straight line on one imaginary line L1 within the laser light irradiation range, and openings arranged in a straight line on the other imaginary line L2. The mask pattern MP1 is formed by retracting M6 to M9 out of the laser light irradiation range. On the contrary, the mask 44 retracts the openings M1-M4 arranged in a straight line on one imaginary line L1 out of the laser light irradiation range, and opens the openings M5 arranged in a straight line on the other imaginary line L2. The mask pattern MP22 is formed by arranging -M9 in the laser beam irradiation range.

The laser lift-off process of the fourth embodiment will be described with reference to FIG. The numbers in parentheses in the figure indicate the laser light irradiation procedure. This laser beam irradiation method is different from the second and third embodiments in that the mask pattern is changed by moving the mask 44 according to the conveyance of the workpiece. In the laser lift-off process of the fourth embodiment, the irradiation pattern of the laser beam to the workpiece is the same as that of the third embodiment. Therefore, the irradiation pattern of the laser beam to the workpiece will be described with reference to FIG. .
In the procedure (1) shown in FIG. 23, the mask 44 is arranged so that the upper end of the uppermost opening M 5 in FIG. 23 is aligned with the same virtual line LL 1 as the upper end of the work 3. The upper end of the opening M5 may extend from the upper end of the workpiece 3. At this time, the mask 44 is transported by the mask transport mechanism, and the openings M1 to M5 are disposed within the laser light irradiation range and the openings M6 to M9 are retracted outside the laser light irradiation range as shown in FIG. The mask pattern MP1 is formed on the mask 44.

In the procedure (2) shown in FIG. 23, the workpiece 3 is conveyed in one direction from the right to the left while irradiating the laser beam. At this time, since the laser light passes through the mask pattern MP1 of the mask 44, as shown in FIG. 20B, the irradiation areas LA to LE formed by the laser light are straightly inclined with respect to the workpiece conveyance direction. Irradiation patterns P1 arranged in an array on the line are formed.
When the workpiece 3 moves from the right side to the left side, the laser light is moved from the right side to the left side, as shown in FIG. 23A, the upper end of the opening M5 positioned above the mask 44 in the workpiece 3 (FIG. 23A). ) From the imaginary line LL1) to the lower end of the opening M1 located on the lowermost side of the mask 44 (the imaginary line LL2 in FIG. 23A).

Next, the procedure (3) shown in FIG. 23 is executed during the pause period of the pulse laser beam (see FIG. 25), and preparation for irradiating the next region of the workpiece 3 with the laser beam, that is, the movement of the workpiece. Change the mask pattern.
In the procedure of (3), in order to irradiate the next region of the workpiece with the laser beam, the workpiece 3 is slightly shorter than the region S1 irradiated with the laser beam of FIG. Is moved in the direction of arrow (3) shown in FIG. The reason why the transport distance of the workpiece 3 is slightly shorter than the laser irradiation area S1 is to overlap the laser light irradiation areas S1 and S2 shown in FIG.
Further, in the procedure (3), the mask pattern MP1 is changed to the mask pattern MP2. To change the mask pattern, the mask 44 is slid by using the mask transport mechanism shown in FIG. 24, and the openings M1-M4 arranged on the virtual line L1 are retracted outside the laser light irradiation range, and the mask pattern is moved onto the virtual line L2. The arranged openings M5-M9 are arranged within the laser beam irradiation range. In this way, a mask pattern MP2 is formed in the mask 44.

In the procedure (4) shown in FIG. 23, the workpiece 3 is moved from the left to the right according to the arrow (4) in FIG. At this time, as shown in FIG. 20C, an irradiation pattern P2 in which irradiation regions LF to LJ formed by laser light are arranged in an array on a straight line inclined with respect to the moving direction of the work 3 is formed. Is done. The irradiation pattern P 2 has a line-symmetric shape of the irradiation pattern P 1 with the scanning direction of the laser beam with respect to the workpiece 3 as the center.
As shown in FIG. 23 (b), the laser beam having the irradiation pattern P2 is irradiated from the right side to the left side of the workpiece 3, that is, from the opposite direction to when the region S1 is irradiated with the laser beam. In the workpiece 3, from the upper end of the opening M5 positioned above the mask 44 (virtual line LL3 in FIG. 23B) to the lower end of the opening M9 positioned at the lowermost end of the mask 44 (virtual line LL4 in FIG. 23B). ) Over the region S2. Such procedures (1) to (4) are sequentially repeated in order from one end of the work to the other end of the work so that the irradiation region groups S1, S2,. Thus, the laser beam is irradiated over the entire surface of the work 3.

According to the laser lift-off process of the fourth embodiment described above, basically the same effect as the laser lift-off process of the second embodiment can be expected. Further, since the laser light irradiation patterns P1 and P2 formed by the mask 44 have a line-symmetric shape with respect to the scanning direction of the laser light with respect to the workpiece, they are peeled off from the substrate for the first time by laser light irradiation. The number of sides of the material layer is always two, and the workpiece transfer operation can be simplified as in the third embodiment.
In the second to fourth embodiments, the divided laser beam is formed using a mask. However, as shown in FIGS. 15 and 16, the laser beam divided using an optical fiber is used. Light may be formed. When an optical fiber is used, it is not necessary to move the mask as shown in this embodiment, and light emission from the optical fiber may be turned on and off.

(3) Method for Manufacturing Semiconductor Light-Emitting Element Using Laser Lift-Off Device Finally, a method for manufacturing a semiconductor light-emitting element that can use the above-described laser lift-off device will be described. Below, the manufacturing method of the semiconductor light-emitting device formed of a GaN-based compound material layer will be described with reference to FIG.
As the substrate for crystal growth, a sapphire substrate capable of crystal growth of a gallium nitride (GaN) compound semiconductor that transmits laser light and forms a material layer is used. As shown in FIG. 26A, a GaN layer 102 made of a GaN-based compound semiconductor is rapidly formed on the sapphire substrate 101 by using, for example, a metal organic chemical vapor deposition method (MOCVD method).
Subsequently, as illustrated in FIG. 26B, an n-type semiconductor layer 103 and a p-type semiconductor layer 104 that are light emitting layers are stacked on the surface of the GaN layer 102. For example, GaN doped with silicon is used as the n-type semiconductor, and GaN doped with magnesium is used as the p-type semiconductor.
Subsequently, as shown in FIG. 26C, solder 105 is applied on the p-type semiconductor layer 104. Subsequently, as shown in FIG. 26D, a support substrate 106 is attached on the solder 105. The support substrate 106 is made of, for example, an alloy of copper and tungsten.
Then, as shown in FIG. 26E, laser light 107 is irradiated from the back surface side of the sapphire substrate 101 toward the interface between the sapphire substrate 101 and the GaN layer 102. The laser beam 107 is shaped so that the irradiation area is a square having an area of 0.25 mm ² or less, and the light intensity distribution is substantially trapezoidal as shown in FIG.
By irradiating the interface between the sapphire substrate 101 and the GaN layer 102 with the laser beam 107 and decomposing the GaN layer 102, the GaN layer 102 is peeled from the sapphire substrate 101. ITO 108 which is a transparent electrode is formed on the surface of the GaN layer 102 after peeling by vapor deposition, and the electrode 109 is attached to the surface of the ITO 108.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Material layer 3 Workpiece 10 Laser lift-off device 20 Laser source 31 Workstage 32 Transport mechanism 33 Control unit 40 Laser

optical system

41, 42 Cylindrical lens 43 Mirror 44 Mask 45 Projection lens 50 Mask transport mechanism 51 Mask stages 60a-60e Fiber 61a to 61e Light guides 62a to 62e Light emitting element 101 Sapphire substrate 102 GaN layer 103 n-type semiconductor layer 104 p-type semiconductor layer 105 solder 106 support substrate 107 laser beam 108 transparent electrode (ITO)
109 Electrode L Laser light M1 to M9 Mask openings MS1 to MS4 Mask shutter

Claims

A laser that irradiates a workpiece in which a material layer is formed on a substrate with a laser beam from a laser source through the substrate, decomposes the material layer at an interface between the substrate and the material layer, and peels the workpiece from the substrate In the lift-off method,
The laser beam is irradiated onto the workpiece while changing the irradiation region on the workpiece, and the edge portion of the irradiation region is sequentially superimposed as the workpiece moves in one direction relative to the laser source. And
The irradiation region of the laser beam on the workpiece is formed in a quadrangular shape having one side extending in a direction parallel to the moving direction of the workpiece,
The laser beam is applied to the workpiece so that the material layer that is peeled off from the substrate for the first time is separated into two sides in the rectangular peeling region of the material layer that is peeled off sequentially from the substrate. And a laser lift-off method.
With the laser beam, each irradiation region group is formed so as to be sequentially arranged from one end to the other end of the workpiece, and the irradiation region group formed first and the last irradiation region group formed in the workpiece are the workpiece The laser lift-off method according to claim 1, wherein the laser lift-off method is formed so as to extend from one edge portion and the other edge portion.
The laser beam emitted from the laser source is divided into a plurality of laser beams, and a plurality of irradiation regions separated from each other are formed on the workpiece by the divided pulse laser beams,
The plurality of irradiation areas are sequentially overlapped with the ends of the adjacent irradiation areas extending in a direction parallel to the movement direction of the work as the work moves in one direction relative to the laser source. The laser lift-off method according to claim 1, wherein the laser lift-off method is arranged as follows.
In a laser lift-off device for irradiating a workpiece having a material layer formed on a substrate with laser light through the substrate and peeling the material layer from the substrate at an interface between the substrate and the material layer,
A laser source that generates laser light in a wavelength region that passes through the substrate;
A transport mechanism for relatively transporting the workpiece and the laser source;
The laser beam is irradiated to the workpiece so that each irradiation region is sequentially arranged from one end to the other end of the workpiece while changing the irradiation region to the workpiece, and an edge portion of the irradiation region is the edge portion of the irradiation region. A control unit that controls an irradiation interval of the laser light and a conveyance operation of the workpiece by the conveyance mechanism so that the workpiece is sequentially superimposed as the workpiece moves in one direction relative to the laser source;
A laser optical system configured to irradiate the workpiece with a laser beam emitted from the laser source, shaped into a square shape having one side extending in a direction parallel to the moving direction of the workpiece,
The control unit irradiates the workpiece with laser light so that an irradiation region group formed first and an irradiation region group formed last in the workpiece extend from one edge portion and the other edge portion of the workpiece. At the same time, the workpiece is irradiated with the laser light so that the material layer to be peeled for the first time from the substrate has two sides of the square peeled region of the material layer that has been sequentially peeled from the substrate. A laser lift-off device.
Laser light emitted from the laser source is divided into a plurality of laser lights, and laser light forming means for forming a plurality of irradiation regions separated from each other on the workpiece by the divided pulse laser lights,
In the plurality of irradiation areas formed by the laser beam forming means, the ends of the adjacent irradiation areas extending in a direction parallel to the movement direction of the workpiece move relative to the laser source in one direction. The laser lift-off device according to claim 4, wherein the laser lift-off devices are arranged so as to be sequentially overlapped with each other.
6. The laser lift-off apparatus according to claim 5, wherein the laser beam forming means is a mask having a plurality of rectangular openings.
The laser lift-off device according to claim 5 or 6, wherein the irradiation area formed on the workpiece is arranged on a straight line inclined in the moving direction of the workpiece.
The mask is composed of one mask pattern and the other mask pattern arranged in a straight line on one virtual line and the other virtual line where the plurality of openings intersect with each other, and the opening of the mask is X The laser lift-off device according to claim 6, wherein the laser lift-off device is arranged in a letter shape.
A mask shutter for opening and closing the plurality of openings of the mask;
In the mask shutter, only the opening of the one mask pattern is opened at the time of transferring the workpiece, and the other mask pattern except for the opening located at the intersection of the one virtual line and the other virtual line. Open and close so that the opening of
Each time the mask shutter is switched by 180 °, the one mask pattern and the other mask pattern except for the opening located at the intersection of the one virtual line and the other virtual line. The laser lift-off device according to claim 8, wherein each open / close state is switched.
The mask is composed of one mask pattern composed of a plurality of openings arranged on one imaginary line and the other mask pattern composed of a plurality of openings arranged on the other imaginary line. The laser lift-off device according to claim 6, wherein the laser lift-off device is arranged in a letter shape.
The mask includes a mask transport mechanism that transports the mask so that only one of the one mask pattern and the other mask pattern is disposed in the laser light irradiation region,
11. The laser lift-off device according to claim 10, wherein the mask transport mechanism switches a mask pattern arranged in the laser light irradiation region every time the work transport direction is switched by 180 °.