Laser light irradiation device and laser light irradiation method

Abstract

The present invention provides a laser beam irradiation device and a laser beam irradiation method that allow for flexible changes in the irradiation range of the laser beam. [Solution] A laser beam irradiation device comprising: an optical system for shaping laser light emitted from a light source into a longitudinal shape extending in a first direction; a light-shielding section including a first light-shielding plate that is movable in the first direction and shields the laser light from one or both sides in the first direction; a photomask provided downstream of the light-shielding section for shaping the laser light into a plurality of laser spots aligned in the first direction; and a stage on which an object to be irradiated by the plurality of laser spots is placed and which moves in a second direction perpendicular to the first direction.

Description

Technical Field

[0006] , , ,

[0001] The present invention relates to a laser light irradiation device and a laser light irradiation method.

Background Art

[0002] In recent years, various laser light irradiation devices for processing an object by irradiating the object with laser light have been developed. For example, Patent Documents 1 and 2 below disclose a laser light irradiation device that performs laser lift-off to peel a crystal layer formed on a substrate from the substrate by irradiating the back surface of the substrate with laser light.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

[0007] Furthermore, in order to solve the above problems, according to another aspect of the present invention, a laser beam irradiation method is provided, which includes the steps of: shaping a laser beam emitted from a light source into a longitudinal shape extending in a first direction; shielding the laser beam from one or both sides in the first direction with a first light-shielding plate that is movable in the first direction; shaping the laser beam into a plurality of laser spots aligned in the first direction with a photomask provided downstream of the first light-shielding plate; and irradiating an object placed on a stage that moves in a second direction perpendicular to the first direction with the plurality of laser spots. [Effects of the Invention]

[0008] As described above, according to the present invention, it is possible to flexibly change the irradiation range of the laser light. [Brief explanation of the drawing]

[0009] [Figure 1] This is an explanatory diagram showing the configuration of a laser light irradiation device according to one embodiment of the present invention. [Figure 2] This is an explanatory diagram showing how laser light emitted from a light source is shaped into a laser spot. [Figure 3] This is an explanatory diagram showing the relationship between the irradiation area, illuminated by multiple laser spots, and the target object in the XY plane. [Figure 4] This is an explanatory diagram showing the configuration of a modified laser light irradiation device. [Figure 5]This is an explanatory diagram showing the relationship between the irradiation area and the object, where multiple laser spots are irradiated, in the modified example, on the XY plane. [Modes for carrying out the invention]

[0010] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. In this specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant descriptions will be omitted.

[0011] <1. Laser light irradiation device> First, with reference to Figure 1, the configuration of a laser light irradiation device according to one embodiment of the present invention will be described. Figure 1 is an explanatory diagram showing the configuration of the laser light irradiation device 1 according to this embodiment.

[0012] As shown in Figure 1, the laser light irradiation device 1 comprises an optical system 10, a light shielding unit 21, a photomask 22, a light focusing member 23, a stage 31, and a control device 40. The laser light irradiation device 1 is a processing device that processes an object 30 placed on the stage 31 by irradiating the object 30 with a laser spot LS.

[0013] For example, the laser light irradiation device 1 may be a laser lift-off device that performs laser lift-off (LLO) on a semiconductor chip Cp provided on an object 30. In such a case, the object 30 is a laminate of a transfer substrate, a semiconductor chip Cp such as an LED (Light-Emitting Diode), and a sapphire substrate. The semiconductor chip Cp is arranged in a matrix, for example, in a first direction and a second direction orthogonal to the first direction. The laser light irradiation device 1 can separate the semiconductor chip Cp from the sapphire substrate by heating and decomposing the interface between the semiconductor chip Cp and the sapphire substrate with a laser spot LS.

[0014] The optical system 10 includes a light source 11, an attenuator 12, a beam expander 13, a homogenizer 14, a condenser lens group 15, and a reflective mirror 16. The optical system 10 equalizes the energy distribution of the laser light L emitted from the light source 11 and shapes it into a longitudinal shape extending in a first direction before outputting it to the subsequent light shielding section 21 and photomask 22. For example, the optical system 10 may output a line-shaped laser light L extending in a first direction to the subsequent light shielding section 21 and photomask 22.

[0015] The light source 11 has an oscillator, an amplifier, and a wavelength converter, and emits pulsed high-density excimer laser light. The light source 11 may emit, for example, a high-density UV (Ultra Violet) laser light pulse with a wavelength of 248 nm. The attenuator 12 is composed of a combination of a polarization rotor and a polarizer. The attenuator 12 can attenuate the amount of laser light L emitted from the attenuator 12 to an appropriate amount by controlling the polarization of the incident laser light L.

[0016] The beam expander 13 is composed of a combination of a convex lens and a concave lens. The beam expander 13 can expand the beam diameter of the laser light L by first focusing the incident laser light L to a focal point with the convex lens, then diverging it with the concave lens, and finally collimating it with the convex lens. The homogenizer 14 is composed of a fly-eye lens in which multiple lens alignments are arranged in a matrix in a plane perpendicular to the optical axis. The homogenizer 14 can homogenize the energy distribution in the cross-section of the expanded laser light L.

[0017] The condenser lens group 15 is composed of a plurality of cylindrical lenses. The condenser lens group 15 can condense the laser beam L with a uniform energy distribution and can shape the shape of the laser beam L into a longitudinal shape extending in the first direction. The reflection mirror 16 reflects the laser beam L shaped into a longitudinal shape extending in the first direction, and emits the laser beam L to the subsequent light shielding part 21 and the photomask 22. For example, the reflection mirror 16 may be a multilayer film mirror that reflects the laser beam L so that the laser beam L is incident on the main surface of the photomask 22 substantially perpendicularly.

[0018] The light shielding part 21 is provided at the subsequent stage of the optical system 10 and includes a first light shielding plate 211 that shields the laser beam L from one side or both sides in the first direction. Specifically, the first light shielding plate 211 is provided on both sides or one side in the first direction of the space through which the laser beam L passes, and moves in the first direction toward the space through which the laser beam L passes. According to this, the first light shielding plate 211 can reduce the shape of the laser beam L incident on the photomask 22 from one side or both sides in the first direction by shielding the laser beam L from one side or both sides in the first direction. The first light shielding plate 211 may be composed of, for example, a black plate or a metal plate that does not transmit the laser beam L.

[0019] The photomask 22 is provided at the subsequent stage of the light shielding part 21 and shapes the laser beam L into a plurality of laser spots LS. Specifically, the photomask 22 is composed of, for example, a glass substrate laminated with a metal film in which a plurality of openings 22H are formed. The photomask 22 can shape the laser beam L into a plurality of laser spots LS by shielding the irradiated laser beam L with the metal film and transmitting it through the plurality of openings 22H.

[0020] The plurality of openings 22H formed in the photomask 22 are provided side by side in the first direction. For example, the plurality of openings 22H may be rectangular or circular openings arranged in one or multiple rows at a predetermined interval in the first direction. The laser spots LS transmitted through the photomask 22 are irradiated onto the semiconductor chips Cp formed in a matrix on the object 30. Therefore, the plurality of openings 22H are provided at positions corresponding to the semiconductor chips Cp formed in a matrix on the object 30. Thereby, the laser light irradiation device 1 can irradiate the plurality of semiconductor chips Cp provided on the object 30 with the laser spots LS simultaneously.

[0021] The condensing member 23 is provided at the subsequent stage of the photomask 22 and condenses the plurality of laser spots LS transmitted through the photomask 22 respectively. The condensing member 23 can ensure sufficient energy density for processing the object 30 (i.e., laser lift-off) by increasing the energy density of the plurality of laser spots LS through condensing. The condensing member 23 may be, for example, a microlens array. When the condensing member 23 is a microlens array, the condensing member 23 can reduce only the spot diameter without changing the interval between the plurality of laser spots LS. According to this, since the interval between the plurality of laser spots LS irradiated onto the object 30 can be determined by the interval between the plurality of openings 22H provided in the photomask 22, the laser light irradiation device 1 can simplify the design of the condensing member 23.

[0022] The stage 31 is provided at the subsequent stage of the condensing member 23, and the object 30 irradiated with the laser spot LS is placed thereon. The stage 31 is provided so as to be movable at a constant speed in the second direction orthogonal to the first direction. According to this, the laser light irradiation device 1 can irradiate a plurality of laser spots LS at equal intervals in the second direction by irradiating the laser light L from the light source 11 at a predetermined frequency in synchronization with the movement of the stage 31.

[0023] Since the multiple laser spots LS are aligned in the first direction, the laser irradiation device 1 can simultaneously irradiate each of the multiple semiconductor chips Cp arranged in the first direction (column direction) on the object 30 with the laser spots LS. Furthermore, by moving the stage 31 in the second direction, the laser irradiation device 1 can continuously irradiate each of the multiple semiconductor chips Cp arranged in the second direction (row direction) with the laser spots LS. Therefore, the laser irradiation device 1 can efficiently irradiate the semiconductor chips Cp arranged in a matrix in the first and second directions with the laser spots LS.

[0024] Furthermore, when stage 31 moves from one end in the second direction to the other end on the opposite side, it moves a predetermined distance in the first direction, and then repeats the movement from one end to the other in the second direction, or from the other end to the first end in the second direction. As a result, the laser beam irradiation device 1 can irradiate the entire surface of the object 30 with the laser spot LS.

[0025] The control device 40 includes a stage control unit 41 and a light source control unit 42. The control device 40 controls the position on the stage 31 to which the laser spot LS is irradiated by synchronously controlling the movement of the stage 31 and the emission of laser light L from the light source 11.

[0026] The stage control unit 41 controls the direction and speed of movement of the stage 31. The stage control unit 41 also generates a laser synchronization signal to pulse the laser light L from the light source 11 each time the stage 31 moves a predetermined distance in the second direction. For example, if the object 30 has semiconductor chips Cp arranged at a predetermined pitch P in the second direction, the stage control unit 41 may generate a laser synchronization signal each time the stage 31 moves n × P (where n is an integer of 1 or more) in the second direction.

[0027] The light source control unit 42 controls the emission of laser light L from the light source 11. Specifically, the light source control unit 42 may emit laser light L from the light source 11 by causing the light source 11 to pulse oscillate using a laser synchronization signal input from the stage control unit 41 as a trigger.

[0028] The configuration of the laser light irradiation device 1 according to this embodiment has been described above. The laser light irradiation device 1 according to this embodiment can efficiently irradiate each of a plurality of semiconductor chips Cp arranged in a matrix in the first and second directions with a plurality of laser spots LS.

[0029] <2. Effects> Next, the effects of the laser light irradiation device 1 according to this embodiment will be explained with reference to Figures 2 and 3. Figure 2 is an explanatory diagram showing how the laser light L emitted from the light source 11 is formed into laser spots LS. Figure 3 is an explanatory diagram showing the relationship between the irradiation area R irradiated by multiple laser spots LS and the object 30 in the XY plane.

[0030] As shown in Figure 2, first, a line-shaped laser beam L extending in the Y direction (corresponding to the first direction) is emitted from the optical system 10. The laser beam L emitted from the optical system 10 passes through apertures 22H provided in the photomask 22 in the Y direction, and is formed into a plurality of laser spots LS aligned in the Y direction. The plurality of laser spots LS aligned in the Y direction are each focused by the focusing member 23 and then irradiated onto the object 30.

[0031] Here, a light-shielding section 21, including a first light-shielding plate 211, is provided between the optical system 10 and the photomask 22. The first light-shielding plate 211 is provided so as to be movable on one or both sides in the Y direction of the space through which the laser light L passes, and can shield the laser light L emitted from the optical system 10 from both or one side in the Y direction by any width. Therefore, the laser light irradiation device 1 can shield the laser light L incident on the aperture 22H provided in the photomask 22 from both or one side in the Y direction. Thus, the laser light irradiation device 1 can reduce the number of multiple laser spots LS passing through the aperture 22H sequentially from both or one side in the Y direction by moving the first light-shielding plate 211 to shield the laser light L incident on the aperture 22H.

[0032] On the other hand, as shown in Figure 3, the laser irradiation device 1 moves the stage 31 in the X direction (corresponding to the second direction), which is perpendicular to the Y direction, to scan the irradiation area R, which is irradiated by multiple laser spots LS aligned in the Y direction, in the X direction, thereby irradiating the entire surface of the object 30 with multiple laser spots LS.

[0033] For example, in object 30, if the chip region 30A on which the semiconductor chip Cp is provided is a polygon other than a rectangle (for example, a hexagon), then the chip region 30A has a hypotenuse Ht that intersects the X and Y directions at an oblique angle. In the vicinity of the hypotenuse Ht, the number of semiconductor chips Cp arranged in rows or columns will decrease or increase monotonically depending on the slope of the hypotenuse Ht.

[0034] The laser irradiation device 1 according to this embodiment can reduce the shape of the irradiation area R in the Y direction, so that the shape of the irradiation area R can be changed to match the arrangement of semiconductor chips Cp along the hypotenuse Ht. As a result, when the irradiation area R is scanned in the X direction, the laser irradiation device 1 can change the shape of the irradiation area R in the Y direction near the hypotenuse Ht, thereby irradiating the semiconductor chips Cp with multiple laser spots LS without any overhang or gaps. Therefore, the laser irradiation device 1 can more efficiently irradiate the semiconductor chips Cp provided on the object 30 with multiple laser spots LS.

[0035] <3. Variant> Next, a modified example of the laser light irradiation device 1 will be described with reference to Figures 4 and 5. Figure 4 is an explanatory diagram showing the configuration of the laser light irradiation device 1A according to this modified example. Figure 5 is an explanatory diagram showing the relationship between the irradiation area R, to which the multiple laser spots LS in this modified example are irradiated, and the object 30 in the XY plane.

[0036] As shown in Figure 4, the laser light irradiation device 1A according to this modified example differs from the laser light irradiation device 1 shown in Figure 1 in that the light shielding section 21 further includes a second light shielding plate 212 in addition to the first light shielding plate 211, which shields the laser light L from one or both sides in the second direction.

[0037] The second light-shielding plate 212 is provided on one or both sides of the space through which the laser beam L passes in the second direction, and is movable in the second direction toward the space through which the laser beam L passes. As a result, the second light-shielding plate 212 can reduce the shape of the laser beam L incident on the photomask 22 from one or both sides of the second direction by shielding the laser beam L from one or both sides of the second direction. The second light-shielding plate 212 may be made of, for example, a black plate or a metal plate that does not transmit the laser beam L.

[0038] The laser beam irradiation device 1A according to this modified example is capable of reducing the shape of the laser beam L in the first and second directions, respectively, by the first light-shielding plate 211 and the second light-shielding plate 212.

[0039] In other words, as shown in Figure 5, the laser beam irradiation device 1A can reduce the irradiation area R, which is irradiated by multiple laser spots LS, in two axial directions, the X direction and the Y direction. For example, suppose the irradiation area R has rows of multiple laser spots LS arranged in the Y direction, extending in multiple rows in the X direction. In such a case, the laser beam irradiation device 1A can reduce the length of the rows of multiple laser spots LS arranged in the Y direction by moving the first light-shielding plate 211 to reduce the shape of the laser beam L in the first direction (i.e., the Y direction). Furthermore, the laser beam irradiation device 1A can reduce the number of rows of multiple laser spots LS by moving the second light-shielding plate 212 to reduce the shape of the laser beam L in the second direction (i.e., the X direction).

[0040] The modified laser irradiation device 1A can more flexibly change the shape of the irradiation area R to which the multiple laser spots LS are irradiated in the X and Y directions. Therefore, the modified laser irradiation device 1A can more efficiently irradiate each of the multiple semiconductor chips Cp provided on the object 30 with multiple laser spots LS.

[0041] Although preferred embodiments of the present invention have been described in detail above with reference to the attached drawings, the present invention is not limited to these examples. It is clear to any person with ordinary skill in the art to which the present invention belongs that various modifications or alterations can be conceived within the scope of the technical idea described in the claims, and these are also understood to fall within the technical scope of the present invention. [Explanation of Symbols]

[0042] 1,1A…Laser beam irradiation device, 10…Optical system, 21…Shading section, 211…First light-shielding plate, 212…Second light-shielding plate, 22…Photomask, 22H…Aperture, 23…Focusing member, 30…Object, 31…Stage, 40…Control device, L…Laser beam, LS…Laser spot, Cp…Semiconductor chip

Claims

1. An optical system that shapes laser light emitted from a light source into a longitudinal shape extending in a first direction, A light-shielding portion including a first light-shielding plate that is movable in the first direction and shields the laser light from one or both sides in the first direction, A photomask is provided downstream of the light-shielding section and shapes the laser beam into a plurality of laser spots aligned in the first direction, A stage on which an object to be illuminated by the plurality of laser spots is placed and moves in a second direction perpendicular to the first direction, A laser beam irradiation device equipped with the following features.

2. The laser light irradiation device according to claim 1, wherein the stage moves at a constant speed in synchronization with the irradiation frequency of the laser light.

3. The laser light irradiation device according to claim 1, wherein the plurality of laser spots irradiate a plurality of semiconductor chips provided on the object.

4. The laser light irradiation apparatus according to claim 3, wherein the plurality of semiconductor chips and a part of the object are separated by irradiation of the plurality of laser spots.

5. The laser light irradiation device according to claim 3, wherein the plurality of semiconductor chips are arranged in a matrix in the first and second directions.

6. The laser light irradiation device according to any one of claims 1 to 5, further comprising a focusing member provided downstream of the photomask for focusing the plurality of laser spots to the irradiation position of the object.

7. The laser light irradiation device according to claim 6, wherein the light-collecting member is a microlens array.

8. The laser beam irradiation device according to any one of claims 1 to 5, wherein the light-shielding portion further includes a second light-shielding plate that is movable in the second direction and shields the laser beam from one or both sides in the second direction.

9. A step of shaping the laser beam emitted from the light source into a longitudinal shape extending in a first direction, A step of shielding the laser light from one or both sides in the first direction with a first light-shielding plate that is movable in the first direction, The steps include: shaping the laser beam into a plurality of laser spots aligned in a first direction using a photomask provided downstream of the first light-shielding plate; The steps include irradiating an object placed on a stage that moves in a second direction perpendicular to the first direction with the plurality of laser spots, A laser light irradiation method, including the following.

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