Laser device

Abstract

A laser device is provided. The laser device according to an embodiment includes a laser module that emits a laser beam, a first optical system that expands a size of the laser beam emitted from the laser module in a first direction that intersects with an emission direction and emits the laser beam, a second optical system that causes a plurality of sub-beams that split the laser beam emitted from the first optical system in the first direction to be arranged in a second direction that intersects with the emission direction and the first direction and emit the sub-beams, a third optical system that homogenizes energy of the laser beam emitted from the second optical system in the first direction, and a fourth optical system that reduces the size of the laser beam emitted from the third optical system in the first direction.

Description

TECHNICAL FIELD

[0001] The present application relates to a laser device. BACKGROUND

[0002] With the development of multimedia, the importance of display devices is increasing. In response to this, various display devices such as an organic light emitting display (OLED), a liquid crystal display (LCD), and the like are being used.

[0003] The above-described display device can control whether or not each pixel emits light and the degree of light emission using a thin film transistor. The thin film transistor includes a semiconductor layer, a gate electrode, and a source / drain electrode, and polycrystalline silicon (poly-Si) that is crystallized from amorphous silicon (a-Si) is mainly used for the semiconductor layer. As a method of crystallizing amorphous silicon (a-Si) into polycrystalline silicon (p-Si), a method of crystallizing amorphous silicon (a-Si) by irradiating a laser beam is used. SUMMARY

[0004] The present application has been made to solve the above-mentioned problems, and provides a laser device for manufacturing a display device having uniform quality and excellent performance.

[0005] The technical problems of the present application are not limited to the above-mentioned technical problems, and other technical problems not mentioned herein will be clearly understood by those skilled in the art from the following description.

[0006] A laser device according to an embodiment for solving the above-mentioned technical problems includes: a laser module that emits a laser beam; a first optical system that expands a size of the laser beam emitted from the laser module in a first direction that intersects with an emission direction and emits the laser beam; a second optical system that causes a plurality of sub-beams that split the laser beam emitted from the first optical system in the first direction to be emitted in a second direction that intersects with the emission direction and the first direction; a third optical system that homogenizes energy of the laser beam emitted from the second optical system in the first direction; and a fourth optical system that reduces a size of the laser beam emitted from the third optical system in the first direction.

[0007] The second optical system can exchange the size of the laser beam in the first direction and the size in the second direction and emit the laser beam.

[0008] The second optical system can maintain a beam quality factor of the laser beam in the first direction and the second direction and exchange the sizes in the first direction and the second direction.

[0009] The third optical system can include a first short axis homogenizer including a cylindrical lens array in which an incident surface is convex in a direction opposite to the emission direction and an emission surface is a planar structure; a second short axis homogenizer disposed on the other side of the first short axis homogenizer and including a cylindrical lens array in which an incident surface is a planar structure and an emission surface is convex in the emission direction; and a third short axis homogenizer disposed on the other side of the second short axis homogenizer and including a lens in which an incident surface is a planar structure and an emission surface is convex in the emission direction.

[0010] The laser device can further include a fifth optical system to homogenize energy of the laser beam in the second direction.

[0011] The fifth optical system can include a first long axis homogenizer including a cylindrical lens array in which an incident surface is convex in a direction opposite to the emission direction and an emission surface is a planar structure; a second long axis homogenizer disposed on the other side of the first long axis homogenizer and including a cylindrical lens array in which an incident surface is a planar structure and an emission surface is convex in the emission direction; and a third long axis homogenizer disposed on the other side of the second long axis homogenizer and including a lens in which an incident surface is a planar structure and an emission surface is convex in the emission direction.

[0012] The laser beam passing through the second optical system can be incident to the fifth optical system.

[0013] The fourth optical system can include a cylindrical convex lens extending in the second direction and in which an incident surface is convex in a direction opposite to the emission direction.

[0014] The laser beam emitted from the fourth optical system can form a focal point on an upper surface of an object substrate.

[0015] The laser beam before passing through the first optical system can maintain a beam quality factor with respect to the second direction and reduce a beam quality factor with respect to the first direction.

[0016] Details of other embodiments are included in the detailed description and the accompanying drawings.

[0017] The laser device according to an embodiment can form a narrow short axis size with a high energy density and ensure a sufficient focal depth to provide a laser beam having uniform energy in each region in a short axis direction.

[0018] Effects according to embodiments of the present application are not limited to what has been described above, and include a variety of effects. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a plan view of a display device according to an embodiment.

[0020] Figure 2 is a cross-sectional view of a portion of a display device schematically illustrating Figure 1 .

[0021] Figure 3 is a perspective view of a laser device according to an embodiment.

[0022] Figure 4 is a schematic view of a substrate irradiated by a laser beam emitted from a laser device according to an embodiment, enlarged.

[0023] Figure 5 is a flowchart showing a movement path of a laser beam in a laser device according to an embodiment.

[0024] Figure 6 is a schematic view of a laser beam passing through a telescope lens section.

[0025] Figure 7 is a simulation result regarding energy of a laser beam passing through a telescope lens section.

[0026] Figure 8 is a schematic view of a laser beam passing through a beam quality factor conversion section.

[0027] Figure 9 is a simulation result regarding energy of a laser beam passing through a beam quality factor conversion section.

[0028] Figure 10 is a schematic view of a laser beam passing through a short axis homogenizer section.

[0029] Figure 11 is a schematic view of a laser beam passing through a long axis homogenizer section.

[0030] Figure 12 is a schematic view of a laser beam passing through a projection lens section.

[0031] Figure 13 is a graph of an energy characteristic of a laser beam of a laser device according to an embodiment.

[0032] Figure 14 and Figure 15 is a graph of an energy characteristic of a laser beam of a laser device according to a comparative embodiment.

[0033] Figure 16 is a flowchart showing a manufacturing method of a display device according to an embodiment.

[0034] BRIEF DESCRIPTION OF DRAWINGS

[0035] 10: substrate 11: amorphous silicon thin film

[0036] 12: polycrystal silicon thin film 100: laser module

[0037] 200: Telescope lens section; 300: Beam quality factor conversion section

[0038] 400: Short-axis homogenizer section; 500: Long-axis homogenizer section

[0039] 600: Projection Lens Section Detailed Implementation

[0040] The advantages and features of the invention, as well as the methods for achieving them, will become clear from the accompanying drawings and detailed embodiments described below. However, the invention can take many different forms and is not limited to the embodiments disclosed below. These embodiments are provided only to fully disclose the invention and to completely inform those skilled in the art of the invention of its scope, which is defined only by the scope of the claims.

[0041] When referring to an element or layer "on" other elements or layers, this includes cases where it is immediately above or between other elements. Throughout the specification, the same reference numerals refer to the same constituent elements.

[0042] Although terms such as "first" and "second" are used to describe various constituent elements, these constituent elements should not be limited by these terms. These terms are used only for the purpose of distinguishing one constituent element from another. Therefore, the "first constituent element" mentioned below can also be a "second constituent element" within the technical concept of this invention.

[0043] Hereinafter, embodiments will be described with reference to the accompanying drawings.

[0044] Figure 1 This is a plan view of a display device according to one embodiment. Figure 2 It is a schematic diagram. Figure 1 A cross-sectional view of a portion of the display device.

[0045] refer to Figure 1 and Figure 2 A display device (DD) displays video or still images. A display device (DD) can refer to all electronic devices that provide a display screen. For example, televisions, laptops, monitors, billboards, IoT devices, mobile phones, smartphones, tablets (PCs), electronic watches, smartwatches, watch phones, head-mounted displays, mobile communication terminals, electronic notebooks, e-books, portable multimedia players (PMPs), navigators, game consoles, digital cameras, and camcorders can all be included in a display device (DD).

[0046] The shape of the display device DD can be variously deformed. For example, the display device DD can have a rectangular shape with a longer lateral length, a rectangular shape with a longer vertical length, a square shape, a quadrilateral shape with rounded corners (apexes), other polygonal shapes, a circular shape, or the like. The shape of the display area DPA of the display device DD can also be similar to the overall shape of the display device DD. Figure 1 A display device DD and a display area DPA in a rectangular shape with a longer lateral length are exemplified.

[0047] The display device DD can include a display area DPA and a non-display area NDA. The display area DPA is an area in which an image can be displayed, and the non-display area NDA is an area in which an image is not displayed. The display area DPA can also be referred to as an active area, and the non-display area NDA can also be referred to as an inactive area. The display area DPA can substantially occupy the center of the display device DD.

[0048] The display area DPA can include a plurality of pixels PX. The plurality of pixels PX can be arranged in a row and column direction.

[0049] The non-display area NDA can be disposed around the display area DPA. The non-display area NDA can completely or partially surround the display area DPA. The display area DPA can be in a rectangular shape, and the non-display area NDA can be disposed adjacent to the four sides of the display area DPA.

[0050] The display device DD can include a display panel DP. The display panel DP is a panel that displays a screen or an image, and for example, can include not only a self-emission display panel such as an organic light-emitting display panel (OLED), an inorganic EL display panel, a quantum dot light-emitting display panel (QED), a micro-LED display panel (micro-LED), a nano-LED display panel (nano-LED), a plasma display panel (PDP), a field emission display panel (FED), a cathode ray tube display panel (CRT), or the like, but also a light-receiving display panel such as a liquid crystal display panel (LCD), an electrophoretic display panel (EPD), or the like. Hereinafter, a case in which the display panel DP is an organic light-emitting display panel is exemplified, but is not limited thereto.

[0051] The display panel DP can include a base substrate SUB1, a buffer layer SUB2, a semiconductor layer ACT, a first insulating layer IL1, a first gate conductive layer 621, a second insulating layer IL2, a second gate conductive layer 622, a third insulating layer IL3, a data conductive layer 623, a fourth insulating layer IL4, an anode electrode ANO, a pixel definition film PDL including an opening portion exposing the anode electrode ANO, an emission layer EML arranged in the opening portion of the pixel definition film PDL, a cathode electrode CAT arranged on the emission layer EML and the pixel definition film PDL, and a thin film encapsulation layer EN arranged on the cathode electrode CAT. Although each of the above-described layers can be configured as a single layer film, it can also be configured as a laminated film including a plurality of layer films. Other layers can also be arranged between each of the layers.

[0052] The base substrate SUB1 can support each of the layers arranged on an upper portion thereof. The base substrate SUB1 can also be formed of an insulating material such as a polymer resin or an inorganic material such as glass or quartz.

[0053] The buffer layer SUB2 is arranged on the base substrate SUB1. The buffer layer SUB2 can include silicon nitride, silicon oxide, silicon oxynitride, or the like.

[0054] The semiconductor layer ACT is arranged on the buffer layer SUB2. The semiconductor layer ACT can constitute a channel of a thin film transistor of a pixel. The semiconductor layer ACT can include polycrystalline silicon crystallized by a laser device (refer to "LD" of Figure 3 hereinafter). The semiconductor layer ACT can be obtained by crystallizing an amorphous silicon film (refer to "11" of Figure 3 hereinafter) arranged on an object substrate (refer to "10" of Figure 3 hereinafter) in its entirety and then patterning the same, or by patterning the amorphous silicon film (refer to "11" of Figure 3 hereinafter) and then crystallizing the patterned amorphous silicon film (refer to "11" of Figure 3 hereinafter). However, it is not limited thereto, and although not illustrated, only a portion of the amorphous silicon film (refer to "11" of Figure 3 hereinafter) can be crystallized, such that the semiconductor layer ACT includes an amorphous silicon region (not illustrated) in which amorphous silicon is arranged and a polycrystalline silicon region (not illustrated) in which polycrystalline silicon is arranged.

[0055] The first insulating layer IL1 can be arranged on the semiconductor layer ACT. The first insulating layer IL1 can be a first gate insulating film having a gate insulating function.

[0056] The first gate conductive layer 621 can be arranged on the first insulating layer IL1. The first gate conductive layer 621 can include a gate electrode GAT of a thin film transistor of a pixel, a scan line connected to the gate electrode GAT, and a capacitor first electrode CE1.

[0057] A second insulating layer IL2 can be arranged on the first gate conductive layer 621. The second insulating layer IL2 can be an interlayer insulating film or a second gate insulating film.

[0058] A second gate conductive layer 622 can be arranged on the second insulating layer IL2. The second gate conductive layer 622 can include a capacitor second electrode CE2.

[0059] A third insulating layer IL3 can be arranged on the second gate conductive layer 622. The third insulating layer IL3 can be an interlayer insulating film.

[0060] A data conductive layer 623 can be arranged on the third insulating layer IL3. The data conductive layer 623 can include a first electrode SD1 and a second electrode SD2 of a thin film transistor of a pixel and a first power supply line ELVDD. The first electrode SD1 and the second electrode SD2 of the thin film transistor can be electrically connected to a source region and a drain region of a semiconductor layer ACT through a contact hole that penetrates the third insulating layer IL3, the second insulating layer IL2, and the first insulating layer IL1.

[0061] A fourth insulating layer IL4 can be arranged on the data conductive layer 623. The fourth insulating layer IL4 can cover the data conductive layer 623. The fourth insulating layer IL4 can be a via layer.

[0062] An anode electrode ANO can be arranged on the fourth insulating layer IL4. The anode electrode ANO can be a pixel electrode provided in each pixel. The anode electrode ANO can be connected to the second electrode SD2 of the thin film transistor through a contact hole that penetrates the fourth insulating layer IL4.

[0063] A pixel defining film PDL can be arranged on the anode electrode ANO and include an opening portion that exposes the anode electrode ANO. A light emitting region EMA and a non-light emitting region NEM can be distinguished by the pixel defining film PDL and the opening portion thereof.

[0064] A spacer SP can be arranged on the pixel defining film PDL. The spacer SP can function to maintain a gap between a structure arranged on an upper portion thereof.

[0065] A light emitting layer EML can be arranged on the anode electrode ANO that exposes the pixel defining film PDL. The light emitting layer EML can include an organic substance layer. The organic substance layer of the light emitting layer EML can include an organic light emitting layer, and can further include a hole injection / transport layer and / or an electron injection / transport layer.

[0066] A cathode electrode CAT can be arranged on the light-emitting layer EML. The cathode electrode CAT can be a common electrode arranged on the entire surface without distinguishing the pixels. The anode electrode ANO, the light-emitting layer EML, and the cathode electrode CAT can constitute each organic light-emitting element.

[0067] A thin film encapsulation layer EN including a first inorganic film EN1, a first organic film EN2, and a second inorganic film EN3 is arranged on the cathode electrode CAT. At the end portion of the thin film encapsulation layer EN, the first inorganic film EN1 and the second inorganic film EN3 can be in contact with each other. The first organic film EN2 can be sealed by the first inorganic film EN1 and the second inorganic film EN3.

[0068] The first inorganic film EN1 and the second inorganic film EN3 can each include a silicon nitride, a silicon oxide, or a silicon oxynitride, or the like. The first organic film EN2 can include an organic insulating substance.

[0069] Hereinafter, a laser device that forms a polycrystal silicon thin film included in the above-described semiconductor layer ACT will be described. Specifically, the laser device described later can be a device that crystallizes an amorphous silicon thin film into a polycrystal silicon thin film.

[0070] Figure 3 is a perspective view of a laser device according to an embodiment. Figure 4 is a schematic view of a substrate irradiated by a laser beam emitted from a laser device according to an embodiment.

[0071] Referring to Figure 3 and Figure 4 An amorphous silicon thin film 11 can be arranged on an object substrate 10. The object substrate 10 can be a glass substrate or a flexible substrate. The flexible substrate can be one of a polyethylene terephthalate (PET) film, a polypropylene (PP) film, a polyethylene (PE) film, a polyimide (PI) film, a polystyrene (PS) film, a polycarbonate (PC) film, a polyethylene naphthalate (PEN) film, a cyclic olefin copolymer (COC) film, or an acryl film.

[0072] In the present specification, a case where the amorphous silicon thin film 11 is formed on the object substrate 10 and crystallized by a laser device LD is described as an example, but the amorphous silicon thin film 11 can be an amorphous semiconductor layer including another substance in addition to silicon.

[0073] The amorphous silicon thin film 11 can be formed by a chemical vapor deposition (CVD) method or a plasma chemical vapor deposition method, etc. The amorphous silicon thin film 11 can have a uniform thickness in each region, but is not limited thereto, and the upper and lower surfaces of the amorphous silicon thin film 11 can include concave-convex portions and have different thicknesses in microstructures in each region. Hereinafter, a detailed description will be made with reference to Figure 4 a detailed description thereof.

[0074] For example, the amorphous silicon thin film 11 can be formed using silicon or a silicon-based substance (e.g., Si x Ge (1-x) ).

[0075] The laser device LD according to an embodiment can be a device that provides a laser beam LB. When the laser beam LB is provided using the laser device LD, it can be located at one side of the object substrate 10. For example, the laser device LD can be located at an upper portion of the object substrate 10 irradiated with the laser beam LB.

[0076] The laser device LD can irradiate the laser beam LB to the amorphous silicon thin film 11 located on the object substrate 10. The amorphous silicon thin film 11 irradiated with the laser beam LB can be crystallized into a polycrystalline silicon thin film 12. In order to effectively crystallize the amorphous silicon thin film 11, a large amount of energy can be required. Therefore, it is preferable to provide a large amount of energy per unit area to a region irradiated with the laser beam LB.

[0077] When the amorphous silicon thin film 11 is crystallized at a temperature lower than a melting point, abnormal convex shapes formed at grain boundaries are reduced, and thus crystallinity can be improved. Therefore, it is preferable to heat the amorphous silicon thin film 11 to a temperature lower than a melting point of the amorphous silicon thin film 11. For example, in the case where the amorphous silicon thin film 11 has a melting temperature of about 1460°C, the laser beam LB can be controlled to heat the amorphous silicon thin film 11 to a temperature of about 1300°C to 1400°C.

[0078] The laser beam LB can be irradiated to the amorphous silicon thin film 11 for several nanoseconds (ns). The amorphous silicon included in the amorphous silicon thin film 11 can be rapidly increased in temperature and melted by the irradiated laser beam LB, and then be cooled to be recrystallized. Through the above-described method, the amorphous silicon thin film 11 can be crystallized into the polycrystalline silicon thin film 12 by the laser beam LB. The amorphous silicon thin film 11 repeatedly performs melting and recrystallization, and concave-convex portions are generated on the surface, and thus the surface roughness can be increased. That is, the surface roughness of the polycrystalline silicon thin film 12 can be greater than that of the amorphous silicon thin film 11.

[0079] The laser beam LB can be emitted in a linear beam shape extending in one direction. In an exemplary embodiment, the laser beam LB can be emitted in the third direction DR3. The linear shape of the laser beam LB can extend in the first direction DR1 perpendicular to the third direction DR3 as the emission direction. The first direction DR1 as the direction of extension of the laser beam LB can be referred to as a major axis direction, and the length in the first direction DR1 can be referred to as a major axis dimension Dx. The larger the major axis dimension Dx, the wider area of the amorphous silicon thin film 11 can be crystallized. The major axis dimension Dx can be determined by an optical system included in the laser device LD described later.

[0080] Further, the second direction DR2 as the thickness direction perpendicular to the direction of extension of the laser beam LB can be referred to as a minor axis direction, and the length in the second direction DR2 can be referred to as a minor axis dimension Dy. The smaller the minor axis dimension Dy, the larger the energy per unit area can be provided to the amorphous silicon thin film 11. For example, the minor axis dimension Dy of the laser beam LB can be about 400 μm or less, or about 200 μm or less, or about 150 μm or less, or about 100 μm or less, but is not limited thereto.

[0081] Although not illustrated, the object substrate 10 on which the amorphous silicon thin film 11 is formed can be located on a moving tray (not illustrated). During irradiation of the laser beam LB, the moving tray (not illustrated) can constantly move the object substrate 10 in the arrow direction, so that the laser beam LB is uniformly irradiated to the amorphous silicon thin film 11 on the object substrate 10.

[0082] As another example, the laser device LD can move and irradiate the laser beam LB in a state where the object substrate 10 on which the amorphous silicon thin film 11 is formed is stationary. As still another example, the laser device LD and the object substrate 10 on which the amorphous silicon thin film 11 is formed can move together and irradiate the laser beam LB. At this time, the moving speed of the laser device LD and the moving speed of the object substrate 10 on which the amorphous silicon thin film 11 is formed can be the same, but are not limited thereto and can move at different speeds.

[0083] The laser beam LB emitted from the laser device LD can provide the maximum energy at the focal point. As described above, the more the amount of energy provided from the laser beam LB, the more effectively the crystallization of the amorphous silicon thin film 11 can be achieved. Therefore, in order to achieve effective silicon crystallization, it is preferable that the focal point of the laser beam LB be formed inside the amorphous silicon thin film 11. For example, the focal point of the laser beam LB can be located at the center in the thickness direction inside the amorphous silicon thin film 11, but is not limited thereto and can be disposed offset to one side or the other side of the third direction DR3 from the center in the thickness direction inside the thin film.

[0084] The upper surface and the lower surface of the silicon thin films 11, 12 can include concave-convex portions. The upper surface of the silicon thin films 11, 12 can include a high point HP that is most convex toward the other side of the third direction DR3, and the lower surface of the silicon thin films 11, 12 can include a low point LP that is most convex toward the one side of the third direction DR3.

[0085] In order to realize uniform crystallization of the amorphous silicon thin film 11, it is necessary to provide uniform energy by region. It is possible to provide substantially uniform energy to a region from the focal plane to within the focal depth (DOF: depth of focus) of the focal point of the laser beam LB. The focal depth (DOF: depth of focus) indicates a distance that is considered to be in focus even if the focal plane is moved away from or close to the focal plane, and the larger the value of the focal depth (DOF: depth of focus) of the laser beam LB, the wider the region in which the energy provided is substantially the same as the energy provided to the focal plane. That is, in order to realize uniform crystallization of the amorphous silicon thin film 11, it is preferable that the focal point of the laser beam LB be formed inside the amorphous silicon thin film 11, and the focal depth (DOF: depth of focus) of the laser beam LB be at least larger than the step difference d between the high point HP and the low point LP.

[0086] Figure 5 is a flowchart showing a movement path of a laser beam in a laser device according to an embodiment.

[0087] Referring to Figure 5 , the laser device LD according to an embodiment can include a laser module 100 that emits a laser beam LB, a telescope lens portion 200 that emits the laser beam LB in a state in which the size in the second direction (short axis direction) DR2 is expanded, a beam quality factor conversion portion 300 that arranges and emits a plurality of sub-beams that split the laser beam LB in the second direction (short axis direction) DR2 in the first direction (long axis direction) DR1, a short axis homogenizer portion 400 that homogenizes the energy of the laser beam LB in the second direction (short axis direction) DR2, a long axis homogenizer portion 500 that homogenizes the energy of the laser beam LB in the first direction (long axis direction) DR1, and a projection lens portion 600 that reduces the size of the laser beam LB in the second direction (short axis direction) DR2.

[0088] In an embodiment, the laser beam LB output from the laser module 100 can be sequentially irradiated onto the object substrate 10 via the telescope lens portion 200, the beam quality factor conversion portion 300, the short axis homogenizer portion 400, the long axis homogenizer portion 500, and the projection lens portion 600. The telescope lens portion 200, the beam quality factor conversion portion 300, the short axis homogenizer portion 400, and the projection lens portion 600 can be arranged so that the laser beam LB sequentially passes therethrough, but the position of the long axis homogenizer portion 500 is not limited thereto.

[0089] In another embodiment, the long-axis equalizer section 500 may be arranged between the telescope lens section 200 and the beam quality factor conversion section 300. In yet another embodiment, the long-axis equalizer section 500 may be arranged between the beam quality factor conversion section 300 and the short-axis equalizer section 400.

[0090] The first laser beam LB1 (refer to) can be output from the laser module 100 of the laser device LD. Figure 6 The first laser beam LB1 can have a linear shape. The first laser beam LB1 can form a beam spot on the irradiated surface. The energy distribution of the first laser beam LB1 output from the laser module 100 can have a Gaussian distribution with higher energy at the center. The first laser beam LB1 is a circular beam, and its major axis dimension (not shown) and minor axis dimension Dy1 can be approximately the same. The laser module 100 can use excimer lasers, YAG lasers, glass lasers, YVO4 lasers, Ar lasers, ruby ​​lasers, etc. However, it is not limited to these; in addition to the lasers mentioned above, any laser capable of crystallizing silicon can be used by the laser module 100.

[0091] The limitations of each component of the aforementioned laser device LD are explained in more detail below.

[0092] Figure 6 This is a schematic diagram showing a laser beam passing through the lens of a telescope. Figure 7 It is a simulation result about the energy of the laser beam passing through the lens of the telescope. Figure 8 This is a schematic diagram showing a laser beam passing through the beam quality factor conversion section. Figure 9 It is a simulation result regarding the energy of the laser beam passing through the beam quality factor conversion section. Figure 10 This is a schematic diagram showing a laser beam passing through the short-axis homogenizer section. Figure 11 This is a schematic diagram showing a laser beam passing through the long-axis homogenizer section. Figure 12 This is a schematic diagram showing a laser beam passing through the projection lens.

[0093] Reference Figure 5 , Figure 6 and Figure 7 A first laser beam LB1 can be output from the laser module 100 and incident on the telescope lens section 200 along a third direction DR3. The telescope lens section 200 can extend the first laser beam LB1 in a second direction (or, the minor axis direction) DR2. The first laser beam LB1 can be extended by the telescope lens section 200 in the second direction (or, the minor axis direction) DR2 to become a second laser beam LB2. The minor axis dimension Dy2 of the second laser beam LB2 can be larger than the minor axis dimension Dy1 of the first laser beam LB1.

[0094] The telescope lens portion 200 can include a first telescope lens 210 and a second telescope lens 220. The first telescope lens 210 can be a cylindrical lens in which an incident surface is convex in the opposite direction of the third direction DR3 and an emission surface is flat. The first laser beam LB1 can be refracted in the second direction (short axis direction) DR2 by the first telescope lens 210 and focused to a focal point, and then dispersed.

[0095] The second telescope lens 220 can be a cylindrical lens in which an incident surface is flat and an emission surface is convex in the third direction DR3. The second telescope lens 220 can refract the first laser beam LB1, which is expanded in the second direction (short axis direction) DR2 by the first telescope lens 210, and then emit the second laser beam LB2, which is parallel in the third direction DR3.

[0096] As described above, the telescope lens portion 200 can expand the incident first laser beam LB1 in the second direction (short axis direction) DR2 and emit the second laser beam LB2. A long axis size Dx2 of the second laser beam LB2 can be the same as a long axis size (not shown) of the first laser beam LB1. However, as shown in FIG. 2B, the energy density of the second laser beam LB2 expanded by the telescope lens portion 200 can have a Gaussian distribution in which the energy is higher at the center portion, like the first laser beam LB1 incident to the telescope lens portion 200. Figure 7

[0097] In order to achieve efficient material processing, it is preferable to form a line beam having a higher energy density. To this end, it is necessary to reduce the spot size by a process of condensing or focusing in the second direction (short axis direction) DR2, thereby reducing the short axis size Dy of the laser beam LB.

[0098] The laser beam LB travels in a Gaussian form, and the spot size is defined as a size corresponding to twice the radius w0 at the beam waist. The beam waist can represent a region in which the diameter of the beam reaches a minimum value due to the diffraction of the Gaussian beam. The spot size 2w0 can be determined by [Equation 1] below, through a relationship between the wavelength λ of the laser beam LB, the size D of the laser beam LB incident to the lens, the focal length F of the lens, and the beam quality factor M 2

[0099] [Equation 1]

[0100]

[0101] Referring to Equation 1, if the beam quality factor M is reduced while the beam size D and the focal length F of the lens are maintained, the spot size 2w0 can be reduced.​​2 This can reduce the spot size by 2w0. Beam quality factor M 2 This is a quantitative numerical value for the focusing characteristics of a laser beam (LB), and can be a measure of the degree of variation from an ideal Gaussian beam. Beam quality factor M 2 It can have multiple values ​​depending on the direction. For example, the laser beam LB can have a long-axis beam quality factor Mx for the first direction (long axis direction) DR1. 2 Furthermore, DR2 has a short-axis beam quality factor My for the second direction (short-axis direction). 2 Long-axis beam quality factor Mx 2 Short-axis beam quality factor My 2 The major axis dimension Dx and the minor axis dimension Dy can satisfy the following formula 2.

[0102] [Formula 2]

[0103] Mx 2 My 2 DxDy = const (where const is a constant)

[0104] Referring to Formula 2, the second laser beam LB2 passing through the telescope lens section 200 can have a minor-axis beam quality factor My that is inversely proportional to the increase in minor-axis dimension Dy compared to the first laser beam LB1. 2 .

[0105] Reference Figure 5 , Figure 8 and Figure 9 The second laser beam LB2 emitted from the telescope lens section 200 can be incident on the beam quality factor conversion section 300 along the third direction DR3. The second laser beam LB2, which has a line beam shape extending along the second direction (minor axis direction) DR2, can be incident on the beam quality factor conversion section 300 and emitted as a third laser beam LB3, which has a line beam shape extending along the first direction (major axis direction) DR1.

[0106] The beam quality factor conversion unit 300 can cause the second laser beam LB2 to be repeatedly reflected, thereby shifting the position of the reflected second laser beam LB2 by a predetermined distance to achieve segmentation, thus allowing sub-beams of a predetermined size to be transmitted. For example, a beam having such... Figure 7 The second laser beam LB2, as shown in the diagram, is divided into n sub-beams along the second direction (minor axis direction) DR2, and these n sub-beams are arranged along the first direction (major axis direction) DR1, thereby emitting a beam with the energy distribution shown. Figure 9 The energy distribution of the third laser beam LB3 is shown. Based on this, it is possible to maintain the long-axis beam quality factor Mx. 2 and short-axis beam quality factor My 2while converting the long axis dimension Dx and the short axis dimension Dy to each other. That is, the beam quality factor conversion section 300 can receive the second laser beam LB2, and in turn emit a third laser beam LB3 having a long axis beam quality factor Mx 2 and a short axis beam quality factor My 2 while converting the long axis dimension Dx and the short axis dimension Dy to each other.

[0107] In an exemplary embodiment, the short axis dimension Dy3 of the third laser beam LB3 can be substantially the same as the long axis dimension Dx2 of the second laser beam LB2, and the long axis dimension Dx3 of the third laser beam LB3 can be substantially the same as the short axis dimension Dy2 of the second laser beam LB2, but is not limited thereto.

[0108] Referring to Figure 5 and Figure 10 The third laser beam LB3 emitted from the beam quality factor conversion section 300 can be incident to a short axis homogenizer section 400. The short axis homogenizer section 400 can include a first short axis homogenizer 410, a second short axis homogenizer 420, and a third short axis homogenizer 430. The short axis homogenizer section 400 can receive the third laser beam LB3 having a Gaussian distribution of energy density in the second direction (short axis direction) DR2, and in turn emit a fourth laser beam LB4 having a uniform energy density in the second direction (short axis direction) DR2.

[0109] The first short axis homogenizer 410 can be a convex lens array having an incident surface convex in the opposite direction of the third direction DR3 and an emission surface in a planar structure. The cylindrical lens array can be a structure in which a plurality of cylindrical lenses formed in the second direction (short axis direction) DR2 are continuously arranged. The cylindrical lens can include a spherical lens or an aspherical lens. The third laser beam LB3 can be incident to the first short axis homogenizer 410 and refracted by each cylindrical lens of the cylindrical lens array, and in turn be divided into a plurality of beams.

[0110] The second short axis homogenizer 420 can be arranged on the back surface of the first short axis homogenizer 410. The focal length of the first short axis homogenizer 410 can be shorter than the interval distance between the first short axis homogenizer 410 and the second short axis homogenizer 420. The divided beams can be dispersed again after being focused at the focal point of the first short axis homogenizer 410 and then be incident to the second short axis homogenizer 420.

[0111] The second short axis homogenizer 420 can be a cylindrical lens array having a planar incident surface and an emission surface convex in the third direction DR3. The second short axis homogenizer 420 can diffuse the beams separated by the refraction of the first short axis homogenizer 410 in the second direction (short axis direction) DR2.

[0112] A third short-axis homogenizer 430 can be disposed on the back surface of the second short-axis homogenizer 420. The third short-axis homogenizer 430 can be a convex lens having a plane as an entrance surface and a convex surface along the third direction DR3 as an exit surface. The third short-axis homogenizer 430 can refract the light beam combined and diffused in the second direction (short-axis direction) DR2 by the second short-axis homogenizer 420, thereby emitting the fourth laser beam LB4 in parallel along the third direction DR3. The fourth laser beam LB4 emitted from the third short-axis homogenizer 430 can have a uniform energy density in the second direction (short-axis direction) DR2. The short-axis dimension Dy4 of the fourth laser beam LB4 can be substantially the same as the short-axis dimension Dy3 of the third laser beam LB3, but is not limited thereto.

[0113] The fourth laser beam LB4 passing through the third short-axis homogenizer 430 can form a focal point at the first sub-focal plane OS1. The fourth laser beam LB4 incident to the first sub-focal plane OS1 can be irradiated at different angles of incidence from each other depending on the position of emission from the third short-axis homogenizer 430. The difference between the maximum angles of incidence of the fourth laser beam LB4 incident with reference to one point of the first sub-focal plane OS1 can be represented as a first divergence angle θ1. The first divergence angle θ1 can represent the difference between the maximum angles of incidence of the fourth laser beam LB4 in the case where the fourth laser beam LB4 passing through the third short-axis homogenizer 430 is irradiated to the first sub-focal plane OS1.

[0114] As a comparative example, in the case where the first laser beam LB1 is expanded in the second direction (short-axis direction) DR2 by the telescope lens portion 200 without using the beam quality factor conversion portion 300 and passing through the short-axis homogenizer portion 400, a 4th laser beam LB4a can be output. The 4th laser beam LB4a output from the third short-axis homogenizer 430 can form a focal point at a second sub-focal plane OS2, which is closer than the first sub-focal plane OS1 to the third short-axis homogenizer 430. The fourth laser beam LB4 can be irradiated at an angle of a second divergence angle θ2 with reference to the first direction (long-axis direction) DR1.

[0115] If the emission conditions of the fourth laser beam LB4 are the same, the greater the interval distance between the third short-axis homogenizer 430 and the sub-focal plane OS1, OS2 at which the focal point of the fourth laser beam LB4 is formed, the smaller the divergence angles θ1, θ2 of the fourth laser beam LB4 can be. In the case where the divergence angles θ1, θ2 of the fourth laser beam LB4 are small, the deviation in the angle of incidence of the laser beam LB is small, and thus the depth of focus (DOF) is increased, and thus the crystalline quality of the amorphous silicon thin film 11 can become excellent.

[0116] Reference Figure 5 and Figure 11The fourth laser beam LB4 passing through the minor-axis homogenizer section 400 can be incident to the major-axis homogenizer section 500. The major-axis homogenizer section 500 can include a first major-axis homogenizer 510, a second major-axis homogenizer 520, and a third major-axis homogenizer 530. The major-axis homogenizer section 500 receives the fourth laser beam LB4 having a Gaussian distribution of energy density in the first direction (major-axis direction) DR1 and changes it to a fifth laser beam LB5 having a uniform energy density in the first direction (major-axis direction) DR1.

[0117] The first major-axis homogenizer 510 can be a cylindrical lens array having an incident surface convex in the opposite direction of the third direction DR3 and an emission surface in a planar structure. The cylindrical lens array can be a structure in which a plurality of cylindrical lenses formed in the first direction (major-axis direction) DR1 are continuously arranged. The cylindrical lens can include a spherical lens or an aspherical lens. The incident fourth laser beam LB4 can be incident to the first major-axis homogenizer 510 and refracted by each cylindrical lens of the cylindrical lens array, and then divided into a plurality of beams.

[0118] The second major-axis homogenizer 520 can be arranged at the back of the first major-axis homogenizer 510. The second major-axis homogenizer 520 can be a cylindrical lens array having an incident surface in a planar structure and an emission surface convex in the third direction DR3. The focal length of the first major-axis homogenizer 510 can be shorter than the interval distance between the first major-axis homogenizer 510 and the second major-axis homogenizer 520. Each beam divided by the first major-axis homogenizer 510 can be dispersed again after being focused at the focal point of the first major-axis homogenizer 510 and then incident to the second major-axis homogenizer 520.

[0119] The third major-axis homogenizer 530 can be arranged at the back of the second major-axis homogenizer 520. The third major-axis homogenizer 530 can be a cylindrical lens having an incident surface in a planar structure and an emission surface convex in the third direction DR3. The third major-axis homogenizer 530 can refract the beams diffused in the first direction (major-axis direction) DR1 to the first direction (major-axis direction) DR1 and emit them as parallel fifth laser beams LB5. The fifth laser beam LB5 emitted from the third major-axis homogenizer 530 can have a uniform energy density in the first direction (major-axis direction) DR1. The fifth laser beam LB5 passing through the third major-axis homogenizer 530 can form a focal point at the first focal plane IS1. The major-axis dimension Dx of the fifth laser beam LB5 at the first focal plane IS1 can be substantially the same as the major-axis dimension Dx4 of the fourth laser beam LB4. The surface of the amorphous silicon thin film 11 can be located at the first focal plane IS1. That is, the major-axis dimension Dx at the first sub-focal plane OS1 can be substantially the same as the major-axis dimension Dx of the laser beam LB formed on the amorphous silicon thin film 11.

[0120] Referring to Figure 5 and Figure 12The fifth laser beam LB5 that passes through the first sub-focal plane OS1 can be incident to the projection lens portion 600. The fifth laser beam LB5 can be substantially the same as the fourth laser beam LB4 described above with reference to FIG. 6. The projection lens portion 600 can receive the fifth laser beam LB5 and emit a sixth laser beam LB6 having a reduced short axis dimension Dy from the first focal plane IS1. The short axis dimension Dy of the sixth laser beam LB6 at the first focal plane IS1 can be smaller than the short axis dimension Dy4 of the fifth laser beam LB5 at the first sub-focal plane OS1. The surface of the amorphous silicon thin film 11 can be located at the first focal plane IS1. That is, the short axis dimension Dy at the first sub-focal plane OS1 can be substantially the same as the short axis dimension Dy of the laser beam LB formed on the amorphous silicon thin film 11. Figure 10 The fifth laser beam LB5 that passes through the first sub-focal plane OS1 can be incident to the projection lens portion 600. The fifth laser beam LB5 can be substantially the same as the fourth laser beam LB4 described above with reference to FIG. 6. The projection lens portion 600 can receive the fifth laser beam LB5 and emit a sixth laser beam LB6 having a reduced short axis dimension Dy from the first focal plane IS1. The short axis dimension Dy of the sixth laser beam LB6 at the first focal plane IS1 can be smaller than the short axis dimension Dy4 of the fifth laser beam LB5 at the first sub-focal plane OS1. The surface of the amorphous silicon thin film 11 can be located at the first focal plane IS1. That is, the short axis dimension Dy at the first sub-focal plane OS1 can be substantially the same as the short axis dimension Dy of the laser beam LB formed on the amorphous silicon thin film 11.

[0121] The projection lens portion 600 can be a cylindrical lens that is convex in the third direction DR3 with respect to the incident surface and the emission surface, but is not limited thereto. The fifth laser beam LB5 incident to the projection lens portion 600 can be refracted by the projection lens portion 600 and emitted, thereby forming a focal point at the first focal plane IS1.

[0122] The fifth laser beam LB5 can have a third divergence angle θ3 and be incident to the projection lens portion 600 from the first sub-focal plane OS1. The sixth laser beam LB6 emitted from the projection lens portion 600 can have a fifth divergence angle θ5 and be incident to the first focal plane IS1.

[0123] A focal depth DOF1 can be formed at the first focal plane IS1. The focal depth DOF1 can be inversely proportional to the size of the fifth divergence angle θ5. As described above, the focal depth DOF1 indicates a distance that is considered to be in focus even if moving away from or closer to the first focal plane IS1 from the first focal plane IS1. That is, a substantially uniform energy can be provided from the first focal plane IS1 to a region located within the focal depth DOF1 of the laser beam LB.

[0124] As a comparative example, a case in which a fifth laser beam LB5a that passes through the second sub-focal plane OS2 is incident to the projection lens portion 600 is described. The fifth laser beam LB5a can be substantially the same as the fourth laser beam LB4a described above with reference to FIG. 7. The fifth laser beam LB5a can have a fourth divergence angle θ4 and be incident to the projection lens portion 600 from the second sub-focal plane OS2. The sixth laser beam LB6a emitted from the projection lens portion 600 can have a sixth divergence angle θ6 and be incident to the second focal plane IS2. Figure 10

[0125] ​A focal depth DOF2 can be formed at the second focal plane IS2. The focal depth DOF2 can be inversely proportional to the size of the sixth divergence angle θ6. As described above, the focal depth DOF2 represents a distance that is considered to be in focus even if moving away from or closer to the second focal plane IS2. That is, a region from the second focal plane IS2 to within the focal depth DOF2 of the laser beam LB can provide substantially uniform energy.

[0126] The sixth divergence angle θ6 can have a value smaller than the fifth divergence angle θ5. Therefore, the focal depth DOF2 of the 6a laser beam LB6a can be smaller than the focal depth DOF1 of the sixth laser beam LB6.

[0127] That is, the laser device LD using both the beam quality factor converting section 300 and the short axis homogenizer section 400 according to an embodiment can emit a laser beam LB having a larger focal depth than the laser device LD using only the short axis homogenizer section 400. Therefore, it is possible to provide uniform energy per region of the amorphous silicon thin film 11 and to uniformly achieve crystallization.

[0128] Figure 13 is a graph of an energy profile of a laser beam of a laser device according to a comparative embodiment. Figure 14 and Figure 15 is a graph of an energy profile of a laser beam of a laser device according to a comparative embodiment.

[0129] Figure 13 to Figure 15 is a graph showing the energy exhibited when the short axis dimension of a laser beam LB emitted from a laser device LD according to an embodiment is reduced to a level of about 100 μm, defocused at a focal plane, and measured at a distance farther than the focal plane and a distance closer than the focal plane, respectively. Figure 13 is a result regarding an energy profile of a laser beam LB emitted by a laser device LD using both a beam quality factor converting section 300 and a short axis homogenizer section 400 as the laser device LD according to an embodiment. Figure 14 is a result regarding a laser beam LB emitted from a laser device omitting the beam quality factor converting section 300 and using only the short axis homogenizer section 400, Figure 15 is a result regarding a laser beam LB emitted from a laser device omitting the short axis homogenizer section 400 and using only the beam quality factor converting section 300.

[0130] Referring to Figure 13 to Figure 15 It can be confirmed that, in the case where the short axis dimension is reduced to a level of about 100 μm, a laser beam LB emitted by a laser device LD according to an embodiment forms a flat top energy profile exhibiting uniform energy in the short axis direction.

[0131] It can be confirmed that, for the laser beam LB emitted from the laser device using only the short-axis homogenizer section 400 by omitting the beam quality factor conversion section 300, in the case where the short-axis dimension is reduced to the level of about 100 μm, the focal point depth is smaller than the laser beam LB emitted by the laser device LD according to an embodiment, and when defocusing, a flat top energy characteristic curve is not formed.

[0132] Therefore, when crystallizing the amorphous silicon thin film 11 using the laser device LD according to an embodiment at the level of the short-axis dimension of about 100 μm, compared to the case of crystallizing the amorphous silicon thin film 11 using the laser device using only the short-axis homogenizer section 400, uniform crystallization can be achieved in each region.

[0133] For the laser beam LB emitted from the laser device using only the beam quality factor conversion section 300 by omitting the short-axis homogenizer section 400, in the case where the short-axis dimension is reduced to the level of about 100 μm, the focal point depth can be larger than the laser beam LB emitted by the laser device using only the short-axis homogenizer section 400, and smaller than the laser beam LB emitted by the laser device LD according to an embodiment. Also, when defocusing, the change in energy intensity can be larger than Figure 13 the case of

[0134] Therefore, when crystallizing the amorphous silicon thin film 11 using the laser device LD according to an embodiment at the level of the short-axis dimension of about 100 μm, compared to the case of crystallizing the amorphous silicon thin film 11 using the laser device using only the beam quality factor conversion section 300, uniform crystallization can be achieved in each region.

[0135] Based on the laser device LD according to an embodiment, a narrower short-axis dimension Dy can be formed with a higher energy density, and a sufficient focal point depth is ensured, thereby providing a laser beam LB having uniform energy in each region in the short-axis direction.

[0136] Figure 16 is a flowchart showing a manufacturing method of a display device according to an embodiment.

[0137] Referring to Figure 16 , the manufacturing method of a display device according to an embodiment can include a step of preparing an object substrate on which an amorphous semiconductor layer is disposed (S100), and a step of irradiating a laser beam to the amorphous semiconductor layer to crystallize the amorphous semiconductor layer (S200). Here, the amorphous semiconductor layer can represent Figure 3 and Figure 4 the amorphous silicon thin film 11 shown in

[0138] The step of crystallizing the amorphous semiconductor layer by irradiating a laser beam to the amorphous semiconductor layer (S200) is the same as the process of irradiating a laser beam LB to the amorphous silicon thin film 11 by using the laser device LD according to an embodiment described above. Figure 3 to Figure 12 The process of irradiating a laser beam LB to the amorphous silicon thin film 11 by using the laser device LD according to an embodiment is the same as described above.

[0139] The above has been described centering on the embodiments of the present application, but this is merely an example, and the purpose is not to limit the present application, and it is known to those having ordinary knowledge in the field to which the present application pertains that various modifications and applications not exemplified above can be made within the scope of the essential characteristics of the embodiments of the present application. For example, each of the constituent elements specifically appearing in the embodiments of the present application can be modified and implemented. Also, the differences with respect to these modifications and applications should be interpreted as being included in the scope of the present application defined in the claims.

Claims

1. A laser device comprising: a laser module that emits a laser beam; a first optical system that expands the laser beam emitted from the laser module in a first direction intersecting with an emission direction and emits it; a second optical system that causes a plurality of sub-beams that split the laser beam emitted from the first optical system in the first direction to be arranged in a second direction intersecting with the emission direction and the first direction and emits them; a third optical system that homogenizes the energy of the laser beam emitted from the second optical system in the first direction; and a fourth optical system that reduces the size of the laser beam emitted from the third optical system in the first direction, wherein the third optical system includes: a first short-axis homogenizer including a cylindrical lens array whose incident surface is convex in the opposite direction of the emission direction and whose emission surface is a flat structure; a second short-axis homogenizer disposed on the side of the first short-axis homogenizer toward the emission surface and including a cylindrical lens array whose incident surface is a flat structure and whose emission surface is convex in the emission direction; a third short-axis homogenizer disposed on the side of the second short-axis homogenizer toward the emission surface and including a lens whose incident surface is a flat structure and whose emission surface is convex in the emission direction, wherein the laser beam that has passed through the third short-axis homogenizer forms a focal point on a first sub-focal plane, in a case where the laser beam is caused to pass through the third optical system without using the second optical system and only with the first optical system so as to be expanded in the second direction, the output laser beam forms a focal point on a second sub-focal plane that is closer to the third short-axis homogenizer than the first sub-focal plane.

2. The laser device according to claim 1, wherein the second optical system causes the size of the laser beam in the first direction and the size in the second direction to be exchanged with each other and emits them.

3. The laser device according to claim 2, wherein the second optical system maintains the beam quality factor of the laser beam in the first direction and the second direction and causes the sizes in the first direction and the second direction to be exchanged with each other. further comprising:

4. The laser device of claim 1, wherein, a fifth optical system that homogenizes the energy of the laser beam in the second direction.

5. The laser device according to claim 4, wherein the fifth optical system includes: a first long-axis homogenizer including a cylindrical lens array whose incident surface is convex in the opposite direction of the emission direction and whose emission surface is a flat structure; a second long-axis homogenizer disposed on the side of the first long-axis homogenizer toward the emission surface and including a cylindrical lens array whose incident surface is a flat structure and whose emission surface is convex in the emission direction; a third long-axis homogenizer disposed on the side of the second long-axis homogenizer toward the emission surface and including a lens whose incident surface is a flat structure and whose emission surface is convex in the emission direction.

6. The laser device according to claim 4, wherein the laser beam that has passed through the second optical system is incident to the fifth optical system. ​ 7. The laser device according to claim 1, wherein the fourth optical system includes a cylindrical convex lens which extends in the second direction and whose entrance face is convexed in a direction opposite to the emission direction.

8. The laser device according to claim 7, wherein the laser beam emitted from the fourth optical system forms a focal point on an upper surface of an object substrate.

9. The laser device according to claim 1, wherein the laser beam before passing through the first optical system maintains a beam quality factor with respect to the second direction and reduces a beam quality factor with respect to the first direction.

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