Device for laser irradiation

Abstract

An apparatus for laser irradiation includes a laser module configured to emit a laser beam, a first optical system configured to scan the laser beam emitted from the laser module in a first direction, an optical element configured to refract the laser beam emitted from the first optical system, and a substrate support on which a base substrate to which the laser beam refracted through the optical element reaches is disposed.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority and benefit to Korean Patent Application No. 10-2019-0143312, filed with the Korean Intellectual Property Office on November 11, 2019, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] Some aspects of exemplary embodiments of this disclosure relate to laser irradiation apparatuses. Background Technology

[0004] The pixel driving circuitry of a display device may include thin-film transistors (TFTs) using silicon. Amorphous silicon or polycrystalline silicon can be used as the silicon constituting the TFT.

[0005] Since the semiconductor active layer forming the source, drain, and channel can be amorphous silicon, the amorphous silicon thin-film transistors (a-Si TFTs) used in pixel driving circuits can have a 1cm diameter. 2 Amorphous silicon thin-film transistors (TFTs) have a relatively low electron mobility of / Vs or lower. Therefore, they can be replaced by polycrystalline silicon TFTs (polycrystalline silicon TFTs). Polycrystalline silicon TFTs can have relatively higher electron mobility and relatively better light irradiation stability than amorphous silicon TFTs. Therefore, polycrystalline silicon is suitable as the active layer for driving TFTs or switching TFTs in display devices.

[0006] Polycrystalline silicon can be manufactured by various methods, including methods of directly depositing polycrystalline silicon and methods of depositing amorphous silicon and then crystallizing it. In the method of depositing amorphous silicon and then crystallizing it, the amorphous silicon thin film can be crystallized by methods such as laser beam irradiation or heating. The laser irradiation device can use an optical module to convert the laser beam into a surface beam, and then crystallize the amorphous silicon thin film on the substrate by irradiating it with the surface beam.

[0007] The information disclosed in this background section is only intended to enhance the understanding of the background art, and therefore, the information discussed in this background section does not necessarily constitute prior art. Summary of the Invention

[0008] When a laser beam has anomalies or defects due to problems such as lens contamination or cracks in the laser irradiation device, crystalline anomalous portions or regions with different grain sizes may appear, for example, as stripes or lines, depending on the laser scan. In a display device, crystalline anomalous portions can be identified or perceived by the user as stripes or lines in the final manufactured product.

[0009] Some exemplary embodiments of this disclosure are intended to provide a laser irradiation apparatus for manufacturing a display device having relatively uniform quality.

[0010] According to some example embodiments, a laser irradiation device includes: a laser module configured to emit a laser beam; a first optical system configured to scan the laser beam emitted from the laser module in one direction; an optical element configured to refract the laser beam emitted from the first optical system; and a substrate support thereon having a substrate to which the laser beam refracted by the optical element reaches.

[0011] Some exemplary embodiments of this disclosure are not limited to the features described above, and those skilled in the art can more clearly understand other features not mentioned based on the specification and drawings.

[0012] According to some example embodiments of this disclosure, a laser irradiation apparatus can be provided for providing relatively uniform crystal quality.

[0013] The features of the exemplary embodiments disclosed herein are not limited to those described above, and many more features are included in the specification. Attached Figure Description

[0014] The above and other aspects and features of the exemplary embodiments of this disclosure will become more apparent from certain characteristics as described in more detail with reference to the accompanying drawings, wherein:

[0015] Figure 1 This is a configuration diagram of a laser irradiation apparatus according to some example embodiments;

[0016] Figure 2 It is along Figure 1 A cross-sectional view of the laser irradiation device taken from line II-II' in the diagram;

[0017] Figure 3 It is along Figure 1 A cross-sectional view of the laser irradiation device taken from line III-III' in the diagram;

[0018] Figure 4 This is a waveform diagram of the laser beam emitted from the laser module;

[0019] Figure 5 It is a schematic diagram used to describe a laser irradiation process according to some example embodiments;

[0020] Figure 6 This is a plan view of the laser spot and scan line during laser irradiation according to some example embodiments;

[0021] Figure 7 This is a schematic diagram illustrating the laser irradiation process performed when the optical element is tilted;

[0022] Figure 8 yes Figure 7 An enlarged cross-sectional view of region A shown in the figure;

[0023] Figure 9 This is a planar diagram illustrating the scan lines formed by the laser beam during laser irradiation.

[0024] Figure 10 This is a schematic diagram illustrating the change in crystal width during laser beam scanning in the laser irradiation process, when the tilt angle of the optical element changes and the scanning direction is the same as the horizontal movement direction.

[0025] Figure 11 This is a schematic diagram illustrating the change in crystal width during laser beam scanning in the laser irradiation process, when the tilt angle of the optical element changes and the scanning direction is opposite to the horizontal movement direction.

[0026] Figure 12 This is a schematic diagram of a laser irradiation device with cracks.

[0027] Figure 13 The diagram is based on Figure 12 A plan view of the substrate shown in a laser irradiation device when the tilt angle of the optical element does not change;

[0028] Figure 14 The diagram is based on Figure 12 A plan view of the substrate shown in the laser irradiation device when the tilt angle of the optical element changes; and

[0029] Figure 15 This is a schematic diagram of a laser irradiation apparatus according to some example embodiments. Detailed Implementation

[0030] Some aspects of the invention will now be described more fully below with reference to the accompanying drawings, in which some exemplary embodiments of the invention are illustrated. However, the invention may be implemented in various forms and should not be construed as limited to the exemplary embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be more thorough and complete, and will more fully convey the scope of the invention to those skilled in the art.

[0031] It should also be understood that when a layer is referred to as being "on" another layer or substrate, it can be directly on the other layer or substrate, or there can be an intermediate layer. Conversely, when an element is referred to as being "directly" on another element, there is no intermediate element.

[0032] For ease of description, spatial relative terms such as “below,” “under,” “down,” “above,” and “up” are used herein to describe the relationship between one element or feature illustrated in the accompanying drawings and another element or feature. It will be understood that, in addition to the orientation depicted in the drawings, spatial relative terms are intended to also include different orientations of the device in use or operation. For example, if the device in the drawings is flipped, an element described as “below” or “under” other elements or features will be oriented “above” other elements or features. Thus, the example term “below” can include both above and below orientations. The device may be otherwise oriented (rotated 90 degrees or in other orientations), and the spatial relative descriptors used herein should be interpreted accordingly.

[0033] Throughout the specification, the same reference numerals denote the same parts.

[0034] Figure 1 This is a configuration diagram of a laser irradiation device according to some example embodiments. Figure 2 It is along Figure 1 The cross-sectional view of the laser irradiation device taken from line II-II' in the figure. Figure 3 It is along Figure 1 The cross-sectional view of the laser irradiation device taken from line III-III' in the figure. Figure 4 This is a waveform diagram of the laser beam emitted from the laser module.

[0035] refer to Figures 1 to 4 According to some example embodiments, the laser irradiation apparatus 100 may be able to crystallize an amorphous thin film on a substrate 10 by irradiating it with a laser. In the following, although an example of amorphous silicon thin film deposited on substrate 10 being crystallized into crystalline silicon thin film is illustrated, the embodiments according to this disclosure are not limited thereto.

[0036] The substrate 10 can be configured as a planar substrate, for example, for use in a display device. Organic light-emitting display devices, micro-LED display devices, nano-LED display devices, quantum dot light-emitting display devices, liquid crystal display devices, plasma display devices, field emission display devices, electrophoretic display devices, or electrowetting display devices are examples of display devices, but the embodiments are not limited thereto.

[0037] The substrate 10 can be a glass substrate or a flexible substrate. The flexible substrate can be one of polyethylene terephthalate (PET) film, polypropylene (PP) film, polyethylene (PE) film, polyimide (PI) film, polystyrene (PS) film, polycarbonate (PC) film, polyethylene naphthalate (PEN) film, cyclic olefin copolymer (COC) film, and acrylic film.

[0038] At least one or more element regions 10a may be formed in the upper surface of the substrate 10. An amorphous silicon thin film may be deposited on the element regions 10a. The element regions 10a may be formed by sub-element regions that are divided into smaller regions.

[0039] In the element region 10a, the amorphous silicon thin film, after crystallization, can be used to fabricate various components required for the operation of a flat panel display device. Simultaneously, the amorphous silicon thin film deposited on the substrate 10 can be integrally formed as the element region 10a without being divided by it. The substrate 10 and the various components formed in the element region 10a can form a planar substrate for the display device.

[0040] The configuration of the laser irradiation device 100 will be described in more detail below.

[0041] According to some example embodiments, the laser irradiation device 100 may include a substrate support 120, a first optical system 130, an optical element 140, and a laser module 150.

[0042] The laser irradiation apparatus 100 may further include a hollow processing chamber, and a heat treatment atmosphere and / or a vacuum atmosphere may be formed. The processing chamber may be a space in which the laser irradiation process is carried out.

[0043] The substrate support 120, the first optical system 130, and the optical element 140 may be located within the processing chamber. The laser module 150, connected to the first optical system 130, may be located outside the processing chamber. The processing chamber may be formed in a cuboid shape, but the embodiments are not limited to this, and the processing chamber may have various shapes. The processing chamber may be connected to a heater to create a heat treatment atmosphere and may be connected to a vacuum module to create a vacuum atmosphere.

[0044] The substrate 10, which will be subjected to laser irradiation, can be placed on a substrate support 120. The substrate support 120 can be a support for the substrate 10 on which a silicon thin film is formed. The substrate support 120 can have an area larger than that of the substrate 10. The edge of the substrate 10 can be located within a region of the substrate support 120. The substrate 10 typically occupies the center of the substrate support 120. The substrate support 120 can have a basic cuboid shape, but the embodiments are not limited to this, and the substrate support 120 can have a cubic shape, a polygonal column shape, or a cylindrical shape, etc.

[0045] A separate conveying unit can move the substrate support 120. For example, a roller can move the substrate support 120, but the embodiments are not limited thereto. The substrate support 120 can be secured to the substrate 10 mounted on its upper surface using a clamping unit. The clamping unit can secure the substrate 10 using vacuum, electrostatics, and / or van der Waals forces.

[0046] The first optical system 130 may be a device for telecentrically scanning a laser beam emitted from the laser module 150, which will be described later. For example, the first optical system 130 may be connected to the laser module 150 and may scan the laser beam transmitted from the laser module 150 on the upper or lower surface of the substrate 10 to form a scan line SL (see [link to documentation]). Figure 6 The scan line SL can refer to a line formed on the upper surface of the substrate 10 when the first optical system 130 scans the laser beam overlappingly from one side of the substrate 10 to the other.

[0047] The first optical system 130 can be rotatably configured and may include a polygonal mirror 131 having a polygonal cylindrical shape, a convex mirror 133 spaced apart from the other side of the polygonal mirror 131 in the second direction DR2 and from the other side of the polygonal mirror 131 in the third direction DR3, and a concave mirror 135 spaced apart from one side of the convex mirror 133 in the third direction DR3. Hereinafter, as an example of the first optical system 130, a first optical system 130 including a polygonal mirror 131, a convex mirror 133, and a concave mirror 135 is illustrated, but the embodiments are not limited thereto. For example, the first optical system 130 may include a galvanometer and a planar focusing (f-theta) lens. Here, the galvanometer may replace the polygonal mirror 131, and the f-theta lens may replace the convex mirror 133 and the concave mirror 135.

[0048] According to some example embodiments, although in Figure 2 A polygonal mirror 131 with an octagonal prism shape is shown, but embodiments according to this disclosure are not limited thereto, and the polygonal mirror 131 can be configured with another polygonal shape, such as a nonagonal prism or a decagonal prism. The polygonal mirror 131 can be configured to be connected to an external drive source for rotatability.

[0049] The convex mirror 133 can be configured such that its convex surface faces one side of the third direction DR3, and its flat surface faces the other side of the third direction DR3. The concave mirror 135 can be configured such that its concave surface faces the other side of the third direction DR3, and its flat surface faces one side of the third direction DR3. Compared to the convex mirror 133, the concave mirror 135 can have a larger width in the first direction DR1. The positional relationship between the polygon mirror 131, the convex mirror 133, and the concave mirror 135 is not limited to the above, and the polygon mirror 131, the convex mirror 133, and the concave mirror 135 can have other positional relationships, as long as the same movement path as the laser beam movement path, which will be described in more detail below, is shown.

[0050] The laser beam emitted to the first optical system 130 can be directed onto the polygon mirror 131. The laser beam directed onto the polygon mirror 131 can be reflected by the polygon mirror 131 and then directed onto the convex mirror 133. The laser beam directed onto the convex mirror 133 can be reflected by the convex mirror 133 and then directed onto the concave mirror 135. The laser beam directed onto the concave mirror 135 can be reflected by the concave mirror 135 and then directed onto the substrate 10.

[0051] When a laser beam is irradiated onto the first optical system 130, the faceted mirror 131 can rotate. As the faceted mirror 131 rotates, the laser beam can scan the upper surface of the convex mirror 133 from one side to the other along the first direction DR1. The laser beam reflected by the convex mirror 133 can scan the lower surface of the concave mirror 135 from one side to the other along the first direction DR1. The laser beam reflected by the concave mirror 135 can scan the upper surface of the substrate 10 from one side to the other along the first direction DR1.

[0052] The first optical system 130 can be positioned on the third-direction DR3, spaced apart from one side of the substrate 10 mounted on the substrate support 120, but may be disposed on the other side of the substrate 10 on the third-direction DR3, depending on the structure of the substrate support 120. The first optical system 130 may overlap with the substrate support 120 on the third-direction DR3. The other surface of the first optical system 130 on the third-direction DR3 may be formed as an open surface, but the embodiments are not limited thereto; it may consist of a flat plate formed of a transparent material that has little effect on the laser beam.

[0053] As described above, since the first optical system 130 scans the laser beam in a telecentric manner over the entire region of the scan line SL, a laser spot 20 is formed along the scan line SL (e.g., in...). Figure 6 (As shown) can be formed uniformly. That is, the shape and size of the laser spot 20 can be formed uniformly, regardless of its position in the scan line SL.

[0054] In the laser irradiation apparatus 100 according to some example embodiments, the laser beam can be scanned while the substrate 10 moves along the second direction DR2 and the first optical system 130 is in a fixed state. However, the embodiments according to this disclosure are not limited to this, and the laser beam can be scanned while the first optical system 130 moves along the second direction DR2 and the substrate 10 is in a fixed state.

[0055] The scan line SL can be formed by a method in which a first optical system 130 scans a laser beam from one side of the substrate 10 in a first direction DR1 to the other side, and then, after the substrate 10 moves a distance (e.g., a set or predetermined distance) towards one side in a second direction DR2, the laser beam scan from one side of the substrate 10 in the first direction DR1 to the other side is repeated.

[0056] The first optical system 130 does not need to move along the first direction DR1 that forms the scan line SL. Therefore, the scan line SL can be formed as a uniform straight line along the first direction DR1. That is, the laser spot 20 forming the scan line SL can have a uniform overlap area with adjacent laser spots 20, such that the distance or interval between portions (e.g., central portions) of adjacent laser spots 20 is uniform or relatively uniform across the scan line SL. Therefore, the heating temperature of the thin film can be maintained relatively uniformly. In other words, in the laser irradiation apparatus 100, since the first optical system 130 does not need to move along the first direction DR1, the linearity of the scan line SL can be improved throughout the entire area of ​​the substrate 10, thereby improving the uniformity of the heating temperature.

[0057] The first optical system 130 can appropriately adjust the scanning speed and spot spacing according to the diameter of the laser spot 20 to adjust the heating temperature of the amorphous silicon thin film. For example, the first optical system 130 can increase the overlap area between two adjacent laser spots 20 in the scan line SL by reducing the scanning speed, thereby increasing the heating temperature of the amorphous silicon thin film.

[0058] When a laser beam irradiating from the first optical system 130 toward the substrate 10 is perpendicular to the substrate 10, the laser beam reflected back to the substrate 10 may damage the first optical system 130. Therefore, the first optical system 130 can irradiate a laser beam tilted at a predetermined angle relative to the axis on the third-party direction DR3. For this purpose, the first optical system 130 itself can be tilted relative to the axis on the third-party direction DR3, but is not limited to this; it can be parallel to the axis on the third-party direction DR3, and only the laser beam can be tilted.

[0059] An optical element 140 may be disposed between the first optical system 130 and the substrate 10. The optical element 140 may be a flat plate through which the laser beam emitted from the first optical system 130 passes and is refracted before reaching the substrate 10. The optical element 140 may be positioned spaced apart from the other side of the first optical system 130 on the third-direction DR3, and also spaced apart from one side of the substrate 10 on the third-direction DR3. The optical element 140 may overlap with the first optical system 130 on the third-direction DR3, and may also overlap with the substrate support 120 on the third-direction DR3.

[0060] The optical element 140, positioned horizontally and without tilt, can be substantially parallel to the substrate support 120 and perpendicular to the laser beam. The optical element 140 can be connected to a rotating rod 141 perpendicular to the laser beam. The rotating rod 141 can be connected to the central portion of the side surface of the optical element 140.

[0061] Optical element 140 can be rotated and tilted via a rotating rod 141 connected thereto. The tilt angle, which is the angular difference between the horizontal optical element 140 and the tilted optical element 140 and indicates the tilt degree of the optical element 140, can be changed by rotating the rotating rod 141. According to some example embodiments, the rotating rod 141 can be connected to a rotating module 142 to change the tilt angle of the optical element 140 via the rotating module 142.

[0062] For example, the tilt angle can be changed in such a way that, by rotating the rotating rod 141, the optical element 140 tilts from a horizontal state in one direction at an angle (e.g., a set or predetermined angle) and then returns to a horizontal state, and tilts in another direction at the same angle as the aforementioned angle and then returns to a horizontal state.

[0063] Optical element 140 may be formed of a material having a refractive index (n) in the range of 1.3 to 2.0 and capable of allowing a laser beam to pass through it. That is, the refractive index of optical element 140 may be between 1.3 and 2.0. When the refractive index (n) is less than 1.3, the refractive effect may be small, and when the refractive index (n) is greater than 2.0, the transmittance of a laser beam with a wavelength of 350 nm or less may be low. According to some example embodiments, optical element 140 may be formed of a material selected from magnesium fluoride, calcium fluoride, yttrium aluminum garnet, quartz, and sapphire, or a combination thereof. The refractive index of magnesium fluoride may be approximately 1.39, the refractive index of calcium fluoride may be approximately 1.40, the refractive index of yttrium aluminum garnet may be approximately 1.82, the refractive index of quartz may be approximately 1.54, and the refractive index of sapphire may be approximately 1.76.

[0064] If a rotating mirror that reflects the laser beam is used instead of optical element 140, the angle of the scan lines SL of the laser beam can change depending on the angle of the rotating mirror and may not be parallel to each other. On the other hand, the laser irradiation apparatus 100 according to some example embodiments can use optical element 140 that transmits the laser beam. The tilt angle of optical element 140 can be changed by the rotation axis of a rotating rod 141 that is parallel to the substrate support 120 and perpendicular to the scan lines SL. Therefore, the parallelism of the scan lines SL can be maintained regardless of the tilt angle of optical element 140.

[0065] A laser beam that can illuminate the substrate 10 can be emitted from the laser module 150. The laser module 150 can be located outside the processing chamber and can be connected to the first optical system 130.

[0066] Laser module 150 may include a fiber laser that emits a laser beam in the infrared, visible, or ultraviolet bands. Laser module 150 may include an output optical fiber that transmits the laser beam to an external location. Because laser module 150 is connected to first optical system 130 via the output optical fiber and transmits the laser beam, laser beam loss can be minimized during transmission. The fiber laser may include a laser diode optically pumped therefrom and a fiber Bragg grating used as a laser oscillator. The fiber laser can illuminate or emit a laser beam in the infrared, visible, or ultraviolet bands. In the case of the visible band, the fiber laser can emit a laser beam in the green band. According to some example embodiments, the fiber laser can emit and illuminate a laser beam with a wavelength of 532 nm. Furthermore, the fiber laser can emit and illuminate a laser beam in the ultraviolet band. The fiber laser can emit a laser beam of appropriate bands depending on the crystallization temperature and crystallization time of the thin film.

[0067] A fiber laser can be configured to have an appropriate frequency by adjusting the irradiation and pause times of the laser beam. For example, the laser beam of a fiber laser can be irradiated with a frequency of 10 to 200 MHz. Here, the frequency of the laser beam can be the number of times the laser beam is irradiated per unit time. Furthermore, the irradiation and pause times of the fiber laser can be adjusted in nanoseconds to adjust the number of irradiations and the applied energy of the laser beam irradiating a laser spot 20. The laser beam of a fiber laser is a pulsed laser with a peak value, but a laser beam with quasi-continuous wave characteristics can be irradiated by adjusting the irradiation and pause times. Therefore, the heating temperature of the thin film can be adjusted by changing the number of irradiations of the laser beam.

[0068] The fiber laser can be turned on and off for each laser spot 20, and the laser beam can be selectively irradiated for each location. Therefore, the fiber laser can perform selective thermal treatment on each tiny location of the thin film.

[0069] Fiber lasers can heat thin films to temperatures below their melting point. According to some example embodiments, fiber lasers can heat amorphous silicon thin films to temperatures below their melting point. When crystalline silicon thin films crystallize at temperatures below their melting point, crystallinity can be increased due to a reduction in anomalous protrusions forming at grain boundaries. Since the melting temperature of amorphous silicon thin films is approximately 1460°C, the fiber laser can be controlled to heat the amorphous silicon thin film to temperatures between 1300 and 1400°C.

[0070] Figure 5 This is a schematic diagram used to describe a laser irradiation process according to some example embodiments. Figure 6 It is a plan view of the laser spot and scan line during laser irradiation according to some example embodiments.

[0071] refer to Figure 5 and Figure 6 The process of irradiating an amorphous silicon thin film with a laser using a laser irradiation device 100 will be described. The laser irradiation device 100 can irradiate a substrate 10 with a laser beam to crystallize the amorphous silicon thin film into a crystalline silicon thin film. The laser module 150 can emit the laser beam to a first optical system 130. As described above, the laser beam can be sequentially reflected by a polygon mirror 131, a convex mirror 133, and a concave mirror 135 to irradiate the substrate 10. When the laser beam is irradiated onto the first optical system 130, with the polygon mirror 131 rotated R1, the laser beam can be scanned from one side of the first direction DR1 to the other (i.e., in the scanning direction SD of the laser beam) to form a scan line SL.

[0072] Overlapping regions can be formed between adjacent laser spots 20 along a scan line SL. Within the laser spots 20, the overlapping region and scanning speed can be varied depending on the laser beam frequency and the crystallization temperature. When the crystallization temperature is relatively high, the laser beam scanning speed can be reduced, increasing the overlapping region between adjacent laser spots 20. The amorphous silicon film can be heated to the crystallization temperature while increasing the number of irradiations at a single spot. Simultaneously, when the laser beam frequency is high, the amorphous silicon film can still be heated to the crystallization temperature even when the laser beam scanning speed increases and thus the overlapping region decreases.

[0073] The first optical system 130 can be located outside one side of the element region 10a in the second direction DR2 to illuminate the laser beam while forming scan lines SL. The side of the first scan line SL formed in the second direction DR2 may not overlap with the later scan lines SL formed, while the area overlapping with the later scan lines SL may appear on the other side of that scan line SL in the second direction DR2. Therefore, since there may be a temperature difference between the first scan line SL formed in the second direction DR2 and the other side, the first optical system 130 can be located outside one side of the element region 10a in the second direction DR2.

[0074] A first optical system 130 constituting a laser irradiation apparatus 100 according to one embodiment can scan a laser beam from one side to the other in a first direction DR1 of the element region 10a to form a scan line SL. After forming the scan line SL, the substrate 10 can be moved to one side in a second direction DR2 (e.g., moved a set or predetermined distance). The first optical system 130 can scan the laser beam from one side to the other in the first direction DR1 to form the scan line SL. In this case, the laser beam may not scan areas on the substrate 10 other than the element region 10a.

[0075] The laser spot 20 of the scan line SL can overlap with the laser spot 20 of the previously formed scan line SL. That is, the scan line SL can overlap with the previously formed scan line SL. However, since the number of times the laser beam irradiates the region where the laser spots 20 overlap each other along the second direction DR2 is increased compared with the number of times it irradiates the non-overlapping region, the heating temperature can be increased.

[0076] Furthermore, since the first optical system 130 scans the laser beam while uniformly forming scan lines SL from one side to the other of the element region 10a, the temperature on the side of the previous scan line SL will decrease after a certain period of time. Therefore, the temperature increase in the overlapping region of the laser spot 20 formed on one side of the scan line SL and the laser spot 20 formed on the previous scan line SL will not be too high. Furthermore, since the subsequent laser beam is sequentially irradiated after the same time elapsed as that for the previous laser spot 20, the temperature increase in the laser spot 20 formed while moving from one side to the other of the scan line SL is likely not significant compared to the temperature of adjacent laser spots 20 within the same scan line SL. Therefore, even when the scan lines SL overlap, the temperature increase in the overlapping region is likely not significant. Furthermore, the temperature difference in the overlapping region between the scan lines SL on one side and the other side of the scan line SL in the first direction DR1 is likely not significant.

[0077] On the other hand, when a scan line SL is formed from one side to the other on the first direction DR1, and the next scan line SL is formed from the other side to the same side on the first direction DR1, that is, when the scan line SL is formed in a zigzag shape, the temperature rise may be large because the laser beams overlap and irradiate the laser spot 20 formed on the other side of the scan line SL with relatively small time intervals. Conversely, the temperature rise may be small because the laser beams overlap and irradiate the laser spot 20 formed on one side of the scan line SL with relatively long time intervals. Therefore, the difference in temperature rise between the overlapping regions on one side and the other side of the first direction DR1 in the overlapping region between scan lines SL may be large.

[0078] The first optical system 130 can form a scan line SL with a length greater than the width of the element region 10a formed in the substrate 10. The first optical system 130 can irradiate a laser beam such that a laser spot 20 formed at one end of the scan line SL in the first direction DR1 can be formed on the outer side of one side of the element region 10a in the first direction DR1. According to some example embodiments, the first optical system 130 can allow multiple laser spots 20 formed at one end of the first direction DR1 to be formed on the outer side of one side of the element region 10a in the first direction DR1. Furthermore, the first optical system 130 can irradiate a laser beam such that a laser spot 20 formed at the other end of the scan line SL in the first direction DR1 can be formed on the outer side of the other side of the element region 10a in the first direction DR1. According to some example embodiments, the first optical system 130 can allow multiple laser spots 20 formed at the other end of the first direction DR1 to be formed on the outer side of the other side of the element region 10a in the first direction DR1. Due to differences in the number of times the laser beam is irradiated, the laser spot 20 formed at one end and the other end of the scan line SL in the first direction DR1 may be unstable compared to the laser spot 20 formed in the central region. Therefore, the first optical system 130 can irradiate the laser beam so that stable laser spots 20, other than those at one side and the other side of the scan line SL in the first direction DR1, can be formed in the element region 10a.

[0079] Figure 7 This is a schematic diagram illustrating the laser irradiation process performed when the optical element is tilted. Figure 8 yes Figure 7 An enlarged cross-sectional view of region A shown in the figure. Figure 9 This is a planar diagram illustrating the scan lines formed by the laser beam during laser irradiation.

[0080] refer to Figures 7 to 9 This will describe the horizontal movement of the laser beam in the first direction DR1 when the tilt angle of the optical element 140 changes. (Refer to the above reference.) Figure 5 As described, the laser module 150 can emit a laser beam into the first optical system 130, and the laser beam can be sequentially reflected by a polygonal mirror 131, a convex mirror 133, and a concave mirror 135 to irradiate the substrate 10. Simultaneously, in embodiments where the first optical system 130 includes a current detector and an f-theta lens, the laser beam can be sequentially irradiated onto the substrate 10 through the current detector and the f-theta lens.

[0081] When the laser beam is emitted to the first optical system 130, with the polygon mirror 131 rotating R1, the laser beam can be scanned from one side of the first direction DR1 to the other side (i.e., in the scanning direction SD of the laser beam) to form a scan line SL.

[0082] In this case, when the optical element 140 rotates by R2 and thus the tilt angle is changed, the laser beam can be refracted by the optical element 140 tilted by the rotation of R2. When the laser beam is refracted, the laser spot 20 can move horizontally in the first direction DR1. Therefore, the scan line SL formed by the laser spot 20 can also move horizontally in the first direction DR1. The horizontal movement direction of the scan line SL can be the same as or opposite to the scan direction SD. In the following text, reference will be made to... Figure 7 A magnified view of region A shown in the image. Figure 8 Specifically, describe the horizontal movement of the scan line SL caused by the refraction of the laser beam.

[0083] When a laser beam propagating to an optical element 140 with a refractive index (n) and a thickness of t has an incident angle of α and a refraction angle of β, the refractive index (n) can be determined by... The length L of the propagation path of the laser beam in the optical element 140 can be represented by... The horizontal movement distance x of the laser beam in the first direction DR1 can be represented by x = L × sin(α - β). Therefore, since the angle β can be represented by... Therefore, the horizontal movement distance x of the laser spot 20 formed by the laser beam propagating at an incident angle α to an optical element 140 with a refractive index (n) and a thickness of t can be determined by... express.

[0084] Therefore, according to some example embodiments, the laser beam can pass through the optical element 140 and be irradiated onto the substrate 10. Compared to the case where the optical element 140 is horizontal, when the optical element 140 is tilted, the laser beam is refracted, and thus the laser spot 20 can move horizontally on the substrate 10 in the first direction DR1 by a length or distance (e.g., a set or predetermined length). Therefore, the scan line SL can move horizontally relative to its adjacent scan line SL in the first direction DR1 by a length or distance (e.g., a set or predetermined length), and thus alignment errors may occur. The horizontal movement distance x can vary depending on the refractive index (n) and thickness t of the optical element 140 and the incident angle α, and its magnitude depends on the above-described formula for the horizontal movement distance x.

[0085] When a scan line SL is formed and the tilt angle of the optical element 140 is changed before the formation of the next scan line SL, the scan line SL can be as follows: Figure 9 As shown in the figure. When assuming Figure 9 When one of the scan lines SL shown is a scan line SL formed when the horizontal optical element 140 is tilted α in one direction, the scan line SL adjacent to the aforementioned scan line SL in the second direction DR2 can be a scan line SL formed when the horizontal optical element 140 is tilted α in the opposite direction. Therefore, in Figure 9 The alignment error between adjacent scan lines SL formed in the first direction DR1 can be Figure 8 The horizontal movement distance x shown is twice that of the distance shown.

[0086] Even when the tilt angle of the optical element 140 is changed during the formation of the scan line SL, the parallelism of the scan line SL can be maintained. As described above, since the tilt angle of the optical element 140 is changed by the rotation axis of the rotating rod 141, which is parallel to the substrate support 120 and perpendicular to the scan line SL, the parallelism of the scan line SL can be maintained.

[0087] Figure 10 This diagram illustrates the change in crystal width during laser beam scanning in a laser irradiation process, when the tilt angle of the optical element changes and the scanning direction is the same as the horizontal movement direction. Figure 11 This is a schematic diagram illustrating the change in crystal width during laser beam scanning in the laser irradiation process, when the tilt angle of the optical element changes and the scanning direction is opposite to the horizontal movement direction.

[0088] refer to Figure 10 and Figure 11 When more laser beams are irradiated onto the amorphous silicon thin film, more crystals can occur in the corresponding parts of the silicon thin film, and the width of the crystallized region can increase.

[0089] In the laser irradiation apparatus 100 according to some example embodiments, the tilt angle of the optical element 140 can be changed during laser beam scanning. When the tilt angle of the optical element 140 is changed during laser beam scanning, and the scanning direction SD and the horizontal movement direction MD1 of the laser beam are the same, the scanning speed can be relatively increased due to the refraction of the laser beam that occurs simultaneously with the laser beam passing through the optical element 140. A fast laser beam scanning speed can refer to a situation where the irradiation time of the laser beam on a specific region of the amorphous silicon thin film is short, and therefore the irradiation amount of the laser beam is small. Therefore, when the tilt angle of the optical element 140 is changed so that the laser beam moves horizontally in the same direction as the scanning direction SD, the width W1 of the crystalline region can be reduced simultaneously with the change of the tilt angle of the optical element 140 compared to the case where the tilt angle of the optical element 140 is not changed.

[0090] When the tilt angle of the optical element 140 is changed during laser beam scanning, and the scanning direction SD and the horizontal movement direction MD2 of the laser beam are opposite, the scanning speed can be relatively slow due to the refraction of the laser beam that occurs simultaneously with the passing of the optical element 140. A slow laser beam scanning speed can refer to a situation where the laser beam irradiates a specific region of the amorphous silicon thin film for a long time, and therefore the irradiation amount is large. Therefore, when the tilt angle of the optical element 140 is changed so that the laser beam moves horizontally in a direction opposite to the scanning direction SD, the width W2 of the crystalline region can increase simultaneously with the change of the tilt angle of the optical element 140, compared to the case where the tilt angle of the optical element 140 remains unchanged.

[0091] Figure 12 This is a schematic diagram of a laser irradiation device with cracks. Figure 13 The diagram is based on Figure 12 A plan view of the substrate shown in a laser irradiation device when the tilt angle of the optical element does not change. Figure 14 The diagram is based on Figure 12 A plan view of the substrate shown in a laser irradiation device when the tilt angle of the optical element changes.

[0092] refer to Figures 12 to 14 When problems such as lens contamination or crack 135a occur in the laser irradiation device 100, abnormal parts 10b in the form of stripes may appear in the display device because the irradiation position of the laser beam is changed. Figure 12 The illustration shows a crack 135a appearing in the concave mirror 135, but the embodiments according to this disclosure are not limited thereto, and the crack may appear in the faceted mirror 131, the convex mirror 133, and / or the optical element 140.

[0093] If the tilt angle of the optical element 140 does not change and the optical element 140 remains horizontal, then as Figure 13 As shown, the anomalous crystallization portion 10b can appear in the form of stripes. The anomalous crystallization portion 10b can appear when the degree of crystallization differs from the surrounding environment. The anomalous crystallization portion 10b can be visually identified as stripes in the final manufactured device. To address or reduce this problem, some example embodiments include a method of dispersing the anomalous crystallization portion 10b by slightly altering the laser irradiation position via optical element 140.

[0094] In the laser irradiation apparatus 100 according to some example embodiments, the tilt angle of the optical element 140 can be changed after a laser beam scan and before the next scan is performed. When the tilt angle of the optical element 140 is changed between a laser beam scan and the next scan, such as Figure 14As shown, the abnormal crystallization portion 10b can be dispersed along the scan line SL. Therefore, since the visual recognition of the abnormal crystallization portion 10b in the form of stripes in the final manufactured device can be minimized or reduced, a display device with relatively uniform quality can be provided.

[0095] The scan lines SL on the substrate 10 can be dispersed along the first direction DR1, and the widths W1 and W2 of the crystalline region can be dispersed along the second direction DR2. Therefore, when the tilt angle of the optical element 140 is changed between the scanning of the laser beam and the next scan, even if there is lens contamination or cracks in the laser irradiation device 100, the abnormal portion 10b can be minimized or reduced, and a display device with relatively uniform quality can be provided.

[0096] Figure 15 This is a schematic diagram of a laser irradiation apparatus according to some example embodiments.

[0097] like Figure 15 As shown, the laser irradiation device 100_1 according to some example embodiments and according to the... Figure 1 The laser irradiation apparatus 100 described in the embodiments may differ in that it includes a plurality of first optical systems 130_1. The plurality of first optical systems 130_1 may be mounted or arranged adjacent to each other. For example, the first optical systems 130_1 may be alternately arranged with adjacent first optical systems 130_1 in the scanning direction of the laser beam, such that there is no unscanned region of the laser beam in the scanning direction of the laser beam. An optical element 140_1 may be mounted or arranged between the first optical system 130_1 and the substrate 10_1 on the substrate support 120_1, but the embodiments according to this disclosure are not limited thereto, and a plurality of optical elements 140_1 may be mounted between the first optical system 130_1 and the substrate 10_1. Different laser modules 150_1 may be connected to the first optical systems 130_1 respectively. Therefore, in the laser irradiation apparatus 100_1, since the first optical systems 130_1 and the laser modules 150_1 are arranged under different conditions, the amorphous silicon thin film can be crystallized under different conditions.

[0098] When problems such as lens contamination or cracks exist in the laser irradiation device 100_1, display abnormalities in the form of stripes can appear in the display device because the irradiation position of the laser beam can be changed. In the laser irradiation device 100_1 according to some example embodiments, the tilt angle of the optical element 140_1 can be changed during laser beam scanning. When the tilt angle of the optical element 140_1 is changed during laser beam scanning, the laser spot 20 on the substrate 10_1 can be rapidly dispersed along the first direction DR1, and the widths W1 and W2 of the crystalline region can be rapidly dispersed along the second direction DR2. Therefore, when the tilt angle of the optical element 140_1 is changed during laser beam scanning, even when lens contamination or cracks exist in the laser irradiation device 100_1, display abnormalities can be minimized or reduced, and a display device with relatively uniform quality can be provided.

[0099] Due to other content and references Figures 1 to 3 The content above is the same or similar, so some additional detailed descriptions can be omitted.

[0100] Those skilled in the art will understand that many variations and modifications can be made to the exemplary embodiments without substantially departing from the spirit and scope of the embodiments according to the present invention. Therefore, the exemplary embodiments of the present invention disclosed are used merely in a general and descriptive sense and not for limiting purposes. Rather, the embodiments according to this disclosure are defined by the appended claims and their equivalents.

Claims

1. A laser irradiation device, comprising: The laser module is configured to emit a laser beam; A first optical system is configured to scan the laser beam emitted from the laser module along a first direction; An optical element is configured to refract the laser beam emitted from the first optical system; A rotating rod is connected to the optical element and configured to rotate the optical element; as well as A substrate support is provided on which a base substrate is disposed. The laser beam refracted by the optical element reaches the base substrate to form multiple scanning lines. The first optical system includes a polygon mirror, a convex mirror, and a concave mirror, and When the optical element rotates, adjacent scan lines among the plurality of scan lines are offset relative to each other in the first direction.

2. The laser irradiation device according to claim 1, wherein, The first optical system includes a galvanometer and an f-theta lens.

3. The laser irradiation device according to claim 1, wherein, The optical element is configured such that the tilt angle of the optical element is changed by the rotation of the rotating rod.

4. The laser irradiation device according to claim 3, wherein, The tilt angle is configured to be changed after the laser beam is scanned on the substrate and before the next scan is performed.

5. The laser irradiation device according to claim 1, wherein, The laser module includes a fiber laser.

6. The laser irradiation device according to claim 1, wherein, The refractive index of the optical element is 1.3 to 2.

0.

7. The laser irradiation device according to claim 6, wherein, The optical element includes at least one of magnesium fluoride, calcium fluoride, yttrium aluminum garnet, quartz, and sapphire.

8. The laser irradiation device according to claim 1, wherein, The substrate support is configured to be movable in a direction perpendicular to the scanning direction of the laser beam.

9. The laser irradiation device according to claim 1, wherein: The first optical system has multiple components in the scanning direction of the laser beam; The first optical system and another first optical system adjacent to the first optical system are alternately arranged in the scanning direction of the laser beam, such that there is no region in the scanning direction of the laser beam that is not scanned.

Images