Laser irradiation method

Abstract

A laser irradiation method includes: a first scan in which a laser beam is scanned in a first region having a width in an X direction and a length in a Y direction by moving a laser irradiation region on a surface of a substrate in a Y direction using a spot laser beam; and a second scan in which a laser beam is scanned in a second region having a width in an X direction and a length in a Y direction by moving the laser irradiation region on the surface of the substrate in a Y direction using a spot laser beam. The center of the second region is spaced apart from the center of the first region in the X direction.

Description

Technical Field

[0001] The exemplary embodiments relate to a laser irradiation method and a laser irradiation apparatus used for the laser irradiation method. More particularly, the exemplary embodiments relate to a laser irradiation method for forming polycrystalline silicon and a laser irradiation apparatus used for the laser irradiation method. Background Art

[0002] Recently, display devices with light weight and small size have been manufactured. Cathode ray tube (CRT) display devices have been used due to performance and competitive price. However, CRT display devices have weaknesses in size or portability. Therefore, display devices such as plasma display devices, liquid crystal display devices, and organic light emitting display devices are highly valued due to their small size, light weight, and low power consumption.

[0003] The display device may include an active pattern of a thin film transistor, the active pattern including polysilicon. The polysilicon may be formed by crystallizing the amorphous silicon layer by irradiating an excimer laser to the amorphous silicon layer. Summary of the invention

[0004] The embodiment relates to a laser irradiation method for scanning on a surface of a substrate disposed in a plane formed by an X direction and a Y direction perpendicular to the X direction. The laser irradiation method includes: a first scan in which the laser beam is scanned in a first region having a width in the X direction and a length in the Y direction by moving the laser irradiation region on the surface of the substrate in the Y direction using a point laser beam; and a second scan in which the laser beam is scanned in a second region having a width in the X direction and a length in the Y direction by moving the laser irradiation region on the surface of the substrate in the Y direction using a point laser beam. The center of the second region is spaced apart from the center of the first region in the X direction.

[0005] The incident angle θ, divergence angle θy, and tilt angle φ of the laser beam relative to the substrate satisfy the following formulas.

[0006] <Formula>

[0007] θy[mrad]<9.33×θ[deg]

[0008] The incident angle θ may be greater than 0° (deg) and less than 7.5°.

[0009] The laser beam can be generated by a continuous oscillation laser oscillator or a pulsed oscillation laser oscillator having a repetition frequency of 30 MHz or higher.

[0010] The laser beam can be generated from YAG laser, YVO 4 Laser, YLF laser, YAlO 3 Laser, Y 2 O3 The solid-state laser is produced by selecting from among lasers, glass lasers, ruby ​​lasers, alexandrite lasers and titanium:sapphire lasers.

[0011] The convergence angle α of the laser beam may not exceed 30 mrad.

[0012] The laser beam may be irradiated onto the substrate through the laser light source, the first lens, and the scanner in sequence. The laser irradiation area may be moved by physical movement of the scanner.

[0013] The scanner is a rotatable galvanometric mirror.

[0014] The scanner is a rotatable polygonal mirror.

[0015] The diameter of the laser beam at the laser light source generating the laser beam may be less than or equal to 10 mm. The diameter of the laser beam on the substrate may be less than or equal to 100 μm. The optical path from the laser light source to the substrate may be greater than 1 meter.

[0016] The laser irradiation method may include forming an amorphous silicon layer on a substrate, and irradiating a laser beam onto the amorphous silicon layer to crystallize the amorphous silicon layer.

[0017] The first region and the second region may partially overlap each other.

[0018] The embodiment also relates to a laser irradiation device for irradiating a laser beam onto a substrate, the laser irradiation device comprising a laser light source for generating a laser beam, a first lens through which the laser beam generated from the laser light source passes, and a scanner for reflecting the laser beam having passed through the first lens, and the scanner changes the direction of the reflected laser beam. An incident angle θ, a divergence angle θy, and an inclination angle φ of the laser beam relative to the substrate satisfy the following formula.

[0019] <Formula>

[0020] θy[mrad]<9.33×θ[deg]

[0021] The incident angle θ may be greater than 0° (deg) and less than 7.5°.

[0022] The laser beam may be generated by a continuous oscillation type laser oscillator or a pulse oscillation type laser oscillator having a repetition frequency of 30 MHz or higher.

[0023] The laser oscillator can be from YAG laser, YVO 4 Laser, YLF laser, YAlO 3 Laser, Y 2 O 3 Solid-state lasers selected from among lasers, glass lasers, ruby ​​lasers, alexandrite lasers and titanium:sapphire lasers.

[0024] The convergence angle α of the laser beam may not exceed 30 mrad.

[0025] The scanner may be a rotatable polygonal mirror.

[0026] The scanner may be a rotatable galvanometric mirror.

[0027] The diameter of the laser beam at the laser light source generating the laser beam may be less than or equal to 10 mm, the diameter of the laser beam on the substrate may be less than or equal to 100 μm, and the optical path from the laser light source to the substrate may be greater than 1 m. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Various features will become apparent to those skilled in the art by describing in detail exemplary embodiments with reference to the accompanying drawings, in which:

[0029] Figure 1 illustrates a plan view of a substrate 10 on which a laser irradiation method according to an exemplary embodiment is performed;

[0030] Figure 2 Picture shows Figure 1 A side view of a substrate 10;

[0031] Figure 3 It is shown in Figure 1 A diagram of the incident angle θ, divergence angle θy and tilt angle φ components of the laser beam in the laser irradiation method;

[0032] Figure 4 The diagram shows Figure 1 Schematic diagram of crystal changes of polycrystalline silicon according to changes in the incident angle θ and the divergence angle θy of the laser beam in the laser irradiation method;

[0033] Figure 5A and Figure 5B The diagram shows Figure 4 Images of polysilicon crystals of sample 1 and sample 2;

[0034] Figure 6 A diagram showing an angular distribution AD of a laser beam of a conventional laser irradiation device 50 is illustrated;

[0035] Figure 7 The diagram shows Figure 1 A diagram of a convergence angle α of a laser beam in a laser irradiation method;

[0036] Fig. 8A and Figure 8B A diagram illustrating a laser irradiation apparatus 100 according to an exemplary embodiment; and

[0037] Fig.9A and Fig. 9BA diagram of a laser irradiation apparatus 200 according to an exemplary embodiment is illustrated. DETAILED DESCRIPTION

[0038] Exemplary embodiments will now be described more fully below with reference to the accompanying drawings, however, these embodiments may be embodied in different forms and should not be construed as being limited to the embodiments presented herein. On the contrary, these embodiments are provided to make this disclosure comprehensive and complete and to fully convey exemplary implementations to those skilled in the art.

[0039] In the accompanying drawings, the sizes of layers and regions may be exaggerated for clarity of illustration. It will also be understood that when a layer or element is referred to as being "on" another layer or substrate, it may be directly on the other layer or substrate, or there may be an intermediate layer. In addition, it will be understood that when a layer is referred to as being "below" another layer, it may be directly below, or there may be one or more intermediate layers. In addition, it will be understood that when a layer is referred to as being "between" two layers, it may be the only layer between the two layers, or there may be one or more intermediate layers. Throughout the text, the same reference numerals refer to the same elements.

[0040] Figure 1 A plan view of a substrate 10 on which a laser irradiation method according to an exemplary embodiment is performed is illustrated. Figure 2 Picture shows Figure 1 10 is a side view of the substrate 10.

[0041] refer to Figure 1 and Figure 2 According to the laser irradiation method, a point laser beam may be scanned multiple times on the substrate 10 in the Y direction y perpendicular to the X direction x to irradiate the entire substrate 10. In this way, the entirety of the substrate 10 may be subjected to laser processing. Hereinafter, the details of the laser irradiation method will be described.

[0042] According to the laser irradiation method, a laser beam is irradiated onto the surface of the substrate 10 using a point laser beam. The laser beam may be irradiated onto the surface of the substrate 10. The laser irradiation area irradiated using the laser beam may be moved along the Y direction y. Therefore, the laser beam may be irradiated onto a line area using a point laser beam. Therefore, the laser beam may be scanned in a first area having a width in the X direction x and a length in the Y direction y (first scanning step, see Figure 1 The arrow corresponding to ① in the figure).

[0043] The irradiation point of the spot laser beam may be moved by a predetermined distance in the X direction x, and then the laser beam may be irradiated onto the surface of the substrate 10 so that the laser irradiation area irradiated with the laser beam may be moved in the Y direction y. Thus, the laser beam may be scanned in a second area having a width in the X direction x and a length in the Y direction y (second scanning step, see Figure 1 The arrow corresponding to ② in the figure).

[0044] Thereafter, the irradiation point of the spot laser beam may be moved by a predetermined distance in the X direction x, and then the laser beam may be irradiated onto the surface of the substrate 10 so that the laser irradiation area irradiated with the laser beam may be moved in the Y direction y. Thus, the laser beam may be scanned in a third area having a width in the X direction x and a length in the Y direction y (third scanning step, see Figure 1 The arrow corresponding to ③ in the figure).

[0045] The above steps may be repeated to irradiate the entire substrate 10 with the laser beam.

[0046] Centers of the first to third regions may be spaced apart by a certain distance in the X-direction x, and the first to third regions may partially overlap with each other.

[0047] The laser beam can be scanned at a speed of about 30 m / s, and the moving pitch along the X direction x can be about 2 mm. The incident angle θ of the laser beam (see Figure 3 ) can be about 7° (degrees), and the divergence angle θy (see Figure 3 ) can be approximately 0±15 mrad (milliradians).

[0048] An amorphous silicon layer may be formed on the substrate 10. The amorphous silicon layer may be crystallized by laser irradiation to form polycrystalline silicon. For example, crystallization due to almost complete melting of amorphous silicon may be caused by the irradiated laser beam.

[0049] Typically, when the laser beam has an energy per light source pulse of 1 J or greater and the energy density on the substrate 10 is about 470 mJ / cm^2, polycrystalline silicon crystals in a square form with a crystal size of about 300 nm (nanometers) with relatively high uniformity can be obtained.

[0050] Figure 3 It is shown in Figure 1 Graph of the incident angle θ, divergence angle θy and tilt angle φ components of the laser beam in the laser irradiation method.

[0051] refer to Figure 3 , showing the incident angle θ, divergence angle θy and tilt angle φ of the laser beam generated by the laser light source LS relative to the substrate 10. Here, the incident angle θ, divergence angle θy and tilt angle φ components have the following relationship: When line (OA) = 1,

[0052] Line (OB) = tan (φ)

[0053] Line (O-LS) = 1 / sin(θ)

[0054] (OB / O-LS) = tan(θy)

[0055] To summarize, when θy = arctan(tanφ×sinθ), the above relationship can be obtained.

[0056] When the tilt angle φ increases, the protrusion angle of the polysilicon layer on the substrate 10 changes, and the orientation deteriorates. When the laser beam does not have a tilt angle φ component, the grains of polysilicon form quadrilateral crystals. When the tilt angle φ component increases, the grains become polygonal. When the tilt angle φ is 30°, hexagonal stable crystals (grains) are formed. Thereafter, when the tilt angle φ is greater than 30°, the crystals become irregular squares, and the orientation is reduced.

[0057] Figure 4 It is shown in Figure 1 Schematic diagram of crystal properties of polycrystalline silicon according to changes in the incident angle θ and the divergence angle θy of the laser beam in the laser irradiation method. Figure 5A and Figure 5B Picture shows Figure 4 Images of polysilicon crystals of Sample 1 and Sample 2.

[0058] refer to Figure 3 and Figure 4 Based on the above description, assuming that orientation occurs when the tilt angle φ is 30 degrees or less, by calculating this, it can be obtained that Figure 4 For example, the schematic diagram shows the range of divergence angle θy of the oriented crystal that can be obtained according to the incident angle θ. For example, it can be understood that when the incident angle θ and the divergence angle θy are located in the shaded area of ​​the schematic diagram, a crystal with excellent orientation can be obtained.

[0059] When the shaded area of ​​the schematic diagram is expressed as a formula, the following formula is obtained.

[0060] <Formula>

[0061] θy[mrad]<9.33×θ[deg]

[0062] refer to Figure 5A and Figure 5B , when a laser beam corresponding to the incident angle shown for Sample 1 (SAMPLE1) and Sample 2 (SAMPLE2) is irradiated, square grains (crystals) with high orientation can be obtained under the conditions corresponding to Sample 2 (SAMPLE2).

[0063] Figure 6 A graph showing the angle distribution AD of a laser beam of a conventional laser irradiation device 50 is illustrated.

[0064] refer to Figure 6, the conventional laser irradiation device 50 may include a first lens LN1, a second lens LN2, a beam homogenizer HZ, and a third lens LN3. The laser beam generated from the laser light source of the laser irradiation device 50 passes through the first lens LN1, the second lens LN2, the beam homogenizer HZ, and the third lens LN3 in sequence. The laser beam may be irradiated onto the substrate 10 in the form of a line beam.

[0065] here, Figure 6 The vertical direction in is the long side direction of the line beam, and the illustrated laser path shows the optical system of the laser irradiation device 50 in the long side direction of the line beam.

[0066] The beam homogenizer HZ may receive a laser beam having energy density of Gaussian distribution, and may convert the laser beam into a laser beam having uniform energy density in one direction.

[0067] The angle distribution AD due to the path difference of the laser beam is shown in this figure. It is confirmed by experiment that when the angle distribution AD is too large, the orientation of the grains of polycrystalline silicon on the substrate 10 is poor. When the angle distribution AD is 40 mrad (milliradians), the orientation is shown to be excellent, but when the angle distribution AD is 62 mrad, the orientation is shown to be poor.

[0068] That is, the orientation of the crystal of polycrystalline silicon is related to the angle distribution AD of the laser beam. When the angle distribution AD does not exceed a certain degree, good orientation can be obtained.

[0069] Figure 7 The diagram shows Figure 1 FIG. 1 is a diagram of a convergence angle α of a laser beam in a laser irradiation method.

[0070] refer to Figure 7 The laser irradiation method according to the embodiment irradiates a point laser beam in a scanning manner different from that of the conventional laser irradiation device 50 , so that the influence of the angle distribution may be different from that in the conventional laser irradiation device 50 .

[0071] As shown in the figure, the distance from the laser light source LS to the substrate 10 is referred to as an optical path L, the diameter of the laser beam in the laser light source LS is referred to as D1, and the diameter of the laser beam on the substrate 10 is referred to as D2. The convergence angle α indicating the convergence degree of the laser beam can be expressed by α=arctan((D1-D2) / 2L).

[0072] The angle distribution AD of the spot laser beam of the scanning method as in the present embodiment may be as follows.

[0073] (AD) = 2*(convergence angle α)

[0074] based on Figure 6As described in, the angular distribution AD can have a value not exceeding 60 mrad to obtain good orientation. The desired range of the convergence angle α can be as follows.

[0075] (Convergence angle α) < 30 mrad

[0076] Generally, when D1 is much larger than D2, the convergence angle α can satisfy the following formula.

[0077] <Formula>

[0078] Convergence angle α < arctan((D1 / 2) / L) = 5 mrad (milliradians)

[0079] In one example, when the diameter D1 of the laser beam at the laser light source LS is about 10 mm and the diameter D2 of the laser beam on the substrate 10 is about 100 μm (micrometers), and the optical path L is 1 m (1 meter), since D1 is much larger than D2, the convergence angle α can be calculated as 5 mrad (milliradians) by the above formula. Therefore, when the convergence angle α is less than 30 mrad, it can be expected that excellent orientation of polycrystalline silicon crystals can be obtained.

[0080] As described above, in order to satisfy (convergence angle α) << 30 mrad, D1, D2, and L of the laser irradiation device can be designed.

[0081] Fig. 8A And Figure 8B is a diagram showing a laser irradiation device 100 according to an exemplary embodiment.

[0082] Reference Fig. 8A And Figure 8B , the laser irradiation device 100 can include a laser light source LS, a first lens LN1, a first mirror MR1, a second mirror MR2, and a third mirror MR3. The laser irradiation device 100 can irradiate a spot laser beam onto the surface of the substrate 10 in a scanning manner. Fig. 8A The dashed line in shows one scan for one scanning area (refer to the first scanning step in the description of Figure 1 And Figure 2 ).

[0083] The laser light source LS can be a laser oscillator. The laser beam is generated by a continuous oscillation type laser oscillator or a pulse oscillation type laser oscillator having a repetition frequency of 30 MHz or higher. For example, the laser oscillator can emit a laser beam having a wavelength of 532 nm at a repetition frequency of 30 MHz, or emit a laser beam having a wavelength of 355 nm. For example, when the laser oscillator uses a Nd:YAG laser (1064 nm) solid-state laser, the second harmonic can have a wavelength of 532 nm, and the third harmonic can have a wavelength of 355 nm.

[0084] The laser oscillator can use an appropriate continuous oscillation solid-state laser. Examples of solid-state lasers include YAG lasers, YVO lasers, 4 Laser, YLF laser, YAlO 3 Laser, Y 2 O 3 Lasers, glass lasers, ruby ​​lasers, alexandrite lasers, titanium:sapphire lasers, etc.

[0085] The laser beam emitted from the laser light source LS may enter the first lens LN1. The first lens LN1 may be a light converging optical system. For example, the first lens LN1 may be a spherical lens or a Fresnel lens. After passing through the first lens LN1, the laser beam may be reflected by the first mirror MR1.

[0086] The first mirror MR1 may be a galvanometer mirror. The first mirror MR1 may be rotated to change the angle at which the laser beam is reflected. For example, the first mirror MR1 may be used as a scanner for changing the direction of the reflected laser beam.

[0087] The laser beam reflected from the first mirror MR1 may be sequentially reflected by the second mirror MR2 and the third mirror MR3. The second mirror MR2 may be a convex mirror, and the third mirror MR3 may be a concave mirror.

[0088] The laser beam reflected from the third mirror MR3 may be irradiated onto the substrate 10 .

[0089] The point laser beam generated by the laser light source LS can pass through the first lens LN1 and be reflected by the first mirror MR1,

[0090] The second mirror MR2 and the third mirror MR3 reflect to position Thereafter, the first mirror MR1 may be rotated to move the laser irradiation area irradiated with the laser beam in the Y direction y (refer to to Therefore, a point laser beam can be used to irradiate the laser beam to the line area as one scan.

[0091] The irradiation position of the spot laser beam may be moved by a predetermined distance in the X direction x, and the laser beam may be irradiated to the entire substrate 10 by repeating laser scanning.

[0092] For example, a laser beam having a wavelength of 532 nm, a frequency of 30 MHz, a FWHM of 15 μm, an energy density of 250 mJ / cm^2, a laser scanning speed of 30 m / s, a moving pitch of 2 mm in the X direction x, an incident angle θ of 7°, and a divergence angle θy of 0±15 mrad may be irradiated onto the substrate 10. The first lens LN1, the first mirror MR1, the second mirror MR2, and the third mirror MR3 of the laser irradiation device 100 may be configured to satisfy the conditions of the laser beam.

[0093] For example, the incident angle θ may be greater than 0° (deg) and less than 7.5°. If the incident angle θ is greater than 0 degrees, the reflected light and the refracted light may interfere with each other at the protrusions on the silicon surface to generate surface waves. The intensity period of the surface waves may cause grain growth.

[0094] The convergence angle α of the laser beam may be 30 mrad or less. The incident angle θ, the divergence angle θy, and the tilt angle φ of the laser beam relative to the substrate 10 may satisfy the following formula.

[0095] <Formula>

[0096] θy[mrad]<9.33×θ[deg]

[0097] Furthermore, as described above, the convergence angle α of the laser beam may be 30 mrad or less.

[0098] The laser scanning speed can be adjusted according to the rotation speed of the first mirror MR1.

[0099] An amorphous silicon layer may be formed on the substrate 10 , and the amorphous silicon layer may be crystallized by laser irradiation to form polycrystalline silicon.

[0100] According to the present embodiment, when using the laser irradiation device 100, crystallization can be performed by scanning a spot laser beam at high speed. At this time, when using a high-frequency solid-state laser light source, the process cost can be reduced compared to excimer laser annealing using a conventional gas laser device.

[0101] Furthermore, when the laser beam is irradiated while maintaining the incident angle θ, the divergence angle θy, and the convergence angle α under certain conditions, a polygonal crystal having a good orientation can be formed.

[0102] The plurality of lenses and mirrors of the laser irradiation device 100 may be designed so that characteristics of the laser light, such as the divergence angle θy, may be kept constant during the laser scanning process.

[0103] In the example, when the wavelength is 532nm, the frequency is 30MHz, the beam size (FWHM) is 15mm, the energy density is 250mJ / cm^2, the beam scanning speed is 30m / s, the moving spacing along the X direction x is 2mm, θ is 7°, and θy is 0±15mrad, AFM analysis of the polysilicon crystal layer irradiated by the laser beam shows a protrusion orientation with a period of approximately 550nm and no multiple interference in the FFT (Fast Fourier Transform) graph.

[0104] On the other hand, when the divergence angle θy is 70 mrad or more during laser scanning, it is found that the orientation of the crystal disappears. Therefore, the appropriate divergence angle θy may preferably be 70 mrad or less. Therefore, it can be seen that, using the above formula, the desired range of the incident angle is less than 7.5° (degrees).

[0105] Fig.9A and Fig. 9B is a diagram illustrating a laser irradiation device 200 according to the embodiment.

[0106] refer to Fig.9A and Fig. 9B , the laser irradiation device 200 can be used with Fig. 8A and Figure 8B The laser irradiation device 100 is substantially the same except for the optical system arranged in the path of the laser beam. Therefore, the repeated description will be briefly described.

[0107] The laser irradiation device 200 may include a laser light source LS, a first lens LN1, a first mirror MR1, and a second lens LN2. The laser irradiation device 200 may irradiate a point laser beam onto the surface of the substrate 10 in a scanning manner. Figure 1 and Figure 2 Similar to the first scanning step in the description of Fig.9A The dotted line in shows one scan for one scan area.

[0108] The laser light source LS may be a laser oscillator. The laser beam may be generated by a continuous oscillation type laser oscillator or a pulse oscillation type laser oscillator having a repetition frequency of 30 MHz or higher.

[0109] As the laser oscillator, an appropriate continuous oscillation solid-state laser can be used.

[0110] The laser beam emitted from the laser light source LS may enter the first lens LN1. The first lens LN1 may be a light converging optical system. The first lens LN1 may be, for example, a spherical lens or a Fresnel lens. The laser beam having passed through the first lens LN1 may be reflected by the first mirror MR1.

[0111] The first mirror MR1 may be a polygonal mirror. The first mirror MR1 may rotate to change the angle at which the laser beam is reflected. For example, the first mirror MR1 may be used as a scanner for changing the direction of the reflected laser beam.

[0112] The laser beam deflected by the first mirror MR1 may pass through the second lens LN2. The second lens LN2 may be an f-θ lens. The f-θ lens may collect the laser beam so as to always focus on the substrate 10 to be irradiated.

[0113] The laser beam having passed through the second lens LN2 may be irradiated onto the substrate 10 .

[0114] The point laser beam generated by the laser light source LS can pass through the first mirror MR1 and the second lens LN2 to be at position Thereafter, the first mirror MR1 can be rotated to move the laser irradiation area irradiated with the laser beam in the Y direction y (refer to arrive Therefore, a point laser beam can be used to irradiate the laser beam onto a line area in one scan.

[0115] The irradiation position of the spot laser beam may be moved by a predetermined distance in the X direction x, and the laser beam may be irradiated to the entire substrate 10 by repeating laser scanning.

[0116] The ranges of the incident angle θ, the divergence angle θy, the tilt angle φ, and the convergence angle α of the laser beam may be as described above.

[0117] The laser beam scanning speed can be adjusted according to the rotation speed of the first mirror MR1 which is a polygon mirror.

[0118] According to the laser irradiation method, a laser beam may be irradiated onto a surface of a substrate disposed in a plane formed by an X direction and a Y direction perpendicular to the X direction. The laser irradiation method includes: a first scanning step in which the laser beam is scanned in a first region having a width in the X direction and a length in the Y direction by moving the laser irradiation region on the surface of the substrate in the Y direction using a point laser beam; and a second scanning step in which the laser beam is scanned in a second region having a width in the X direction and a length in the Y direction by moving the laser irradiation region on the surface of the substrate in the Y direction using a point laser beam. The center of the second region may be spaced apart from the center of the first region in the X direction.

[0119] The laser irradiation device for performing the laser irradiation method can irradiate the laser beam onto the substrate by a scanning method using a point laser beam. At this time, the incident angle θ, the divergence angle θy and the inclination angle φ of the laser beam can satisfy θy [mrad] <9.33 × θ [deg], and the convergence angle α can be 30 mrad or less. Thus, a laser irradiation method and a laser irradiation device for producing excellent quality polycrystalline silicon can be provided while reducing costs.

[0120] The embodiments can be applied to the manufacture of organic light emitting displays and various electronic devices including the organic light emitting displays. For example, the embodiments can be applied to the manufacture of mobile phones, smart phones, video phones, smart tablets, smart watches, tablet computers, car navigation systems, televisions, computer monitors, notebooks, etc.

[0121] By summarizing and reviewing, a laser beam in the form of a line beam can be scanned at a constant pitch on an amorphous silicon layer on a substrate to perform a crystallization process. Generally, a gas laser is used to form a line beam through a gas tube. Therefore, there are great problems in the manufacturing cost and maintenance cost of the laser irradiation device.

[0122] In addition, the size and shape of crystals may vary depending on the laser irradiation method, and various attempts have been made to obtain uniformly arranged polygonal crystals in polysilicon of thin film transistors.

[0123] The embodiment provides a laser irradiation method capable of forming high-quality polycrystalline silicon while reducing costs.

[0124] The embodiment also provides a laser irradiation device for use in the laser irradiation method.

[0125] Exemplary embodiments have been disclosed herein, and although specific terms are used, they are used and interpreted in a general and descriptive sense only and not for purposes of limitation. In some cases, as will be apparent to one of ordinary skill in the art at the time of filing this application, features, characteristics, and / or elements described in conjunction with a particular embodiment may be used alone or in combination with features, characteristics, and / or elements described in conjunction with other embodiments, unless expressly stated otherwise. Therefore, it should be understood by those skilled in the art that various changes in form and detail may be made without departing from the spirit and scope of the present disclosure as set forth in the appended claims.

Claims

1. A laser irradiation method for scanning on a surface of a substrate arranged in a plane formed by an X direction and a Y direction perpendicular to the X direction, the laser irradiation method comprising: a first scan in which a laser beam is scanned in a first area having a width in the X direction and a length in the Y direction by moving a laser irradiation area on the surface of the substrate in the Y direction using a spot laser beam; as well as a second scan in which the laser beam is scanned in a second area having a width in the X direction and a length in the Y direction by moving the laser irradiation area on the surface of the substrate in the Y direction using the spot laser beam, and wherein the center of the second region is spaced apart from the center of the first region in the X direction, wherein the convergence angle α of the laser beam in the X direction does not exceed 30 mrad, and The incident angle θ of the laser beam and the divergence angle θy of the laser beam in the Y direction satisfy the following formula: <Formula> θy[mrad]<9.33×θ[deg].

2. The laser irradiation method according to claim 1, wherein: The incident angle θ is greater than 0° and less than 7.5°.

3. The laser irradiation method according to claim 1, wherein: The laser beam is generated by a continuous oscillation laser oscillator or a pulsed oscillation laser oscillator having a repetition frequency of 30 MHz or higher.

4. The laser irradiation method according to claim 1, wherein: The laser beam is generated by a solid laser selected from a YAG laser, a YVO4 laser, a YLF laser, a YAlO3 laser, a Y2O3 laser, a glass laser, a ruby ​​laser, an alexandrite laser and a titanium:sapphire laser.

5. The laser irradiation method according to claim 1, wherein: The laser beam is irradiated onto the substrate through a laser light source, a first lens, and a scanner in sequence, and the laser irradiation area is moved by physical movement of the scanner.

6. The laser irradiation method according to claim 5, wherein: The scanner is a rotatable galvanometric mirror.

7. The laser irradiation method according to claim 5, wherein: The scanner is a rotatable polygonal mirror.

8. The laser irradiation method according to claim 1, wherein: The diameter of the laser beam at the laser light source generating the laser beam is less than or equal to 10 mm, the diameter of the laser beam on the substrate is less than or equal to 100 μm, and the length of the optical path from the laser light source to the substrate is greater than 1 meter.

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