Laser annealing equipment

Abstract

The present invention relates to a laser annealing device and a laser annealing method. The laser annealing device comprises: a light source that emits continuously oscillating laser light; and an optical head that processes individual laser beams emitted from the light source into convergent laser beams. The laser beams are projected onto a target region for modification located above a gate line. The optical head relatively scans the laser beam within the target region for modification along the direction in which the gate line extends, with the most convergent point of the laser beam located within the amorphous silicon film in the target region for modification.

Description

Technical Field

[0001] The invention relates to a laser annealing device and a laser annealing method. Background Art

[0002] In thin-film displays (FPDs) such as liquid crystal displays (LCDs) and organic electroluminescence displays (OLEDs), the size and definition of these displays are increasing.

[0003] An FPD includes a TFT substrate on which thin-film transistors (TFTs) are formed. A TFT substrate has microscopic TFTs for active driving formed on each pixel arranged in a matrix. For example, a display with full HD resolution (1920×1080 resolution) and 120Hz operation may contain over 10 million pixels.

[0004] Materials used to form the semiconductor layers of TFTs include amorphous silicon (a-Si) and polycrystalline silicon (p-Si). Amorphous silicon has low mobility, an indicator of electron mobility, and cannot fully meet the high mobility required by high-density and high-definition FPDs. Therefore, for TFTs in FPDs, it is preferable to use semiconductor layers made of polycrystalline silicon, which has higher mobility than amorphous silicon.

[0005] In recent years, as a method for forming polycrystalline silicon or quasi-single-crystal silicon by lateral crystal growth, there has been a method of scanning a linear beam of a green continuous wave (CW) laser light with a wavelength of approximately 532 nm across multiple rows of amorphous silicon films processed into strips or islands (see, for example, Patent Document 1). In this method, the area where the amorphous silicon film is formed is limited to the TFT formation area, thereby reducing the area of the amorphous silicon film heated by laser annealing. This is done in an attempt to prevent the temperature of the glass substrate from rising due to heat from the amorphous silicon film, which could cause cracks, and to prevent impurities from diffusing into the material film.

[0006]

Prior technical literature

[0007] [Patent Literature]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-86505 Summary of the Invention

[0009] [Summary of the Invention]

[0010] [Problems to be solved by the invention]

[0011] The conventional laser annealing method using a CW laser, as described above, presents the following issues. Even if the amorphous silicon film is minimized in this laser annealing method, metal wiring patterns such as gate lines and the glass substrate exist below (in the lower layer) the amorphous silicon film that constitutes the TFT. Furthermore, because the laser beam oscillates continuously, heat accumulates and stagnates on the glass substrate, causing overheating and damage to the metal wiring patterns such as gate lines and the glass substrate. Furthermore, when using a blue or green laser with a wavelength of approximately 400 to 550 nm, the beam reaches the metal wiring patterns such as gate lines and the glass substrate below the amorphous silicon film. This, combined with the effect of the stagnant heat, can cause overheating and damage to the metal wiring patterns such as gate lines and the glass substrate. In particular, the laser annealing method using a CW laser is difficult to use with flexible substrates, such as those made of resins such as polyimide. Furthermore, in the laser annealing method using CW laser, since a linear laser beam is used, areas other than the active semiconductor layer of the TFT (areas from which the amorphous silicon film is removed) are also annealed, resulting in poor energy utilization efficiency.

[0012] The present invention has been made in view of the above-mentioned problems, and its object is to provide a laser annealing device and a laser annealing method that effectively crystallize the amorphous silicon film only in the area where TFTs are formed without causing thermal damage to the substrate and wiring layers arranged below the amorphous silicon film.

[0013]

Solutions to Solve the Problem

[0014] In order to solve the above-mentioned problems and achieve the purpose, a laser annealing device is provided, wherein a gate line is formed on a substrate, and an amorphous silicon film is formed on the upper layer of the gate line in a manner covering the entire gate line. The laser annealing device irradiates the amorphous silicon film with a continuous oscillation laser to modify the intended modification area of the amorphous silicon film into a crystallized film. The device is characterized in that the laser annealing device comprises: a light source that emits a continuously oscillating laser; an optical head that processes the laser emitted from the light source into a convergent laser beam, the laser beam can be correspondingly projected into the intended modification area located above the gate line, and the optical head relatively scans the laser beam in the intended modification area in a state where the most convergent point of the laser beam is located inside the amorphous silicon film in the intended modification area.

[0015] Another embodiment of the present invention relates to a laser annealing device, in which a gate line is formed on a substrate, and an amorphous silicon film is formed on the upper layer of the gate line in a manner covering the entire substrate. The laser annealing device irradiates the amorphous silicon film with a continuous oscillation laser to modify the intended modification area of the amorphous silicon film into a crystallized film. The device is characterized in that the laser annealing device comprises: a light source that emits a continuously oscillating laser; an optical head that processes the laser emitted from the light source into a convergent laser beam, the laser beam being capable of being projected correspondingly onto the intended modification area located above the gate line, and the optical head relatively scans the laser beam over a specified area including the intended modification area in a state where the most convergent point of the laser beam is located inside the amorphous silicon film in the intended modification area.

[0016] Another embodiment of the present invention relates to a laser annealing device, in which a gate line is formed on a substrate, and an amorphous silicon film is formed on the upper layer of the gate line in a manner that covers the entire gate line. The laser annealing device irradiates the amorphous silicon film with a continuous oscillation laser to modify the intended modification area of the amorphous silicon film into a crystallized film. The device is characterized in that the laser annealing device comprises: a light source that emits continuously oscillating laser light; an optical head that processes the laser emitted from the light source into a convergent laser beam, and the laser beam can be projected correspondingly into the intended modification area located above the gate line. The optical head relatively scans the laser beam in the intended modification area in a state in which an area including the focus of the laser beam and the vicinity of the focus and the beam profile maintaining a top hat shape overlaps with an area inside the amorphous silicon film in the intended modification area.

[0017] Another form of the present invention relates to a laser annealing device, in which a gate line is formed on a substrate, and an amorphous silicon film is formed on the upper layer of the gate line in a manner covering the entire substrate. The laser annealing device irradiates the amorphous silicon film with a continuous oscillation laser to modify the intended modification area of the amorphous silicon film into a crystallized film. The device is characterized in that the laser annealing device comprises: a light source that emits continuously oscillating laser light; an optical head that processes the laser emitted from the light source into a convergent laser beam, and the laser beam can be projected correspondingly into the intended modification area located above the gate line. The optical head relatively scans the laser beam in a specified area including the intended modification area, in a state in which an area including the focus of the laser beam and the vicinity of the focus and the beam profile maintaining a top hat shape overlaps with an area inside the amorphous silicon film of the intended modification area.

[0018] As the above aspect, it is preferable that the laser light emitted from the light source is guided to an optical fiber provided in the optical head.

[0019] In the above aspect, it is preferable that the cross-sectional shape of the optical fiber perpendicular to the optical axis direction is square, rectangular, or hexagonal.

[0020] Another form of the present invention relates to a laser annealing device, in which a plurality of gate lines parallel to each other are formed on a substrate, an amorphous silicon film is formed on the upper layer of the plurality of gate lines in a manner covering the entirety of the plurality of gate lines, the laser annealing device irradiates the amorphous silicon film with a continuous oscillation laser to modify the intended modification area of the amorphous silicon film into a crystallized film, and is characterized in that the laser annealing device comprises: a plurality of light sources, which respectively emit continuously oscillating lasers; an optical head, which processes each of the lasers emitted from the plurality of light sources into a convergent laser beam, each of the laser beams being projected sequentially and correspondingly into the intended modification area located above the gate lines, and the optical head relatively scans the laser beam within the intended modification area in a state in which the most convergent point of each laser beam is located inside the amorphous silicon film in the intended modification area.

[0021] Another form of the present invention relates to a laser annealing device, in which a plurality of gate lines parallel to each other are formed on a substrate, an amorphous silicon film is formed on the upper layer of the plurality of gate lines in a manner covering the entire substrate, the laser annealing device irradiates the amorphous silicon film with a continuous oscillation laser to modify the intended modification area of the amorphous silicon film into a crystallized film, and is characterized in that the laser annealing device comprises: a plurality of light sources, which respectively emit continuously oscillating lasers; an optical head, which processes each of the lasers emitted from the plurality of light sources into a convergent laser beam, each of the laser beams being able to be projected sequentially and correspondingly onto the intended modification area located above the gate lines, and the optical head relatively scans the laser beam in a specified area including the intended modification area in a state in which the most convergent point of each laser beam is located inside the amorphous silicon film in the intended modification area.

[0022] Another form of the present invention relates to a laser annealing device, in which a plurality of gate lines parallel to each other are formed on a substrate, an amorphous silicon film is formed on the upper layer of the plurality of gate lines in a manner covering the entirety of the plurality of gate lines, the laser annealing device irradiates the amorphous silicon film with a continuous oscillation laser to modify the intended modification area of the amorphous silicon film into a crystallized film, and is characterized in that the laser annealing device comprises: a plurality of light sources, each of which emits a continuously oscillating laser; an optical head, which processes each of the lasers emitted from the plurality of light sources into a convergent laser beam, each of the laser beams being projected sequentially and correspondingly onto the intended modification area located above the gate lines, the optical head relatively scans the laser beam within the intended modification area in a state where an area including the focus and the vicinity of the focus of each laser beam and where the beam profile maintains a top hat shape overlaps with an area inside the amorphous silicon film of the intended modification area.

[0023] Another form of the present invention relates to a laser annealing device, in which a plurality of gate lines parallel to each other are formed on a substrate, an amorphous silicon film is formed on the upper layer of the plurality of gate lines in a manner covering the entire substrate, the laser annealing device irradiates the amorphous silicon film with a continuous oscillation laser to modify the intended modification area of the amorphous silicon film into a crystallized film, and is characterized in that the laser annealing device comprises: a plurality of light sources, each of which emits a continuously oscillating laser; an optical head, which processes each of the lasers emitted from the plurality of light sources into a convergent laser beam, each of the laser beams being projected sequentially and correspondingly onto the intended modification area located above the gate lines, the optical head relatively scans the laser beam over a specified area including the intended modification area in a state where an area including a focus and the vicinity of the focus in each laser beam and a beam profile maintaining a top hat shape overlaps with an area inside the amorphous silicon film of the intended modification area.

[0024] In the above aspect, preferably, the region to be reformed is a channel semiconductor layer of a thin film transistor.

[0025] As the above aspect, it is preferable that the laser beam emitted from the optical head is projected onto the surface of the amorphous silicon film in a manner arranged at a constant pitch along a predetermined straight line.

[0026] As the above aspect, it is preferable that the optical head is rotatably movable so that a pitch between the plurality of laser beams is equal to a pitch between gate lines.

[0027] As the above aspect, the laser annealing apparatus preferably includes a light quantity sensor that detects the light quantity of each of the plurality of laser beams, and can adjust the output of the light source emitting the laser beam based on the light quantity of the laser beam detected by the light quantity sensor.

[0028] As the above aspect, it is preferable that the light amount sensor is arranged behind the optical head.

[0029] As the above aspect, it is preferable that the optical head includes a beam splitter that reflects the laser beam laterally, and the light amount sensor is arranged on the side of the optical head.

[0030] As the above aspect, it is preferable that the optical head includes a scanning mirror configured to reflect the laser beam laterally, and the light amount sensor is arranged laterally of the optical head.

[0031] As the above aspect, it is preferable that the laser beams emitted from the plurality of light sources are guided to optical fibers of an optical fiber array provided in the optical head.

[0032] As the above aspect, it is preferable that the optical head includes the optical fiber array and an imaging optical system, the optical fiber array is movable in the optical axis direction by an actuator, and the imaging optical system is composed of a telecentric optical system.

[0033] In the above aspect, it is preferable that the cross-sectional shape of the optical fiber perpendicular to the optical axis direction is square, rectangular, or hexagonal.

[0034] Another form of the present invention relates to a laser annealing method, wherein a gate line is formed on a substrate, and an amorphous silicon film is formed on the upper layer of the gate line in a manner that covers the entire gate line. In the laser annealing method, the amorphous silicon film is irradiated with a continuously oscillating laser to modify the intended modification area of the amorphous silicon film into a crystallized film. The method is characterized in that a continuously oscillating laser is emitted from a light source, and an optical head is used to process the laser emitted from the light source into a convergent laser beam, so that the laser beam is correspondingly projected onto the intended modification area above the gate line, and the most convergent point of the laser beam is configured to be located inside the amorphous silicon film in the intended modification area, and the optical head is moved in a manner that relatively scans the laser beam in the intended modification area.

[0035] Another form of the present invention relates to a laser annealing method, wherein a gate line is formed on a substrate, and an amorphous silicon film is formed on the upper layer of the gate line in a manner covering the entire substrate. In the laser annealing method, the amorphous silicon film is irradiated with a continuously oscillating laser to modify the intended modification area of the amorphous silicon film into a crystallized film. The method is characterized in that a continuously oscillating laser is emitted from a light source, and an optical head is used to process the laser emitted from the light source into a convergent laser beam, so that the laser beam is correspondingly projected onto the intended modification area above the gate line, and the most convergent point of the laser beam is configured to be located inside the amorphous silicon film in the intended modification area, and the optical head is moved in a manner to relatively scan the laser beam in a specified area including the intended modification area.

[0036] Another form of the present invention relates to a laser annealing method, wherein a gate line is formed on a substrate, and an amorphous silicon film is formed on the upper layer of the gate line in a manner that covers the entire gate line. In the laser annealing method, the amorphous silicon film is irradiated with a continuously oscillating laser to modify the intended modification area of the amorphous silicon film into a crystallized film. The method is characterized in that a continuously oscillating laser is emitted from a light source, and an optical head is used to process the laser emitted from the light source into a convergent laser beam, so that the laser beam is correspondingly projected onto the intended modification area located above the gate line, and an area in the laser beam including a focus and the vicinity of the focus and whose beam profile maintains a top hat shape is configured to overlap with an area inside the amorphous silicon film in the intended modification area, and the optical head is moved in a manner that relatively scans the laser beam within the intended modification area.

[0037] Another form of the present invention relates to a laser annealing method, wherein a gate line is formed on a substrate, and an amorphous silicon film is formed on the upper layer of the gate line in a manner that covers the entire substrate. In the laser annealing method, the amorphous silicon film is irradiated with a continuously oscillating laser to modify the intended modification area of the amorphous silicon film into a crystallized film. The method is characterized in that a continuously oscillating laser is emitted from a light source, and an optical head is used to process the laser emitted from the light source into a convergent laser beam, so that the laser beam is correspondingly projected onto the intended modification area located above the gate line, so that an area in the laser beam including a focus and the vicinity of the focus and whose beam profile maintains a top hat shape is configured to overlap with an area inside the amorphous silicon film in the intended modification area, and the optical head is moved in a manner such that the laser beam relatively scans a specified area including the intended modification area.

[0038] Another form of the present invention relates to a laser annealing method, in which a plurality of gate lines parallel to each other are formed on a substrate, and an amorphous silicon film is formed on the upper layer of the plurality of gate lines in a manner that covers the entirety of the plurality of gate lines. In the laser annealing method, the amorphous silicon film is irradiated with a continuously oscillating laser to modify the intended modification area of the amorphous silicon film into a crystallized film. The method is characterized in that continuously oscillating lasers are emitted from a plurality of light sources respectively, and an optical head is used to process each of the lasers emitted from the plurality of light sources into a convergent laser beam, so that each of the laser beams is projected correspondingly onto the intended modification area above the gate lines in sequence, so that the most convergent point of each laser beam is configured to be located inside the amorphous silicon film in the intended modification area, and the optical head is moved in a manner that relatively scans the laser beam in the intended modification area.

[0039] Another form of the present invention relates to a laser annealing method, in which a plurality of gate lines parallel to each other are formed on a substrate, and an amorphous silicon film is formed on the upper layer of the plurality of gate lines in a manner covering the entire substrate. In the laser annealing method, the amorphous silicon film is irradiated with a continuously oscillating laser to modify the intended modification area of the amorphous silicon film into a crystallized film. The method is characterized in that continuously oscillating lasers are emitted from a plurality of light sources respectively, and an optical head is used to process each of the lasers emitted from the plurality of light sources into a convergent laser beam, so that each of the laser beams is projected correspondingly onto the intended modification area above the gate lines in sequence, so that the most convergent point of each laser beam is configured to be located inside the amorphous silicon film in the intended modification area, and the optical head is moved in a manner to relatively scan the laser beam in a specified area including the intended modification area.

[0040] Another form of the present invention relates to a laser annealing method, in which a plurality of gate lines parallel to each other are formed on a substrate, and an amorphous silicon film is formed on the upper layer of the plurality of gate lines in a manner that covers the entirety of the plurality of gate lines. In the laser annealing method, the amorphous silicon film is irradiated with a continuously oscillating laser to modify the intended modification area of the amorphous silicon film into a crystallized film. The method is characterized in that continuously oscillating lasers are emitted from a plurality of light sources respectively, and an optical head is used to process each of the lasers emitted from the plurality of light sources into a convergent laser beam, so that each of the laser beams is projected correspondingly onto the intended modification area located above the gate lines in sequence, so that the area of each laser beam including the focus and the vicinity of the focus and the beam profile maintaining a top hat shape is configured to overlap with the area inside the amorphous silicon film in the intended modification area, and the optical head is moved in a manner that relatively scans the laser beam in the intended modification area.

[0041] Another form of the present invention relates to a laser annealing method, in which a plurality of gate lines parallel to each other are formed on a substrate, and an amorphous silicon film is formed on the upper layer of the plurality of gate lines in a manner covering the entire substrate. In the laser annealing method, the amorphous silicon film is irradiated with a continuous oscillation laser to modify the intended modification area of the amorphous silicon film into a crystallized film. The method is characterized in that continuously oscillating lasers are emitted from a plurality of light sources respectively, and an optical head is used to process each of the lasers emitted from the plurality of light sources into a convergent laser beam, so that each of the laser beams is projected correspondingly onto the intended modification area located above the gate lines in sequence, so that the area including the focus and the vicinity of the focus in each laser beam and the beam profile maintaining a top hat shape is configured to overlap with the area inside the amorphous silicon film in the intended modification area, and the optical head is moved in a manner to relatively scan the laser beam in a specified area including the intended modification area.

[0042] Effects of the invention

[0043] The laser annealing apparatus and the laser annealing method of the present invention have the effect of effectively crystallizing the amorphous silicon film only in the modification target region without thermally damaging the substrate and gate lines disposed below the amorphous silicon film. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a cross-sectional explanatory diagram showing a method for manufacturing a TFT array using the laser annealing apparatus according to the first embodiment of the present invention.

[0045] Figure 2 It is a diagram schematically showing the configuration of a laser annealing apparatus according to a first embodiment of the present invention.

[0046] Figure 3 It is a plan view illustrating a method for manufacturing a TFT array using the laser annealing apparatus according to the first embodiment of the present invention.

[0047] Figure 4-1 It is a plan view illustrating a laser annealing method using the laser annealing apparatus according to the first embodiment of the present invention.

[0048] Figure 4-2 It is a plan view illustrating a method for manufacturing a TFT array in a state where the beam pitch is changed by rotating the optical head in the laser annealing apparatus according to the first embodiment of the present invention.

[0049] Figure 5 It is a diagram schematically showing the configuration of a laser annealing apparatus according to a second embodiment of the present invention.

[0050] Figure 6 It is a diagram schematically showing the configuration of a laser annealing apparatus according to a third embodiment of the present invention.

[0051] Figure 7 It is a diagram schematically showing the configuration of a laser annealing apparatus according to a fourth embodiment of the present invention.

[0052] Figure 8 It is a side view showing the main part of a laser annealing apparatus according to a fourth embodiment of the present invention.

[0053] Figure 9 It is a schematic structural diagram showing a laser annealing apparatus according to a fifth embodiment of the present invention.

[0054] Figure 10 It is a diagram schematically showing the configuration of a laser annealing apparatus according to a sixth embodiment of the present invention.

[0055] Figure 11 It is a diagram showing the configuration of an imaging optical system in a laser annealing apparatus according to a sixth embodiment of the present invention.

[0056] Figure 12 It is a schematic diagram showing the configuration of a laser annealing apparatus according to a seventh embodiment of the present invention.

[0057] Figure 13 This is an explanatory diagram showing a region A including the focal point and the vicinity of the focal point of the laser beam in the laser annealing apparatus according to the eighth embodiment of the present invention, where the energy density profile maintains a top-hat shape.

[0058] Figure 14-1 Yes Figure 13 An explanatory diagram of the relationship between the radial position of the laser beam and the power density in the region (4).

[0059] Figure 14-2 Yes Figure 13 An explanatory diagram of the relationship between the radial position of the laser beam and the power density in the region (2).

[0060] Figure 14-3 Yes Figure 13 An explanatory diagram of the relationship between the radial position of the laser beam and the power density in the region (1).

[0061] Figure 14-4 Yes Figure 13 An explanatory diagram of the relationship between the radial position of the laser beam and the power density in the region (3).

[0062] Figure 14-5 Yes Figure 13 An explanatory diagram of the relationship between the radial position of the laser beam and the power density in the region (5).

[0063] Description of Reference Numerals

[0064] D1, D2 light intensity sensors, LD semiconductor laser, 1, 1A, 1B, 1C, 1D, 1E, 1F laser annealing device, 2 light source unit, 3 optical head, 10 substrate (laser annealing treated substrate), 11 glass substrate (substrate), 12 gate line, 13 silicon nitride film, 14 silicon oxide film, 15a amorphous silicon film, 21 coupling lens, 22 optical fiber, 31 optical fiber array, 32, 32B imaging optical system, 33 first lens, 34 second lens, 35 beam splitter, 36 side lens, 37 mask, 37A opening, 38 imaging optical system, 39 actuator. DETAILED DESCRIPTION

[0065] The following describes in detail the laser annealing apparatus and laser annealing method according to embodiments of the present invention, based on the accompanying drawings. However, please note that the drawings are schematic and that the number of components, their dimensions, dimensional ratios, and shapes may differ from those in reality. Furthermore, the drawings may also include portions with different dimensional relationships, ratios, and shapes.

[0066] [First embodiment]

[0067] (Structure of Laser Annealing Apparatus)

[0068] like Figure 1 and Figure 2 As shown, the laser annealing apparatus 1 of this embodiment includes a light source unit 2 , an optical head 3 , a substrate transport mechanism (not shown) for transporting a substrate 10 , and a displacement meter (not shown).

[0069] The light source unit 2 includes a plurality of semiconductor lasers LD (LD1 to LDn) serving as light sources for oscillating a continuously oscillating laser (CW laser). Here, the term "continuously oscillating laser (CW laser)" encompasses a concept that also includes so-called quasi-continuous oscillation, which continuously irradiates a target area with laser light. Specifically, the laser may be a pulsed laser or a quasi-continuous oscillation laser in which the pulse interval is shorter than the cooling time of the heated silicon thin film (amorphous silicon film) (the film is irradiated by the next pulse before hardening). Various lasers, such as semiconductor lasers, solid-state lasers, liquid lasers, and gas lasers, may be used as laser sources.

[0070] In addition, in this embodiment, as the backup R of the semiconductor laser LD, for example, semiconductor lasers LD100 to LDn are provided.

[0071] The light source unit 2 includes the aforementioned plurality of semiconductor lasers LD, a drive circuit 20, and a plurality of coupling lenses 21. The drive circuit 20 is connected to each of the plurality of semiconductor lasers LD to drive each of the semiconductor lasers LD.

[0072] The coupling lens 21 is connected to the emission side of each semiconductor laser LD.

[0073] One end of an optical fiber 22 serving as a waveguide is connected to each coupling lens 21. In this embodiment, a multimode optical fiber is used as the optical fiber 22.

[0074] The optical head 3 includes an optical fiber array 31 and an imaging optical system 32. The optical fiber array 31 is connected to the other end of the optical fiber 22. In this embodiment, the output ends of the optical fibers 22 connected to the optical fiber array 31 are arranged in a row along a straight line on the output-side end surface of the optical fiber array 31.

[0075] The imaging optical system 32 includes at least a first lens 33 on the incident side and a second lens 34 on the exit side. Figure 2 As shown, the laser light emitted from the optical fiber array 31 is incident on the imaging optical system 32. Figure 1 As shown, in the optical head 3, the laser is processed into a laser beam LBcw that converges to a spot portion F toward the downstream side (rear side). Figure 4-1 As shown, on the exit side of the optical head 3, laser beams LBcw are emitted from positions arranged at a pitch P1 along a straight line. This pitch P1 is set to be the same as the pitch of the gate lines 12 described later. It should be noted that in this embodiment, the arrangement direction of the laser beams LBcw is set to be perpendicular to the extension direction of the gate lines 12 described later.

[0076] It should be noted that a displacement meter (not shown) is provided on the side of the optical head 3 to compensate for positional deviation between the optical head 3 and the substrate 10. An autofocus function is provided that automatically adjusts the focus of the laser beam LBcw emitted from the optical head 3 based on the data on the positional deviation between the optical head 3 and the substrate 10 detected by the displacement meter. It should be noted that in this embodiment, a displacement meter is used as the autofocus mechanism, but this is not limiting, and various well-known technologies can be used.

[0077] It should be noted that in this embodiment, the laser beam LBcw has a top-hat shape, with a square cross-section in a direction perpendicular to the optical axis. It should be noted that the cross-sectional shape of the laser beam LBcw can also be rectangular, hexagonal, or other shapes. To achieve such a cross-sectional shape for the laser beam LBcw, the core of the optical fiber 22 can be configured to have a square, rectangular, hexagonal, or other cross-sectional shape.

[0078] The substrate transport mechanism (not shown) transports the laser annealed substrate 10 in the scanning direction at an arbitrary speed.

[0079] like Figure 1As shown, substrate 10, which is a substrate to be laser annealed, is primarily composed of a glass substrate 11. Multiple gate lines 12 patterned with copper (Cu), other metal wiring patterns, a silicon nitride film (Si3N4) 13, a silicon oxide film (SiO2) 14, and an amorphous silicon film 15a, which is a film to be laser annealed, are sequentially stacked on this glass substrate 11. Multiple gate lines 12 are arranged parallel to one another. As described above, the spacing between gate lines 12 is set to pitch P1.

[0080] The gate line 12 includes a portion that serves as the gate electrode of a TFT formed in each pixel region (not shown). For example, the gate line 12 may have a thickness of 200 to 700 nm, the silicon nitride film 13 may have a thickness of approximately 300 nm, the silicon oxide film 14 may have a thickness of 50 to 100 nm, and the amorphous silicon film 15a may have a thickness of approximately 50 nm.

[0081] In the present embodiment, the beam diameter size of the laser beam LBcw irradiated onto the surface of the amorphous silicon film 15 a is set to an arbitrary size of, for example, 5 μm or more and 300 μm or less.

[0082] The beam diameter range is defined as the size of the laser beam LBcw's irradiation surface that fits within the semiconductor active region (area to be modified) of the TFT. The diameter of the laser beam LBcw's irradiation surface is preferably greater than or equal to 10 μm and less than or equal to 100 μm.

[0083] In the present embodiment, the scanning speed at which the laser beam LBcw relatively scans the amorphous silicon film 15 a is preferably 200 mm to 500 mm / second, but the present invention is not limited thereto.

[0084] like Figure 3 As shown, under the above-mentioned conditions, the laser beam LBcw is irradiated onto the area to be modified in the amorphous silicon film 15a along the extending direction of the gate line 12, thereby locally modifying the amorphous silicon film 15a into a quasi-single-crystalline silicon film 15La. It should be noted that the area where the quasi-single-crystalline silicon film 15La is formed coincides with the area to be modified.

[0085] According to the laser annealing apparatus 1 of this embodiment, the point F with high power density in the laser beam LBcw is located inside the amorphous silicon film 15a, so a large amount of heat is supplied to the amorphous silicon film 15a. Moreover, most of the heat is dissipated from the point F toward the side ( Figure 1The laser beam (in the direction of arrow h in FIG. 1 ) propagates within the amorphous silicon film 15a. On the rear side (lower side) of the dot portion F, the beam diffuses, reducing the power density of the light reaching the underlying silicon oxide film 14 and the like. This reduces overheating of the lower layer of the amorphous silicon film 15a. Therefore, the laser annealing apparatus 1 of this embodiment can prevent damage to the gate lines 12, other wiring patterns, the glass substrate 11, and the like due to overheating.

[0086] According to the laser annealing apparatus 1 of this embodiment, even when the amorphous silicon film 15 a is formed to cover the entire gate lines 12 , no damage occurs to the gate lines 12 , other wirings, or the glass substrate 11 .

[0087] Furthermore, according to the laser annealing apparatus 1 of the present embodiment, it is sufficient to irradiate only the region to be reformed, which is to become the channel semiconductor layer of the TFT, with the laser beam LBcw, thereby improving energy efficiency.

[0088] It should be noted that the aforementioned spot portion F may have a limited width (margin) along the optical axis, as a range within which the power density maintains the top-hat shape. This is because within this range, uniform annealing can be performed, maintaining a state where energy is concentrated in the amorphous silicon film 15a. The range within which the power density at the spot portion F maintains the top-hat shape will be described later in the eighth embodiment.

[0089] In the present invention, the beam diameter of laser beam LBcw can be considered to be the diameter of the flat portion of the top-hat shape. This is because, as long as uniform annealing can be performed on the target area for modification, the power density decreases sharply outside the flat portion of the top-hat shape of laser beam LBcw, thereby simultaneously avoiding thermal damage and improving energy efficiency.

[0090] In addition, as long as the amorphous silicon film 15a is formed on the entire surface of the substrate and the beam diameter (the width of the irradiation area) is much smaller than the distance between the gate lines, the beam diameter can be larger than the area to be modified. This is because the heat generation is concentrated in the amorphous silicon 15a, which can greatly improve the energy utilization efficiency compared to the conventional linear beam annealing process. Here, the beam diameter is much smaller than the distance between the gate lines, which means that the beam diameter is less than 1 / 10 of the distance between the gate lines. Under such conditions, the irradiation area of the laser beam LBcw when it is exposed along the width direction of the gate lines is defined as the specified area including the area to be modified in the present invention.

[0091] [Modification of the First Embodiment]

[0092] Figure 4-2The optical head 3 of a modified example of the laser annealing apparatus 1 according to the first embodiment of the present invention is shown. In this modified example, the optical head 3 is configured to be rotationally driven by a rotation drive unit (not shown). It should be noted that the basic structure of the optical head 3 in this modified example is the same as that of the first embodiment described above.

[0093] In this modification, the pitch P2 between the gate lines 12 is larger than Figure 4-1 The pitch P1 of the gate lines 12 shown is short and can be applied. Figure 4-2 As shown, the optical head 3 is rotated and adjusted so that the laser beam LBcw corresponds to a plurality of gate lines 12, thereby being able to reliably irradiate the laser beam LBcw to the modification target area of the amorphous silicon film 15a above the gate lines 12. Figure 4-2 As shown, when the optical head 3 is rotated and moved obliquely to scan relative to the substrate 10, the timing of irradiating the laser beam LBcw to the predetermined area for modification is staggered in sequence according to each gate line 12. Therefore, it is sufficient to set the output timing to the semiconductor laser LD to be delayed in sequence through the driving circuit 20.

[0094] According to this modification, the pitch between the columns irradiated with the laser beam LBcw can be changed by rotating the optical head 3. Therefore, a laser annealing apparatus that can be applied even when the pitch of the gate lines 12 on the substrate is changed can be realized.

[0095] [Laser annealing method]

[0096] Next, the laser annealing method of this embodiment will be described. The laser annealing method is a laser annealing method for forming a quasi-single-crystal silicon film 15La in a region to be reformed on a substrate 10 using a laser annealing apparatus 1 .

[0097] First, in the laser annealing method, as Figure 1 As shown, a substrate 10 is prepared. In this substrate 10, a plurality of gate lines 12 parallel to each other are formed on a glass substrate 11, and an amorphous silicon film 15a is formed on the plurality of gate lines 12 so as to cover the entire gate lines 12.

[0098] Next, the substrate 10 is placed on a substrate conveying mechanism not shown in the figure, so that the semiconductor laser LD emits continuously oscillating laser light respectively, and the laser is processed into a convergent laser beam LBcw using the optical head 3, and each laser beam LBcw is projected in sequence into the unshown predetermined modification area located above the gate line 12.

[0099] At this time, the most convergent point F of the laser beam LBcw is arranged to be located inside the amorphous silicon film 15a in the region to be reformed.

[0100] Then, the substrate 10 is moved by a substrate transport mechanism (not shown) to scan the laser beam LBcw relatively in the region to be reformed along the direction in which the gate line 12 extends. As a result, the region to become the channel semiconductor layer of the TFT can be reformed into the quasi-single-crystal silicon film 15La.

[0101] In the laser annealing method of this embodiment, the quasi-single-crystal silicon film 15La can be formed only in the region where the channel semiconductor layer of the TFT is to be formed, thereby enabling annealing with high energy efficiency. Therefore, this laser annealing method can achieve significant cost reduction. Furthermore, in conventional annealing methods using a linear beam based on an excimer laser, laser irradiation is performed by smearing the entire region of the amorphous silicon film with the linear beam to crystallize it, thereby creating a seam in the irradiated region of the amorphous silicon film. Consequently, the mobility of the channel semiconductor layer in the seam region and the channel semiconductor layer in other regions differ, resulting in uneven mobility in the channel semiconductor layer of the entire TFT substrate. In contrast, in the laser annealing method of this embodiment, no seam is created in the irradiated region, thereby enabling the mobility of the channel semiconductor layer to be uniform.

[0102] Furthermore, in the laser annealing method of this embodiment, thermal damage to the gate lines 12 , the glass substrate 11 , and the like is not caused, and thus, the TFT substrate can be manufactured with a high yield.

[0103] [Second embodiment]

[0104] Figure 5 1A is a schematic diagram showing the configuration of a laser annealing apparatus 1A according to a second embodiment of the present invention.

[0105] This embodiment is characterized in that a light quantity sensor D1 is provided to detect the light quantity of each of the plurality of laser beams LBcw. The remaining configuration of this embodiment is the same as that of the laser annealing apparatus 1 of the first embodiment, and therefore description thereof will be omitted.

[0106] The light quantity sensor D1 is arranged behind the optical head 3 and can be sequentially moved toward the spot F of the laser beam LBcw. The light quantity sensor D1 is set to avoid the adjacent laser beam LBcw from entering when detecting the light quantity of one laser beam LBcw.

[0107] In the present embodiment, data detected by the light amount sensor D1 is fed back to the drive circuit 20 to adjust the output of the semiconductor laser LD serving as the light source of the laser beam LBcw.

[0108] In this embodiment, the light intensity of each laser beam LBcw is adjusted before the laser annealing process, thereby making the output (light intensity) of these laser beams LBcw uniform. Therefore, the laser annealing apparatus 1A of this embodiment can make the electrical characteristics of the channel semiconductor layers of each TFT uniform.

[0109] [Third embodiment]

[0110] Figure 6 This is a schematic diagram of a laser annealing apparatus 1B according to a third embodiment of the present invention. The laser annealing apparatus 1B of this embodiment includes a beam splitter 35 in the optical path within an imaging optical system 32B. A side lens 36 and a light intensity sensor D2 are disposed to the side of the beam splitter 35. In this embodiment, the laser beam LBcw reflected by the beam splitter 35 is configured to pass through the side lens 36 and enter the light intensity sensor D2. The remaining configuration of the laser annealing apparatus 1B of this embodiment is the same as that of the first embodiment described above.

[0111] In this embodiment, the data detected by the light quantity sensor D2 is fed back to the drive circuit 20 to adjust the output of the semiconductor laser LD serving as the light source of the laser beam LBcw. In this embodiment, the output of each semiconductor laser LD can be adjusted while the laser annealing apparatus 1B is in operation.

[0112] [Fourth embodiment]

[0113] Figure 7 1C is a schematic diagram showing the structure of a laser annealing apparatus according to a fourth embodiment of the present invention. Figure 8 This is a side view of the main parts of the laser annealing device 1C. The laser annealing device 1C of this embodiment allows the laser light emitted from the optical fiber array 31 to pass through the first lens 33 and be reflected downward (laterally) by a scanning mirror SM such as a galvanometer mirror. The laser beam LBcw reflected by the scanning mirror SM passes through the second lens 34 disposed below and is irradiated toward the substrate side. Figure 8 As shown in FIG. 1 , the scanning mirror SM is set to be rotatable and adjustable in the direction of arrow A in order to change the degree of inclination.

[0114] Furthermore, by rotating the scanning mirror SM, the irradiation position of the laser beam LBcw and the depth position of the spot F from the surface of the amorphous silicon film 15a in the film thickness direction can be adjusted.

[0115] [Fifth embodiment]

[0116] Figure 9This is a schematic diagram of a laser annealing apparatus 1D according to a fifth embodiment of the present invention. This embodiment includes an imaging optical system 32D configured by placing a mask 37 having an opening 37A at the pupil position of the imaging optical system 32 of the laser annealing apparatus 1A according to the second embodiment. The remaining configuration of the laser annealing apparatus 1D according to this embodiment is the same as that of the laser annealing apparatus 1A according to the second embodiment.

[0117] According to this embodiment, the pattern of the laser beam LBcw passing through the imaging optical system 32D can be changed using the mask 37. Since the light quantity sensor D1 is also provided in this embodiment, the light quantity sensor D1 can detect the light quantity of each laser beam LBcw with a changed pattern.

[0118] [Sixth embodiment]

[0119] Figure 10 It is a schematic diagram of the structure of a laser annealing apparatus 1E according to a sixth embodiment of the present invention. Figure 11 1E is a schematic diagram of the structure of the imaging optical system 38 in the laser annealing apparatus 1E.

[0120] like Figure 10 As shown, similar to the first embodiment, the laser annealing apparatus 1E of this embodiment includes an optical fiber array 31 and an imaging optical system 38 as an optical head 3. The optical fiber array 31 is connected to the other end of the optical fiber 22. The output ends of the optical fibers 22 are arranged in a row along a straight line on the output-side end surface of the optical fiber array 31.

[0121] In this embodiment, the imaging optical system 38 is a telecentric optical system. Furthermore, the optical fiber array 31 is displaced along the optical axis by an actuator 39. In this embodiment, during autofocusing of the laser annealing apparatus 1E, only the optical fiber array 31 is moved along the optical axis by the actuator 39. At this time, the light source unit 2 and the imaging optical system 38 do not move.

[0122] like Figure 11 As shown, in this embodiment, the imaging optical system 38 comprises a telecentric optical system composed of a plurality of optical components L1 to L14, such as lenses, arranged sequentially along the optical axis. With this telecentric optical system 38, when focusing on the substrate 10, the actuator 39 only needs to move the lightweight optical fiber array 31, thereby achieving highly responsive autofocus performance.

[0123] Furthermore, since the imaging optical system 38 is formed of a telecentric optical system, there is an advantage in that there is no deviation of the image relative to the substrate 10 and the pitch of the irradiation positions of the plurality of laser beams LBcw on the surface of the substrate 10 does not change.

[0124] Note that a piezoelectric actuator as a positioning element utilizing the piezoelectric effect can be applied as the actuator 39. The piezoelectric actuator can accurately perform positioning from an extremely small range of nanometers to several hundred micrometers.

[0125] Furthermore, piezoelectric actuators are made of ceramic, making them very rigid and capable of generating large forces. Furthermore, piezoelectric actuators are compact and energy-efficient. It should be noted that in this embodiment, a piezoelectric actuator is used as actuator 39, but other drive mechanisms such as linear motors may also be used.

[0126] In the laser annealing apparatus 1E, it is only necessary to move the lightweight optical fiber array 31 , so the load on the actuator 39 is small, and a rapid autofocus function can be provided.

[0127] [Seventh embodiment]

[0128] Figure 12 This is a schematic diagram showing the structure of a laser annealing apparatus 1F according to a seventh embodiment of the present invention. In this embodiment, the apparatus comprises a single semiconductor laser LD as a light source, a coupling lens 21, a single optical fiber 22, a single optical head 3, and a substrate transport mechanism (not shown) for transporting a substrate 10.

[0129] As in the above-mentioned embodiments, the semiconductor laser LD oscillates a continuous wave laser (CW laser). A coupling lens 21 is connected to the emission side of the semiconductor laser LD. One end of an optical fiber 22 serving as a waveguide is connected to the coupling lens 21. In this embodiment, a square optical fiber, for example, is used as the optical fiber 22.

[0130] The optical head 3 includes a first lens 33 on the incident side and a second lens 34 on the exit side as an imaging optical system. Figure 12 As shown, laser light emitted from the other end of the optical fiber 22 is incident on the optical head 3. In the optical head 3, the laser light is processed into a laser beam LBcw that converges toward the downstream side (rear side) at a spot portion F. In this embodiment, the spot portion F is also set so as to be located inside the amorphous silicon film (inside in the depth direction).

[0131] In this embodiment, the laser beam LBcw has a top-hat shape, with a square cross-section in a direction perpendicular to the optical axis. It should be noted that the cross-section of the laser beam LBcw can also be rectangular, hexagonal, or other shapes. To achieve such a cross-sectional shape for the laser beam LBcw, the core of the optical fiber 22 can be configured to have a square, rectangular, hexagonal, or other cross-sectional shape.

[0132] The substrate transport mechanism (not shown) is similar to the above-described embodiments and is provided with a mechanism for transporting the substrate 10 to be subjected to laser annealing in the scanning direction at an arbitrary speed. Therefore, the substrate 10 is transported while the position of the optical head 3 is fixed, thereby causing the laser beam LBcw to scan relative to the substrate 10.

[0133] According to the laser annealing apparatus 1F of this embodiment, the spot F with high power density in the laser beam LBcw is located inside the amorphous silicon film, thereby supplying a large amount of heat to the amorphous silicon film in a concentrated manner. Furthermore, most of the heat is transferred laterally from the spot F within the amorphous silicon film. On the rear side (lower side) of the spot F, the beam diffuses, reducing the power density of the light reaching the underlying silicon oxide film, etc., thereby suppressing overheating of the lower layer of the amorphous silicon film. Therefore, the laser annealing apparatus 1F can prevent damage to gate lines, other wiring patterns, glass substrates, etc. due to overheating.

[0134] It should be noted that the laser annealing method of this embodiment is a method in which a continuous oscillation laser is emitted from a single light source toward the amorphous silicon film above the gate line, irradiating the laser beam to a single area to be modified. The effect of the laser beam LBcw is the same as that of the laser annealing method of the first embodiment described above.

[0135] [Eighth Embodiment]

[0136] Figure 13 The basic principles of a laser annealing apparatus and a laser annealing method according to an eighth embodiment of the present invention will be described.

[0137] In the first to seventh embodiments described above, the laser beam LBcw is scanned while the most convergent point F of the laser beam LBcw is located inside the amorphous silicon film 15a in the region to be reformed. Figure 13 As shown in FIG. 1 , the laser beam LBcw is scanned within the region to be modified while the region A including the focus and the vicinity of the focus of the laser beam LBcw and the beam profile maintaining a top-hat shape overlaps with the region inside the amorphous silicon film 15a. That is, in the laser annealing apparatus of this embodiment, as long as Figure 13 The amorphous silicon 15a shown may be in a state where it overlaps with the region A of the laser beam LBcw.

[0138] like Figure 13 As shown, region A includes (1), (2) and (3) in laser beam LBcw. Figure 14-3 express Figure 13 The relationship between the radial position and power density of the laser beam in the range of (1). Figure 13 As shown, the area of (1) is the area of approximately the focal depth, as shown in Figure 14-3As shown in FIG, a typical top hat shaped beam profile is shown. Although the area (2) is located closer to the focus than the area (1), Figure 14-2 The laser profile shown can be seen as a top hat shaped area. Although the area (3) is located behind the focus of the area (1), Figure 14-4 The laser profile shown can be seen as a top-hat shaped area.

[0139] The area of (4) is located closer to the front than the area of (2), such as Figure 14-1 As shown in FIG, the laser profile cannot be seen as a top hat shape. The area (5) is located behind the area (3), as shown in FIG. Figure 14-5 As shown, the laser profile cannot be seen as a top hat shape. Therefore, in this embodiment, Figure 13 The region A shown is defined as a region where the beam profile maintains a top-hat shape. Note that the region A may be appropriately set according to the conditions of the optical head 3 and the like.

[0140] like Figure 14-3 As shown, the region (1) has sufficient energy density required for annealing the amorphous silicon 15a and has a flat portion width dimension that enables annealing of the desired region. Figure 14-2 and Figure 14-4 As shown in , the regions (2) and (3) are similar to the characteristics of the region (1), but as Figure 14-1 and Figure 14-5 As shown, the energy density in the regions (4) and (5) is insufficient, and the width of the flat portion for annealing the desired region is narrow, so these regions are not suitable for local annealing of the amorphous silicon 15a.

[0141] The eighth embodiment of the present invention has been described above, but the other structures are the same as those of the laser annealing apparatus and the laser annealing method of the first embodiment described above.

[0142] In this embodiment, for example, when the amorphous silicon 15a is located Figure 13 In the case of the region (2) shown, the focal position appears to be on the substrate, wiring, etc. below the amorphous silicon 15a, but most of the light is absorbed by the amorphous silicon 15a, so there is no thermal damage to the substrate, wiring, etc. below the amorphous silicon 15a. Therefore, according to this embodiment, the setting of the conditions of the optical head 3 and the like becomes easier and the device cost can be reduced.

[0143] (Other Embodiments)

[0144] While the embodiments of the present invention have been described above, it should not be understood that the description and drawings, which constitute part of the disclosure of the embodiments, limit the present invention. Based on this disclosure, various alternative embodiments, examples, and operational techniques will become apparent to those skilled in the art.

[0145] In the above embodiment, a top-hat-shaped laser beam LBcw is used, but a ring-shaped laser beam LBcw may also be used. By using such a ring-shaped laser beam LBcw, there is an advantage that the contour of the crystallized film formed in the modification target area can also be reliably crystallized.

[0146] In each of the above-mentioned embodiments, the other end of the optical fiber 22 is arranged in a straight line in the output end face of the optical fiber array 31, but as long as the laser beam LBcw can be irradiated corresponding to the equally spaced gate lines 12, the other end of the optical fiber 22 does not have to be arranged in a straight line.

[0147] In the first to sixth embodiments described above, the spacing of the plurality of laser beams LBcw is set to be the same as the spacing of the gate lines, and the laser beams LBcw are scanned in the direction along the gate lines 12. However, as long as the spacing of the laser beams LBcw is set to an integer multiple of the spacing of the predetermined modified area of the TFT formed along the gate lines 12, the laser beams LBcw can also be scanned in a direction orthogonal to the gate lines 12.

Claims

1. A laser annealing device, A plurality of gate lines parallel to each other are formed on a substrate, and an amorphous silicon film is formed on the upper layer of the plurality of gate lines in a manner of covering the entire plurality of gate lines. The laser annealing device irradiates the amorphous silicon film with a continuous wave laser to transform a region of the amorphous silicon film to be transformed into a crystallized film, wherein: The laser annealing device comprises: a plurality of light sources each emitting a continuous oscillation laser beam; and An optical head, which processes each of the laser beams emitted from the plurality of light sources into a convergent laser beam, wherein each of the laser beams can be sequentially projected onto the predetermined modification area above the gate line. The optical head relatively scans the laser beams in the region to be modified in a state where the most convergent point of each laser beam is located inside the amorphous silicon film in the region to be modified. The laser beam emitted from the optical head is projected onto the surface of the amorphous silicon film along a predetermined straight line at a constant pitch. The optical head is capable of rotationally moving so that a pitch between the plurality of laser beams is equal to a pitch between the gate lines.

2. A laser annealing device, A plurality of gate lines parallel to each other are formed on a substrate, and an amorphous silicon film is formed on the upper layer of the plurality of gate lines in a manner of covering the entire plurality of gate lines. The laser annealing device irradiates the amorphous silicon film with a continuous wave laser to transform a region of the amorphous silicon film to be transformed into a crystallized film, wherein: The laser annealing device comprises: a plurality of light sources each emitting a continuous oscillation laser beam; and An optical head, which processes each of the laser beams emitted from the plurality of light sources into a convergent laser beam, wherein each of the laser beams can be sequentially projected onto the predetermined modification area above the gate line. The optical head relatively scans the laser beams over a predetermined area including the area to be modified, in a state where the most convergent point of each laser beam is located inside the amorphous silicon film in the area to be modified. The laser beam emitted from the optical head is projected onto the surface of the amorphous silicon film along a predetermined straight line at a constant pitch. The optical head is capable of rotationally moving so that a pitch between the plurality of laser beams is equal to a pitch between the gate lines.

3. A laser annealing device, A plurality of gate lines parallel to each other are formed on a substrate, and an amorphous silicon film is formed on the upper layer of the plurality of gate lines in a manner of covering the entire plurality of gate lines. The laser annealing device irradiates the amorphous silicon film with a continuous wave laser to transform a region of the amorphous silicon film to be transformed into a crystallized film, wherein: The laser annealing device comprises: a plurality of light sources each emitting a continuous oscillation laser beam; and An optical head, which processes each of the laser beams emitted from the plurality of light sources into a convergent laser beam, wherein each of the laser beams can be sequentially projected onto the predetermined modification area above the gate line. The optical head relatively scans the laser beam in the area to be modified, in a state where an area including the focal point and the vicinity of the focal point of each laser beam and where the beam profile maintains a top-hat shape overlaps with an area inside the amorphous silicon film in the area to be modified. The laser beam emitted from the optical head is projected onto the surface of the amorphous silicon film along a predetermined straight line at a constant pitch. The optical head is capable of rotationally moving so that a pitch between the plurality of laser beams is equal to a pitch between the gate lines.

4. A laser annealing device, A plurality of gate lines parallel to each other are formed on a substrate, and an amorphous silicon film is formed on the upper layer of the plurality of gate lines in a manner covering the entire substrate. The laser annealing device irradiates the amorphous silicon film with a continuous wave laser to transform a region of the amorphous silicon film to be transformed into a crystallized film, wherein: The laser annealing device comprises: a plurality of light sources each emitting a continuous oscillation laser beam; and An optical head, which processes each of the laser beams emitted from the plurality of light sources into a convergent laser beam, wherein each of the laser beams can be sequentially projected onto the predetermined modification area above the gate line. The optical head relatively scans the laser beam over a predetermined area including the area to be modified, in a state where an area including the focal point and the vicinity of the focal point of each laser beam and where the beam profile maintains a top-hat shape overlaps with an area inside the amorphous silicon film in the area to be modified. The laser beam emitted from the optical head is projected onto the surface of the amorphous silicon film along a predetermined straight line at a constant pitch. The optical head is capable of rotationally moving so that a pitch between the plurality of laser beams is equal to a pitch between the gate lines.

Images