TW202036729A - Laser annealing method and laser annealing device - Google Patents

Abstract

According to the present invention, a continuously oscillated laser beam emitted from continuously oscillated laser is used as a laser beam to set, in a beam spot LBS, the energy density of a downstream-side portion in the movement direction (reverse direction of substrate movement direction T), in which the beam spot LBS is relatively moved, to be higher than the energy density of an upstream-side portion in the movement direction thereof; and the beam spot LBS is projected onto an end edge section in a modification planned region to form a seed crystal region, and then the beam spot LBS is moved in the movement direction to modify the entire surface of the modification planned region into a crystallized silicon film from the seed crystal region serving as a start point.

Description

Laser annealing method and laser annealing device

The invention relates to a laser annealing method and a laser annealing device.

A thin film transistor (TFT: Thin Film Transistor) is used as a switching element for actively driving a thin display (FPD: Flat Panel Display). As for the material of the semiconductor layer of the thin film transistor (hereinafter referred to as TFT), amorphous silicon (a-Si: amorphous Silicon) or polycrystalline silicon (p-Si: polycrystalline silicon) is used.

The mobility (μ), an index of the mobility of amorphous silicon-based electrons, is low. Therefore, in amorphous silicon, it cannot fully correspond to the high mobility required in FPD where high density and high definition are more advanced. Therefore, as for the switching element in the FPD, it is preferable to form the channel semiconductor layer with polysilicon whose mobility is much higher than that of amorphous silicon. Regarding the method of forming polysilicon film, there is an Excimer Laser Annealing (ELA: Excimer Laser Annealing) device using an excimer laser to irradiate the amorphous silicon film with laser light to recrystallize the amorphous silicon to form polysilicon Methods.

With regard to the conventional laser annealing method, it is known that in the irradiated area, the technique of using a pulsed laser beam of excimer laser light generated by an excimer laser annealing (hereinafter referred to as ELA) device (refer to Patent Document 1).

In this laser annealing method, the area to be treated is irradiated with a high-energy portion that generates a pulsed laser beam. After the high-energy portion passes, the laser beam with a smaller energy is sequentially performed. Irradiation of the low-energy part of the beam. In this laser annealing method, the low-energy part is irradiated to achieve the crystallization of the residual poor crystallization area caused by the high-energy part.

As for other laser annealing methods, it has been proposed that the laser beam of the pulsed laser light obtained by the ELA device has an energy distribution along the scanning direction. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] JP 2002-313724 A

(The problem to be solved by the invention)

However, the ELA device is a gas laser using a special gas, which has the problem of high equipment cost and maintenance cost. In addition, the ELA device has a strong output, and there is a problem that it is difficult to match the phase of the laser light (coherence) or maintain the output in a constant state.

In the laser annealing method disclosed in the aforementioned Patent Document 1, since a large number of light sources are required, there is a problem of higher cost. In addition, the particle size of polycrystalline silicon crystals formed by pulsed light irradiation of excimer lasers is about several 10 to 350 nm. In this degree of crystal grain size, higher mobility cannot be satisfied. At present, the TFT of the driving circuit that turns on/off the pixel transistor in the FPD is also required to have high mobility in the channel semiconductor layer area. In addition, in FPD, with the increase in size, resolution, and speed of dynamic image characteristics, high mobility is also urgently desired in TFTs, which are switching elements of pixels.

The present invention was made in view of the above-mentioned problems, and its object is to provide a polycrystalline silicon film or a pseudo-single-crystal silicon film with high mobility that can be stably formed in a necessary area, and the laser irradiation conditions of the substrate to be processed can be controlled well. A laser annealing method and a laser annealing device that achieve a substantial cost reduction. (Means to solve the problem)

In order to solve the above-mentioned problems and achieve the objective, the aspect of the present invention is a laser annealing method, which is to modify a predetermined region of an amorphous silicon film, move the beam spot of the laser light relatively, and perform the above-mentioned amorphous silicon film. The laser annealing method for upgrading to crystalline silicon by laser annealing is characterized in that the laser light is a continuous oscillating laser light emitted from a continuous oscillating laser, and the beam spot is relatively moved among the beam spots The energy density of the downstream part of the moving direction of the beam spot is set to be higher than the energy density of the upstream part of the moving direction of the beam spot, and the beam spot is projected on the edge of the predetermined modification area. After the seed crystal area is formed, the beam spot is moved toward the moving direction, and the entire area of the predetermined modification area is modified into a crystalline silicon film using the seed crystal area as a starting point.

In the above aspect, it is preferable to stop the emission of the continuous oscillation laser light after forming the seed crystal region, and then start the emission of the continuous oscillation laser light within a predetermined time to move the beam spot .

In the above aspect, it is preferable that after the seed crystal region is formed, the beam spot is continuously moved while maintaining the state of emitting the continuously oscillating laser light.

In the above aspect, it is preferable that the energy density of the upstream portion of the beam spot gradually decreases toward the upstream side of the moving direction.

In terms of the above aspect, the aforementioned continuous oscillation laser-based semiconductor laser is preferable.

In the above aspect, it is preferable to set the energy density of the downstream part of the beam spot to be higher than the threshold value for melting the amorphous silicon film. The energy density in the upstream portion is set toward the upstream side of the aforementioned movement direction, and gradually decreases by the aforementioned threshold value.

In the above aspect, it is preferable that the beam spot is formed into a slender rectangular shape, and the beam spot is projected onto the beam spot so that the long axis of the beam spot becomes a direction orthogonal to the moving direction. Amorphous silicon film.

In another aspect of the present invention, it is a laser annealing device, which moves the beam spot relative to the amorphous silicon film formed on the substrate to be processed, and performs laser annealing on the amorphous silicon film The laser annealing device modified to crystalline silicon is characterized by: a base on which the substrate to be processed is disposed; and a laser beam irradiation section for the treated substrate disposed on the base. The substrate is relatively moved, provided with a continuous oscillation laser that emits continuous oscillation laser light, and the continuous oscillation laser light emitted by the continuous oscillation laser is on the downstream side of the moving direction of the beam spot relative to the aforementioned beam spot. The energy density of the part is set to be higher than the energy density of the part on the upstream side of the movement direction of the beam spot.

In the above aspect, it is preferable that the energy density of the upstream portion in the beam spot is set to gradually decrease toward the upstream side of the movement direction.

In terms of the above aspect, the aforementioned continuous oscillation laser-based semiconductor laser is preferable.

In the above aspect, it is preferable that the energy density in the downstream portion of the beam spot is set to be higher than the threshold for melting the amorphous silicon film, and the upstream side of the beam spot The energy density in the part is set toward the upstream side of the aforementioned moving direction, and gradually decreases by the aforementioned threshold value.

In the above aspect, it is preferable that the beam spot is formed in an elongated rectangular shape, and the long axis of the beam spot is arranged in a direction orthogonal to the moving direction.

In the above aspect, it is preferable that the laser beam irradiation unit is provided with: an asymmetric cylindrical lens, which is set to be compared with the energy density of the upstream part of the beam spot, and the downstream Part of the energy density is higher. (Effect of Invention)

With the present invention, it is possible to stably form a polycrystalline silicon film or a pseudo-single crystal silicon film with high mobility in a necessary area. The laser irradiation conditions of the substrate to be processed can be controlled well, and a substantial cost reduction can be achieved. The laser annealing method and laser annealing device.

Hereinafter, the laser annealing method and the laser annealing device of the embodiment of the present invention will be described in detail based on the drawings. However, it should be noted that if the figure is a model, the number of members, the size of each member, the ratio of the dimensions, the shape, etc. are different from the actual ones. In addition, the drawings also include portions where the relationship or ratio or shape of each other is different.

[Implementation form] Before describing the laser annealing method, an example of a substrate to be processed that is annealed by the laser annealing method and the laser annealing device 10 used in the laser annealing method will be described.

(Substrate to be processed) As shown in FIG. 1, the substrate 1 to be processed includes: a glass substrate 2, a gate wiring 3 arranged on the surface of the glass substrate 2, a gate insulating film 4 formed on the glass substrate 2 and the gate wiring 3, And an amorphous silicon film 5 deposited on the entire gate insulating film 4. The substrate 1 to be processed becomes a TFT substrate into which a thin film transistor (TFT) or the like is finally formed. Among them, in this embodiment, the entire area of the amorphous silicon film 5 is set as a region to be modified, but it is not limited to this, and the size or shape can be changed appropriately.

(Schematic structure of laser annealing equipment) Hereinafter, the schematic configuration of the laser annealing apparatus 10 of this embodiment will be described using FIGS. 1 to 4. As shown in FIG. 1, the laser annealing apparatus 10 includes a base 11 and a laser beam irradiation unit 12.

The base 11 is provided with a substrate conveying means (not shown). In the laser annealing apparatus 10, the substrate 1 to be processed is placed on the base 11, and the substrate conveying means (not shown) is used to move toward the relative movement direction Tr to the beam spot LBS described later. It is transported in the opposite direction of board movement T. Among them, as shown in FIG. 6-1, the relative movement direction Tr of the beam spot LBS refers to the direction indicated by the arrow Tr in FIG. 6-1, which is opposite to the substrate movement direction T of the substrate 1 to be processed.

As shown in FIG. 1, the laser beam irradiation unit 12 includes: a semiconductor laser 13 that oscillates continuous oscillation laser light (CW laser light) as a light source; a first lens 14; a second lens 15; and a first compound eye Lens 16; second fly-eye lens 17; first cylindrical lens 18; second cylindrical lens 19; and asymmetric cylindrical lens 20. In the laser beam irradiation section 12, as shown in FIG. 4, it is set so that the beam spot LBS projected on the amorphous silicon film 5 becomes an elongated rectangular shape.

In this embodiment, the continuous oscillation laser light system oscillated by the semiconductor laser 13 becomes a laser beam that is diffused and expanded by the first lens 14 and the second lens 15. The laser beam oscillated by the semiconductor laser 13 (the laser beam in position A in FIG. 1) has an energy density distribution as shown in FIG. 3(A), forming a symmetrical Gaussian distribution. In addition, the laser beam passing through the second cylindrical lens 19 forms a rectangular wave-like energy density distribution as shown in FIG. 3(B).

As shown in FIGS. 1 and 2, the asymmetric lenticular lens 20 is formed with a convex lens portion 21 and a concave lens portion 22 so as to extend along the longitudinal direction. As shown in FIG. 1, the convex lens portion 21 has a function of converging the light rays constituting the laser beam LB. In addition, the concave lens portion 22 has a function of dispersing the light constituting the laser beam LB.

Therefore, as shown in FIG. 3(C), the short axis direction of the laser beam LB (the laser beam at position C in FIG. 1) passing through the asymmetric cylindrical lens 20 (forms parallel to the substrate moving direction T) The distribution of energy density in the direction) has: a high area AH and a low area AL. If the high area AH is projected as part of the beam spot LBS, the temperature at which the amorphous silicon film 5 is heated due to the high energy density is set to be higher than the threshold value of the temperature at which the amorphous silicon film 5 is melted. high.

On the other hand, in the low energy density area AL shown in FIG. 3(C), the energy density is set to gradually decrease toward the upstream side of the movement direction of the beam spot LBS (the direction opposite to the substrate movement direction T) .

In the slope part SP in the energy density distribution of the low region AL in FIG. 3(C), the slope gradually decreases by the temperature at which the amorphous silicon film 5 is melted. The degree of inclination of the inclined portion SP is set based on experimental values.

(Laser annealing method) The laser annealing device 10 of the present embodiment has been described above, and then the laser annealing method in which the laser annealing device 10 is used to perform the laser annealing treatment on the amorphous silicon film 5 on the surface of the substrate 1 to be processed.

In this embodiment, an example in which a plurality of substrates 1 to be processed is arranged on the base 11 as shown in FIG. 4 is used for description, but it is not limited to the processing mode shown above. Hereinafter, the laser annealing process is performed on the entire surface of the amorphous silicon film 5 on the surface of the substrate 1 to be processed as shown in FIG. 5-1.

First, with respect to the position of the beam spot LBS formed by the laser beam irradiation unit 12, the substrate 1 to be processed is arranged at the standby position. However, at this point, the laser beam irradiation unit 12 is in an OFF state.

Next, while the position of the beam spot LBS is fixed, the substrate 1 to be processed is conveyed at a predetermined speed in the substrate movement direction T. As shown in FIG. 5-2, when the edge portion of the amorphous silicon film 5, which is a region to be modified, moves to the position of the projected beam spot LBS, the laser beam irradiation portion 12 is formed in a predetermined short time as After ON, switch to OFF.

In this embodiment, by irradiation of the laser beam at the beam point LBS for a short time, a seed region 5A is formed on the edge of the amorphous silicon film 5 (refer to FIGS. 5-3 and 6- 1). Among them, the width dimension W in the minor axis direction of the seed crystal region 5A shown in Fig. 6-1 is the same as the width in the minor axis direction of the beam spot LBS, as shown in Fig. 6-2, corresponding to the beam spot LBS The time width t in the energy density distribution in the short axis direction (substrate length direction) of.

Among them, when annealing by the beam spot LBS for a predetermined short time is performed, the amorphous silicon film 5 in the region corresponding to the high region AH shown in FIG. 3(C) is melted instantaneously. At this time, the amorphous silicon film 5 (melted silicon) after the melting of the amorphous silicon film 5 in the region corresponding to the low area AL gradually decreases toward the substrate moving direction T with a temperature gradient (gradient of energy density) toward the substrate The moving direction T forms a seed crystal region 5A made of microcrystalline silicon.

Next, immediately after the formation of the seed region 5A as described above, as shown in FIG. 6-2, the laser beam irradiating unit 12 is turned on again to restart the irradiation of the laser beam LB. At this time, the substrate 1 to be processed moves along the substrate movement direction T at a constant speed. Next, when reaching the position where the beam spot LBS is projected on the other end edge of the target substrate 1 to be modified, the laser beam irradiation unit 12 is turned OFF.

By performing the laser annealing method as shown above, as shown in Fig. 6-1, from one end edge to the other end edge of the amorphous silicon film 5, substantially the entire area of the intended modification area can be modified. It is a pseudo-single crystal silicon film 5B which is crystalline silicon. Here, when the pseudo-single-crystal silicon film 5B grows, the seed region 5A serves as a starting point to promote the crystal growth of the good-quality pseudo-single-crystal silicon film 5B. However, in the above embodiment, when forming the seed region 5A, the beam spot LBS having the distribution of the high area AH and the low area AL of energy intensity is used, but a beam spot having a uniform energy intensity may also be used. The formation of the seed region 5A as shown above can also be performed in a state where the substrate 1 to be processed is stationary relative to the beam spot LBS. In addition, the laser used to form the seed crystal region 5A may also be a pulse laser.

As described above, in the laser annealing method of this embodiment, CW laser light emitted from a continuous oscillation laser is used as the laser light. In addition, in this laser annealing method, the energy density of the downstream portion (high area AH) in the relative movement direction (the direction opposite to the substrate movement direction T) of the beam spot LBS is set to be higher than that of the upstream The energy density of the part (low area AL) is higher.

Next, in this embodiment, as shown in FIG. 6-2, after the seed region 5A is formed, the laser beam irradiation unit 12 is turned off to stop the emission of the continuous oscillation laser light. After that, the emission of continuously oscillating laser light is started within a predetermined short time, and the beam spot LBS is moved relative to the substrate 1 to be processed.

In this embodiment, as shown in the above-mentioned laser annealing method, the energy density of the low region AH (upstream part) in the beam spot LBS is set toward the moving direction (the direction opposite to the substrate moving direction T) Tr The upstream side of φ is gradually reduced, and only the beam spot LBS is projected toward the amorphous silicon film 5 to form a good seed crystal region 5A. Therefore, the seed region 5A can be used as a starting point, and it can be connected to the growth of the subsequent good pseudo-single crystal silicon film 5B.

The laser annealing device 10 of this embodiment uses a semiconductor laser as a continuous oscillation laser, so that the device can be miniaturized.

In the above-mentioned laser annealing method and laser annealing device 10, the beam spot LBS is formed into an elongated rectangular shape, and the long axis of the beam spot LBS is set to be opposite to the moving direction (the direction opposite to the substrate moving direction T). )Tr is perpendicular to the direction, so that it can also correspond to a wide modified region.

(Laser annealing method and effect of laser annealing device) With the laser annealing method and laser annealing device 10 of this embodiment, crystalline silicon such as a polycrystalline silicon film or a pseudo-single crystal silicon film with high mobility can be stably formed in a necessary area.

In addition, with the laser annealing device 10 of this embodiment, continuous oscillating laser light can be used, especially semiconductor laser 13 can be used, so the laser irradiation conditions of the substrate 1 to be processed can be controlled well, and a substantial cost can be achieved.化.

In the laser annealing apparatus 10 of the present embodiment, a single light source can be used for the production of the seed region 5A and the production of the pseudo-single crystal silicon film 5B, which has the effect of greatly reducing the number of laser annealing processes. Therefore, by applying the laser annealing apparatus 10 of this embodiment to the manufacture of TFTs, the TFT manufacturing process can be simplified.

[Other embodiments] The embodiments have been described above, but it should be understood that the statements and drawings constituting a part of the disclosure of the embodiments are not meant to limit the present invention. Those who are familiar with the technology in this field can clearly understand various alternative embodiments, embodiments, and application technologies from this disclosure.

For example, in the laser annealing method and the laser annealing device 10 of the above-mentioned embodiment, the semiconductor laser 13 which oscillates continuous oscillating laser light (CW laser light) as a light source is applied, but it is not limited to this. Various lasers that oscillate continuously oscillating laser light, such as solid lasers, gas lasers, and metal lasers, can also be used. In addition, for continuous oscillation lasers, the pulse width is longer than the cooling time of molten silicon. For example, pseudo-continuous oscillation lasers including lasers with pulse widths of hundreds of ns to 1 ms or more are also The scope of application of the present invention.

In the laser annealing method of the above-mentioned embodiment, as shown in Fig. 6-2, after the seed region 5A is formed, the laser beam irradiation section 12 is turned OFF to stop the emission of the continuous oscillation laser light. As shown in other embodiments of FIG. 6-3, after forming the seed crystal region 5A, the beam spot LBS is continuously moved relatively.

In the laser annealing device 10 of the above-mentioned embodiment, a structure having a concave lens portion 22 as the asymmetric lenticular lens 20 is applicable, but it is also applicable to a convex lens like the asymmetric lenticular lens 20A shown in FIG. 7 The constructor of the part 21 and the plane part 23. Among them, the concave lens portion 22 of the asymmetric lenticular lens 20 shown in FIG. 2 or the flat portion 23 of the asymmetric lenticular lens 20 shown in FIG. 7 should be selected, which can be made according to the The energy density distribution of the beam spot LBS is determined.

In the above-mentioned embodiment, the pseudo-single crystal silicon film 5B is formed as a crystalline silicon film, but of course, it may be formed in a structure in which a polycrystalline silicon film is grown from a seed region. At this time, the seed region 5A can be used as a starting point to form a good polysilicon film.

A, B, C: location AH: High area AL: low area LB: Laser beam LBS: beam point SP: Inclined part t: time width T: substrate movement direction (the direction opposite to the relative movement direction Tr of the beam spot) Tr: relative movement direction W: wide size 1: substrate to be processed 2: glass substrate 3: Gate wiring 4: Gate insulating film 5: Amorphous silicon film 5A: Seed crystal area 5B: pseudo-monocrystalline silicon (crystalline silicon) film 10: Laser annealing device 11: Abutment 12: Laser beam irradiation section 13: Semiconductor laser 14: The first lens 15: The second lens 16: 1st compound eye lens 17: 2nd compound eye lens 18: The first cylindrical lens 19: The second cylindrical lens 20: Asymmetric cylindrical lens 21: Convex lens part 22: Concave lens part

Fig. 1 is a schematic configuration diagram of a laser annealing device used in the laser annealing method of the embodiment of the present invention. [Fig. 2] A perspective view showing the asymmetric lenticular lens used in the laser annealing apparatus of the embodiment of the present invention. [Fig. 3(A)] is an explanatory diagram showing the energy density distribution of the laser beam at position A in Fig. 1, and [Fig. 3(B)] shows the energy of the laser beam at position B in Fig. 1 An explanatory diagram of the density distribution, [FIG. 3(C)] is an explanatory diagram showing the energy density distribution of the laser beam at position C in FIG. 1. Fig. 4 is a plan explanatory view showing a state in which the substrate to be processed is moved using the laser annealing apparatus of the embodiment of the present invention to start laser annealing. [FIG. 5-1] is a plan explanatory view showing a substrate to be processed that is subjected to laser annealing by the laser annealing method of the embodiment of the present invention. [Fig. 5-2] is a plan explanatory view showing the state of projecting a beam spot on the edge of a planned modification area by the laser annealing method of the embodiment of the present invention. [Fig. 5-3] is a plan explanatory view showing a state where the beam spot is moved to the middle part of the region to be modified by the laser annealing method of the embodiment of the present invention. [Fig. 6-1] is a plan explanatory view showing a state in which the beam spot is moved to the other edge of the intended modification area by the laser annealing method of the embodiment of the present invention. [FIG. 6-2] is an explanatory diagram showing the relationship between time and energy intensity when laser annealing is performed on a region to be modified by the laser annealing method of the embodiment of the present invention. [FIG. 6-3] It is an explanatory diagram showing the relationship between time and energy intensity when laser annealing is performed on a planned area to be modified by another example of the laser annealing method of the embodiment of the present invention. Fig. 7 is a perspective view showing a modification of the asymmetric lenticular lens used in the laser annealing apparatus of the present embodiment of the present invention.

A, B, C: location

LB: Laser beam

LBS: beam point

T: substrate movement direction (the direction opposite to the relative movement direction Tr of the beam spot)

1: substrate to be processed

2: glass substrate

3: Gate wiring

4: Gate insulating film

5: Amorphous silicon film

10: Laser annealing device

11: Abutment

12: Laser beam irradiation section

13: Semiconductor laser

14: The first lens

15: The second lens

16: 1st compound eye lens

17: 2nd compound eye lens

18: The first cylindrical lens

19: The second cylindrical lens

20: Asymmetric cylindrical lens

21: Convex lens part

22: Concave lens part

Claims (13)

A laser annealing method, which is a laser annealing method in which a predetermined area of the amorphous silicon film is modified to move the beam spot of the laser light relatively, and the foregoing amorphous silicon film is laser-annealed to be modified into crystalline silicon , The aforementioned laser light is a continuous oscillating laser light emitted from a continuous oscillating laser, The energy density of the downstream part of the beam spot in the moving direction in which the beam spot is relatively moved is set to be higher than the energy density of the upstream part of the beam spot in the moving direction, After projecting the beam spot on the end edge of the planned modification area to form a seed crystal area, The beam spot is moved toward the moving direction, and the entire area of the planned modification area is modified into a crystalline silicon film with the seed crystal region as a starting point. The laser annealing method of claim 1, wherein after forming the seed crystal region, the emission of the continuous oscillation laser light is stopped, After that, the emission of the continuous oscillation laser light is started within a predetermined time, and the beam spot is moved. A laser annealing method according to claim 1, wherein after the seed crystal region is formed, the beam spot is continuously moved while maintaining the state of emitting the continuously oscillating laser light. The laser annealing method according to any one of claims 1 to 3, wherein the energy density of the upstream portion in the beam spot gradually decreases toward the upstream side of the moving direction. The laser annealing method according to any one of claims 1 to 4, wherein the continuous oscillation laser is a semiconductor laser. The laser annealing method according to any one of claims 1 to 5, wherein the energy density of the downstream portion in the beam spot is set to be higher than the threshold value for melting the amorphous silicon film , The energy density in the upstream portion of the beam spot is set toward the upstream side of the movement direction, and gradually decreases by the threshold value. The laser annealing method according to any one of claims 1 to 6, wherein the beam spot is formed into an elongated rectangular shape, The beam spot is projected onto the amorphous silicon film so that the long axis of the beam spot becomes a direction orthogonal to the moving direction. A laser annealing device, which is a laser annealing device that moves the beam spot relative to an amorphous silicon film formed on a substrate to be processed, and performs laser annealing on the aforementioned amorphous silicon film to transform it into crystalline silicon , The department has: A base, which is configured with the aforementioned substrate to be processed; and The laser beam irradiation unit moves relative to the substrate to be processed arranged on the base, and is provided with a continuous oscillation laser that emits continuous oscillation laser light, The energy density of the downstream part of the beam spot of the continuous oscillation laser light emitted by the continuous oscillation laser in the moving direction in which the beam spot is relatively moved is set to be higher than the moving direction of the beam spot The energy density of the upstream part is higher. The laser annealing device according to claim 8, wherein the energy density of the upstream portion in the beam spot is set to gradually decrease toward the upstream side of the moving direction. The laser annealing device of claim 8 or 9, wherein the continuous oscillation laser is a semiconductor laser. The laser annealing device of any one of claims 8 to 10, wherein the energy density in the downstream portion of the beam spot is set to be higher than the threshold value for melting the amorphous silicon film, The energy density in the upstream portion of the beam spot is set toward the upstream side of the movement direction, and gradually decreases by the threshold value. The laser annealing device according to any one of claims 8 to 11, wherein the beam spot is formed in an elongated rectangular shape, The long axis of the beam spot is arranged in a direction orthogonal to the moving direction. The laser annealing device according to any one of claims 8 to 12, wherein the laser beam irradiating section includes: an asymmetric cylindrical lens, which is set to the upstream portion of the beam spot The energy density of the downstream part is higher.

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