JP2008300617A - Laser annealing method and laser annealing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a polycrystalline semiconductor film having a surface smoothed without fusing a substrate while suppressing manufacturing cost from rising. <P>SOLUTION: The semiconductor film 3 formed on the substrate 2 is irradiated with laser light 21 in a non-oxidative processing atmosphere containing hydrogen gas 31 and while a temperature of the substrate 2 is held not higher than a fusion point, the semiconductor film 3 is heated to not lower than 1,000°C to be fused, and then solidified to crystallize the semiconductor film 3. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a laser annealing method and a laser annealing apparatus for crystallizing a semiconductor film by irradiating the semiconductor film with laser light.

  Laser annealing is performed by irradiating laser light to an amorphous semiconductor film such as an amorphous silicon film formed on a substrate made of low-melting glass (usually non-alkali glass), and melting and solidifying it to recrystallize. This is a technique for forming a polycrystalline semiconductor film. Hereinafter, the amorphous silicon film is referred to as an a-Si film. Since the crystallized silicon film has better electrical characteristics than the a-Si film, a thin film transistor (: Thin Film Transistor: TFT) that drives a liquid crystal display that requires high-definition display such as a mobile phone or a digital still camera. ).

  FIG. 4 is a schematic cross-sectional view of a semiconductor film subjected to laser annealing. In FIG. 4, a polycrystalline semiconductor film 102 (such as polycrystalline silicon) is formed on a glass substrate 101. Since laser annealing is a process involving melting and solidification of the semiconductor film 102, protrusions (unevenness) called a ridge 103 are formed on the surface of the semiconductor film 102 due to a difference in volume density between melting and solidification. . According to the following Non-Patent Document 1, such a ridge 103 has a surface roughness Ra of about 10 nm. However, it deteriorates the step coverage of the insulating film formed thereon, and causes an interlayer short circuit and an interlayer current leakage. This contributes to a major problem that degrades the manufacturing yield and product reliability. In addition, research on forming an integrated circuit (microprocessor) for driving TFTs on the glass substrate 101 has been conducted, but it cannot be realized with the current roughness.

In view of such a problem, the following Patent Document 1 proposes a technique for removing a ridge formed by laser annealing. In this technique, a polycrystalline silicon film is irradiated with a gas cluster beam to remove ridges, and the surface of the silicon thin film is flattened.
However, according to this technique, a cluster beam device for removing the ridge is necessary, which increases the manufacturing cost of the transistor.

On the other hand, in the following Patent Document 2, Non-Patent Document 2, and Non-Patent Document 3, it is reported that migration of silicon atoms on the surface of a silicon substrate is promoted by heat treatment at 1000 ° C. or higher in a hydrogen atmosphere. Yes.
This method is effective when the substrate is made of a material that can withstand a temperature of 1000 ° C. or higher, such as silicon, but cannot be used for a substrate having a melting point of 600 ° C. or lower such as a glass substrate used for liquid crystal. .

Japanese Patent Laid-Open No. 2003-218028 JP 2002-542622 Gazette Proceedings of The 13th International Display, Workshops, Volume 2, Dec. 7,2006, pp. 869-873 “Analysis of Microscopic Deformation of Silicon Trench Structure”, Fuji Time Report, Vol. 75, no. 9 2002, pp497-500 “Structural Modification of a Trench by Hydrogen Annealing”, journal of the Korean Physical Society, Vol. 37, no. 6, December 2000, pp. 1034-1039

  The present invention has been made in view of the above problems, and a laser annealing method capable of forming a polycrystalline semiconductor film having a smooth surface without melting the substrate and suppressing an increase in manufacturing cost, and It is an object to provide a laser annealing apparatus.

In order to solve the above problems, the laser annealing method and laser annealing apparatus of the present invention employ the following means.
The laser annealing method of the present invention includes irradiating a semiconductor film containing hydrogen gas on a substrate in a non-oxidizing processing atmosphere with a laser beam, and maintaining the temperature of the substrate below the melting point. The semiconductor film is crystallized by heating the film to 1000 ° C. or higher and melting and then solidifying the film.

In the laser annealing method, the processing atmosphere includes a semiconductor etching gas for etching the semiconductor film.
In the laser annealing method, the semiconductor etching gas is a fluorine-based, chlorine-based or bromine-based gas.
In the laser annealing method, the processing atmosphere includes a low vapor pressure gas that makes an equilibrium vapor pressure at a melting point of the semiconductor film equal to or lower than an atmospheric pressure.

In the laser annealing method, the laser light is a fundamental wave or a harmonic of an excimer laser, a YAG laser, a YLF laser, a YVO ₄ laser, a glass laser, a semiconductor laser, or a CO ₂ laser.
In the laser annealing method, the laser light is pulsed light or continuous light.
In the laser annealing method, the hydrogen content in the processing atmosphere is 0 <H ₂ ≦ 100%.

  Further, the present invention provides a laser annealing apparatus for irradiating a semiconductor film formed on a substrate with laser light, and crystallizing the semiconductor film by melting and solidifying the semiconductor film, and at least a portion of the semiconductor film irradiated with the laser light. A gas supply device containing hydrogen gas and supplying a non-oxidizing processing atmosphere is provided in a covering range, the semiconductor film is irradiated with laser light in the processing atmosphere, and the temperature of the substrate is kept below the melting point The semiconductor film is crystallized by heating the semiconductor film to 1000 ° C. or higher and then melting and solidifying the semiconductor film.

In the laser annealing apparatus, the processing atmosphere includes a semiconductor etching gas for etching the semiconductor film.
In the laser annealing apparatus, the processing atmosphere includes a low vapor pressure gas that makes an equilibrium vapor pressure at a melting point of the semiconductor film equal to or lower than an atmospheric pressure.
Further, in the laser annealing apparatus, the gas supply device is a chamber that accommodates the substrate on which the semiconductor film is formed and fills the accommodation space of the substrate with the processing atmosphere.
In the laser annealing apparatus, the gas supply apparatus includes a fan that forcibly convects the processing atmosphere in the accommodation space.

  Further, in the laser annealing apparatus, the gas supply apparatus is a gas spraying apparatus that supplies the processing atmosphere only to a laser beam irradiation portion of the semiconductor film and a limited range around it.

  The laser annealing apparatus may further include a beam shaping optical system that shapes the laser light into a linear beam on the optical path of the laser light, the beam shaping optical system including: a long axis direction of the linear beam; And / or a homogenizer for homogenizing the energy distribution in the minor axis direction.

In the laser annealing apparatus, the homogenizer includes a cylindrical lens array or a waveguide that divides the laser light into a plurality of directions corresponding to a major axis direction and / or a minor axis direction of the linear beam, and the cylindrical lens. And a condenser lens that superimposes the laser beams divided by the lens array or the waveguide.
In the laser annealing apparatus, the homogenizer is an optical system including a diffractive optical element.

  According to the laser annealing method and the laser annealing apparatus of the present invention, the semiconductor film is heated to 1000 ° C. or more, whereby the surface energy is increased by the hydrogen gas contacting the semiconductor film, and the migration of semiconductor atoms is promoted. . In particular, the portion where the ridge is formed has a large surface area, so that the surface energy is larger than that of the other portions, so that the diffusion (movement) of the semiconductor atoms is promoted and the surface area is reduced. Therefore, formation of a ridge on the surface can be suppressed.

In addition, unlike the method of Patent Document 1 described above, a cluster beam device is not required, so that an increase in manufacturing cost can be suppressed.
Furthermore, while only the semiconductor film is heated and melted by laser light irradiation, the temperature of the substrate is kept below the melting point, so that the effect of migration by hydrogen can be obtained without melting the substrate.

  In addition, when laser annealing is performed in an atmosphere containing a semiconductor etching gas for etching a semiconductor film, the portion where the ridge is formed has a large surface area and a large surface energy, so that the reaction rate by the etching gas is higher than other portions. That is, since the etching rate is increased, the etching proceeds so as to be smoothed as a whole. Therefore, smoothing of the surface is further promoted by using the etching gas.

  Therefore, according to the present invention, it is possible to form a polycrystalline semiconductor film having a smooth surface without melting the substrate while suppressing an increase in manufacturing cost.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.

[First Embodiment]
FIG. 1 shows a schematic configuration of a laser annealing apparatus 10 according to the first embodiment of the present invention.
The laser annealing apparatus 10 is for crystallizing a semiconductor film 3 formed on a substrate 2 by irradiating a laser beam 1 and melting and solidifying the semiconductor film 3. As in the laser annealing apparatus of the present embodiment, in laser annealing, the laser beam 1 is usually shaped into a linear beam, and this linear beam is converted into a linear beam with respect to the substrate 2 (semiconductor film 3). The laser beam 1 is scanned with respect to the semiconductor film 3 on the substrate 2 by relatively moving in the minor axis direction.

In FIG. 1A, the direction parallel to the paper surface and perpendicular to the optical axis is the major axis direction of the linear beam, and in FIG. 1B, the direction parallel to the paper surface and perpendicular to the optical axis is the linear beam direction. The minor axis direction.
In FIG. 1A, an optical system that operates only in the minor axis direction is indicated by an imaginary line (broken line). In FIG. 1B, an optical system that operates only in the major axis direction is indicated by an imaginary line.

  The laser annealing apparatus 10 includes a laser light source 12 that oscillates laser light 1, a beam shaping optical system 13 that shapes the laser light 1 from the laser light source 12 and condenses it into a linear beam on the surface of the semiconductor film 3, And a substrate stage 4 on which the substrate 2 is placed.

In this embodiment, the substrate 2 is a glass substrate (for example, non-alkali glass), and an SiO ₂ film is formed on the glass substrate by a film forming method such as a plasma CVD method or a sputtering method, and an amorphous material is formed thereon. For example, an a-Si film is formed as the semiconductor film 3.

The type of the laser light source 12 is not particularly limited, and an excimer laser, a YAG laser, a YLF laser, a YVO ₄ laser, a glass laser, a semiconductor laser, a CO ₂ laser, or the like can be applied. In particular, solid lasers such as a YAG laser, a YLF laser, and a YVO ₄ laser have high reliability, and can stably use laser energy with high efficiency. Further, for the silicon film, due to the high absorption coefficient in the visible light region 330Nm～800nm, may be fundamental in the case of excimer lasers, the above YAG laser, YLF laser, YVO ₄ laser, when the glass laser The second or third harmonic may be used. Laser light 1 may be either pulsed light or continuous light.

  The beam shaping optical system 13 includes a beam expander 14 that expands the laser light 1 from the laser light source 12 in the major axis direction and the minor axis direction, and a long axis homogenizer 19 that equalizes the energy distribution in the major axis direction of the linear beam. And a short axis homogenizer 25 for uniformizing the energy distribution in the short axis direction of the linear beam.

  The beam expander 14 shown as one configuration example includes a convex spherical lens 15, a short-axis cylindrical lens 16 acting in the minor axis direction, and a long-axis cylindrical lens 17 acting in the major axis direction. In the beam expander 14 having this configuration, the enlargement ratio in the major axis direction and the minor axis direction can be set separately. The beam expander 14 may have another configuration, for example, a combination of a concave spherical lens and a convex spherical lens.

  As shown in FIG. 1A, a long-axis homogenizer 19 includes a long-axis cylindrical lens array 20 that divides incident laser light 1 into a plurality in the long-axis direction and a laser that is divided into a plurality in the long-axis direction. The long axis condenser lens 22 superimposes the light 1 in the long axis direction. A reflection mirror 23 is disposed in the optical path between the long-axis condenser lens 22 and the substrate 2 so that light emitted from the long-axis condenser lens 22 is reflected in the direction of the substrate 2. Yes.

  The short axis homogenizer 25 is a short axis cylindrical lens array 26 that divides an incident laser beam 1 into a plurality of short axis directions and a laser beam 1 that is divided into a plurality of short axis directions in a short axis direction. It includes an axial condenser lens 29 and a projection lens 30 that projects light emitted from the short axial condenser lens 29 onto the surface of the semiconductor film 3.

By the beam shaping optical system 13 configured as described above, the laser light 1 emitted from the laser light source is shaped into a linear beam and irradiated onto the semiconductor film 3.
The length in the major axis direction of the linear beam irradiated to the semiconductor film 3 can be, for example, several tens of mm, and the length in the minor axis direction can be, for example, several tens of μm.
In the laser beam 1, the energy distribution in the long axis direction of the linear beam is made uniform by the long axis homogenizer 19, and the energy distribution in the short axis direction of the linear beam is made uniform by the short axis homogenizer 25. The short axis cylindrical lens array 26 may be omitted, and only the energy distribution in the long axis direction may be made uniform.

The substrate 2 is held by the substrate stage 4 and conveyed in the short axis direction of the linear beam. By moving the substrate stage 4, the linear beam can be scanned relative to the semiconductor film 3 on the substrate 2 in the minor axis direction.
In contrast to the above, the laser beam 1 may be scanned by fixing the position of the substrate 2 and moving the irradiation position of the laser beam 1.

  The substrate stage 4 is heated to a predetermined temperature by a heating means (not shown). At this time, the substrate 2 is heated at a temperature not exceeding the melting point of the substrate 2. By doing so, laser annealing can be performed stably without melting the substrate 2. For example, when the substrate 2 is alkali-free glass, since the melting point is about 600 ° C., the substrate stage 5 is heated to a temperature not exceeding 600 ° C.

As shown in FIG. 1, the laser annealing apparatus 10 further includes a gas supply apparatus 40 that contains a hydrogen gas 31 and supplies a non-oxidizing treatment atmosphere in a range that covers at least a portion irradiated with the laser light 1 in the semiconductor film 3. Is provided.
In the present embodiment, the gas supply device 40 is a chamber 40A that accommodates the substrate 2 on which the semiconductor film 3 is formed and fills the accommodation space of the substrate 2 with the processing atmosphere. Therefore, the hydrogen gas 31 is introduced into the chamber 40A by a hydrogen gas introduction means (not shown).
The chamber 40A is provided with a transmission window 41 for transmitting the laser beam 1. Further, an exhaust pump 43 for exhausting the internal gas is connected to the chamber 40A.

The hydrogen content in the above processing atmosphere can be in the range of 0 <H ₂ ≦ 100%. However, when the hydrogen content is set to the explosion limit (5%) or more, the chamber 40A needs to have a highly airtight structure so as to almost completely block the entry of air from the outside. Therefore, in order to make it less than the explosion limit (5%), it is preferable to introduce an inert gas 32 (nitrogen gas, argon gas, helium gas, neon gas, etc.) into the chamber 40A as shown in FIG. This inert gas 32 also has a role of preventing oxidation of the surface of the semiconductor film 3 during annealing.
Here, the above-described “non-oxidizing treatment atmosphere containing hydrogen gas” is a concept including not only an atmosphere in which hydrogen is diluted with an inert gas 32 but also an atmosphere having a hydrogen content of 100%.

  The laser annealing method of the present invention can be implemented using the laser annealing apparatus 10 configured as described above. That is, in the laser annealing method of the present invention, the semiconductor film 3 is irradiated with the laser beam 1 in the above-described processing atmosphere, and the semiconductor film 3 is heated to 1000 ° C. or higher while the temperature of the substrate 2 is kept below the melting point. And then solidifying to crystallize the semiconductor film 3.

  Thus, by heating the semiconductor film 3 to 1000 ° C. or higher, the surface energy increasing action by the hydrogen gas 31 in contact with the semiconductor film 3 is exhibited, and the migration of semiconductor atoms is promoted. In particular, the portion where the ridge is formed has a large surface area, so that the surface energy is larger than that of the other portions, so that the diffusion (movement) of the semiconductor atoms is promoted and the surface area is reduced. Therefore, formation of a ridge on the surface can be suppressed.

In addition, unlike the method of Patent Document 1 described above, a cluster beam device is not required, so that an increase in manufacturing cost can be suppressed.
Further, only the semiconductor film 3 is heated and melted by the irradiation of the laser beam 1, while the temperature of the substrate 2 is kept below the melting point, so that the effect of migration by hydrogen can be obtained without melting the substrate 2. it can.

The processing atmosphere preferably includes a semiconductor etching gas 33 for etching the semiconductor film 3 as shown in FIG. The semiconductor etching gas 33 is introduced into the chamber 40A by etching gas introduction means (not shown). The semiconductor etching gas 33 can be fluorine, chlorine or bromine.
When laser annealing is performed in an atmosphere containing the semiconductor etching gas 33, the portion where the ridge is formed has a large surface area and a large surface energy. Therefore, the reaction rate by the etching gas is higher than other portions, that is, the etching rate is high. Therefore, the etching proceeds so as to be smoothed as a whole. Therefore, smoothing of the surface is further promoted by using the semiconductor etching gas 33.

  The semiconductor film 3 may be made of a compound semiconductor such as GaN (gallium nitride). For example, the melting point of GaN under atmospheric pressure is about 2220 ° C. or higher, and is normally used as an inert gas 32. Since the equilibrium vapor pressure in the generated nitrogen gas reaches about 6 GPa (about 60,000 atmospheres) or more, GaN is decomposed into Ga metal and nitrogen gas in a molten state under a low-pressure nitrogen atmosphere. In contrast, since the equilibrium vapor pressure of GaN in an ammonia atmosphere is 1 atm or less, GaN does not decompose even when heated to a temperature that melts under atmospheric pressure.

Therefore, when the semiconductor film 3 is a compound semiconductor having a high equilibrium vapor pressure at the melting point in the inert gas 32 atmosphere, as shown in FIG. A vapor pressure gas 34 is preferably included. The low vapor pressure gas 34 is introduced into the chamber 40A by low vapor pressure gas introduction means (not shown).
As described above, by adding the low vapor pressure gas 34 to the processing atmosphere, the semiconductor film 3 can be melted without being decomposed. As the low vapor pressure gas 34, ammonia or hydrazine can be used when the compound semiconductor is GaN, AsH ₃ can be used when the compound semiconductor is GaAs (gallium arsenide), and PH ₃ can be used when the compound semiconductor is InP (indium phosphide).

  When the hydrogen gas 31 is diluted with the inert gas 32, the hydrogen gas 31 is lighter than the inert gas 32, so that it may stay in the upper part of the chamber 40 </ b> A and hydrogen cannot be supplied well to the surface of the semiconductor film 3. Therefore, as shown in FIG. 1, it is preferable to provide a fan 35 for forcibly convection of the processing atmosphere inside the chamber 40A. With this configuration, the hydrogen gas 31 can be effectively supplied to the surface of the semiconductor film 3.

  Further, the gas supply device 40 may be a gas spraying device 40B shown in FIG. This gas spraying device 40B supplies a processing atmosphere 47 only to a portion of the semiconductor film 3 irradiated with the laser beam 1 and a limited range around it, and has a lower surface 44 that is close to and faces the substrate 2 in parallel. A flow path of the processing atmosphere 47 is formed between the lower surface 44 and the substrate 2 and the parallel opposing body 46 having the transmission window 45 through which the laser beam 1 is transmitted, and the flow rate is made uniform in the major axis direction of the linear beam. Gas injection means 48 for injecting the processing atmosphere 47 toward the surface of the substrate 2 at a position spaced apart from the irradiated portion of the laser beam 1 in the beam minor axis direction. The processing atmosphere 47 includes (1) 100% hydrogen gas, (2) a gas obtained by diluting the hydrogen gas 31 with the inert gas 32, and (3) a semiconductor etching gas 33 obtained by diluting the hydrogen gas 31 with the inert gas 32. Or (4) a gas obtained by further adding the low vapor pressure gas 34 to the gases (1) to (3).

  Since the gas spraying device 40B can supply the atmospheric gas to the irradiated portion of the laser beam 1, there is no need to provide the chamber 40A as shown in FIG. Since no time is required, the operating rate of the apparatus can be improved. Further, the processing atmosphere 47 can be efficiently and reliably supplied to the irradiated portion of the laser light 1 on the semiconductor film 3.

  The gas spraying device 40B is not limited to the configuration shown in FIG. 2, but has other configurations as long as it has a function of supplying an inert gas only to the irradiated portion of the laser beam 1 and a limited range around it. There may be. For example, the configuration shown in FIG. 2 or 4 of Japanese Patent No. 3502981 may be used.

[Second Embodiment]
FIG. 3 shows a schematic configuration of a laser annealing apparatus 10 according to the second embodiment of the present invention.
In the second embodiment, the long-axis homogenizer 19 includes a long-axis waveguide 38 that divides the incident laser beam 1 into a plurality of pieces in the long-axis direction, and a long laser beam 1 that is divided into a plurality of pieces in the long-axis direction. The long-axis condenser lens 22 is superposed in the axial direction. A waveguide introduction lens 37 that guides the laser beam 1 to the long-axis waveguide 38 is disposed on the entrance side of the long-axis waveguide 38. The energy distribution in the major axis direction of the linear beam can also be made uniform by the major axis homogenizer 19 of the present embodiment. Note that the short-axis homogenizer 25 may also be configured to make the energy distribution in the short-axis direction uniform by using a waveguide. The configuration of other parts of the present embodiment is the same as that of the first embodiment.

Also in this embodiment, the semiconductor film 3 is irradiated with the laser light 1 in a non-oxidizing treatment atmosphere containing the hydrogen gas 31 and the temperature of the substrate 2 is kept below the melting point, and the semiconductor film 3 is kept at 1000 ° C. or higher. A laser annealing method for crystallizing the semiconductor film 3 can be performed by heating and melting and then solidifying.
Accordingly, it is possible to form a polycrystalline semiconductor film having a smooth surface without melting the substrate 2 while suppressing an increase in manufacturing cost.

  The long-axis homogenizer 19 and the short-axis homogenizer 25 are not limited to those described in the first embodiment and the second embodiment described above, and are other means for equalizing the energy distribution using a known optical system. There may be. For example, the long axis homogenizer 19 / and / or the short axis homogenizer 25 may be an optical system including a diffractive optical element. Although a detailed description of the diffractive optical element is omitted, it is disclosed in, for example, Japanese Patent Application Laid-Open No. 2005-217209. In a diffractive optical element, a fine step is formed on a substrate such as quartz by a photoetching process or the like, and a diffraction pattern formed by laser light transmitted through each step portion has a desired energy distribution on the imaging surface (substrate surface). Prepare as obtained.

  Although the embodiments of the present invention have been described above, the embodiments of the present invention disclosed above are merely examples, and the scope of the present invention is not limited to these embodiments. . The scope of the present invention is indicated by the description of the scope of claims, and further includes meanings equivalent to the description of the scope of claims and all modifications within the scope.

1 is a diagram showing a schematic configuration of a laser annealing apparatus according to a first embodiment of the present invention. It is a figure which shows another structural example of a gas supply apparatus. It is a figure which shows schematic structure of the laser annealing apparatus concerning 2nd Embodiment of this invention. It is a figure explaining the ridge formed in the surface of a semiconductor film.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser beam 2 Substrate 3 Semiconductor film 4 Substrate stage 10 Laser annealing device 12 Laser light source 13 Beam shaping optical system 14 Beam expander 15 Convex spherical lens 16 Short axis cylindrical lens 17 Long axis cylindrical lens 19 Long axis homogenizer 20 Long Axis cylindrical lens array 22 Long axis condenser lens 25 Short axis homogenizer 26 Short axis cylindrical lens array 29 Short axis condenser lens 30 Projection lens 31 Hydrogen gas 32 Inert gas 33 Semiconductor etching gas 34 Low vapor pressure gas 35 Fan 40 Gas supply device 40A Chamber 40B Gas spraying device 41 Permeation window 43 Exhaust pump 44 Lower surface 45 Permeation window 46 Parallel opposing body 47 Processing atmosphere 48 Gas injection means

Claims (16)

  A semiconductor film containing hydrogen gas and exposed to a laser beam in a non-oxidizing processing atmosphere is irradiated with laser light, and the semiconductor film is heated to 1000 ° C. or higher while the temperature of the substrate is kept below the melting point. A laser annealing method, wherein the semiconductor film is crystallized by being melted and then solidified.   The laser annealing method according to claim 1, wherein the processing atmosphere includes a semiconductor etching gas for etching the semiconductor film.   The laser annealing method according to claim 2, wherein the semiconductor etching gas is a fluorine-based, chlorine-based or bromine-based gas.   The laser annealing method according to claim 1, wherein the processing atmosphere includes a low vapor pressure gas that makes an equilibrium vapor pressure at a melting point of the semiconductor film equal to or lower than an atmospheric pressure. The laser annealing method according to claim 1, wherein the laser light is a fundamental wave or a harmonic of an excimer laser, a YAG laser, a YLF laser, a YVO ₄ laser, a glass laser, a semiconductor laser, or a CO ₂ laser.   The laser annealing method according to claim 1, wherein the laser light is pulsed light or continuous light. The laser annealing method according to claim 1, wherein a hydrogen content in the processing atmosphere is 0 <H ₂ ≦ 100%. In a laser annealing apparatus for crystallization by irradiating a semiconductor film formed on a substrate with laser light and melting and solidifying the semiconductor film,
A gas supply device that includes a hydrogen gas and supplies a non-oxidizing treatment atmosphere in a range that covers at least a portion irradiated with laser light in the semiconductor film,
The semiconductor film is irradiated with laser light in the processing atmosphere, and the semiconductor film is heated to 1000 ° C. or more and melted and then solidified while maintaining the temperature of the substrate below the melting point. A laser annealing apparatus characterized by crystallizing.   The laser annealing apparatus according to claim 8, wherein the processing atmosphere includes a semiconductor etching gas for etching the semiconductor film.   The laser annealing apparatus according to claim 8, wherein the processing atmosphere includes a low vapor pressure gas that reduces an equilibrium vapor pressure at a melting point of the semiconductor film to an atmospheric pressure or lower.   The laser annealing apparatus according to claim 8, wherein the gas supply device is a chamber that houses a substrate on which the semiconductor film is formed and fills a housing space of the substrate with the processing atmosphere.   The laser annealing apparatus according to claim 11, wherein the gas supply device has a fan for forcibly convection of a processing atmosphere in the accommodation space.   The laser annealing apparatus according to claim 8, wherein the gas supply apparatus is a gas spraying apparatus that supplies the processing atmosphere only to a limited area around the irradiated portion of the semiconductor film and a surrounding area thereof.   A beam shaping optical system for shaping the laser light into a linear beam is provided on the optical path of the laser light, and the beam shaping optical system has an energy distribution in a major axis direction and / or a minor axis direction of the linear beam. The laser annealing apparatus according to claim 8, comprising a homogenizer for homogenization.   The homogenizer is divided by a cylindrical lens array or waveguide that divides the laser light into a plurality of directions corresponding to the major axis direction and / or minor axis direction of the linear beam, and the cylindrical lens array or waveguide. The laser annealing apparatus according to claim 14, further comprising a condenser lens that superimposes the laser beams.   The laser annealing apparatus according to claim 14, wherein the homogenizer is an optical system including a diffractive optical element.

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