JP2002139697A - Laser optical system using plural laser beams, and laser annealing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical system for controlling a laser beam irradiation profile for forming a thin film having superior crystallinity necessary for manufacturing of a high-performance thin-film transistor, in a laser heat treatment method. SOLUTION: The optical system for forming a liner beam shape on an amorphous or polycrystalline silicon film by forming the sectional intensity distribution of laser beams radiated from laser oscillators is so constituted, that the plural laser beams radiated from the plural laser oscillators are made uniform in the intensity distribution of a major axis direction by a beam intensity distribution forming means, and the top of the amorphous or polycrystalline silicon film formed on a substrate is irradiated with the linear beam shape. Irradiated area can be increased and productivity improved, in a state of maintaining the necessary irradiation intensity. The apparatus constitution is simplified, and the number of optical parts reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser heat treatment apparatus for forming a polycrystalline semiconductor film having excellent crystallinity in order to realize a high mobility thin film transistor, and an optical system thereof.

[0002]

2. Description of the Related Art A pixel portion of a liquid crystal panel uses a polycrystalline silicon film formed on a glass or quartz substrate to form an image by switching thin film transistors formed on the polycrystalline silicon film. I have. Such a polycrystalline silicon film is usually formed by first forming an amorphous silicon film on a substrate, heating the polycrystalline silicon film to form a polycrystalline silicon film, and using the polycrystalline silicon film as a substrate. A pixel transistor circuit is formed.

However, since the crystallinity of the silicon film constituting the active layer of the transistor is poor, the performance of the thin film transistor is low, as represented by the mobility, and the production of an integrated circuit that requires high speed and high functionality is required. It was difficult. Therefore, in order to realize a high mobility thin film transistor,
As a method for improving the crystallinity of a silicon film, a laser heat treatment for increasing the crystallinity by irradiating a laser to a silicon film formed on a substrate has been performed.

The following relationship exists between the crystallinity of a silicon film and the mobility of a thin film transistor. The silicon film obtained by the laser heat treatment is generally polycrystalline, but the crystal grain boundaries of the polycrystal are constituted by lattice defects, and these defects scatter carriers in the thin film transistor active layer and hinder movement. Therefore, in order to increase the mobility of the thin film transistor, it is important to reduce the frequency of crossing the crystal grain boundary while moving the active layer of the carrier, and thus it is necessary to reduce the lattice defect density. The purpose of laser heat treatment is to form a polycrystalline silicon film having a large crystal grain size and having few lattice defects at crystal grain boundaries.

As a conventional laser heat treatment, for example, a technique is known in which an excimer laser having a short wavelength is used to irradiate and heat a semiconductor film in a rectangular distribution with a laser beam. For example, Japanese Patent Application Laid-Open Nos.
No. 33077 discloses that a laser beam from an oscillator is
The laser beam passes through cylinder arrays that cross each other in a plane perpendicular to the optical axis, passes through a converging lens in front of the cylinder array, and converges on the surface of the semiconductor film. According to this method, a laser beam having a Gaussian distribution is made to have a uniform intensity distribution in two orthogonal directions by two cylinder arrays, and an irradiation laser beam on a semiconductor film surface is orthogonal on the semiconductor surface. The width is different in two directions, and the irradiation laser beam is swept in one of the two directions to form a polycrystalline band having a constant width on the semiconductor film.

[0006]

When performing heat treatment by sweeping using a rectangular irradiation laser beam in heat treatment using a laser as a light source, the profile in the sweep direction greatly affects the recrystallization growth process and is orthogonal to the profile. Since the distribution of the direction affects the region where the crystal grows, an appropriate profile and irradiation intensity must be selected in order to manufacture a thin film transistor having excellent characteristics. However, the conventional optical system for forming a rectangular beam cannot have a sufficiently narrow width.

Further, in the conventional liquid crystal panel, a driver circuit for driving these pixel transistors is independently provided outside. However, it is expected that the driver circuits are simultaneously formed close to the pixel transistors. If possible by increasing the crystallinity, there will be significant advantages in terms of the manufacturing cost and reliability of the liquid crystal panel.

The inventor has proposed an optical system for forming a linear irradiation laser beam in Japanese Patent Application No. 11-179233. FIG. 5 shows a schematic diagram of this optical system. The laser beam 2 emitted from the laser oscillator 1 is
The light passes through the intensity distribution shaping means 30 and the beam shape shaping means 40 and is irradiated onto the silicon film 5 on the substrate 50.

In this optical system, a laser beam 2 emitted from a laser oscillator 1 has an incident surface A of an intensity distribution shaping means 30, for example, as shown in FIG. The intensity distribution XA in the x direction in the A plane and the intensity distribution YA in the y direction in the A plane are substantially Gaussian. The intensity distribution shaping means 30 includes, for example,
The intensity distribution in the x direction is stored as a Gaussian distribution, and only the intensity distribution in the y direction is smoothed. For this reason, the beam shape PB of the laser beam on the exit surface B of the intensity distribution shaping means 30 is converted into a substantially rectangular shape, and the intensity distribution XB in the x direction on the B surface is obtained.
The intensity distribution XA in the x direction on the surface A is maintained, and the intensity distribution YB in the y direction on the surface B is shaped almost like a top hat distribution. This laser beam is applied to
The magnification in the x direction and the y direction is adjusted by 0, and the silicon film 5 is irradiated with a rectangular beam shape and heated. However, with such a single laser beam, the laser output is limited due to the capability of the oscillator, and it is necessary to reduce the length of the irradiation light in the longitudinal direction in order to obtain a necessary irradiation intensity. Had the drawback of being low.

The present invention has been made to solve such a problem. Generally, a semiconductor film formed on a substrate has a high crystallization speed by laser heat treatment and has a small number of lattice defects in the polycrystal. An object of the present invention is to provide a laser optical system for producing a crystalline semiconductor film, particularly a silicon film, and a highly productive laser annealing apparatus using the same.

[0011]

A laser optical system according to the present invention comprises an intensity distribution shaping means for irradiating a laser beam emitted from a laser oscillator onto a surface of an amorphous or polycrystalline semiconductor film formed on a substrate. Although the laser optical system for laser annealing including, the intensity distribution shaping means,
A plurality of laser beams from a plurality of laser oscillators are incident, and the intensity distribution of each irradiation laser beam applied to the semiconductor film surface is made uniform in one direction in a cross section perpendicular to the optical axis of the laser beam, and the cross section is made uniform. The width of the semiconductor film is sharply narrowed in the direction orthogonal to the one direction, and the semiconductor film is melted and polycrystallized by the irradiation laser beam.

As the intensity distribution shaping means, a single waveguide having a pair of opposed reflecting surfaces that alternately reflect a plurality of laser beams incident from a plurality of laser oscillators in the one direction can be used. . The waveguide makes the intensity distribution in the longitudinal direction of the irradiation beam uniform, and the irradiation laser beam on the semiconductor film becomes a combined light of a plurality of laser beams, so that the intensity distribution can be increased. Speed can be increased.

Further, a plurality of waveguides having a pair of opposed reflecting surfaces which reflect in the above-mentioned one direction corresponding to each laser beam from the plurality of laser oscillators can be used as the intensity distribution shaping means. It is preferable that the irradiation laser beam formed on the semiconductor film by such a plurality of waveguides be arranged substantially linearly in the one direction, that is, in the longitudinal direction of the irradiation laser beam. Using such a plurality of waveguides, each laser beam is arranged in a narrow linear irradiation laser beam, so that it is possible to extend in the longitudinal direction without reducing the irradiation intensity of each irradiation laser beam. When a plurality of irradiation laser beams are integrated and swept in the orthogonal direction, the irradiation area of one scanning pass can be widened.

[0014] The optical system may further include a beam shape shaping means for converging the radiation beam from the intensity distribution shaping means in the orthogonal direction, and the beam shape shaping means may be a cylindrical lens. The cylindrical lens irradiates a beam from the intensity distribution shaping means so as to form a laser beam into a linear beam having a narrow width in the orthogonal direction, whereby a linear irradiating laser beam is formed on the semiconductor film. Is obtained.

Further, the irradiation laser beams formed on the semiconductor film from the plurality of waveguides are arranged in the above-mentioned one direction, but not in a straight line but alternately. It may be arranged so that it does not become. Also in this case, if a plurality of irradiation laser beams having such an arrangement are swept in the orthogonal direction, the irradiation area of one scanning pass can be similarly widened.

The laser optical system of the present invention can be applied to a silicon film as a semiconductor film, and in particular, can be used as a silicon substrate for a thin film transistor in a pixel portion of a liquid crystal display. 320 to 8 for the laser beam
A pulsed laser having an oscillation wavelength in the range of 00 nm can be used. Since the laser light in this wavelength region has an appropriate transmittance particularly to the silicon film, uniform heating in the film thickness direction can be obtained. A harmonic of a solid-state oscillation laser can be used for such a laser beam.

A laser annealing apparatus according to the present invention includes a laser oscillator that emits a laser beam to the laser optical system using the above laser optical system, a stage for mounting and fixing a substrate, and the above optical system or stage. And a scanning mechanism for scanning the irradiation laser beam on the semiconductor film in the orthogonal direction.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the laser optical system according to the present invention combines a plurality of laser beams from a plurality of laser light sources with a single series of intensity distribution shaping means and beam shape shaping means to synthesize incident light. Then, the surface of the semiconductor film is irradiated, and the irradiated laser beam is extended in one direction to form a uniform intensity distribution, and is adjusted to a linear shape having a narrow width in the other orthogonal direction.

In the present invention, the single-series intensity distribution shaping means and the beam shape shaping means are each provided with a pair of reflection faces facing in one direction (hereinafter referred to as y-direction) in a plane perpendicular to the beam optical axis. A plurality of laser beams from a plurality of laser oscillators using a waveguide having a surface and a cylindrical lens, for example, a cylindrical lens converging in an orthogonal direction (hereinafter, referred to as an x direction) orthogonal to the one direction, The semiconductor laser is irradiated with a high-energy irradiation beam, which is synthesized by a single series of intensity distribution shaping means.

In another embodiment, a single-series intensity distribution shaping unit and a beam shape shaping unit are each provided with a plurality of waveguides having a pair of reflecting surfaces opposed to each other in the y direction corresponding to a plurality of laser beams. Using a single cylindrical lens that converges radiation beams from these waveguides in the x-direction, for example, a cylindrical lens, a plurality of laser beams from a plurality of laser oscillators are irradiated on the semiconductor film surface as irradiation laser beams, respectively. Is what you do.

Here, the object of the laser irradiation of the present invention is a semiconductor film having a relatively large area, and the semiconductor film is coated on an appropriate substrate by, for example, a vapor phase method such as a vapor deposition method. An amorphous thin film formed by deposition is used, or this amorphous coating is preliminarily annealed to
A partially or completely crystallized semiconductor film can be used.

Examples of the semiconductor film include a silicon film. The silicon film is used as a semiconductor substrate in a thin film transistor element constituting a pixel portion of the liquid crystal panel.
An amorphous silicon film formed on a substrate is used, and polycrystallized by irradiation with a laser beam.

As an example of an amorphous silicon film, a silicon oxide film having a thickness of, for example, about 200 nm is formed as a base film 51 on a ceramics or glass substrate 50 by CVD (Chemical V).
aporDeposition) method, and a thickness of 50
nm amorphous silicon film, etc., by low pressure CVD (Low Pressu
re Chemical Vapor Deposition). The amorphous silicon film thus formed may be partially or entirely polycrystalline by preliminary annealing.

Taking a silicon film as an example, the surface of the amorphous or crystalline silicon film is irradiated with laser light by the above-mentioned optical system so that the irradiation laser beam becomes linear. The laser beam is scanned in the width direction (in the x direction). The silicon film is heated at the irradiation site by absorbing the linearly irradiated laser light and locally melted in a linear or rectangular shape along the linear shape of the irradiated laser beam. At this time, a temperature gradient does not occur in the longitudinal direction of the irradiation laser beam, that is, the y direction because the intensity distribution of the laser beam 2 is uniform, and a temperature gradient occurs only in the x direction. Then, when the melted portion is cooled with the movement of the irradiation laser beam, the crystal grows in accordance with the temperature gradient, so that the one-dimensional growth (unidirectional growth) in the moving direction of the substrate 50, that is, the x direction, Large crystal grains having a crystal grain size of about several μm are formed, and the large crystal grains have a relatively low lattice defect density. In this embodiment, a plurality of laser oscillators, for example, laser beams from three laser oscillators are combined by a single intensity distribution shaping means as in the following example. Has a high energy density, so that the scanning speed for melting the silicon film can be increased, and the crystallization area per unit time can be increased.

According to the laser oscillator of the present invention, an amorphous or polycrystalline silicon film is crystallized from 320 nm to 8 nm.
Lasers having an oscillation wavelength between 00 nm are more effective. In other words, light having an oscillation wavelength between 320 nm and 800 nm has a relatively small absorption coefficient with respect to amorphous silicon, and the laser light penetrates well in the film thickness direction, so that the silicon film is heated almost uniformly in the film thickness direction. Therefore, the lateral temperature distribution in the silicon film generated by the laser irradiation is:
It is formed only in the x direction. Therefore, the beam portion having a certain intensity or more of the amorphous or polycrystalline silicon film as the film material on the substrate is melted in the entire depth direction.

An optical system using a laser in the above-mentioned wavelength range can uniformly heat the thickness direction of an amorphous or polycrystalline silicon film, and can be used for manufacturing a high-performance thin film transistor by a laser heat treatment method. The required thin film with excellent crystallinity can be obtained

As a laser having an oscillation wavelength between 340 nm and 800 nm, for example, a solid-state laser harmonic generation source is preferable. That is, the second harmonic (532 nm) and the third harmonic (355 nm) of the Nd: YAG laser, Nd: Y
The second harmonic (524 nm) or the third harmonic (349 nm) of the LF laser, or the second harmonic (515 nm) or the third harmonic (344 nm) of the Yb: YAG laser is used. Alternatively, a fundamental wave or second harmonic of Ti: sapphire may be used. By using the solid-state laser harmonic generation source, laser light having an oscillation wavelength between 340 nm and 800 nm can be efficiently obtained with a compact device, and stable operation can be performed for a long time. Since the silicon film can be uniformly heated and melted in the thickness direction, a thin film having excellent crystallinity required for manufacturing a high-performance thin film transistor by a laser heat treatment method can be obtained.

Embodiment 1 The laser optical system of this embodiment has a plurality of laser oscillators 1a to 1c in FIG.
The laser beams 2a to 2c emitted from the laser beam enter the intensity distribution shaping unit 30. The intensity distribution shaping unit uniforms the intensity distribution of the laser beam in the y direction in a section perpendicular to the optical axis of the laser beam. The beam diverges in the x direction orthogonal to the y direction and enters the beam shape shaping unit 40. The beam shape shaping means 40 diverges substantially in the y-direction, forms a uniform intensity distribution with a constant length on the surface of the semiconductor film 5, and converges in the x-direction to form an irradiation laser beam. The intensity distribution in the x direction is made to have a sharp narrow width. Such a linear irradiation laser beam is applied to an amorphous or polycrystalline semiconductor film.

More specifically, the optical system of this example is shown in FIG.
In (A, B), for the three laser oscillators 1a to 1c, a single condenser lens 32 and an intensity distribution shaping unit 3 are provided.
0 followed by a single waveguide 33 and this waveguide 3
The beam shape shaping means 40 following 3 comprises a cylindrical lens, that is, a cylindrical lens.

The waveguide 33 has a pair of reflecting surfaces facing in the y-direction (the reflecting surfaces are parallel or tapered in the x-direction), and light is transmitted in the y-direction. It can reflect alternately and can transmit light between the reflecting surfaces. The waveguide is a transparent block having such opposing reflective surfaces, for example,
Optical glass blocks are available. The waveguide has a space between a pair of reflecting surfaces facing each other in the y direction.
Includes twin mirrors. The example shown in FIG. 1 shows that the waveguide 33 is a pair of reflecting mirrors facing each other in the y direction and separated from each other.

As shown in FIGS. 1A and 1B, the condenser lens 32 collects the laser beams 2a to 2c emitted from the plurality of laser oscillators 1a to 1c by a single condenser lens 32. A part of each of the condensed laser beams 2a to 2c is arranged so as to be illuminated and incident between a pair of reflecting mirrors, and travels while reflecting between the reflecting surfaces in the y direction toward the optical axis. , In the x-direction, the radiation proceeds from the focal position, and is radiated from the irradiation side of the waveguide 33, and the laser beams 2a to
2c is synthesized.

The light radiated from the waveguide 33 is incident on the beam shape shaping means 40, but the beam shape shaping means 4
At 0, only the x direction of the incident light is converged by the beam shape shaping means 40 using a cylindrical lens, and condensed linearly into a semiconductor film on the substrate. Since the incident light travels substantially straight in the y direction, the length of the semiconductor film on the substrate becomes longer, and the intensity distribution in the y direction becomes uniform.

In this example, three parallel laser beams 2
a, 2b and 2c, the laser beams 2a and 2c on both sides are reflected by one set of reflecting mirrors M1 and M2 and the other set of reflecting mirrors M3 and M4, respectively, so that the laser beams 2a to 2c are reflected. The interval 2c is narrowed, and the reflecting mirror M allows three parallel beams to be supplied through the single condensing lens 32 between the reflecting surfaces of the waveguide 33. As shown in this example, a plurality of laser beams are combined into a single waveguide 33.
Into the laser oscillators 1a to 1a.
c can be arranged at appropriate intervals, and the laser beams 2a to 2c can be arranged at appropriate intervals.

As a modification of this embodiment, a transparent block having reflecting surfaces on both opposing surfaces can be used as the waveguide of the intensity distribution shaping means, and the hollow reflecting mirrors 34a and 34a shown in FIG. 1 can be used. The waveguide of 34b is replaced with a transparent block having a reflecting surface facing the same.

Embodiment 2 In this embodiment, as shown in FIG. 2, one laser oscillator 1a to 1c is used.
The strength distribution shaping means 3 is provided.
Laser beam from a single beam shaper 40
Is used to form a single linear irradiation laser beam on the semiconductor film surface 5.
Has a plurality of condensing lenses 32 corresponding to a plurality of laser oscillators 1a to 1c and a plurality of waveguides 33a to 33b as intensity distribution shaping means integrated in a parallel arrangement.

The waveguides 33a to 33b use a transparent block having a pair of reflecting surfaces facing each other in the y-direction.
An opaque body or a transparent body having a smaller refractive index than that of the transparent block is interposed and integrated. Each condenser lens is arranged on the incident side of each transparent block, and the laser beams from the laser oscillators 1a to 1c are respectively The light enters between the reflective surfaces of the transparent blocks.

Also in this example, the laser beams 2a and 2b from the outer plurality of laser oscillators 1a and 1c out of the plurality of laser oscillators 1a to 1c that are appropriately separated from each other are supplied to the reflecting mirror M as in the above-described embodiment. Are adjusted to parallel laser beams at a narrow interval from each other, and are incident on each condenser lens 32.

In this embodiment, a plurality of waveguides 33a to 33a
Since the laser beams emitted from 3b are arranged in parallel with a distance from each other on the optical axis without being completely combined and integrated, a cylindrical lens is used as the beam shape shaping means 40, and the laser beam is emitted in the y direction. Is long and uniform in intensity distribution, x
A linear irradiation beam linearly converged in the direction can be obtained on the semiconductor film surface.

According to this embodiment, since the stop angle of each laser beam incident on the plurality of waveguides can be reduced, the divergence angle of the beam emitted from the intensity distribution shaping means 30 can also be reduced. 2, the beam shape shaping means 40 having a smaller numerical aperture NA can be used, and the number of optical components can be reduced in size and cost can be reduced.

Embodiment 3 On the radiation side of the intensity distribution shaping means 30 shown in the second embodiment, a plurality of waveguides 3
When the optical axes of the laser beams emitted from 3a, 33b, and 33c in the x direction coincide with each other, the irradiation laser beam 8 from the beam shape shaping unit 40 on the semiconductor film 5
FIG. 3 shows an example in which a, 8b, and 8c are linearly arranged in the y direction.

Since it is difficult for the intensity distribution shaping means 30 to make the shape intensity distribution in the y direction completely rectangular, the intensity distributions Pya, Pya, y in the y direction of each of the irradiation laser beams 8a, 8b, 8c.
For Pyb and Pyc, the periphery of the intensity distribution profile becomes gentle. Therefore, as shown in FIG. 3, the peripheral portion of the irradiation laser beam (eg, 8a) is appropriately overlapped with the peripheral portion of the adjacent irradiation laser beam (eg, 8b) as shown in FIG. By adjusting the interval between the wave paths 33a and 33b, the laser beams emitted from the plurality of laser oscillators can be almost uniformly combined on the semiconductor film in the y direction to have a uniform uniform combined intensity distribution Py. Yes, x
In the direction, a steep narrow width intensity distribution Px can be obtained.

In this embodiment, since a substantially uniform irradiation light intensity can be obtained in the length direction in the y direction, it is possible to form a uniform polycrystalline semiconductor film with large crystal grains, for example, a silicon film. By using the film, a thin film having excellent crystallinity required for manufacturing a high-performance thin film transistor can be formed.

Embodiment 4 FIG. FIG. 4 shows another example of the intensity distribution shaping means 3 as described in the second embodiment.
0, the plurality of waveguides 33a33b, 33
In the case where the optical axes in the x direction of the laser beam emitted from the laser beam c do not coincide, the irradiation laser beam 8 on the silicon film surface
a, 8b, and 8c are arranged so as not to overlap in the y-direction and alternately instead of in a straight line. When viewed from the scanning direction, as shown in FIG. Irradiating laser beam adjacent to it (for example)
8b so as to appropriately overlap with the region 81 of uniform irradiation intensity,
The distance between the waveguides 33a and 33b is adjusted as shown in FIG. Accordingly, in the process of scanning the plurality of laser beams emitted from the plurality of laser oscillators on the semiconductor film, the regions 81, 81 of the uniform intensity distribution Py of the irradiation laser beam in the y direction are provided.
Can be overlapped with each other, and an intensity distribution Px having a steep narrow width in the x direction can be obtained. This example
Since the irradiation laser beam does not overlap with other irradiation laser beams, a portion having a high irradiation intensity does not occur locally, and it is possible to prevent the silicon film from being damaged by the high laser intensity.

[0044]

According to the laser optical system for laser annealing of the present invention, a laser beam emitted from a laser
An intensity distribution shaping means for irradiating an amorphous or polycrystalline semiconductor film surface formed on a substrate and for irradiating an irradiation laser beam on the semiconductor film surface with a linear shape; A plurality of laser beams from the oscillator are made incident on the intensity distribution shaping unit, and the intensity distribution shaping unit uniformly lengthens the intensity distribution of each irradiation laser beam in one direction and sharply narrows in the orthogonal direction. The irradiation laser beam can increase the irradiation area while maintaining the required irradiation intensity, thereby improving the productivity of the polycrystalline semiconductor film. The number can be reduced.

In the laser optical system, since the intensity distribution shaping means uses a single waveguide for a plurality of laser oscillators, the irradiation laser beam can maintain the required irradiation intensity, increase the irradiation area, and increase the production area. Performance can be improved, the number of optical components can be reduced, and downsizing and cost reduction can be achieved.

In the laser optical system according to the present invention, if the intensity distribution shaping means uses a plurality of waveguides corresponding to a plurality of laser oscillators, the aperture angle of the laser beam incident on the waveguide can be reduced, so that the intensity The divergence angle of the beam emitted from the distribution shaping means can be reduced, and a beam shape shaping means having a small aperture ratio can be used, so that the number of optical components can be reduced and the cost can be reduced.

In the laser optical system of the present invention, if a cylindrical lens is used as a beam shape shaping means, a narrow irradiation laser beam can be formed on a semiconductor film with a simple optical component. The solidification process can be unidirectionally solidified to form large crystal grains over the wide irradiation area.

In the laser optical system, if a plurality of intensity distribution shaping means arrange the formed irradiation laser beams in a substantially straight line in the longitudinal direction, the irradiation laser beam can obtain a substantially uniform irradiation light intensity in the longitudinal direction. Thus, a uniform polycrystalline silicon film can be formed, and a thin film having excellent crystallinity required for manufacturing a high-performance thin film transistor can be formed.

In the laser optical system, if the irradiation laser beams formed by the plurality of intensity distribution forming means are arranged so as not to overlap with each other, a portion having a high irradiation intensity does not occur locally.
The high laser intensity can prevent the amorphous or polycrystalline silicon film from being damaged.

When the laser optical system of the present invention is applied to a silicon film as a semiconductor film, a high-speed and high-performance thin film transistor can be formed, and can be used as a pixel portion of a high-performance liquid crystal display.

In the laser optical system of the present invention, if a laser oscillator having an oscillation wavelength between 320 nm and 800 nm is used, in particular, the thickness direction of the amorphous or polycrystalline silicon film is uniformly heated. As a result, a thin film having excellent crystallinity required for manufacturing a high-performance thin film transistor by a laser heat treatment method can be obtained.

In the laser optical system of the present invention, the laser oscillator can be made compact if the harmonics of the solid-state laser are used, and if the harmonics are within the above wavelength range,
The thickness direction of the amorphous or polycrystalline silicon film can be uniformly heated, and a thin film having excellent crystallinity required for manufacturing a high-performance thin film transistor can be obtained.

The laser annealing apparatus includes the laser optical system described above, a laser oscillator for emitting a laser beam to the laser optical system, a stage for mounting and fixing a substrate, and an irradiation laser beam provided for the optical system or the stage. A scanning mechanism that scans the semiconductor film in the orthogonal direction as described above, so that the irradiation area can be increased, the productivity can be improved, and the high-performance thin film transistor can be manufactured while maintaining the required irradiation intensity. A thin film having excellent crystallinity can be obtained, the device configuration can be simplified, and the number of optical components can be reduced.

[Brief description of the drawings]

FIG. 1 is a side view of a laser optical system according to an embodiment of the present invention (A, B).

FIG. 2 is a side view (A, B) of a laser optical system showing another embodiment of the present invention.

FIG. 3 shows an intensity distribution of an irradiation laser beam on a semiconductor film in the embodiment of the present invention.

FIG. 4 shows an intensity distribution of an irradiation laser beam on a semiconductor film according to another embodiment of the present invention.

FIG. 5 shows a configuration diagram (A, B) showing a laser heat treatment apparatus and intensity distributions (C to E).

[Explanation of symbols]

REFERENCE SIGNS LIST 1 laser oscillator, 2 laser beam, 30 intensity distribution shaping means, 5 silicon film, 6 substrate, 32 lens, 3
3 waveguide, 40 beam shaping means, 8a, 8b,
8c Irradiation laser beam.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yukio Sato 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation (72) Inventor Junichi Nishimae 2-3-2 Marunouchi, Chiyoda-ku, Tokyo F term in Mitsubishi Electric Corporation (reference) 5F052 BA01 BA04 BA07 BA14 BA15 BB02 BB07 CA07 CA10 DA01 DB02 JA01 5F110 AA16 AA30 DD01 DD02 DD13 GG02 GG15 GG25 GG47 PP03 PP04 PP05 PP06 PP07 PP29

Claims (10)

[Claims] 1. A laser optics for laser annealing including an intensity distribution shaping means and a beam shape shaping means for irradiating a laser beam emitted from a laser oscillator to a surface of an amorphous or polycrystalline semiconductor film formed on a substrate. The intensity distribution shaping means, wherein a plurality of laser beams from a plurality of laser oscillators are incident, and the intensity distribution of each irradiation laser beam irradiated on the semiconductor film surface is perpendicular to the optical axis of the laser beam. The beam shape shaping means makes the intensity distribution of each irradiation laser beam sharply narrow in a direction orthogonal to the one direction, and the semiconductor laser is irradiated with the linear irradiation laser beam. A laser optical system that melts and polycrystallizes a film. 2. The intensity distribution shaping means includes a single waveguide having a pair of opposed reflecting surfaces that alternately reflect a plurality of laser beams incident from a plurality of laser oscillators in the one direction. 4. The laser optical system according to 1. 3. The apparatus according to claim 1, wherein the intensity distribution shaping means includes a plurality of waveguides having a pair of opposed reflecting surfaces reflecting in one direction corresponding to each laser beam from the plurality of laser oscillators. Laser optics. 4. The apparatus according to claim 1, wherein said beam shape shaping means includes a cylindrical lens which converges the laser beam from the intensity distribution shaping means in the orthogonal direction to make the irradiation laser beam a narrow linear beam. A laser optical system as described. 5. The laser optical system according to claim 3, wherein a plurality of irradiation laser beams formed on the semiconductor film by providing a plurality of waveguides are arranged substantially linearly in the one direction. 6. An irradiation laser beam formed on a semiconductor film by the plurality of waveguides is alternately arranged in the one direction, and adjacent irradiation laser beams do not overlap with each other. The laser optical system according to claim 3. 7. The laser optical system according to claim 1, wherein said semiconductor film is a silicon film. 8. The laser beam has a wavelength of 320 to 800 n.
The laser optical system according to any one of claims 1 to 7, wherein the laser optical system is a pulse laser having an oscillation wavelength in a range of m. 9. The laser optical system according to claim 8, wherein the laser beam is a harmonic of a solid-state laser. 10. The laser optical system according to claim 1, a laser oscillator for emitting a laser beam to the laser optical system, a stage for mounting and fixing a substrate, and the optical system or the stage. A scanning mechanism for scanning the semiconductor laser with the irradiation laser beam in the orthogonal direction.