JP2005311346A - Laser annealing method and laser annealing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide laser annealing method/device, with which a part is iterrupted where the energy intensity of a laser beam is weak, irradiation face is irradiated with a linear laser beam and the irradiation face is irradiated with the linear beam of uniform intensity. <P>SOLUTION: The laser beams, ejected from a laser oscillator 101, are made to pass through slits 102, the part where intensity is weak is interrupted and the beams are deflected by a mirror 103. Images formed in the slits are projected to the irradiation face 106 by a convex type cylindrical lens 104, and the irradiation face are irradiated with the linear beam with uniform intensity so as to perform laser annealing. An interval (M1) between the slit and the convex type cylindrical lens, and an interval (M2) between the convex type cylindrical lens and the irradiation face satisfy relational Formula (1) and Formula (2); where M1=f(s+D)/D, Formula (1) and M2=f(s+D)/s, Formula (2). In the Formulas, (s) is width of the slit, D is length of a long side direction of the linear beam, and (f) is the focal distance of the convex type cylindrical lens. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a laser annealing method and a laser annealing apparatus capable of irradiating a linear beam having a uniform intensity on an irradiation surface suitable for crystallization of an amorphous semiconductor film.
In more detail, the present invention is capable of irradiating linear laser light on the irradiated surface by blocking a low energy density portion of the laser light and generating no fringes due to light diffraction on the irradiated surface. The present invention relates to a laser annealing method and a laser annealing apparatus suitable for crystallization of an amorphous semiconductor film that irradiates a linear beam having a uniform energy density, that is, a uniform intensity.

In recent years, a technique for manufacturing a thin film transistor (hereinafter referred to as TFT) on a substrate has greatly advanced, and application development to an active matrix display device has been advanced.
In particular, a TFT using a polycrystalline semiconductor film has higher field effect mobility (also referred to as mobility) than a conventional TFT using an amorphous semiconductor film, and thus can operate at high speed.
For this reason, attempts have been made to control a pixel, which is conventionally performed by a driving circuit provided outside the substrate, using a driving circuit formed on the same substrate as the pixel.

By the way, as a substrate used for a semiconductor device, a glass substrate is considered promising rather than a quartz substrate in terms of cost.
Since glass substrates are inferior in heat resistance and easily deformed by heat, when forming TFTs using a polycrystalline semiconductor film on a glass substrate, a laser is used to crystallize the semiconductor film to avoid thermal deformation of the glass substrate. Annealing is used.

The characteristics of laser annealing are that the processing time can be significantly shortened compared to annealing methods using radiation heating or conduction heating, and the semiconductor substrate or semiconductor film is selectively and locally heated to make the substrate almost thermally It is mentioned that it will not be damaged.
The laser annealing method here refers to a technique for annealing a damaged layer or an amorphous layer formed on a semiconductor substrate or semiconductor film, or a technique for crystallizing an amorphous semiconductor film formed on a substrate. Yes.
It also includes techniques applied to planarization and surface modification of semiconductor substrates or semiconductor films.

Laser oscillators used for laser annealing are roughly classified into two types, pulse oscillation and continuous oscillation, depending on the oscillation method.
In recent years, in crystallizing a semiconductor film, it is more preferable to use a continuous oscillation laser oscillator such as an Ar laser or a YVO ₄ laser than a pulse oscillation laser oscillator such as an excimer laser. It has been found that the diameter increases.
As the crystal grain size in the semiconductor film increases, the number of grain boundaries entering the TFT channel region formed using the semiconductor film decreases, so the carrier mobility increases, which can be used for the development of higher performance devices. Therefore, continuous wave laser oscillators are in the spotlight.

For laser annealing of a semiconductor film, a laser beam having a visible or ultraviolet wavelength is often used.
This is because the absorption efficiency into the semiconductor film is good.
However, the wavelength oscillated from a solid laser medium generally used for a CW (continuous oscillation) laser is from the red to the near infrared region, and these wavelength regions have low absorption efficiency into the semiconductor film. Used to convert to a harmonic having a wavelength below the visible range.
In general, a method of converting a near-infrared fundamental wave that easily obtains a large output into a green laser beam that is the second harmonic has the highest conversion efficiency and is frequently used.

For example, when a 10 W, 532 nm CW laser beam is shaped into a linear shape of about 300 μm in the long side direction and about 10 μm in the short side direction, and the semiconductor film is crystallized by scanning the linear beam in the short side direction, The width of the large grain crystal region obtained by scanning is about 200 μm (hereinafter, a region where large grain crystals are seen is referred to as a large grain crystal region).
Therefore, in order to crystallize all of the semiconductor film formed on the entire surface of a relatively large substrate with a CW laser beam, the width of the large grain crystal region obtained by one scanning of the linear beam is increased by a linear shape. It is necessary to perform laser annealing by shifting the beam scanning position in the long side direction.

On the other hand, when the energy at both ends in the long side direction of the linear beam is attenuated simultaneously with the formation of the large grain crystal region, a crystal region that is not the large grain crystal region (hereinafter referred to as a poor crystallinity region) is formed.
Concavities and convexities are conspicuous on the surface of the poor crystallinity region and are unsuitable for producing TFTs, and when TFTs are formed there, it causes variations in electrical characteristics and malfunctions.
For this reason, when manufacturing a highly reliable TFT, it is necessary to accurately position the TFT when irradiating the laser beam so that the TFT is not formed in the poorly crystalline region.
However, even if such consideration is taken into account, there is a problem that the region of poor crystallinity expands as the length of the linear beam in the long side direction becomes longer.

As a result, a region where TFTs can be formed over the entire substrate is reduced, and it becomes difficult to manufacture a highly integrated semiconductor device.
The above problem is considered to be caused by the fact that the intensity distribution of the laser beam used is Gaussian.
In the Gaussian distribution, the central portion of the beam spot has the strongest intensity, and the intensity gradually decreases as the tail is drawn.
For this reason, when the linear beam is shaped and an attempt is made to lengthen the long side direction, the skirt portion extends along with it, resulting in a wide crystallinity defect region.

In order to reduce this, there is a method in which the intensity distribution of the laser beam is not a Gaussian shape but a top flat type.
As a method for making the top flat, a method using a diffractive optical element or an optical waveguide is introduced in a catalog of a laser equipment manufacturer.
By making the top flat, the skirt portion in the distribution of the laser beam can be made steep, and the defective crystallinity region formed after laser annealing can be extremely reduced.
Further, by making the top flat, even if the longer side direction of the linear beam becomes longer, it becomes possible to reduce the crystalline defect region.

As described above, there is an advantage in the method of making the top flat, but the method using the diffractive optical element requires fine processing on the nanometer order in order to obtain good characteristics, and is technically difficult. Many are expensive.
Further, when an optical waveguide or the like is used, the laser beam having a wavelength of 532 nm has strong coherence, so that the intensity of the laser beam appears on the irradiated surface as interference fringes.

As described above, there is a problem in the method of making the top flat, which is a technique for avoiding the disadvantages caused by the Gaussian distribution. Therefore, another technique for avoiding the disadvantages caused by the Gaussian distribution is described in this document. The inventors have developed and have already filed a patent application (Japanese Patent Application No. 2004-58378).
It is a technique of blocking the skirt portion of the Gaussian distribution using a slit before the laser beam is irradiated.
This method makes it possible to reduce the poorly crystalline region by blocking only the weak laser beam in the portion where the poorly crystalline region is formed and using only the laser beam having a large grain size crystalline region. However, even with this method, it has been found that when the laser beam passes through the slit, diffraction fringes appear on the irradiated surface, and the formation of the poorly crystalline region cannot be completely avoided.

The present inventors have earnestly developed a technique for avoiding the appearance of fringes due to diffraction in a method of performing laser annealing with a linear laser beam by blocking the bottom of the Gaussian distribution with a slit and having a weak laser beam energy intensity. As a result of the research and development, the present invention has been successfully developed.
Therefore, according to the present invention, a portion having a low energy density of the laser beam is blocked by a slit, and a linear beam having a uniform intensity is irradiated on the irradiation surface without generating a fringe due to light diffraction on the irradiation surface. An object to be solved, ie, an object, is to provide a laser annealing method and a laser annealing apparatus suitable for crystallization of a crystalline semiconductor film.

Another object of the present invention is to provide a crystalline semiconductor film having no poor crystallinity region based on fringes generated by diffraction, and a method and apparatus for manufacturing a TFT including the crystalline semiconductor film by a simple technique.
Furthermore, simply speaking, it is an object of the present invention to eliminate a defective crystallinity region during laser annealing by a simple method without causing fringes due to diffraction.

In connection with the above-mentioned problem to be solved of the present invention, first, a phenomenon in which diffraction that causes fringes will occur will be described.
Let us consider a Fraunhofer diffraction image generated when a plane wave is incident on a slit-shaped opening having a distance L between the slit and the image plane, a wave number k, a wavelength λ, and a width w.
At this time, the displacement of light on the slit surface is expressed by the following equation (A-1) as a function of the coordinates ξ and η at the opening.
Further, the complex amplitude u on the displacement image plane of light at that time can be expressed by the following formula (A2) as a function of x, and the light intensity I is expressed by the following formula (A3).
At this time, the center of the slit is x = 0.
Furthermore, X which is the reciprocal of the length is represented by the following formula (A4).

The intensity distribution given by these functions takes a maximum value of 1 when X = 0, and most of the laser light is concentrated in the center.
This peak at the center is called 0th-order diffracted light, which corresponds to light that travels straight from the slit along the optical axis.
The bright part around the center is called ± 1st order, ± 2nd order,... Diffracted light in order.
The position where the (m ≠ 0) intensity of the ± mth-order diffracted light takes the maximum value is approximately the following expression (A5), which is converted to expression (Az).

As described above, the present invention is capable of irradiating the irradiated surface with linear laser light without blocking the low energy density portion of the laser light and without generating fringes due to light diffraction on the irradiated surface. The present invention provides a laser annealing method and a laser annealing apparatus that are suitable for crystallization of an amorphous semiconductor film or the like that are irradiated with a linear beam.
The laser annealing method is roughly classified into two methods. The first method is to pass a laser beam emitted from a laser oscillator through a slit to cut off a portion having a low energy density, and on the laser beam passing line. The image formed in the slit is projected onto the irradiation surface by a convex cylindrical lens or a convex spherical lens and irradiated.

At that time, the distance (M1) between the slit and the convex cylindrical lens or convex spherical lens and the distance (M2) between the convex cylindrical lens or convex spherical lens and the irradiation surface are preferably the following formulas (1) and (1): It is preferable to arrange them so as to satisfy the relationship (2).
M1 = f (s + D) / D Formula (1)
M2 = f (s + D) / s Formula (2)
(Where, s is the width of the slit, D is the length of the long side direction of the linear beam, and f is the focal length of the convex cylindrical lens or convex spherical lens.)
Thereby, the image in the slit is projected onto the irradiation surface by the convex cylindrical lens.
Since the image in the slit corresponds to the case of L = 0 in the formula (A4), no fringes due to diffraction occur at this position.
Accordingly, no stripes are generated on the irradiation surface onto which the slit image is projected.

In the second method, laser light emitted from a laser oscillator is incident from a direction inclined by a mirror by a mirror, passes through a first convex spherical lens, and forms linear laser light by astigmatism, After that, a portion where the energy density of the linear laser beam is low is blocked by the slit, and the irradiation surface arranged at a position where the image of the linear laser beam in the slit can be projected using the second convex spherical lens is irradiated. Preferably, the distance (M1) between the slit and the second convex spherical lens and the distance (M2) between the second convex spherical lens and the irradiation surface are the following formulas (1) and ( They should be arranged so as to satisfy the relationship of 2).
M1 = f (s + D) / D Formula (1)
M2 = f (s + D) / s Formula (2)
(Where, s is the width of the slit, D is the length of the long side direction of the linear beam, and f is the focal length of the second convex spherical lens.)

  The laser annealing apparatus can be roughly divided into two as in the laser annealing method. The first laser annealing apparatus passes a laser oscillator and a laser beam emitted from the oscillator and blocks a portion having a low energy density. It is characterized by comprising a slit, and a convex cylindrical lens or convex spherical lens that projects an image formed on the slit on the passing line of the laser light with the lower portion blocked, and is preferably a spherical surface lens. Is the distance (M1) between the slit and the convex cylindrical lens or the convex spherical lens, and the distance (M2) between the convex cylindrical lens or the convex spherical lens and the irradiation surface are the above-described expressions (1) and (2). It is better to arrange them to satisfy the relationship.

The second laser annealing apparatus includes a laser oscillator, a mirror inclined at a predetermined angle that guides laser light emitted from the oscillator to a convex spherical lens, and a laser beam reflected by the mirror that passes through the linear shape due to astigmatism. A first convex spherical lens that forms laser light, a slit that blocks a low energy density portion of the linear laser light, and a second convex type that projects an image of the linear laser light in the slit onto the irradiation surface A spherical lens, and preferably an interval (M1) between the slit and the second convex spherical lens and an interval between the second convex spherical lens and the irradiation surface ( It is preferable to arrange them so that M2) satisfies the relationship of the above formulas (1) and (2).

The present invention uses a slit to block a low-energy part of the laser beam, and projects an image formed on the slit on the passing line of the laser beam from which the low part is blocked onto the irradiation surface using a lens. Thus, the appearance of interference fringes due to light diffraction in the slit can be avoided on the irradiated surface.
Therefore, the irradiation surface can be irradiated with a linear laser beam having no interference fringes due to light diffraction, and suitable laser annealing can be performed in crystallization of an amorphous semiconductor film.
Further, by utilizing the present invention, a semiconductor device such as a TFT having uniform crystallinity can be easily manufactured.

In the following, the present invention will be described with reference to embodiments including the best mode for carrying out the invention. However, the present invention is not limited thereby, and is specified by the description of the scope of claims. Needless to say.
The present invention has the invention-specific matters as described above, and its features are simply as follows. It uses a slit to block the low energy density portion of the laser beam, and the low portion of the laser beam is cut off. The image formed in the slit on the light passing line is projected onto the irradiation surface by the lens.

Further, as described above, the present invention can be broadly divided into two types, that is, a first laser annealing method using a convex cylindrical lens and a second laser annealing method using a convex spherical lens.
Further, in the first laser annealing method, the laser beam is perpendicularly incident on the irradiation surface of the first embodiment shown in FIGS. 1 and 2 and the oblique incidence on the same surface of the second embodiment shown in FIG. There are two ways to do this.

The position where the slit is inserted is determined by the focal length of the lens used as the projection means, the width of the slit, and the projection magnification.
Since the position of the slit corresponds to L = 0 in the formula (Az), if the image formed in the slit can be transferred using a lens and projected completely, the higher-order diffracted light can be made as small as possible. it can.
Accordingly, it is possible to produce a large grain crystal region without transmitting a fringe due to diffraction to the irradiated surface only at an appropriate position of the slit, lens and irradiated surface.
In other words, laser irradiation can be performed without forming fringes due to diffracted light that makes the energy density of the linear laser light nonuniform.

The laser oscillator used in the present invention is not particularly limited, and either a pulse oscillation or a continuous oscillation laser oscillator can be used. As a pulse oscillation laser oscillator, an excimer laser, a YAG laser, or a YVO _{4 is used.} Examples of the laser oscillator include an Ar laser, a YVO ₄ laser, and a YAG laser.
In the present invention, the laser light emitted from the laser oscillator may travel straight to the slit. However, it is more optical to place a mirror between the laser oscillator and the slit to deflect the laser light traveling direction and guide it to the slit. This is preferable because the adjustment can be made accurately.

When a laser that oscillates continuously is used for the laser oscillator, the grain size of crystals formed in the semiconductor film increases, and the number of grain boundaries entering the TFT channel region formed using the semiconductor film decreases. As a result, the carrier mobility becomes high and can be used for the development of a higher-performance device. However, the use of a solid-state laser is particularly preferable in terms of stability of laser output.
Further, the wavelength oscillated from a solid laser medium used for a CW (continuous wave) laser is generally from red to the near-infrared region, and these wavelength regions have low absorption efficiency into a semiconductor film, and therefore, a nonlinear optical element. It is better to convert to a harmonic having a wavelength below the visible range using.
In this case, it is best to convert the near-infrared fundamental wave, which is easy to obtain a large output, into a green laser beam, which is the second harmonic, with the highest conversion efficiency.

The slit used in the present invention is not particularly limited, and various structures or shapes can be used as long as the portion having a low energy density can be blocked when passing through the slit. Although a prism etc. can be illustrated, a reflector is preferable at the point of durability.
Similarly, the convex cylindrical lens to be used is not particularly limited, and various structures or shapes can be used as long as a long beam extending only in one direction can be formed.
As such a convex cylindrical lens, a convex surface may be formed on either the incident side or the output side, or may be formed on both. Of course, it is incident in terms of low aberration and accuracy. What has the convex surface formed in the side is good.

In the second laser annealing method and apparatus of the present invention, a convex spherical lens is used instead of the convex cylindrical lens used in the first laser annealing method and apparatus. There is no particular limitation, and various structures or shapes can be used as long as the long laser beam formed by the slit can be projected onto the irradiation surface. Similarly to the convex cylindrical lens, it may be formed on one or both of the incident side and the emission side.
The second laser annealing method and apparatus of the present invention are shown in FIGS. 4 and 5 and will be described in detail in Example 3.

Next, regarding the present invention, the outline of the best mode for carrying out the invention will be described first with reference to FIG.
In FIG. 1, laser light is emitted from a laser oscillator 101 of mode-locked pulse oscillation with CW or a repetition frequency of 10 MHz or more. The laser light is blocked by a slit 102 at a portion where the energy density of the laser light is low, and by a mirror 103. It is deflected in the direction of the semiconductor film 106.

The deflected laser beam is a convex cylindrical lens that acts only in one direction (in the following description in the "Best Mode for Carrying Out the Invention" column and in the description of Examples, unless otherwise required, The image of the slit 102 is elongated and projected onto the semiconductor film 106 that is the irradiation surface.
Since the cylindrical lens acts only in one direction as described above, the previous laser light is condensed by the cylindrical lens 105 acting only in one direction rotated 90 degrees with the cylindrical lens 104 and is applied to the semiconductor film 106. Irradiated.

In this case, the cylindrical lens 104 acts only in the long side direction of the linear beam on the irradiation surface, and the cylindrical lens 105 acts only in the short side direction.
That is, the laser light whose length in the long side direction is changed by the cylindrical lens 104 is not changed in length in the long side direction depending on the cylindrical lens 105, and only the length in the short side direction is changed. Become.

These will be described in more detail with reference to FIG.
The numbers in FIG. 2 are also the same as those used in FIG.
2 (a) is a top view in FIG. 1, showing an optical path acting in the major axis direction of the linear beam on the irradiation surface, and FIG. 2 (b) is a side view in FIG. The minor axis direction of the beam is shown.
The laser beam emitted from the laser oscillator 101 is partially blocked by the slit 102, and only a portion where the intensity of the laser beam is strong passes.
The laser beam that has passed through the cylindrical lens 104 projects an image formed by the slit 102 onto the semiconductor film 106.

Here, the positional relationship between the cylindrical lens 104 employed in the present invention, the slit 102, and the semiconductor film 106 serving as an irradiation surface will be described in detail using equations.
The symbols used at that time are as follows.
The focal length of the cylindrical lens 104 is f, and the width of the slit 102 is s.
At this time, the interval between the slit 102 and the cylindrical lens 104 is M1, and the interval between the cylindrical lens 104 and the semiconductor film 106 is M2.
In addition, the length in the long side direction on the semiconductor film 106 to be the irradiation surface is D.

When these symbols are used, the following two expressions are established for the positional relationship.
s / D = M1 / M2 Formula (a)
1 / f = 1 / M1 + 1 / M2 Formula (b)
Furthermore, the relationship of the following formula is established from these two formulas.
M1 = f (s + D) / D Formula (1)
M2 = f (s + D) / s Formula (2)

Therefore, by arranging the slit, the cylindrical lens, and the irradiation surface at a position that satisfies these relationships, the intensity of light due to diffraction is not transmitted to the semiconductor film.
As a result, it is possible to perform laser irradiation that hardly forms a poorly crystalline region, and it is preferable to satisfy these relationships.
Furthermore, instead of the cylindrical lens, a convex spherical lens having the same focal length f may be used.
In this case, since the convex spherical lens also acts in the short side direction of the linear beam, it is preferable to add a lens that compensates for it.

In the present invention, there is also the second laser annealing method shown in FIGS. 4 and 5 that uses a convex spherical lens without using a cylindrical lens in addition to the above, but the same relationship also holds in that case. .
That is, as described in Embodiment 3, the same relationship holds for the positional relationship among the slit 404, the second convex spherical lens 405, and the semiconductor film 406.
Specifically, the positional relationship between the distance (M1) between the slit 404 and the second convex spherical lens 405 and the distance (M2) between the second convex spherical lens 405 and the semiconductor film 406 is expressed by the above formula ( The relations 1) and (2) hold.
In this case, however, f is the focal length of the second convex spherical lens in the above equation.

Next, laser annealing according to the present invention will be described with reference to FIG.
A laser beam emitted from a laser oscillator 101 is set on an X stage 108 and a Y stage 109 on which a glass substrate 107 on which a semiconductor film 106 to be an irradiation surface is formed can be moved at a speed of 100 to 1000 mm / sec. In the present invention, large-grain crystals are formed on the entire surface of the substrate by scanning and moving at an appropriate speed while irradiating.
The optimum scanning speed expected from the inventors' experience is around 400 mm / sec.
A semiconductor film in which a crystal having a large grain size is formed by such a method can be used to manufacture a TFT by using well-known means, and a high-speed device can be manufactured.

In the following, the present invention will be described in more detail with reference to Examples 1 to 5. However, the present invention is not limited by these Examples, and is specified by the description of the scope of claims. Needless to say.
First, a case in which vertical incidence is performed using a mode-locked pulse laser and two cylindrical lenses will be described below as Example 1.

[Example of normal incidence using a mode-locked pulse laser and two cylindrical lenses]
The first embodiment is an embodiment of the first laser annealing method and apparatus, and is an embodiment in which a laser beam with a low intensity portion cut off is perpendicularly incident on the irradiation surface. It explains using.
In this embodiment, the laser oscillator 101 is a mode-locked pulse laser oscillator having an output of 10 W, a repetition frequency of 80 MHz, a pulse width of 10 psec, a wavelength of 532 nm, a beam diameter of 2.25 mm, and a beam quality TEM ₀₀ .

The laser light emitted therefrom is blocked by the slit 102 at a portion where the energy density of the laser light is low, and is deflected in the vertical direction by the mirror 103 with respect to the semiconductor film 106 formed on the glass substrate 107.
In order to improve the resistance of the a-Si film to the laser beam after forming the a-Si film on the glass substrate 107 having a thickness of 0.7 mm to a thickness of 660 mm using a CVD apparatus. In addition, a furnace annealed in a nitrogen atmosphere of 500 degrees for 1 hour was used.
The interval between the slits 102 was 0.8 mm.

The deflected laser light vertically projects an image of the slit 102 onto the semiconductor film 106 that is an irradiation surface by a cylindrical lens 104 that acts only in one direction.
Further, the laser light is condensed by the cylindrical lens 104 and the cylindrical lens 105 that acts only in one direction with the convex surface rotated 90 degrees, and is irradiated to the semiconductor film 106.
Therefore, the cylindrical lens 104 acts only in the long side direction of the linear beam on the irradiation surface, and the cylindrical lens 105 acts only in the short side direction.
In addition, the length of the long side direction of the linear beam shaped on the semiconductor film 106 used as an irradiation surface was 0.2 mm, and the cylindrical lenses 104 and 105 having focal lengths of 150 mm and 20 mm, respectively, were used.

Further, in the first embodiment, since an ultrashort pulse laser beam is used, there is no influence of light interference between the reflected light from the back surface of the glass substrate and the incident light, and the crystallinity is formed on the semiconductor film 106. Can be avoided.
That is, when affected by the interference of these two lights, the intensity of the laser light appears as a stripe, and the crystal variation greatly occurs on the semiconductor film 106 after annealing.
This will be further discussed below.

As described above, the pulse width of the laser light in Example 1 is 10 psec, and the distance traveled by one pulse of laser light is about 3 mm.
In this embodiment, a glass substrate 107 having a thickness of 0.7 mm is used. As a result, the distance from which incident light is reflected by the back surface of the glass substrate 107 and returns to the surface of the glass substrate 107 again. Is 1.4 mm, and the time during which incident light and reflected light from the back surface of the glass substrate 107 are simultaneously mixed in the semiconductor film 106 is about half of the pulse width.
Therefore, in Example 1, laser annealing can be performed without being greatly affected by light interference.

In the present invention, since the positional relationship between the cylindrical lens 104, the slit 102, and the semiconductor film 106 serving as an irradiation surface preferably satisfies the above formulas (1) and (2), the present embodiment is implemented to satisfy this. In Example 1, the positional relationship was as follows.
As described above, the focal length of the cylindrical lens 104 is 150 mm, the slit width is 0.8 mm, and the length of the linear beam to be shaped on the semiconductor film 106 to be irradiated is 0.2 mm in the long side direction. The distance (M1) between the slit 102 and the cylindrical lens 104 and the distance (M2) between the cylindrical lens 104 and the semiconductor film 106 necessary to satisfy the above (1) and (2) were obtained.

The result is as follows.
M1 = f (s + D) / D = 150 × (0.8 + 0.2) /0.2=750 mm
M2 = f (s + D) / s = 150 × (0.8 + 0.2) /0.8=187.5 mm
Therefore, in this embodiment, the slit 102, the cylindrical lens 104, and the irradiation surface 106 are disposed at positions that satisfy these relationships.

When the mode-locked pulse laser is emitted in this manner and irradiated onto the semiconductor film which is the irradiation surface, the fringes due to diffraction are not transmitted, and the laser light is uniformly irradiated and the width of the large grain crystal region is 0. At 2 mm, large-grained crystals were formed uniformly without uneven crystallinity regions.
As a result, in Example 1, it was possible to perform laser irradiation in which almost no poor crystallinity region was formed.

In this embodiment, the glass substrate 107 on which the semiconductor film 106 is formed is placed on the X stage 108 and the Y stage 109, and is scanned and moved at a speed of 400 mm / sec. I was able to make it.
A semiconductor film in which a crystal having a large grain size is formed by such a method can be used to manufacture a TFT by using well-known means, and a high-speed device can be manufactured.

[An example of oblique incidence using a CW laser and two cylindrical lenses]
Example 2 is also an example of the first laser annealing method and apparatus. In this example as well, a cylindrical lens is used similarly to Example 1, but the CW different from that of Example 1 is used for the laser oscillator. A laser is used, which is different from the first embodiment.
That is, the second embodiment is an embodiment of the first laser annealing method and apparatus, but is different from the first embodiment, and is irradiated with a laser beam whose portion having a low energy density is cut off. The light is incident obliquely on the surface, and the second embodiment will be described first with reference to FIG.

In this embodiment, the laser oscillator 301 is a CW laser oscillator having an output of 10 W, a wavelength of 532 nm, a beam diameter of 2.25 mm, and a beam quality TEM ₀₀ .
The laser light emitted therefrom is blocked by the slit 302 at a portion where the energy density of the laser light is low, and is deflected in a direction oblique to the surface of the semiconductor film 306 formed on the glass substrate 307 by the mirror 303. .
The semiconductor film 306 is formed in order to improve the resistance of the a-Si film to a laser beam after the a-Si film is formed on the glass substrate 307 having a thickness of 0.7 mm to a thickness of 660 mm using a CVD apparatus. In addition, a furnace annealed in a nitrogen atmosphere of 500 degrees for 1 hour was used.
The interval between the slits 302 is 0.8 mm.

The deflected laser light obliquely projects the image of the slit 302 onto the semiconductor film 306 that is the irradiation surface by the cylindrical lens 304 that acts only in one direction.
Further, the laser light is condensed by the cylindrical lens 305 that rotates 90 degrees with the cylindrical lens 304 and acts only in one direction, and is irradiated onto the semiconductor film 306. Therefore, the cylindrical lens 304 acts only in the long side direction of the linear beam on the irradiation surface, and the cylindrical lens 305 acts only in the short side direction.
Note that the length of the linear beam shaped on the semiconductor film 106 serving as the irradiation surface is 0.2 mm in length, and the cylindrical lenses 304 and 305 have focal lengths of 150 m and 20 mm, respectively.

In the present invention, the positional relationship between the cylindrical lens 304, the slit 302, and the semiconductor film 306 serving as an irradiation surface preferably satisfies the above formulas (1) and (2). In Example 2, the positional relationship was as follows.
That is, the focal length of the cylindrical lens 304 is 150 mm, the slit width is 0.8 mm, and the length of the linear beam shaped on the semiconductor film 306 to be the irradiation surface is 0.2 mm in the long side direction. The distance (M1) between the slit 302 and the cylindrical lens 304 and the distance (M2) between the cylindrical lens 304 and the semiconductor film 306 necessary to satisfy (1) and (2) were obtained in the same manner as in Example 1. .

The result is the same as that of Example 1, and is as follows.
M1 = f (s + D) / D = 150 × (0.8 + 0.2) /0.2=750 mm
M2 = f (s + D) / s = 150 × (0.8 + 0.2) /0.8=187.5 mm
Therefore, in this embodiment, the slit, the cylindrical lens, and the irradiation surface are arranged at a position that satisfies these relationships.
When the semiconductor film which is the irradiation surface is irradiated with the CW laser emitted in this manner, the fringes due to diffraction are not transmitted, the laser beam is uniformly irradiated, and the width of the large grain crystal region is 0.2 mm. As a result, large grain crystals were uniformly formed without formation of poor crystallinity regions.
As a result, in Example 2, it was possible to perform laser irradiation in which almost no poor crystallinity region was formed.

In the second embodiment, the laser oscillator uses a CW laser. Therefore, in order to avoid interference between the reflected light from the back surface of the glass substrate 307 and the laser incident light on the semiconductor film 306, the reflected light is reflected. In order to prevent light and incident light from overlapping on the semiconductor film 306, the laser light needs to be incident on the semiconductor film 306 at a certain angle or more.
In this case, assuming that the length of the beam spot in the laser light incident direction is l, the laser light incident angle is θ, and the thickness of the glass substrate is d, the laser light incident angle satisfies the following formula. In this embodiment, the incident angle θ is set to 20 degrees.

なお、本実施例は、この点において実施例１とは異なっており、この点は本実施例の特徴点ともなっているが、逆にこの点の存在ゆえに第１のレーザアニール方法であるにもかかわらず、実施例１とは別の態様となっている。

The present embodiment is different from the first embodiment in this point, and this point is also a feature point of the present embodiment. However, this point is also the first laser annealing method due to the existence of this point. Regardless, the embodiment is different from the first embodiment.

In this embodiment, the glass substrate 307 on which the semiconductor film 306 is formed is placed on the X stage 308 and the Y stage 309 and scanned at a speed of 400 mm / sec. I was able to make it.
A semiconductor film in which a crystal having a large grain size is formed by such a method can be used to manufacture a TFT by using well-known means, and a high-speed device can be manufactured.

[An example of oblique incidence using a mode-locked pulse laser and two convex spherical lenses]
The third embodiment is an embodiment of the second laser annealing method and apparatus using a convex spherical lens instead of the cylindrical lens, which will be described with reference to FIG.
In this embodiment, the laser oscillator 401 is a mode-locked pulse laser oscillator 401 having an output of 10 W, a repetition frequency of 80 MHz, a pulse width of 10 psec, a wavelength of 532 nm, a beam diameter of 2.25 mm, and a beam quality TEM ₀₀ .
Laser light emitted therefrom is first deflected by the mirror 402.

The deflected laser light is incident on the first convex spherical lens 403 having a focal length of 20 mm from an oblique direction, and becomes linear on the slit 404 due to astigmatism of the lens.
The spot size of the linear laser beam is 0.04 mm in the minor axis direction and 1 mm in the major axis direction.
The interval between the slits 404 is set to 0.8 mm in the major axis direction, and the slits block portions having low energy density at both ends of the linear beam.
The blocked laser light is reduced and projected onto the semiconductor film 406 by a quarter size using a second convex spherical lens 405 having a focal length of 40 mm, and a short axis of 10 μm and a long axis are projected on the semiconductor film 406. A 200 μm linear beam is formed.

These will be described in more detail with reference to FIG. 5 showing a schematic diagram of the optical system of Example 3.
The numbers in FIG. 5 are also the same as those used in FIG.
FIG. 5 (a) is a top view in FIG. 4, in which an optical path acting in the major axis direction of the linear beam on the irradiation surface is shown, and FIG. 5 (b) is a side view in FIG. The minor axis direction of the beam is shown.
The semiconductor film 406 disposed on the irradiation surface is formed by forming an a-Si film on a glass substrate 407 having a thickness of 0.7 mm to a thickness of 660 mm using a CVD apparatus, and then lasing the a-Si film. In order to improve the resistance to the beam, a furnace annealed for one hour in a nitrogen atmosphere of 500 degrees was used.

In the present embodiment, as described above, the ultrashort pulse laser beam is used, and as a result, there is no adverse influence caused by the interference of the reflected light from the back surface of the glass substrate and the incident light.
Note that when affected by the interference of light, the intensity of the laser beam appears as a stripe, and the crystal variation greatly occurs on the semiconductor film 406 after annealing.
The light interference in this embodiment will be described in detail as follows.
In this embodiment, since the pulse width of the laser beam is 10 psec, the distance traveled by one pulse of laser beam during 10 psec is about 3 mm.

In this embodiment, the thickness of the glass substrate 407 is 0.7 mm, and the distance until the incident light is reflected by the back surface of the glass substrate 407 and returns to the surface of the glass substrate 407 is 1.4 mm. In addition, the time during which the incident light and the reflected light from the back surface of the glass substrate 407 are simultaneously mixed in the semiconductor film 406 is about half of the pulse width.
Therefore, laser annealing can be performed without being greatly affected by light interference.

In the second laser annealing method and apparatus of the present invention, the positional relationship between the second convex spherical lens 405 and the slit 404 and between the second convex spherical lens 405 and the semiconductor film 406 serving as an irradiation surface is as follows. As described above, since it is preferable to satisfy the above-described formulas (1) and (2), in order to satisfy this, the positional relationship in Example 3 is as follows.
As described above, the focal length of the second convex spherical lens 405 is 40 mm, the slit width is 0.8 mm, and the length of the linear beam to be shaped on the semiconductor film 406 to be the irradiation surface is 0.2 mm in the long side direction. Accordingly, based on them, the distance (M1) between the slit 404 and the second convex spherical lens 405 and the second convex spherical lens 405 and the semiconductor film necessary to satisfy the above-mentioned formulas (1) and (2) The interval (M2) of 406 was determined in the same manner as in the case of Example 1 and Example 2.

The result is as follows.
M1 = f (s + D) / D = 40 × (0.8 + 0.2) /0.2=200 mm
M2 = f (s + D) / s = 40 × (0.8 + 0.2) /0.8=50 mm
Therefore, in the present embodiment, the slit, the second convex spherical lens, and the irradiation surface are arranged at positions satisfying these relationships.

When the mode-locked pulse laser is emitted in this manner and irradiated onto the semiconductor film which is the irradiation surface, the fringes due to diffraction are not transmitted, and the laser light is uniformly irradiated and the width of the large grain crystal region is 0. At 2 mm, large-grained crystals were formed uniformly without uneven crystallinity regions.
As a result, in Example 3, it was possible to perform laser irradiation in which almost no poor crystallinity region was formed.

Also in this embodiment, the glass substrate 407 on which the semiconductor film 406 is formed is placed on the X stage 408 and the Y stage 409, and scanned and moved in the short side direction of the linear beam at a speed of 400 mm / sec. As a result, large grain crystals could be produced on the entire surface of the substrate.
A semiconductor film in which a crystal having a large grain size is formed by such a method can be used to manufacture a TFT by using well-known means, and a high-speed device can be manufactured.

Example 4 is an example in which the semiconductor film is crystallized using the laser irradiation method described in the above embodiment mode or examples, and this will be described below.
In addition, as a comparative example, a case where crystallization is performed using a conventional laser irradiation method is also shown.
In this example, the first laser annealing method and apparatus were used in the same manner as in Example 1 (see FIG. 1), and a method in which a laser beam with a low intensity cut off was perpendicularly incident on the irradiation surface was used. .

Here, a mode-locked pulse laser oscillator having an output of 10 W, a repetition frequency of 80 MHz, a pulse width of 10 psec, a wavelength of 532 nm, a beam diameter of 1.00 mm, and a beam quality TEM ₀₀ was used as the laser oscillator.
As a semiconductor film to be crystallized, an a-Si film is formed on a glass substrate having a thickness of 0.7 mm to a thickness of 66 nm using a CVD apparatus, and then a heat treatment is performed at 500 ° C. for 1 hour in a nitrogen atmosphere. Used.
Note that the heat treatment was performed in order to improve the resistance of the a-Si film to the laser beam.

The configuration of the optical system of the laser irradiation apparatus used at that time is the same as that of the first embodiment, and the laser beam emitted from the laser oscillator passes through the slit and acts in only one direction, respectively. The surface of the semiconductor film was irradiated vertically through a cylindrical lens.
Note that the first cylindrical lens acts only in the long side direction of the linear beam on the irradiation surface, and the second cylindrical lens acts only in the short side direction.

The slit width, the distance between the slit and the first cylindrical lens, and the distance between the first cylindrical lens and the semiconductor film are arranged so as to satisfy the expressions (1) and (2) shown in the above embodiment. .
Here, the slit interval is 0.8 mm, and the first cylindrical lens and the second cylindrical lens have focal lengths of 150 mm and 20 mm, respectively, and the long side of the beam spot irradiated on the semiconductor film is used. The length in the direction was 250 μm.

Then, the glass substrate provided with the semiconductor film was placed on the X stage and the Y stage, and the semiconductor film was crystallized by scanning and moving at a speed of 400 mm / sec.
An image of the surface of the semiconductor film at this time is shown in FIG.
From the image of FIG. 8, it was observed that when the semiconductor film was crystallized using the above laser irradiation apparatus, a large grain crystal region was formed on the entire surface irradiated with the laser beam.
Here, a large grain crystal having a width of 250 μm was formed.

In addition, in order to compare with the case of performing the above laser irradiation method, the semiconductor film was crystallized by a laser irradiation method different from the above method.
Here, crystallization was performed by irradiating the semiconductor film with laser light using two cylindrical lenses without providing a slit.
An image of the surface of the semiconductor film at this time is shown in FIG.
Here, as in FIG. 8, the output of the laser oscillator and the arrangement of the cylindrical lenses were adjusted under the condition that a large grain crystal having a width of 250 μm was formed on the semiconductor film.

In FIG. 9, a large grain crystal region having a width of 250 μm is formed on the surface of the semiconductor film, but it was observed that poorly crystalline regions were formed at both ends of the region irradiated with the laser beam.
This is because the laser light applied to the semiconductor film has a Gaussian intensity distribution, so that the semiconductor film is sufficiently melted by laser irradiation in the portions where the energy density of the laser light is low (both ends of the beam spot). I can't.

In other words, in the method in which the slit is not provided, the laser light applied to the semiconductor film has a Gaussian intensity distribution, so that the semiconductor film can be sufficiently melted in the portion irradiated with the strong laser light. Although the semiconductor film cannot be sufficiently melted in the portion irradiated with the laser beam having low intensity, a poor crystallinity region is formed.
On the other hand, in the laser irradiation method of the present embodiment, the semiconductor film is irradiated with the laser light that has passed through the slit through a lens that is arranged so as to satisfy a specific condition, thereby preventing generation of fringes due to diffraction of the laser light. Compared with the laser irradiation method in which no slit is provided, the poor crystallinity region can be reduced.

As shown in FIGS. 8 and 9, when forming a large grain crystal region having the same width, the conventional method (FIG. 9) has a wide crystalline defect region at both ends of the crystalline region. It is formed.
In the case of manufacturing a TFT using the semiconductor film irradiated with the laser, if such a crystallinity defect region is used for the active layer of the TFT, it causes variation in electrical characteristics and malfunction.
Therefore, it is necessary to form TFTs while avoiding the poorly crystalline region, and the presence of a wide defective crystalline region becomes a factor that prevents high integration.

On the other hand, when the laser irradiation method of this embodiment is used, almost no poor crystallinity regions are formed at both ends of the large grain crystal region as shown in FIG.
Therefore, the TFT can be formed on the substrate with almost no gap, and the TFT can be highly integrated.
In addition, when the laser irradiation method of this example is used, the variation in the energy density distribution of the linear beam is smaller than when crystallized by the conventional laser irradiation method. Variability has been improved.

Therefore, by using the laser irradiation method of this embodiment, variation in TFT characteristics can be reduced and device characteristics can be improved.
As described above, by using a combination of a slit, two cylindrical lenses, and a high-power laser oscillator as in this embodiment, it is possible to enlarge a large grain crystal region without enlarging a poor crystallinity region. It is possible to produce a wide crystal grain region having a wide width without causing a large crystal variation on the film surface.
Therefore, when the laser irradiation apparatus of this embodiment is used, TFT characteristics can be improved and TFTs can be highly integrated.

In this embodiment, laser irradiation is performed on a substrate in which an a-Si film is formed on a glass substrate, but the structure of the substrate is not limited to the shape of this embodiment.
Since the optical system of the present invention uses a slit to form a linear beam of a certain size on the surface of the semiconductor film, the width of the large grain crystal region does not change even if the object to be irradiated changes.
For example, laser irradiation may be performed on a substrate in which an a-Si film is formed on a glass substrate having a base film, or laser is applied to a substrate in which a peeling layer, a base film, and an a-Si film are formed in this order on the substrate. Even when irradiated, a wide crystal grain region having a wide width can be produced.

[Examples for producing TFTs]
In this embodiment, a process of manufacturing a thin film transistor (TFT) using the laser annealing apparatus according to the present invention will be described with reference to FIGS.
First, as illustrated in FIG. 6A, a base film 701 is formed over a glass substrate 700 having an insulating surface.

As the substrate 700, for example, a glass substrate such as barium borosilicate glass or alumino borosilicate glass, a quartz substrate, a SUS substrate, or the like can be used.
In addition, plastics typified by PET, PES, and PEN, and substrates made of a synthetic resin having flexibility such as acrylic generally tend to have a lower heat resistant temperature than other substrates. Any material can be used as long as it can withstand the processing temperature.
The base film 701 is provided to prevent an alkali metal such as Na or an alkaline earth metal contained in the glass substrate 700 from diffusing into the semiconductor film and adversely affecting the characteristics of the semiconductor element.

Therefore, an insulating film such as silicon oxide, silicon nitride, or silicon nitride oxide that can suppress diffusion of alkali metal or alkaline earth metal into the semiconductor film is used.
In this embodiment, a silicon nitride oxide film is formed to a thickness of 10 to 400 nm by plasma CVD.
When using a substrate containing alkali metal or alkaline earth metal, such as a glass substrate or plastic substrate, it is effective to provide a base film from the viewpoint of preventing the diffusion of impurities. When the diffusion of impurities does not cause any problem, it is not necessarily provided.

Next, an amorphous semiconductor film 702 is formed over the base film, and the film thickness is set to 25 to 100 nm (preferably 30 to 60 nm).
As the amorphous semiconductor film, silicon or silicon germanium can be used, but silicon is used here.
When silicon germanium is used, the concentration of germanium is preferably about 0.01 to 4.5 atomic%.
Subsequently, as shown in FIG. 6B, crystallization is performed by irradiating the amorphous semiconductor film 702 with laser light using the laser annealing apparatus of the present invention.

In this embodiment, a 10 W second harmonic, TEM ₀₀ continuous oscillation Nd: YVO ₄ laser is used as the laser light.
Note that the first beam spot formed on the surface of the amorphous semiconductor film 702 by processing laser light using the slit 731 and the lens 732 is a rectangular shape having a short axis of 10 μm and a long axis of 500 μm.
The laser light scans on the surface of the amorphous semiconductor film 702 in the direction of the arrow illustrated in FIG.
Crystal grains continuously grown in the scanning direction are formed by the laser light irradiation.

As described above, by forming crystal grains that extend long in the scanning direction, it is possible to form the crystalline semiconductor film 703 having almost no crystal grain boundaries in at least the channel direction of the TFT.
Further, a portion where the energy density of the laser beam is low is blocked using the slit 731 and projected onto the irradiation surface using the lens 732, thereby irradiating the linear laser beam with uniform intensity without fringes due to light diffraction. be able to.
After that, as shown in FIG. 6C, the crystalline semiconductor film 703 is patterned to form island-shaped semiconductor films 704 to 707, and various islands represented by TFTs using the island-shaped semiconductor films 704 to 707 are formed. A semiconductor element is formed.

Further, a gate insulating film 708 is formed so as to cover the island-shaped semiconductor films 704 to 707.
For the gate insulating film 708, for example, silicon oxide, silicon nitride, silicon nitride oxide, or the like can be used.
As a film formation method at that time, a plasma CVD method, a sputtering method, or the like can be used. Here, an insulating film containing silicon is formed with a thickness of 30 nm to 200 nm by a sputtering method.

Next, although not shown, a conductive film is formed on the gate insulating film and patterned to form a gate electrode.
After that, an impurity imparting n-type or p-type conductivity is selectively added to the island-shaped semiconductor films 704 to 707 using a gate electrode or a resist pattern formed and patterned as a mask, and the source region, drain, Regions, LDD regions and the like are formed.
Through the above steps, N-channel TFTs 710 and 712 and P-channel TFTs 711 and 713 can be formed over the same substrate (FIG. 6D).

Subsequently, an insulating film 714 is formed as a protective film thereof.
The insulating film 714 is formed as a single layer or a stacked structure by using a plasma CVD method or a sputtering method, using an insulating film containing silicon with a thickness of 100 nm to 200 nm.
In this embodiment, a silicon oxynitride film having a thickness of 100 nm is formed by plasma CVD.
Thereafter, an organic insulating film 715 is formed over the insulating film 714.

As the organic insulating film 715, an organic insulating film such as polyimide, polyamide, BCB, or acrylic applied by the SOG method is used.
The insulating film 715 is preferably a film having excellent flatness because it has a strong meaning of relieving unevenness due to the TFT formed on the glass substrate 900 and flattening.
Further, the insulating film 714 and the organic insulating film 715 are patterned by photolithography to form contact holes that reach the impurity regions.

Next, a conductive film is formed using a conductive material, and the conductive film is patterned to form wirings 716 to 723.
After that, when an insulating film 724 is formed as a protective film, a semiconductor device as illustrated in FIG. 6D is completed.
Note that a method for manufacturing a semiconductor device using the laser annealing method of the present invention is not limited to the above-described TFT manufacturing process.

The present invention is characterized in that a crystalline semiconductor film obtained using a laser light irradiation method is used as an active layer of a TFT.
As a result, variations in mobility, threshold value, and on-current between elements can be suppressed.
Note that the laser light is not limited to the irradiation conditions shown in this embodiment.
Further, a crystallization step using a catalytic element may be provided before crystallization with laser light.

Nickel (Ni) is used as the catalyst element, but germanium (Ge), iron (Fe), palladium (Pd), tin (Sn), lead (Pb), cobalt (Co), Elements such as platinum (Pt), copper (Cu), and gold (Au) can be used.
When a crystallization process using a laser beam is performed after a crystallization process using a catalytic element, the crystals formed during the crystallization using the catalytic element remain without being melted by the laser beam irradiation. Crystallization proceeds as a crystal nucleus.

That is, the upper layer portion of the semiconductor film is melted by laser irradiation, but the lower layer portion is not melted.
As described above, crystals that remain undissolved in the lower layer portion of the semiconductor film become crystal nuclei, and crystallization proceeds from the lower layer portion to the upper layer portion of the semiconductor film.
Therefore, the crystallinity of the semiconductor film can be further increased as compared with the case of only the crystallization process using laser light, and the roughness of the surface of the semiconductor film after crystallization using laser light can be suppressed.

Accordingly, variations in characteristics of semiconductor elements formed later, typically TFTs, can be further suppressed, and off current can be suppressed.
Note that after adding a catalytic element and performing heat treatment to promote crystallization, crystallinity may be further increased by laser light irradiation, or the heat treatment step may be omitted.
Specifically, after adding the catalyst element, laser light may be irradiated instead of the heat treatment to improve crystallinity.

In this embodiment, an example in which the laser irradiation method of the present invention is used for crystallization of a semiconductor film is shown, but the semiconductor film may be used to activate an impurity element doped.
The method for manufacturing a semiconductor device using the present invention can also be used for a method for manufacturing an integrated circuit or a semiconductor display device.
For a transistor using a functional circuit such as a driver or a CPU, an LDD structure or a structure in which the LDD overlaps with a gate electrode is preferable, and the transistor is preferably miniaturized in order to increase the speed.
Since the transistors 710 to 713 completed in this embodiment have an LDD structure, they are preferably used for a driver circuit that requires high-speed operation.

By using the present invention, various electronic devices can be completed using the thin film transistor shown in FIG.
A specific example will be described with reference to FIG.
FIG. 7A illustrates a display device, which includes a housing 2001, a support base 2002, a display portion 2003, a speaker portion 2004, a video input terminal 2005, and the like.
This display device is manufactured by using a thin film transistor formed by the manufacturing method shown in FIG.
The display device includes a liquid crystal display device, a light emitting device, and the like, and specifically includes all information display devices such as a computer, a TV broadcast reception, and an advertisement display.

FIG. 7B illustrates a computer, which includes a housing 2200, a display portion 2201, a keyboard 2203, an external connection port 2204, a pointing mouse 2205, and the like.
By using the manufacturing method illustrated in FIGS. 6A and 6B, application to the display portion 2201 and other circuits is possible.
Furthermore, the present invention can also be applied to semiconductor devices such as a CPU and a memory inside the main body.
FIG. 7C includes a mobile phone of a mobile terminal, a housing 2301, a display portion 2302, and the like.
Since electronic devices such as PDAs and digital cameras such as the mobile phone are mobile terminals, the display screen is small.
Therefore, by forming a functional circuit such as a CPU using a fine transistor as shown in FIG. 6, the size and weight can be reduced.

Further, the thin film transistor manufactured in this embodiment can be used as an ID chip.
For example, by using the manufacturing method shown in FIG. 6, application as an integrated circuit or memory in an ID chip is possible.
When used as a memory, the distribution process of goods can be recorded.
Furthermore, by recording the process in the production stage of goods, it becomes easy for wholesalers, retailers, and consumers to grasp the production area, producer, date of manufacture, processing method, and the like.
As described above, the applicable range of the semiconductor device manufactured according to the present invention is so wide that the semiconductor device manufactured according to the present invention can be applied to electronic devices in various fields.

1 is a bird's eye view showing a laser annealing method and apparatus for explaining the best mode for carrying out the invention and Example 1. FIG. 1A and 1B are a top view and a side view showing a laser annealing method and apparatus for explaining the best mode for carrying out the invention and Example 1. FIG. FIG. 6 is a bird's-eye view showing a laser annealing method and apparatus for explaining the second embodiment. The bird's-eye view which shows the laser annealing method and apparatus for demonstrating Example 3 which is a 2nd laser annealing method and apparatus. The top view and side view which show the laser annealing method and apparatus for demonstrating Example 3 which is a 2nd laser annealing method and apparatus. A process of manufacturing a thin film transistor (TFT) using a laser annealing apparatus according to the present invention is illustrated. Various display devices that can be manufactured by the laser annealing method of the present invention. The semiconductor film surface crystallized by the laser annealing method of the present invention. A semiconductor film surface crystallized by a conventional laser annealing method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Laser oscillator 102 Slit 103 Mirror 104 Cylindrical lens 105 Cylindrical lens 106 Semiconductor film 107 Glass substrate 108 X stage 109 Y stage

Claims (12)

The laser light emitted from the laser oscillator is passed through the slit to cut off the low energy density part, and the image formed in the slit on the laser light passing line is projected onto the irradiation surface by the convex cylindrical lens or convex spherical lens. And a laser annealing method for irradiating the irradiation surface with a linear beam. The laser light emitted from the laser oscillator is passed through the slit to cut off the low energy density part, and the image formed in the slit on the laser light passing line is projected onto the irradiation surface by the convex cylindrical lens or convex spherical lens. And an interval between the slit and the convex cylindrical lens or convex spherical lens (M1) and an interval between the convex cylindrical lens or convex spherical lens and the irradiation surface (M2) Is a laser annealing method for irradiating a linear beam on an irradiation surface, which is arranged so as to satisfy the relationship of the following formulas (1) and (2):
M1 = f (s + D) / D Formula (1)
M2 = f (s + D) / s Formula (2)
(Where, s is the width of the slit, D is the length of the long side direction of the linear beam, and f is the focal length of the convex cylindrical lens or convex spherical lens.) The laser annealing method according to claim 1, wherein a mirror that deflects a traveling direction of the laser beam by a predetermined angle is disposed between the laser oscillator and the slit. 4. The laser annealing according to claim 1, wherein a second convex cylindrical lens is disposed between the convex cylindrical lens and the irradiation surface in a direction in which the convex surface is shifted by 90 degrees with respect to the convex cylindrical lens. Method. A laser oscillator, a slit that allows the laser light emitted from the oscillator to pass therethrough and cuts off a portion having a low energy density, and an image formed on the slit on the passage line of the laser light that has been cut off from the low portion is projected onto the irradiation surface A laser annealing apparatus for irradiating a linear beam on an irradiation surface, comprising a convex cylindrical lens or a convex spherical lens. A laser oscillator, a slit that allows the laser light emitted from the oscillator to pass therethrough and cuts off a portion having a low energy density, and an image formed on the slit on the passage line of the laser light that has been cut off from the low portion is projected onto an irradiation surface. A convex cylindrical lens or convex spherical lens is provided, and an interval (M1) between the slit and the convex cylindrical lens or convex spherical lens and an interval between the convex cylindrical lens or convex spherical lens and the irradiation surface A laser annealing apparatus for irradiating a linear beam on an irradiation surface, wherein (M2) is arranged so that the relationship of the following formulas (1) and (2) is satisfied.
M1 = f (s + D) / D Formula (1)
M2 = f (s + D) / s Formula (2)
(In the above equation, s is the width of the slit, D is the length of the long side direction of the linear beam, and f is the focal length of the convex cylindrical lens or convex spherical lens.) The laser annealing apparatus according to claim 5 or 6, wherein a mirror for deflecting a traveling direction of the laser beam by a predetermined angle is disposed between the laser oscillator and the slit. The laser annealing according to claim 5, 6 or 7, wherein a second convex cylindrical lens is disposed between the convex cylindrical lens and the irradiation surface in a direction in which the convex surface is shifted by 90 degrees with respect to the convex cylindrical lens. apparatus. The laser beam emitted from the laser oscillator is incident from a direction inclined by a predetermined angle by a mirror, passes through the first convex spherical lens, forms a linear laser beam by astigmatism, and then forms a linear laser beam by a slit. On the irradiation surface, the portion having a low energy density of the laser beam is cut off, and the irradiation surface arranged at a position where the image of the linear laser beam in the slit can be projected using the second convex spherical lens Laser annealing method for irradiating a linear beam on the surface. The laser beam emitted from the laser oscillator is incident from a direction inclined by a predetermined angle by a mirror, passes through the first convex spherical lens, forms a linear laser beam by astigmatism, and then forms a linear laser beam by a slit. A portion having a low energy density of the laser beam is cut off, and an image of the linear laser beam in the slit is irradiated onto an irradiation surface arranged at a position where the image can be projected using the second convex spherical lens, and the slit The distance (M1) between the second convex spherical lens and the second convex spherical lens and the distance (M2) between the second convex spherical lens and the irradiation surface satisfy the following expressions (1) and (2). A laser annealing method for irradiating a linear beam on an irradiation surface characterized by arranging them as described above.
M1 = f (s + D) / D Formula (1)
M2 = f (s + D) / s Formula (2)
(Where, s is the width of the slit, D is the length of the long side direction of the linear beam, and f is the focal length of the second convex spherical lens.) A laser oscillator, a mirror inclined at a predetermined angle for guiding laser light emitted from the oscillator to a convex spherical lens, and a laser beam reflected by the mirror to pass therethrough to form linear laser light by astigmatism A convex spherical lens, a slit that blocks a low energy density portion of the linear laser light, and a second convex spherical lens that projects an image of the linear laser light in the slit onto the irradiation surface. A laser annealing apparatus that irradiates a linear beam onto the irradiation surface. A laser oscillator, a mirror inclined at a predetermined angle for guiding laser light emitted from the oscillator to a convex spherical lens, and a laser beam reflected by the mirror to pass therethrough to form linear laser light by astigmatism A convex spherical lens, a slit that blocks a low energy density portion of the linear laser light, and a second convex spherical lens that projects an image of the linear laser light in the slit onto the irradiation surface, and the slit The distance (M1) between the second convex spherical lens and the second convex spherical lens and the distance (M2) between the second convex spherical lens and the irradiation surface satisfy the following expressions (1) and (2). A laser annealing apparatus for irradiating a linear beam on an irradiation surface, characterized in that they are arranged as described above.
M1 = f (s + D) / D Formula (1)
M2 = f (s + D) / s Formula (2)
(Where, s is the width of the slit, D is the length of the long side direction of the linear beam, and f is the focal length of the second convex spherical lens.)

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