JP3883936B2 - Laser irradiation method and semiconductor device manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for irradiating a laser beam (laser beam) and a laser irradiation apparatus for performing the method (an apparatus including a laser and an optical system for guiding a laser beam (laser beam) output from the laser to an irradiation object) About. Further, the present invention relates to a method for manufacturing a semiconductor device manufactured by including laser beam (laser beam) irradiation in a process. Note that the semiconductor device here includes an electro-optical device such as a liquid crystal display device and a light-emitting device and an electronic device including the electro-optical device as a component.
[0002]
[Prior art]
In recent years, a technique for performing laser annealing on a semiconductor film formed on an insulating substrate such as glass to crystallize, improving crystallinity to obtain a crystalline semiconductor film, or activating an impurity element has been developed. Has been extensively studied. Note that in this specification, a crystalline semiconductor film refers to a semiconductor film in which a crystallized region exists, and includes a semiconductor film in which the entire surface is crystallized.
[0003]
A pulse laser beam (laser beam) such as an excimer laser is shaped by an optical system so as to form a square spot of several centimeters square or a linear shape with a length of 100 mm or more on the surface to be irradiated. The method of performing annealing by moving (or moving the irradiation position of the laser beam (laser beam) relative to the irradiated surface) is highly productive and industrially excellent. In addition, “linear” here does not mean “line” in a strict sense, but means a rectangle (or oval) having a large aspect ratio. For example, the aspect ratio is 10 or more (preferably 100 to 10,000). The linear shape is used to ensure sufficient energy density for annealing the irradiated object, and sufficient annealing can be performed on the irradiated object even in a rectangular or planar shape. If it is. Currently, a 15 J / pulse excimer laser is commercially available, and in the future, laser annealing may be performed using a planar laser beam (laser beam).
[0004]
FIG. 7 shows an example of the configuration of an optical system for making the shape of laser light (laser beam) linear on the surface to be irradiated. This configuration is very general, and all the optical systems conform to the configuration shown in FIG. This configuration not only converts the cross-sectional shape of the laser beam (laser beam) into a linear shape, but also at the same time makes the energy density distribution of the laser beam (laser beam) uniform on the irradiated surface. In general, an optical system that makes the energy density distribution of laser light (laser beam) uniform is called a beam homogenizer.
[0005]
A laser beam (laser beam) emitted from the laser 101 is divided by a cylindrical lens group (hereinafter, referred to as a cylindrical lens array) 103 in a direction perpendicular to the traveling direction of the laser beam (laser beam), so that a linear laser beam is obtained. The length of the light (laser beam) in the longitudinal direction is determined. This direction will be referred to as the first direction in this specification. The first direction is bent according to the direction of light bent by the mirror when the mirror is inserted in the middle of the optical system. In the configuration of the top view of FIG. Thereafter, the laser beam (laser beam) is synthesized on the irradiated surface 109 by the cylindrical lens 105, and the energy density distribution in the longitudinal direction of the linear laser beam (laser beam) is made uniform.
[0006]
Next, the side view of FIG. 7 will be described. The laser beam (laser beam) emitted from the laser 101 is divided by the cylindrical lens arrays 102a and 102b in a direction perpendicular to the traveling direction of the laser beam (laser beam) and the first direction, so that a linear laser beam (laser beam) is obtained. The length in the short direction of the beam is determined. The direction is referred to as a second direction in this specification. The second direction is bent according to the direction of light bent by the mirror when a mirror is inserted in the middle of the optical system. The cylindrical lens arrays 102a and 102b in the side view of FIG. 7 are each divided into four. These divided laser beams (laser beams) are once combined by the cylindrical lens 104. Thereafter, the laser beam (laser beam) is reflected by the mirror 107, and then condensed again into one laser beam (laser beam) by the doublet cylindrical lens 108 on the irradiated surface 109. A doublet cylindrical lens refers to a lens composed of two cylindrical lenses. Thus, the energy density distribution in the short direction of the linear laser beam (laser beam) is made uniform.
[0007]
For example, if an excimer laser having a size of 10 mm × 30 mm (both half-value width in the beam profile) is used as the laser 101 and is molded by the optical system having the configuration shown in FIG. A linear laser beam (laser beam) having a uniform distribution of 125 mm × 0.4 mm can be obtained.
[0008]
At this time, a high transmittance is obtained when the base material of the optical system is, for example, quartz. The optical system may be coated so that a transmittance of 99% or more is obtained with respect to the wavelength of the excimer laser to be used.
[0009]
Then, the entire surface of the amorphous semiconductor is irradiated with the linear laser beam (laser beam) formed in the above-described configuration while being gradually shifted in the short direction of the laser beam (laser beam). Laser annealing can be performed to crystallize the amorphous semiconductor, improve the crystallinity to obtain a crystalline semiconductor film, or activate the impurity element.
[0010]
In addition, the area of a substrate used for manufacturing a semiconductor device is increasing. This is because, for example, TFTs for a pixel portion and a drive circuit (a source driver portion and a gate driver portion) are manufactured on a single glass substrate to manufacture a semiconductor device such as a single liquid crystal display panel. This is because when a single large-area substrate is used to manufacture a plurality of semiconductor devices such as a panel for a liquid crystal display device, throughput is high and cost can be reduced. (FIG. 9). At present, as a large-area substrate, for example, a 600 mm × 720 mm substrate, a circular 12-inch (diameter of about 300 mm) substrate, and the like are used. Furthermore, it is predicted that a substrate having a side exceeding 1000 mm will be used in the future.
[0011]
[Problems to be solved by the invention]
The energy density of the end portions of linear, rectangular, and planar laser beams (laser beams) formed on or near the irradiated surface by the optical system is gradually attenuated due to lens aberrations and the like. (FIG. 8A) In this specification, a region where the energy density gradually attenuates at the end of a linear, rectangular, or planar laser beam (laser beam) is called an attenuation region.
[0012]
In addition, with increasing substrate area and laser output, longer linear laser beams (laser beams), rectangular laser beams (laser beams), and larger planar laser beams (laser beams) Is being formed. This is because it is more efficient to perform annealing with such a laser beam (laser beam). However, since the energy density at the end of the laser beam (laser beam) oscillated from the laser is lower than that near the center, when the laser beam (laser beam) is further expanded by the optical system, the attenuation region is reduced. There is a tendency to become more prominent.
[0013]
The attenuation region of the laser beam (laser beam) is not sufficiently high in energy density as compared with the region having high energy density uniformity, and is gradually attenuated. For this reason, even if annealing is performed using laser light (laser beam) having the attenuation region, uniform annealing cannot be performed on the irradiated object. (FIG. 8 (B)). In addition, even if annealing is performed by a method in which the laser beam (laser beam) attenuation region is overlapped and scanned, the annealing condition is clearly different from that of the region with high energy density uniformity. It cannot be annealed uniformly. As described above, the region annealed by the attenuation region of the laser beam (laser beam) and the region annealed by the region having high energy density uniformity of the laser beam (laser beam) cannot be treated equally.
[0014]
For example, when the irradiated object is a semiconductor film, a region annealed by a laser beam (laser beam) attenuation region and a region annealed by a region where the energy density of the laser beam (laser beam) is high Then, the crystallinity is different. Therefore, even when a TFT is manufactured using such a semiconductor film, the electrical characteristics of the TFT manufactured in the region annealed by the attenuation region of the laser beam (laser beam) are reduced, and the variation of TFTs in the same substrate is reduced. It becomes a factor. Actually, TFTs are manufactured using a region annealed by such an attenuation region of laser light (laser beam), and a semiconductor device is rarely manufactured. The number of TFTs that can be used per substrate. Decreases, which causes a decrease in throughput.
[0015]
Therefore, an object of the present invention is to provide a laser irradiation apparatus that can efficiently perform annealing by removing an attenuation region at an end of a laser beam (laser beam). It is another object of the present invention to provide a laser irradiation method using such a laser irradiation apparatus and to provide a method for manufacturing a semiconductor device including the laser irradiation method in a process.
[0016]
[Means for Solving the Problems]
In the present invention, as shown in FIG. 1A, a slit is used in the very vicinity of the irradiated surface to attenuate the attenuation region of the laser beam (laser beam), at least the portion parallel to the moving direction of the laser beam (laser beam). The region is removed or reduced, and the energy density distribution at the end of the laser beam (laser beam) is made steep as shown in FIG. Note that an attenuation region in a portion parallel to the moving direction of the laser beam (laser beam) and an attenuation region in a portion perpendicular to the moving direction of the laser beam (laser beam) may be removed or reduced. The reason why it is installed very close to the surface to be irradiated is to suppress the spread of the laser beam (laser beam). For this reason, the slit is brought close to the substrate (typically within 1 cm) within the range allowed by the apparatus. Moreover, you may install in contact with a to-be-irradiated surface. Furthermore, the present invention uses a mirror as shown in FIG. 1B to fold back the attenuation region of the laser light (laser beam) and strengthen the attenuation region, and reduce the attenuation region to reduce the laser beam (laser beam). The distribution of energy density at the end of () is made steep.
[0017]
If the attenuation region of the end of the laser beam (laser beam), at least the portion parallel to the moving direction of the laser beam (laser beam) is steep, the laser beam (laser beam) has high energy density uniformity. Therefore, uniform annealing can be performed on the irradiated object, and the annealing can be efficiently performed. Note that an attenuation region in a portion parallel to the moving direction of the laser beam (laser beam) and an attenuation region in a portion perpendicular to the moving direction of the laser beam (laser beam) may be removed or reduced. (FIG. 2 (B)).
[0018]
The structure of the invention relating to the laser irradiation apparatus disclosed in this specification is the distribution of the first energy density on the irradiated surface of the laser and the laser beam (laser beam) emitted from the laser. A first means for distribution, and a second means for uniformizing the energy density at the end of the laser beam (laser beam) having the second energy density distribution, wherein the second means comprises: It is characterized by being provided between the irradiated surface and the first means.
[0019]
Further, in the structure of the invention relating to the laser irradiation apparatus disclosed in this specification, the cross-sectional shape of the laser and the laser beam (laser beam) emitted from the laser is deformed to the first shape, and the irradiated surface is irradiated. 1st means, and 2nd means to make the energy density of the edge part of the laser beam (laser beam) deform | transformed into the said 1st shape uniform, The said 2nd means is the said optical system, It is provided between the irradiated surface.
[0020]
Further, in the structure of the invention relating to the laser irradiation method disclosed in this specification, the distribution of the first energy density on the irradiated surface of the laser light (laser beam) emitted from the laser is changed to the second by the first means. A laser beam (laser beam) having a uniform energy density at the end of the laser beam (laser beam) having the second energy density distribution is applied to the irradiated surface by the second means. It is characterized by irradiating while relatively moving.
[0021]
In addition, in the configuration of the invention relating to the laser irradiation method disclosed in this specification, the cross-sectional shape of the laser light (laser beam) emitted from the laser is transformed into the first shape by the first means, and the irradiated surface is formed. The laser beam (laser beam) that is irradiated and is made uniform in the energy density at the end of the laser beam (laser beam) transformed into the first shape by the second means is relative to the irradiated surface. It is characterized by irradiating while moving.
[0022]
In addition, in the structure of the invention relating to the method for manufacturing a semiconductor device disclosed in this specification, the first energy density distribution on the irradiated surface of the laser light (laser beam) emitted from the laser is changed by the first means. The laser beam (laser beam) having a uniform energy density at the end of the laser beam (laser beam) having the second energy density distribution is irradiated by the second means. It is characterized by irradiating while moving relative to the surface.
[0023]
Further, in the structure of the invention relating to the method for manufacturing a semiconductor device disclosed in this specification, the cross-sectional shape of the laser light (laser beam) emitted from the laser is transformed into the first shape by the first means and irradiated. A laser beam (laser beam) having a uniform energy density at the end of the laser beam (laser beam) transformed into the first shape by the second means is irradiated onto the surface to be irradiated. It is characterized by irradiating while moving relatively.
[0024]
In the above configuration, the first means is a homogenizer disposed so as to be orthogonal to the optical axis of the laser beam (laser beam).
[0025]
In the above configuration, the first means is arranged in parallel so as to be orthogonal to the optical axis of the laser beam (laser beam), and a plurality of cylindrical beams that divide the laser beam (laser beam) in the arrangement direction. It is a lens group.
[0026]
In the above configuration, the first means is arranged in parallel so as to be orthogonal to the optical axis of the laser beam (laser beam), and a plurality of cylindrical beams that divide the laser beam (laser beam) in the arrangement direction. The lens group and a lens arranged on the transmission side of the cylindrical lens group for synthesizing the divided laser beams (laser beams).
[0027]
Further, in the above configuration, the first means is a fly-eye lens that is arranged so as to be orthogonal to the optical axis of the laser beam (laser beam) and divides the laser beam (laser beam). Yes.
[0028]
Further, in the above configuration, the first means is disposed so as to be orthogonal to the optical axis of the laser beam (laser beam), and a fly-eye lens that divides the laser beam (laser beam); The spherical lens is arranged on the transmission side of the lens and synthesizes the divided laser beams (laser beams).
[0029]
Further, in the above configuration, the second means is a slit disposed near the irradiated surface or a mirror installed at an end of a laser beam (laser beam) having the second energy density distribution. It is characterized by being.
[0030]
In the above configuration, the end of the laser beam (laser beam) is a region parallel to the moving direction of the laser beam (laser beam).
[0031]
In the above configuration, the laser beam (laser beam) may be converted into a harmonic by a non-linear optical element. For example, a YAG laser is known to emit a laser beam (laser beam) having a wavelength of 1065 nm as a fundamental wave. The absorption coefficient of this laser beam (laser beam) with respect to the silicon film is very low, and it is technically difficult to crystallize an amorphous silicon film which is one of the semiconductor films. However, this laser beam (laser beam) can be converted to a shorter wavelength by using a nonlinear optical element, and the second harmonic (532 nm), the third harmonic (355 nm), the fourth harmonic can be used as the harmonic. A harmonic (266 nm) and a fifth harmonic (213 nm) are exemplified. Since these harmonics have a higher absorption coefficient than the amorphous silicon film, they can be used for crystallization of the amorphous silicon film.
[0032]
In the above structure, the laser is a continuous wave or pulsed solid laser or gas laser. The solid-state laser may be a continuous wave or pulsed YAG laser, YVO _Four Laser, YLF laser, YAlO _Three There are a laser, a glass laser, a ruby laser, an alexandride laser, a Ti: sapphire laser, and the gas laser includes a continuous wave or pulsed excimer laser, an Ar laser, a Kr laser, and the like.
[0033]
In the above configuration, the laser beam (laser beam) may be converted into a harmonic by a nonlinear optical element.
[0034]
In the above structure, the laser is a continuous wave or pulsed solid laser or gas laser. The solid-state laser may be a continuous wave or pulsed YAG laser, YVO _Four Laser, YLF laser, YAlO _Three There are a laser, a glass laser, a ruby laser, an alexandride laser, a Ti: sapphire laser, and the gas laser includes a continuous wave or pulsed excimer laser, an Ar laser, a Kr laser, and the like.
[0035]
By installing a slit in the vicinity of the irradiated surface or on the irradiated surface, or by installing a mirror in the laser light (laser beam) attenuation region, typically near the middle of the attenuation region, The energy density distribution of the laser beam (laser beam) in the vicinity can be made excellent in uniformity, and the irradiated object can be annealed uniformly.
Conventionally, the divided laser light (laser beam) is synthesized by the cylindrical lens 105 of FIG. 7 and the attenuation region is reduced. However, according to the present invention, the laser can be obtained without providing the cylindrical lens 105 in the optical system. The energy density distribution at the end of the light (laser beam) can be made steep. This reduces the number of lenses used in the optical system, facilitates optical adjustment, and allows uniform annealing. Note that when the cylindrical lens 105 is used, an attenuation region of the laser beam (laser beam) can be reduced, so that a slit or laser beam (laser beam (close to the irradiated surface or in contact with the irradiated surface) Since the area of the laser beam (laser beam) applied to the mirror installed near the middle of the attenuation region of the laser beam can be suppressed, there is an effect that a smaller mirror or slit can be used. .
Uniform annealing is very important to make the properties of the irradiated object uniform. The present invention is particularly effective when annealing a large area substrate. For example, when the irradiated object is annealed by irradiating a laser beam (laser beam) shorter than the length of the large area substrate, it is necessary to anneal the large area substrate by performing a plurality of scans relatively. However, the laser beam (laser beam) formed according to the present invention is a laser beam (laser beam) having an extremely excellent energy distribution particularly in a portion parallel to the moving direction of the laser beam (laser beam). Uniform annealing can also be performed at locations where the scanned regions of (laser beam) are adjacent. This eliminates variations in annealing in any part of the large-area substrate, so that the large-area substrate can be used without waste and throughput can be improved. For example, if a semiconductor film is formed on the large-area substrate, the film quality of the uniformly annealed semiconductor film becomes uniform, and the electrical characteristics of a TFT fabricated using such a semiconductor film It is possible to reduce variation in characteristics. In addition, the operating characteristics and reliability of a semiconductor device manufactured from such a TFT can be improved.
[0036]
DETAILED DESCRIPTION OF THE INVENTION
In the present embodiment, a method for removing the attenuation region by the slit will be described with reference to FIG. FIG. 3A shows an optical system viewed from the vertical direction in the vertical direction, and FIG. 3B shows an optical system viewed from the vertical direction in the short direction.
[0037]
Laser light emitted from the laser 1101 is magnified approximately twice in both the long and short directions by a beam expander. The beam expander is particularly effective when the shape of the laser beam (laser beam) emitted from the laser is small, and may not be used depending on the size of the laser beam (laser beam).
[0038]
Laser light (laser beam) emitted from the beam expander is incident on cylindrical lens arrays 1103a and 1103b and a cylindrical lens 1104 which are first forming means. These three lenses are arranged so that the curvature of the laser beam (laser beam) is parallel to the longitudinal direction, and the laser beam (laser beam) has a uniform energy density distribution in the longitudinal direction.
[0039]
A laser beam (laser beam) emitted from the cylindrical lens 1104 is a third lens forming a cylindrical lens array 1105a, a cylindrical lens array 1105b, a cylindrical lens 1106, and two cylindrical lenses 1107a and 1107b. Incident on 1107. These lenses are arranged so that the curvature is parallel to the short direction of the laser beam (laser beam), and the laser beam (laser beam) has a uniform energy density distribution in the short direction and simultaneously has a reduced width. .
[0040]
Then, a slit 1108 which is the second forming means is arranged very close to the irradiated surface, the attenuation region in the laser beam (laser beam) is shielded by the slit 1108, and the laser beam (laser beam) is attenuated on the irradiated surface 1109. The width and position of the slit 1108 are set so that the region does not reach. Typically, it is preferable to install in the very vicinity of the irradiated surface. This is to suppress the spread of the laser beam (laser beam). For this reason, the slit is brought close to the substrate (typically within 1 cm) within the range allowed by the apparatus. Moreover, you may install in contact with a to-be-irradiated surface. Thereby, a linear laser beam (laser beam) having a sharp energy density distribution at the end of the laser beam (laser beam) can be obtained.
[0041]
By annealing a semiconductor film using such a laser irradiation apparatus, the semiconductor film can be crystallized, a crystalline semiconductor film can be obtained by improving crystallinity, or an impurity element can be activated. .
[0042]
Moreover, in this embodiment, although the slit is used, not only this but a mirror can also be used. In the case of using a mirror, an attenuation region of the laser beam (laser beam), at least an attenuation region in a portion parallel to the moving direction of the laser beam (laser beam), typically a mirror near the middle of the width of the attenuation region. When installed, the laser beam (laser beam) is reflected near the center of the attenuation region. Since the energy density of the attenuation region is synthesized between the non-reflected portion and the reflected portion, the energy density can be made equal to that of the region having a uniform energy density distribution. Note that a mirror may be provided in the vicinity of the center of the attenuation region in a portion parallel to the moving direction of the laser beam (laser beam) and the attenuation region in a portion perpendicular to the moving direction of the laser beam (laser beam). Typically, when a mirror is installed in the vicinity of the middle of the width of the attenuation region, the energy density can be made equal to that of a region having a uniform energy density distribution.
[0043]
Various lasers can be applied to the present invention by changing the coating applied to the surface of the synthetic quartz glass to an appropriate one depending on the wavelength of the laser used.
[0044]
In the present embodiment, laser light (laser beam) having a linear shape on the irradiated surface is formed, but the present invention is not limited to a linear shape. Further, since it differs depending on the type of laser emitted from the laser, even if it is molded by an optical system, it is easily affected by the original shape. For example, the shape of laser light (laser beam) emitted from a XeCl excimer laser (wavelength 308 nm, pulse width 30 ns) is a rectangular shape of 10 mm × 30 mm (both half-value width in the beam profile), and laser emitted from a solid-state laser The shape of the light (laser beam) is circular if the rod shape is cylindrical, and rectangular if it is a slab type. In any shape, there is no problem as long as the energy density is sufficient for annealing the irradiated object, and the present invention can be applied.
[0045]
The present invention configured as described above will be described in more detail with reference to the following examples.
[0046]
【Example】
[Example 1]
In this embodiment, a method for making the end of a linear laser beam (laser beam) sharp using a slit will be described with reference to FIG. FIG. 3A shows an optical system viewed from the vertical direction of the laser beam (laser beam), and FIG. 3B shows an optical system viewed from the vertical direction of the laser beam (laser beam).
[0047]
In the present specification, in the description of the lens arrangement, the traveling direction of laser light (laser beam) is assumed to be the front. The lens has a laser beam (laser beam) incident side as a first surface and an emission side as a second surface, and the radius of curvature of the first surface is R. ₁ , The radius of curvature of the second surface is R ₂ Represented by The sign of the radius of curvature to be used is negative when the center of curvature is on the incident side of the laser beam (laser beam) as viewed from the lens, positive when it is on the emission side, and ∞ when it is a plane. Further, all the lenses used are made of synthetic quartz glass (refractive index: 1.485634), but are not limited thereto.
[0048]
A laser beam (laser beam) emitted from the laser 1101 is a beam expander (radius 50 mm, thickness 7 mm, R ₁ = -220mm, R ₂ = 50 mm radius from the spherical lenses 1102a and 1102a of 1102a, a thickness of 7 mm, R ₁ = ∞, R ₂ = -400 mm spherical lens 1102b) is magnified approximately twice in the long and short directions.
[0049]
Laser light (laser beam) emitted from the beam expander is incident on a cylindrical lens array 1103a disposed 50 mm ahead of the beam expander 1102b, then passes through the cylindrical lens array 1103b 88mm ahead of the cylindrical lens array 1103a, and is further cylindrical. The light enters the cylindrical lens 1104 disposed 120 mm in front of the lens array 1103b. The cylindrical lens array 1103a has a length of 60 mm, a width of 2 mm, a thickness of 5 mm, R ₁ = 28mm, R ₂ == 40 cylindrical lenses in an array. The cylindrical lens array 1103b has a length of 60 mm, a width of 2 mm, a thickness of 5 mm, R ₁ = -13.33 mm, R ₂ == 40 cylindrical lenses in an array. The cylindrical lens 1104 has a length of 150 mm, a width of 60 mm, a thickness of 20 mm, R ₁ = 2140mm, R ₂ = Cylindrical lens with ∞. The cylindrical lens arrays 1103a and 1103b and the cylindrical lens 1104 are both arranged so that the curvature is parallel to the longitudinal direction. The light beams are divided by the cylindrical lens arrays 1103a and 1103b, and the light beams divided by the cylindrical lenses 1104 are overlapped to make the energy density distribution uniform. With these three lenses, the laser beam (laser beam) has a uniform energy density distribution in the longitudinal direction.
[0050]
The laser light (laser beam) emitted from the cylindrical lens 1104 enters the cylindrical lens array 1105a that is 395 mm in front of the cylindrical lens 1104, passes through the cylindrical lens array 1105b that is 65 mm in front, and further 1600 mm in front of the cylindrical lens array 1105b. The light enters the cylindrical lens 1106. The cylindrical lens array 1105a has a length of 150 mm, a width of 2 mm, a thickness of 5 mm, R ₁ = 100mm, R ₂ This is an array of 16 cylindrical lenses with ∞. The cylindrical lens array 1105b has a length of 150 mm, a width of 2 mm, a thickness of 5 mm, R ₁ = ∞, R ₂ = 16 cylindrical lenses of 80 mm are arranged in an array. The cylindrical lens 1106 has a length of 900 mm, a width of 60 mm, a thickness of 20 mm, R ₁ = ∞, R ₂ = -486 mm cylindrical lens. The cylindrical lens arrays 1105a and 1105b and the cylindrical lens 1106 are all arranged so that their curvatures are parallel to the short direction. With these three lenses, the laser beam (laser beam) has a uniform energy density distribution in the short direction and at the same time the width is reduced, and a linear laser beam (laser beam) having a width of 2 mm is formed 800 mm in front of the cylindrical lens 1106. ) Is made.
[0051]
In order to further reduce the above-described linear laser beam (laser beam) having a width of 2 mm, a doublet cylindrical lens 1107 is arranged 2050 mm ahead of the cylindrical lens 1106. The doublet cylindrical lens 1107 includes two cylindrical lenses 1107a and 1107b. The cylindrical lens 1107a is 400 mm long, 70 mm wide, 10 mm thick, R ₁ = 125mm, R ₂ = 77 mm cylindrical lens. The cylindrical lens 1107b is 400 mm long, 70 mm wide, 10 mm thick, R ₁ = 97mm, R ₂ = -200 mm cylindrical lens. Further, the cylindrical lenses 1107a and 1107b are provided with an interval of 5.5 mm. Both cylindrical lenses 1107a and 1107b are arranged so that the curvature is parallel to the short direction.
[0052]
A linear laser beam (laser beam) having a length of 300 mm and a width of 0.4 mm is generated on a flat surface 1109 of 237.7 mm in front of the doublet cylindrical lens 1107. The linear laser beam (laser beam) formed at this time has a distribution of energy density in such a shape that the end in the longitudinal direction gradually attenuates. In order to remove this energy attenuation region, a slit 1108 is disposed very close to the irradiated surface. The light beam corresponding to the energy attenuation region is shielded by the slit 1108, and the width and position of the slit 1108 are set so that the light beam does not reach the irradiated surface 1109. Thereby, a linear laser beam (laser beam) having a sharp energy distribution at the end can be obtained. In this example, a slit was installed at a position 2 mm away from the substrate.
[0053]
19 may be used instead of the three lenses of the cylindrical lens arrays 1103a and 1103b and the cylindrical lens 1104, or the three lenses of the cylindrical lens arrays 1105a and 1105b and the cylindrical lens 1106. Even if this homogenizer is used, the laser beam (laser beam) at or near the irradiated surface has an attenuation region at the end. Therefore, a slit is provided to remove the attenuation region, and the energy distribution is a steep line. Laser beam (laser beam) is formed.
[0054]
If such a laser irradiation apparatus is used, uniform annealing can be performed on the irradiated object. For example, if annealing is performed using a semiconductor film as an irradiation object, the semiconductor film is crystallized, a semiconductor film having uniform crystallinity is obtained by improving crystallinity, or an impurity element is activated. It can be carried out.
[0055]
[Example 2]
In this embodiment, a method of using a mirror to sharpen the end of linear laser light (laser beam) will be described.
[0056]
A linear laser beam (laser beam) is shaped using the optical system shown in the first embodiment. However, as shown in FIG. 1 (B), the side surface of the slit is a mirror, and is arranged in the vicinity of the center of the energy attenuation region. The light beam in the energy attenuation region is turned back by the mirror and irradiated to the remaining energy attenuation region. As a result, the attenuation region is reduced, and a linear laser beam (laser beam) having a sharp energy distribution at the end of the laser beam (laser beam) is formed on the irradiated surface.
[0057]
If such a laser irradiation apparatus is used, uniform annealing can be performed on the irradiated object. For example, if annealing is performed using a semiconductor film as an object to be irradiated, the semiconductor film is crystallized, a crystalline semiconductor film having uniform crystallinity is obtained by improving crystallinity, and the activity of impurity elements is increased. Can be made.
[0058]
[Example 3]
In this embodiment, a method of making the end of a planar laser beam (laser beam) steep will be described with reference to FIGS.
[0059]
Laser light (laser beam) emitted from the laser 1101 enters the fly-eye lens 1302. Note that a cylindrical lens may be inserted as a beam expander between the oscillation device and the fly-eye lens in order to set the aspect ratio of incident laser light (laser beam) to 1: 1. Fly eye lens 1302 is R ₁ = 10mm, R ₂ = ∞, 5 mm thick, 1 mm square spherical lenses are arranged as shown in FIG. 5a. Note that the array is optimally arranged for uniform energy distribution according to the shape of the incident laser light (laser beam) (example of arrangement: FIG. 5b). Further, in order to make the array similar to the semiconductor film to be laser-annealed, it is also possible to consider shapes such as FIG. 5c (rectangle), d (parallelogram), e (diamond), and f (regular hexagon). It is done. A spherical lens 1303 is disposed 20 mm in front of the fly-eye lens 1302. The spherical lens 1303 is R ₁ = 300mm, R ₂ = ∞, thickness 20 mm, 150 mm square.
[0060]
Light beams divided by the fly-eye lens 1302 are superimposed by a spherical lens 1303, and a 30 mm × 30 mm planar laser beam (laser beam) in which the energy distribution is made uniform on the irradiated surface 1305 600 mm ahead of the fly-eye lens 1302. ) Is formed. Since the edge energy of the planar laser beam (laser beam) formed at this time is attenuated, a slit 1304 is provided very close to the irradiated surface in order to remove it. A view of the slit 1304 viewed from the light incident side is shown in FIG. The light beam corresponding to the energy attenuation region is shielded, and the width and position of the slit 1304 are set so that the light beam does not reach the irradiated surface 1305. A square planar laser beam (laser beam) having a sharp energy distribution at the end of the laser beam (laser beam) is formed on the irradiated surface 1305. In this example, a slit was installed at a position 2 mm away from the substrate. Note that even if the slit is replaced with a mirror, a linear laser beam (laser beam) or a planar laser beam (laser beam) can be formed in the same manner.
[0061]
If such a laser irradiation apparatus is used, uniform annealing can be performed on the irradiated object. For example, if annealing is performed using a semiconductor film as an object to be irradiated, the semiconductor film is crystallized, a crystalline semiconductor film having uniform crystallinity is obtained by improving crystallinity, and the activity of impurity elements is increased. Can be made.
[0062]
[Example 4]
In this embodiment, the case where laser annealing is performed on a large-area substrate will be described with reference to FIG.
[0063]
First, according to any one of the first to third embodiments, a laser beam (laser beam) with high energy density uniformity is formed. Then, the laser beam (laser beam) is irradiated while moving relative to the large area substrate. (FIG. 6A) At this time, since the length of the laser beam (laser beam) in the longitudinal direction is shorter than one side of the large-area substrate, it cannot be annealed only by scanning in one direction, and moves in at least two directions. As shown in FIG. 6B, a portion where scanning of laser light (laser beam) is adjacent is formed. However, the laser beam (laser beam) formed by the present invention is a laser beam (laser beam) having a sharp end, and does not have an attenuation region. Therefore, uniform annealing can be realized even at locations where scanning of laser light (laser beam) is adjacent. Therefore, a large-area substrate can be used without waste, and the throughput is remarkably improved.
[0064]
[Example 5]
In this embodiment, a method for manufacturing an active matrix substrate will be described with reference to FIGS. In this specification, a substrate in which a pixel portion having a CMOS circuit, a driver circuit, a pixel TFT, and a storage capacitor is formed over the same substrate is referred to as an active matrix substrate for convenience.
[0065]
First, in this embodiment, a substrate 400 made of glass such as barium borosilicate glass or alumino borosilicate glass is used. Note that the substrate 400 may be a quartz substrate, a silicon substrate, a metal substrate, or a stainless substrate on which an insulating film is formed. Further, a plastic substrate having heat resistance that can withstand the processing temperature of this embodiment may be used. Note that in the present invention, annealing can be performed using laser light (laser beam) with extremely excellent uniformity of energy distribution, and thus a large-area substrate can be used.
[0066]
Next, a base film 401 made of an insulating film such as a silicon oxide film, a silicon nitride film, or a silicon oxynitride film is formed over the substrate 400 by a known means. Although a two-layer structure is used as the base film 401 in this embodiment, a single-layer film of the insulating film or a structure in which two or more layers are stacked may be used.
[0067]
Next, semiconductor layers 402 to 406 are formed over the base film. The semiconductor layers 402 to 406 are formed by forming a semiconductor film with a thickness of 25 to 80 nm (preferably 30 to 60 nm) by a known means (such as sputtering, LPCVD, or plasma CVD), and crystallizing by laser crystallization. Make it. In the laser crystallization method, any one of Embodiments 1 to 4 is applied, and the semiconductor film is irradiated with laser light (laser beam) emitted from the laser. Of course, not only the laser crystallization method but also other known crystallization methods (thermal crystallization method using an RTA or furnace annealing furnace, thermal crystallization method using a metal element that promotes crystallization, etc.) You may go. Then, the obtained crystalline semiconductor film is patterned into a desired shape to form semiconductor layers 402 to 406. Examples of the semiconductor film include an amorphous semiconductor film, a microcrystalline semiconductor film, a crystalline semiconductor film, and the like, and a compound semiconductor film having an amorphous structure such as an amorphous silicon germanium film may be applied.
[0068]
In this embodiment, a 55 nm amorphous silicon film is formed by plasma CVD. Then, after dehydrogenating the amorphous silicon film (500 ° C., 1 hour), continuous oscillation YVO with an output of 10 W _Four After the laser beam (laser beam) emitted from the laser is converted into the second harmonic by the non-linear optical element, the laser beam (laser beam) is formed from the optical system shown in any one of the first to third embodiments. Irradiate. The energy density at this time is 0.01 to 100 MW / cm. ² Degree (preferably 0.1-10 MW / cm ² )is required. When an excimer laser is used, the pulse oscillation frequency is 300 Hz and the laser energy density is 100 to 1000 mJ / cm. ² (Typically 200-700mJ / cm ² ) Is desirable. Then, irradiation is performed by moving the stage relative to the laser beam (laser beam) at a speed of about 0.5 to 2000 cm / s to form a crystalline silicon film. Then, the semiconductor layers 402 to 406 are formed by a patterning process using a photolithography method.
[0069]
Further, after forming the semiconductor layers 402 to 406, a small amount of impurity element (boron or phosphorus) may be doped in order to control the threshold value of the TFT.
[0070]
Next, a gate insulating film 407 covering the semiconductor layers 402 to 406 is formed. The gate insulating film 407 is formed of an insulating film containing silicon with a thickness of 40 to 150 nm by plasma CVD or sputtering. In this embodiment, a silicon oxynitride film (composition ratio: Si = 32%, O = 59%, N = 7%, H = 2%) with a thickness of 110 nm is formed by plasma CVD. Needless to say, the gate insulating film is not limited to the silicon oxynitride film, and another insulating film containing silicon may be used as a single layer or a stacked structure.
[0071]
When a silicon oxide film is used, TEOS (Tetraethyl Orthosilicate) and O ₂ The reaction pressure is 40 Pa, the substrate temperature is 300 to 400 ° C., and the high frequency (13.56 MHz) power density is 0.5 to 0.8 W / cm. ² And can be formed by discharging. The silicon oxide film thus manufactured can obtain good characteristics as a gate insulating film by thermal annealing at 400 to 500 ° C. thereafter.
[0072]
Next, a first conductive film 408 with a thickness of 20 to 100 nm and a second conductive film 409 with a thickness of 100 to 400 nm are stacked over the gate insulating film 407. In this embodiment, a first conductive film 408 made of a TaN film with a thickness of 30 nm and a second conductive film 409 made of a W film with a thickness of 370 nm are stacked. The TaN film is formed by sputtering, and is sputtered in a nitrogen-containing atmosphere using a Ta target. The W film was formed by sputtering using a W target. In addition, tungsten hexafluoride (WF ₆ It can also be formed by a thermal CVD method using In any case, in order to use as a gate electrode, it is necessary to reduce the resistance, and the resistivity of the W film is desirably 20 μΩcm or less.
[0073]
In this embodiment, the first conductive film 408 is TaN and the second conductive film 409 is W. However, there is no particular limitation, and all are Ta, W, Ti, Mo, Al, Cu, Cr, Nd. You may form with the element selected from these, or the alloy material or compound material which has the said element as a main component. Alternatively, a semiconductor film typified by a polycrystalline silicon film doped with an impurity element such as phosphorus may be used. Further, an AgPdCu alloy may be used.
[0074]
Next, resist masks 410 to 415 are formed by photolithography, and a first etching process is performed to form electrodes and wirings. The first etching process is performed under the first and second etching conditions. (FIG. 10 (B)) In this embodiment, ICP (Inductively Coupled Plasma) etching is used as the first etching condition, and CF is used as an etching gas. _Four And Cl ₂ And O ₂ The gas flow ratio is 25:25:10 (sccm), and 500 W of RF (13.56 MHz) power is applied to the coil-type electrode at a pressure of 1 Pa to generate plasma and perform etching. 150 W RF (13.56 MHz) power is also applied to the substrate side (sample stage), and a substantially negative self-bias voltage is applied. The W film is etched under this first etching condition so that the end portion of the first conductive layer is tapered.
[0075]
Thereafter, the resist masks 410 to 415 are not removed and the second etching condition is changed, and the etching gas is changed to CF. _Four And Cl ₂ The gas flow ratio is 30:30 (sccm), and 500 W of RF (13.56 MHz) power is applied to the coil-type electrode at a pressure of 1 Pa to generate plasma and etching for about 30 seconds. I do. 20 W of RF (13.56 MHz) power is also applied to the substrate side (sample stage), and a substantially negative self-bias voltage is applied. CF _Four And Cl ₂ Under the second etching condition in which is mixed, the W film and the TaN film are etched to the same extent. Note that in order to perform etching without leaving a residue on the gate insulating film, it is preferable to increase the etching time at a rate of about 10 to 20%.
[0076]
In the first etching process, the shape of the mask made of resist is made suitable, and the end portions of the first conductive layer and the second conductive layer are tapered due to the effect of the bias voltage applied to the substrate side. It becomes. The angle of this taper portion is 15 to 45 °. Thus, the first shape conductive layers 417 to 422 (the first conductive layers 417 a to 422 a and the second conductive layers 417 b to 422 b) composed of the first conductive layer and the second conductive layer by the first etching treatment. Form. Reference numeral 416 denotes a gate insulating film, and a region not covered with the first shape conductive layers 417 to 422 is etched and thinned by about 20 to 50 nm.
[0077]
Next, a second etching process is performed without removing the resist mask. Here, CF is used as an etching gas. _Four And Cl ₂ And O ₂ Then, the W film is selectively etched. At this time, second conductive layers 428b to 433b are formed by a second etching process. On the other hand, the first conductive layers 417a to 422a are hardly etched, and the second shape conductive layers 428 to 433 are formed.
[0078]
Then, a first doping process is performed without removing the resist mask, and an impurity element imparting n-type conductivity is added to the semiconductor layer at a low concentration. The doping process may be performed by ion doping or ion implantation. The condition of the ion doping method is a dose of 1 × 10 ¹³ ~ 5x10 ¹⁴ / Cm ² The acceleration voltage is set to 40 to 80 keV. In this embodiment, the dose is 1.5 × 10 ¹³ / Cm ² And the acceleration voltage is 60 keV. As an impurity element imparting n-type, an element belonging to Group 15, typically phosphorus (P) or arsenic (As), is used here, but phosphorus (P) is used. In this case, the conductive layers 428 to 433 serve as a mask for the impurity element imparting n-type, and the impurity regions 423 to 427 are formed in a self-aligning manner. Impurity regions 423 to 427 have 1 × 10 ¹⁸ ~ 1x10 ²⁰ /cm ^Three An impurity element imparting n-type is added in a concentration range of.
[0079]
After removing the resist mask, new resist masks 434a to 434c are formed, and the second doping process is performed at an acceleration voltage higher than that of the first doping process. The condition of the ion doping method is a dose of 1 × 10 ¹³ ~ 1x10 ¹⁵ /cm ² The acceleration voltage is set to 60 to 120 keV. In the doping treatment, the second conductive layers 428b to 432b are used as masks against the impurity element, and doping is performed so that the impurity element is added to the semiconductor layer below the tapered portion of the first conductive layer. Subsequently, the third doping process is performed by lowering the acceleration voltage than the second doping process to obtain the state of FIG. The condition of the ion doping method is a dose of 1 × 10 ¹⁵ ~ 1x10 ¹⁷ /cm ² The acceleration voltage is set to 50 to 100 keV. The low-concentration impurity regions 436, 442, and 448 overlapping with the first conductive layer by the second doping process and the third doping process have 1 × 10 ¹⁸ ~ 5x10 ¹⁹ /cm ^Three An impurity element imparting n-type is added in the concentration range of 1 × 10 in the high-concentration impurity regions 435, 438, 441, 444, and 447. ¹⁹ ~ 5x10 ^{twenty one} /cm ^Three An impurity element imparting n-type is added in a concentration range of.
[0080]
Needless to say, by setting the acceleration voltage to be appropriate, the second and third doping processes can be performed in a single doping process to form the low-concentration impurity region and the high-concentration impurity region.
[0081]
Next, after removing the resist mask, new resist masks 450a to 450c are formed, and a fourth doping process is performed. By this fourth doping treatment, impurity regions 453 to 455, 459, and 460 in which an impurity element imparting a conductivity type opposite to the one conductivity type is added to the semiconductor layer that becomes the active layer of the p-channel TFT are formed. To do. The second conductive layers 428a to 432a are used as masks against the impurity element, and an impurity element imparting p-type is added to form an impurity region in a self-aligning manner. In this embodiment, the impurity regions 453 to 455, 459, and 460 are diborane (B ₂ H ₆ ) Using an ion doping method. (FIG. 11B) In the fourth doping process, the semiconductor layer forming the n-channel TFT is covered with masks 450a to 450c made of resist. Phosphorus is added to the impurity regions 439, 447, and 448 at different concentrations by the first to third doping treatments, and the concentration of the impurity element imparting p-type in each of the regions is 1 × 10. ¹⁹ ~ 5x10 ^{twenty one} atoms / cm ^Three By performing the doping treatment so as to become, no problem arises because it functions as the source region and drain region of the p-channel TFT.
[0082]
Through the above steps, impurity regions are formed in the respective semiconductor layers.
[0083]
Next, the resist masks 450 a to 450 c are removed, and a first interlayer insulating film 461 is formed. The first interlayer insulating film 461 is formed of an insulating film containing silicon with a thickness of 100 to 200 nm using a plasma CVD method or a sputtering method. In this embodiment, a silicon oxynitride film having a thickness of 150 nm is formed by a plasma CVD method. Needless to say, the first interlayer insulating film 461 is not limited to the silicon oxynitride film, and another insulating film containing silicon may be used as a single layer or a stacked structure.
[0084]
Next, as shown in FIG. 11C, laser light (laser beam) is irradiated to recover the crystallinity of the semiconductor layers and to activate the impurity elements added to the respective semiconductor layers. At this time, the energy density of the laser beam (laser beam) is 0.01 to 100 MW / cm. ² Degree (preferably 0.01 to 10 MW / cm ² ) And the substrate is moved at a speed of 0.5 to 2000 cm / s relative to the laser beam (laser beam). In addition to the laser annealing method, a thermal annealing method, a rapid thermal annealing method (RTA method), or the like can be applied.
[0085]
Further, heat treatment may be performed before the first interlayer insulating film is formed. However, when the wiring material used is weak against heat, it is activated after an interlayer insulating film (insulating film containing silicon as a main component, for example, a silicon nitride film) is formed to protect the wiring as in this embodiment. It is preferable to perform the conversion treatment.
[0086]
Then, hydrogenation can be performed by heat treatment (heat treatment at 300 to 550 ° C. for 1 to 12 hours). This step is a step of terminating dangling bonds in the semiconductor layer with hydrogen contained in the first interlayer insulating film 461. The semiconductor layer can be hydrogenated regardless of the presence of the first interlayer insulating film. As other means for hydrogenation, plasma hydrogenation (using hydrogen excited by plasma) or heat treatment at 300 to 450 ° C. for 1 to 12 hours in an atmosphere containing 3 to 100% hydrogen may be performed. .
[0087]
Next, a second interlayer insulating film 462 made of an inorganic insulating film material or an organic insulating material is formed over the first interlayer insulating film 461. In this embodiment, an acrylic resin film having a thickness of 1.6 μm is formed, but a film having a viscosity of 10 to 1000 cp, preferably 40 to 200 cp, and having a surface with unevenness is used.
[0088]
In this embodiment, in order to prevent specular reflection, the surface of the pixel electrode is formed with the unevenness by forming the second interlayer insulating film having the unevenness on the surface. In addition, a convex portion may be formed in a region below the pixel electrode in order to make the surface of the pixel electrode uneven to achieve light scattering. In that case, since the convex portion can be formed using the same photomask as that of the TFT, it can be formed without increasing the number of steps. In addition, this convex part should just be suitably provided on the board | substrate of pixel part area | regions other than wiring and a TFT part. Thus, irregularities are formed on the surface of the pixel electrode along the irregularities formed on the surface of the insulating film covering the convex portions.
[0089]
Alternatively, a film whose surface is planarized may be used as the second interlayer insulating film 462. In that case, after forming the pixel electrode, adding a step such as a known sandblasting method or etching method to make the surface uneven, prevent specular reflection, and increase the whiteness by scattering the reflected light Is preferred.
[0090]
In the driver circuit 506, wirings 463 to 467 that are electrically connected to the impurity regions are formed. Note that these wirings are formed by patterning a laminated film of a Ti film having a thickness of 50 nm and an alloy film (alloy film of Al and Ti) having a thickness of 500 nm. Of course, not only a two-layer structure but also a single-layer structure or a laminated structure of three or more layers may be used. Further, the wiring material is not limited to Al and Ti. For example, a wiring may be formed by patterning a laminated film in which Al or Cu is formed on a TaN film and a Ti film is further formed. (Fig. 12)
[0091]
In the pixel portion 507, a pixel electrode 470, a gate wiring 469, and a connection electrode 468 are formed. With this connection electrode 468, the source wiring (stacked layer of 443a and 443b) is electrically connected to the pixel TFT. In addition, the gate wiring 469 is electrically connected to the gate electrode of the pixel TFT. In addition, the pixel electrode 470 is electrically connected to the drain region 471 of the pixel TFT, and is further electrically connected to the semiconductor layer 459 functioning as one electrode forming a storage capacitor. Further, as the pixel electrode 470, it is desirable to use a highly reflective material such as a film containing Al or Ag as a main component or a laminated film thereof.
[0092]
As described above, a CMOS circuit including an n-channel TFT 501 and a p-channel TFT 502, a driver circuit 506 having an n-channel TFT 503, and a pixel portion 507 having a pixel TFT 504 and a storage capacitor 505 are formed over the same substrate. can do. Thus, the active matrix substrate is completed.
[0093]
The n-channel TFT 501 of the driver circuit 506 includes a channel formation region 437, a low-concentration impurity region 436 (GOLD region) that overlaps with the first conductive layer 428a that forms part of the gate electrode, and a high-concentration function as a source region or a drain region. And an impurity region 452. The p-channel TFT 502, which is connected to the n-channel TFT 501 and the electrode 466 to form a CMOS circuit, has a low-concentration impurity region 453 that overlaps with the channel formation region 440 and the first conductive layer 429a that forms part of the gate electrode. GOLD region) and a high concentration impurity region 453 functioning as a source region or a drain region. In the n-channel TFT 503, a channel formation region 443, a low concentration impurity region 442 (GOLD region) overlapping with the first conductive layer 430a which forms part of the gate electrode, and a high concentration impurity functioning as a source region or a drain region Region 456.
[0094]
The pixel TFT 504 in the pixel portion includes a channel formation region 446, a low concentration impurity region 445 (LDD region) formed outside the gate electrode, and a high concentration impurity region 458 functioning as a source region or a drain region. In addition, an impurity element imparting n-type conductivity and an impurity element imparting p-type conductivity are added to the semiconductor layer functioning as one electrode of the storage capacitor 505. The storage capacitor 505 is formed of an electrode (stack of 432a and 432b) and a semiconductor layer using the insulating film 416 as a dielectric.
[0095]
In the pixel structure of this embodiment, the end portions of the pixel electrodes are arranged and formed so as to overlap the source wiring so that the gap between the pixel electrodes is shielded from light without using a black matrix.
[0096]
FIG. 13 shows a top view of a pixel portion of an active matrix substrate manufactured in this embodiment. In addition, the same code | symbol is used for the part corresponding to FIGS. A chain line AA ′ in FIG. 12 corresponds to a cross-sectional view taken along the chain line AA ′ in FIG. Further, a chain line BB ′ in FIG. 12 corresponds to a cross-sectional view taken along the chain line BB ′ in FIG.
[0097]
[Example 6]
In this embodiment, a process for manufacturing a reflective liquid crystal display device from the active matrix substrate manufactured in Embodiment 5 will be described below. FIG. 14 is used for the description.
[0098]
First, after obtaining the active matrix substrate in the state of FIG. 12 according to Embodiment 5, an alignment film 567 is formed on at least the pixel electrode 470 on the active matrix substrate of FIG. In this embodiment, before forming the alignment film 567, an organic resin film such as an acrylic resin film is patterned to form columnar spacers 572 for maintaining a substrate interval at a desired position. Further, instead of the columnar spacers, spherical spacers may be scattered over the entire surface of the substrate.
[0099]
Next, a counter substrate 569 is prepared. Next, colored layers 570 and 571 and a planarization film 573 are formed over the counter substrate 569. The red colored layer 570 and the blue colored layer 571 are overlapped to form a light shielding portion. Further, the light shielding portion may be formed by partially overlapping the red colored layer and the green colored layer.
[0100]
In this example, the substrate shown in Example 5 is used. Therefore, in FIG. 13 showing a top view of the pixel portion of Example 5, at least the gap between the gate wiring 469 and the pixel electrode 470, the gap between the gate wiring 469 and the connection electrode 468, and the gap between the connection electrode 468 and the pixel electrode 470 are shown. It is necessary to shield the light. In this example, the respective colored layers were arranged so that the light-shielding portions formed by the lamination of the colored layers overlapped at the positions where light shielding should be performed, and the counter substrate was bonded.
[0101]
As described above, the number of steps can be reduced by shielding the gap between the pixels with the light shielding portion formed by the lamination of the colored layers without forming a light shielding layer such as a black mask.
[0102]
Next, a counter electrode 576 made of a transparent conductive film was formed over the planarization film 573 in at least the pixel portion, an alignment film 574 was formed over the entire surface of the counter substrate, and a rubbing process was performed.
[0103]
Then, the active matrix substrate on which the pixel portion and the driver circuit are formed and the counter substrate are attached to each other with a sealant 568. A filler is mixed in the sealing material 568, and two substrates are bonded to each other with a uniform interval by the filler and the columnar spacer. Thereafter, a liquid crystal material 575 is injected between both substrates and completely sealed with a sealant (not shown). A known liquid crystal material may be used for the liquid crystal material 575. In this way, the reflection type liquid crystal display device shown in FIG. 14 is completed. If necessary, the active matrix substrate or the counter substrate is divided into a desired shape. Further, a polarizing plate (not shown) was attached only to the counter substrate. And FPC was affixed using the well-known technique.
[0104]
Since the liquid crystal display device manufactured as described above is irradiated with a laser beam (laser beam) having a very excellent uniformity of energy distribution, a TFT manufactured using a uniformly annealed semiconductor film is not used. Therefore, the operation characteristics and reliability of the liquid crystal display device can be sufficient. And such a liquid crystal display device can be used as a display part of various electronic devices.
[0105]
Note that this embodiment can be freely combined with Embodiments 1 to 5.
[0106]
[Example 7]
In this embodiment, an example in which a light-emitting device is manufactured using the method for manufacturing a TFT when manufacturing an active matrix substrate shown in Embodiment 5 will be described. In this specification, the light emitting device is a general term for a display panel in which a light emitting element formed on a substrate is sealed between the substrate and a cover material, and a display module including a TFT in the display panel. is there. Note that the light-emitting element includes a layer (light-emitting body) containing a compound capable of obtaining luminescence (Electro Luminescence) generated by applying an electric field, an anode layer, and a cathode layer. In addition, the luminescence of the compound includes light emission (fluorescence) when returning from the singlet excited state to the ground state and light emission (phosphorescence) when returning from the triplet excited state to the ground state. Includes both emissions.
[0107]
Note that in this specification, all layers formed between an anode and a cathode in a light-emitting element are defined as light emitters. Specifically, the light emitter includes a light emitting layer, a hole injection layer, an electron injection layer, a hole transport layer, an electron transport layer, and the like. Basically, a light emitting element has a structure in which an anode layer, a light emitting layer, and a cathode layer are sequentially laminated. In addition to this structure, an anode layer, a hole injection layer, a light emitting layer, a cathode layer, and an anode layer , A hole injection layer, a light emitting layer, an electron transport layer, a cathode layer and the like may be laminated in this order.
[0108]
FIG. 15 is a cross-sectional view of the light emitting device of this example. In FIG. 15, a switching TFT 603 provided over a substrate 700 is formed using the n-channel TFT 503 in FIG. Therefore, the description of the n-channel TFT 503 may be referred to for the description of the structure.
[0109]
Note that although a double gate structure in which two channel formation regions are formed is used in this embodiment, a single gate structure in which one channel formation region is formed or a triple gate structure in which three channel formation regions are formed may be used.
[0110]
A driver circuit provided over the substrate 700 is formed using the CMOS circuit of FIG. Therefore, for the description of the structure, the description of the n-channel TFT 501 and the p-channel TFT 502 may be referred to. In this embodiment, a single gate structure is used, but a double gate structure or a triple gate structure may be used.
[0111]
Further, the wirings 701 and 703 function as source wirings of the CMOS circuit, and the wiring 702 functions as a drain wiring. The wiring 704 functions as a wiring that electrically connects the source wiring 708 and the source region of the switching TFT, and the wiring 705 functions as a wiring that electrically connects the drain wiring and the drain region of the switching TFT.
[0112]
Note that the current control TFT 604 is formed using the p-channel TFT 502 of FIG. Accordingly, the description of the p-channel TFT 502 may be referred to for the description of the structure. In this embodiment, a single gate structure is used, but a double gate structure or a triple gate structure may be used.
[0113]
A wiring 706 is a source wiring (corresponding to a current supply line) of the current control TFT, and 707 is an electrode that is electrically connected to the pixel electrode 711 by being overlaid on the pixel electrode 711 of the current control TFT.
[0114]
Reference numeral 711 denotes a pixel electrode (anode of the light emitting element) made of a transparent conductive film. As the transparent conductive film, a compound of indium oxide and tin oxide, a compound of indium oxide and zinc oxide, zinc oxide, tin oxide, or indium oxide can be used. Moreover, you may use what added the gallium to the said transparent conductive film. The pixel electrode 711 is formed on the flat interlayer insulating film 710 before forming the wiring. In this embodiment, it is very important to flatten the step due to the TFT using the flattening film 710 made of resin. Since the light emitting layer formed later is very thin, the presence of a step may cause a light emission failure. Therefore, it is desirable to planarize the pixel electrode before forming it so that the light emitting layer can be formed as flat as possible.
[0115]
After the wirings 701 to 707 are formed, a bank 712 is formed as shown in FIG. The bank 712 may be formed by patterning an insulating film or organic resin film containing silicon of 100 to 400 nm.
[0116]
Note that since the bank 712 is an insulating film, attention must be paid to electrostatic breakdown of elements during film formation. In this embodiment, carbon particles or metal particles are added to the insulating film that is the material of the bank 712 to reduce the resistivity and suppress the generation of static electricity. At this time, the resistivity is 1 × 10 ⁶ ~ 1x10 ¹² Ωm (preferably 1 × 10 ⁸ ~ 1x10 ^Ten The added amount of carbon particles and metal particles may be adjusted so that the resistance becomes Ωm).
[0117]
A light emitter 713 is formed on the pixel electrode 711. Although only one pixel is shown in FIG. 15, in this embodiment, light emitters corresponding to the respective colors of R (red), G (green), and B (blue) are separately created. In this embodiment, a low molecular weight organic light emitting material is formed by a vapor deposition method. Specifically, a copper phthalocyanine (CuPc) film having a thickness of 20 nm is provided as a hole injection layer, and a tris-8-quinolinolato aluminum complex (Alq) having a thickness of 70 nm is formed thereon as a light emitting layer. _Three ) A laminated structure provided with a film. Alq _Three The emission color can be controlled by adding a fluorescent dye such as quinacridone, perylene, or DCM1.
[0118]
However, the above example is an example of an organic light emitting material that can be used as a light emitter, and is not necessarily limited to this. A light-emitting body (a layer for emitting light and moving carriers therefor) may be formed by freely combining a light-emitting layer, a charge transport layer, or a charge injection layer. For example, in this embodiment, an example in which a low molecular weight organic light emitting material is used as the light emitting layer is shown, but a medium molecular weight organic light emitting material or a high molecular weight organic light emitting material may be used. Note that in this specification, an organic light-emitting material that does not have sublimation and has 20 or less molecules or a chain molecule length of 10 μm or less is referred to as a medium molecular organic light-emitting material. As an example of using a polymer organic light emitting material, a 20 nm polythiophene (PEDOT) film is provided by a spin coating method as a hole injection layer, and a paraphenylene vinylene (PPV) film of about 100 nm is provided thereon as a light emitting layer. Alternatively, a laminated structure may be used. If a PPV π-conjugated polymer is used, the emission wavelength can be selected from red to blue. It is also possible to use an inorganic material such as silicon carbide for the charge transport layer or the charge injection layer. Known materials can be used for these organic light emitting materials and inorganic materials.
[0119]
Next, a cathode 714 made of a conductive film is provided on the light emitter 713. In this embodiment, an alloy film of aluminum and lithium is used as the conductive film. Of course, a known MgAg film (magnesium and silver alloy film) may be used. As the cathode material, a conductive film made of an element belonging to Group 1 or Group 2 of the periodic table or a conductive film added with these elements may be used.
[0120]
When the cathode 714 is formed, the light emitting element 715 is completed. Note that the light-emitting element 715 here refers to a diode formed of a pixel electrode (anode) 711, a light-emitting layer 713, and a cathode 714.
[0121]
It is effective to provide a passivation film 716 so as to completely cover the light emitting element 715. As the passivation film 716, an insulating film including a carbon film, a silicon nitride film, or a silicon nitride oxide film is used, and the insulating film is used as a single layer or a combination thereof.
[0122]
At this time, it is preferable to use a film with good coverage as the passivation film, and it is effective to use a carbon film, particularly a DLC (diamond-like carbon) film. Since the DLC film can be formed in a temperature range from room temperature to 100 ° C., it can be easily formed over the light-emitting layer 713 having low heat resistance. In addition, the DLC film has a high blocking effect against oxygen and can suppress oxidation of the light-emitting layer 713. Therefore, the problem that the light emitting layer 713 is oxidized during the subsequent sealing process can be prevented.
[0123]
Further, a sealing material 717 is provided over the passivation film 716 and a cover material 718 is attached thereto. As the sealing material 717, an ultraviolet curable resin may be used, and it is effective to provide a substance having a hygroscopic effect or a substance having an antioxidant effect inside. In this embodiment, the cover material 718 is formed by forming a carbon film (preferably a diamond-like carbon film) on both surfaces of a glass substrate, a quartz substrate, or a plastic substrate (including a plastic film).
[0124]
Thus, a light emitting device having a structure as shown in FIG. 15 is completed. Note that it is effective to continuously process the steps from the formation of the bank 712 to the formation of the passivation film 716 using a multi-chamber type (or in-line type) film formation apparatus without releasing to the atmosphere. . Further, it is possible to continuously process the process up to the step of bonding the cover material 718 without releasing to the atmosphere.
[0125]
Thus, an n-channel TFT 601, a p-channel TFT 602, a switching TFT (n-channel TFT) 603 and a current control TFT (n-channel TFT) 604 are formed on the substrate 700.
[0126]
Furthermore, as described with reference to FIGS. 15A and 15B, an n-channel TFT which is resistant to deterioration due to the hot carrier effect can be formed by providing an impurity region overlapping with the gate electrode through an insulating film. Therefore, a highly reliable light emitting device can be realized.
[0127]
In addition, in this embodiment, only the configuration of the pixel portion and the drive circuit is shown. However, according to the manufacturing process of this embodiment, other logic circuits such as a signal dividing circuit, a D / A converter, an operational amplifier, and a γ correction circuit are provided. Can be formed on the same insulator, and a memory and a microprocessor can also be formed.
[0128]
The light emitting device manufactured as described above has a TFT manufactured using a uniformly annealed semiconductor film because it is irradiated with a laser beam (laser beam) with excellent uniformity of energy distribution. Therefore, the operating characteristics and reliability of the light emitting device can be sufficient. And such a light-emitting device can be used as a display part of various electronic devices.
[0129]
Note that this embodiment can be freely combined with Embodiments 1 to 5.
[0130]
[Example 8]
By applying the present invention, various semiconductor devices (active matrix liquid crystal display device, active matrix light emitting device, active matrix EC display device) can be manufactured. That is, the present invention can be applied to various electronic devices in which these electro-optical devices are incorporated in a display unit.
[0131]
Such electronic devices include video cameras, digital cameras, projectors, head-mounted displays (goggles type displays), car navigation systems, car stereos, personal computers, personal digital assistants (mobile computers, mobile phones, electronic books, etc.), etc. Can be mentioned. Examples thereof are shown in FIGS. 16, 17 and 18.
[0132]
FIG. 16A illustrates a personal computer, which includes a main body 3001, an image input portion 3002, a display portion 3003, a keyboard 3004, and the like. The present invention can be applied to the display portion 3003.
[0133]
FIG. 16B illustrates a video camera, which includes a main body 3101, a display portion 3102, an audio input portion 3103, operation switches 3104, a battery 3105, an image receiving portion 3106, and the like. The present invention can be applied to the display portion 3102.
[0134]
FIG. 16C illustrates a mobile computer, which includes a main body 3201, a camera unit 3202, an image receiving unit 3203, an operation switch 3204, a display unit 3205, and the like. The present invention can be applied to the display portion 3205.
[0135]
FIG. 16D illustrates a goggle type display, which includes a main body 3301, a display portion 3302, an arm portion 3303, and the like. The present invention can be applied to the display portion 3302.
[0136]
FIG. 16E shows a player using a recording medium (hereinafter referred to as a recording medium) on which a program is recorded, and includes a main body 3401, a display portion 3402, a speaker portion 3403, a recording medium 3404, an operation switch 3405, and the like. This player uses a DVD (Digital Versatile Disc), CD, or the like as a recording medium, and can perform music appreciation, movie appreciation, games, and the Internet. The present invention can be applied to the display portion 3402.
[0137]
FIG. 16F illustrates a digital camera, which includes a main body 3501, a display portion 3502, an eyepiece portion 3503, an operation switch 3504, an image receiving portion (not shown), and the like. The present invention can be applied to the display portion 3502.
[0138]
FIG. 17A illustrates a front type projector, which includes a projection device 3601, a screen 3602, and the like. The present invention can be applied to a liquid crystal display device 3808 constituting a part of the projection device 3601 and other driving circuits.
[0139]
FIG. 17B shows a rear projector, which includes a main body 3701, a projection device 3702, a mirror 3703, a screen 3704, and the like. The present invention can be applied to the liquid crystal display device 3808 constituting a part of the projection device 3702 and other driving circuits.
[0140]
Note that FIG. 17C illustrates an example of the structure of the projection devices 3601 and 3702 in FIGS. 17A and 17B. The projection devices 3601 and 3702 include a light source optical system 3801, mirrors 3802 and 3804 to 3806, a dichroic mirror 3803, a prism 3807, a liquid crystal display device 3808, a phase difference plate 3809, and a projection optical system 3810. The projection optical system 3810 is composed of an optical system including a projection lens. Although the present embodiment shows a three-plate type example, it is not particularly limited, and for example, a single-plate type may be used. In addition, the practitioner may appropriately provide an optical system such as an optical lens, a film having a polarizing function, a film for adjusting a phase difference, or an IR film in the optical path indicated by an arrow in FIG. Good.
[0141]
FIG. 17D illustrates an example of the structure of the light source optical system 3801 in FIG. In this embodiment, the light source optical system 3801 includes a reflector 3811, a light source 3812, lens arrays 3813 and 3814, a polarization conversion element 3815, and a condenser lens 3816. Note that the light source optical system illustrated in FIG. 17D is an example and is not particularly limited. For example, the practitioner may appropriately provide an optical system such as an optical lens, a film having a polarization function, a film for adjusting a phase difference, or an IR film in the light source optical system.
[0142]
However, the projector shown in FIG. 17 shows a case where a transmissive electro-optical device is used, and an application example in a reflective electro-optical device and a light-emitting device is not shown.
[0143]
FIG. 18A illustrates a mobile phone, which includes a main body 3901, an audio output portion 3902, an audio input portion 3903, a display portion 3904, operation switches 3905, an antenna 3906, and the like. The present invention can be applied to the display portion 3904.
[0144]
FIG. 18B illustrates a portable book (electronic book), which includes a main body 4001, display portions 4002 and 4003, a storage medium 4004, operation switches 4005, an antenna 4006, and the like. The present invention can be applied to the display portions 4002 and 4003.
[0145]
FIG. 18C illustrates a display, which includes a main body 4101, a support base 4102, a display portion 4103, and the like. The present invention can be applied to the display portion 4103. The display of the present invention is particularly advantageous when the screen is enlarged, and is advantageous for displays having a diagonal of 10 inches or more (particularly 30 inches or more).
[0146]
As described above, the applicable range of the present invention is so wide that the present invention can be applied to electronic devices in various fields. Moreover, the electronic device of a present Example is realizable even if it uses the structure which consists of a combination of Example 1-6 or 7th.
[0147]
【The invention's effect】
By adopting the configuration of the present invention, the following basic significance can be obtained.
(A) It is possible to form a laser beam (laser beam) having a very excellent energy density distribution on the irradiated surface or a plane in the vicinity thereof.
(B) It is possible to uniformly anneal the irradiated object. This is particularly effective for large area substrates.
(C) The throughput can be improved.
(D) In a semiconductor device typified by an active matrix liquid crystal display device, the operating characteristics and reliability of the semiconductor device can be improved while satisfying the above advantages. Furthermore, the manufacturing cost of the semiconductor device can be reduced.
[Brief description of the drawings]
FIG. 1A is a diagram showing an example of an optical path when a slit is installed.
(B) The figure which shows the example of the optical path when installing a mirror.
FIG. 2A is a view showing an example of energy density distribution of laser light (laser beam) in the present invention.
FIG. 3B is a diagram showing an example of annealing a large area substrate with the laser beam (laser beam) shown in FIG.
FIG. 3 is a diagram showing an example of an optical system of the present invention.
FIG. 4 is a diagram showing an example of an optical system of the present invention.
FIG. 5 is a diagram showing an example of a fly-eye lens.
FIG. 6 is a diagram showing an example of annealing a large-area substrate with a laser beam (laser beam) formed according to the present invention.
FIG. 7 is a diagram showing an example of a conventional optical system.
FIG. 8A is a diagram showing an example of energy density distribution of laser light (laser beam) formed by a conventional optical system.
FIG. 9B is a diagram showing an example of annealing a large-area substrate with the laser light (laser beam) shown in FIG.
FIG. 9 illustrates an example of a large area substrate.
FIG. 10 is a cross-sectional view illustrating a manufacturing process of a pixel TFT and a TFT of a driver circuit.
FIG. 11 is a cross-sectional view illustrating a manufacturing process of a pixel TFT and a TFT of a driver circuit.
12 is a cross-sectional view illustrating a manufacturing process of a pixel TFT and a TFT of a driver circuit. FIG.
FIG. 13 is a top view illustrating a structure of a pixel TFT.
FIG. 14 is a cross-sectional view of an active matrix liquid crystal display device.
FIG. 15 is a cross-sectional structure diagram of a driver circuit and a pixel portion of a light-emitting device.
FIG 16 illustrates an example of a semiconductor device.
FIG 17 illustrates an example of a semiconductor device.
FIG 18 illustrates an example of a semiconductor device.
FIG. 19 is a diagram showing an example of a homogenizer.

Claims (22)

The first means, the distribution of the Rue energy density put on the surface which is irradiated with the laser beam emitted from the laser, the energy density by forming a first laser beam to be homogenized regions and attenuation region,
The second means reinforces the attenuation region and forms a second laser beam having a uniform energy density in the attenuation region ,
Irradiating the irradiated surface with the second laser beam ;
The laser irradiation method, wherein the second means is a mirror installed in the vicinity of the irradiated surface . The first means forms a first linear laser beam with the energy density distribution on the irradiated surface of the laser beam emitted from the laser as a region where the energy density is made uniform and an attenuation region,
The second means reinforces the attenuation region, and forms a second linear laser beam having a uniform energy density in the attenuation region,
Irradiating the second linear laser beam while moving relative to the irradiated surface;
The laser irradiation method, wherein the second means is a mirror installed in the vicinity of the irradiated surface. According to claim 1 or claim 2, wherein the first means includes a laser irradiation method, wherein the a laser beam arranged homogenizer so as to be perpendicular to the optical axis of the. According to claim 1 or claim 2, said first means, said are arranged in parallel so as to be perpendicular to the laser beam of the optical axis, a plurality of cylindrical lens array for dividing the laser beam in the arrangement direction A characteristic laser irradiation method. According to claim 1 or claim 2, wherein the first means are arranged in parallel so as to be perpendicular to the optical axis of the laser beam, and a plurality of cylindrical lens group for dividing the laser beam in the arrangement direction, the cylindrical A laser irradiation method comprising: a lens arranged on a transmission side of a lens group, and a lens for synthesizing the divided laser beams. 2. The laser irradiation method according to claim 1 , wherein the first means is a fly-eye lens that is arranged so as to be orthogonal to the optical axis of the laser beam and divides the laser beam. 2. The first means according to claim 1 , wherein the first means is disposed so as to be orthogonal to the optical axis of the laser beam, and is arranged on the transmission side of the fly-eye lens and the fly-eye lens that divides the laser beam. And a spherical lens for combining the laser beams. In any one of claims 1 to 7, wherein the laser is a laser irradiation method which is a solid state laser or a gas laser of a continuous oscillation or pulse oscillation. In any one of claims 1 to 7, wherein the laser, YAG laser of a continuous oscillation or pulse oscillation, YVO ₄ laser, YLF laser, YAlO ₃ laser, a glass laser, a ruby laser, an alexandrite laser, or Ti: A laser irradiation method characterized by being a sapphire laser. In any one of claims 1 to 7, wherein the laser is a laser irradiation method is characterized in that an excimer laser of continuous oscillation or pulse oscillation, Ar laser or Kr laser. 11. The laser irradiation method according to claim 1, wherein the mirror is disposed in the vicinity of the center of the width of the attenuation region. The first means, the distribution of the Rue energy density put on the surface which is irradiated with the laser beam emitted from the laser, the energy density by forming a first laser beam to be homogenized regions and attenuation region,
The second means reinforces the attenuation region and forms a second laser beam having a uniform energy density in the attenuation region ,
Irradiating the semiconductor film to be irradiated with the second laser beam ;
The method of manufacturing a semiconductor device, wherein the second means is a mirror installed in the vicinity of an irradiated surface . The first means forms a first linear laser beam with the energy density distribution on the irradiated surface of the laser beam emitted from the laser as a region where the energy density is made uniform and an attenuation region,
The second means reinforces the attenuation region, and forms a second linear laser beam having a uniform energy density in a part of the attenuation region,
Irradiating the second linear laser beam while moving relative to the semiconductor film serving as an irradiated surface,
The method of manufacturing a semiconductor device, wherein the second means is a mirror installed in the vicinity of an irradiated surface. According to claim 12 or claim 13, wherein the first means, method for manufacturing a semiconductor device, wherein the a laser beam arranged homogenizer so as to be perpendicular to the optical axis of the. According to claim 12 or claim 13, wherein the first means, characterized in that said are arranged in parallel so as to be perpendicular to the laser beam of the optical axis, a plurality of cylindrical lenses for dividing the laser beam in the arrangement direction A method for manufacturing a semiconductor device. In Claim 12 or Claim 13 , said 1st means is arranged in parallel so that it may intersect with the optical axis of said laser beam, and a plurality of cylindrical lens groups which divide said laser beam in the arrangement direction, and said cylindrical A method for manufacturing a semiconductor device, comprising: a lens that is disposed on a transmission side of a lens group and that combines the divided laser beams. 13. The method for manufacturing a semiconductor device according to claim 12 , wherein the first means is a fly-eye lens that is arranged so as to be orthogonal to the optical axis of the laser beam and divides the laser beam. 13. The first means according to claim 12 , wherein the first means is arranged so as to be orthogonal to the optical axis of the laser beam, and a fly-eye lens that divides the laser beam and a transmission side of the fly-eye lens that is divided. And a spherical lens for synthesizing the laser beam. According to any one of claims 12 to claim 18, wherein the laser is a method for manufacturing a semiconductor device which is a solid state laser or a gas laser of a continuous oscillation or pulse oscillation. According to any one of claims 12 to claim 18, wherein the laser, YAG laser of a continuous oscillation or pulse oscillation, YVO ₄ laser, YLF laser, YAlO ₃ laser, a glass laser, a ruby laser, an alexandrite laser, or Ti: A method for manufacturing a semiconductor device, which is a sapphire laser. According to any one of claims 12 to claim 18, wherein the laser is a method for manufacturing a semiconductor device, characterized in that an excimer laser of continuous oscillation or pulse oscillation, Ar laser or Kr laser. The method for manufacturing a semiconductor device according to claim 12, wherein the mirror is provided near a center of a width of the attenuation region.

Images