JP2004297058A - Beam homogenizer, laser irradiating device, and method of manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein a laser varies its oscillation condition, and a beam spot is changed in energy distribution on an irradiation target surface before and after a maintenance operation. <P>SOLUTION: In a beam spot forming optical system, a beam homogenizer is equipped with an optical waveguide that is provided with the two opposed reflecting planes, one end face through which a laser beam is introduced, and the other end face through which the laser beam is projected out. The other end face of the optical waveguide is formed into a curved end face. The optical waveguide is a circuit having a function to trap emitted light in a certain region and guides and transmits the energy flow of the emitted light in parallel with the axis of a route. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a beam homogenizer that makes the energy distribution of a beam spot on an irradiated surface uniform in a specific region. The present invention also relates to a laser irradiation apparatus for irradiating the irradiated surface with the beam spot and a method for manufacturing a semiconductor device using the laser irradiation apparatus.

In recent years, there has been a technique for performing laser annealing on an amorphous semiconductor film or a crystalline semiconductor film (a semiconductor film having a crystallinity such as a single crystal, a polycrystal, or a microcrystal) formed on an insulating substrate such as glass. Has been extensively studied. A silicon film is often used as the semiconductor film. The laser annealing here refers to a technique for recrystallizing 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. ing. Moreover, the technique applied to planarization and surface modification of a semiconductor substrate or a semiconductor film is also included.

A glass substrate is cheaper and more workable than a quartz substrate that has been frequently used in the past, and has an advantage that a large-area substrate can be easily manufactured. For this reason, the above research has been actively conducted. Lasers are preferred for crystallization because the glass substrate has a low melting point. The laser can give high energy only to the non-single-crystal semiconductor film without significantly changing the temperature of the substrate.

A crystalline silicon film formed by laser annealing has high mobility. Therefore, a thin film transistor (TFT) using this crystalline silicon film is actively used. For example, a monolithic liquid crystal electro-optical device for manufacturing TFTs for pixels and driving circuits on a single glass substrate, It is actively used for light emitting devices. Since the crystalline silicon film is made of a large number of crystal grains, it is called a polycrystalline silicon film or a polycrystalline semiconductor film.

Also, a pulsed laser beam with high output, such as an excimer laser, is processed by an optical system so that a square spot of several cm square or a rectangular shape with a length of 10 cm or more in the long side direction is formed on the irradiated surface. However, a method of performing laser annealing by scanning the irradiation position of the beam spot relative to the surface to be irradiated is preferable because it is excellent in mass productivity and industrially excellent. A rectangular beam spot having a particularly high aspect ratio is referred to as a linear beam spot.

In particular, when a linear beam spot is used, scanning is performed only in a direction perpendicular to the direction in which the beam width of the linear beam spot is long, unlike the case of using a dotted beam spot that requires scanning in front, rear, left, and right. Since a laser beam can be irradiated onto a large surface to be irradiated, high mass productivity can be obtained. The reason for scanning in the direction perpendicular to the long beam width is that it is the most efficient scanning direction. Due to this high productivity, it is becoming more common for laser annealing to use a linear beam spot obtained by processing a beam spot of a pulsed excimer laser with an appropriate optical system.

FIG. 7 shows an example of an optical system for processing the cross-sectional shape of the beam spot into a linear shape on the irradiated surface. The optical system shown in FIG. 7 is very general. The optical system not only converts the cross-sectional shape of the beam spot into a linear shape, but also at the same time achieves uniform energy of the beam spot on the irradiated surface. In general, an optical system that makes the energy distribution of a beam spot uniform is called a beam homogenizer. The optical system shown in FIG. 7 is also a beam homogenizer.

If a XeCl excimer laser (wavelength 308 nm) is used as a light source, the base material of the optical system is preferably all quartz, for example. This is because high transmittance can be obtained. Moreover, it is preferable to use a coating that can obtain a transmittance of 99% or more with respect to the wavelength of the excimer laser used. When another excimer laser having a shorter wavelength is used as a light source, high transmittance can be obtained by using a base material such as fluorite or MgF ₂ . However, since these base materials are crystals, it is necessary to pay attention to the selection of the cut surface and coating.

First, the side view of FIG. The laser beam emitted from the laser oscillator 1201 divides the laser beam spot in one direction by cylindrical lens arrays 1202a and 1202b. The direction will be referred to as the vertical direction. The vertical direction is bent in the direction of light bent by the mirror when the mirror enters the middle of the optical system. In this configuration, there are four divisions. These divided spots are once combined into one spot by the cylindrical lens 1204. The spot separated again is reflected by the mirror 1207 and then condensed again into one spot on the irradiated surface 1209 by the doublet cylindrical lens 1208. The doublet cylindrical lens refers to a lens composed of two cylindrical lenses. Thereby, the energy in the vertical direction of the linear beam spot is made uniform, and the length in the vertical direction is determined.

Next, a top view of FIG. 7B will be described. The laser beam emitted from the laser oscillator 1201 divides the spot of the laser beam in a direction perpendicular to the vertical direction by a cylindrical lens array 1203. The perpendicular direction is referred to as a lateral direction. The horizontal direction is bent in the direction of light bent by the mirror when the mirror enters the middle of the optical system. In this configuration, there are seven divisions. After that, the spots divided into seven by the cylindrical lens 1205 are combined into one at the irradiated surface 1209. The mirror 1207 and the subsequent lines are indicated by broken lines. The broken line indicates the exact optical path and the position of the lens and the irradiated surface when the mirror 1207 is not disposed. Thereby, the energy in the horizontal direction of the linear beam spot is made uniform, and the length in the horizontal direction is determined.

As described above, the cylindrical lens array 1202a, the cylindrical lens array 1202b, and the cylindrical lens array 1203 are lenses that divide the laser beam spot. The uniformity of the energy distribution of the obtained linear beam spot is determined by the number of divisions.

The above lenses are made of synthetic quartz in order to correspond to the XeCl excimer laser. In addition, the surface is coated so as to pass through the excimer laser well, whereby the transmittance of the excimer laser per lens becomes 99% or more.

The linear beam spot processed with the above configuration is irradiated while being gradually shifted in the short side direction of the beam spot. Then, for example, laser annealing can be performed on the entire surface of the non-single crystal silicon film to crystallize or improve crystallinity.

Some beam homogenizers use a reflecting mirror (see, for example, Patent Document 1).

JP 2001-216881 A

Currently, in a mass production factory, annealing of a semiconductor film is performed using a beam spot processed into a long line by the optical system as described above. However, the position of the surface where a uniform beam spot can be obtained changes depending on the repetition frequency of the pulsed excimer laser, or the window that blocks the gas and the outside air that is the laser medium of the excimer laser is cleaned. It cannot be said that the completeness as a mass production apparatus is so high that the uniformity of the beam spot deteriorates.

The present invention has been made in view of the above problems, and an object of the present invention is to suppress changes in the oscillation state of an excimer laser and changes in the energy distribution of a beam spot on an irradiated surface as much as possible before and after maintenance.

In the present invention, an optical waveguide is used as a method for equalizing the energy distribution of the beam spot on the irradiated surface. An optical waveguide is a circuit that has the capability of confining radiated light in a certain region and guiding and transmitting the energy flow parallel to the axis of the path.

The beam homogenizer disclosed in the present invention includes an optical waveguide in which two reflecting surfaces facing each other are formed, a laser beam is incident from one end surface, and the laser beam is emitted from the other end surface, and the other end surface is It is formed into a curved surface shape.

In the present invention, the reason why the end face on the laser beam exit side of the optical waveguide has a curvature is as follows. The present inventor considered that the laser beam is elongated in a rectangular shape by the optical system, and that the spread angle of the laser beam is remarkably increased, which is one of the causes of the non-uniform energy distribution. That is, it is estimated that the focal point of the lens that projects the laser beam emitted from the optical waveguide onto the irradiated surface is different between the center of the rectangular beam and both ends in the long side direction of the rectangular beam. did. Therefore, the end face on the laser beam exit side of the optical waveguide is curved so that the light beam elongated in the long side direction of the rectangular shape and the light beam reaching near the center of the rectangular shape are focused on the same irradiated surface. And the distance from the exit of the optical waveguide to the irradiated surface is made different between the both end portions of the rectangular beam spot and the vicinity of the center. Thereby, in the full length in the long side direction, the same irradiated surface becomes the focal position, and the energy distribution can be made uniform.

In other words, the curved surface shape of the end surface on the laser beam exit side in the beam homogenizer disclosed in the present invention is such that when the laser beam emitted from the optical waveguide is projected by the projection lens, the focal position of the center and end of the laser beam Is a curved surface shape that fits the irradiated surface.

Another configuration of the present invention is such that in the beam homogenizer, the optical waveguide that equalizes the energy distribution in the short side direction of the beam spot on the irradiated surface is replaced with a light pipe. The light pipe usually refers to a transparent member drawn out into a cone shape, a pyramid shape, a cylindrical shape, or the like that transmits light from one end to the other end by total reflection. In addition, you may use the reflection by a mirror for optical transmission.

The configuration of the laser irradiation apparatus disclosed in the present invention includes a laser oscillator, a beam homogenizer, and one or a plurality of cylindrical lenses for condensing the laser beam emitted from the beam homogenizer on the irradiated surface. The beam homogenizer includes an optical waveguide that has two reflecting surfaces facing each other, allows a laser beam to enter from one end surface, and emits the laser beam from the other end surface, and the other end surface has a curved shape. It is characterized by being molded.

In the configuration of the invention of the laser irradiation apparatus, the curved shape of the end surface on the laser beam emission side of the beam homogenizer is such that the laser beam emitted from the optical waveguide is projected at the center of the laser beam when projected by a projection lens. It is characterized by a curved surface shape so that the focal position of the end matches the irradiated surface.

In the above-described configuration of the laser irradiation apparatus, the laser oscillator is any one of an excimer laser, a YAG laser, a glass laser, a YVO ₄ laser, a YLF laser, and an Ar laser.

In another embodiment of the laser irradiation apparatus disclosed in the present invention, in the above-mentioned beam homogenizer, an optical waveguide that equalizes the energy distribution in the short side direction of the beam spot on the irradiated surface is replaced with a light pipe. is there.

The structure of the invention relating to the method for manufacturing a semiconductor device disclosed in the present invention includes a step of forming an amorphous semiconductor film on a substrate, a laser beam oscillated by a laser oscillator, and the amorphous semiconductor film as an irradiated surface. Forming a rectangular beam spot on the irradiated surface using a cylindrical lens array and a beam homogenizer, and laser annealing the amorphous semiconductor film while moving the position of the beam spot, The cylindrical lens array acts in the long side direction of the rectangular beam spot, the beam homogenizer acts in the short side direction of the rectangular beam spot, and two opposing reflecting surfaces are formed. An optical waveguide for allowing the laser beam to enter from the other end face and emitting the laser beam from the other end face. The method for manufacturing a semiconductor device energy distribution by the beam homogenizer being molded into a curved shape with a uniform laser beam, wherein the laser annealing the amorphous semiconductor film.

In the structure of the invention related to the method for manufacturing a semiconductor device, the laser oscillator is any one of an excimer laser, a YAG laser, a glass laser, a YVO ₄ laser, a YLF laser, and an Ar laser.

The structure of another invention of the semiconductor device manufacturing method disclosed in the present invention is such that, in the beam homogenizer, the light waveguide that equalizes the energy distribution in the short side direction of the beam spot on the irradiated surface is replaced with a light pipe. Is.

If a beam homogenizer that forms a rectangular beam spot using an optical waveguide disclosed by the present invention is used, a rectangular beam spot with a uniform energy distribution in the short side direction and a uniform energy distribution in the long side direction is irradiated. It can be formed on the surface. Further, since the position and energy distribution of the beam spot formed on the irradiated surface are less affected by the oscillation state of the laser oscillator, the beam stability can be improved.

When a rectangular beam spot emitted from a laser irradiation apparatus using an optical system disclosed by the present invention is scanned in the short side direction of a rectangular shape on a semiconductor film, a crystal due to nonuniformity of the energy distribution of the beam spot Generation of non-uniformity of the crystallinity can be suppressed, and the uniformity of crystallinity within the substrate surface can be improved. Further, according to the present invention, high stability as a laser irradiation apparatus can be ensured, and running costs can be reduced by improving maintainability. If the present invention is applied to a mass production line for low-temperature polysilicon TFTs, it is possible to efficiently produce TFTs with high operating characteristics.

First, a method for equalizing the energy distribution of the beam spot by the optical waveguide will be described with reference to FIG. First, the side view of FIG. An optical waveguide 602 having two reflecting surfaces 602a and 602b facing each other and an irradiated surface 603 are prepared, and light is incident from the left side of the paper. The light beam when the optical waveguide 602 exists is indicated by a solid line 601a, and the light beam when the optical waveguide 602 does not exist is indicated by a broken line 601b. When the optical waveguide 602 does not exist, the light beam incident from the left side of the drawing reaches the irradiated surfaces 603a, 603b, and 603c as indicated by the broken line 601b.

On the other hand, when the optical waveguide 602 exists, as indicated by the solid line 601a, the light rays are reflected by the reflection surface of the optical waveguide 602, and all the light rays reach the region of the irradiated surface 603b. That is, when the optical waveguide 602 exists, all the light rays that reach the areas of the irradiated surfaces 603a and 603c when the optical waveguide 602 does not exist reach the area of the irradiated surface 603b. Therefore, when a light beam is incident on the optical waveguide 602, reflection is repeated in the optical waveguide and reaches the exit. That is, it is superimposed on the irradiated surface 603b at the same position so that the incident light beam is folded. In this example, the combined length of the light spreads 603a, 603b, and 603c on the irradiated surface 603 when there is no optical waveguide is A, and the light spread on the irradiated surface 603 when there is an optical waveguide. When the length is B, A / B corresponds to the number of divisions of the homogenizer described in the prior art. In this way, by dividing the incident light beam and superimposing the divided light beams at the same position, the energy distribution of the light beam at the superimposed position is made uniform.

In general, the homogenizer has a higher uniformity of energy distribution at the position where the divided light beams are superimposed as the number of light beam divisions increases. In the optical waveguide 602, the number of light beams can be increased by increasing the number of reflections in the optical waveguide 602. That is, it is preferable to increase the length of the two reflecting surfaces of the optical waveguide in the light incident direction. Also, the number of divisions can be increased by reducing the interval between the reflecting surfaces facing each other. Alternatively, the number of divisions can be increased by increasing the NA (numerical aperture) of incident light.

A rectangular beam spot forming optical system disclosed in the present invention will be described with reference to FIG. First, the side view of FIG. 3B will be described. The laser beam emitted from the laser oscillator 131 is propagated in the direction of the arrow in FIG. First, the laser beam is expanded by the spherical lenses 132a and 132b. This configuration is not necessary when the beam spot emitted from the laser oscillator 131 is sufficiently large.

The laser beam is focused in the short side direction of the rectangle by the cylindrical lens 134 and is incident on an optical waveguide 135 having two opposing reflecting surfaces 135a and 135b disposed behind the cylindrical lens 134. A uniform surface with an energy distribution in the short side direction of the rectangular beam spot is formed on the exit surface of the optical waveguide 135.

As the length of the optical waveguide 135 in the incident direction is longer, and as the focal length of the cylindrical lens 134 is shorter, the energy distribution becomes more uniform. However, since the actual system must be manufactured in consideration of the size of the optical system, the length of the optical waveguide and the focal length must be practical according to the size of the system.

In FIG. 3, the uniform surface formed immediately after the optical waveguide 135 is projected onto the irradiated surface disposed behind the doublet cylindrical lens by the doublet cylindrical lens 136 disposed behind the optical waveguide 135. The doublet cylindrical lens is a lens composed of two cylindrical lenses 136a and 136b. Thereby, the uniform surface formed on the exit surface of the optical waveguide 135 can be projected onto another surface (irradiated surface). That is, the uniform surface and the irradiated surface 137 are in a conjugate position with respect to the doublet cylindrical lens 136. By the optical waveguide 135 and the doublet cylindrical lens 136, the energy distribution in the short side direction of the rectangular beam spot is made uniform, and the length in the short side direction is determined. Note that a singlet cylindrical lens may be used when the uniformity of the beam spot is not so required on the surface to be irradiated, or when the F value of the doublet cylindrical lens is very large.

Next, the top view of FIG. The laser beam emitted from the laser oscillator 131 is divided into a rectangular long side direction by a cylindrical lens array 133. The cylindrical lens array 133 is configured by arranging cylindrical lenses in the curvature direction. In the present embodiment, a cylindrical lens array in which five cylindrical lenses are arranged is used. Thereby, the energy distribution in the long side direction of the rectangular beam spot is made uniform, and the length in the long side direction is determined. A cylindrical lens that synthesizes the light beams divided by the cylindrical lens array may be disposed behind the cylindrical lens array.

The laser beam emitted from the cylindrical lens array 133 is incident on the optical waveguide 135 disposed behind. The end faces on the laser beam exit side of the two opposing reflecting surfaces 135a and 135b constituting the optical waveguide 135 have a curvature. The reason why the end face of the optical waveguide 135 on the emission side of the laser beam is curved will be described with reference to FIGS. In FIG. 2, a light beam 101 indicated by a solid line is a light beam that forms the vicinity of the center of the rectangular beam, and a light beam 102 indicated by a dotted line is a light beam that forms both end portions in the long side direction of the rectangular beam. A light beam emitted from the optical waveguide 103 having two reflecting surfaces facing each other forms a rectangular beam on the irradiated surface 105 by the projection lens 104. The light beam 102 is focused on the irradiated surface 105, while the light beam 101 is focused before the irradiated surface 105.

On the other hand, FIG. 1 shows the same configuration as the optical system shown in FIG. 2 except for the shape of the optical waveguide 113, and a light beam 112 elongated in the long side direction of the rectangular shape and a light beam 111 reaching near the center of the rectangular shape. The end surface on the light exit side of the optical waveguide 113 is a curved surface so as to focus on the same irradiation surface. The curved surface is a cylindrical surface with a curvature only in the long side direction.

With the configuration as shown in FIG. 1, it is possible to make a difference between the center and both ends of the light beam from the optical waveguide 113 having two reflecting surfaces facing each other in the long side direction of the rectangular shape. As a result, the focal position of the projection lens 114 on the irradiated surface 115 can be made the same at the center and both ends in the long side direction of the rectangular shape. Therefore, a rectangular beam spot having a uniform energy distribution over the entire length in the long side direction can be formed.

The advantage of using an optical waveguide is that the position of the uniform surface is completely fixed by the optical system. In other words, since a uniform surface is formed on the exit surface of the optical waveguide, the position of the uniform surface does not change at all even if the characteristics of the beam emitted from the laser oscillator is changed for each pulse or maintenance. In other words, it is not easily affected by pointing stability. This makes it possible to obtain a uniform beam on the irradiated surface that is not affected by changes in the state of the laser oscillator.

The laser oscillator combined with the beam homogenizer of the present invention preferably has a wavelength region that has a large output and is well absorbed by the semiconductor film. When a silicon film is used as the semiconductor film, the wavelength of the laser beam emitted from the laser oscillator to be used is preferably 600 nm or less in consideration of the absorption rate. Examples of the laser oscillator that emits such a laser beam include an excimer laser, a YAG laser (harmonic), and a glass laser (harmonic).

Further, although the present technology has not yet obtained a large output, as a laser oscillator that oscillates a laser beam having a wavelength suitable for crystallization of a silicon film, for example, a YVO ₄ laser (harmonic), a YLF laser (harmonic) ) Ar laser.

Hereinafter, a method for manufacturing the semiconductor device of the present invention using the beam homogenizer and the laser irradiation apparatus of the present invention will be described. First, a glass substrate is prepared as a substrate. As this substrate, a substrate having sufficient durability as long as the temperature is up to 600 ° C. is used. A silicon oxide film having a thickness of 200 nm is formed on the glass substrate as a base film. Further, an amorphous silicon film is formed thereon. Both films are formed by sputtering. Or you may form into a film by plasma CVD method.

Next, the film-formed substrate is subjected to heat treatment in a nitrogen atmosphere. This step is a step for reducing the hydrogen concentration in the amorphous silicon film. If there is too much hydrogen in the film, the film cannot withstand the laser energy, so this step can be entered. The hydrogen concentration in the film is suitably on the order of 10 ²⁰ atoms / cm ³ . Here, 10 ²⁰ atoms / cm ³ means that 10 ²⁰ hydrogen atoms exist per 1 cm ³ .

In this embodiment, a XeCl excimer laser is used as the laser oscillator. The excimer laser is a pulse laser (oscillation wavelength is 308 nm). During the laser processing of one substrate, uniform crystallization can be performed when the energy fluctuation for each pulse of the pulse laser is within ± 5%, preferably within ± 2%.

The fluctuation of the laser energy described here is defined as follows. That is, the average value of the laser energy during the period during which one substrate is irradiated is used as a reference, and the difference between the minimum energy or the maximum energy during the period and the average value is expressed in%.

The laser beam irradiation is performed, for example, while scanning the stage on which the irradiated surface 137 shown in FIG. At this time, the practitioner may appropriately determine the energy density of the beam spot on the irradiated surface and the scanning speed. Rule of thumb is the range of the energy density of ^{200mJ / cm 2 ~1000mJ / cm 2} . If an appropriate scanning speed is selected in a range where the width of the rectangular beam spot in the short side direction is about 90% or more and overlaps each other, there is a high possibility that uniform laser annealing can be performed. The optimum scanning speed depends on the frequency of the laser oscillator and may be considered to be proportional to the frequency.

Thus, the laser annealing process is completed. A large number of substrates can be processed by repeating the above steps. By using the substrate, for example, an active matrix liquid crystal display, an organic EL display using an organic EL element as a light emitting element, and the like can be manufactured according to a known method.

In the above example, an excimer laser is used as the laser oscillator. An excimer laser has a very small coherence length of several μm and is suitable for the optical system in the above example. Some of the lasers shown below have a long coherent length, but a laser whose coherent length is intentionally changed may be used. Even if a harmonic of a YAG laser or a harmonic of a glass laser is used, the same large output can be obtained, and the energy of the laser beam is well absorbed by the silicon film, which is preferable. As a laser oscillator suitable for crystallization of a silicon film, there are a YVO ₄ laser (harmonic), a YLF laser (harmonic), an Ar laser, and the like. The wavelength range of these laser beams is well absorbed by the silicon film.

In the above example, an amorphous silicon film is used as the non-single crystal semiconductor film, but it can be easily estimated that the present invention can be applied to other non-single crystal semiconductors. For example, a compound semiconductor film having an amorphous structure such as an amorphous silicon germanium film may be used as the non-single-crystal semiconductor film. Alternatively, a polycrystalline silicon film may be used for the non-single-crystal semiconductor film.
[Comparative example]

This comparative example shows a typical method for manufacturing a semiconductor film to be irradiated with a laser beam. First, a Corning 1737 substrate having a thickness of 0.7 mm and a 127 mm square was prepared as a substrate. A SiO ₂ film (silicon oxide film) having a thickness of 200 nm is formed on the substrate using a plasma CVD apparatus, and an amorphous silicon film (hereinafter referred to as an a-Si film) having a thickness of 50 nm is formed on the surface of the SiO ₂ film. ) Was formed. The substrate was exposed to a nitrogen atmosphere at a temperature of 500 ° C. for 1 hour to reduce the hydrogen concentration in the film. An appropriate hydrogen concentration in the film is on the order of 10 ²⁰ atoms / cm ³ . Here, 10 ²⁰ atoms / cm ³ means that 10 ²⁰ hydrogen atoms exist per 1 cm ³ . This significantly improved the laser resistance of the film.

Next, an example of a laser specification suitable for laser annealing the a-Si film will be shown. As the laser oscillator, for example, use of a Lambda XeCl excimer laser (wavelength 308 nm, pulse width 30 ns) L4308 is preferable because sufficient output and throughput can be obtained. The laser oscillator emits a pulsed laser and has an ability to emit energy of 670 mJ per pulse. The spot size of the laser beam is approximately 10 × 30 mm (both half-value width) at the exit of the laser beam. The exit of the laser beam is defined by a plane perpendicular to the traveling direction of the laser beam immediately after the laser beam is emitted from the laser oscillator.

The shape of the laser beam generated by the excimer laser is generally rectangular and falls within the range of 1 to 5 when expressed in terms of aspect ratio. The intensity of the laser beam spot shows a Gaussian distribution that is stronger toward the center of the laser beam spot. The spot size of the laser beam is converted into a linear beam spot having a uniform spot shape of 125 mm × 0.4 mm by the optical system shown in FIG.

According to the experiment by the present inventors, when the above-mentioned semiconductor film is irradiated with a laser beam, the overlay pitch is most suitable around 1/10 of the short width (half width) of the linear beam spot. Thereby, the uniformity of crystallinity in the semiconductor film was improved. In the above example, since the half width was 0.4 mm, the pulse frequency of the excimer laser was 30 Hz, the scanning speed was 1.0 mm / s, and the laser beam was irradiated. At this time, the energy density on the surface irradiated with the laser beam was set to 450 mJ / cm ² . The method described so far is a very general method used for crystallizing a semiconductor film using a linear beam spot.

FIG. 4 shows an example of an optical system described in this embodiment. First, the side view of FIG. 4B will be described. The laser beam emitted from the laser oscillator 151 is propagated in the direction of the arrow in FIG. First, the laser beam is expanded by the spherical lenses 152a and 152b. This configuration is not necessary when the beam spot emitted from the laser oscillator 151 is sufficiently large.

A beam spot is narrowed in the short side direction of the rectangle by a cylindrical lens 155 having a curvature radius of −194.25 mm and a thickness of 20 mm on the second surface. The sign of the radius of curvature is positive when the center of curvature is on the light exit side with respect to the lens surface, and negative when the center of curvature is on the incident side with respect to the lens surface. In addition, the lens surface is a surface on which light is incident as a first surface and an exit surface as a second surface. The optical waveguide 156 having the two reflecting surfaces 156a and 156b facing each other arranged 428.8 mm behind the cylindrical lens 155 makes the energy distribution in the short side direction of the rectangular beam spot on the irradiated surface uniform. In this way, a uniform surface is formed at the exit of the optical waveguide 156. The optical waveguide 156 has a length of 300 mm in the light incident direction and a distance between the reflecting surfaces of 0.4 mm.

A rectangular short-side direction is formed on the irradiated surface 158 arranged 416.9 mm behind the doublet cylindrical lens 157 by a doublet cylindrical lens 157 (consisting of two cylindrical lenses 157a and 157b) arranged 400 mm behind the optical waveguide 156. The light beam emitted from the optical waveguide 156 is condensed. The doublet cylindrical lens refers to a lens composed of two cylindrical lenses. The two cylindrical lenses constituting the doublet cylindrical lens are one in which the first surface has a curvature radius of +122.99 mm, the second surface has a curvature radius of +90.12 mm, and a thickness of 10 mm. Each of the lenses is a cylindrical lens having a curvature radius of the first surface of +142.32 mm, a curvature radius of the second surface of −165.54 mm, and a thickness of 20 mm, and the interval between the two cylindrical lenses is 5 mm. Thereby, the uniform surface formed on the exit surface of the optical waveguide 156 can be projected onto the irradiated surface. By the optical waveguide 156 and the doublet cylindrical lens 157, the energy distribution in the short side direction of the rectangular beam spot is made uniform, and the length in the short side direction is determined.

Next, the top view of FIG. A laser beam emitted from the laser oscillator 151 is divided into spots in the long side direction of a rectangle by a cylindrical lens array 153. The cylindrical lens array 153 has a first surface with a radius of curvature of +24.5 mm, a thickness of 5 mm, and a width of 6.5 mm, in which five cylindrical lenses are arranged in the curvature direction.

Light beams divided by the cylindrical lens array 153 are superimposed on the irradiated surface 158 by a cylindrical lens 154 disposed 500 mm behind the cylindrical lens array 153. Thereby, the energy distribution in the long side direction of the rectangular beam spot is made uniform, and the length in the long side direction is determined. The cylindrical lens 154 is not used in the embodiment of the invention. By entering this lens, it is possible to reduce the energy attenuation portion generated at both ends in the long side direction of the rectangular beam spot. However, the focal length of the present lens may be remarkably increased due to the configuration of the apparatus. In such a case, the effect of the present lens may be reduced and may not be used.

The laser beam emitted from the cylindrical lens 154 enters an optical waveguide 156 disposed behind 1900.8 mm. A curvature of +3751.5 mm is given to the rear surfaces of the two reflecting surfaces 156a and 156b facing each other constituting the optical waveguide 156. Thereby, a difference can be provided in an incident position in the center and both ends part in a rectangular long side direction. Therefore, the center and both ends in the long side direction of the rectangular shape can be focused on the irradiated surface, and the rectangular shape (300 mm × 0.4 mm) in which the energy distribution is uniform over the entire length in the long side direction. A beam spot can be shaped.

Utilizing the optical system shown in this example, laser annealing of the semiconductor film is performed by the method according to the embodiment of the invention, for example. For example, an active matrix display or a light-emitting device can be manufactured using the semiconductor film. The production may be performed by a practitioner according to a known method.

In this example, an example of an optical system different from the optical system described in the embodiment is given. FIG. 5 shows an example of an optical system described in this embodiment.

In FIG. 5, the optical path other than the optical waveguide 165 passes through exactly the same optical path as the optical system shown in FIG. That is, the laser beam emitted from the laser oscillator 161 is expanded by the spherical lenses 162a and 162b, and the energy distribution in the long side direction is made uniform by the cylindrical lens array 163. Then, the beam spot is narrowed in the short side direction of the rectangle by the cylindrical lens 164 and is incident on the optical waveguide 165 arranged behind the cylindrical lens 164. Then, a doublet cylindrical lens 166 (consisting of cylindrical lenses 166a and 166b) disposed behind the optical waveguide 165 is formed immediately after the optical waveguide 135 on the irradiated surface 167 disposed behind the doublet cylindrical lens. The uniform surface is projected.

The optical waveguide 165 has two reflecting surfaces 165a and 165b facing each other in the same manner as the optical waveguide 135. The space between the two reflecting surfaces facing each other is hollow in the optical waveguide 135, while the space between the reflecting surfaces of the optical waveguide 165 is filled with a medium 165c having a refractive index n. They are different in this respect. If the refractive index n of the medium is larger than the refractive index of the material of the reflecting surface, when the light beam enters the optical waveguide 165 at an angle less than the critical angle, the light beam is totally reflected on the reflecting surface. That is, at this time, the light transmittance of the optical waveguide is higher than that in the case where the light is not totally reflected. Therefore, the light from the laser oscillator 161 which is a light source can be condensed on the irradiated surface 167 with higher efficiency.

With the optical system shown in FIG. 5, a rectangular beam spot having a uniform energy distribution with a length in the short side direction of 0.4 mm and a length in the long side direction of 300 mm can be formed. For example, it is preferable to use a HOYA BSC7 having a refractive index of 1.52 for ultraviolet light and a high transmittance.

Utilizing the optical system shown in this example, laser annealing of the semiconductor film is performed by the method according to the embodiment of the invention, for example. For example, an active matrix liquid crystal display or an organic EL display using an organic EL element as a light emitting element can be manufactured using the semiconductor film. The production may be performed by a practitioner according to a known method.

  In this embodiment, a process for manufacturing a crystalline semiconductor film by using the laser irradiation apparatus of the present invention and forming a semiconductor device will be described with reference to FIGS.

  First, base insulating films 1101 a and 1101 b are formed over the substrate 1100. Substrate materials include glass substrates, quartz substrates, crystalline glass and other insulating substrates, ceramic substrates, stainless steel substrates, metal substrates (tantalum, tungsten, molybdenum, etc.), semiconductor substrates, plastic substrates (polyimide, acrylic, polyethylene) Terephthalate, polycarbonate, polyarylate, polyethersulfone, etc.) can be used, but at least a material that can withstand the heat generated during the process is used. In this embodiment, a glass substrate is used.

  As the base insulating films 1101a and 1101b, a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or the like can be used. These insulating films are formed as a single layer or two or more layers. These are formed by using a known method such as a sputtering method, a low pressure CVD method, or a plasma CVD method. In this embodiment, a two-layer structure is used, but it is of course possible to use a single layer or a plurality of layers of three or more layers. In this embodiment, a silicon nitride oxide film is formed with a thickness of 50 nm as the first insulating film 1101a, and a silicon oxynitride film is formed with a thickness of 100 nm as the second insulating film 1101b. Note that the silicon nitride oxide film and the silicon oxynitride film have different ratios of nitrogen and oxygen, and the former indicates that the nitrogen content is higher.

Next, an amorphous semiconductor film is formed. The amorphous semiconductor film may be formed to a thickness of 25 to 80 nm using silicon or a material containing silicon as a main component (for example, Si _x Ge _{1 -x} ). As a manufacturing method, a known method such as a sputtering method, a low pressure CVD method, or a plasma CVD method can be used. In this embodiment, the film is formed with amorphous silicon to a film thickness of 66 nm.

  Subsequently, crystallization of amorphous silicon is performed. In this embodiment, a process of crystallizing by laser annealing will be described.

Laser annealing uses the laser irradiation apparatus of the present invention. As a laser oscillation device, an excimer laser, a YAG laser, a glass laser, a YVO ₄ laser, a YLF laser, an Ar laser, or the like may be used.

Amorphous silicon is crystallized by laser annealing using the laser irradiation apparatus of the present invention. More specifically, the method described in Example 1 and Example 2 may be performed. For example, the energy density may be 200 mJ / cm ^{2 to} 1000 mJ / cm ² and the number of shots may be 10 to 50 shots.

Next, the crystalline semiconductor film is etched into desired shapes 1102a to 1102d. Subsequently, a gate insulating film 1103 is formed. The thickness may be approximately 115 nm, and an insulating film containing silicon may be formed by a low pressure CVD method, a plasma CVD method, a sputtering method, or the like. In this embodiment, a silicon oxide film is formed. In this case, TEOS (Tetraethyl Ortho Silicate) and O ₂ are mixed by a plasma CVD method, and a high frequency (13.56 MHz) power density of 0.5 to 0.00 is obtained under a reaction pressure of 40 Pa and a substrate temperature of 300 to 400 ° C. It is formed by discharging at 8 W / cm ² . The silicon oxide film thus manufactured can obtain favorable characteristics as a gate insulating film by subsequent heat treatment at 400 to 500 ° C.

  By crystallizing the semiconductor film using the laser irradiation apparatus of the present invention, it is possible to suppress the crystallinity non-uniformity due to the non-uniformity of the energy distribution of the beam spot, and to have good and uniform characteristics. A crystalline semiconductor can be obtained.

  Next, tantalum nitride (TaN) with a thickness of 30 nm is formed as a first conductive layer over the gate insulating film, and tungsten (W) with a thickness of 370 nm is formed as a second conductive layer thereon. The TaN film and the W film may be formed by co-sputtering, the TaN film may be formed in a nitrogen atmosphere using a Ta target, and the W film may be formed using a W target. In order to use it as a gate electrode, it is required that the resistance is low. In particular, since the resistivity of the W film is desirably 20 μΩcm or less, it is desirable to use a high purity (99.99%) target for the W target. Also, attention must be paid to the contamination of impurities during film formation. The resistivity of the W film thus formed can be 9 to 20 μΩcm.

  In this example, the first conductive layer is TaN having a thickness of 30 nm and the second conductive layer is W having a thickness of 370 nm. However, the present invention is not limited to this, and the first conductive layer and the second conductive layer are Both may be formed of an element selected from Ta, W, Ti, Mo, Al, Cu, Cr, and Nd, or an alloy material or a compound material containing the 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. Furthermore, the combination may be selected as appropriate. The film thickness may be in the range of 20 to 100 nm for the first conductive layer and 100 to 400 nm for the second conductive layer. In this embodiment, a two-layer structure is used, but a single layer may be used, or a three-layer or more structure may be used.

  Next, in order to form the electrode and the wiring by etching the conductive layer, a mask made of a resist is formed through an exposure process by photolithography. In the first etching process, etching is performed under the first etching condition and the second etching condition. Etching is performed using a resist mask to form gate electrodes and wirings. Etching conditions may be selected as appropriate.

In this method, an ICP (Inductively Coupled Plasma) etching method was used. As the first etching condition, CF ₄ , Cl ₂ and O ₂ are used as etching gases, the respective gas flow rates are set to 25/25/10 (sccm), and 500 W RF is applied to the coil-type electrode at a pressure of 1.0 Pa. (13.56 MHz) Electric power is applied 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 the first etching condition so that the end portion of the first conductive layer is tapered. Under the first etching conditions, the etching rate for the W film is 200 nm / min, the etching rate for TaN is 80 nm / min, and the selection ratio of W to TaN is about 2.5. Further, the taper angle of the W film is about 26 ° under this first etching condition.

Subsequently, the etching is performed under the second etching condition. Without removing the resist mask, CF ₄ and Cl ₂ are used as etching gases while leaving the mask, and each gas flow rate is 30/30 (sccm), the pressure is 1.0 Pa, and the coil type electrode is 500 W. RF (13.56 MHz) power is applied to generate plasma, and etching is performed for about 15 seconds. 20 W RF (13.56 MHz) power is also applied to the substrate side (sample stage), and a substantially negative self-bias voltage is applied. Under the second etching condition in which CF ₄ and Cl ₂ are mixed, the W film and the TaN film are etched to the same extent.

  The etching rate for W under the second etching condition is 59 nm / min, and the etching rate for TaN is 66 nm / min. 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%. In this first etching process, the gate insulating film not covered with the electrode is etched by about 20 nm to 50 nm.

  In the first etching process, 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.

Next, a second etching process is performed without removing the resist mask. In the second etching process, SF ₆ , Cl _2, and O ₂ are used as etching gases, the respective gas flow rates are set to 24/12/24 (sccm), and the power on the coil side is 700 W at a pressure of 1.3 Pa. The RF (13.56 MHz) power is applied to generate plasma, and etching is performed for about 25 seconds. 10 W RF (13.56 MHz) power was also applied to the substrate side (sample stage), and a substantially negative self-bias voltage was applied. Under this etching condition, the W film was selectively etched to form a second shape conductive layer. At this time, the first conductive layer is hardly etched. A gate electrode including the first conductive layers 1104a to 1104d and the second conductive layers 1105a to 1105d is formed by the first and second etching processes.

Then, the first doping process is performed without removing the resist mask. Thereby, an impurity imparting N-type is added to the crystalline semiconductor layer at a low concentration. The first doping process may be performed by an ion doping method or an ion implantation method. The ion doping method may be performed at a dose of 1 × 10 ^{13 to} 5 × 10 ¹⁴ ions / cm ² and an acceleration voltage of 40 to 80 kV. In this embodiment, the acceleration voltage is 50 kV. As the impurity element imparting N-type, an element belonging to Group 15 can be used, and typically phosphorus (P) or arsenic (As) is used. In this example, phosphorus (P) was used. At that time, the first conductive layer as a mask, a first impurity region self-aligned manner low concentration impurity is added ^- to form a (N region).

Subsequently, the resist mask is removed. Then, a new mask made of resist is formed, and the second doping process is performed at a higher acceleration voltage than the first doping process. In the second doping process, an impurity imparting N-type is added. The conditions for the ion doping method may be that the dose is 1 × 10 ^{13 to} 3 × 10 ¹⁵ ions / cm ² and the acceleration voltage is 60 to 120 kV. In this embodiment, the dose is set to 3.0 × 10 ¹⁵ ions / cm ² and the acceleration voltage is set to 65 kV. In the second doping treatment, the second conductive layer is used as a mask for the impurity element, and doping is performed so that the impurity element is also added to the semiconductor layer located below the first conductive layer.

When the second doping is performed, a portion of the crystalline semiconductor layer that overlaps with the first conductive layer does not overlap with the second conductive layer or a portion that is not covered with the mask. Regions (N ⁻ region, Lov region) are formed. An impurity imparting N-type is added to the second impurity region in a concentration range of 1 × 10 ^{18 to} 5 × 10 ¹⁹ atoms / cm ³ . Further, in the crystalline semiconductor film, the exposed portion (third impurity region: N ⁺ region) which is not covered with the first shape conductive layer or the mask and is exposed to 1 × 10 ^{19 to} 5 Impurities imparting N-type are added at a high concentration in the range of × 10 ²¹ atoms / cm ³ . In addition, the semiconductor layer has an N ⁺ region, but there is a portion that is partially covered only by the mask. The concentration of impurity imparting N-type in this portion, since the remains of the impurity concentration added in the first doping process, subsequently the first impurity regions ^- is referred to as (N region).

  In this embodiment, each impurity region is formed by two doping processes, but the present invention is not limited to this, and a desired impurity concentration is obtained by performing doping once or a plurality of times by appropriately setting conditions. An impurity region may be formed.

Next, after removing the resist mask, a new resist mask is formed, and a third doping process is performed. A fourth impurity region (impurity element imparting a conductivity type opposite to the first conductivity type and the second conductivity type is added to the semiconductor layer to be a P-channel TFT by the third doping treatment ( P ⁺ region) and a fifth impurity region (P ⁻ region) are formed.

In the third doping process, a fourth impurity region (P ⁺ region) is formed in a portion that is not covered with the resist mask and does not overlap with the first conductive layer. A fifth impurity region (P ⁻ region) is formed in a portion that is not covered and overlaps with the first conductive layer and does not overlap with the second conductive layer. As the impurity element imparting P-type, elements of Group 13 of the periodic table such as boron (B), aluminum (Al), and gallium (Ga) are known.

In this embodiment, boron (B) is selected as the P-type impurity element for forming the fourth impurity region and the fifth impurity region, and is formed by ion doping using diborane (B ₂ H ₆ ). . As conditions for the ion doping method, the dose was 1 × 10 ¹⁶ ions / cm ² and the acceleration voltage was 80 kV.

  In the third doping process, the semiconductor layers A and C forming the N-channel TFT are covered with a resist mask.

Here, phosphorus is added to the fourth impurity region (P ⁺ region) and the fifth impurity region (P ⁻ region) at different concentrations by the first and second doping processes. However, in any of the fourth impurity region (P ⁺ region) and the fifth impurity region (P ⁻ region), the concentration of the impurity element imparting P-type is 1 × 10 5 by the third doping treatment. Doping treatment is performed so as to be ^{19 to} 5 × 10 ²¹ atoms / cm ³ . Therefore, the fourth impurity region (P ⁺ region) and the fifth impurity region (P ⁻ region) function without problems as the source region and the drain region of the P-channel TFT.

In this embodiment, the fourth impurity region (P ⁺ region) and the fifth impurity region (P ⁻ region) are formed by one third doping, but the present invention is not limited to this. The fourth impurity region (P ⁺ region) and the fifth impurity region (P ⁻ region) may be formed by a plurality of doping processes as appropriate depending on the conditions of the doping process.

By these doping treatments, the first impurity region (N ⁻ region) 1112b, the second impurity region (N ⁻ region, Lov region) 1111b, the third impurity region (N ⁺ region) 1111a, 1112a, the fourth Impurity regions (P ⁺ regions) 1113a and 1114a and fifth impurity regions (P ⁻ regions) 1113b and 1114b are formed.

Next, the resist mask is removed to form a first passivation film 1120. As this first passivation film, an insulating film containing silicon is formed to a thickness of 100 to 200 nm. As a film forming method, a plasma CVD method or a sputtering method may be used. In this embodiment, a silicon oxynitride film having a thickness of 100 nm is formed by plasma CVD. In the case of using a silicon oxynitride film, SiH _4, N ₂ O, a silicon oxynitride film formed from NH _3, or by SiH _4, N form a silicon oxynitride film formed from the ₂ O by plasma CVD It ’s fine. The production conditions in this case are a reaction pressure of 20 to 200 Pa, a substrate temperature of 300 to 400 ° C., and a high frequency (60 MHz) power density of 0.1 to 1.0 W / cm ² . Alternatively, a silicon oxynitride silicon film formed from SiH ₄ , N ₂ O, and H ₂ may be used as the first passivation film. Needless to say, the first passivation film 1120 is not limited to the single layer structure of the silicon oxynitride film as in this embodiment, and other insulating films containing silicon are used as a single layer structure or a stacked structure. Also good.

After that, laser annealing is performed using the laser irradiation apparatus of the present invention to recover the crystallinity of the semiconductor layer and activate the impurity element added to the semiconductor layer. For example, the energy density may be 100 mJ / cm ^{2 to} 1000 mJ / cm ² and the number of shots may be 10 to 50 shots. In addition to the laser annealing method, a heat treatment method or a rapid thermal annealing method (RTA method) can be applied.

  Further, by performing heat treatment after the first passivation film 1120 is formed, the semiconductor layer can be hydrogenated simultaneously with the activation treatment. In hydrogenation, dangling bonds in a semiconductor layer are terminated by hydrogen contained in the first passivation film.

  In addition, heat treatment may be performed before the first passivation film 1120 is formed. However, when the materials forming the first conductive layers 1104a to 1104d and the second conductive layers 1105a to 1105d are weak against heat, the first passivation film 1120 is used to protect the wiring and the like as in this embodiment. It is desirable to perform heat treatment after forming the film. Further, in this case, since there is no first passivation film, naturally hydrogenation using hydrogen contained in the passivation film cannot be performed.

  In this case, hydrogenation using means excited by plasma (plasma hydrogenation) or heat treatment at 300 to 450 ° C. for 1 to 12 hours in an atmosphere containing 3 to 100% hydrogen Hydrogenation by the method may be used.

  Next, a first interlayer insulating film 1121 is formed over the first passivation film 1120. An inorganic insulating film or an organic insulating film can be used as the first interlayer insulating film. As the inorganic insulating film, a silicon oxide film formed by a CVD method, a silicon oxide film applied by an SOG (Spin On Glass) method, or the like can be used. As an organic insulating film, polyimide, polyamide, BCB (benzoic acid) is used. A film such as cyclobutene), acrylic or positive photosensitive organic resin, or negative photosensitive organic resin can be used. Alternatively, a stacked structure of an acrylic film and a silicon oxynitride film may be used.

  The interlayer insulating film can be formed using a material having a skeleton structure of a bond of silicon (Si) and oxygen (O) and containing at least hydrogen as a substituent. Furthermore, it can be formed of a material having at least one of fluorine, alkyl group, and aromatic hydrocarbon as a substituent. Representative examples of these materials include siloxane polymers.

  Siloxane polymers can be classified according to their structures into, for example, silica glass, alkylsiloxane polymers, alkylsilsesquioxane polymers, hydrogenated silsesquioxane polymers, hydrogenated alkylsilsesquioxane polymers, and the like.

Alternatively, the interlayer insulating film may be formed using a material containing a polymer (polysilazane) having a Si—N bond.

  By using the above material, an interlayer insulating film having sufficient insulation and flatness can be obtained even when the film thickness is reduced. In addition, since the above material has high heat resistance, an interlayer insulating film that can withstand reflow processing in a multilayer wiring can be obtained. Further, since the hygroscopic property is low, an interlayer insulating film with a small amount of dehydration can be formed.

  In this embodiment, a non-photosensitive acrylic film having a thickness of 1.6 μm is formed. With the first interlayer insulating film, unevenness due to the TFT formed on the substrate can be relaxed and planarized. In particular, since the first interlayer insulating film has a strong meaning of flattening, it is preferable to use an insulating film made of a material that is easily flattened.

  Thereafter, a second passivation film (not shown) made of a silicon nitride oxide film or the like is formed on the first interlayer insulating film. The film thickness may be about 10 to 200 nm, and the second passivation film can prevent moisture from entering and exiting the first interlayer insulating film. In addition, a silicon nitride film, an aluminum nitride film, an aluminum oxynitride film, a diamond-like carbon (DLC) film, and a carbon nitride (CN) film can be used as the second passivation film.

A film formed using an RF sputtering method has high density and excellent barrier properties. For example, when a silicon oxynitride film is formed, RF sputtering is performed by flowing N ₂ , Ar, and N ₂ O at a gas flow ratio of 31: 5: 4 using a Si target and a pressure of 0.4 Pa. The film is formed with an electric power of 3000 W. Further, for example, when a silicon nitride film is formed, N ₂ and Ar in the chamber are flowed so that the gas flow ratio is 1: 1 with a Si target, the pressure is 0.8 Pa, the power is 3000 W, and the film formation temperature is set. The film is formed at 215 ° C. In this embodiment, a silicon oxynitride film is formed with a thickness of 70 nm by RF sputtering.

  Next, the second passivation film, the first interlayer insulating film, and the first passivation film are etched by etching to form contact holes that reach the third impurity region and the fourth impurity region.

  Subsequently, wirings and electrodes 1122 to 1128 that are electrically connected to the respective 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 (Al and Ti) having a thickness of 500 nm. Of course, it is not limited to a two-layer structure, and may be a single-layer structure or a laminated structure of three or more layers. Further, the wiring material is not limited to Al and Ti. For example, the wiring may be formed by forming an Al film or a Cu film on the TaN film and then patterning a laminated film formed with a Ti film.

  As described above, a semiconductor device manufactured using the laser irradiation apparatus of the present invention exhibits favorable and uniform characteristics, and thus can be suitably used for various electronic devices and particularly display devices. In addition, the reliability of the product is increased.

The figure explaining the means of this invention. The figure explaining the subject of this invention. The figure which shows the example of the laser irradiation apparatus which this invention discloses. The figure which shows the example of the laser irradiation apparatus which this invention discloses. The figure which shows the example of the laser irradiation apparatus which this invention discloses. The figure explaining equalization of energy distribution by an optical waveguide. The figure explaining a prior art. 4A and 4B illustrate a method for manufacturing a semiconductor device disclosed in the present invention. 4A and 4B illustrate a method for manufacturing a semiconductor device disclosed in the present invention.

Claims (34)

An optical waveguide having two reflecting surfaces facing each other, allowing a laser beam to enter from one end face, and emitting the laser beam from the other end face;
The beam homogenizer is characterized in that the other end surface is formed into a curved surface shape. An optical waveguide having two reflecting surfaces facing each other, allowing a laser beam to be incident from one end face, and shaping and emitting the laser beam into a rectangular laser beam from the other end face;
The beam homogenizer is characterized in that the other end surface is formed into a curved surface shape. 3. The curved surface shape according to claim 1 or 2, wherein the curved surface shape is such that when the laser beam emitted from the optical waveguide is projected by a projection lens, the focal position of the center and the end of the laser beam are aligned with the irradiated surface. A beam homogenizer characterized by 3. The curved surface according to claim 2, wherein when the laser beam emitted from the optical waveguide is projected by a projection lens, the focal positions of the center and the end in the long side direction of the rectangular laser beam match the irradiated surface. A beam homogenizer characterized by a curved shape. 5. The beam homogenizer according to claim 2, wherein an energy distribution in a short side direction of the rectangular laser beam is made uniform. 6. The beam homogenizer according to claim 2, wherein the rectangular aspect ratio is 10 or more. 6. The beam homogenizer according to claim 2, wherein the rectangular aspect ratio is 100 or more. A light pipe having two reflecting surfaces facing each other, allowing a laser beam to be incident from one end face, and emitting the laser beam from the other end face;
The beam homogenizer is characterized in that the other end surface is formed into a curved surface shape. A light pipe having two reflecting surfaces facing each other, allowing a laser beam to be incident from one end face, and shaping and emitting the laser beam into a rectangular laser beam from the other end face;
The beam homogenizer is characterized in that the other end surface is formed into a curved surface shape. 10. The curved surface shape according to claim 8, wherein the curved surface shape is formed so that a focal position of a center and an end of the laser beam is aligned with an irradiated surface when the laser beam emitted from the light pipe is projected by a projection lens. A beam homogenizer characterized by 10. The curved surface according to claim 9, wherein when the laser beam emitted from the light pipe is projected by a projection lens, the focal positions of the center and the end in the long side direction of the rectangular laser beam match the irradiated surface. A beam homogenizer characterized by a curved shape. 12. The beam homogenizer according to claim 9 or 11, wherein an energy distribution in a short side direction of the rectangular laser beam is uniformized. The beam homogenizer according to any one of claims 9 to 12, wherein the rectangular aspect ratio is 10 or more. The beam homogenizer according to any one of claims 9 to 12, wherein the rectangular aspect ratio is 100 or more. A laser oscillator;
A beam homogenizer,
One or a plurality of cylindrical lenses for condensing the laser beam emitted from the beam homogenizer on the irradiated surface;
The beam homogenizer has two reflection surfaces facing each other, and includes an optical waveguide that allows a laser beam to be incident from one end face and to emit the laser beam from the other end face,
2. The laser irradiation apparatus according to claim 1, wherein the other end surface is formed into a curved surface shape. A laser oscillator;
Means for uniformizing the energy distribution in one direction of the laser beam emitted from the laser oscillator;
A beam homogenizer for homogenizing energy distribution in a direction orthogonal to the one direction of the laser beam;
One or a plurality of cylindrical lenses for condensing the laser beam emitted from the beam homogenizer in a direction orthogonal to the one direction on the irradiated surface;
The beam homogenizer has two reflection surfaces facing each other, and includes an optical waveguide that allows a laser beam to be incident from one end face and to emit the laser beam from the other end face,
2. The laser irradiation apparatus according to claim 1, wherein the other end surface is formed into a curved surface shape. 17. The laser irradiation apparatus according to claim 16, wherein the means for uniformizing the energy distribution in one direction of the laser beam includes at least a cylindrical lens array. 18. The curved surface shape according to claim 15, wherein when the laser beam emitted from the optical waveguide is projected onto a surface to be irradiated by a projection lens, the focal positions of the center and end of the laser beam are as follows. A laser irradiation apparatus characterized by having a curved surface shape that fits the irradiated surface. A laser oscillator;
A beam homogenizer,
One or a plurality of cylindrical lenses for condensing the laser beam emitted from the beam homogenizer on the irradiated surface;
The beam homogenizer includes two light-reflecting surfaces facing each other, and includes a light pipe that allows a laser beam to enter from one end face and emits the laser beam from the other end face,
2. The laser irradiation apparatus according to claim 1, wherein the other end surface is formed into a curved surface shape. A laser oscillator;
Means for uniformizing the energy distribution in one direction of the laser beam emitted from the laser oscillator;
A beam homogenizer for homogenizing energy distribution in a direction orthogonal to the one direction of the laser beam;
One or a plurality of cylindrical lenses for condensing the laser beam emitted from the beam homogenizer in a direction orthogonal to the one direction on the irradiated surface;
The beam homogenizer includes two light-reflecting surfaces facing each other, and includes a light pipe that allows a laser beam to enter from one end face and emits the laser beam from the other end face,
2. The laser irradiation apparatus according to claim 1, wherein the other end surface is formed into a curved surface shape. 21. The laser irradiation apparatus according to claim 20, wherein the means for uniformizing the energy distribution in one direction of the laser beam includes at least a cylindrical lens array. The curved surface shape according to any one of claims 19 to 21, wherein the curved surface has a focal position at a center and an end of the laser beam when the laser beam emitted from the light pipe is projected onto an irradiated surface by a projection lens. A laser irradiation apparatus characterized by having a curved surface shape that fits the irradiated surface. 23. The laser irradiation apparatus according to claim 15, wherein the laser beam has a rectangular shape. 24. The laser irradiation apparatus according to claim 23, wherein the beam homogenizer uniformizes an energy distribution in a short side direction of the laser beam. 25. The laser irradiation apparatus according to claim 23 or 24, wherein the rectangular aspect ratio is 10 or more. 25. The laser irradiation apparatus according to claim 23 or 24, wherein the rectangular aspect ratio is 100 or more. 25. The laser irradiation apparatus according to claim 15, wherein the laser oscillator is any one of an excimer laser, a YAG laser, a glass laser, a YVO ₄ laser, a YLF laser, and an Ar laser. . Forming an amorphous semiconductor film on the substrate;
A laser beam oscillated by a laser oscillator is shaped into a rectangular beam spot on the irradiated surface using a cylindrical lens array and a beam homogenizer with the amorphous semiconductor film as the irradiated surface, and the position of the beam spot Annealing the amorphous semiconductor film while moving
The cylindrical lens array acts in the long side direction of the rectangular beam spot, the beam homogenizer acts in the short side direction of the rectangular beam spot,
The beam homogenizer having two reflecting surfaces facing each other, including an optical waveguide that allows a laser beam to enter from one end surface and to emit the laser beam from the other end surface, and the other end surface is formed into a curved shape A method for manufacturing a semiconductor device, wherein the amorphous semiconductor film is laser-annealed using a laser beam whose energy distribution is uniformed by the step. 29. The curved surface according to claim 28, wherein when the laser beam emitted from the optical waveguide is projected onto the irradiated surface by a projection lens, the focal positions of the center and the end of the laser beam are aligned with the irradiated surface. A method for manufacturing a semiconductor device, which has a curved shape. Forming an amorphous semiconductor film on the substrate;
A laser beam oscillated by a laser oscillator is shaped into a rectangular beam spot on the irradiated surface using a cylindrical lens array and a beam homogenizer with the amorphous semiconductor film as the irradiated surface, and the position of the beam spot Annealing the amorphous semiconductor film while moving
The cylindrical lens array acts in the long side direction of the rectangular beam spot, the beam homogenizer acts in the short side direction of the rectangular beam spot,
The beam homogenizer having two reflecting surfaces facing each other, including a light pipe that allows a laser beam to enter from one end surface and to emit the laser beam from the other end surface, and the other end surface is formed into a curved shape A method for manufacturing a semiconductor device, wherein the amorphous semiconductor film is laser-annealed using a laser beam whose energy distribution is uniformed by the step. 32. The curved surface shape according to claim 30, wherein when the laser beam emitted from the light pipe is projected onto the irradiated surface by a projection lens, the focal positions of the center and the end of the laser beam are aligned with the irradiated surface. A method for manufacturing a semiconductor device, which has a curved shape. 32. The semiconductor device according to claim 28, wherein the laser beam oscillator is any one of an excimer laser, a YAG laser, a glass laser, a YVO ₄ laser, a YLF laser, and an Ar laser. Manufacturing method. 33. The method for manufacturing a semiconductor device according to claim 28, wherein the rectangular aspect ratio is 10 or more. 33. The method for manufacturing a semiconductor device according to claim 28, wherein the rectangular aspect ratio is 100 or more.

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