JP4515136B2 - Laser beam irradiation apparatus and method for manufacturing thin film transistor - Google Patents

Description

  The present invention relates to a beam irradiation apparatus and a beam irradiation method. Furthermore, the present invention relates to a method for manufacturing a thin film transistor using the apparatus and the method.

  In recent years, a thin film transistor (hereinafter referred to as a polycrystalline TFT) having a polycrystalline semiconductor film as a channel formation region has been studied as a semiconductor element included in a display device, an integrated circuit, or the like. With the development of display devices and integrated circuits, further improvements in the characteristics of polycrystalline TFTs are required.

  Therefore, as one means for obtaining a polycrystalline TFT, a semiconductor film is crystallized using a laser irradiation apparatus having a continuous wave laser and means for scanning a laser beam (also referred to as laser light) (for example, a patent) Reference 1).

  Further, a galvanometer mirror (see Patent Document 2) and a polygon mirror (see Patent Document 3) are often used as means for scanning with laser light. This is because it is easy to increase the scanning speed. Thereby, the burden of an apparatus can be reduced.

  FIG. 7 shows the structure of a conventional galvanometer mirror. The laser beam 72 emitted from the laser beam oscillator 71 is reflected by the galvanometer mirror 73 to form a spot (irradiation region) 75 on the irradiated object 74. When the galvanometer mirror 73 vibrates with the vibration width 76, the spot 75 scans the irradiated object, and laser irradiation processing is performed. The irradiated object is irradiated with laser light in accordance with the vibration width of the galvanometer mirror shown in FIG.

In the case of a polygon mirror, a plurality of mirrors provided in contact with each other rotate to irradiate the irradiated object with laser light.
JP 2003-86505 A JP 2003-86507 A JP 2003-45890 A

  In particular, when mass production with a large substrate is considered, it is important to efficiently obtain a uniform crystalline semiconductor film over a wide range. Therefore, a scanning means such as a galvano mirror or a polygon mirror, which is light in weight and can easily increase the scanning speed, has been well studied. Moreover, the burden of a laser irradiation apparatus can be reduced by these scanning means.

  However, when the scanning means as described above is used, there is a problem that the scanning speed and the irradiation state are not uniform at the end portions such as scanning start and scanning end on the laser irradiation surface. Further, when the galvanometer mirror is vibrated, the scanning width sometimes meanders.

  For example, when laser light is reflected on a galvanomirror that moves pendulum (vibrates) and the semiconductor film is irradiated with laser light, the point changes the direction of the pendulum movement (also referred to as the apex of the pendulum movement or when the galvanometer mirror stops). The speed slows down and finally goes to zero. After that, the speed is gradually accelerated by changing the direction of motion. Although the scanning speed of the galvanometer mirror is reduced and accelerated in a short time, such non-uniform laser irradiation, that is, irradiation unevenness becomes a problem as higher performance and uniform crystallization of the semiconductor film is required. I found out. The present inventor has found that there is a possibility that film peeling or the like may occur in the amorphous semiconductor film because the irradiation object is irradiated with energy more than necessary due to such irradiation unevenness. When film peeling occurs, there is a concern that a normal film may be roughened by the scattered semiconductor film. As described above, the non-uniform scanning speed of the laser beam becomes a problem in the semiconductor field where high performance and uniform crystallization of the semiconductor film is required.

  In addition, in the polygon mirror in which a plurality of mirrors that perform rotational movement are continuously connected, the irradiation position is slightly shifted depending on the incident angle of the laser beam reflected for each mirror. In particular, the deviation of the incident angle at the mirror boundary causes a deviation of the scanning start position and the scanning end position, which causes non-uniform laser irradiation processing. In addition, since the irradiation position is shifted in the direction perpendicular to the scanning direction, this also causes non-uniform laser irradiation processing. Such uneven irradiation of the laser beam becomes a problem in order to obtain higher performance and more uniform crystallinity of the semiconductor film.

  Therefore, an object of the present invention is to provide a beam irradiation apparatus and a beam irradiation method that make the scanning speed of a scanning unit such as a galvanometer mirror uniform or control the scanning position with high accuracy. It is another object of the present invention to provide uniform laser annealing (including crystallization and activation) for thin film transistors (hereinafter referred to as TFTs) using the beam irradiation apparatus and the beam irradiation method as described above. .

  In view of the above problems, the present invention is characterized in that when a scanning (deflecting) means having a single mirror body (also called a mirror) is used, the scanning means is rotated in one direction. Hereinafter, a galvano mirror will be described as an example of such a mirror body.

  Since the galvanometer mirror of the present invention is rotated in one direction, the rotation is stable, and the vibration of the mirror caused by the change in acceleration is eliminated. When the movement of the spot by the galvano mirror is taken as the X-axis direction, the irradiated object may be moved in the Y-axis direction perpendicular to the X-axis direction when the galvano mirror is at a position where the laser beam is not irradiated. Then, scanning can be performed in the XY axis directions, and laser irradiation processing can be performed on a large area. At this time, since the galvanometer mirror is rotated in one direction, the laser beam scans in only one direction on the X axis of the irradiated object.

  Specifically, as shown in FIG. 1, the mirror surface rotates around an axis installed on the galvano mirror 13. The shaft is provided with a support rod at one end or both ends, and a device for controlling rotation is provided. If there are support rods at both ends, the rotation axis is more stable and preferable. The laser beam 12 emitted from the oscillator 11 is reflected by the galvanometer mirror 13 to form a spot 15 on the irradiated object 14. As the galvano mirror 13 rotates, the spot moves and laser irradiation processing is performed on the irradiated object.

  Thus, by rotating the galvanometer mirror and utilizing inertia, the constant velocity of the spot on the irradiated surface is increased. Further, it is preferable to make the galvanometer mirror heavy because the inertia works more strongly, so that the constant velocity is improved. Further, the galvanometer mirror can take a simple and small configuration, and is preferable for mounting on a laser irradiation apparatus.

  Other scanning means includes scanning means having a plurality of mirror bodies (referred to as a polygon mirror for simplicity). As shown in FIG. 2, the polygon mirror of the present invention has a plurality of mirrors 27, and in order to provide a scanning time for the Y axis in accordance with the distance between the mirrors, the mirrors are not arranged in contact with each other. The laser beam 22 is incident on a polygon mirror 23 that rotates about an axis, and a spot 25 scans on the irradiated object 24. As a result, when the spot 25 is irradiated and when it is not irradiated appear alternately on the irradiated object 24. That is, no laser light is irradiated between the mirrors. By matching the timing when the laser beam is not irradiated and the movement of the irradiated object, the laser irradiation process can be performed efficiently. That is, the spot is scanned in the X-axis direction by the polygon mirror, and the irradiated object is moved in the Y-axis direction when the spot disappears (no laser light is irradiated). At this time, since the reflection direction of the laser beam is slightly different for each mirror of the polygon mirror, the amount of movement of the irradiated object in the Y-axis direction is changed for correction. As a result, it is not necessary to arrange a correction lens between the polygon mirror and the irradiation object, and the laser irradiation apparatus is simplified and preferable.

  By using the scanning means of the present invention, the irradiated object can be irradiated with uniform laser light. When a semiconductor film is used as the irradiated object, a polycrystalline TFT with uniform crystallinity and electrical characteristics can be obtained. Can be formed.

In the present invention, a continuously output energy beam (hereinafter referred to as a CW beam) can be used. As the CW beam, a solid laser may be used. For example, a beam emitted from a YVO ₄ laser, a YAG laser, a YLF laser, a YAlO ₃ laser, an Ar laser, or the like is applicable. These harmonics may also be used. Thus, when using a laser as a light source, it describes with CW laser.

  The laser beam may have an arbitrary shape, and is preferably processed so as to be linear by passing through the optical system. Note that “linear” here does not mean “line” in a strict sense, but means a rectangle (or oblong shape) with a large aspect ratio. For example, the aspect ratio is 10 or more (preferably 100 to 10,000). Specifically, the spot diameter of the linear laser beam is set to a major axis of 150 to 1000 μm and a minor axis of 5 to 20 μm. When a laser beam processed into a linear shape is used, processing with high throughput can be performed.

  As described above, the present invention can remove the nonuniformity of the laser beam irradiation caused by the operation of the scanning means and provide a polycrystalline TFT having uniform crystallinity and electrical characteristics. Furthermore, even for an object to be irradiated having a large area, a polycrystalline TFT with uniform characteristics can be formed over a wide range, and mass productivity of a display device or an integrated circuit can be improved.

  According to the present invention, a uniform laser irradiation can be performed on an object to be irradiated, and when a semiconductor film is used as the object to be irradiated, a polycrystalline TFT having uniform crystallinity and electric characteristics can be formed. In addition, the speed of the beam spot can be made constant on the irradiation object, or the spot scanning position is highly controllable, and uniform laser annealing can be performed on the semiconductor film. Furthermore, when a large substrate is used, it is suitable for the highly efficient laser annealing of the present invention.

  When the polygon mirror of the present invention is used, further uniform laser irradiation can be performed by setting the movement distance of the XY stage with each mirror.

  Embodiments of the present invention will be described below with reference to the drawings. However, it should be understood by those skilled in the art that the present invention can be implemented in many different modes, and that various changes in form and details can be made without departing from the spirit and scope of the present invention. Is done. Therefore, the present invention is not construed as being limited to the description of this embodiment mode. Note that in all the drawings for describing the embodiments, the same portions or portions having similar functions are denoted by the same reference numerals, and repetitive description thereof is omitted.

(Embodiment 1)
In this embodiment mode, a case is described in which a galvanometer mirror that rotates as a scanning unit and a semiconductor film is used as an irradiation object, and the semiconductor film is crystallized to form a polycrystalline TFT.

  3 shows an oscillator 101 that emits a CW laser (also referred to as a continuous wave laser), an optical system 102 that processes the shape of a laser beam emitted from the oscillator into a linear shape, and a laser that is processed into a linear shape. Galvano mirror for scanning the semiconductor film, axis 108 for rotating the galvano mirror, controller 110 for controlling the axis and controlling the rotation of the galvano mirror, the shape of the laser beam on the irradiated surface is constant 1 shows a laser irradiation apparatus having an fθ lens 104 for the purpose. The laser beam emitted from the oscillator is incident on an optical system, processed into a linear laser beam (hereinafter referred to as a linear beam), incident on a rotating galvanometer mirror, reflected by the galvanometer mirror, and an fθ lens. The irradiated object is irradiated through. The laser beam irradiation is controlled by the above function.

  For example, a plano-concave lens with a focal length of 50 mm and a plano-convex lens with a focal length of 200 mm are arranged in the optical system 102, and a plano-convex cylindrical lens with a focal length of 250 mm is arranged behind the plano-convex lens. A plano-concave cylindrical lens having a focal length of 100 mm is disposed behind. The direction of curvature of the plano-convex cylindrical lens and the plano-concave cylindrical lens are the same. By passing through such an optical system, the laser beam is repeatedly focused and the linear beam is processed. A lens other than the above-described lenses may be disposed, and the laser beam spot (also referred to as a beam spot) may be disposed on the irradiation surface so as to have a desired irradiation shape (for example, a linear shape).

  A control device 110 that controls the galvanometer mirror 103 to rotate in one direction is provided. A motor or the like can be used as means for rotating the galvanometer mirror. At this time, the weight of the galvanometer mirror may be increased in order to increase the constant speed of rotation using inertia.

  The laser beam scanned by the galvanometer mirror passes through the fθ lens 104, is incident on the semiconductor film so that the shape of the laser beam on the semiconductor film is constant, and is scanned as indicated by the movement path 107. When the galvanometer mirror is rotated in one direction, the moving path 107 is only in one direction, and when the rotating direction is changed, the moving path 107 is opposite to the one direction.

  In such laser irradiation, when the semiconductor film is not irradiated with a laser beam, that is, when the beam spot 105 does not exist on the semiconductor film 106, the stage 109 moves in the Y-axis direction (arrow 112), and the scanning position of the spot 105 To change. By repeating this, laser irradiation processing, that is, laser annealing can be performed uniformly in the Y-axis direction. Next, when irradiating the adjacent semiconductor film, the irradiated object moves in the X-axis direction (arrow 111), and the same processing is performed. At this time, it is necessary to synchronize the scanning of the beam spot, that is, the rotation of the galvanometer mirror and the movement of the stage in the Y-axis direction.

  By the irradiation method as described above, the semiconductor film is not irradiated with a non-uniform range of the scanning speed of the laser beam, so that a polycrystalline TFT having further uniform crystallinity and electrical characteristics can be obtained.

  Thereafter, an active matrix substrate on which a plurality of polycrystalline TFTs are formed can be provided by appropriately performing the steps necessary to form the TFTs. At this time, when a polycrystalline TFT is formed using a large substrate, multiple surfaces can be obtained, and the manufacturing cost can be reduced. Note that the laser irradiation method of the present invention can be applied to laser annealing including crystallization and activation treatment of a semiconductor film.

(Embodiment 2)
In this embodiment, the case where a semiconductor film formed over a substrate is subjected to laser treatment using a plurality of laser oscillators to increase mass productivity of a thin film transistor will be described. The scanning means will be described using a polygon mirror.

  FIG. 4 shows an example in which laser annealing is performed on a semiconductor film 205 formed on a large area substrate of 1500 mm × 1800 mm using three CW laser oscillators 201, a telecentric fθ lens 204, and a polygon mirror 203. Show. 4A is a top view and FIG. 4B is a side view.

An oxide film (a silicon oxide film such as SiON or SiO ₂ ) and a semiconductor film are sequentially formed on the substrate as a base film. The semiconductor film may be formed using a material mainly containing silicon by a CVD method, a sputtering method, or the like. In this embodiment mode, an amorphous silicon film is formed by a CVD method using silane gas. Depending on the film formation method, the hydrogen concentration in the semiconductor film may be too high to withstand laser annealing. Therefore, in order to increase the probability of withstanding laser annealing, the hydrogen concentration in the semiconductor film is preferably set to the order of 10 ²⁰ / cm ³ or less. Therefore, when the hydrogen concentration is equal to or higher than the above value when the film formation is completed, it is preferable to perform a dehydrogenation process for about one hour by thermal annealing at about 400 to 500 ° C. Laser annealing is performed on the semiconductor film thus formed. Note that the semiconductor film may be patterned into a predetermined shape before laser annealing.

The laser oscillator 201 uses, for example, the second harmonic (wavelength 532 nm) of an LD-pumped continuous oscillation type Nd: YVO ₄ laser. The output is 10W and the TEM00 mode is used. The beam spot diameter is φ2.3 mm, and the spread angle is 0.35 mrad.

  In addition, since this wavelength shows translucency with respect to an amorphous silicon film or a substrate, it may be necessary to devise measures for suppressing non-uniformity of laser annealing due to interference. In that case, for example, the incident angle θ of the laser beam with respect to the semiconductor film 205 may be other than 0 °. At this time, an appropriate incident angle depends on the beam spot shape and size. The direction in which the beam spot 208 is extended (corresponding to the long axis) is the Y-axis direction in FIG. Although it may be stretched in other directions depending on the purpose, in this embodiment, the Y-axis direction is used in order to maximize the throughput. For example, in this embodiment, when the size of the beam spot on the semiconductor film 205 is a linear ellipse having a major axis of 400 μm and a minor axis of 20 μm, and the incident surface includes the major axis, an appropriate incident angle θ is 20 °. Degree.

  The optical system 202 processes the beam spot shape into a linear shape. For example, a plano-concave lens having a focal length of 50 mm and a plano-convex lens having a focal length of 200 mm are arranged 145 mm apart, and further, a focal length of 250 mm is provided 140 mm behind the plano-convex lens. And a plano-concave cylindrical lens having a focal length of 100 mm is arranged behind the plano-convex cylindrical lens at 145 mm. The direction of curvature of the plano-convex cylindrical lens and the plano-concave cylindrical lens are the same. Further, a polygon mirror 203 is arranged about 250 mm behind the plano-concave cylindrical lens, and the telecentric fθ lens 204 is arranged according to the specifications of these lenses. The focal length of the telecentric fθ lens 204 is about 300 mm and φ120 mm.

  In the laser irradiation apparatus having the optical system as described above, the beam spot 208 extended linearly on the semiconductor film 205 is scanned on the semiconductor film 205 at a speed of 500 mm / s by the polygon mirror 203. The polygon mirror of the present invention has time to change the scanning position on the semiconductor film because the boundary between the mirrors is not in contact.

  If the width of the laser beam irradiation area that can be scanned by one mirror of the polygon mirror is 100 mm, the polygon spot mirror scans the beam spot 208 100 mm in the X-axis direction, and then moves the XY stage 206 in the Y-axis direction. 200 μm (the width of the crystal perpendicular to the scanning direction of the laser beam determined by the beam spot size), and the polygon mirror 203 scans the beam spot on the semiconductor film 205 again.

  In particular, when a polygon mirror is used, it is preferable to finely adjust the moving distance of the stage for each mirror. This is because the polygon mirror has a plurality of mirrors, and the reflection angle at each mirror may be slightly different. Such a method will be described in detail in the third embodiment. In such laser irradiation, the region on the semiconductor film that is not irradiated with the laser beam differs depending on scanning means such as a polygon mirror and the laser beam, and may be set as appropriate for each implementation.

  By repeating the above, laser annealing is performed on the region A in the figure. The A region can be formed by the number of laser oscillators, but these intervals are appropriately set, for example, by 100 mm. Then, after the annealing of the A region is completed, the semiconductor film 205 is moved to a position where the B region can be laser-annealed by the XY stage 206, and similarly, the B region is laser-annealed with a constant width of 100 mm. Through the series of operations, the entire surface of the semiconductor film 205 can be laser-annealed. Of course, it is not necessary to laser anneal the entire surface of the semiconductor film 205, and it is preferable to perform laser annealing only at a required position because the processing time can be further shortened. In this case, it is necessary to make a positioning mechanism or the like precisely, but the configuration may be determined appropriately by the practitioner calculating the necessary accuracy.

  In this embodiment, an fθ telecentric lens is used in order to make the angle at which the laser beam is incident on the semiconductor film constant. Thereby, the uniformity of laser annealing can be obtained, but if not required, an fθ lens may be used instead. In the present embodiment, a plurality of telecentric fθ lenses 204 are arranged at intervals. Therefore, it is possible to simultaneously irradiate the semiconductor film with a plurality of laser beams without interference between adjacent telecentric fθ lenses.

  In this way, the semiconductor film is crystallized. Thereafter, the semiconductor film is patterned into a predetermined shape as necessary to form a gate insulating film, a gate electrode, and an impurity region, and activation is performed. The laser irradiation apparatus and method of the present invention can also be used to activate a semiconductor film. Then, an interlayer insulating film, a source wiring, a drain wiring, a pixel electrode, and the like are formed, and an active matrix substrate having a plurality of thin film transistors is formed. In addition, a liquid crystal display device, a light-emitting device, a display device having another display portion, a semiconductor integrated circuit, or the like can be formed using an active matrix substrate.

  As described above, a high throughput can be obtained as compared with the case where only one laser oscillator is used, and it is particularly suitable for laser annealing of a semiconductor film formed on a large substrate. As a result, mass productivity of the thin film transistor can be improved.

  Although a plurality of laser oscillators are used in this embodiment, a plurality of spots may be formed by dividing a laser beam from one laser oscillator by a mirror or the like.

  As described above, the polygon mirror is used as the scanning means in the present embodiment, but a galvanometer mirror having a rotation function can be used.

(Embodiment 3)
In the present embodiment, the movement timing of the polygon mirror and the XY stage will be described with reference to FIG. The polygon mirror has N mirrors (1 ≦ n ≦ N: n is an integer).

  In a scanning unit having a plurality of mirrors such as a polygon mirror, the reflection angle may be different for each mirror. In this situation, if the XY stage is moved at a constant interval, the scanning position interval is not constant, and uniform laser irradiation cannot be performed. Therefore, as in this embodiment, the distance between the mirrors of the polygon mirror, that is, the distance to move the XY stage when laser irradiation is not performed is set for each mirror, and more uniform laser irradiation is performed.

  That is, as shown in FIG. 8A, in an optical system that scans laser light 82 emitted from an oscillator 81 with a polygon mirror 83, the polygon mirror 83 rotates about an axis 85 and is formed by a mirror (n). Spot (n), spot (n + 1), spot (n + 1),... Are sequentially scanned in one direction in the X-axis direction, and laser irradiation processing is performed on the surface of the irradiation object 84. At this time, as shown in FIG. 8B, when the movement distance of the XY stage when moving from the mirror (n) to the next mirror is expressed as Y (n), Y (1), Y (2),. -It is more preferable to set Y (N) respectively. N represents the number of mirrors.

  As a method for setting the movement distances Y (n), Y (n + 1),... Of the XY stage, for example, a number is assigned to each of a plurality of mirrors, and scanning is performed once. Then, the reflection angle of each mirror is grasped, and the moving distance of the stage is determined based on this. What is necessary is just to input these each movement distance to the control apparatus of XY stage.

  As described above, when the movement distance and timing in the X-axis direction of the XY stage are set in accordance with the reflection angle and distance when the polygon mirror moves between the mirrors, more uniform laser irradiation processing can be performed.

  This embodiment can be applied even to a polygon mirror provided in contact with a mirror. That is, when the XY stage is moved at the boundary position of the mirrors provided in contact with each other, the movement distance of the XY stage is adjusted, and uniform laser irradiation becomes possible. Further, when it is desired to provide the stage moving time in the Y-axis direction, means for shielding light at both ends or one end (one end or the other end) of the laser beam scanning may be provided.

(Embodiment 4)
In this embodiment, a light-emitting device manufactured using an active matrix substrate will be described with reference to FIGS.

  FIG. 5A shows a cross section of a light-emitting device, specifically, an EL module. FIG. 5B shows an enlarged view of a stacked structure of light-emitting elements of an EL module (having an organic compound layer (also referred to as an EL layer), a first conductive film, and a second conductive film).

  FIG. 5A shows a first substrate 400, a base insulating film 401, a TFT 422 formed by laser annealing using the laser irradiation apparatus of the present invention, a first conductive film (electrode) 403, an insulator (a partition wall). , 404, an organic compound layer 405, a second conductive film (electrode) 406, a protective film 407, a gap 408, and a second substrate 409.

  As the first substrate and the second substrate, a glass substrate, a quartz substrate, a silicon substrate, a plastic substrate, a metal substrate, a stainless steel substrate, a flexible substrate, or the like can be used. A flexible substrate is a film-like substrate made of PET, PES, PEN, acrylic, or the like. If a light-emitting device is manufactured using a flexible substrate, weight reduction is expected. If a barrier layer such as an aluminum film (AlON, AlN, AlO, etc.), a carbon film (DLC, etc.), SiN or the like is formed on the surface of the flexible substrate or on the front and back surfaces, the durability and gas barrier This is desirable because of improved properties.

  Depending on whether light emitted from the organic compound layer is emitted upward or downward, either the first conductive film or the second conductive film is formed from a light-transmitting conductive film, such as ITO. . In the case of emitting light to both, the first conductive film and the second conductive film are formed as light-transmitting conductive films.

  A TFT 422 (a p-channel TFT in this embodiment mode) provided over the first substrate 400 is an element that controls current flowing in the organic compound layer 405 and functions as a drain region (a source region depending on polarity). An impurity region 411, a channel formation region 412, and a gate electrode 417 provided over the channel formation region. In addition, the drain electrode (or source electrode) 416 connected to the drain region (or source region) for electrically connecting the first conductive film 403 and the impurity region 411 is provided. In addition, a wiring 418 such as a power supply line or a source wiring can be formed at the same time in the same process as the drain electrode 416.

  A base insulating film (here, a nitride insulating film as a lower layer and an oxide insulating film as an upper layer) 401 is formed over the first substrate 400, and a gate insulating film is provided between the gate electrode 417 and the semiconductor film. It has been. The interlayer insulating film 402 is formed so as to have an organic material or an inorganic material. Although not shown here, one or more other TFTs (n-channel TFTs or p-channel TFTs) are provided in one pixel. Although a TFT having one channel formation region 412 is shown, the TFT is not particularly limited, and a so-called multi-channel TFT having a plurality of channels may be used.

  In addition, the top gate type TFT has been described as an example here, but the present invention can be applied regardless of the TFT structure, and is applied to, for example, a bottom gate type (reverse stagger type) TFT or a forward stagger type TFT. It is possible.

In addition, the first conductive film 403 serves as an anode (or a cathode) of the light emitting element. In the first conductive film, when using a transparent conductive film, ITO (indium tin oxide alloy), indium oxide-zinc oxide alloy (In ₂ O ₃ -ZnO), it can be used zinc oxide (ZnO) and the like.

  In addition, an insulator 404 (referred to as a bank, a partition, a barrier, a bank, or the like) is provided to cover an end portion (and the wiring 418) of the first conductive film 403. As the insulator 404, an inorganic material (silicon oxide, silicon nitride, silicon oxynitride, or the like), a photosensitive or non-photosensitive organic material (polyimide, acrylic, polyamide, polyimide amide, resist, or benzocyclobutene), or a material thereof Lamination etc. can be used. Note that in this embodiment mode, a photosensitive organic resin covered with a silicon nitride film is used. For example, when positive photosensitive acrylic is used as the organic resin material, it is preferable that only the upper end portion of the insulator has a curved surface having a curvature radius. As the insulator, either a negative type that becomes insoluble in an etchant by photosensitive light or a positive type that becomes soluble in an etchant by light can be used.

The organic compound layer 405 is formed by an evaporation method, an inkjet method, or a coating method. In this embodiment mode, the organic compound layer is formed with a vapor deposition apparatus to obtain a uniform film thickness. For example, when using an evaporation method, a vacuum degree of 5 × 10 ^-3 Torr (0.665Pa) or less, preferably vapor deposition is performed in the deposition chamber was evacuated to 10 ^-4 ~10 ^-6 Pa. At the time of vapor deposition, the organic compound is vaporized by heating in advance and is scattered in the direction of the substrate when the shutter is opened at the time of vapor deposition. The vaporized organic compound is scattered upward and deposited through an opening provided in the metal mask. In order to improve reliability, it is preferable to perform deaeration by performing vacuum heating (100 ° C. to 250 ° C.) immediately before the formation of the organic compound layer 405.

  As shown in FIG. 5B, the organic compound layer 405 includes, in order from the anode side, HIL (hole injection layer), HTL (hole transport layer), EML (light emitting layer), ETL (electron transport layer), EIL. The layers are stacked in the order of (electron injection layer). Typically, CuPc is used as HIL, α-NPD is used as HTL, BCP is used as ETL, and BCP: Li is used as EIL. Note that the organic compound may include an inorganic material or a mixed material of an organic material and an inorganic material.

In the case of full-color display as the organic compound layer 405, materials that emit red (R), green (G), and blue (B) light are appropriately selected by an evaporation method using an evaporation mask, an inkjet method, or the like. , Can be selectively formed. Specifically, CuPc or PEDOT is used as HIL, α-NPD is used as HTL, BCP or Alq _{3 is used} as ETL, and BCP: Li or CaF ₂ is used as EIL. Further, for example, EML may be Alq ₃ doped with a dopant corresponding to each emission color of R, G, and B (DCM in the case of R, DMQD in the case of G). The organic compound layer is not limited to a stacked structure, and may have a single layer structure.

More specifically, in the case of forming the organic compound layer 405 that emits red light, for example, after forming 30 nm of CuPc and 60 nm of α-NPD, using the same mask, Alq ₃ to which DCM ₂ and rubrene are added is formed to 40 nm as a red light emitting layer, BCP is formed to 40 nm as an electron transport layer, and BCP to which Li is added is formed 1 nm as an electron injection layer. When forming an organic compound layer that emits green light, for example, CuPc is formed to 30 nm, α-NPD is formed to 60 nm, and then coumarin 545T is added as a green light-emitting layer using the same vapor deposition mask. The formed Alq ₃ is formed to 40 nm, BCP is formed to 40 nm as an electron transport layer, and BCP doped with Li is formed to 1 nm as an electron injection layer. In the case of forming a layer containing an organic compound that emits blue light, for example, CuPc is formed to 30 nm and α-NPD is formed to 60 nm, and then the bis [2- (2- (2- Hydroxyphenyl) benzoxazolate] zinc: Zn (PBO) ₂ is formed to a thickness of 10 nm, BCP is formed to a thickness of 40 nm as an electron transport layer, and BCP doped with Li is formed to a thickness of 1 nm as an electron injection layer. As described above, among the organic compound layers of the respective colors, common CuPc and α-NPD can be formed on the entire surface of the pixel portion. The mask can also be shared by each color. For example, after forming the red organic compound layer, the mask can be shifted to form the green organic compound layer, and the mask can be shifted again to form the blue organic compound layer. . In addition, what is necessary is just to set the order of the organic compound layer of each color to form suitably.

  In the case of white light emission, full color display may be performed by separately providing a color filter, a color conversion layer, or the like. A color filter or a color conversion layer for white light emitted upward may be provided on the second substrate and then attached to the first substrate. Further, a color filter and a color conversion layer for white light emitted downward can be formed through an insulating film after the drain electrode (or source electrode) 416 is formed. After that, since the insulating film and the second conductive film are formed in this order on the color filter and the color conversion layer, the drain electrode (or source electrode) 416 and the second conductive film are connected via a contact formed in the insulating film. And connect.

  With the galvanometer mirror or polygon mirror of the present invention, a light-emitting device having a highly uniform crystalline semiconductor film can be provided. As a result, it is possible to provide a light-emitting device in which irradiation unevenness of the laser beam on the display portion (which causes display unevenness) is reduced.

  Note that the active matrix substrate of the present invention can also be used in liquid crystal display devices other than light-emitting devices, other display devices, semiconductor integrated circuits, and CPUs.

(Embodiment 5)
The active matrix substrate manufactured according to the present invention can be applied to various electronic devices. Examples of the electronic device include a portable information terminal (a mobile phone, a mobile computer, a portable game machine, an electronic book, etc.), a video camera, a digital camera, a goggle type display, a display display, a navigation system, and the like. Specific examples of these electronic devices are shown in FIGS.

  FIG. 6A illustrates a display, which includes a housing 4001, an audio output portion 4002, a display portion 4003, and the like. A display portion 4003 including a light-emitting element or a liquid crystal material can be completed using the active matrix substrate formed according to the present invention. The display device includes all information display devices such as a personal computer, a TV broadcast reception, and an advertisement display.

  FIG. 6B illustrates a mobile computer, which includes a main body 4101, a stylus 4102, a display portion 4103, operation buttons 4104, an external interface 4105, and the like. A display portion 4103 including a light emitting element and a liquid crystal material can be completed with the active matrix substrate formed according to the present invention.

  FIG. 6C illustrates a game machine, which includes a main body 4201, a display portion 4202, operation buttons 4203, and the like. A display portion 4202 including a light-emitting element and a liquid crystal material can be completed using the active matrix substrate formed according to the present invention. FIG. 6D illustrates a cellular phone, which includes a main body 4301, an audio output portion 4302, an audio input portion 4303, a display portion 4304, operation switches 4305, an antenna 4306, and the like. A display portion 4304 including a light-emitting element and a liquid crystal material can be completed using the active matrix substrate formed according to the present invention.

  FIG. 6E illustrates an electronic book reader that includes a display portion 4401 and the like. A display portion 4202 including a light-emitting element and a liquid crystal material can be completed using the active matrix substrate formed according to the present invention.

  As described above, the applicable range of the present invention is so wide that the present invention can be used for electronic devices in various fields. In particular, thin and light weight can be realized by using a flexible substrate as the insulating substrate of the active matrix substrate.

(Embodiment 6)
Note that the beam used in the present invention is not limited to a CW beam, and an energy beam (pulse beam, particularly expressed as a pulse laser when a laser is used as a light source) can be used.

  The pulse laser of the present invention continuously oscillates in the scanning direction by oscillating the laser beam at an oscillation frequency that can be irradiated with the next laser beam after the semiconductor film is melted and solidified by the laser beam. Control is performed so that grown crystal grains can be obtained. That is, it is possible to use a pulse beam in which the lower limit of the oscillation frequency is set so that the pulse oscillation period (oscillation frequency) is shorter than the time from when the semiconductor film is melted until it is completely solidified.

  For example, in a pulse laser using a laser as a light source, a specific oscillation frequency is set to 10 MHz or more, and a frequency band significantly higher than a frequency of several tens to several hundreds Hz that is normally used is used.

  It is said that the time from when the semiconductor film is irradiated with laser light until the semiconductor film is completely solidified is several tens to several hundreds nsec. By using such a high frequency, it is possible to irradiate the next pulse of laser light before the semiconductor film is melted by the laser light and solidified. Therefore, unlike the case of using a conventional pulse laser, the solid-liquid interface can be continuously moved in the semiconductor film, so that a semiconductor film having crystal grains continuously grown in the scanning direction is formed. . Specifically, a set of crystal grains having a width of 10 to 30 μm in the scanning direction of crystal grains and a width of about 1 to 5 μm in a direction perpendicular to the scanning direction can be formed. This is because crystal grains can be obtained. By forming single crystal crystal grains extending long along the scanning direction, it is possible to form a semiconductor film having almost no crystal grain boundaries in at least the TFT carrier movement direction.

If oscillation at the above-mentioned frequency is possible, an Ar laser, a Kr laser, an excimer laser, a CO ₂ laser, a YAG laser, a Y ₂ O ₃ laser, a YVO ₄ laser, a YLF laser, a YAlO ₃ laser, a glass laser can be used as a pulse beam. A beam emitted from a ruby laser, an alexandrite laser, a Ti: sapphire laser, a copper vapor laser, or a gold vapor laser can be used.

For example, a YVO ₄ laser having an energy of 2 W, an oscillation mode of TEM (00), a second harmonic (532 nm), an oscillation frequency of 80 MHz, and a pulse width of 12 psec can be used, and a pulse laser irradiation apparatus that oscillates this laser beam is used. be able to. Note that spots formed on the surface of the semiconductor film by processing laser light with an optical system have a rectangular shape with a short axis of 10 μm and a long axis of 100 μm. Since the solid-liquid interface can be continuously moved by setting the oscillation frequency to 80 MHz, crystal grains that are continuously grown in the scanning direction are formed. By forming single crystal grains extending in the scanning direction, it is possible to form a semiconductor film having few crystal grain boundaries at least in the channel direction of the TFT.

  That is, even when using either a continuous or pulsed laser beam, uniform laser irradiation can be performed by the galvanometer mirror or polygon mirror of the present invention.

The figure which shows the laser irradiation apparatus of this invention. The figure which shows the laser irradiation apparatus of this invention. The figure which shows the laser irradiation method of this invention. The figure which shows the laser irradiation method of this invention. FIG. 10 shows a light-emitting device formed using the laser irradiation method of the present invention. FIG. 13 illustrates an electronic device formed using the laser irradiation method of the present invention. The figure which shows the conventional laser irradiation method. The figure which shows the laser irradiation apparatus of this invention.

Claims (5)

An oscillator that outputs a continuous oscillation or a laser beam with an oscillation frequency of 10 MHz or more;
A galvanometer mirror fixed to an axis so as to be disposed on the optical axis of the laser beam, and rotating at a constant speed in one direction around the axis ;
And a stage for changing the scanning position of the beam spot when the irradiation object is not irradiated with the laser beam. In claim 1,
A laser beam irradiation apparatus comprising a plurality of the oscillator and the galvanometer mirror . An oscillator that outputs a continuous oscillation or a laser beam with an oscillation frequency of 10 MHz or more;
A polygon mirror that is fixed to an axis so as to be arranged on the optical axis of the laser beam, rotates at a constant speed in one direction around the axis, and does not arrange the mirrors in contact with each other;
A stage for correcting a beam spot scanning position by correcting a deviation of an irradiation position due to an incident angle of a laser beam reflected by each mirror of the polygon mirror when the irradiation object is not irradiated with a laser beam. A laser beam irradiation apparatus characterized by the above. In claim 3,
A laser beam irradiation apparatus comprising a plurality of the oscillator and the polygon mirror. The irradiated object is a semiconductor film used for a thin film transistor,
A method for manufacturing a thin film transistor, comprising: a step of irradiating the semiconductor film with a laser beam using the laser beam irradiation apparatus according to claim 1.

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