JP4503344B2 - Beam irradiation apparatus and method for manufacturing semiconductor device - 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.

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

  Therefore, in order to improve the characteristics of the polycrystalline TFT, the crystallization of the semiconductor film using a continuous wave laser beam is being studied. For example, an a-Si film is patterned on a glass substrate in a linear or island shape, and an a-Si film is crystallized by irradiating and scanning with an energy beam that is continuously output with respect to time from a continuous wave laser beam. There is a method to do (see Patent Document 1). According to Patent Document 1, it is described that the temperature of the glass substrate does not rise and the generation of cracks and the like is prevented by patterning a semiconductor thin film in a linear or island shape in advance. Further, in FIGS. 29 and 31 of Patent Document 1, only a necessary portion of the a-Si film is selectively crystallized by using a shielding plate provided with an opening without causing damage to the glass substrate or peeling of the film. It is described that.

Further, a galvanometer mirror (see Patent Document 2) and a polygon mirror (see Patent Document 3) are used as means for scanning (also referred to as deflection) laser light (also referred to as a laser beam). Galvano mirrors and polygon mirrors can easily increase the scanning speed. Therefore, the burden on the irradiation device can be reduced.
JP 2003-86505 A JP 2003-86507 A JP 2003-45890 A

  When the substrate is irradiated with the continuous wave laser beam as described above using a galvano mirror or a polygon mirror, the scanning width is limited. Therefore, it is necessary to repeat scanning of the laser light a plurality of times, and there is a region where the scanning of the laser light stops. Due to this stop region, uniform laser processing was difficult.

  Further, the speed of the laser beam scanned by scanning means such as a galvanometer mirror or a polygon mirror is not uniform at the center and end of the scanning width. For example, the laser beam reciprocated in the first direction by the galvanometer mirror decelerates toward the region where the reciprocating velocity changes direction (when the galvanometer mirror stops), and finally the velocity becomes zero. To accelerate. In such a region where the speed is decelerated and accelerated, and further becomes zero, the irradiation time becomes longer, and the irradiated object is irradiated with more energy than necessary. As a result, the present inventor has found that there is a risk of film peeling or the like in the amorphous semiconductor film. When film peeling occurs, there is a concern that a normal film may be roughened by the scattered semiconductor film. Thus, the nonuniformity of the scanning speed of the laser beam becomes a problem in the semiconductor field.

  On the other hand, in the polygon mirror, although the speed is not zero, the speed is not uniform at the center and the end of the scanning width. As a result, like the galvanometer mirror, there is a possibility that film peeling or the like occurs in the amorphous semiconductor film.

  As described above, there is room for improvement in performing uniform continuous wave laser beam irradiation. There were many points to be improved, especially when considering large substrates and mass production.

  Therefore, an object of the present invention is to solve the problem at the end of laser light irradiation when laser light irradiation is performed using a galvanometer mirror or a polygon mirror. In particular, it is an object of the present invention to provide a laser irradiation apparatus and a laser irradiation method for irradiating an object to be irradiated with uniform laser light in consideration of large substrates and mass production. Furthermore, it is possible to provide uniform laser treatment, that is, laser annealing (including crystallization and activation) for a thin film transistor (hereinafter referred to as TFT) using the laser irradiation apparatus and the laser irradiation method as described above. Let it be an issue.

  In view of the above problems, the present invention provides a spot (irradiation region) on an irradiated object of an energy beam (CW beam, particularly, CW laser when using a laser as a light source) that is continuously output. When scanning by reciprocating with a scanning means (deflection means) or the like, when the scanning speed (moving speed) of the spot is other than a predetermined value, that is, when it is not constant, the CW beam irradiated to the irradiated object is blocked ( Light-shield). In other words, the CW beam is blocked in a range where the scanning speed is other than a predetermined value, that is, a range where the scanning speed is not constant. The spot scanning speed (moving speed) other than a predetermined value is when the speed is not constant, for example, when it increases or decreases, and when it becomes zero. The areas where the speed is not constant but increase, decrease, or become zero are the scanning start position (one end) and the scanning end position (the other end). That is, the present invention is characterized in that the light shielding means is arranged in a range where the spot scanning speed is not constant.

  As the light shielding means, a light shielding plate may be used, and a configuration including a reflector that reflects the laser beam or an absorber that absorbs the laser beam can be employed. The shape of the light shielding plate can be set as appropriate, and it is sufficient that the range where the spot scanning speed is not constant does not hit the irradiated object. Further, since it is not necessary to fix the light shielding means, it is sufficient if the light shielding means can be shielded in synchronization with the scanning means, and a chopper may be used as the light shielding means.

  The scanning means is a mirror body (also called a mirror) that changes the incident position of the laser beam on the irradiation object, for example, means having one or a plurality of mirror bodies, means having a plurality of mirror bodies arranged in succession, Alternatively, other means having a mirror body can be used. Specific scanning means includes a galvanometer mirror and a polygon mirror. As another scanning unit, a mirror body having a flat surface or a curved surface on an axis may be fixed, and a mirror body rotating (including rotation or vibration) about the axis may be used. At this time, means for controlling the rotation of the mirror body is provided at one end or both ends of the shaft. Controlling the rotation means controlling the rotational speed in the case of rotation and the vibration width in the case of vibration. In consideration of the fact that when a plurality of mirror bodies are provided, the reflection state between the mirror bodies may be different, it is preferable that a single mirror body is provided.

  When a galvano mirror or a polygon mirror is used, the processing time can be shortened because the time required for acceleration / deceleration is short although the scanning speed is as high as 10 to several thousand mm / s. This is because galvanometer mirrors and polygon mirrors are lightweight and can perform high-speed scanning.

The apparatus for irradiating the continuously output energy beam (CW laser irradiation apparatus) may be a solid-state laser, such as a YVO ₄ laser, a YAG laser, a YLF laser, a YAlO ₃ laser, or an Ar laser. What is necessary is just to irradiate the energy beam continuously output using the beam inject | emitted from the said laser. The harmonics of these lasers can also be used.

  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). For example, 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.

  The irradiated object and the laser beam move relative to each other to process one row, and then the irradiated object and the laser beam move to start processing so that the next row can be processed. Such relative movement is repeated to process a large area. Therefore, the scanning speed of the laser beam and the scanning speed of the irradiated object are set so as to be synchronized with each other. That is, control is performed so that the first scanning unit that changes the traveling direction (scanning direction) of the laser beam and the second scanning unit that scans the irradiation object relative to the first scanning unit are synchronized. Good.

  Preferably, an fθ lens is disposed between the irradiation object and the scanning unit in order to make the spot shape of the laser beam constant. Further, it is preferable to use a telecentric fθ lens that can make the incident angle constant. Such an fθ lens has a limit in increasing its size, but can be processed over a wide area by moving the irradiation object and scanning.

  According to the present invention as described above, it is possible to irradiate the irradiated object only with a uniform region of the laser beam, that is, a region scanned at a constant speed, and a uniform laser beam irradiation method can be provided.

  Further, when a semiconductor film is used as an irradiation object, a polycrystalline TFT having uniform crystallinity and electrical characteristics can be provided. In the display device such as a liquid crystal display device having such a polycrystalline TFT, a light emitting device having a self-luminous element, and an integrated circuit circuit having a CPU and a memory, an effect such as uniform display or improved performance is expected. it can.

  By using the scanning means of the present invention in which the light shielding plate is arranged in a range where the scanning speed is not constant in the laser beam for scanning the irradiation object, uniform processing can be performed. As a result, peeling of the irradiated object, particularly the semiconductor film, can be prevented. The laser irradiation method of the present invention is suitable for laser annealing a semiconductor film formed on a large substrate.

  Embodiments of the present invention will be described below with reference to the drawings. However, the present invention can be implemented in many different modes, and those skilled in the art can easily understand that the modes and details can be variously changed 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 specific beam irradiation method and an irradiation apparatus (beam irradiation apparatus) for irradiating a beam will be described with reference to FIGS.

  First, as shown in FIG. 3 (A), a beam spot 31 is scanned onto an irradiation object 32 by a scanning means. First, the beam spot 31 is scanned in the first major axis direction (A1), then in the minor axis direction (B1), then in the second major axis direction (A2), and again in the minor axis direction (B1). ). By repeating such an operation, the beam spot 31 can be scanned over a wide range of the irradiated object. At this time, for example, scanning in the major axis direction is performed by the first scanning unit, and scanning in the minor axis direction is performed by the second scanning unit. The second scanning means corresponds to the movement of the irradiated object by a stage or the like.

  FIG. 3B illustrates a graph of the beam spot velocity. When combined with FIG. 3A, in the area where the speed of the beam spot decreases and increases, and in the short axis direction area, that is, in (C1), a slit, a shutter, etc. disposed between the object and the light source Thus, a cut-off region that is not irradiated with the CW beam is set. In the present embodiment, the light shielding plate 33 is disposed in the light shielding region. At this time, the distance between the irradiated object 32 and the light shielding plate 33 is preferably arranged close to suppress the influence of beam diffraction. Preferably, the distance between the irradiated object 32 and the light shielding plate 33 is 1 cm or less. Then, sequential scanning (zigzag scanning) is performed to irradiate the entire irradiated object with the beam.

  For example, if the beam spot size is 10 × 500 μm, the beam spot scanning speed is 500 mm / second, and the length of the irradiation area that can be irradiated with a single line is 100 mm, the beam spot is 0.2 seconds. Scan 100 mm. Thereafter, the object to be irradiated moves by the width of the irradiation region (in this embodiment, 200 μm in the minor axis direction). At this time, the light shielding region (non-irradiated region) is 5 mm from both ends of the non-irradiated object, and light shielding plates are provided at intervals of 90 mm. Therefore, when the beam spot is shielded, the irradiated object moves 200 μm in the minor axis direction by a stage or the like. By scanning as described above, the entire surface of the irradiation object having a large area can be processed uniformly.

  The light shielding plate may have a configuration including a reflector that reflects the beam, an absorber that absorbs the beam, and the like. The beam reflected from the reflector may be absorbed by a damper or the like. Furthermore, it is preferable to circulate cooling water for preventing heat generation in the damper. Moreover, as a material of the reflector used as a light shielding plate, it can form from metal materials, such as aluminum and stainless steel, or those alloys. Moreover, the absorber should just have black, and what is necessary is just to apply | coat black to these.

  The light shielding plate is disposed between the irradiated object and the first scanning unit in a range where the scanning speed of the beam on the irradiated object changes. This light shielding plate may be provided in the vicinity of the scanning means. Moreover, you may provide in the vicinity of a to-be-irradiated object. When the light shielding plate is provided in the vicinity of the scanning unit, the size of the light shielding plate can be reduced, and as a result, the irradiation apparatus can be reduced in size. Further, it is preferable to provide a light shielding plate in the vicinity of the object to be irradiated because the irradiation area can be accurately controlled and the influence of beam diffraction by the light shielding plate can be suppressed.

  Further, the arrangement of the light shielding plate is sufficient if a predetermined irradiation region can be formed, and the interval may be determined in consideration of the beam shape to be scanned and the irradiation region. When a galvanometer mirror is used as the first scanning means, the irradiation area of the beam to be scanned is about 5 to 30 cm. If the area to be shielded is, for example, about 0.5 to 2 cm at both ends, the distance between the light shielding plates is 1 to 29 cm. It becomes.

  In the present invention, the beam and the object to be irradiated may be moved relatively, and the beam may be moved, the object to be irradiated may be moved, or both may be moved. As a moving means for the irradiated object, a stage that moves along the XY axes may be used. For example, the moving means of the irradiated object is arranged such that a rail that moves in the X-axis direction and a rail that moves in the Y-axis direction cross each other, and the stage to which the irradiated object is fixed by suction or the like moves in the XY direction. . Alternatively, the irradiated object can be lifted by air or the like and moved in the XY directions. Further, when the irradiation area is moved in the minor axis direction, the movement of the stage is controlled so as to be synchronized with the beam scanning.

  In particular, when a polygon mirror is used as the scanning means, 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 it is considered that the beam reflection directions by the adjacent mirrors are different. For example, the practitioner assigns numbers to a plurality of mirrors and scans them once. At this time, it is preferable to grasp the characteristics of the movement of each mirror and set the control device for controlling the movement of the stage based on this.

  Further, it is preferable to irradiate the irradiated object (especially of a large area) with a beam efficiently by using a plurality of light sources or by splitting into a plurality of light sources. As a result, mass productivity is dramatically improved.

  In particular, when a multi-panel is manufactured from a large substrate, it is preferable to irradiate a beam so that an arbitrary panel is always inserted between light shielding plates arranged at both ends. By such irradiation, a semiconductor film that is uniformly crystallized over the entire surface of one panel can be formed. Therefore, there is no limitation on the region where the thin film transistor is provided, and the degree of freedom in design can be increased.

  Further, when the irradiated object is a semiconductor film formed on a substrate transparent to the beam, the beam may be incident obliquely. Interference caused by reflected light from the surface of the semiconductor film and reflected light from the back surface of the substrate due to oblique incidence can be prevented. Further, a damper or the like may be provided for processing the reflected light. The damper has a property of absorbing reflected light, and further has a structure in which cooling water is circulated in the damper in order to prevent the temperature of the partition wall from rising due to absorption of the reflected light.

  According to the present invention, it is possible to provide a processing method with high uniformity using a CW beam and an irradiation apparatus. Further, by using the irradiation apparatus and the processing method of the present invention for crystallization of a semiconductor film, a highly uniform crystalline semiconductor film, that is, a polycrystalline TFT can be provided.

(Embodiment 2)
In this embodiment mode, a laser irradiation apparatus and a laser irradiation method using a CW laser as one form of a beam will be described with reference to FIG. A case where a semiconductor film is used as the irradiation object and a galvano mirror is used as the first scanning means will be described.

  First, the CW laser emitted from the laser oscillator 101 is elongated by the optical system 102 and processed into a linear shape. Specifically, when a laser passes through a cylindrical lens or a convex lens included in the optical system 102, it can be processed into a linear shape.

  Thereafter, a laser processed into a linear shape (hereinafter referred to as a linear laser) is incident on the semiconductor film 106 through the galvanometer mirror 103 and the fθ lens 104. At this time, the linear laser is adjusted to form a laser beam spot 105 of a predetermined size on the semiconductor film. In addition, the fθ lens 104 makes the shape of the laser beam spot 105 constant on the surface of the irradiated object regardless of the angle of the galvanometer mirror.

  In FIG. 1, laser annealing is performed on a semiconductor film formed on a large-area substrate of 1500 mm (length in the Y direction in the drawing) × 1800 mm (length in the X direction in the drawing). The diameter of the fθ lens 104 is practically about 100 to 300 mm, that is, it can be scanned over a width of 100 to 300 mm.

  At this time, the vibration of the galvanometer mirror is controlled by a device (control device) 110 that controls the vibration of the galvanometer mirror. That is, it vibrates so that the angle of the mirror changes, and the laser beam spot 105 moves in one direction (for example, the X-axis direction in the figure). For example, when the galvanometer mirror vibrates in a half cycle, the laser beam moves by a certain width in the X-axis direction on the semiconductor film (outward path).

  Then, the semiconductor film moves in the Y axis direction by the XY stage 109. Similarly, the spot of the laser beam moves in the X-axis direction on the semiconductor film (return path) by the galvanometer mirror. Using the reciprocating motion of the laser beam, the spot of the laser beam moves along a path as indicated by reference numeral 107, and laser annealing is performed on the entire surface.

  The reciprocating direction is preferably perpendicular to the major axis direction of the laser beam spot (in the X-axis direction in the figure) because of high throughput. Alternatively, the major axis of the laser beam spot may be set to have a so-called oblique incidence having a certain angle with the reciprocating direction. That is, not only the vertical direction but also other directions may be set.

  During this reciprocating motion, when the galvano mirror 103 stops (including the moving region in the Y-axis direction), the speed of the laser beam spot is not constant but increases or decreases. Although there is a concern that the uniformity of the laser annealing is lost due to this, the present invention provides the light shielding plate 108 in a region where the speed of the laser beam spot is not constant, and blocks the irradiation of the laser beam to the region. Uniform laser annealing can be performed.

  At this time, the practitioner can appropriately set the shape of the light shielding plate. The light shielding means is not limited to the light shielding plate, and may be shielded in synchronization with the scanning means.

  The distance between the light-shielding plate and the semiconductor film is preferably arranged close in consideration of suppressing the influence of laser diffraction. In that case, the distance between the light shielding plate and the semiconductor film is preferably 1 cm or less.

  The interval between the light shielding plates may be set in accordance with the shape of the laser beam spot and the laser irradiation region determined by the fθ lens 104, for example, 3 to 30 cm. The width of the light shielding plate may be adjusted to the distance until the laser scanning speed becomes constant, and about 1 to 10 mm is sufficient for the galvanometer mirror. Moreover, you may provide the opening part of 3-30 cm in a plate-shaped light-shielding plate, or multiple. As a result, non-uniform laser annealing due to overlapping of laser beam spots scanned with one vibration can be prevented.

  The galvanometer mirror 103 performs a pendulum motion at a constant frequency, and as a result, the laser beam spot 105 performs a constant reciprocating motion. Then, the XY stage 109 moves by a predetermined length, and when the laser annealing for one row is finished, the XY stage 109 also moves in a rectangular shape so as to move to the next row.

  For example, while the galvanometer mirror 103 is vibrated, a range of 100 mm × 200 μm (a region of the laser irradiation region in the straight X-axis direction) is crystallized in the semiconductor film. Next, the semiconductor film 106 is moved in the Y-axis direction by 200 μm by the XY stage 109, and the laser beam is irradiated by the vibration of the galvano mirror 103. By this reciprocating motion, laser annealing can be performed uniformly over a range of 100 mm × 1500 mm. At this time, the interval between the light shielding plates is set to 100 mm. Similarly, other regions are irradiated with a laser beam, and laser annealing of the entire semiconductor film is performed. In the case of the present embodiment, by repeating the above-described process 18 times, the entire 1500 × 1800 mm semiconductor film can be laser-annealed.

  In general, the CW laser has high coherence. Therefore, the incident angle of the laser beam is set to 0 ° or more (oblique incidence), and the reflected light of the laser beam from the back surface of the irradiated object does not interfere with the reflected light of the laser beam from the surface of the irradiated object on the irradiated surface. It is preferable to do so.

  As described above, the present invention uses a CW laser, a first scanning unit such as a galvano mirror or a polygon mirror, a second scanning unit such as an XY stage, an fθ lens, and a light shielding plate. Even in the case of irradiating a large area as an irradiation object, laser annealing can be uniformly performed. As a result, mass productivity increases, leading to cost reduction of semiconductor device manufacturing.

  As described above, although the galvanometer mirror is used as the first scanning means in the present embodiment, a polygon mirror or a mirror having a mirror surface (preferably a single mirror surface) having a rotation function can be used.

  In the present invention, laser annealing, that is, laser treatment, may be performed after the semiconductor film is patterned into a desired shape, for example, an island shape, a line shape, or a panel shape.

(Embodiment 3)
In this embodiment, a case where a semiconductor film formed over a substrate is subjected to laser annealing using a plurality of laser oscillators, that is, laser treatment, so as to increase the mass productivity of thin film transistors is described.

  In FIG. 2, the laser oscillator 201, the telecentric fθ lens 204, the galvanometer mirror 203, and the pair of slits 207 are used, respectively, and laser annealing is performed on the semiconductor film 205 formed on a large area substrate of 1500 mm × 1800 mm. An example of 2A is a top view and FIG. 2B 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. Some film formation methods cannot withstand laser annealing because the hydrogen concentration in the semiconductor film is too high. Therefore, in order to increase the probability of withstanding laser annealing, it is preferable to set the hydrogen concentration in the semiconductor film 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. For the laser oscillator 201, for example, a second harmonic (wavelength: 532 nm) of an LD-pumped CW Nd: YVO ₄ laser is used. The output is 10 W and the TEM00 mode is used. The spot diameter of the laser beam 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 of the laser beam with respect to the semiconductor film 205 may be other than 0 °. At this time, the appropriate incident angle depends on the spot shape and size of the laser beam. For example, if the size of the laser 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, the appropriate incident angle θ is about 20 °. . At this time, the direction in which the spot 208 of the laser beam is stretched, that is, the major axis direction of the spot is the Y-axis direction in FIG. Depending on the purpose, it may be stretched in another direction, but in this embodiment, it may be stretched in the Y-axis direction in order to maximize the throughput.

  The optical system 202 processes the spot shape of a laser beam into a linear shape. 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 145 mm apart, and further, the focal point is placed 140 mm behind the plano-convex lens. A plano-convex cylindrical lens with a distance of 250 mm is arranged, and a plano-concave cylindrical lens with a focal length of 100 mm is arranged behind the plano-convex cylindrical lens and 145 mm. The direction of curvature of the plano-convex cylindrical lens and the plano-concave cylindrical lens are the same. Further, a galvano 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. In the present embodiment, 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 laser beam spot 208 linearly extended on the semiconductor film 205 is scanned on the semiconductor film 205 by the galvano mirror 203 at a speed of 500 mm / s. A slit 207 is provided as a light shielding plate at a position where the laser beam spot 208 accelerates or decelerates on the semiconductor film 205 to form a light shielding region so that the semiconductor film is irradiated only within a certain range of the scanning speed of the laser beam spot. At this time, the distance between the light shielding plates is set to 100 mm, and considering the prevention of diffraction of the laser beam, the distance between the light shielding plate and the semiconductor film is preferably 1 cm or less. Further, since the acceleration of the galvanometer mirror is sufficient to be several mm, the width of the light shielding plate may be about several mm. In the present embodiment, the width of the light shielding plate is 5 mm. That is, the range of 110 mm is scanned by the galvanometer mirror 203, and both ends thereof are cut by the slit 207 by 5 mm to form a light shielding region. Then, assuming that the width of the polycrystalline region formed by one scanning of the galvano mirror determined by the spot size (spot width in the Y-axis direction) is 200 μm, the spot 208 is scanned 110 mm in the X-axis direction by the galvano mirror, The XY stage 206 is moved by 200 μm in the Y direction, and the laser beam spot is again scanned on the semiconductor film 205 by the galvanometer mirror 203. These steps are repeated to laser anneal the A region in the figure. The A region can be formed by the number of laser oscillators, and these intervals are opened by 100 mm. 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 the B region is laser-annealed similarly to the A region. Through the series of operations, the entire surface of the semiconductor film 205 can be laser-annealed. Of course, there is no need to laser anneal the entire surface of the semiconductor film 205, and laser annealing may be performed only at a necessary position. As a result, the processing time can be 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 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. Thereby, a high throughput can be obtained as compared with the case where only one laser oscillator is used, and the configuration is particularly suitable for a large substrate.

  In this embodiment, an fθ telecentric lens is used to make the angle at which the laser beam is incident on the semiconductor film constant, but an fθ lens may be used instead.

  As described above, 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, by performing laser annealing using a plurality of laser oscillators, the mass productivity of thin film transistors 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, although the galvanometer mirror is used as the first scanning means in the present embodiment, a polygon mirror or a mirror having a mirror surface (preferably a single mirror surface) having a rotation function can be used.

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

  FIG. 4A shows a cross section of a light-emitting device, specifically, an EL module. FIG. 4B shows an enlarged view of a stacked structure of a light-emitting element (having an organic compound layer, a first conductive film, and a second conductive film) of an EL module.

  In FIG. 4A, a first substrate 400, a base insulating film 401, a TFT 422 having a semiconductor film formed by laser annealing using a laser irradiation apparatus of the present invention, a first conductive film (electrode) 403, insulation An object 404 (also referred to as a partition wall, bank, or bank), 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 semiconductor 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.

  Note that either the first conductive film or the second conductive film is formed of light-transmitting ITO or the like depending on whether light emitted from the organic compound layer is emitted upward or downward. In the case of emitting light to both, the first conductive film and the second conductive film may be light-transmitting conductive films.

  A TFT 422 (p-channel TFT) provided over the first substrate 400 is an element that controls current flowing in the organic compound layer 405, and includes an impurity region 411 that functions as a drain region (or a source region), a channel formation, and the like. A region 412 and a gate electrode 417 provided over the channel formation region are included. In addition, the drain electrode (or source electrode) 416 is connected to the first conductive film 403 and connected to the drain region (or source region). Further, a wiring 418 such as a power supply line or a source wiring is formed at the same time in the same process as the drain electrode 416.

  Over the first base material 400, a base insulating film 401 that is a base insulating film (here, a lower layer is a nitride insulating film and an upper layer is an oxide insulating film) is formed, and between the gate electrode 417 and the semiconductor film, A gate insulating film is provided. 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 TFT having a plurality of channels may be used.

  In this embodiment mode, the top gate TFT is described as an example. However, the present invention can be applied regardless of the TFT structure. For example, the present invention can be applied to a bottom gate type (reverse stagger type) TFT or a forward stagger type TFT. 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 using a vapor deposition 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. 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. 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.

  As shown in FIG. 4B, the organic compound layer (EL 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) and EIL (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.

In addition, in the case of full-color display as the organic compound layer (EL layer) 405, a material that emits red (R), green (G), and blue (B) light is deposited by an evaporation method using an evaporation mask or an inkjet. What is necessary is just to selectively form suitably according to the method. Note that the inkjet method is a method in which droplets (also referred to as dots) of a composition mixed with a material such as a conductive film or an insulating film are selectively ejected (ejected). 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). In addition, it is not limited to the laminated structure of the said organic compound layer.

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 and a color conversion layer for white light emitted upward may be provided after being provided over the second 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, an insulating film and a second conductive film are formed in this order on the color filter and the color conversion layer, and the drain electrode (or source electrode) 416 and the second conductive film are connected via a contact formed in the insulating film. Just connect.

  With the laser irradiation apparatus and the laser irradiation method of the present invention, a light-emitting device having a highly uniform crystalline semiconductor film can be provided. As a result, a light-emitting device in which unevenness of a laser beam due to display unevenness is reduced in the display portion can be provided.

  Note that the active matrix substrate of the present invention can also be used in liquid crystal display devices and other display devices, and also in 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. 5A 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. 5B 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. 5C 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. 5D illustrates a mobile 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. 5E illustrates an electronic book reader, which 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, it is possible to reduce the thickness and weight by using a flexible substrate as the insulating substrate of the active matrix substrate.

(Embodiment 6)
Note that the present invention is not limited to the CW beam, and the semiconductor film is formed by a laser beam even if it is an energy beam that is output in a pulsed manner (a pulse beam, particularly a pulse laser when a laser is used as a light source). If crystal grains continuously grown in the scanning direction can be obtained by oscillating laser light at an oscillation frequency that can be irradiated with the next laser light from melting to solidification, There is an effect. That is, a pulse beam in which the lower limit of the oscillation frequency is determined so that the period of pulse oscillation (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 significantly higher than a frequency of several tens to several hundreds Hz that is usually used is used.

  The reason why a high frequency is used will be explained. In a pulse laser, it is said that the time from when a semiconductor film is irradiated with laser light until the semiconductor film is completely solidified is several tens to several hundreds of nsec. By using, the next laser beam can be irradiated from when the semiconductor film is melted by the laser beam to solidification. 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. 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, Ar laser, Kr laser, excimer laser, CO ₂ laser, YAG laser, Y ₂ O ₃ laser, YVO ₄ laser, YLF laser, YAlO ₃ laser, glass laser can be used as the 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, YVO ₄ laser light having energy 2 W, TEM (00) oscillation mode, second harmonic (532 nm), oscillation frequency 80 MHz, pulse width 12 psec can be used as laser light, and pulse laser irradiation with this oscillator is performed. An apparatus can be used. Note that spots formed on the surface of the semiconductor film by processing laser light with an optical system can 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 almost no crystal grain boundaries in at least the TFT carrier movement direction, that is, the channel direction.

  That is, the present invention is characterized in that light is shielded when the scanning speed of the laser light spot is other than a predetermined value, regardless of whether scanning is performed using a beam oscillated continuously or in pulses. .

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. 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.

Claims (10)

Means for scanning an energy beam of a harmonic of a laser output with a pulse of 10 MHz or more on an object to be irradiated;
An f-θ lens for focusing the beam on the irradiated object downstream of the scanning means;
It means for shielding the front Symbol beam at the scanning start position and the scanning end position of said beam,
Have
The means for scanning is a galvanometer mirror or a polygon mirror,
The beam irradiation apparatus characterized in that a distance between the light shielding means and the irradiation object is 1 cm or less. According to claim 1, beam irradiation apparatus characterized by having a plurality of means for shielding the harmonic energy beam and the beam of the laser output by said pulse.   3. The beam irradiation apparatus according to claim 1, wherein the light shielding means is a light shielding plate having a reflector that reflects the beam or an absorber that absorbs the beam.   4. The beam irradiation apparatus according to claim 3, wherein the light shielding plate is provided with a rectangular opening.   5. The beam irradiation apparatus according to claim 4, wherein a length of the opening in a major axis direction is 3 to 30 cm. Means for scanning an energy beam of a harmonic of a laser output with a pulse of 10 MHz or more;
An f-θ lens downstream of the scanning means;
A method for manufacturing a semiconductor device for scanning with tie means for blocking, by focusing on the semiconductor film before Symbol beam at the scanning start position and the scanning end position of said beam,
The means for scanning is a galvanometer mirror or a polygon mirror,
A method for manufacturing a semiconductor device, wherein a distance between the light shielding means and the semiconductor film is 1 cm or less. In claim 6, a method for manufacturing a semiconductor device characterized by having a plurality of means for shielding the energy beam and the beam of laser harmonics output in the pulse. According to claim 6 or 7, wherein the means for shielding a method for manufacturing a semiconductor device, wherein the reflector for reflecting a beam, or a light shielding plate having an absorber which absorbs said beam. In claim 8, the method for manufacturing a semiconductor device characterized by rectangular opening is provided in the light shielding plate. The method for manufacturing a semiconductor device according to claim 9 , wherein a length of the opening in a major axis direction is 3 to 30 cm.

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