JP7781175B2 - Laser irradiation device, laser irradiation method, and display manufacturing method - Google Patents

Description

The present invention relates to a laser irradiation device, a laser irradiation method, and a display manufacturing method.

Patent Document 1 discloses a laser annealing device that uses an excimer laser. In this document, a levitation unit levitates a substrate, and a transport unit transports the substrate. A linear laser beam is then irradiated onto the substrate during transport.

JP 2018-64048 A

Such excimer laser light sources are expensive, making it difficult to reduce the component costs of the device. Therefore, it is desirable to use a light source other than an excimer laser light source. Semiconductor lasers are inexpensive, but they are continuous wave (CW) lasers. When CW laser light is pulsed using a modulator, the output decreases. Therefore, many light sources are required, making it difficult to reduce costs.

Other objects and novel features will become apparent from the description of this specification and the accompanying drawings.

According to one embodiment, the laser irradiation device is a laser irradiation device that irradiates laser light onto a film provided on a substrate, and includes a laser light source that generates laser light of a wavelength at least a portion of which is transmitted through the film, an optical system unit that guides the laser light to the substrate, and a levitation unit that has a through hole provided directly below the irradiation position of the laser light and levitates the substrate.

According to one embodiment, the laser irradiation device comprises a semiconductor laser light source that generates laser light having a wavelength of 500 nm or less, a transport unit that transports a substrate in a first direction, an optical system unit that guides the laser light, which is pulsed light, to the substrate, and a drive mechanism that drives the optical system unit to change the irradiation position of the laser light on the substrate in a second direction different from the first direction when viewed from above.

According to one embodiment, the laser irradiation device is a laser irradiation device that performs a dehydrogenation process on a film provided on a substrate, and is equipped with a semiconductor laser light source that generates laser light with a wavelength of 500 nm or less, an optical system unit that guides the laser light to the substrate, and a drive mechanism that changes the irradiation position of the laser light on the substrate.

According to one embodiment, the laser irradiation device includes a transport unit that moves a substrate having a film formed thereon in a first direction, a semiconductor laser light source that generates laser light with a wavelength of 500 nm or less, an optical system unit that guides the laser light to the substrate, a drive mechanism that changes the irradiation position of the laser light on the substrate in a second direction tilted from the first direction when viewed from above, an excimer laser light source that generates excimer laser light for crystallizing the film, and a crystallization optical system that guides the excimer laser light to the substrate being transported as a line beam whose longitudinal direction is tilted from the first direction when viewed from above.

According to one embodiment, the laser irradiation method is a laser irradiation method for irradiating a film provided on a substrate with laser light, and includes the steps of: (A1) levitating the substrate using a levitation unit having a through-hole provided directly below the irradiation position of the laser light; (A2) generating laser light of a wavelength at least a portion of which is transmitted through the film; and (A3) guiding the laser light to the levitated substrate using an optical system unit.

According to one embodiment, the laser irradiation method includes the steps of (B1) generating laser light having a wavelength of 500 nm or less using a semiconductor laser light source, (B2) transporting a substrate in a first direction using a transport unit, (B3) guiding the laser light, which is pulsed light, to the substrate using an optical system unit, and (B4) driving the optical system unit to change the irradiation position of the laser light on the substrate in a second direction different from the first direction when viewed from above.

According to one embodiment, the laser irradiation method is a laser irradiation method for performing a dehydrogenation treatment on a film provided on a substrate, and includes the steps of (C1) generating laser light having a wavelength of 500 nm or less using a semiconductor laser light source, (C2) guiding the laser light to the substrate using an optical system unit, and (C3) changing the irradiation position of the laser light on the substrate.

According to one embodiment, the laser irradiation method includes the steps of: (D1) transporting a substrate on which a film has been formed in a first direction using a transport unit; (D2) generating laser light having a wavelength of 500 nm or less using a semiconductor laser light source; (D3) guiding the laser light to the substrate using an optical system unit; (D4) changing the irradiation position of the laser light on the substrate to a second direction different from the first direction when viewed from above; (D5) generating excimer laser light for crystallizing the film using an excimer laser light source; and (D6) guiding the excimer laser light to the substrate during transportation as a line beam whose longitudinal direction is tilted from the first direction when viewed from above.

According to one embodiment, a method for manufacturing a display includes (S1) an irradiation step of irradiating a film formed on a substrate with laser light, and the (S1) irradiation step includes (SA1) a step of levitating the substrate using a levitation unit having a through-hole provided directly below the irradiation position of the laser light, (SA2) a step of generating laser light of a wavelength at least a portion of which is transmitted through the film, and (SA3) a step of guiding the laser light to the levitated substrate using an optical system unit.

According to one embodiment, a method for manufacturing a display comprises (S1) an irradiation step of irradiating a film formed on a substrate with laser light, the (S1) irradiation step comprising: (SB1) a step of generating laser light having a wavelength of 500 nm or less using a semiconductor laser light source; (SB2) a step of transporting the substrate in a first direction using a transport unit; (SB3) a step of guiding the laser light, which is pulsed light, to the substrate using an optical system unit; and (SB4) a step of driving the optical system unit to change the irradiation position of the laser light on the substrate in a second direction different from the first direction when viewed from above.

According to one embodiment, a method for manufacturing a display includes (T1) an irradiation step of irradiating a film formed on a substrate with laser light to perform a dehydrogenation treatment on the film, and the (T1) irradiation step includes (TC1) a step of generating laser light having a wavelength of 500 nm or less using a semiconductor laser light source, (TC2) a step of guiding the laser light to the substrate using an optical system unit, and (TC3) a step of changing the irradiation position of the laser light on the substrate.

According to one embodiment, a display manufacturing method includes (S1) an irradiation step of irradiating a film formed on a substrate with laser light, and the (S1) irradiation step includes (SD1) a step of transporting the substrate on which the film has been formed in a first direction by a transport unit; (SD2) a step of generating laser light having a wavelength of 500 nm or less by a semiconductor laser light source; (SD3) a step of guiding the laser light to the substrate by an optical system unit; (SD4) a step of changing the irradiation position of the laser light on the substrate to a second direction different from the first direction when viewed from above; (SD5) a step of generating excimer laser light by an excimer laser light source to crystallize the film; and (SD6) a step of guiding the excimer laser light to the substrate during transportation as a line beam whose longitudinal direction is tilted from the first direction when viewed from above.

According to the above embodiment, a highly productive laser irradiation device, laser irradiation method, and display manufacturing method can be provided.

1 is a top view schematically showing a laser irradiation device according to an embodiment; 1 is an XZ cross-sectional view schematically showing a laser irradiation device according to an embodiment; 1 is a YZ cross-sectional view schematically showing a laser irradiation device according to an embodiment; 1 is a table showing the penetration depth of silicon films. FIG. 10 is an XZ cross-sectional view schematically showing a laser irradiation device according to a modified example. FIG. 10 is a side view schematically showing a laser irradiation device according to a second embodiment. FIG. 2 is a top view schematically showing the spot shape of laser light. FIG. 10 is a top view schematically showing a laser irradiation device according to a third embodiment. FIG. 10 is a side view schematically showing a laser irradiation device according to a third embodiment. 1 is a photograph showing an annealed silicon film. 1 is a SIMS profile showing hydrogen concentration in an annealed silicon film. 1 is a cross-sectional view showing a simplified configuration of an organic EL display. 1A to 1C are cross-sectional views showing steps in a manufacturing method for a display according to the present embodiment. 1A to 1C are cross-sectional views showing steps in a manufacturing method for a display according to the present embodiment.

Embodiment 1.
The laser irradiation apparatus according to this embodiment performs an annealing process by irradiating a workpiece (also referred to as a workpiece) with laser light. The laser irradiation apparatus performs a dehydrogenation annealing process on a film provided on the substrate by heating the substrate with laser light. For example, the workpiece is a film-coated substrate on which a silicon film is formed. The laser irradiation apparatus uses a blue semiconductor laser light source as the laser light source. The laser irradiation apparatus performs a dehydrogenation process on the silicon film by irradiating the workpiece with blue laser light from the semiconductor laser light source. Note that the laser light is not limited to blue laser light, and can be laser light with a wavelength of 500 nm or less.

For example, in the manufacturing process of a display panel, a film forming device forms a film on a substrate. Then, a laser irradiation device irradiates the film with laser light. The substrate is, for example, a transparent substrate such as a glass substrate or a resin substrate, and the film is, for example, an amorphous silicon film. The substrate with the amorphous silicon film serves as the object to be processed. The laser irradiation device dehydrogenates the amorphous silicon film by irradiating it with laser light. Of course, the object to be processed may also be a substrate with a film formed thereon that is a film other than a silicon film. In the following description, the laser irradiation device is assumed to be a dehydrogenation annealing treatment device that uses laser light, but it may also be a crystallization annealing treatment device that crystallizes the amorphous silicon film by laser irradiation.

The configuration of the laser irradiation device according to this embodiment will be described using Figures 1 to 3. Figure 1 is a top view showing a schematic configuration of the laser irradiation device 1. Figure 2 is an XZ cross-sectional view showing a schematic configuration of the laser irradiation device 1. Figure 3 is a YZ cross-sectional view showing a schematic configuration of the laser irradiation device 1.

As shown in Figures 1 to 3, the laser irradiation device 1 comprises a levitation unit 10, a transport unit 11, an optical system unit 30, a Y drive mechanism 32, and a stage 40. The levitation unit 10 and the transport unit 11 constitute a transport device.

In the figures below, for ease of explanation, an XYZ three-dimensional Cartesian coordinate system is shown where appropriate. The Z direction is the vertical direction, perpendicular to the main surface of the workpiece 16. The X direction is the transport direction of the workpiece 16. The Y direction is the movement direction of the optical system unit 30. The laser light 15 is irradiated onto the workpiece 16 being transported in the X direction. Furthermore, the optical system unit 30 moves in the Y direction. Therefore, the irradiation position of the laser light on the workpiece 16 can be changed in the X and Y directions. This allows the laser light to be irradiated onto almost the entire surface of the workpiece 16.

As shown in FIG. 2, the levitation unit 10 is configured to eject gas from the surface of the levitation unit 10. The levitation unit 10 levitates the workpiece 16 on its upper surface. The gas ejected from the surface of the levitation unit 10 is sprayed onto the underside of the workpiece 16, causing the workpiece 16 to levitate. When the workpiece 16 is transported, the levitation unit 10 adjusts the amount of levitation so that the workpiece 16 does not come into contact with other mechanisms (not shown) located above the workpiece 16.

The levitation unit 10 is made of a porous material. For example, the levitation unit 10 is made of a ceramic material such as porous alumina or porous SiC. Here, the levitation unit 10 is a 10 mm thick porous material plate. The levitation unit 10 is connected to an air supply port (not shown). Therefore, gas from a gas supply means (not shown), such as a gas cylinder, is ejected from the top surface of the levitation unit 10.

The transport unit 11 transports the floating workpiece 16 in the transport direction. As shown in FIG. 1, the transport unit 11 includes a holding mechanism 12 and a moving mechanism 13. The holding mechanism 12 holds the workpiece 16. For example, the holding mechanism 12 can be configured using a vacuum suction mechanism. The vacuum suction mechanism is made of a metal material such as an aluminum alloy. Alternatively, the holding mechanism 12 may be made of a resin material such as PEEK (polyether ether ketone). The upper surface of the holding mechanism 12 has suction grooves, suction holes, etc. formed thereon. The holding mechanism 12 may also be made of a porous material.

The holding mechanism 12 (vacuum suction mechanism) is connected to an exhaust port (not shown), which is connected to an ejector, vacuum pump, etc. Therefore, a negative pressure is applied to the holding mechanism 12 to suck in gas, and the holding mechanism 12 can be used to hold the workpiece 16.

The holding mechanism 12 holds the workpiece 16 by sucking the surface (bottom surface) of the workpiece 16 opposite to the surface (top surface) irradiated with the laser light 15, i.e., the surface of the workpiece 16 facing the levitation unit 10. The holding mechanism 12 also holds the end of the workpiece 16 in the +Y direction.

The moving mechanism 13 provided in the transport unit 11 is connected to the holding mechanism 12. The moving mechanism 13 is configured to be able to move the holding mechanism 12 in the transport direction. The transport unit 11 (holding mechanism 12 and moving mechanism 13) is provided on the end side of the levitation unit 10 in the +Y direction, and the object 16 is transported by the moving mechanism 13 moving in the transport direction while the holding mechanism 12 holds the object 16.

As shown in Figure 1, for example, the moving mechanism 13 is configured to slide the +Y direction end of the levitation unit 10 along the transport direction. When the moving mechanism 13 slides the end of the levitation unit 10 along the transport direction, the workpiece 16 is transported along the transport direction.

The transport speed of the workpiece 16 can be controlled by controlling the movement speed of the movement mechanism 13. The movement mechanism 13 includes, for example, an actuator such as a motor (not shown), a linear guide mechanism, an air bearing, etc.

The workpiece 16 is a rectangular substrate with edges parallel to the X and Y directions. The workpiece 16 includes a substrate 16a and a film 16b formed on the substrate 16a. The substrate 16a is a transparent substrate such as a glass substrate. The film 16b is a silicon film such as an amorphous silicon film. By irradiating the film 16b with laser light 15 and performing an annealing process, the hydrogen contained in the film 16b can be removed. In other words, the laser irradiation device 1 serves as a dehydrogenation treatment device. While the film 16b is shown as a silicon film, other films may also be formed. For example, a thin film of copper or aluminum, which will serve as wiring, may be formed as an underlayer for the silicon film. Furthermore, an insulating film such as a silicon oxide film may be formed as an underlayer on the substrate 16a.

A stage 40 is positioned above the levitation unit 10. The stage 40 movably holds the optical system unit 30. The optical system unit 30 guides laser light from the laser light source 35 to the workpiece 16. The optical system unit 30 is positioned on the -X side of the stage 40. Therefore, the optical system unit 30 is positioned directly above the workpiece 16. Therefore, the laser light 15 from the optical system unit 30 is irradiated onto the workpiece 16 from above.

The stage 40 is a guide mechanism that guides the movement of the optical system unit 30 in the Y direction. For example, the stage 40 is provided with guide rails and guide grooves. The stage 40 is also provided with a Y drive mechanism 32. The stage 40 is a gantry stage that is installed along the Y direction in the space above the levitation unit 10. The Y drive mechanism 32 drives the optical system unit 30 in the Y direction.

The optical system unit 30 moves along the stage 40. As the optical system unit 30 moves in the Y direction, the irradiation position of the laser light 15 changes in the Y direction. On the +Y side and -Y side, the stage 40 is positioned so that it extends beyond the levitation unit 10. Therefore, in the Y direction, the optical system unit 30 can irradiate the laser light at any position on the workpiece 16.

Next, an example of a laser light source and its optical system will be described. The laser light source 35 generates laser light for annealing the workpiece 16. The laser light source 35 is a BLD (Blue Laser Diode) that generates blue laser light with a center wavelength of 450 nm. In other words, the laser light source 35 is a blue semiconductor laser light source. Here, the laser light is a continuous wave (CW) laser light. Of course, the laser irradiation device 1 may also modulate the laser light into pulsed laser light using a modulator or the like.

The laser light source 35 is coupled to an optical fiber 36. Laser light from the laser light source 35 enters the optical system unit 30 via the optical fiber 36. As shown in FIG. 2, the optical system unit 30 includes a lens 301, a mirror 302, and a lens 303. Of course, the optical system unit 30 may include optical elements other than the lens 301, the mirror 302, and the lens 303. Furthermore, the spot shape of the laser light 15 on the workpiece 16 is a line shape measuring 10 mm x 0.3 mm. The laser light 15 is CW light, and the irradiation time at one point on the workpiece 16 is 10 μsec to 1 sec.

Laser light from the optical fiber 36 enters the lens 301. The laser light focused by the lens 301 enters the mirror 302. The mirror 302 reflects the laser light toward the workpiece 16. Specifically, the mirror 302 reflects the laser light downward. The laser light reflected by the mirror 302 enters the lens 303.

Laser light 15 from lens 303 is irradiated onto the workpiece 16. Lens 303 focuses laser light 15 onto the workpiece 16. Therefore, laser light 15 from optical system unit 30 becomes a focused beam and is irradiated onto the workpiece 16. Optical system unit 30 irradiates laser light 15 onto the workpiece 16 from above. The film 16b on the workpiece 16 is annealed, and dehydrogenation treatment can be performed on the film 16b. Note that the optical axis of lens 303 is parallel to the Z direction, but it may be tilted from the Z direction.

Here, because the laser light source 35 is a blue semiconductor laser light source, the laser light 15 is blue laser light. For example, the center wavelength of the laser light 15 is 450 nm. Blue light has a deep penetration depth into silicon films. Therefore, not all of the laser light 15 is absorbed by the workpiece 16, and some of the laser light 15 passes through the workpiece 16.

If the laser light that passes through the workpiece 16 is absorbed by the levitation unit 10, the levitation unit 10 will be heated. As a result, the temperature of the levitation unit 10 will fluctuate during the process. Furthermore, because the laser light is reflected or scattered on the surface of the levitation unit 10, the laser light from directly below the irradiated area will re-enter the workpiece 16. This could result in the dehydrogenation annealing process becoming unstable.

In this embodiment, as shown in Figures 1 and 2, a through hole 10a is provided in the levitation unit 10 directly below the irradiation point of the laser light 15. When viewed from above, the through hole 10a is formed in a band-shaped area with the Y direction as the longitudinal direction. The laser light 15 passes through the through hole 10a and does not enter the levitation unit 10. This prevents the laser light 15 from being absorbed, reflected, or scattered by the levitation unit 10. In the X direction, the width of the through hole 10a is approximately 10 mm. In the Y direction, the length of the through hole 10a is approximately the same as the movable range of the optical system unit 30.

This allows the temperature of the levitation unit 10 to be stabilized. Furthermore, it is possible to prevent reflected or scattered light from the levitation unit 10 from being re-incident on the workpiece 16. It is possible to reduce reflected and scattered light from the surface of the levitation unit 10. This enables a stable dehydrogenation process and improves productivity.

In addition, in this embodiment, while the transport unit 11 is transporting the workpiece 16, the Y drive mechanism 32 drives the optical system unit 30. In other words, the Y drive mechanism 32 moves the irradiation position of the laser light in the Y direction, and the transport unit 11 moves the workpiece 16 in the X direction. Therefore, the irradiation position of the laser light on the workpiece 16 changes in the X and Y directions. This allows the laser light to be irradiated onto almost the entire surface of the workpiece 16. Therefore, almost the entire film 16b can be annealed, and the dehydrogenation process can be performed appropriately.

The movement speed of the optical system unit 30 in the Y direction may be faster than the transport speed in the X direction. This allows the laser irradiation position to be changed quickly in the Y direction. This prevents localized heating and therefore prevents any effects on the base film, etc.

In this embodiment, a blue laser diode is used as the laser light source 35, but the laser light source 35 is not limited to this. Specifically, when a film 16b of a predetermined thickness is provided on the substrate 16a, the laser light source 35 may be one that generates laser light of a wavelength that allows at least a portion of the laser light to pass through the film 16b.

Whether or not a wavelength is transmitted through film 16b depends on the material and thickness of the film. For example, if film 16b is an amorphous silicon film, the penetration depth (penetration depth) for light with a wavelength of 450 nm is 0.02 μm. Penetration depth is the thickness of a material when the amount of incident light entering the material is 1/e, where e is Napier's number. Penetration depth is determined by the extinction coefficient of the material. Furthermore, the extinction coefficient is wavelength-dependent. Penetration depth is determined by the material of the film and the wavelength of the light.

Figure 4 is a table showing the penetration depth of amorphous silicon (a-Si) films and single-crystal silicon (c-Si) films. Figure 4 shows the penetration depth for light with wavelengths of 308 nm, 355 nm, 450 nm, 532 nm, and 808 nm. The penetration depth is the film thickness at which the absorption rate becomes 1/e (63%). If film 16b is an amorphous silicon film and the laser wavelength is 450 nm, the penetration depth is 0.02 μm. In other words, when laser light with a wavelength of 450 nm is incident on an amorphous silicon film with a thickness of 0.02 μm, 36.8% is transmitted through the amorphous silicon film, and 1/e = 63% is absorbed by the amorphous silicon film.

If the film 16b has a thickness four times the penetration depth, 1.8% (= 1/ ^e4 ) of the laser light will transmit through the film 16b. Also, in the annealing process for dehydrogenation, if 1.8% of the laser light is incident on the levitation unit 10, the annealing process will be affected. Therefore, the laser irradiation device 1 according to this embodiment is suitable for annealing a film 16b having a thickness four times or less than the penetration depth. In other words, when annealing a film having a thickness four times or more than the penetration depth, the effect on the levitation unit 10 is negligible. If the film thickness of the film 16b is determined, the range of laser wavelengths suitable for this embodiment is determined.

Here, assume that film 16b is an amorphous silicon film with a thickness of 40 nm. As shown in the table in Figure 4, the penetration depth is 10 nm when the laser wavelength is 355 nm. When the laser wavelength is 355 nm or longer, 2% or more of the laser light passes through film 16b, affecting the process. For example, when using laser light with a wavelength of 355 nm or longer but 808 nm or shorter, 2% or more of the laser light passes through film 16b. Absorption, reflection, or scattering in the levitation unit 10 may cause process variations. Therefore, the laser irradiation device according to this embodiment is suitable for use with laser light with a wavelength of 355 nm or longer but 808 nm or shorter. In other words, it is suitable for annealing films with a thickness less than four times the penetration depth of the laser wavelength light.

In this embodiment, the optical system unit 30 may have an optical scanner for scanning the laser light. For example, the mirror 302 may be a galvanometer mirror. The optical scanner changes the irradiation position of the laser light by deflecting the laser light. Here, the optical scanner is a uniaxial optical scanner that changes the irradiation position of the laser light in the X direction. In other words, by changing the irradiation position in the X direction, the optical scanner can shorten the irradiation time during which the laser light is continuously irradiated to one point on the workpiece 16. This prevents localized heating of the base film, etc., thereby enabling a stable annealing process. When an optical scanner is used, the lens 303 may be an fθ lens. This allows the irradiation direction of the laser light to be parallel to the Z direction even when the optical scanner deflects the laser light.

The laser irradiation method according to this embodiment is a method for irradiating a film provided on a substrate with laser light. The laser irradiation method includes the steps of: levitating the substrate using a levitation unit having a through-hole provided directly below the irradiation position of the laser light; transporting the substrate levitated above the levitation unit in a first direction; generating laser light of a wavelength at least partially transmitted through the film; guiding the laser light to the substrate being transported using an optical system unit; and moving the optical system unit in a second direction so as to change the irradiation position of the laser light to a second direction different from the first direction when viewed from above. This can improve productivity.

(Variation 1)
The laser irradiation device 1 according to the first modification will be described with reference to Fig. 5. Fig. 5 is a side cross-sectional view schematically showing the configuration of the laser irradiation device 1. In the first modification, a damper 19 is added to the configuration of the first embodiment.

The damper 19 is positioned directly below the through-hole 10a. The damper 19 absorbs the laser light 15 that passes through the through-hole 10a. The damper 19 is a metal block with its longitudinal direction in the Y direction. It can be made to be approximately the same length as the through-hole 10a. For example, the damper 19 is made of a black-colored metal material. By providing the damper 19 to absorb the laser light 15, the laser light reflected or scattered around the through-hole 10a can be incident on the workpiece 16. This enables a more stable process.

In Figure 5, the damper 19 is placed directly below the through-hole 10a, but the placement location of the damper 19 is not limited to directly below the through-hole 10a. For example, a mirror that reflects blue laser light may be placed directly below the through-hole 10a. The damper 19 only needs to be placed in a position where it can absorb the laser light reflected by the mirror. In other words, the damper 19 absorbs the blue laser light reflected by the mirror.

The damper 19 may be cooled. For example, the damper 19 may be provided with a cooling mechanism such as an air-cooling mechanism or a water-cooling mechanism. Alternatively, the damper 19 may be provided with a heat dissipation mechanism. This can suppress temperature increases in the damper 19 and its surroundings, allowing the annealing process to be carried out stably.

Embodiment 2.
A laser irradiation apparatus according to a second embodiment will be described with reference to FIG. 6. FIG. 6 is a cross-sectional view schematically showing the configuration of a laser irradiation apparatus 1. In the second embodiment, the laser irradiation apparatus 1 is a laser crystallization apparatus for crystallizing an amorphous silicon film. Here, the film 16b before the laser light irradiation is an amorphous silicon film. The film 16b after the laser light irradiation is a polysilicon film. The laser light source 35 is a blue semiconductor laser light source. By irradiating the film 16b with blue laser light, the film 16b becomes a polysilicon film.

The laser irradiation device 1 is equipped with a modulator 306 and a beam shaping unit 307. The modulator 306 and the beam shaping unit 307 are mounted on the optical system unit 30. The configuration other than the modulator 306 and the beam shaping unit 307 is the same as in embodiment 1, so description thereof will be omitted.

The modulator 306 modulates the laser light. This modulates the CW laser light into pulsed laser light. Here, the repetition frequency R of the pulsed laser light is 10 kHz to 200 kHz. It is preferable that the irradiation time during which the laser light is continuously irradiated onto one location on the workpiece 16 be 1 μsec or less.

The pulsed laser light from the modulator 306 enters the beam shaping unit 307. The beam shaping unit 307 shapes the spot shape of the pulsed laser light. For example, the beam shaping unit 307 has a beam shaping mechanism such as a slit. Alternatively, if multiple optical fibers 36 are used, the beam may be shaped by arranging the output ends of the optical fibers 36. The beam shaping unit 307 shapes the beam so that the cross-sectional shape of the beam (spot shape) in a direction perpendicular to the optical axis is rectangular. For example, the spot shape is a rectangle with a longitudinal size of 10 mm and a lateral size of 0.03 mm. The spot shape of the beam on the object to be treated 16 will be described later.

The pulsed laser light shaped by the beam shaping unit 307 is incident on the workpiece 16 via lens 301, mirror 302, and lens 303, as in embodiment 1. The spot shape of the beam on the workpiece 16 is shown in Figure 7.

Figure 7 is an XY plane view that schematically shows the spot shape of the pulsed laser light on the workpiece 16. In the following explanation, it is assumed that the transport speed of the workpiece 16 by the transport unit 11 is sufficiently slower than the movement speed of the optical system unit 30 by the Y drive mechanism 32. Note that the sizes shown below are examples of this embodiment, and this embodiment is not limited to the sizes shown below.

The spot shape of the laser light 15 on the workpiece 16 is rectangular with a longitudinal direction. For example, the longitudinal size L of the spot shape is 900 μm, and the lateral size is 15 μm. The lateral and longitudinal directions are perpendicular to each other. The longitudinal direction is tilted from the X and Y directions. Specifically, the angle θ between the lateral and Y directions is 45°. In other words, the longitudinal direction of the spot shape is tilted 45° from the direction of movement of the optical system unit 30.

The movement speed V of the optical system unit 30 in the Y direction is 70.7 mm/s. The repetition frequency R of the pulsed laser light is 10 kHz. Therefore, the deviation amount P of the irradiation position per pulse in the Y direction is 7.07 μm/pulse. In other words, the irradiation positions (shot positions) of the two consecutive pulsed laser lights 15a and 15b are shifted by 7.07 μm in the Y direction.

The deviation D (= P × sin θ) of the irradiation position of the pulsed laser beams 15a and 15b in the longitudinal direction of the spot shape is 5 μm. The deviation H (= P × cos θ) of the irradiation position of the pulsed laser beams 15a and 15b in the lateral direction of the spot shape is 5 μm. Furthermore, S (= L × sin θ) is 318 μm.

By doing this, the number of times the beam end is repeatedly irradiated at the same location on the workpiece 16 can be reduced, thereby improving the uniformity of the crystallized film.

For example, in the beam cross-sectional profile, the light intensity at the ends of the beam is lower than at the center of the beam. In other words, the light intensity is highest at the center of the beam, and decreases as you move from the center to the ends of the beam. In this case, if the ends of the beam, which have low light intensity, are repeatedly irradiated, the surface roughness of the film 16b will differ from other areas. This will result in uneven display on the display.

Therefore, in this embodiment, the longitudinal direction of the beam cross section is tilted from the Y direction. In other words, the beam shaping unit 307 shapes the beam so that the longitudinal direction is an oblique direction tilted from the Y direction. This makes it possible to make the surface roughness uniform, thereby suppressing display unevenness. In other words, as the Y drive mechanism 32 moves the optical system unit 30 in the Y direction, the irradiation position of the laser light on the workpiece 16 changes in the longitudinal and lateral directions.

On the other hand, if the longitudinal direction is parallel to the Y direction, the irradiation position in the longitudinal direction does not change depending on the direction of movement of the optical system unit. Therefore, the end of the beam is irradiated at the same position multiple times.

In this way, in this embodiment, the beam shaping unit 307 shapes the cross-sectional shape of the beam so that the direction of the spot shape tilted from the X and Y directions is the longitudinal direction. This prevents the end of the laser light beam from repeatedly irradiating the same position on the workpiece 16. This makes uniform crystallization possible.

The laser irradiation method according to this embodiment includes the steps of generating blue laser light using a semiconductor laser light source, transporting a substrate in a first direction using a transport unit, guiding the laser light, which is pulsed light, to the substrate using an optical system unit, driving the optical system unit to change the irradiation position of the laser light on the substrate in a second direction different from the first direction when viewed from above, and shaping the laser light so that the longitudinal direction of the spot shape of the laser light on the substrate is tilted from the first and second directions when viewed from above. This improves productivity.

Embodiment 3.
In this embodiment, the laser irradiation apparatus 1 is an excimer laser anneal (ELA) apparatus that forms a low temperature polysilicon (LTPS) film. The laser irradiation apparatus 1 according to this embodiment will be described with reference to FIGS. 8 and 9. FIG. 8 is a top view that schematically shows the laser irradiation apparatus 1. FIG. 9 is an XZ cross-sectional view that schematically shows the configuration of the laser irradiation apparatus 1.

In this embodiment, the laser irradiation device 1 includes a laser light source 35, an optical system unit 30, a crystallization laser light source 51, and a crystallization optical system 52. Furthermore, the laser irradiation device 1 has multiple optical system units 30. In Figure 8, four optical system units are shown as optical system units 30a to 30d. Descriptions of content common to embodiments 1 and 2 will be omitted where appropriate.

The laser light source 35 is a blue semiconductor laser light source, as in embodiment 1. The blue laser light from the laser light source 35 is used to dehydrogenate the film 16b. The basic configuration of the optical system unit 30, stage 40, etc. is the same as in embodiment 1, so a description thereof will be omitted.

The crystallization laser light source 51 is a pulsed laser light source that generates pulsed laser light. The crystallization laser light source 51 is, for example, an excimer laser light source that emits excimer laser light with a center wavelength of 308 nm.

The excimer laser light from the crystallization laser light source 51 is incident on the crystallization optical system 52. The crystallization optical system 52 guides the laser light to the workpiece 16. The laser light irradiated from the crystallization optical system 52 onto the workpiece 16 is referred to as laser light 55. For example, the crystallization optical system 52 includes a projection lens for focusing the laser light 55 onto the workpiece 16. The crystallization optical system 52 can be similar to that used in known ELA devices, so a detailed description will be omitted.

The crystallization optical system 52 converts the laser light 55 into a line beam and irradiates it onto the workpiece 16. As shown in Figure 9, the Y direction is the longitudinal direction of the laser light 55 on the workpiece 16. The laser light 55 forms a linear illumination area on the workpiece 16. In other words, the laser light 55 focused on the workpiece 16 forms a linear irradiation area with the Y direction as the longitudinal direction (long axis direction) and the X direction as the lateral direction (short axis direction). Furthermore, while the transport unit 11 transports the workpiece 16 in the transport direction, the laser light 55 irradiates the film 16b. In this case, the transport direction is the X direction. This allows the laser light 55 to be irradiated onto a band-shaped area whose width is the length of the irradiation area in the Y direction.

Here, the transport direction of the transport unit 11 is the -X direction. The workpiece 16 being transported by the transport unit 11 is irradiated with laser light 15, and then irradiated with laser light 55. In other words, the area that has been dehydrogenated with laser light 15 is irradiated with laser light 55 for crystallization. Therefore, crystallization annealing can be performed immediately after dehydrogenation annealing with blue laser light.

This allows for a wider energy density (ED) margin in the ELA process. This means that a stable crystallization process is possible even when the energy density fluctuates. This makes it possible to improve the uniformity of the crystallized film.

A through-hole 10a is provided in the levitation unit 10 directly below the irradiation area of the laser light 55. Therefore, the laser light 55 passes through the through-hole 10a. Furthermore, as in variant example 1, a damper 19 is disposed below the through-hole 10a. Therefore, the laser light 55 that passes through the through-hole 10a is absorbed by the damper 19. This makes it possible to suppress the absorption, reflection, and diffusion of the laser light 55 by the levitation unit 10. This enables a stable process.

In this embodiment, laser light 15 and laser light 55 are successively irradiated onto the workpiece 16 being transported by the transport unit 11. Laser light 15 and laser light 55 are also simultaneously irradiated onto different locations on the workpiece 16 being transported. This shortens the time interval between the dehydrogenation annealing process and the crystallization annealing process, thereby widening the process margin.

In addition, in this embodiment, an optical scanner 305 is provided in the optical system unit 30. The optical scanner 305 is, for example, a galvanometer mirror, and scans the laser light in the X direction. By doing so, the irradiation time during which the laser light is continuously irradiated onto a specific location on the workpiece 16 can be shortened. This makes it possible to prevent heating of the base film, etc., and enables stable processing.

Furthermore, the laser irradiation device 1 has multiple optical system units 30a to 30d. This allows the area irradiated by one optical system unit 30 to be reduced. This allows the transport speed in the X direction to be improved, thereby shortening the process time (takt time). This in turn allows for improved productivity. Note that in Figure 8, optical system units 30a to 30d are each provided with independent Y drive mechanisms 32a to 32d, but the Y drive mechanism 32 for optical system units 30a to 30d may also be shared.

The method according to this embodiment includes the steps of: transporting a substrate on which a film has been formed in a first direction using a transport unit; generating blue laser light using a semiconductor laser light source; guiding the laser light to the substrate using an optical system unit movable in a second direction different from the first direction in a top view; driving the optical system unit to change the irradiation position of the laser light on the substrate in the second direction; generating excimer laser light for crystallizing the film using an excimer laser light source; and guiding the excimer laser light as a line beam whose longitudinal direction is inclined from the first direction in a top view to the substrate during transportation. This improves productivity. Furthermore, a light source other than an excimer laser light source may be used as the crystallization laser light source 51. For example, a semiconductor laser light source may be used as the crystallization laser light source 51 instead of an excimer laser light source.

Examples will be described below with reference to Fig. 10 and Fig. 11. Fig. 10 is a scanning electron microscope (SEM) photograph showing a silicon film processed by the laser irradiation apparatus according to this embodiment. As shown in Fig. 10, the silicon film is uniformly processed.

Figure 11 is a SIMS (Secondary Ion Mass Spectrometry) profile showing hydrogen concentration. In Figure 11, BLD indicates the hydrogen concentration of a silicon film annealed using the laser irradiation device of this embodiment. RTA indicates the hydrogen concentration of a silicon film annealed at 500°C using an RTA (Rapid Thermal Anneal) device. Figure 11 also shows the hydrogen concentration of a silicon film that has not been annealed.

When annealed in an RTA apparatus, the hydrogen concentration of the silicon film is approximately 0.5 atom %. On the other hand, when annealed in the laser irradiation apparatus according to this embodiment, the hydrogen concentration of the silicon film is 0.2 atom % . Therefore, the dehydrogenation process can be performed more effectively by using the laser irradiation apparatus 1 according to this embodiment.

The laser irradiation method using the above-described laser irradiation device 1 is suitable for a display manufacturing method. For example, a display manufacturing method includes the steps of forming a film on a substrate and irradiating the film with laser light using the above-described irradiation method. The configuration of embodiment 3 can be appropriately combined with the configurations of embodiments 1 and 2.

(Organic EL display)
The semiconductor device having the polysilicon film is suitable for a TFT (Thin Film Transistor) array substrate for an organic EL (ElectroLuminescence) display, in which the polysilicon film is used as a semiconductor layer having a source region, a channel region, and a drain region of the TFT.

The following describes a configuration in which the semiconductor device of this embodiment is applied to an organic EL display. Figure 12 is a cross-sectional view showing a simplified pixel circuit of an organic EL display. The organic EL display 300 shown in Figure 12 is an active matrix display device in which a TFT is arranged in each pixel PX.

The organic EL display 300 includes a substrate 310, a TFT layer 311, an organic layer 312, a color filter layer 313, and a sealing substrate 314. Figure 12 shows a top-emission organic EL display in which the sealing substrate 314 side is the viewing side. Note that the following description shows one example configuration of an organic EL display, and this embodiment is not limited to the configuration described below. For example, the semiconductor device according to this embodiment may be used in a bottom-emission organic EL display.

The substrate 310 is a glass substrate or a metal substrate. A TFT layer 311 is provided on the substrate 310. The TFT layer 311 has a TFT 311a arranged in each pixel PX. The TFT layer 311 also has wiring (not shown) connected to the TFT 311a. The TFT 311a and the wiring form a pixel circuit.

An organic layer 312 is provided on the TFT layer 311. The organic layer 312 has an organic EL element 312a arranged for each pixel PX. Furthermore, the organic layer 312 is provided with partition walls 312b between the pixels PX to separate the organic EL elements 312a.

A color filter layer 313 is provided on the organic layer 312. The color filter layer 313 is provided with color filters 313a for color display. That is, each pixel PX is provided with a resin layer colored R (red), G (green), or B (blue) as the color filter 313a.

A sealing substrate 314 is provided on top of the color filter layer 313. The sealing substrate 314 is a transparent substrate such as a glass substrate, and is provided to prevent deterioration of the organic EL light-emitting elements in the organic layer 312.

The current flowing through the organic EL element 312a of the organic layer 312 varies depending on the display signal supplied to the pixel circuit. Therefore, by supplying a display signal corresponding to the display image to each pixel PX, the amount of light emitted by each pixel PX can be controlled. This allows the desired image to be displayed.

In active matrix display devices such as organic EL displays, one pixel PX is provided with one or more TFTs (e.g., switching TFTs or driving TFTs). The TFTs in each pixel PX are provided with a semiconductor layer having a source region, a channel region, and a drain region. The polysilicon film of this embodiment is suitable for the semiconductor layer of a TFT. In other words, by using a polysilicon film manufactured by the above-described manufacturing method as the semiconductor layer of a TFT array substrate, it is possible to suppress in-plane variations in TFT characteristics. Therefore, display devices with excellent display characteristics can be manufactured with high productivity.

(Method for manufacturing semiconductor device)
The method for manufacturing a semiconductor device using the laser irradiation apparatus according to this embodiment is suitable for manufacturing a TFT array substrate. The method for manufacturing a semiconductor device having TFTs will be described with reference to FIGS. 13 and 14. FIGS. 13 and 14 are cross-sectional views showing the manufacturing process of a semiconductor device. In the following description, a method for manufacturing a semiconductor device having inverted staggered TFTs will be described. FIGS. 13 and 14 show the step of forming a polysilicon film in the semiconductor manufacturing method. Note that, as known techniques can be used for the other manufacturing steps, their description will be omitted.

As shown in Figure 13, a gate electrode 402 is formed on a glass substrate 401. A gate insulating film 403 is formed on the gate electrode 402. An amorphous silicon film 404 is formed on the gate insulating film 403. The amorphous silicon film 404 is arranged so as to overlap the gate electrode 402 with the gate insulating film 403 interposed therebetween. For example, the gate insulating film 403 and the amorphous silicon film 404 are formed successively by a CVD (Chemical Vapor Deposition) method.

Then, by irradiating the amorphous silicon film 404 with laser light L1, a polysilicon film 405 is formed, as shown in FIG. 14. That is, the amorphous silicon film 404 is dehydrogenated using the laser irradiation apparatus 1 described above. Furthermore, the amorphous silicon film 404 is crystallized using the laser irradiation apparatus 1 of embodiments 2 and 3. As a result, a polysilicon film 405 in which the silicon is crystallized is formed on the gate insulating film 403. The amorphous silicon film 404 or polysilicon film 405 corresponds to the above-mentioned film 16b.

Furthermore, in the above explanation, the laser annealing apparatus according to this embodiment was described as forming a polysilicon film by irradiating an amorphous silicon film with laser light, but it may also form a microcrystalline silicon film by irradiating an amorphous silicon film with laser light. Furthermore, the laser light used for annealing is not limited to a blue laser diode or an Nd:YAG laser.

The method according to this embodiment can also be applied to a laser irradiation device that irradiates laser light onto thin films other than silicon films. In other words, the method according to this embodiment can be applied to any laser irradiation device that irradiates laser light onto an amorphous film to form a crystallized film. The laser irradiation device 1 can also be used for laser annealing processes 2 that dehydrogenate thin films other than silicon films. The laser irradiation device according to this embodiment can appropriately modify a substrate with a crystallized film.

The laser irradiation method according to this embodiment is a laser irradiation method for performing a dehydrogenation treatment on a film provided on a substrate. The laser irradiation method includes the steps of generating blue laser light using a semiconductor laser light source, guiding the laser light to the substrate using an optical system unit, and changing the irradiation position of the laser light on the substrate.

Some or all of the embodiments 1 to 3 can be used in combination as appropriate. Note that the present invention is not limited to the above embodiments and can be modified as appropriate within the scope of the spirit of the invention.

REFERENCE SIGNS LIST 1 laser irradiation device 10 levitation unit 11 transport unit 12 holding mechanism 13 moving mechanism 15 laser light 16 object to be processed 16a substrate 16b film 19 damper 30 optical system unit 32 Y drive mechanism 301 lens 302 mirror 303 lens 40 stage

Claims (30)

A laser irradiation device that irradiates laser light onto an amorphous silicon film provided on a transparent substrate,
a semiconductor laser light source that generates laser light having a wavelength at least a part of which is transmitted through the amorphous silicon film in order to perform a dehydrogenation treatment on the amorphous silicon film;
an optical system unit that guides the laser light to the transparent substrate;
a floating unit having a through hole provided directly below the irradiation position of the laser light and floating the transparent substrate;
a transport unit that transports the transparent substrate floating on the floating unit in a first direction;
a drive stage that is disposed on the floating unit and that holds the optical system unit so as to be movable in a second direction different from the first direction when viewed from above;
an excimer laser light source that generates excimer laser light for crystallizing the amorphous silicon film;
a crystallization optical system that guides the excimer laser light as a line beam having a longitudinal direction in the second direction as viewed from above to a location on the transparent substrate that has been irradiated with the laser light while being transported;
A laser irradiation device comprising: 2. The laser irradiation device according to claim 1, wherein the wavelength of the laser light from the semiconductor laser light source is 355 nm or more and 808 nm or less. the semiconductor laser light source generates a CW laser beam;
3. The laser irradiation device according to claim 1, wherein the CW laser light is converted into pulsed laser light by a modulator and the pulsed laser light is irradiated onto the amorphous silicon film . 4. The laser irradiation device according to claim 1, wherein , when viewed from above, the longitudinal direction of the spot shape of the laser light on the transparent substrate is inclined from the first direction and the second direction. 5. The laser irradiation device according to claim 1, wherein the drive stage drives the optical system unit at a speed faster than a substrate transport speed of the transport unit. The laser irradiation device described in any one of claims 1 to 5, further comprising a damper that absorbs laser light that has passed through the through hole. 7. The laser irradiation device according to claim 1, wherein the semiconductor laser light source is a semiconductor laser light source that generates laser light having a wavelength of 500 nm or less. 8. The laser irradiation device according to claim 1, wherein the laser light from the semiconductor laser light source is incident on the optical system unit via an optical fiber. 9. The laser irradiation device according to claim 1, wherein the drive stage movably holds a plurality of the optical system units. 9. The laser irradiation device according to claim 1 , wherein the optical system unit is provided with an optical scanner that scans the laser light. A laser irradiation method for irradiating an amorphous silicon film provided on a transparent substrate with laser light, comprising:
(A1) floating the transparent substrate by a floating unit having a through hole provided directly below the irradiation position of the laser light;
(A2) generating laser light having a wavelength at least a part of which is transmitted through the amorphous silicon film by a semiconductor laser light source ;
(A3) a step of guiding the laser light to the floating transparent substrate by an optical system unit in order to perform a dehydrogenation treatment on the amorphous silicon film ,
transporting the transparent substrate floating on the floating unit in a first direction;
a step of moving the optical system unit in a second direction by a drive stage so as to change an irradiation position of the laser light in the second direction different from the first direction when viewed from above;
generating an excimer laser beam for crystallizing the amorphous silicon film by an excimer laser light source;
and guiding the excimer laser light as a line beam having a longitudinal direction in the second direction as viewed from above by a crystallization optical system to a portion of the transparent substrate being transported that has been irradiated with the laser light.
Laser irradiation method. 12. The laser irradiation method according to claim 11, wherein the wavelength of the laser light from the semiconductor laser light source is 355 nm or more and 808 nm or less. the semiconductor laser light source generates a CW laser beam;
13. The laser irradiation method according to claim 12 , wherein the CW laser light is converted into pulsed laser light by a modulator and the pulsed laser light is irradiated onto the amorphous silicon film . forming a spot shape of the laser light on the transparent substrate into a rectangular shape;
14. The laser irradiation method according to claim 11, wherein , in a top view, a longitudinal direction of a spot shape of the laser light on the transparent substrate is inclined from the first direction and the second direction. 15. The laser irradiation method according to claim 11, wherein the driving stage drives the optical system unit at a speed faster than a transport speed of the transparent substrate. The laser irradiation method according to any one of claims 11 to 15 , wherein the laser light that has passed through the through hole is absorbed by a damper. The laser irradiation method according to any one of claims 11 to 16, wherein the laser light is a laser light having a wavelength of 500 nm or less generated by the semiconductor laser light source. 18. The laser irradiation method according to claim 11, wherein the laser light from the semiconductor laser light source is incident on the optical system unit via an optical fiber. 19. The laser irradiation method according to claim 11, wherein the drive stage movably holds a plurality of the optical system units. The laser irradiation method according to any one of claims 11 to 19 , wherein the laser light is scanned by an optical scanner provided in the optical system unit. (S1) an irradiation step of irradiating a laser beam onto an amorphous silicon film formed on a transparent substrate;
The (S1) irradiation step includes:
(SA1) floating the transparent substrate by a floating unit having a through hole provided directly below the irradiation position of the laser light;
(SA2) generating laser light having a wavelength at least a part of which is transmitted through the amorphous silicon film by a semiconductor laser light source ;
(SA3) a step of guiding the laser light to the floating transparent substrate by an optical system unit in order to perform a dehydrogenation treatment on the amorphous silicon film ,
transporting the transparent substrate floating on the floating unit in a first direction;
a step of moving the optical system unit in a second direction by a drive stage so as to change an irradiation position of the laser light in the second direction different from the first direction when viewed from above;
generating an excimer laser beam for crystallizing the amorphous silicon film by an excimer laser light source;
A method for manufacturing a display , further comprising a step of using a crystallization optical system to guide the excimer laser light to the transparent substrate being transported as a line beam having a longitudinal direction in the second direction when viewed from above . 22. The method for manufacturing a display according to claim 21, wherein the wavelength of the laser light from the semiconductor laser light source is 355 nm or more and 808 nm or less. the semiconductor laser light source generates a CW laser beam;
23. The method for manufacturing a display according to claim 21, wherein the CW laser light is converted into pulsed laser light by a modulator and the pulsed laser light is irradiated onto the amorphous silicon film . forming a spot shape of the laser light on the transparent substrate into a rectangular shape;
24. A method for manufacturing a display according to any one of claims 21 to 23, wherein , when viewed from above, the longitudinal direction of the spot shape of the laser light on the transparent substrate is tilted from the first direction and the second direction. The method for manufacturing a display according to any one of claims 21 to 24, wherein the drive stage drives the optical system unit at a speed faster than a transport speed of the transparent substrate. 26. The method for manufacturing a display according to claim 21, wherein the laser light that has passed through the through-hole is absorbed by a damper. The method for manufacturing a display according to any one of claims 21 to 26, wherein the laser light is laser light having a wavelength of 500 nm or less generated by the semiconductor laser light source. The method for manufacturing a display according to any one of claims 21 to 27, wherein the laser light from the semiconductor laser light source is incident on the optical system unit via an optical fiber. The method for manufacturing a display according to any one of claims 21 to 28, wherein the drive stage movably holds a plurality of the optical system units. The method for manufacturing a display according to any one of claims 21 to 29 , wherein the laser light is scanned by an optical scanner provided in the optical system unit.