CONVEYANCE APPARATUS, CONVEYANCE METHOD, AND METHOD FOR MANUFACTURING SEMICONDUCTOR DEVICE

A conveyance apparatus configured to convey a substrate (100) in order to irradiate the substrate (100) with laser light for forming a line-shaped irradiation area (15a) according to an embodiment includes a levitation unit (10) configured to levitate the substrate (100) over its top surface, a holding mechanism (12) configured to hold the substrate (100), and a moving mechanism (13) configured to move the holding mechanism (12) in a direction inclined from a direction perpendicular to a longitudinal direction of the line-shaped laser light in a plan view so as to change an irradiation place of the laser light in the substrate (100).

TECHNICAL FIELD

The present disclosure relates to a conveyance apparatus, a conveyance method, and a method for manufacturing a semiconductor device.

BACKGROUND ART

Patent Literature 1 discloses a laser annealing apparatus for forming a polycrystalline silicon thin film. In Patent Literature 1, a projection lens focuses laser light over a substrate so that a linear irradiation area is formed therein. As a result, an amorphous silicon film is crystallized and becomes a polysilicon film.

In Patent Literature 1, a conveyance unit conveys the substrate in a state where the substrate is levitated, i.e., floated, by a levitation unit. Further, the substrate is carried into and out of the levitation unit at the same place therein. The conveyance unit conveys the substrate along each of the sides of the levitation unit. Further, the substrate moves round twice (i.e., is conveyed so as to go round along the four sides of the levitation unit twice) over the levitation unit, so that substantially the entire surface of the substrate is irradiated with laser light.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

In such a conveyance apparatus for a laser irradiation apparatus, it is desired to appropriately convey a substrate so that a laser irradiation process is performed at a high speed and in a stable manner.

Other problems to be solved and novel features will become apparent from descriptions in this specification and accompanying drawings.

According to an embodiment, a conveyance apparatus configured to convey a substrate in order to irradiate the substrate with line-shaped laser light includes: a substrate levitation unit configured to levitate the substrate over its top surface; a holding mechanism configured to hold the substrate; and a moving mechanism configured to move the holding mechanism in a direction inclined from a direction perpendicular to the line-shaped laser light in a plan view so as to change an irradiation place of the laser light in the substrate.

According to another embodiment, a conveyance apparatus configured to convey a substrate in order to irradiate the substrate with line-shaped laser light includes: a first substrate levitation unit disposed below the substrate, the first substrate levitation unit being configured to levitate the substrate, and being disposed at a part of the substrate extending from a central part of the substrate to one end thereof in a plan view; a second substrate levitation unit disposed below the substrate, the second substrate levitation unit being configured to levitate the substrate, and being disposed at another part of the substrate extending from the central part of the substrate to the other end thereof in the plan view; a holding mechanism disposed below the central part of the substrate, the holding mechanism being configured to hold the substrate by absorbing the substrate; and a moving mechanism configured to move the holding mechanism along a gap between the first and second substrate levitation units in order to move the substrate with respect to an irradiation place of the laser light.

According to another embodiment, a conveyance method for conveying a substrate in order to irradiate the substrate with line-shaped laser light includes the steps of: (a) levitating, by a levitation unit disposed below the substrate, the substrate over its top surface; (b) holding, by a holding mechanism, the substrate; and (c) moving the holding mechanism in a direction inclined from a direction perpendicular to a longitudinal direction of the line-shaped laser light in a plan view so as to change an irradiation place of the laser light in the substrate.

According to another embodiment, a conveyance method for conveying a substrate in order to irradiate the substrate with line-shaped laser light includes the steps of: (A) levitating a part of the substrate extending from a central part of the substrate to one end thereof in a plan view by using a first substrate levitation unit disposed below the substrate, and levitating another part of the substrate extending from the central part of the substrate to the other end thereof in the plan view by using a second substrate levitation unit disposed below the substrate; (B) holding the substrate by absorbing the substrate by using a holding mechanism disposed below the central part of the substrate; and (C) moving the holding mechanism along a gap between the first and second substrate levitation units in order to move the substrate with respect to an irradiation place of the laser light.

According to another embodiment, a method for manufacturing a semiconductor device includes the steps of: (s1) forming an amorphous film over a substrate; and (s2) annealing the amorphous film by irradiating the substrate with line-shaped laser light so as to crystallize the amorphous film and thereby form a crystallized film, in which the annealing step (s2) includes the steps of: (sa) levitating, by a levitation unit, the substrate over its top surface; (sb) holding, by a holding mechanism, the substrate; and (sc) moving the holding mechanism in a direction inclined from a direction perpendicular to a longitudinal direction of the line-shaped laser light in a plan view so as to change an irradiation place of the laser light in the substrate.

According to another embodiment, a method for manufacturing a semiconductor device includes the steps of: (S1) forming an amorphous film over a substrate; and (S2) annealing the amorphous film by irradiating the substrate with line-shaped laser light so as to crystallize the amorphous film and thereby form a crystallized film, in which the annealing step (S2) includes the steps of: (SA) levitating a part of the substrate extending from a central part of the substrate to one end thereof in a plan view by using a first substrate levitation unit disposed below the substrate, and levitating another part of the substrate extending from the central part of the substrate to the other end thereof in the plan view by using a second substrate levitation unit disposed below the substrate; (SB) holding the substrate by absorbing the substrate by using a holding mechanism disposed below the central part of the substrate; and (SC) moving the holding mechanism along a gap between the first and second substrate levitation units in order to move the substrate with respect to an irradiation place of the laser light.

According to the above-described embodiments, it is possible to perform conveyance of a substrate suitable for a laser irradiation process.

DESCRIPTION OF EMBODIMENTS

A conveyance apparatus according to an embodiment is used in a laser irradiation apparatus such as a laser annealing apparatus. The laser annealing apparatus is, for example, an ELA (Excimer Laser Anneal) apparatus that forms an LTPS (Low Temperature Poly-Silicon) film. A conveyance apparatus, a laser irradiation apparatus, a method, and a manufacturing method according to this embodiment will be described hereinafter with reference to the drawings.

First Embodiment

A configuration of a conveyance apparatus and that of a laser irradiation apparatus will be described with reference toFIGS.1and2.FIG.1is a plan view schematically showing the configuration of the laser irradiation apparatus1.FIG.2is a side cross-sectional view schematically showing the configuration of the laser irradiation apparatus1.

Note that in the drawings described below, an xyz three-dimensional orthogonal coordinate system is shown as appropriate for the sake of simplification of the description. The z direction is a vertical direction and the y direction is a direction along a linear irradiation area15a. The x direction is a direction perpendicular to the z and Y directions. That is, the y direction is the longitudinal direction, i.e., the long-side direction, of the linear irradiation area15a, and the x direction is the lateral direction, i.e., the short-side direction, perpendicular to the longitudinal direction.

As shown inFIGS.1and2, the laser irradiation apparatus1includes a levitation unit10, a conveyance unit11, and a laser irradiation unit14. The levitation unit10and the conveyance unit11constitute a conveyance apparatus.

As shown inFIG.2, the levitation unit10is configured to eject a gas from its surface. The levitation unit10levitates, i.e., floats, an object to be processed16over its top surface. The object to be processed16is levitated as the gas ejected from the surface of the levitation unit10is blown onto the bottom surface of the object to be processed16. For example, the object to be processed16is a glass substrate. When the object to be processed16is conveyed, the levitation unit10adjusts the levitation height of the object to be processed16so that it does not come into contact with other mechanisms (not shown) disposed above the object to be processed16.

The conveyance unit11conveys the levitated object to be processed16in the conveyance direction. As shown inFIG.1, the conveyance unit11includes a holding mechanism12and a moving mechanism13. The holding mechanism12holds the object to be processed16. For example, the holding mechanism12can be formed by using a vacuum absorption mechanism. The vacuum absorption mechanism is formed by a metal material such as an aluminum alloy. Alternatively, the holding mechanism12can be formed of a resin-based material such as a PEEK (polyether ether ketone) material. Absorption grooves, absorption holes, or the like are formed on the top surface of the holding mechanism12. The holding mechanism12may be formed of a porous material.

The holding mechanism12(the vacuum absorption mechanism) is connected to an exhaust port (not shown) and the exhaust port is connected to an ejector, a vacuum pump, or the like. Therefore, since a negative pressure for sucking a gas acts on the holding mechanism12, the object to be processed16can be held by using the holding mechanism12.

Further, the holding mechanism12includes a raising/descending mechanism (not shown) for performing an absorption operation. The raising/descending mechanism includes, for example, an air cylinder or an actuator such as a motor. For example, the holding mechanism12absorbs the object to be processed16in a state where the holding mechanism12is raised to an absorption position. Further, the holding mechanism12descends to a standby position in a state where the absorption is cancelled, i.e., ceased.

The holding mechanism12holds the object to be processed16by sucking the surface (the bottom surface) of the object to be processed16opposite to the surface (the top surface) thereof to which laser light15is applied, i.e., by sucking the surface of the object to be processed16that is opposed to the levitation unit10. Further, the holding mechanism12holds the end of the object to be processed16in the +y direction (i.e., the end of the object to be processed16on the positive side in the y direction).

The moving mechanism13included in the conveyance unit11is connected to the holding mechanism12. The moving mechanism13is configured to be able to move the holding mechanism12in the conveyance direction. The conveyance unit11(the holding mechanism12and the moving mechanism13) is disposed at an end of the levitation unit10in the +y direction. Further, the object to be processed16is conveyed as the moving mechanism13moves in the conveyance direction while the holding mechanism12is holding the object to be processed16.

As shown inFIG.1, for example, the moving mechanism13is configured to slide in the conveyance direction at the end of the levitation unit10in the +y direction. As the moving mechanism13slides in the conveyance direction at the end of the levitation unit10, the object to be processed16is conveyed along the conveyance direction. The conveyance direction is inclined from the x direction. For example, when the angle between the x direction and the conveyance direction is represented by θ, the angle θ is larger than 0°. The angle θ is preferably equal to or smaller than 5°.

Therefore, the levitation unit10has a trapezoidal shape having four sides in the plan view. Specifically, the levitation unit10has two sides parallel to the y direction of the levitation unit10, one side parallel to the x direction, and one side inclined from the x direction (hereinafter also referred to as an inclined side10e).

Note that the conveyance speed of the object to be processed16can be controlled by controlling the moving speed of the moving mechanism13. The moving mechanism13includes, for example, an actuator such as a motor, a liner guide mechanism, an air bearing, etc. (not shown).

The object to be processed16is irradiated with laser light15. Note that the irradiation area15aof the laser light15in the object to be processed16has a line-like shape whose longitudinal direction is parallel to the y direction. That is, the longitudinal direction of the irradiation area15ais parallel to the y direction, and the crosswise direction thereof is parallel to the x direction.

For example, the laser irradiation unit14includes an excimer laser light source or the like that generates laser light. Further, the laser irradiation unit14includes an optical system that guides the laser light to the object to be processed16. For example, the laser irradiation unit14includes a cylindrical lens for forming the linear irradiation area15a. The object to be processed16is irradiated with line-shaped laser light, specifically, the laser light15(a line beam) whose focal point extends, i.e., stretches, in the y direction.

The object to be processed16is, for example, a glass substrate in which an amorphous film (an amorphous silicon film16b) is formed. The amorphous film can be crystallized by irradiating the amorphous film with laser light15and thereby performing an annealing process. For example, an amorphous silicon film16bcan be converted into a polycrystalline silicon film (a polysilicon film16a).

The laser irradiation apparatus1conveys the object to be processed16in the conveyance direction by holding the bottom surface of the object to be processed16using the conveyance unit11while levitating the object to be processed16using the levitation unit10. Note that when the object to be processed16is conveyed, the conveyance unit11included in the laser irradiation apparatus1conveys the object to be processed16while the conveyance unit11is holding a part of the object to be processed16that does not overlap the irradiation area15ain a plan view, i.e., as viewed in the z-direction. That is, as shown inFIG.1, when the object to be processed16is conveyed in the conveyance direction, the part of the object to be processed16at which the conveyance unit11holds the object to be processed16(which corresponds to the position of the holding mechanism12) does not overlap the irradiation area15a.

For example, a planar shape of the object to be processed16is a quadrangle (a rectangular) having four sides and the conveyance unit11(the holding mechanism12) holds only one of the four sides of the object to be processed16. Further, the conveyance unit11(the holding mechanism12) holds a part of the object to be processed16that is not irradiated with laser light in a period during which the object to be processed16is being conveyed.

By the above-described configuration, it is possible to position the part of the object to be processed16at which the conveyance unit11holds the object to be processed16(which corresponds to the position of the holding mechanism12) and the irradiation area15aaway from each other. The irradiation area15acorresponds to roughly a half of the object to be processed16in the −y direction, and the conveyance unit11holds the end the object to be processed16in the +y direction. It is possible to increase the distance between the place near the holding mechanism12where the object to be processed16is bent widely and the irradiation area15a. Therefore, it is possible to reduce the effect of the bending of the object to be processed16caused by the holding mechanism12when laser light is applied to the object to be processed16.

In the y direction, the length of the irradiation area15ais about half the length of the object to be processed16. Therefore, when the object to be processed16passes the laser irradiation place15aonce, the amorphous silicon film in substantially a half of the area of the object to be processed16is crystallized. Then, after the object to be processed16is rotated about the z-axis by 180 degrees by a rotation mechanism (not shown), the conveyance unit11conveys the object to be processed16in the −x direction. Alternatively, after the rotated object to be processed16is conveyed in the −x direction, the conveyance unit11may convey the object to be processed16again in the +x direction. Then, when the object to be processed16is conveyed in the −x direction or when the object to be processed16is conveyed in the +x direction again after the rotation of 180 degrees, laser light is applied to the object to be processed16. In this way, the object to be processed16passes through the laser irradiation place15a, and the amorphous silicon film in the remaining half of the object to be processed16is crystallized. By making the object to be processed16perform a reciprocating movement as described above, the amorphous silicon film is converted into a polycrystalline silicon film over the substantially entire area of the object to be processed16.

Further, the conveyance direction is inclined from the x direction, which is perpendicular to the linear irradiation area15a. That is, the object to be processed16is conveyed in the conveyance direction inclined from the edge of the rectangular object to be processed16. By inclining the conveyance direction from the x direction in the plan view, it is possible to perform conveyance of a substrate suitable for a laser irradiation process. Therefore, it is possible to appropriately perform a process for crystallizing a silicon film, and thereby to improve the display quality. By the above-described configuration, for example, it is possible to prevent an occurrence of a moire.

Assume that, for example, the object to be processed16is a glass substrate for an organic EL (Electro-Luminescence) display device. When the display area of the organic EL display device is rectangular, the edges of the display area are parallel to the edges of the object to be processed16. That is, the organic EL display device has a rectangular display area whose short sides are parallel to the x and y directions. When the conveyance direction is parallel to the x direction, laser light is applied to the object to be processed16in a state where the direction in which pixels are arranged is parallel to the irradiation area15a.

As shown in this embodiment, it is possible to appropriately perform a laser irradiation process by inclining the conveyance direction from the x direction. The moving mechanism13moves the holding mechanism12in the conveyance direction inclined from the x direction perpendicular to the longitudinal direction of the linear irradiation area15ain the plan view so as to change the irradiation place of the laser light in the object to be processed16. In this way, it is possible to appropriately perform a process for crystallizing a silicon film. For example, it is possible to prevent an occurrence of a moire and thereby to improve the display quality.

This feature will be described in detail.FIG.3is a diagram for explaining a distribution of energy intensity when pulsed laser light is applied. Here, it is assumed that the laser light15is pulsed laser light having a constant repetition frequency. Further, the pulsed laser light is applied to the object to be processed16while the object to be processed16is being conveyed.

The laser light15has a distribution of intensity as shown inFIG.3. For example, inFIG.3, the distribution of intensity of the laser light15is a Gaussian distribution. Further, the object to be processed16is conveyed so that consecutive pulsed laser lights partially overlap with one another. That is, the conveyance distance corresponding to the repetition frequency of the pulsed laser light is shorter than the spot width in the crosswise direction of the laser light. In the object to be processed16, a spot of given one pulse of the laser light15partially overlaps with that of the next one pulse thereof.

Here, it is assumed that the object to be processed16is a TFT array substrate. The relation between the manufacturing pitch of TFTs and the irradiation pitch of laser will be described with reference toFIGS.4and5. Each ofFIGS.4and5is a plan view schematically showing a laser irradiation pitch in an object to be processed16. Further, each ofFIGS.4and5shows an enlarged view of the object to be processed16.FIG.4shows a comparative example in which the direction perpendicular to the line-shaped laser light is parallel to the conveyance direction.FIG.5shows an example of this embodiment in which the direction perpendicular to the line-shaped laser light is inclined from the conveyance direction.

In the comparative example shown inFIG.4, the edges of the object to be processed16are parallel to the line-shaped laser light. The edges of the object to be processed16are parallel to the x or y direction. Each of irradiation lines15fof the laser light is a straight line indicating the center of the irradiation area15aof the laser light, and is parallel to the longitudinal direction of the irradiation area. InFIG.4, the irradiation lines15fare parallel to the y direction, and the irradiation lines15fare perpendicular to the conveyance direction of the object to be processed16. Since the conveyance speed of the object to be processed16is constant, the irradiation lines15fare arranged at equal intervals. The interval of the irradiation lines15fis defined as the irradiation pitch. The irradiation pitch is determined by the repetition frequency of the pulsed laser light and the conveyance speed.

Each of gate electrodes402and source electrodes407is formed parallel to the edges of the object to be processed16. InFIG.4, the gate electrodes402are parallel to the y direction and also parallel to the source electrodes407. TFTs313aare arranged along the x and y directions. The manufacturing pitch of TFTs corresponds to the interval between the gate electrodes402.

In the x direction, the laser irradiation pitch is different from the manufacturing pitch of the TFTs. When the two different pitches overlap with each other, a striped pattern, i.e., a moire, visually appears due to the undulation (beat) of figures. Note that, strictly speaking, due to a small deviation in the starting position of the laser irradiation, the position of the irradiation line of the second laser irradiation (the lower half surface inFIG.4) is deviated from that of the first laser irradiation line (the upper half surface inFIG.4).

In the example of this embodiment shown inFIG.5, the irradiation lines15fare inclined from the conveyance direction of the object to be processed16. Since the object to be processed16is conveyed in the direction perpendicular to the longitudinal direction of the laser light, the periodicity of the shape that appears in the same direction in the comparative example is eliminated. As a result, a moire become less likely to be visible. As described above, by conveying the object to be processed16in a direction inclined from the direction perpendicular to the longitudinal direction of the line-shaped laser light, the occurrence of a moire can be prevented.

Note that, depending on the angle of the irradiation lines15f, there are cases where the moire is not eliminated or a different type of moire occurs. In such a case, the angle of the irradiation lines15fmay be adjusted according to the manufacturing pitch of the TFTs and the like. Note that, strictly speaking, due to a small deviation in the starting position of the laser irradiation, the position of the irradiation line of the second laser irradiation (the lower half surface inFIG.4) is deviated from that of the first laser irradiation line (the upper half surface inFIG.4).

In the conveyance method according to this embodiment, the object to be processed16is conveyed in order to irradiate the object to be processed16with line-shaped laser light15. The levitation unit10levitates, i.e., floats, the object to be processed16over its top surface. The holding mechanism12holds the object to be processed16. The holding mechanism12is moves in a direction inclined from the direction perpendicular to the longitudinal direction of the line-shaped laser light in the plan view so as to change the irradiation place of the laser light15in the object to be processed16.

Second Embodiment

A conveyance apparatus according to a second embodiment will be described hereinafter with reference toFIG.6.FIG.6is a plan view schematically showing a conveyance apparatus600. Note that descriptions of the components, structures, and the like of the second embodiment that are same as those of the first embodiment are omitted as appropriate.

The conveyance apparatus600includes a levitation unit10and end levitation units671to676. The levitation unit10levitates a substrate (not shown inFIG.6), which is the object to be processed. Similarly to the first embodiment, the levitation unit10has a trapezoidal shape in the plan view. The levitation unit10has two sides parallel to the y direction of the levitation unit10, one side parallel to the x direction, and one side inclined from the x direction (hereinafter also referred to as an inclined side10e). The angle between the inclined side10eand the x direction is preferably larger than 0° and not larger than 5°.

Hereinafter, for the sake of explanation, the levitation unit10is divided into six areas60ato60fin the plan view. Specifically, the levitation unit10includes a first area60ato a fourth area60d, a process area60e, and a passage area60f. The first area60ais a trapezoidal area that includes the corner on the −x side and the +y side (the upper-left corner inFIG.6). The second area60bis a trapezoidal area that includes the corner on the +x side and the +y side (the upper-right corner inFIG.6). The third area60cis a trapezoidal area that includes the corner on the +x side and the −y side (the lower-right corner inFIG.6). The fourth area60dis a trapezoidal area that includes the corner on the −x side and the −y side (the lower-left corner inFIG.6).

The process area60eis a trapezoidal area located between the first and second areas60aand60b. The process area60eis an area including the irradiation area15ato which laser light is applied. The passage area60fis a rectangular area located between the third and fourth areas60cand60d.

The half of the area of the levitation unit10on the +y side (the upper half area inFIG.6) is composed of, in the order from the −x side (from the left side inFIG.6), the first area60a, the process area60e, and the second area60b. The half of the area of the levitation unit10on the −y side (the lower half area inFIG.6) is composed of, in the order from the +x side, the third area60c, the passage area60f, and the fourth area60d.

The levitation unit10includes a rotation mechanism68, and alignment mechanisms69aand69b. The rotation mechanism68rotates the substrate. Each of the alignment mechanisms69aand69baligns the substrate. The alignment mechanisms69aand69bare provided in the first and second areas60aand60b, respectively. The rotation mechanism68is provided in the fourth area60d. The operations of the rotation mechanism68, the alignment mechanisms69aand69b, and the like will be described later.

The end levitation units671to676are disposed outside the levitation unit10. The end levitation units671to676are arranged along the periphery of the trapezoidal levitation unit10. The end levitation units671to676are arranged along the edges of the levitation unit10. In the plan view, the end levitation units671to676are arranged so as to surround the periphery of the levitation unit10.

The end levitation units671and672are disposed on the −x side of the levitation unit10. The end levitation unit673is disposed on the +y side of the levitation unit10. The end levitation unit674is disposed on the +x side of the levitation unit10. The end levitation units675and676are disposed on the −y side of the levitation unit10. Note that at least one of the end levitation units671,672,673,674,675and676can be omitted. For example, the holding mechanism12holds an end of the substrate100. The levitation unit10levitates the remaining part of the substrate, i.e., part of the substrate other than the end thereof. By doing so, it is possible to levitate the substrate without a levitation unit(s)10disposed near the levitation unit10.

The end levitation units671and672are disposed along the edge of the levitation unit10on the −x side. That is, each of the end levitation units671and672is disposed along the y direction. Further, the width of the end levitation unit671in the x direction is wider than that of the end levitation unit672. The end levitation unit671is disposed on the −y side of the end levitation unit672.

The end levitation unit673is disposed along the edge of the levitation unit10on the +y side. That is, the end levitation unit673is disposed along the inclined side10eof the levitation unit10. The end levitation unit674is disposed along the edge of the levitation unit10on the +x side. That is, each of the end levitation units674is provided along the y direction.

The end levitation units675and676are disposed along the edge of the levitation unit10on the −y side. That is, each of the end levitation units675and676is provided along the x direction. Further, the width of the end levitation unit676in the y direction is wider than that of the end levitation unit675. The end levitation unit676is disposed on the −x side of the end levitation unit675.

A conveyance unit11ais provided between the levitation unit10and the end levitation unit671. A part of the conveyance unit11ais disposed between the levitation unit10and the end levitation unit672. The conveyance unit11ais formed along the y direction. The conveyance unit11aconveys the substrate in the +y direction. That is, the conveyance unit11aconveys the substrate100from the fourth area60dtoward the first area60a.

A conveyance unit11bis provided between the levitation unit10and the end levitation unit673. The conveyance unit11bis formed along the inclined side10e. The conveyance unit11bconveys the substrate in a direction parallel to the inclined side10e. That is, the conveyance unit11bconveys the substrate100from the first area60atoward the second area60b.

A conveyance unit11cis provided between the levitation unit10and the end levitation unit674. The conveyance unit11cis formed along the y direction. The conveyance unit11cconveys the substrate100in the −y direction. That is, the conveyance unit11cconveys the substrate100from the second area60btoward the third area60c.

A conveyance unit11dis provided between the levitation unit10and the end levitation unit675. A part of the conveyance unit11dis disposed between the levitation unit10and the end levitation unit676. The conveyance unit11dis formed along the x direction. The conveyance unit11aconveys the substrate in the −x direction. That is, the conveyance unit11dconveys the substrate from the third area60ctoward the fourth area60d.

Note that each of the conveyance units11ato11dincludes a holding mechanism12and a moving mechanism13as in the case of the first embodiment. The operations of the holding mechanism12and the moving mechanism13will be described later.

Similarly to the first embodiment, the longitudinal direction of the irradiation area15aof the laser light is parallel to the y direction. That is, a linear irradiation area15awhose longitudinal direction is parallel to the y direction is formed. The laser light is applied to the substrate while the substrate is being conveyed in the direction parallel to the inclined side10e. A laser irradiation process is performed while the substrate is moving from the first area60ato the second area60b. In this embodiment, similarly to the first embodiment, an amorphous silicon film is converted into a polysilicon film by applying laser light emitted from a laser generation apparatus to the substrate.

Note that, in the levitation unit10, a precision levitation unit111is disposed in the irradiation area15aand on the periphery thereof. The accuracy of the levitation height by the precision levitation unit111is higher than those of semi-precision levitation units and rough levitation units. Therefore, in the process area60e, which includes the irradiation area15a, the laser light is applied to the object to be processed which is being levitated with higher accuracy of the levitation height than the accuracy in the other areas60a,60b,60c,60dand60f. In this way, it is possible to apply the laser light to the object to be processed in a stable manner. Further, the areas other than the irradiation area15a, such as the passage area60f, the third area60c, and the fourth area60d, are manufactured without using an expensive precision levitation unit111. Therefore, the cost of the apparatus can be reduced.

Next, a procedure in a conveyance method using the levitation unit10will be described with reference toFIGS.7to13. In this example, the fourth area60dis used as a place where the substrate100is carried in and carried out. Further, the substrate100carried into the fourth area60dis conveyed from one area to another in the order of the first area60a, the process area60e, the second area60b, the third area60c, the passage area60f, and the fourth area60d. That is, the substrate100moves round (circulates) along the edges of the levitation unit10, i.e., is conveyed so as to go round along the four edges of the levitation unit. Note that the substrate100moves round twice so that the entire area of the substrate100is irradiated with the laser light. That is, the substrate100is conveyed so that it moves round twice over the levitation unit10. By doing so, substantially the entire surface of the substrate100is irradiated with the laser light.

The above-described process will be described hereinafter in detail along the procedure in the conveyance method. As shown inFIG.7, the substrate100is carried into the fourth area60d. The substrate100carried into the fourth area60dis being levitated by the levitation unit10, and the end levitation units671,672and676. That is, the end of the substrate100on the −x side is being levitated by the end levitation units671and672, and the central part thereof is being levitated by the levitation unit10. The end of the substrate100on the −y side is being levitated by the end levitation unit676. Further, the holding mechanism12aof the conveyance unit11aholds the substrate100.

Next, as shown inFIG.8, the substrate100a, which is located in the fourth area60d, is conveyed to the first area60a. InFIG.8, the substrate that has been moved to the first area60ais shown as a substrate100b. The holding mechanism12aof the conveyance unit11ais holding the substrate100a. Then, a moving mechanism13amoves the holding mechanism12ain the +y direction, so that the substrate100ais moved from the fourth area60dto the first area60a(indicted by an outlined arrow inFIG.8).

Note that, in the xy-plane view, the holding mechanism12amoves in the +y direction through the gap between the levitation unit and the end levitation unit671. Further, in the xy-plane view, the holding mechanism12amoves in the +y direction though the gap between the levitation unit10and the end levitation unit672. Therefore, the substrate100bis being levitated by the levitation unit10, and the end levitation units672and673. That is, the end of the substrate100bon the −x side is being levitated by the end levitation unit672, and the central part thereof is being levitated by the levitation unit10. The end of the substrate100bon the +y side is being levitated by the end levitation unit673.

Next, as shown inFIG.9, the alignment mechanism69aaligns the position and the angle of the substrate100b, which has been conveyed to the first area60a. For example, the position and the rotation angle of the substrate100may be slightly deviated due to the carrying-in operation, the conveying operation, and/or the rotating operation of the substrate100. The alignment mechanism69acompensates for the deviation in the position and/or the rotation angle of the substrate. In this way, it is possible to accurately control the irradiation place of the laser light in the substrate100.

For example, the alignment mechanism69acan be moved in the y direction and can be rotated around the z-axis. Further, the alignment mechanism69acan be moved in the z direction. For example, the alignment mechanism69aincludes an actuator(s) such as a motor(s). The amounts of deviations in the position and the angle of the substrate100bare obtained from an image thereof taken by a camera or the like. The alignment mechanism69aperforms alignment based on these deviation amounts.

The alignment mechanism69ais disposed directly below the central part of the substrate100b. The alignment mechanism69aholds the substrate100b. The alignment mechanism69amay adsorb and hold the substrate100bin a manner similar to that of the holding mechanism12. The holding mechanism12areleases, i.e., ceases, the holding of the substrate100b. In this way, the substrate100bis handed over from the holding mechanism12ato the alignment mechanism69a.

Then, the alignment mechanism69arotates the substrate100baround the z-axis (indicted by an outlined arrow inFIG.9). The alignment mechanism69arotates the substrate100bso that the edge of the substrate100bbecomes parallel to the inclined side10eof the levitation unit10. The substrate after the rotation is shown as a substrate100c. For example, the alignment mechanism69arotates the substrate100around the z-axis by about 5°. The edge of the substrate100cis parallel to the inclined side10eof the levitation unit10. Then, after the alignment is finished, the holding mechanism12bof the conveyance unit11bholds the substrate100b, and the alignment mechanism69areleases the holding thereof. As a result, the substrate100cis handed over from the alignment mechanism69ato the holding mechanism12bof the conveyance unit11b.

Next, as shown inFIG.10, the conveyance unit11bmoves the substrate100d. As a result, the substrate100dpasses through the process area60e. In this process, in the xy-plane view, the holding mechanism12bmoves in the direction parallel to the inclined side10ethrough the gap between the levitation unit10and the end levitation unit673. In this way, substantially a half of the area of the substrate100dpasses through the irradiation area15a. The laser light is applied to the substrate100d, which is moving in the inclined direction inclined from the x direction perpendicular to the irradiation area15a.

In the xy-plane view, the holding mechanism12bmoves in the direction parallel to the inclined side10ethrough the gap between the levitation unit10and the end levitation unit673. Therefore, the substrate100dis being levitated by the levitation unit10and the end levitation unit673. That is, the end of the substrate100don the +y side is being levitated by the end levitation unit673, and the central part thereof is being levitated by the levitation unit10. A laser irradiation process is performed while the substrate is moving from the first area60ato the second area60b.

Next, as shown inFIG.11, when the substrate100ehas moved to the second area60b, the alignment mechanism69baligns the substrate100e. In this process, the alignment mechanism69brotates the substrate100e(indicted by an outlined arrow inFIG.11). InFIG.11, the substrate after the rotation is shown as a substrate100f.

The alignment mechanism69bis disposed directly below the central part of the substrate100e. The alignment mechanism69bholds the substrate100e. The alignment mechanism69bmay adsorb and hold the substrate100ein a manner similar to that of the holding mechanism12. Further, the holding mechanism12breleases the holding of the substrate100e. The substrate100eis handed over from the holding mechanism12bof the conveyance unit11bto the alignment mechanism69b.

The alignment mechanism69brotates the substrate100earound the z-axis (indicted by an outlined arrow inFIG.11). The alignment mechanism69arotates the substrate100eso that the edge of the substrate100ebecomes parallel to the inclined side10eof the levitation unit10. After the rotation, the edges of the substrate100fare parallel to the x or y direction. Then, after the alignment is finished, the holding mechanism12cof the conveyance unit11cholds the substrate100f, and the alignment mechanism69breleases the holding thereof. As a result, the substrate100fis handed over from the alignment mechanism69bto the holding mechanism12cof the conveyance unit11c.

The substrate100eis being levitated by the levitation unit10, and the end levitation units673and674. That is, the end of the substrate100eon the +y side is being levitated by the end levitation unit673. The end of the substrate100eon the +x side is being levitated by the end levitation unit674, and the central part thereof is being levitated by the levitation unit10.

Next, as shown inFIG.12, the substrate100f, which is located in the second area60b, is conveyed to the third area60c. The substrate that has moved to the third area60cis shown as a substrate100g. InFIG.12, the holding mechanism12cof the conveyance unit11cis holding the substrate100f. Then, the moving mechanism13cmoves the holding mechanism12cin the −y direction, so that the substrate100fis moved from the second area60bto the third area60c(indicted by an outlined arrow inFIG.12).

In this process, in the xy-plane view, the holding mechanism12cmoves in the −y direction through the gap between the levitation unit and the end levitation unit674. Therefore, the substrate100eis being levitated by the levitation unit10, and the end levitation units674and675. The end of the substrate100eon the +x side is being levitated by the end levitation unit674, and the central part thereof is being levitated by the levitation unit10. The end of the substrate100eon the −y side is being levitated by the end levitation unit675.

Then, the holding mechanism12dof the conveyance unit11dholds the substrate100g, and the holding mechanism12creleases the holding thereof. As a result, the substrate100gis handed over from the holding mechanism12cof the conveyance unit11cto the holding mechanism12dof the conveyance unit11d.

Next, as shown inFIG.13, the substrate100g, which is located in the third area60c, is conveyed to the fourth area60d. The substrate that has moved to the fourth area60dis shown as a substrate100h. InFIG.13, the holding mechanism12dof the conveyance unit11dis holding the substrate100g. Then, the moving mechanism13dmoves the holding mechanism12din the −x direction, so that the substrate100fis moved from the third area60cto the fourth area60d(indicted by an outlined arrow inFIG.13).

Note that, in the xy-plane view, the holding mechanism12dmoves in the −x direction through gap between the levitation unit10and the end levitation unit675. In the xy-plane view, the holding mechanism12dmoves in the −x direction through the gap between the levitation unit10and the end levitation unit676. Therefore, the substrate100his being levitated by the levitation unit10and the end levitation unit676. The end of the substrate100hon the −y side is being levitated by the end levitation unit676, and the central part thereof is being levitated by the levitation unit10. The end of the substrate100hon the −x side is being levitated by the end levitation unit671.

In this way, the substrate100, which was originally disposed in the fourth area60d, is moved from one area to another in the order of the first area60a, the process area60e, the second area60b, the third area60c, the passage area60f, and the fourth area60d. That is, the substrate100moves round along the edges of the levitation unit10.

Next, as shown inFIG.14, the rotation mechanism68rotates the substrate100haround the z-axis by 180°. That is, the substrate100his handed over from the holding mechanism12dto the rotation mechanism68. After the rotation mechanism68rotates the substrate100h, the substrate100his handed over from the rotation mechanism68to the holding mechanism12d.

Similarly to the above-described processes, the conveyance units11ato11dmove the substrate100hagain from one area to another in the order of the first area60a, the process area60e, the second area60b, the third area60c, the passage area60f, and the fourth area60d. That is, as shown inFIGS.7to13, the substrate100moves round along the edges of the levitation unit10.

In this example, the rotation mechanism68rotates the substrate100hby 180°. When the substrate100epasses through the process area60efor the second time, the laser light is applied to the remaining half of the area of the substrate that was not irradiated with the laser light in the first passage. As described above, the substrate100moves round twice along the edges of the levitation unit10. Since the substrate100is rotated 180° between the first laser irradiation and the second laser irradiation, substantially the entire surface of the substrate100is irradiated with the laser light. Note that the place in which the substrate100is rotated is not limited to the first area60a. For example, the rotation may be performed in the second area60b, the third area60c, the fourth area60d, or the like.

In this embodiment, the moving mechanism13balso conveys the holding mechanism12bin a direction inclined from the x direction perpendicular to the irradiation area15a. Therefore, it is possible to appropriately perform a process for crystallizing a silicon film. For example, it is possible to prevent an occurrence of a moire and thereby to improve the display quality.

Next, an example of the holding mechanism12will be described with reference toFIG.15.FIG.15is a perspective view schematically showing a part of a holding mechanism12.FIG.15shows the holding mechanism12which moves in the y direction as in the case of the holding mechanism12cshown inFIG.13.FIG.15shows a structure of an end of the holding mechanism12on the −y side.

The holding mechanism12includes a plurality of absorption cells121. The plurality of absorption cells121are arranged along the conveyance direction. A recess122is formed between two absorption cells121. The holding mechanism12is formed of, for example, a metal material such as aluminum. For example, the plurality of absorption cells121can be integrally formed by an aluminum alloy such as A5052.

The top surfaces of the absorption cells121form an absorption surface121afor adsorbing a substrate100(not shown inFIG.15).FIG.16shows an enlarged view of the absorption surface121aand a cross-sectional view of the absorption cell121. Absorption grooves126are formed in the absorption surface121a. Further, the absorption grooves126are connected to air-intake holes125. The air-intake holes125are connected to an internal space127formed inside the absorption cell121. As the air in the internal space127is exhausted by a pump or the like, the intake holes125and the absorption grooves126have a negative pressure. In this way, a substrate100is vacuum-adsorbed onto the absorption surface121aof each absorption cell121.

As shown inFIG.17, a valve129is preferably provided for each of the plurality of absorption cells121. For example, the absorption cells121are connected to respective exhaust ports128. The exhaust ports128are connected to piping130through the valves129. The piping130is common to the plurality of exhaust ports128. Further, the piping130is connected to exhaust means131such as a vacuum pump or an ejector. Therefore, the exhaust means131can reduce the pressure in the internal space127of each absorption cell121.

The valves129are provided for the respective absorption cells121. The plurality of valves129can be opened and closed independently of each other. The substrate100is disposed over the absorption surface121a. By opening all the valves129, each of the absorption cells121vacuum-adsorbs the bottom surface of the substrate100.

Note that there are cases where, due to an error in the conveyance of the substrate100, the absorption surfaces121aof some absorption cells121are not closed, i.e., covered, by the substrate100. As shown inFIG.18, there are cases where the absorption surfaces121aof some absorption cells121are not completely covered by the substrate100. In such cases, the valves129of the absorption cells121whose absorption surfaces121aare not closed, i.e., covered, are closed. For example, inFIG.18, the substrate100is deviated from the absorption surface121aof one of two absorption cells121located on the right side. Therefore, the valve129of the absorption cell121located on the right side is closed. InFIG.18, the substrate100is held by only the absorption cell121located on the left side. For example, the valve129is closed when the sucking flow rate of the gas in the exhaust port128increases to a threshold value or higher. In this way, it is possible to appropriately vacuum-adsorb the substrate100. Therefore, it is possible to perform conveyance of a substrate suitable for a laser irradiation process.

FIG.19is a side view schematically showing an example of the overall configuration of the conveyance apparatus600. The conveyance apparatus600includes an area base610, a pedestal620, and a conveyance stage630. Further, the conveyance apparatus600also includes a levitation unit10, a holding mechanism12, a moving mechanism13, and an end levitation unit670as described above. As shown inFIG.17and the like, piping130is connected to the holding mechanism12by a coupling or the like.

The area base610is provided over the pedestal620. The levitation unit10and the end levitation unit670are provided over the area base610. The end levitation unit670is one of the end levitation units671to676shown inFIGS.6to14.

The levitation unit10includes a semi-precision levitation unit112and a rough levitation unit113. The accuracy of levitation by the semi-precision levitation unit112is lower than that of the precision levitation unit111. The accuracy of levitation by the rough levitation unit113is lower than those of the semi-precision levitation unit112and the precision levitation unit111.

The holding mechanism12is disposed between the levitation unit10and the end levitation unit670. The moving mechanism13is disposed over the conveyance stage630. The moving mechanism13includes a guide mechanism or the like provided along the moving direction. The moving mechanism13moves the holding mechanism12as described above. Therefore, the holding mechanism12moves along the edge of the levitation unit10through the space (gap) between the levitation unit10and the end levitation unit670. By the above-described configuration, it is possible to apply laser light to the moving substrate100.

Third Embodiment

A conveyance apparatus600A according to a third embodiment will be described with reference toFIG.20.FIG.20is a plan view schematically showing a configuration of the conveyance apparatus600A. In this embodiment, the levitation unit is divided into two units, i.e., a first levitation unit10A and a second levitation unit10B, in order to convey a larger substrate100. For example, the substrate100is a glass substrate of a G10 size (3,130 mm×2,880 mm). Note that the configuration of the conveyance apparatus600A except for the first and second levitation unit10A and10B is similar to those of the first and second embodiments, and therefore the description thereof is omitted as appropriate.

There is a gap10C between the first and second levitation unit10A and10B. That is, the first and second levitation unit10A and10B are arranged across the gap10C. The first and second levitation unit10A and10B are disposed below the substrate100, which is the object to be processed, as in the case of the first and second embodiments. Further, the first and second levitation unit10A and10B air-levitate the substrate100by ejecting, i.e., blowing, a gas onto the bottom surface of the substrate100. Laser light is applied while the levitated substrate100is being moved. The irradiation area15aof the laser light has a line-like shape along the y direction. The irradiation area15ais formed in the first levitation unit10A.

InFIG.20, the holding mechanism12is moved along the x direction by the moving mechanism13(not shown inFIG.20). In the plan view, the conveyance direction of the substrate100is parallel to the x direction. The holding mechanism12moves along the gap10C. The holding mechanism12absorbs and holds the central part of the substrate100, instead of absorbing and holding the end thereof. In the plan view, the first levitation unit10A is disposed at a part of the substrate100extending from the central part of the substrate100to one end thereof. In the plan view, the second levitation unit10B is disposed at another part of the substrate100extending from the central part of the substrate100to the other end thereof.

InFIG.20, the first levitation unit10A is disposed on the −y side of the holding mechanism12, and the second levitation unit10B is disposed on the +y side of the holding mechanism12. Therefore, the first levitation unit10A air-levitates the part of the substrate100extending from the central part of the substrate100to the edge thereof on the −y side. The second levitation unit10B is air-levitated the other part of the substrate100extending from the central part of the substrate100to the edge thereof on the +y side. As described above, in this embodiment, the first and second levitation unit10A and10B, both of which air-levitate the central part of the substrate100, are provided. The holding mechanism12holds the inner part of the substrate100, instead of holding the end thereof.

As the holding mechanism12holds the central part of the substrate100, the substrate100can be reliably absorbed and held. This feature will be described with reference toFIG.21.FIG.21is a schematic diagram for explaining a case where the end of the substrate100is held.

When a rotational force around the z-axis is applied to the substrate100, a moment of inertia M (hereinafter also referred to as an inertial moment M) acts on the part held by the holding mechanism12. When the holding mechanism12is holding the end of the substrate100, the inertial moment M is larger than when the holding mechanism12is holding the central part of the substrate100. The larger the substrate100is, the larger the inertial moment M becomes. When the inertial moment M becomes large, there is a risk that the vacuum absorption of the holding mechanism12could be detached, i.e., the substrate100is detached from the holding mechanism12.

It is possible to increase the absorption force by increasing the width of the holding mechanism12in the y direction. However, when the width of the holding mechanism12is increased, the contact area between the substrate100and the holding mechanism12increases. Therefore, as shown inFIG.22, electrification, i.e., electrical charging, of the substrate100becomes problematic. For example, the substrate100is electrically charged by the absorption peeling electrification that occurs when the substrate100is adsorption-destructed (as shown in the upper part inFIG.22). The amount of electrical charging increases in proportion to the contact area between the substrate100and the holding mechanism12.

The holding mechanism12is formed of a metal material. It is possible to release the electric charge in the holding mechanism12by connecting the holding mechanism12to the ground. Meanwhile, the substrate100is made of an insulator such as glass. Therefore, the electric charge in the electrically charged substrate100remains in the substrate100. A Coulomb force occurs between the substrate100and the levitation unit10, causing the substrate100to be attracted toward the levitation unit10(as show in the lower part inFIG.22). In this case, there is a risk that the substrate100could come into contact with the levitation unit10, so that both of them could be damaged.

Therefore, in this embodiment, the holding mechanism12holds the central part of the substrate100, instead of holding the end thereof. By doing so, it is possible to reduce the inertial moment that occurs in the part held by the holding mechanism12, and thereby reduce the planar size of the holding mechanism12. That is, even when the planar size of the holding mechanism12is reduced, it is possible to prevent the absorption/holding of the substrate100from being detached (i.e., prevent the substrate100being detached from the holding mechanism12).

The holding mechanism12holds the central part of the substrate100, instead of holding the end thereof. That is, in the plan view, the second levitation unit10B is disposed over a part of the substrate100extending from the edge of the substrate100to the central part thereof. The central part of the substrate100can be defined as, for example, the place of the substrate100that bends and comes into contact with the second levitation unit10B in a state in which no gas is ejected from the second levitation unit10B. That is, if the ejection of the gas from the second levitation unit10B is stopped while the holding mechanism12is holding the central part of the substrate100and conveying the substrate100, the substrate100will come into contact with the second levitation unit10B. Further, the end of the substrate100can be defined, for example, as the place of the substrate100that does not come into contact with the second levitation unit10B even when the substrate100bends in a state in which no gas is ejected from the second levitation unit10B. Even if the ejection of the gas from the second levitation unit10B is stopped while the holding mechanism12is holding the end of the substrate100and conveying the substrate100, the substrate100does not come into contact with the second levitation unit10B.

In the conveyance method according to this embodiment, the substrate100is conveyed in order to apply laser light that forms a linear irradiation area15ato the substrate100. A part of the substrate100extending from the central part of the substrate100to a one end thereof in the plan view is levitated by using the first substrate levitation unit10A disposed below the substrate100, another part of the substrate100extending from the central part of the substrate100to the other end thereof in the plan view is levitated by using the second substrate levitation unit10B disposed below the substrate100. The substrate100is adsorbed and held by using the holding mechanism12disposed below the central part of the substrate100. In order to move the substrate100with respect to the irradiation place of the laser light15, the holding mechanism12is moved along the gap10C between the first and second levitation unit10A and10B.

Examples of the irradiation process according to this embodiment will be described hereinafter with reference toFIGS.23to25. Each ofFIGS.23to25schematically shows an irradiation places of laser light in a substrate100. In each ofFIGS.23to25, the substrate100is a mother glass substrate for forming a plurality of display panels. The substrate size is, for example, 3,130 mm x 2,880 mm.

An Example 1 shown inFIG.23is an example in which eight display panels P1to P8are manufactured from one substrate100. The length of the substrate in the x direction is 3,130 mm, and the length of the substrate in the y direction is 2,880 mm. The panel size of each display panel is 764 mm×1,341 mm. In this case, the length of the irradiation area15ain the y direction is 1,341 mm or larger. By applying laser light while conveying the substrate100in the x direction, substantially a half of the substrate100is irradiated with the laser light. In the area irradiated with the laser light, an amorphous silicon film is crystallized and a polysilicon film is formed. Further, by performing the irradiation process twice, the polysilicon film is formed over substantially the entire surface of the substrate100.

In the first irradiation process, substantially a half of the substrate100is irradiated with the laser light. That is, in the first irradiation process, a rectangular area corresponding to a half of the substrate100on a one end side thereof is irradiated with laser light. The area that will become the display panels P1to P4is irradiated with laser light. In the first irradiation process, the substrate100is conveyed in the x direction in a state in which the holding mechanism12(not shown inFIG.23) holds an area that will become at least one of the display panels P5to P8.

After the first irradiation process, the substrate100is rotated around the z-axis by 180°. In the second irradiation process, the remaining half of the substrate100is irradiated with the laser light. That is, in the second irradiation process, a rectangular area corresponding to a half of the substrate100on the other end side thereof is irradiated with laser light. The area that will become the display panels P5to P8is irradiated with laser light. In the second irradiation process, the substrate100is conveyed in the x direction in a state in which the holding mechanism12holds an area that will become at least one of the display panels P1to P4. Through the two irradiation processes, substantially the entire surface of the substrate100is irradiated with the laser light.

An Example 2 shown inFIG.24is an example in which six display panels P1to P6are manufactured from one substrate100. The length of the substrate in the x direction is 3,130 mm, and the length of the substrate in the y direction is 2,880 mm. The panel size of each display panel is 1,546 mm×888 mm. In this case, the size of the irradiation area15ain the y direction is 888 mm or larger. By applying laser light while conveying the substrate100in the x direction, substantially one third of the substrate100is irradiated with the laser light. In the area irradiated with the laser light, an amorphous silicon film is crystallized and a polysilicon film is formed. Further, by performing the irradiation process three times, the polysilicon film is formed over substantially the entire surface of the substrate100.

In the first irradiation process, substantially one third of the substrate100is irradiated with the laser light. A rectangular area corresponding to one third of the substrate100on a one end side thereof is irradiated with laser light. That is, the area that will become the display panels P1and P2is irradiated with laser light. In the first irradiation process, the substrate100is conveyed in the x direction in a state in which the holding mechanism12(not shown inFIG.24) holds an area that will become at least one of the display panels P3to P6.

After the first irradiation process, the substrate100is conveyed in the −y direction. In the second irradiation process, substantially one third of the substrate100located at the center is irradiated with laser light. In the second irradiation process, a rectangular area corresponding to one third of the substrate100including the center thereof is irradiated with laser light. The area that will become the display panels P3and P4is irradiated with laser light. In the third irradiation process, the substrate100is conveyed in the x direction in a state in which the holding mechanism12holds an area that will become at least one of the display panels P5and P6. Through the two irradiation processes, substantially two third of the substrate100is irradiated with laser light.

After the second irradiation process, the substrate100is rotated around the z-axis by 180° and conveyed in the y direction. In the third irradiation process, a rectangular area corresponding to one third of the substrate100on the other end side thereof is irradiated with laser light. The area that will become the display panels P5and P6is irradiated with laser light. In the third irradiation process, the substrate100is conveyed in the x direction in a state in which the holding mechanism12holds an area that will become at least one of the display panels P1to P4. Through the three irradiation processes, substantially the entire surface of the substrate100is irradiated with the laser light.

Note that the order of the laser-light irradiation processes is not limited to any particular order. For example, the area that will become the display panels P3and P4may be irradiated with laser light after irradiating the area that will become the display panels P5and P6with laser light. Further, in the first irradiation process, the area that will become the display panels P3and P4may be irradiated with laser light.

An Example 3 shown inFIG.25is an example in which three display panels P1to P3are manufactured from one substrate100. The length of the substrate in the x direction is 2,880 mm, and the length of the substrate in the y direction is 3,130 mm. The panel size of each display panel is 1,806 mm×1029 mm. In this case, the size of the irradiation area15ain the y direction is 1,029 mm or larger. By applying laser light while conveying the substrate100in the x direction, substantially one third of the substrate100is irradiated with the laser light. In the area irradiated with the laser light, an amorphous silicon film is crystallized and a polysilicon film is formed. Further, by performing the irradiation process three times, the polysilicon film is formed over substantially the entire surface of the substrate100.

In the first irradiation process, substantially one third of the substrate100is irradiated with the laser light. A rectangular area corresponding to one third of the substrate100on a one end side thereof is irradiated with laser light. That is, the area that will become the display panel P1is irradiated with laser light. In the first irradiation process, the substrate100is conveyed in the x direction in a state in which the holding mechanism12(not shown inFIG.25) holds an area that will become at least one of the display panels P1and P2.

After the first irradiation process, the substrate100is conveyed in the −y direction. In the second irradiation process, substantially one third of the substrate100located at the center is irradiated with laser light. In the second irradiation process, a rectangular area corresponding to one third of the substrate100including the center thereof is irradiated with laser light. The area that will become the display panel P2is irradiated with laser light. In the third irradiation process, the substrate100is conveyed in the x direction in a state in which the holding mechanism12holds an area that will become at least one of the display panels P1and P3. Through the two irradiation processes, substantially two third of the substrate100is irradiated with laser light.

After the second irradiation process, the substrate100is rotated around the z-axis by 180° and conveyed in the y direction. In the third irradiation process, a rectangular area corresponding to one third of the substrate100on the other end side thereof is irradiated with laser light. The area that will become the display panel P3is irradiated with laser light. In the third irradiation process, the substrate100is conveyed in the x direction in a state in which the holding mechanism12holds an area that will become at least one of the display panels P1and P2. Through the three irradiation processes, substantially the entire surface of the substrate100is irradiated with the laser light.

Note that the order of the laser-light irradiation processes is not limited to any particular order. For example, the area that will become the display panels P3and P4may be irradiated with laser light after irradiating the area that will become the display panels P5and P6with laser light. Further, in the first irradiation process, the area that will become the display panels P3and P4may be irradiated with laser light.

In the Examples 2 and 3, about one third of the area of the substrate100is irradiated with laser light in one irradiation process. Therefore, the holding mechanism12holds the substrate100at a place about one third of the substrate size away from the edge of the substrate100. That is, in the y direction, the second levitation unit10B has a width equivalent to about one third of the substrate size of the substrate100. Needless to say, the width of the second levitation unit10B is not limited to one third of the substrate size. The size of the second levitation unit10B may be determined by determining the number of times of processes according to the substrate size, the number of panels obtained from one substrate, and the size of the irradiation area15aof the laser light. For example, the size of each of the first and second levitation unit10A and10B may be one fourth of the substrate size or larger.

By the configuration according to this embodiment, it is possible appropriately convey a large substrate100. Even when a rotating force is applied to the substrate100, it is possible to prevent the absorption/holding of the substrate from being disengaged, i.e., prevent the substrate being disengaged from the holding mechanism due to the inertial moment. Further, it is possible to reliably hold the substrate100with a small absorption area, and thereby to prevent the increase in the amount of electrification, i.e., electrical charging. Therefore, it is possible to prevent the substrate100from coming into contact with the first levitation unit10A or the second levitation unit10B due to a Coulomb force.

Note that the configuration of the third embodiment can be combined with the configuration(s) of the first or/and second embodiment(s) as desired. For example, in the configuration of the third embodiment, the conveyance direction of the substrate100may be inclined from the longitudinal direction of the irradiation area15a.

A semiconductor device having the above-described polysilicon film is suitable for a TFT (Thin Film transistor) array substrate for an organic EL (Electro Luminescence) display. That is, the polysilicon film is used as a semiconductor layer including source regions, channel regions, and drain regions of TFTs.

A configuration in which a semiconductor device according to this embodiment is applied to an organic EL display will be described hereinafter.FIG.26is a simplified cross-sectional view of pixel circuits of an organic EL display. The organic EL display300shown inFIG.26is an active matrix-type display device in which a TFT(s) is disposed in each pixel PX.

The organic EL display device300includes a substrate310, a TFT layer311, an organic layer312, a color filter layer313, and a sealing substrate314.FIG.26shows a top-emission-type organic EL display device, in which the side of the sealing substrate314is located on the viewing side. Note that the following description is given to show an example of a configuration of an organic EL display device and this embodiment is not limited to the below-described configuration. For example, a semiconductor device according to this embodiment may be used for a bottom-emission-type organic EL display device.

The substrate310is a glass substrate or a metal substrate. The TFT layer311is provided over the substrate310. The TFT layer311includes TFTs311adisposed in the respective pixels PX. Further, the TFT layer311includes wiring lines (not shown) or the like connected to the TFTs311a. The TFTs311a, the wiring, and the like constitute pixel circuits.

The organic layer312is provided over the TFT layer311. The organic layer312includes an organic EL light-emitting element312adisposed in each pixel PX. Further, in the organic layer312, separation walls312bfor separating organic EL light-emitting elements312aare provided between pixels PX.

The color filter layer313is provided over the organic layer312. The color filter layer313includes color filters313afor performing color displaying. That is, in each pixel PX, a resin layer colored in R (red), G (green), or B (blue) is provided as the color filter313a.

The sealing substrate314is provided over the color filter layer313. The sealing substrate314is a transparent substrate such as a glass substrate and is provided to prevent deterioration of the organic EL light-emitting elements of the organic layer312.

Electric currents flowing through the organic EL light-emitting elements312aof the organic layer312are changed by display signals supplied to the pixel circuits. Therefore, it is possible to control an amount of light emitted in each pixel PX by supplying a display signal corresponding to a display image to each pixel PX. As a result, it is possible to display a desired image.

In an active matrix-type display device such as an organic EL display, at least one TFT (e.g., a switching TFT or a driving TFT) is provided in one pixel PX. Further, a semiconductor layer including a source region, a channel region, and a drain region is provided in the TFT in each pixel PX. A polysilicon film according to this embodiment is suitable for a semiconductor layer of TFTs. That is, by using a polysilicon film manufactured by the above-described manufacturing method for a semiconductor layer of a TFT array substrate, it is possible to prevent or reduce in-plane variations of TFT characteristics. Therefore, it is possible to manufacture display devices having excellent display characteristics with high productivity.

(Method for Manufacturing Semiconductor Device)

The method for manufacturing a semiconductor device by using a laser irradiation apparatus according to this embodiment is suitable for manufacturing of a TFT array substrate. A method for manufacturing a semiconductor device including a TFT will be described with reference toFIGS.27and28. Each ofFIGS.27and28is a cross-sectional view showing a step in a method for manufacturing a semiconductor device. In the following description, a method for manufacturing a semiconductor device including an inverted staggered-type TFT will be described. Each ofFIGS.27and28shows one of the steps for forming a polysilicon film in a method for manufacturing a semiconductor. Note that other manufacturing steps can be performed by using known techniques, and therefore descriptions thereof are omitted as appropriate.

As shown inFIG.27, a gate electrode402is formed over a glass substrate401. A gate insulating film403is formed over the gate electrode402. An amorphous silicon film404is formed over the gate insulating film403. The amorphous silicon film404is disposed so as to be placed over the gate electrode402with the gate insulating film403interposed therebetween. For example, the gate insulating film403and the amorphous silicon film404are successively formed by a CVD (Chemical Vapor Deposition) method.

Then, by irradiating the amorphous silicon film404with laser light L1, a polysilicon film405is formed as shown inFIG.28. That is, the amorphous silicon film404is crystallized by the laser irradiation apparatus1shown inFIG.1or the like. As a result, a polysilicon film405that is formed as silicon is crystallized is formed over the gate insulating film403. The polysilicon film405corresponds to the above-described polysilicon film101b.

Further, the above descriptions are given on the assumption that a laser annealing apparatus according to this embodiment is one in which a polysilicon film is formed by applying laser light to an amorphous silicon film. However, the present disclosure may be applied to other cases in which a micro-crystalline film is formed by applying laser light to an amorphous silicon film. Further, the laser light used for the annealing is not limited to Nd:YAG laser. Further, a method according to this embodiment can also be applied to a laser annealing apparatus for crystallizing a thin film other than the silicon film. That is, the method according to this embodiment can be applied to any laser annealing apparatus in which a crystallized film is formed by applying laser light to an amorphous film. According to the laser annealing apparatus in accordance with this embodiment, it is possible to appropriately reform (or modify) a substrate including a crystallized film.

First Modified Example

Next, a laser irradiation apparatus using a conveyance apparatus according to a first modified example will be described with reference toFIG.29.FIG.29is a plan view schematically showing a laser irradiation apparatus1. The fundamental configurations of the conveyance apparatus and the laser irradiation apparatus1are similar to those of the first embodiment, and therefore descriptions thereof are omitted as appropriate.

In the modified example, in the plan view, the angle of the object to be processed16is different from that in the first embodiment. Specifically, an edge161on the −y side of the object to be processed16is inclined from the conveyance direction. That is, the conveyance direction and the edge161are not parallel to each other. InFIG.29, the object to be processed16is rotated around the Z-axis from the configuration shown inFIG.1. The angle formed by the edge161of the object to be processed16to the y direction is represented by φ. Further, the angle between the x direction and the conveyance direction is represented by θ. Although φ is larger than θ in this example, φ may be equal to or smaller than θ.

The angle φ is preferably larger than 0° and not larger than 5°. The angle θ is preferably larger than 0° and not larger than 5°. The angle φ can be adjusted according to the specifications of the laser irradiation process. For example, in the conveyance apparatus600shown inFIGS.6to14described in the second embodiment, the alignment mechanism69acan change the angle of the substrate100to a desired angle. That is, as shown inFIG.9, the alignment mechanism69afunctions as a driving mechanism that rotates around the Z-axis. The alignment mechanism69asets the angle of the edge of the substrate100to an angle different from the conveyance direction. By doing so, it is possible to rotate the substrate100around the Z-axis before irradiating it with laser light. The conveyance apparatus600can convey the substrate100while keeping it at the desired angle relative to the line-shaped laser light. After irradiation with the laser light, as shown inFIG.11, the alignment mechanism69brotates the substrate100disposed over the levitation unit10. By doing so, the edge of the substrate100becomes parallel to the X direction as shown inFIG.12.

Second Modified Example

A laser irradiation apparatus according to a second modified example will be described with reference toFIG.30. A laser irradiation apparatus1according to the second modified example includes a slit mechanism30.

As shown inFIG.30, in an object to be processed16having a rectangular shape, an edge on the +x side is referred to as an edge162; an edge on the −x side is referred to as an edge163; and an edge on the +y side is referred to as an edge164. In the Irradiation Example 1, similarly toFIG.29, the conveyance direction is inclined from the edges161and164of the object to be processed16.

An Irradiation Example in which the entire surface of the object to be processed16is irradiated with laser light in two laser irradiation steps will be described. In the object to be processed16, laser light is applied to areas168and169one by one. Specifically, the area168, which is one half of the object to be processed16, is irradiated with laser light during the first conveyance. The area168is an area surrounded by the edges162,163and161, and a boundary line165. The boundary line165is a straight line parallel to the conveyance direction.

Next, after the object to be processed16is rotated 180° around the Z-axis, the second conveyance is performed. By doing so, the area169, which is the remaining one half of the object to be processed, is irradiated with laser light. That is, a polysilicon film is formed in the area168in the first laser irradiation, and a polysilicon film is also formed in the area169in the second laser irradiation. The area169is an area surrounded by the edges162,163and164, and the boundary line165. Note that the areas168and169may partially overlap each other. In this case, an area on and near the boundary line165of the object to be processed16is irradiated with laser light twice. Alternatively, a gap may be provided between the area168, to which laser light is applied in the first irradiation, and the area169, to which laser light is applied in the second irradiation. In this case, there is an area between the area168, which is irradiated in the first irradiation, and the area169, which is irradiated in the second irradiation, in which no laser light is applied. Further, the gap between the areas168and169may be made as narrow as possible. The boundary line that defines the area168, which is irradiated in the first irradiation, and the boundary line that defines the area169, which is irradiated in the second irradiation, do not coincide with each other.

The slit mechanism30can adjust the length of the laser light irradiation area15ain the object to be processed16. That is, the slit mechanism30is a variable-length slit having a variable slit length. In this way, the sizes of the areas168and169, which are irradiated in the first and second laser irradiation steps, respectively, can be freely changed. Specifically, the slit mechanism30can change the length of the linear irradiation area15ain the y direction by adjusting its slit length. For example, the slit mechanism30is provided in the optical system of the laser irradiation unit14shown inFIG.2.

The slit mechanism30includes a light-shielding part32and a light-shielding part33. Each of the light-shielding parts33and32has a light-shielding plate or the like that is movably provided along the y direction. The light-shielding parts33and32can block the ends of the line-shaped laser light. The light-shielding part33blocks the end on the −y side of the line beam. That is, the light-shielding part33defines the position of the linear irradiation area15aon the −y side. The light-shielding part32blocks the end on the +y side of the line beam. That is, the light-shielding part32defines the position of the linear irradiation area15aon the +y side. Therefore, the position of the light-shielding part32defines the position of the boundary line165.

It is possible to reduce the slit length by moving the light-shielding parts32and33so that they get close to each other in the y direction. It is possible to increase the slit length by moving the light-shielding parts32and33so that they recede from each other in the y direction.

Although the light-shielding parts32and33are provided in the laser irradiation unit14, in the following description, the positions of the light-shielding parts32and33are indicated by the positions when they are projected onto the object to be processed16by the optical system for simplifying the explanation. For example, in the following description, it is assumed that the position of the light-shielding part32corresponds to the end of the irradiation area15aon the +y side, and the position of the light-shielding part33corresponds to the end of irradiation area15aon the −y side.

The light-shielding parts33and32move independently of each other. In this way, the slit mechanism30can change the length of the line beam and the irradiation end positions in the object to be processed16. Further, the light-shielding parts33and32may be moved in an interlocked manner with the conveyance of the object to be processed16. That is, the positions of the light-shielding parts32and33may be changed according to the change in the position of the object to be processed16during the conveyance. Note that, although the conveyance direction is inclined from the edge161of the object to be processed16inFIG.30as in the case ofFIG.29, the conveyance direction may be parallel to the edge161as shown inFIG.1.

An Irradiation Example 1 will be described with reference toFIG.31.FIG.31shows plan views schematically showing a laser light irradiation area15ain the object to be processed16. In the below-shown drawings, the conveyance unit11and the levitation unit10are omitted as appropriate for simplifying the explanation. In the Irradiation Example 1, similarly toFIG.1, the edges161and164of the object to be processed16are parallel to the conveyance direction. The boundary line165between the areas169and168is parallel to the conveyance direction and the edge161.

A configuration at an irradiation start point at which the first irradiation starts is shown on the left side ofFIG.31, and a configuration at an irradiation end point at which the first irradiation ends is shown on the right side ofFIG.31. Note that the irradiation start point means a timing at which the irradiation area15aoverlaps (e.g., coincides with) the edge162of the object to be processed16by the conveyance. The irradiation end point means a timing at which the irradiation area15apasses through the edge163on the −x side of the object to be processed16by the conveyance.

During the first irradiation, the positions of the light-shielding parts32and33are fixed. The slit length and the irradiation end positions are fixed from the irradiation start point to the irradiation end point. The position of the light-shielding part33has been adjusted so that the end position of the irradiation area15aon the −y side coincides with the edge161. That is, the light-shielding part33forms a line beam so that one end of the irradiation area15acoincides with the edge161.

The area168is irradiated with laser light by the conveyance of the object to be processed16. When the irradiation is finished, a polysilicon film16ais formed in the area168. When the laser irradiation to the area168is finished, the object to be processed16is rotated 180° around the Z-axis and it is irradiated with laser light in a similar manner (not shown). As a result, the laser irradiation to the area169is completed.

It is possible to reduce the amount of laser light applied to areas outside the substrate, i.e., areas outside the object to be processed16. For example, in the Irradiation Example 1, the laser light is applied to triangular areas170schematically shown inFIG.31. The areas170are areas showing the trajectory of the laser light that is not applied to the object to be processed16when the object to be processed16is conveyed. InFIG.31and the like, for the sake of explanation, the trajectory along which the area that is located outside the object to be processed16but is irradiated with the laser light moves as the object to be processed16is conveyed is shown as the areas170. Note that, in practice, the laser light is applied to a fixed position in the levitation unit10(see the irradiation area15ashown inFIG.1or6or the like). In this case, the laser light irradiation area15ais formed in the gap between the two precision levitation units111. By adjusting the position of the light-shielding part32, it is possible to make the boundary line165between the areas169and168coincide with an area where no device is formed in the object to be processed16. For example, the boundary line165can be formed on a cutting line of the object to be processed16. In this way, it is possible to prevent variations in irradiation in the device.

An Irradiation Example 2 will be described with reference toFIGS.32and33.FIGS.32and33are plan views schematically showing a laser light irradiation area15ain an object to be processed16. In the Irradiation Example 2, light-shielding parts32and33move according to the conveyance of the object to be processed16.FIG.32shows how the edge162of the object to be processed16is irradiated with laser light. That is,FIG.32shows the movement of the light-shielding part33at the start of the irradiation to the object to be processed16.FIG.33shows how the edge163of the object to be processed16is irradiated with laser light. That is,FIG.33shows the movement of the light-shielding part32at the end of the irradiation to the object to be processed16. In the Irradiation Example 2, the edge161of the object to be processed16is parallel to the conveyance direction.

Firstly, the movement of the light-shielding part33at the start of the irradiation will be described with reference toFIG.32. The position of the light-shielding part33at a movement start point is shown on the left side ofFIG.32, and the position thereof at a movement end point is shown on the right side ofFIG.32. InFIG.32, the position of the light-shielding part32is fixed.

The light-shielding part33moves in the −y direction so as to coincide with the position of the end of the object to be processed16on the +x side. During the conveyance of the object to be processed16, the light-shielding part33moves along the edge162in the plan view. As a result, a polysilicon film16ais formed on the −x side of the edge161over the entire edge161.

Specifically, while the irradiation area15acrosses the edge162of the object to be processed16, the light-shielding part33moves in the −y direction. The light-shielding part33moves to the edge161of the object to be processed16so that the laser light is applied to the entire area168. That is, the light-shielding part33gradually moves away from the light-shielding part32. Therefore, the irradiation area15agradually becomes longer according to the movement of the light-shielding part33. After the light-shielding part33has moved to the position at the movement end point inFIG.32, the position of the light-shielding part33is fixed while the object to be processed16is being conveyed.

Next, the movement of the light-shielding part32at the end of the irradiation will be described with reference toFIG.33. The position at the movement start point of the light-shielding part32is shown on the left side ofFIG.33, and the position at the movement end point of the light-shielding part32is shown on the right side ofFIG.33. InFIG.33, the position of the light-shielding part33is fixed.

The light-shielding part32moves in the −y direction so as to coincide with the position of the end of the object to be processed16on the −x side. During the conveyance of the object to be processed16, the light-shielding part33moves along the edge163in the plan view. Specifically, while the irradiation area15acrosses the edge163of the object to be processed16, the light-shielding part32moves in the −y direction. The light-shielding part32gradually moves closer to the light-shielding part33. Therefore, the irradiation area15agradually becomes shorter according to the movement of the light-shielding part32.

In this way, since the area168is irradiated with laser light, the polysilicon film16ais formed over the entire area168. When the laser irradiation to the area168is finished, the object to be processed16is rotated 180° around the Z-axis and it is irradiated with laser light in a similar manner. As a result, the laser irradiation to the area169is completed. In the Irradiation Example 2, the irradiated area outside the object to be processed16can be reduced. Therefore, damage to the levitation unit10can be reduced.

An Irradiation Example 3 will be described with reference toFIG.34.FIG.34is a plan view schematically showing a laser light irradiation area15ain an object to be processed16. A configuration at the irradiation start point is shown on the left side ofFIG.34, and a configuration at the irradiation end point is shown on the right side thereof. The position of the light-shielding part33in the Irradiation Example 3 differs from that in the Irradiation Example 1. More specifically, the light-shielding part33is disposed so that one end of the irradiation area15ais positioned on the −y side of the edge161of the object to be processed16. In the Irradiation Example 3, the conveyance direction is parallel to the edge161. The positions of the light-shielding parts32and33are fixed.

In the plan view, it is formed so that one end of the irradiation area15aprotrudes from the edge161to the −y side thereof. Note that in the Irradiation Example 3, an area170which protrudes beyond the object to be processed16to the −y side thereof is also irradiated with laser light. It is possible to reliably irradiate the object to be processed16including the edge161thereof on the −y side with laser light. Therefore, the laser light can be uniformly applied even on and near the edge161.

An Irradiation Example 4 will be described with reference toFIGS.35and36. Each ofFIGS.35and36is a plan view schematically showing an object to be processed16and a laser light irradiation area15a.FIG.35schematically shows a configuration before the start of the irradiation, andFIG.36schematically shows a configuration after the end of the irradiation. In the Irradiation Example 4, the position of the light-shielding part32gradually changes during the conveyance of the object to be processed16. Note that in the Irradiation Example 4, the conveyance direction is inclined from the edge161.

Firstly, with reference toFIG.35, points in the object to be processed16and their trajectories are defined as follows. As shown inFIG.35, the intersection between the edge162and the boundary line165is defined as a point C1. The intersection between the edge163and the boundary line165is defined as a point C2. The intersection between the edge162and the edge161is defined as a point C3. The intersection between the edge163and the edge161is defined as a point C4. The points C3and C4correspond to corners of the object to be processed16having a rectangular shape.

The trajectories of the points C1to C4during the conveyance are represented by trajectories T1to T4, respectively. For example, when the object to be processed16is conveyed in the conveyance direction, the point C1moves along the trajectory T1. Each of the trajectories T1to T4is a straight line parallel to the conveyance direction. In the plan view, from the +y side, they are arranged in the order of trajectories T2, T1, T4and T3. Further, similarly to the Irradiation Example 3, one end of the irradiation area15ais positioned on the −y side of the edge161of the object to be processed16. That is, the position of the light-shielding part33is adjusted so that the irradiation area15aprotrudes from the edge161to the −y side thereof.

In the Irradiation Example 4, when the object to be processed16is conveyed along the conveyance direction, it is brought into a state shown inFIG.36. InFIG.36, an area168on the −y side of the boundary line165is irradiated with laser light. While the object to be processed16is being conveyed, the light-shielding part32moves according to the conveyance. Specifically, when the conveyance speed is fixed, the light-shielding part32moves at a constant speed. The light-shielding part32gradually moves in the +y direction at the constant moving speed. The light-shielding part32moves so that a line connecting the points C1and C2coincides with the boundary line165. Therefore, it is possible to make the boundary line165and the edge161parallel to each other even when the edge161is inclined from the conveyance direction. In other words, the boundary line165coincides with a straight line extending in a direction inclined from the conveyance direction.

Further, the irradiation area15aprotrudes beyond the trajectory T3to −y side thereof. Therefore, the laser light is also applied to the area170protruding beyond the object to be processed16to −y side thereof. Note that although the light-shielding part33is not moved so that the slit length changes according to the conveyance in the Irradiation Example 4, it may be moved so that the slit length changes according to the conveyance. That is, the slit length may be fixed or may be changed.

An Irradiation Example 5 will be described with reference toFIGS.37and38. Each ofFIGS.37and38is a plan view schematically showing a configuration in the Irradiation Example 5.FIG.37schematically shows a configuration before the start of the irradiation, andFIG.38schematically shows a configuration after the end of the irradiation. In the Irradiation Example 5, the light-shielding parts32and33move according to the conveyance. In the Irradiation Example 5, the light-shielding part33is moved in +y direction according to the conveyance.

In the Irradiation Example 5, the position of the light-shielding part33changes along the edge161according to the conveyance. Further, similarly to the Irradiation Example 4, the position of the light-shielding part32changes along the boundary line165parallel to the edge161according to the conveyance. Therefore, the light-shielding parts33and32gradually move in the +y direction at the same moving speed. The slit length of the slit mechanism30is fixed. The line length of the irradiation area15acoincides with the distance from the edge161to the boundary line165in the y direction. In this way, it is possible to prevent the area protruding beyond the object to be processed16to the −y side thereof from being irradiated with the laser light. Therefore, a polysilicon film16ais formed in the area168.

Other Embodiment

A holding mechanism capable of performing vacuum absorption with or without a valve may be used as the holding mechanism12for holding the object to be processed16or the substrate100. Further, an inert gas such as compressed air or nitrogen can be used as a gas for levitating the object to be processed16or the substrate100.

Although the second embodiment has been described on the assumption that the levitation unit10includes the precision levitation unit111, the semi-precision levitation unit112, and the rough levitation unit113, the levitation unit10does not have to include all of the precision levitation unit111, the semi-precision levitation unit112, and the rough levitation unit113. That is, the levitation unit10may include at least one of the precision levitation unit111, the semi-precision levitation unit112, and the rough levitation unit113. For example, the levitation unit10may include only two levitation units, e.g., a precision levitation unit111and a rough levitation unit113. In this case, the rough levitation unit113is disposed adjacent to the precision levitation unit111.

Further, in the conveyance apparatus600shown inFIGS.6to14, it is possible to successively irradiate a plurality of substrates with laser light. An example in which the conveyance apparatus600levitates and conveys two substrates100and101simultaneously will be described with reference toFIGS.39to42. Note that descriptions of details of the conveyance apparatus600that are substantially the same as those described in the second embodiment will be omitted as appropriate.

As shown inFIG.39, during the laser irradiation of the first substrate100, the second substrate101is carried into the fourth area60dof the levitation unit10. InFIG.39, laser light is applied to the substrate100in the state in which the edge of the substrate100is inclined from the Y direction. Then, when the conveyance unit11bhas conveyed the substrate100to the second area60b, the first laser irradiation to the substrate100is finished.

When the laser irradiation to the substrate100is finished, the alignment mechanism69brotates the substrate100as shown in FIG.40. As a result, the edges of the substrate100becomes parallel to the X and Y directions, respectively. At this point, the conveyance unit11aconveys the substrate101in the +Y direction. Therefore, the substrate101, which had been disposed in the fourth area60dinFIG.39, has been moved to the first area60ainFIG.40. That is, the conveyance of the substrate101by the conveyance unit11aand the conveyance of the substrate100by the conveyance unit11bare performed simultaneously with each other.

Then, after the alignment mechanism69arotates the substrate101, the conveyance unit11bconveys the substrate101. As a result, as shown inFIG.41, the substrate101passes through the irradiation area15ain the state in which the edge of the substrate101is inclined from the Y direction. At this point, the conveyance unit11chas already conveyed the substrate100in the −Y direction. Therefore, the substrate100, which had been disposed in the second area60binFIG.40, has been moved to the third area60cinFIG.41. That is, the conveyance of substrate101by the conveyance unit11band the conveyance of the substrate100by the conveyance unit11care performed simultaneously with each other. Then, when the substrate101has been conveyed to the second area60b, the first laser irradiation to the substrate101is finished.

When the laser irradiation to the substrate101is finished, the alignment mechanism69brotates the substrate101. As a result, as shown inFIG.42, the edges of the substrate101become parallel to the X and Y directions, respectively. At this point, the conveyance unit11dhas already conveyed the substrate100in the −X direction. Therefore, the substrate100, which had been disposed in the third area60cinFIG.41, has been moved to the fourth area60dinFIG.42. That is, while the alignment mechanism69bis rotating the substrate101, the conveyance unit11dconveys the substrate100.

Further, in the fourth area60d, the rotation mechanism68rotates the substrate100by 180° as shown inFIG.42. Then, the above-described processes are repeated for the substrates101and100. That is, the processes shown inFIGS.39to42are performed after the substrates101and100are interchanged. Therefore, in the second laser irradiation, the areas that have not been irradiated with laser light in the first laser irradiation are irradiated with laser light. That is, one half of the substrate100is irradiated with laser light in the first laser irradiation, and the remaining one half of the substrate100is irradiated with laser light in the second laser irradiation.

By doing so, the conveyance apparatus600can simultaneously convey a plurality of substrates100and101, which are in a levitated state. The conveyance unit11ato11dmake the substrates100and101successively move in a circular manner. As a result, the two substrates100and101pass through the irradiation area15ain a successive manner. It is possible to continuously irradiate a plurality of substrates with laser light. Further, the waiting time for carrying in or carrying out substrates to or from the conveyance apparatus600can be reduced. As a result, it is possible to reduce the takt time (the cycle time) and thereby improve the productivity. Needless to say, the number of substrates the conveyance apparatus600levitates at the same time is not limited to two, but may be three or more.

Note that the present disclosure is not limited to the above-described embodiments, and they can be modified as appropriate without departing from the scope and spirit of the disclosure.

This application is based upon and claims the benefit of priority from Japanese patent application No. 2021-12922, filed on Jan. 29, 2021, the disclosure of which is incorporated herein in its entirety by reference.

REFERENCE SIGNS LIST