Laser annealing apparatus and method of manufacturing a substrate having a polysilicon layer

Abstract

The present disclosure provides a laser annealing apparatus and a method of manufacturing a substrate having a polysilicon layer. The laser annealing apparatus includes a laser beam source that emits a linearly polarized laser beam, a polygon mirror that rotates around a rotation axis and reflects the linearly polarized laser beam emitted from the laser beam source, a first Kerr cell disposed on a laser beam path between the laser beam source and the polygon mirror, and a first optical element that guides the linearly polarized laser beam reflected by the polygon mirror toward an amorphous silicon layer, wherein the linearly polarized laser beam is irradiated onto the amorphous silicon layer.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority and benefit to Korean Patent Application No. 10-2019-0092661, filed on July 30, 2019, with the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. Technical Field

[0003] One or more embodiments relate to laser annealing apparatus and methods for manufacturing substrates with polycrystalline silicon layers using laser annealing apparatus, and to laser annealing apparatus and methods for manufacturing substrates with polycrystalline silicon layers using laser annealing apparatus that can obtain previously expected results (such as uniform annealing of amorphous silicon layers and subsequent uniform polycrystalline silicon layers) even when the shape of a constituent element is inaccurate. Background Technology

[0004] Typically, display devices such as liquid crystal displays (LCDs) or organic light-emitting displays (OLEDs) use thin-film transistors (TFTs) to control the light emission of each pixel. When the TFTs comprise polycrystalline silicon, the manufacturing process of the display device may include forming a polycrystalline silicon layer on a substrate. The polycrystalline silicon layer can be formed by forming an amorphous silicon layer on the substrate and then annealing it. Annealing can be performed by irradiating the amorphous silicon layer with a laser beam.

[0005] In laser annealing equipment according to related technologies, when the shape of the optical element positioned in the optical path of the laser beam is incorrect, the final optical path of the laser beam differs from the preset optical path. Therefore, defects may occur when annealing of the amorphous silicon layer is performed differently than expected.

[0006] It will be understood that this background section is intended in part to provide useful background for understanding the technology. However, this background section may also include ideas, concepts, or knowledge that were known or understood by a person skilled in the art prior to the corresponding valid submission date of the subject matter disclosed herein. Summary of the Invention

[0007] One or more embodiments include a laser annealing apparatus that can achieve previously expected results even when the shape of a constituent element is incorrect, and a method for manufacturing a substrate having a polycrystalline silicon layer using the laser annealing apparatus. However, the above objectives are not limiting, and the scope of this disclosure is not limited thereto.

[0008] Additional aspects will be set forth in part in the following description, and will be partly apparent from the description, or may be learned by practicing embodiments of the present disclosure.

[0009] According to one or more embodiments, a laser annealing apparatus may include: a laser beam source emitting a linearly polarized laser beam; a polygonal mirror rotating about a rotation axis and reflecting the linearly polarized laser beam emitted from the laser beam source; a first Kerr cell disposed on the laser beam path between the laser beam source and the polygonal mirror; and a first optical element guiding the linearly polarized laser beam reflected by the polygonal mirror toward an amorphous silicon layer, wherein the linearly polarized laser beam irradiates the amorphous silicon layer.

[0010] The multifaceted mirror may include a first reflective surface and a second reflective surface. A first potential difference is applied to the first Kerr cell while the linearly polarized laser beam emitted from the laser beam source is incident on the first reflective surface, and a second potential difference is applied to the first Kerr cell while the linearly polarized laser beam emitted from the laser beam source is incident on the second reflective surface. The first potential difference may be different from the second potential difference.

[0011] The faceted mirror may include a first reflective surface and a second reflective surface, and while the faceted mirror rotates and the linearly polarized laser beam emitted from the laser beam source is incident on the second reflective surface, the second potential difference applied to the first Kerr cell may change.

[0012] The linear polarization direction of the linearly polarized laser beam emitted from the laser beam source can be in a plane parallel to the direction of the electric field generated in the first Kerr cell and including the linear path of the laser beam incident on the first Kerr cell, and the linear polarization direction can be perpendicular to the linear path of the linearly polarized laser beam incident on the first Kerr cell.

[0013] The laser annealing apparatus may further include a second optical element disposed in the laser beam path between the first Kerr cell and the polygon mirror. The second optical element ensures that the incident point of the linearly polarized laser beam on the polygon mirror after passing through the first Kerr cell is the same as the incident point of the linearly polarized laser beam emitted from the laser beam source on the polygon mirror when the first Kerr cell is not disposed between the laser beam source and the polygon mirror. Furthermore, the direction of the electric field generated in the first Kerr cell may be perpendicular to the rotation axis of the polygon mirror.

[0014] The laser annealing apparatus may further include: a second Kerr cell disposed on the laser beam path between the first Kerr cell and the polygon mirror; and a half-wave (λ / 2) plate disposed on the laser beam path between the second Kerr cell and the first Kerr cell, wherein the direction of the electric field generated in the second Kerr cell is perpendicular to the direction of the electric field generated in the first Kerr cell.

[0015] The first optical element may include: a first mirror having a convex reflective surface and a second mirror having a concave reflective surface.

[0016] The second optical element may include a first lens protruding toward the polygonal mirror and a second lens protruding toward the second Kerr cell.

[0017] One or more embodiments include a method of manufacturing a substrate having a polycrystalline silicon layer, the method comprising: forming an amorphous silicon layer on the substrate; and irradiating the amorphous silicon layer with a linearly polarized laser beam after the beam passes through a first Kerr cell, is reflected by a polygonal mirror rotating about a rotation axis, and is projected onto a first optical element.

[0018] The method may further include: rotating the polygonal mirror while moving the substrate in a predetermined direction.

[0019] In the process of irradiating the amorphous silicon layer with the linearly polarized laser beam, a first potential difference is applied to the first Kerr cell while the linearly polarized laser beam is incident on the first reflective surface of the polygonal mirror, and a second potential difference is applied to the first Kerr cell while the linearly polarized laser beam is incident on the second reflective surface of the polygonal mirror, wherein the first potential difference and the second potential difference are different from each other.

[0020] During the irradiation by the linearly polarized laser beam, the linearly polarized laser beam can be irradiated onto the amorphous silicon layer by changing the second potential difference applied to the first Kerr cell while the polygon mirror is rotating and the linearly polarized laser beam is incident on the second reflective surface of the polygon mirror.

[0021] In the irradiation by the linearly polarized laser beam, the linearly polarized laser beam having a linear polarization direction can be irradiated onto the amorphous silicon layer through the first Kerr cell, wherein the linear polarization direction can be in a plane parallel to the direction of the electric field generated in the first Kerr cell and including the linear path of the linearly polarized laser beam incident on the first Kerr cell, and the linear polarization direction can be perpendicular to the linear path of the linearly polarized laser beam incident on the first Kerr cell.

[0022] During the irradiation by the linearly polarized laser beam, the linearly polarized laser beam can irradiate the amorphous silicon layer through a second optical element passing between the first Kerr cell and the polygon mirror, and the second optical element makes the incident point of the linearly polarized laser beam on the polygon mirror after passing through the first Kerr cell the same as the incident point of the linearly polarized laser beam on the polygon mirror when the first Kerr cell is not placed between the laser beam source and the polygon mirror.

[0023] During the illumination by the linearly polarized laser beam, the direction of the electric field generated in the first Kerr cell can be perpendicular to the rotation axis of the polygonal mirror.

[0024] During the irradiation by the linearly polarized laser beam, the beam passes sequentially through the first Kerr cell, the half-wave (λ / 2) plate, and the second Kerr cell to be incident on the faceted mirror. The linearly polarized laser beam irradiates the amorphous silicon layer, and the direction of the electric field generated in the second Kerr cell is perpendicular to the direction of the electric field generated in the first Kerr cell. Attached Figure Description

[0025] The above and other aspects, features, and advantages of embodiments of the present disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings, in which:

[0026] Figure 1 This is a schematic diagram of a laser annealing apparatus according to an embodiment;

[0027] Figure 2 It is shown in Figure 1 A schematic diagram showing the change in the path of the laser beam in the constituent elements;

[0028] Figure 3 Is as Figure 1 A schematic perspective view of the multifaceted mirrors that form the components;

[0029] Figure 4 This is a schematic diagram of the trajectory of a laser beam illuminating an amorphous silicon layer when the shape of an optical element positioned or placed in the optical path of the laser beam is incorrect.

[0030] Figure 5 Is when using Figure 1 A schematic diagram of the trajectory of the laser beam irradiating the amorphous silicon layer when the laser annealing equipment corrects errors;

[0031] Figure 6 This is a schematic diagram of the trajectory of a laser beam illuminating an amorphous silicon layer when the shape of an optical element positioned or placed in the optical path of the laser beam is incorrect.

[0032] Figure 7 Is when using Figure 1A schematic graph showing the change in the intensity of the electric field applied to a constituent element over time when the laser annealing equipment corrects errors.

[0033] Figure 8 This is a schematic perspective view of a portion of a laser annealing apparatus according to an embodiment;

[0034] Figure 9 This is a schematic diagram of a portion of a laser annealing apparatus according to an embodiment; and

[0035] Figure 10 This is a flowchart of a method for manufacturing a substrate with a polycrystalline silicon layer. Detailed Implementation

[0036] Now, reference will be made to embodiments illustrated in the accompanying drawings. In this regard, embodiments may take different forms and should not be construed as limited to the description set forth herein. Therefore, embodiments are described below with reference to the accompanying drawings to explain aspects of that description. As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. Throughout this disclosure, the expression “at least one of a, b, and c” means only a, only b, only c, both a and b, both a and c, both b and c, all a, b, and c, or variations thereof.

[0037] The present disclosure will now be described more fully with reference to the accompanying drawings, in which embodiments of the present disclosure are illustrated. Throughout the drawings, the same reference numerals refer to the same elements, and redundant descriptions thereof have been omitted.

[0038] In the following embodiments, it will be understood that when a component such as a layer, film, region, or plate is referred to as being "on" another component, the component may be directly on said other component, or an intermediate component may be present on it. Furthermore, for ease of illustration and clarity, the dimensions of the components in the figures may be exaggerated. For example, since the dimensions and thicknesses of the components in the figures are arbitrarily shown for ease of illustration, the following embodiments are not limited thereto.

[0039] In the following examples, X, Y, and Z are not limited to the three axes of a Cartesian coordinate system and can be interpreted in a broader sense. For example, X, Y, and Z can be perpendicular to each other, or they can represent different directions that are not perpendicular to each other.

[0040] The terms "overlapping" or "overlapping" mean that the first object may be above, below, or to the side of the second object, or vice versa. Additionally, the term "overlapping" can include layering, stacking, facing or oriented, extending above, covering or partially covering, or any other suitable terminology as will be understood and appreciated by those skilled in the art. The terms "facing" and "oriented" mean that the first element may be directly or indirectly opposite the second element. Where a third element is located between the first and second elements, the first and second elements can be understood as being indirectly opposite each other, although still facing each other. When an element is described as "non-overlapping" or "non-coincident" with another element, this can include elements spaced apart from each other, offset from each other, or deviated from each other, or any other suitable terminology as will be understood and appreciated by those skilled in the art.

[0041] It will be understood that although various elements may be described herein using terms such as “first,” “second,” or “third,” these elements should not be limited by these terms. These terms are used to distinguish one element from another, or for the convenience of its description and explanation. For example, when “first element” is discussed in the description, it may be named “second element” or “third element,” and “second element” and “third element” may be named in a similar manner without departing from the teachings herein.

[0042] Given the measurements discussed and the errors associated with the measurement of a particular quantity (i.e., the limitations of the measurement system), as used herein, “about” or “approximately” includes stated values ​​and means within an acceptable range of deviation from a particular value as determined by one of ordinary skill in the art. For example, “about” may mean within one or more standard deviations, or within ±30%, ±20%, ±10%, ±5% of the stated value.

[0043] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It will also be understood that, unless expressly defined in the specification, terms such as those defined in a general dictionary should be interpreted as having a meaning consistent with their meaning in the context of the relevant field, and not as having an idealized or overly formal meaning.

[0044] Figure 1 This is a schematic diagram of a laser annealing apparatus according to an embodiment. Figure 1 As shown, the laser annealing apparatus according to the embodiment may include a laser beam source 10, a polygon mirror 30, a first Kerr cell 21, and a first optical element 41.

[0045] Laser beam source 10 can emit a linearly polarized laser beam. Laser beam source 10 may include a typical laser beam source and a linear polarizer. For example, a fiber laser can be used as laser beam source 10. Fiber lasers have characteristics such as wide-range output tuning, low maintenance costs, and high efficiency. Laser beam source 10 can be any other laser beam source that can be understood and appreciated by those skilled in the art.

[0046] The faceted mirror 30 reflects the incident laser beam output from the laser beam source 10, and the faceted mirror 30 can rotate about the rotation axis 30a. The laser beam emitted from the laser beam source 10 is reflected by the faceted mirror 30 and then reaches or is incident on the amorphous silicon (silicon) layer 2 located on the substrate 1, which can be placed on a stand (not shown). Therefore, the amorphous silicon layer 2 is annealed to a polycrystalline silicon layer.

[0047] By rotating the faceted mirror 30, the laser beam can illuminate the entire or most of the amorphous silicon layer 2. The laser beam reflected by the faceted mirror 30 can illuminate the amorphous silicon layer 2, and as the faceted mirror 30 rotates, the point on the amorphous silicon layer 2 where the laser beam reaches or is incident may change. Figure 1 As shown, when the laser beam emitted from the laser beam source 10 reaches or is incident on the first reflective surface 31 of the faceted mirror 30, as the faceted mirror 30 rotates about the rotation axis 30a in the direction indicated by the arrow, the point on the amorphous silicon layer 2 where the laser beam reaches or is incident moves approximately in the +Y direction. As the faceted mirror 30 rotates further or continues to rotate, the laser beam emitted from the laser beam source 10 reaches or is incident on the second reflective surface 32 of the faceted mirror 30. When the faceted mirror 30 rotates about the rotation axis 30a in the direction indicated by the arrow, the laser beam is again irradiated along a region of the upper surface of the amorphous silicon layer 2, in which the laser beam reflected by the first reflective surface 31 of the faceted mirror 30 has already been irradiated. Therefore, by rotating the faceted mirror 30 while moving the substrate 1 in the -X direction using a stage, the laser beam can ultimately irradiate the entire or most of the amorphous silicon layer 2.

[0048] Despite Figure 1 As shown, the laser beam reflected by the polygon mirror 30 can directly reach or be incident on the amorphous silicon layer 2, but the path of the laser beam reflected by the polygon mirror 30 can be adjusted using the first optical element 41 to ensure that the laser beam reaches or is incident on the amorphous silicon layer 2. Figure 1In this configuration, the first optical element 41 may include a first mirror 411 having a convex reflective surface and a second mirror 412 having a concave reflective surface. When the laser beam is reflected from a point on the first reflective surface 31, which is away from the second reflective surface 32, the laser beam can irradiate the vicinity of the edge of the amorphous silicon layer 2 in the -Y direction. When the laser beam is reflected from a point on the first reflective surface 31, which is adjacent to the second reflective surface 32, the laser beam can irradiate the vicinity of the edge of the amorphous silicon layer 2 in the +Y direction. Therefore, when the laser beam is reflected through the first reflective surface 31 while the polygon mirror 30 is rotating, the length of the region irradiated by the laser beam in the amorphous silicon layer 2 corresponds to, or is substantially the same as, the width of the amorphous silicon layer 2 in the Y direction.

[0049] The first Kerr cell 21 can be positioned or set on the path of the laser beam between the laser beam source 10 and the polygon mirror 30. Figure 2 It is located in Figure 1 A schematic diagram illustrating the change in the path of the laser beam within the first Kerr cell 21. The refractive index of the material inside the first Kerr cell 21 can be controlled by adjusting the strength of the electric field applied inside the first Kerr cell 21. In other words, birefringence may occur in the first Kerr cell 21 due to the electric field effect. The first Kerr cell 21 may include a material in which birefringence changes according to the strength of the electric field. For example, the first Kerr cell 21 may have a liquid such as a derivative of nitrobenzene and a pair of electrodes for applying an electric field to the liquid of the derivative. The liquid or the liquid of the derivative can be any material that can be understood and appreciated by those skilled in the art, and is not limited to nitrobenzene. When using the first Kerr cell 21, the refractive index of the material inside the first Kerr cell 21 can be controlled by adjusting the strength of the electric field, and thus the path of the laser beam passing through the first Kerr cell 21 can be controlled.

[0050] exist Figure 2 In the first Kerr cell 21, when no electric field is applied inside, the path of the laser beam may change as it travels along the path indicated by the dashed line, and when an electric field is applied, the laser beam travels along the path indicated by the solid line. The degree of change in the laser beam's path can vary depending on the strength of the applied electric field.

[0051] In order to control the path of the laser beam using the first Kerr cell 21, the linear polarization direction of the laser beam and the direction of the electric field need to be appropriately set. For example... Figure 2As shown, the linear polarization direction P1 of the laser beam emitted from the laser beam source 10 can lie in a plane (XY plane) that is parallel or substantially parallel to the direction (X direction) of the electric field generated in the first Kerr cell 21 and includes the linear path of the laser beam incident on the first Kerr cell 21, and can also be perpendicular to the linear path of the laser beam incident on the first Kerr cell 21. Furthermore, the linear polarization direction P2 of the laser beam that has passed through the first Kerr cell 21 can lie in a plane that is parallel or substantially parallel to the direction (X direction) of the electric field generated in the first Kerr cell 21 and includes the linear path of the laser beam that has passed through the first Kerr cell 21, and can also be perpendicular to the linear path of the laser beam that has passed through the first Kerr cell 21.

[0052] Figure 3 It can be used as Figure 1 A schematic perspective view of the faceted mirror 30, a constituent element of the laser annealing apparatus. In 3, the faceted mirror 30 may have a first reflecting surface 31 to a sixth reflecting surface 36. However, this disclosure is not limited to this, and the faceted mirror 30 may have any number of reflecting surfaces. When the faceted mirror 30 has an ideally previously set or configured shape, laser beam path adjustment using the first Kerr cell 21 may be unnecessary. However, in the process of manufacturing the laser annealing apparatus, the faceted mirror 30 may not have an ideally previously set or configured shape, and the faceted mirror 30 may deform during the process of using the laser annealing apparatus. For example, the path of the laser beam reflected by the faceted mirror 30 may not follow the previously set or configured path, and thus defects may be generated in the annealing of the amorphous silicon layer 2. In other words, defects in the constituent elements of the laser annealing apparatus may lead to defects in the annealing of the amorphous silicon layer 2.

[0053] However, the laser annealing apparatus according to the embodiment has a first Kerr cell 21 as described above. Therefore, by adjusting the path of the laser beam incident on the polygon mirror 30 using the first Kerr cell 21, the path of the laser beam reflected by the polygon mirror 30 follows a previously set or configured path, thereby effectively preventing the generation of defects or reducing the degree of defect generation. In other words, the Kerr cell can compensate for defects in the constituent elements of the laser annealing apparatus.

[0054] Figure 4 This is a schematic diagram of the trajectory of a laser beam illuminating the amorphous silicon layer 2 when the shape of the faceted mirror 30, positioned or placed in the optical path of the laser beam, is incorrect. Figure 4In the diagram, "1" represents the area irradiated by the laser beam reflected by the first reflecting surface 31 of the polygon mirror 30, "2" represents the area irradiated by the laser beam reflected by the second reflecting surface 32 of the polygon mirror 30, "3" represents the area irradiated by the laser beam reflected by the third reflecting surface 33 of the polygon mirror 30, "4" represents the area irradiated by the laser beam reflected by the fourth reflecting surface 34 of the polygon mirror 30, "5" represents the area irradiated by the laser beam reflected by the fifth reflecting surface 35 of the polygon mirror 30, and "6" represents the area irradiated by the laser beam reflected by the sixth reflecting surface 36 of the polygon mirror 30.

[0055] To anneal the amorphous silicon layer 2 without defects, the laser beam needs to be uniformly irradiated over the entire or most of the amorphous silicon layer 2. However, when the surface of the faceted mirror 30 does not have an ideal shape or configuration and the first Kerr cell 21 is not used, such as Figure 4 As shown, the size of the overlap between region 1, irradiated by the laser beam reflected from the first reflective surface 31 of the polygon mirror 30, and region 2, irradiated by the laser beam reflected from the second reflective surface 32 of the polygon mirror 30, may differ from the size of the overlap between region 3, irradiated by the laser beam reflected from the third reflective surface 33 of the polygon mirror 30, and region 4, irradiated by the laser beam reflected from the fourth reflective surface 34 of the polygon mirror 30. Furthermore, since region 2, irradiated by the laser beam reflected from the second reflective surface 32 of the polygon mirror 30, and region 3, irradiated by the laser beam reflected from the third reflective surface 33 of the polygon mirror 30, do not overlap, the laser beam may not irradiate a portion of the amorphous silicon layer 2. When this occurs, the polygon mirror 30 needs to be replaced, thus potentially substantially increasing manufacturing costs and / or potentially substantially increasing maintenance / repair costs of the laser annealing equipment.

[0056] However, for the laser annealing apparatus according to the embodiment, by controlling the path of the laser beam passing through the first Kerr cell 21, annealing defects on the amorphous silicon layer can be effectively prevented or reduced. For example, for Figure 1 and Figure 2 The laser annealing apparatus shown can control the degree of bending of the laser beam that has passed through the first Kerr cell 21 in the X direction by adjusting the intensity of the electric field in the X direction. Thus, it can control the positioning of the incident position of the laser beam in the X direction when it is incident on the amorphous silicon layer 2.

[0057] like Figure 4As shown, when the overlap between region 1 irradiated by the laser beam reflected from the first reflective surface 31 of the polygon mirror 30 and region 2 irradiated by the laser beam reflected from the second reflective surface 32 of the polygon mirror 30 is too large, the position of region 2 irradiated by the laser beam reflected from the second reflective surface 32 of the polygon mirror 30 can be adjusted by using the first Kerr cell 21 to adjust the optical path of the laser beam emitted from the laser beam source 10 and incident on the second reflective surface 32 of the polygon mirror 30. For example, the first potential difference applied to the first Kerr cell 21 when the laser beam emitted from the laser beam source 10 is incident on the first reflective surface 31 can be different from the second potential difference applied to the first Kerr cell 21 when the laser beam emitted from the laser beam source 10 is incident on the second reflective surface 32. By adjusting the position of the region irradiated by the laser beam, the position of region 2 irradiated by the laser beam can be adjusted by using the first Kerr cell 21. Figure 1 Laser annealing equipment such as Figure 5 The ground correction error is shown. This is illustrated as a schematic diagram of the trajectory of a laser beam irradiating the amorphous silicon layer 2. Figure 5 As shown, the laser beam can uniformly irradiate the amorphous silicon layer 2.

[0058] For reference, Figure 4 and Figure 5 In this case, because when the laser beam irradiates, while the multifaceted mirror 30 is rotated, the substrate 1 is moved at a substantially constant speed in the -X direction by using a stage, so the area irradiated by the laser beam is not parallel to the Y-axis, but tilted.

[0059] When the shape of the faceted mirror 30, which is an optical element positioned or arranged in the optical path of the laser beam, is incorrect, the area 1 irradiated by the laser beam reflected by the first reflecting surface 31 of the faceted mirror 30 and the area 2 irradiated by the laser beam reflected by the second reflecting surface 32 of the faceted mirror 30 may not be parallel to each other. This is, for example, in... Figure 6 As shown, Figure 6 This is a schematic diagram of the trajectory of a laser beam irradiating the amorphous silicon layer 2. When the laser beam is incident on the second reflective surface 32 of the polygon mirror 30, the potential difference applied to the first Kerr cell 21 may not remain constant at a specific value, but may vary appropriately. Therefore, the shape of the region 2 irradiated by the laser beam reflected by the second reflective surface 32 of the polygon mirror 30 may be deformed, or may become parallel to the region 1 irradiated by the laser beam reflected by the first reflective surface 31 of the polygon mirror 30.

[0060] The potential difference applied to the first Kerr cell 21 simultaneously with the laser beam incident on each reflective surface of the polygon mirror 30 can be changed or varied depending on each reflective surface of the polygon mirror 30. For example, as Figure 6As shown, given that the shapes of regions 1 to 6 formed by the laser beams reflected by the reflective surfaces 31 to 36 of the polygonal mirror 30 irradiating the amorphous silicon layer 2 are all different, the intensity of the electric field applied to the first Kerr cell 21 may change over time as follows: Figure 7 The changes shown are as follows.

[0061] exist Figure 7 In the diagram, "1" represents the change in the intensity of the electric field applied to the first Kerr cell 21 while the laser beam is reflected by the first reflecting surface 31 of the polygon mirror 30, "2" represents the change in the intensity of the electric field applied to the first Kerr cell 21 while the laser beam is reflected by the second reflecting surface 32 of the polygon mirror 30, "3" represents the change in the intensity of the electric field applied to the first Kerr cell 21 while the laser beam is reflected by the third reflecting surface 33 of the polygon mirror 30, "4" represents the change in the intensity of the electric field applied to the first Kerr cell 21 while the laser beam is reflected by the fourth reflecting surface 34 of the polygon mirror 30, "5" represents the change in the intensity of the electric field applied to the first Kerr cell 21 while the laser beam is reflected by the fifth reflecting surface 35 of the polygon mirror 30, and "6" represents the change in the intensity of the electric field applied to the first Kerr cell 21 while the laser beam is reflected by the sixth reflecting surface 36 of the polygon mirror 30.

[0062] Since the position of the area irradiated by the laser beam can be adjusted using the methods described above and the laser annealing equipment, errors can be corrected so that the laser beam can irradiate the area uniformly. Figure 5 On the amorphous silicon layer 2 shown.

[0063] Figure 8 This is a schematic perspective view of a portion of a laser annealing apparatus according to an embodiment. The laser annealing apparatus according to this embodiment differs from the laser annealing apparatus according to the above embodiment in that it includes a second Kerr cell 22 and a half-wave (λ / 2) plate (or λ / 2 delay plate) 23. Here, a half-wave (λ / 2) plate is used in this embodiment, but it is not limited thereto. In other embodiments, similar types of phase retardation plates or phase delay plates may be used.

[0064] The second Kerr cell 22 can be positioned or disposed on the path of the laser beam between the first Kerr cell 21 and the polygon mirror 30. The second Kerr cell 22 has the same or similar structure as the first Kerr cell 21. For example, the direction of the electric field generated in the second Kerr cell 22 can be perpendicular to the direction of the electric field generated in the first Kerr cell 21. The directions of the electric field applied to the first Kerr cell 21 and the electric field applied to the second Kerr cell 22 can both be perpendicular to the approximate direction of travel (Y direction) of the laser beam. The half-wave (λ / 2) plate 23 can be positioned or disposed on the path of the laser beam between the second Kerr cell 22 and the first Kerr cell 21.

[0065] As described above, the path of the laser beam can be controlled using the first Kerr cell 21. The direction in which the laser beam path is controlled can be approximately the direction in which the electric field is applied, i.e., Figure 2 The X direction is not directly related to the Z direction. Therefore, when it is necessary to control the path of the laser beam approximately in the Z direction, it may not be easy to effectively control the path of the laser beam using only the first Kerr cell 21. In the laser annealing apparatus according to the embodiment, in addition to the first Kerr cell 21, a second Kerr cell 22 may also be provided. For example, the direction of the electric field generated in the second Kerr cell 22 may be perpendicular to the direction of the electric field generated in the first Kerr cell 21. Therefore, by using the first Kerr cell 21 and the second Kerr cell 22, the path of the laser beam can be effectively controlled not only approximately in the X direction but also approximately in the Z direction.

[0066] As described above, it is important to properly set the linear polarization direction of the laser beam and the direction of the electric field in each of the first Kerr cell 21 and the second Kerr cell 22. In order to control the path of the laser beam using the first Kerr cell 21, the linear polarization direction P1 of the laser beam emitted from the laser beam source 10 may need to be in a plane (XY plane) parallel to the direction (X direction) of the electric field generated in the first Kerr cell 21 and including the linear path of the laser beam LB1 incident on the first Kerr cell 21, and may also need to be perpendicular to the linear path of the laser beam LB1 incident on the first Kerr cell 21. The linear polarization direction P2 of the laser beam that has passed through the first Kerr cell 21 may also be in a plane parallel to the direction (X direction) of the electric field generated in the first Kerr cell 21 and including the linear path of the laser beam LB2 that has passed through the first Kerr cell 21, and may also be perpendicular to the linear path of the laser beam LB2 that has passed through the first Kerr cell 21.

[0067] In order to control the path of the laser beam by using the second Kerr cell 22, such as Figure 8As shown, the linear polarization direction P3 of the laser beam LB3 incident on the second Kerr cell 22 may need to be in a plane (approximately the YZ plane) parallel to the direction (Z direction) of the electric field generated in the second Kerr cell 22 and including the linear path of the laser beam LB3 incident on the second Kerr cell 22, and may also need to be perpendicular to the linear path of the laser beam LB3 incident on the second Kerr cell 22. For this purpose, the laser beam LB2, having passed through the first Kerr cell 21, can pass through the half-wave (λ / 2) plate 23 before being incident on the second Kerr cell 22. The phase delay axis (also called the slow axis) of the half-wave (λ / 2) plate 23 can form an angle of approximately 45° with the linear polarization direction P2 of the laser beam LB2 that has passed through the first Kerr cell 21. Therefore, as the laser beam LB2, having passed through the first Kerr cell 21, passes through the half-wave (λ / 2) plate 23, the linear polarization direction P2 of the laser beam LB2 can rotate approximately 90°, thus... Figure 8 As shown, the laser beam LB3 incident on the second Kerr cell 22 can have a linear polarization direction P3.

[0068] The linear polarization P4 direction of the laser beam LB4 that has passed through the second Kerr cell 22 can also be in a plane (approximately the YZ plane) that is parallel to the direction (Z direction) of the electric field generated in the second Kerr cell 22 and includes the linear path of the laser beam LB4 that has passed through the second Kerr cell 22, and can be perpendicular to the linear path of the laser beam LB4 that has passed through the second Kerr cell 22.

[0069] Figure 9 This is a schematic diagram of a portion of a laser annealing apparatus according to an embodiment. Figure 9 The elements shown are for illustrative purposes. Figure 9 The laser annealing apparatus in this embodiment includes a second optical element 42. The second optical element 42 can be positioned or disposed on the laser beam path between the second Kerr cell 22 and the polygon mirror 30. The second optical element 42 ensures that the incident point of the laser beam LB1, emitted from the laser beam source 10 and passing through the second Kerr cell 22, on the polygon mirror 30 is the same as or substantially the same as the incident point of the laser beam emitted from the laser beam source 10 on the polygon mirror 30 in the absence of the second Kerr cell 22 and the first Kerr cell 21. By employing the second optical element 42, the optical path of the laser beam LB1 can be controlled without passing through the first Kerr cell 21 and / or the second Kerr cell 22.

[0070] As referenced above Figure 8 The second Kerr cell 22 can control the optical path of the laser beam in the Z direction, thus the laser beam (LB4', see...) after passing through the second Kerr cell 22... Figure 9The path of the laser beam LB0 can be different from the path of the laser beam LB1 emitted from the laser beam source 10 and passing through the second Kerr box 22, or when the optical path of the laser beam is not controlled. Therefore, the incident point of the laser beam LB1 on the polygon mirror 30, which is emitted from the laser beam source 10 and passes through the second Kerr box 22, can be different from the incident point of the laser beam on the polygon mirror 30 when the second Kerr box 22 and the first Kerr box 21 are absent, or when the optical path of the laser beam is not controlled. When the second Kerr box 22 changes the path of the laser beam approximately in the Z direction, such as... Figure 1 As shown, as the laser beam irradiates the amorphous silicon layer 2, the length of the region irradiated by the laser beam in the Y direction may decrease, and thus there may be regions in the amorphous silicon layer 2 that are not irradiated by the laser beam.

[0071] However, the laser annealing apparatus according to the embodiment may include a second optical element 42. The second optical element 42 causes the incident point of the laser beam LB1 emitted from the laser beam source 10 and passing through the second Kerr cell 22 on the polygon mirror 30 to be the same as or substantially the same as the incident point of the laser beam emitted from the laser beam source 10 on the polygon mirror 30 in the absence of the second Kerr cell 22 and the first Kerr cell 21, or without changing the optical path of the laser beam. In other words, the second optical element 42 changes the path of the laser beam that has passed through the second Kerr cell 22 from the path of laser beam LB4' to the path of laser beam LB4. Therefore, the problem of a reduction in the length of the region of the amorphous silicon layer 2 irradiated by the laser beam in the Y direction can be prevented or reduced.

[0072] For example, such as Figure 9 As shown, the second optical element 42 may include a first lens 421 protruding in the direction toward the polygon mirror 30 and a second lens 422 protruding in the direction toward the second Kerr cell 22. The focal length f of the first lens 421 and the focal length f of the second lens 422 may be the same or substantially the same as each other. The distance between the second Kerr cell 22 and the second lens 422 corresponds to the focal length f. The distance between the first lens 421 and the second lens 422 may be twice the focal length f. The distance between the first lens 421 and the point on the polygon mirror 30 where the laser beam arrives or is incident may be approximately the focal length f. The direction of the electric field generated in the second Kerr cell 22 (approximately, the Z direction) is perpendicular to the rotation axis 30a of the polygon mirror 30.

[0073] For reference, although Figure 9 The laser annealing apparatus shown includes a second Kerr cell 22 and a first Kerr cell 21; however, in embodiments, the number of Kerr cells may not be significant. In embodiments, what is important is that the laser annealing apparatus includes a Kerr cell that controls the path of the laser beam in approximately the Z-direction. Figure 9In this text, the second Kerr box 22 is described as an embodiment performing this function. However, referring to the Kerr box as the first and / or second is arbitrary, and for ease of explanation, the Kerr box may be referred to as the first Kerr box.

[0074] In the above embodiments, an actuator capable of adjusting the position of the first Kerr cell 21, the second Kerr cell 22, and / or the half-wave (λ / 2) plate 23 in three-dimensional space can be provided.

[0075] For example, in Figure 8 In order to rotate the linear polarization direction P2 of the laser beam LB2, which has passed through the first Kerr cell 21, by approximately 90° through the half-wave plate 23, the laser beam LB2, having passed through the first Kerr cell 21, is incident perpendicularly onto the half-wave plate 23, and the linear polarization direction P2 of the laser beam LB2 forms an angle of approximately 45° with the phase delay axis (slow axis) of the half-wave plate 23. The first Kerr cell 21 changes the path of the laser beam in the X direction. Therefore, by using an actuator to rotate the half-wave plate 23 around the Z-axis by a specific angle, the laser beam LB2, having passed through the first Kerr cell 21, can be incident perpendicularly or approximately perpendicularly onto the half-wave plate 23, and the linear polarization direction P2 of the laser beam LB2 can form an angle of approximately or approximately 45° with the phase delay axis (slow axis) of the half-wave plate 23.

[0076] Although the laser annealing apparatus has been described as above, this disclosure is not limited thereto. For example, laser annealing methods using the laser annealing apparatus are included within the scope of this disclosure, as are methods for manufacturing substrates having polycrystalline silicon layers using the laser annealing apparatus or methods for manufacturing display devices using the laser annealing apparatus.

[0077] For example, a method for manufacturing a substrate having a polycrystalline silicon layer according to embodiments of this disclosure may include, as follows: Figure 1 As shown and as Figure 10 The flowchart illustrates the formation of an amorphous silicon layer 2 on a substrate 1 and the irradiation of the amorphous silicon layer 2 with a laser beam. The laser beam, linearly polarized and passing through a first Kerr cell 21, is reflected by a polygon mirror 30 rotating about a rotation axis 30a and passes through a first optical element 41 to irradiate the amorphous silicon layer 2. Therefore, the use of the first Kerr cell 21 can effectively prevent or reduce laser beam path errors that may occur in the polygon mirror 30.

[0078] The faceted mirror 30 has a first reflective surface 31 and a second reflective surface 32. During laser beam irradiation, when the first potential difference applied to the first Kerr cell 21 simultaneously with the laser beam incident on the first reflective surface 31 differs from the second potential difference applied to the first Kerr cell 21 simultaneously with the laser beam incident on the second reflective surface 32, the laser beam can irradiate the amorphous silicon layer 2. (Refer to the above.) Figure 4 and Figure 5The above operations have been described.

[0079] Alternatively, during laser beam irradiation, the laser beam can be directed onto the amorphous silicon layer 2 by changing the second potential difference applied to the first Kerr cell 21 while the polygon mirror 30 rotates and the laser beam is incident on the second reflective surface 32. (Refer to above) Figure 6 The above operations have been described.

[0080] When illuminated by a laser beam, the laser beam is a linearly polarized laser beam, and as follows: Figure 2 The linear polarization P1 direction shown can be parallel to the direction of the electric field generated in the first Kerr cell 21 (generally, the X direction) and can be perpendicular to the linear path of the laser beam incident on the first Kerr cell 21, which is positioned or disposed in a plane (generally, the XY plane) that includes the linear path of the laser beam incident on the first Kerr cell 21.

[0081] Under the irradiation of a laser beam, such as Figure 8 As shown, the laser beam LB1 passes through the first Kerr cell 21, then through the half-wave plate 23 and the second Kerr cell 22, and is incident on the polygon mirror 30 to irradiate the amorphous silicon layer 2. The direction of the electric field generated in the second Kerr cell 22 (approximately the Z direction) can be perpendicular to the direction of the electric field generated in the first Kerr cell 21 (approximately the X direction).

[0082] Under the irradiation of a laser beam, such as Figure 9 As shown, the laser beam LB1 can pass through the second optical element 42, can be incident on the polygon mirror 30, and can irradiate the amorphous silicon layer 2. The second optical element 42 ensures that the incident point of the laser beam on the polygon mirror 30 after passing through the second Kerr cell 22 is the same as or substantially the same as the incident point of the laser beam on the polygon mirror 30 when the second Kerr cell 22 is absent or the optical path of the laser beam is not controlled. (See above for reference.) Figure 9 The above operations have been described. For example, the direction of the electric field generated in the second Kerr cell 22 (approximately the Z direction) can be perpendicular to the rotation axis 30a of the polygon mirror 30.

[0083] The aforementioned laser annealing equipment can be used to reduce the degree of defects generated in polycrystalline silicon layers due to defects in optical elements or constituent components.

[0084] For example, in the first mirror 411 with a convex reflective surface (refer to...) Figure 1Defects may occur in a portion of the surface of the amorphous silicon layer 2. In this case, if the first Kerr cell 21 is absent, or otherwise the optical path of the laser beam is not controlled, the polycrystalline silicon layer obtained by annealing the amorphous silicon layer 2 may have regions affected by the defects of the first mirror 411. When the amorphous silicon layer 2 is annealed while the substrate 1 is moved in the -X direction on the stage, the affected region of the polycrystalline silicon layer may have a linear shape extending approximately in the X direction. When a display device is manufactured using a substrate with a polycrystalline silicon layer, pixels in the region with the linear shape may have characteristics different from other pixels, which may be easily identifiable by the user.

[0085] In laser annealing, when the path of the laser beam is alternately changed in the +X and -X directions using the first Kerr cell 21, even if the first mirror 411 has defects, the region on the polysilicon layer affected by the defects may not have a linear shape extending approximately in the X direction, but may have, for example, a zigzag shape. When a display device is manufactured using a substrate with such a polysilicon layer, the user may not easily identify this zigzag shape. Therefore, the above method can effectively prevent or reduce the generation or causes of defects that may be identifiable by the user.

[0086] According to the above embodiments, a laser annealing apparatus can be realized that can obtain previously expected results even when the shape of a constituent element is incorrect, and a method for manufacturing a substrate with a polycrystalline silicon layer using the laser annealing apparatus can be achieved. However, the scope of this disclosure is not limited thereto.

[0087] It should be understood that the embodiments described herein should be considered in a descriptive sense only and not for limiting purposes. The description of features or aspects within each embodiment should generally be taken into account for other similar features or aspects in other embodiments. Although one or more embodiments have been described with reference to the accompanying drawings, those skilled in the art will understand that various changes in form and detail may be made therein without departing from the spirit and scope defined by this disclosure.

Claims

1. A laser annealing apparatus, wherein, The laser annealing equipment includes: A laser beam source that emits a linearly polarized laser beam; A multifaceted mirror that rotates about a rotation axis and reflects the linearly polarized laser beam emitted from the laser beam source; A first Kerr cell, disposed on the laser beam path between the laser beam source and the polygonal mirror; and A first optical element guides the linearly polarized laser beam reflected by the polygonal mirror toward the amorphous silicon layer, wherein the linearly polarized laser beam irradiates the amorphous silicon layer. The multifaceted mirror includes a first reflective surface and a second reflective surface. A first potential difference is applied to the first Kerr cell simultaneously with the linearly polarized laser beam emitted from the laser beam source incident on the first reflective surface, and A second potential difference is applied to the first Kerr cell simultaneously with the linearly polarized laser beam emitted from the laser beam source incident on the second reflective surface. The first potential difference is different from the second potential difference.

2. The laser annealing equipment according to claim 1, wherein, The linear polarization direction of the linearly polarized laser beam emitted from the laser beam source lies in a plane parallel to the direction of the electric field generated in the first Kerr cell and including the linear path of the linearly polarized laser beam incident on the first Kerr cell. The linear polarization direction is perpendicular to the linear path of the linearly polarized laser beam incident on the first Kerr cell.

3. The laser annealing equipment according to claim 1, wherein, The laser annealing equipment also includes: A second optical element is disposed in the laser beam path between the first Kerr cell and the polygonal mirror. The second optical element causes the incident point of the linearly polarized laser beam on the polygon mirror after passing through the first Kerr cell to be the same as the incident point of the linearly polarized laser beam emitted from the laser beam source on the polygon mirror when the first Kerr cell is not placed between the laser beam source and the polygon mirror.

4. The laser annealing equipment according to claim 3, wherein, The direction of the electric field generated in the first Kerr cell is perpendicular to the rotation axis of the polygonal mirror.

5. The laser annealing equipment according to claim 1, wherein, The laser annealing equipment also includes: A second Kerr cell is disposed on the laser beam path between the first Kerr cell and the polygonal mirror; and A half-wave plate is disposed on the laser beam path between the second Kerr cell and the first Kerr cell. The direction of the electric field generated in the second Kerr cell is perpendicular to the direction of the electric field generated in the first Kerr cell.

6. The laser annealing equipment according to claim 1, wherein, The first optical element includes: A first mirror, the first mirror having a convex reflective surface; and The second mirror has a concave reflective surface.

7. The laser annealing equipment according to claim 3, wherein, The laser annealing apparatus further includes: a second Kerr cell, the second Kerr cell being disposed on the laser beam path between the first Kerr cell and the polygonal mirror, wherein the second optical element includes: A first lens, the first lens protruding toward the polygonal mirror; and The second lens protrudes toward the second Kerr cell.

8. A laser annealing apparatus, wherein, The laser annealing equipment includes: A laser beam source that emits a linearly polarized laser beam; A multifaceted mirror that rotates about a rotation axis and reflects the linearly polarized laser beam emitted from the laser beam source; A first Kerr cell, disposed on the laser beam path between the laser beam source and the polygonal mirror; and A first optical element guides the linearly polarized laser beam reflected by the polygonal mirror toward the amorphous silicon layer, wherein the linearly polarized laser beam irradiates the amorphous silicon layer. The multifaceted mirror includes a first reflective surface and a second reflective surface, and During the rotation of the polygonal mirror and the incident of the linearly polarized laser beam emitted from the laser beam source onto the second reflective surface, the potential difference applied to the first Kerr cell is non-constant.

9. A method for manufacturing a substrate having a polycrystalline silicon layer, wherein, The method includes: An amorphous silicon layer is formed on the substrate; and After the linearly polarized laser beam passes through the first Kerr cell, is reflected by a multifaceted mirror rotating around the rotation axis, and is projected onto the first optical element, the linearly polarized laser beam is then directed onto the amorphous silicon layer, wherein... In the process of irradiating the amorphous silicon layer with the linearly polarized laser beam. A first potential difference is applied to the first Kerr cell simultaneously with the linearly polarized laser beam incident on the first reflective surface of the polygonal mirror, and A second potential difference is applied to the first Kerr cell simultaneously with the linearly polarized laser beam incident on the second reflective surface of the polygonal mirror. The first potential difference and the second potential difference are different from each other.

10. The method according to claim 9, wherein, The method further includes: rotating the polygonal mirror while moving the substrate in a predetermined direction.

11. The method according to claim 9, wherein, In the irradiation by the linearly polarized laser beam, the linearly polarized laser beam, having a linear polarization direction, is irradiated onto the amorphous silicon layer through the first Kerr cell, and The linear polarization direction is in a plane parallel to the direction of the electric field generated in the first Kerr cell and includes the linear path of the linearly polarized laser beam incident on the first Kerr cell, and the linear polarization direction is perpendicular to the linear path of the linearly polarized laser beam incident on the first Kerr cell.

12. The method according to claim 9, wherein, During the illumination by the linearly polarized laser beam, the linearly polarized laser beam illuminates the amorphous silicon layer through a second optical element passing between the first Kerr cell and the polygonal mirror. The second optical element causes the incident point of the linearly polarized laser beam on the polygon mirror after passing through the first Kerr cell to be the same as the incident point of the linearly polarized laser beam on the polygon mirror when the first Kerr cell is not placed between the laser beam source and the polygon mirror.

13. The method according to claim 12, wherein, During the illumination by the linearly polarized laser beam, the direction of the electric field generated in the first Kerr cell is perpendicular to the rotation axis of the polygonal mirror.

14. The method according to claim 9, wherein, During the irradiation by the linearly polarized laser beam, the beam passes sequentially through the first Kerr cell, the half-wave plate, and the second Kerr cell to be incident on the polygonal mirror. The linearly polarized laser beam then irradiates the amorphous silicon layer. The direction of the electric field generated in the second Kerr cell is perpendicular to the direction of the electric field generated in the first Kerr cell.

15. A method for manufacturing a substrate having a polycrystalline silicon layer, wherein, The method includes: An amorphous silicon layer is formed on the substrate; and After the linearly polarized laser beam passes through the first Kerr cell, is reflected by a multifaceted mirror rotating around the rotation axis, and is projected onto the first optical element, the linearly polarized laser beam is then directed onto the amorphous silicon layer, wherein... The faceted mirror includes a first reflective surface and a second reflective surface, and during the process of irradiating the amorphous silicon layer with the linearly polarized laser beam, while the faceted mirror is rotated and the linearly polarized laser beam is incident on the second reflective surface of the faceted mirror, the potential difference applied to the first Kerr cell is non-constant.

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