Optical heating device

Abstract

To provide an optical heating device capable of more efficiently enhancing illuminance of heating light with respect to a peripheral end part of an object to be heated.　Provided is an optical heating device for irradiating an object to be heated with light to heat the object to be heated, characterized in that: the optical heating device comprises a light source unit having a support unit for supporting the object to be heated, a plurality of first LEDs positioned outside a central part of the object to be heated when viewed in a direction normal to a main surface of the object to be heated supported by the support unit, and a plurality of second LEDs positioned in a region facing the center part of the object to be heated, and also comprises a first optical system arranged between the object to be heated and the light source unit in the direction normal to the main surface of the object to be heated; and the first optical system refracts at least some of first heating light emitted by the first LEDs so that the refracted light advances to a peripheral end part of the object to be heated.

Description

light heating device

[0001] The present invention relates to an optical heating device that heats a processing object by irradiating the processing object with light for heating (hereinafter referred to as "heating light" for convenience).

[0002] In semiconductor manufacturing processes, various processes such as film formation, oxidation / diffusion, modification, and annealing are performed on objects such as semiconductor wafers. These processes often employ a heating method in which heating light is applied to the main surface of the object because it allows for non-contact processing. Here, the "main surface" refers to the surface that is much larger in area than the other surfaces of a plate-like object.

[0003] Examples of light sources for the heating light include halogen lamps and LEDs. Of these, LEDs are increasingly being adopted because they allow for rapid temperature rise of the object to be heated (hereinafter referred to as the "object to be heated" for convenience).

[0004] The light output of a single LED is typically smaller than that of, for example, a halogen lamp. Therefore, in order to irradiate the heating object with the heating light required for processing, multiple LEDs are arranged in a densely packed state, as shown in Patent Document 1 below.

[0005] Special table 2018-525813 publication

[0006] The use of LEDs as a light source for heating light enables rapid temperature rise of the object to be heated. However, in recent years, there has been an increasing demand for heat treatment of the object to be heated at a higher temperature while achieving rapid temperature rise.

[0007] Here, the peripheral edges of the main surface of the heating object dissipate heat more easily than the central portion. Therefore, when heating the heating object, it is necessary to irradiate the peripheral edges with heating light at a higher illuminance than the central portion in order to compensate for the heat dissipation at the peripheral edges. Furthermore, assuming that the heating object is to be heated at a higher temperature, the illuminance of the heating light required at the peripheral edges of the heating object will be higher than in the past.

[0008] In order to irradiate a large amount of heating light onto the peripheral edge of the object to be heated and increase the illuminance at the peripheral edge, it is conceivable to add LEDs facing the peripheral edge. However, in conventional light heating devices, the LEDs facing the peripheral edge are arranged as close as possible to each other (see Patent Document 1). In other words, the LEDs are arranged densely in the area facing the peripheral edge, making it difficult to add LEDs facing the peripheral edge.

[0009] Furthermore, LEDs have the property that their light-emitting efficiency decreases as the temperature of the LEDs themselves increases. Therefore, for closely spaced LEDs, increasing the heating temperature of the peripheral edge by further reducing the spacing between adjacent LEDs or by adding additional LEDs actually reduces the intensity of the light emitted from each LED. Therefore, the above-mentioned measures cannot efficiently increase the illuminance of the heating light on the peripheral edge, and are therefore not substantially effective.

[0010] In view of the above circumstances, an object of the present invention is to provide a light heating device that can more efficiently increase the illuminance of heating light on the peripheral edge of an object to be heated.

[0011] The optical heating device of the present invention is an optical heating device that irradiates a heating object with light to perform a heating process on the heating object, and comprises: a support unit that supports the heating object; a light source unit having a plurality of first LEDs that are located outside the center of the heating object when viewed in the normal direction of the main surface of the heating object supported by the support unit, and a plurality of second LEDs that are located in an area opposite the center of the heating object; and a first optical system that is arranged between the heating object and the light source unit in the normal direction of the main surface of the heating object, and is characterized in that the first optical system refracts at least a portion of the first heating light emitted by the first LEDs and causes it to proceed toward the peripheral edge of the heating object.

[0012] Here, the peripheral edge of the object to be heated refers to a region on the main surface of the object to be heated that is 30% or less of the diameter of the main surface from the edge, and the central part of the object to be heated refers to a region inside the peripheral edge within the main surface of the object to be heated.

[0013] According to the above configuration, the first heating light emitted by the first LED is efficiently irradiated onto the peripheral edge of the object to be heated. More specifically, because the heating light emitted by the LED has low directionality, the heating light is emitted with a predetermined spread from the light-emitting surface of the LED. Therefore, assuming that the first optical system is not provided, the first heating light includes heating light irradiated toward the center of the object to be heated and heating light traveling in a direction different from the object to be heated. In contrast, according to the above configuration, at least a portion of this heating light is irradiated onto the peripheral edge of the object to be heated. As a result, the amount of heating light irradiated onto the peripheral edge increases, and the illuminance of the heating light on the peripheral edge is increased.

[0014] Furthermore, the above configuration is preferable because it increases the arrangement density of the first LEDs, suppresses a decrease in the light-emitting efficiency of the first LEDs, and increases the illuminance on the peripheral edge of the object to be heated.

[0015] For example, the optical member that refracts the first heating light may be a convex lens, a prism, a Fresnel lens, or the like.

[0016] In the above-mentioned optical heating device, the plurality of first LEDs may include LEDs that are positioned outside the peripheral edge of the object to be heated when viewed in the normal direction, and the first optical system may refract the heating light emitted by the LEDs that are positioned outside the peripheral edge of the object to be heated when viewed in the normal direction, and direct the heating light toward the peripheral edge of the object to be heated.

[0017] When viewed in the normal direction, the region located outside the peripheral edge of the object to be heated is different from the conventional region where LEDs facing the peripheral edge are densely arranged. In other words, with the above configuration, the LED arrangement density is increased, and a decrease in the light emission efficiency of the LEDs is suppressed, while more LEDs can be arranged in the light source unit.

[0018] Furthermore, it is assumed that the heating light emitted by the first LED positioned outside the peripheral edge of the heated object when viewed in the normal direction has many components traveling in a direction different from that of the heated object. In contrast, with the first optical system, the heating light emitted by the first LED is guided to the peripheral edge of the heated object, thereby increasing the amount of heating light irradiated to the peripheral edge.

[0019] In the above-mentioned optical heating device, the first optical system is a converging optical system that is individually arranged for an LED that is located outside the peripheral edge of the object to be heated when viewed in the normal direction, and reduces the divergence angle of the incident heating light, and when viewed in the normal direction, the focus of the first optical system may be located closer to the object to be heated than the center of the light-emitting surface of the LED on which the first optical system is arranged.

[0020] From the viewpoint of irradiating as much of the first heating light as possible onto the peripheral edge of the object to be heated, it is preferable that the first optical system be a converging optical system that reduces the divergence angle of the first heating light. Furthermore, by arranging the focal point of the first optical system as described above, it is possible to guide most of the heating light emitted by the LED to the peripheral edge of the object to be heated.

[0021] Furthermore, in the above-mentioned optical heating device, the first optical system is a converging optical system arranged for a plurality of LEDs that are located outside the peripheral edge of the object to be heated when viewed in the normal direction, and when viewed in the normal direction, the focus of the first optical system may be located closer to the object to be heated than the center of the light-emitting surface of the plurality of LEDs on which the first optical system is arranged.

[0022] In the above-mentioned optical heating device, the plurality of first LEDs may include LEDs located in an area facing the peripheral edge of the object to be heated, and the first optical system may be a converging optical system that reduces the divergence angle of the heating light emitted by the LEDs located in the area facing the peripheral edge of the object to be heated.

[0023] According to the above configuration, the heating light emitted by the first LED facing the peripheral edge of the heating target is guided to the peripheral edge with a reduced divergence angle, thereby enabling the heating light to be efficiently irradiated onto the peripheral edge.

[0024] Furthermore, as described above, because the heating light emitted by the LED has low directionality, assuming that the first optical system is not provided, the heating light emitted by the first LED includes a component that is irradiated toward the center of the heating object. Here, in the heating process of the heating object, the temperature within the main surface of the heating object is typically made uniform in order to perform uniform processing within the main surface of the heating object. In this case, to compensate for heat dissipation at the peripheral edge, the illuminance of the heating light on the peripheral edge side is made different from the illuminance of the heating light on the central side, and the heating light is irradiated at a higher illuminance toward the peripheral edge side than toward the central side.

[0025] Here, assuming that the heating temperature of the heating object is increased while maintaining a uniform temperature across the main surface of the heating object, it is necessary to increase the difference in illuminance at the peripheral edge relative to the illuminance at the central edge. In contrast, with the above configuration, the first optical system changes the direction of the heating light toward the central edge and guides it toward the peripheral edge. This increases the difference in illuminance between the peripheral edge and the central edge. In other words, the above configuration is suitable for increasing the illuminance at the peripheral edge compared to the illuminance at the central edge. Furthermore, from the perspective of more efficiently increasing the illuminance at the peripheral edge, various optical systems that direct the heating light emitted by the first LED toward the peripheral edge may be used as the first optical system.

[0026] In the light heating device, the plurality of first LEDs may be arranged in an area facing a peripheral edge of the object to be heated.

[0027] According to the above configuration, the area required for arranging the first LED is reduced compared to the above-described configuration in which the first LED is arranged outside the heating object when viewed in the normal direction. In other words, the above configuration is preferable because it makes it easy to reduce the dimensions of the optical heating device.

[0028] The light heating device may include a second optical system that refracts the second heating light emitted by the second LED and causes the second heating light to travel toward the peripheral edge of the object to be heated.

[0029] According to the above configuration, a portion of the second heating light that would be irradiated toward the center of the object to be heated if the second optical system were not provided is irradiated toward the peripheral edge of the object to be heated, thereby increasing the illuminance at the peripheral edge.

[0030] Furthermore, with the above configuration, it is easy to increase the difference in illuminance between the peripheral edge and the central portion.

[0031] Furthermore, the second optical system may be a converging optical system, such as a convex lens, that reduces the divergence angle of the incident second heating light. By guiding the second heating light to the peripheral edge of the object to be heated with the divergence angle of the second heating light reduced, the illuminance at the peripheral edge can be further increased.

[0032] In the above-mentioned optical heating device, the light source unit includes an LED substrate having a mounting surface parallel to the main surface of the object to be heated, and the first LED and the second LED of the LED substrate may be mounted on the mounting surface.

[0033] According to the above configuration, the first LED and the second LED are arranged parallel to the main surface of the heating object. Therefore, when a cooling member such as a heat sink for cooling the first LED and the second LED is arranged on the LED substrate, the cooling member can be arranged parallel to the main surface, just like the first LED and the second LED. Therefore, the above configuration is preferable because it makes it easy to design the cooling member.

[0034] The optical heating device further includes a chamber that houses the support unit and the light source unit, and a partition plate that separates the space in the chamber where the object to be heated is located from the space where the light source unit is located, and the first optical system may be formed integrally with the partition plate.

[0035] According to the above configuration, even when a heating object is heat-treated with a process gas introduced into the chamber or with the chamber in a vacuum atmosphere, contact between the process gas or the vacuum atmosphere and the first LED and the second LED is suppressed. In other words, the above configuration is preferable because it can reduce deterioration of the LEDs due to the process gas, etc.

[0036] According to the present invention, there is provided a light heating device that can more efficiently increase the illuminance of heating light on the peripheral edge of the main surface of an object to be heated.

[0037] 8A is a side cross-sectional view showing an example of the configuration of a light heating device according to the present invention. FIG. 1 is a plan view when FIG. 1 is viewed in the Z direction. FIG. 2A is a plan view showing the positional relationship of LEDs with respect to the object to be heated in FIG. 2A. FIG. 1B is a view showing an enlarged portion of FIG. 1. FIG. 3 is a view showing the mode of propagation of heating light emitted by the LEDs in FIG. 3. FIG. 4 is a view schematically showing the simulation conditions for verification 1. FIG. 5 is a graph showing the results of verification 1. FIG. 6 is a view schematically showing the simulation conditions for verification 2. FIG. 7 is a graph showing the results of verification 2. FIG. 8A is a view schematically showing the simulation conditions for verification 3. FIG. 9 is a graph showing the results of verification 3. FIG. 10A is a side cross-sectional view of a light heating device according to a second embodiment. FIG. 8A is an enlarged view of a portion of FIG. 8A. FIG. 10A is a side cross-sectional view of a modified light heating device. FIG. 10B is a side cross-sectional view of a modified light heating device. FIG. 11 is a side cross-sectional view of a modified light heating device. FIG. 11 is a plan view when FIG. 11 is viewed in the Z direction. FIG. 12 is a plan view showing another example of the arrangement of LEDs. FIG. 13 is a side cross-sectional view of a modified light heating device. 17 is a side cross-sectional view of a modified example of the light heating device, and FIG. 18 is a side cross-sectional view of a modified example of the light heating device, and FIG. 19 is a plan view when FIG. 17 is viewed in the Z direction.

[0038] [First embodiment] Hereinafter, an embodiment of the light heating device according to the present invention will be described with reference to the drawings. Note that the drawings are all schematic illustrations, and the dimensional ratios and numbers in the drawings do not necessarily correspond to the actual dimensional ratios and numbers.

[0039] Fig. 1 is a side cross-sectional view showing an example of the configuration of an optical heating device according to the present invention. The optical heating device 1 performs a heat treatment on an object W1 to be heated by irradiating the object W1 with heating light. As shown in Fig. 1, the optical heating device 1 includes a chamber 8, a support unit 2, a light source unit 3, and a first optical system 10. The light source unit 3 includes first LEDs (5a, 5b), a second LED 6, and an LED substrate 7.

[0040] In the following description, an X-Y-Z coordinate system will be referred to as appropriate, in which the normal direction to the main surface W1a of the heating object W1 is the Z direction and the plane perpendicular to the Z direction is the XY plane. When expressing a direction, a positive or negative sign is added, such as "+X direction" and "-X direction." When expressing a direction without distinguishing between positive and negative, the direction is simply referred to as "X direction." In other words, in this specification, when simply referring to the "X direction," both the "+X direction" and the "-X direction" are included. The same applies to the Y direction and the Z direction.

[0041] As shown in FIG. 1 , the chamber 8 includes a support unit 2 therein that supports the heating object W1. The support unit 2 supports the heating object W1 so that the main surface W1a of the heating object W1 is parallel to the XY plane. As an example, the support unit 2 is configured to support the heating object W1 by negative pressure generated by an air intake mechanism (not shown). The support unit 2 may be configured in any way as long as it can support the heating object W1 with the main surface W1a parallel to the XY plane. For example, the support unit 2 may include a plurality of pin-shaped protrusions that support the heating object W1.

[0042] In this embodiment, the heating object W1 is a semiconductor wafer such as a silicon substrate. The diameter of the main surface W1a of the heating object W1 is arbitrary, but as an example, the diameter is set to 300 mm.

[0043] As shown in Fig. 1, the first LEDs (5a, 5b) and the second LED 6 are arranged on a -Z side principal surface 7a of the LED substrate 7, which is parallel to a +Z side principal surface W1a of the heating object W1. The principal surface 7a corresponds to the "mounting surface." Note that the second LED 6 is illustrated simply with a portion thereof omitted.

[0044] 1, by arranging the first LEDs (5a, 5b) on a surface (main surface 7a) parallel to the main surface W1a of the heating object W1, it becomes easy to design a cooling member (not shown) such as a heat sink for cooling the first LEDs (5a, 5b), even when the cooling member is arranged on the main surface on the +Z side of the LED substrate 7. Note that a similar discussion can be made for the second LEDs 6.

[0045] 2A is a plan view of FIG. 1 as viewed in the Z direction. For ease of illustration, FIG. 2A shows the heating object W1 and lenses (11a, 11b) described below in a transparent manner. FIG. 2B is a plan view showing the positional relationship of the LEDs relative to the heating object W1 in FIG. 2A. More specifically, FIG. 2B corresponds to a view in which the first optical system 10, LED substrate 7, chamber 8, and flat glass 9 are omitted from FIG. 2A. In each drawing, the first LEDs (5a, 5b) are hatched for ease of understanding.

[0046] In Figure 2B, the central portion C1 of the object to be heated W1 is hatched. As shown in Figure 2B, the first LEDs (5a, 5b) are located outside the central portion C1 of the object to be heated W1 when viewed in the Z direction. More specifically, the first LEDs (5a, 5b) include a first LED 5a arranged in an area located outside the peripheral edge E1 of the object to be heated W1 when viewed in the Z direction, and a first LED 5b arranged in an area facing the peripheral edge E1 of the object to be heated W1. Furthermore, the second LED 6 is located in a position overlapping the central portion C1 of the object to be heated W1 when viewed in the Z direction, and is arranged in an area facing the central portion C1.

[0047] Since the first LED 5a is arranged outside the object to be heated W1, even if additional first LEDs 5a are arranged, the arrangement density of the first LEDs 5b and the second LEDs 6 can be prevented from increasing.

[0048] 3 is an enlarged view of a portion of FIG. 1. The first optical system 10 is composed of lenses 11a arranged corresponding to each of the first LEDs 5a and lenses 11b arranged corresponding to each of the first LEDs 5b. As shown in FIG. 3, the first optical system 10 is formed on the -Z side of the flat glass 9. It is optional whether or not lenses (11a, 11b) are arranged for all of the first LEDs (5a, 5b). For example, lenses 11b may be arranged for some of the first LEDs 5b.

[0049] The flat glass 9 transmits the heating light emitted by the first LEDs (5 a, 5 b) and the second LED 6. Here, "transmitting" means that the light transmittance for the heating light is 80% or more. The flat glass 9 is made of a glass material such as synthetic quartz glass.

[0050] As shown in FIG. 3, the lenses (11a, 11b) have a light incident surface 12 formed by the main surface on the +Z side of the flat glass 9. The lenses (11a, 11b) also have a light exit surface 13 that is convex on the side of the object to be heated W1 (-Z side). The light exit surfaces 13 of the lenses (11a, 11b) are arranged on the optical axes A1 of the corresponding first LEDs (5a, 5b). Here, the optical axis of the LED refers to a normal line passing through the center of the light-emitting surface of the LED.

[0051] 3, the focal point F1a of the lens 11a is positioned closer to the object to be heated W1 than the optical axis A1 of the corresponding first LED 5a, and the focal point F1b of the lens 11b is positioned on the optical axis A1 of the corresponding first LED 5b.

[0052] 4 is a diagram showing the propagation of the heating light (L1a, L1b) emitted by the first LED (5a, 5b) and the heating light L2 emitted by the second LED 6 in FIG. 3. As shown in FIG. 4, the first LED (5a, 5b) and the second LED 6 each emit heating light toward the -Z side. As an example, these heating lights have peak wavelengths in the range of 350 nm to 450 nm. The heating light L1a and the heating light L1b correspond to the "first heating light," and the heating light L2 corresponds to the "second heating light."

[0053] As described above, the focal point F1a of the lens 11a is located closer to the object to be heated W1 than the optical axis A1 of the corresponding first LED 5a. Therefore, a portion of the heating light L1a incident on the lens 11a is guided toward the object to be heated W1, as shown in FIG. 4. In other words, the lens 11a guides the heating light L1 toward the object to be heated W1 while reducing the divergence angle of the heating light L1a. This allows a large amount of the heating light L1a to be irradiated onto the peripheral edge E1 of the main surface W1a of the object to be heated W1.

[0054] Furthermore, the focal point F1b of the lens 11b is located on the optical axis A1 of the corresponding first LED 5b. Therefore, as shown in Fig. 4, the heating light L1b incident on the lens 11b is guided to the peripheral edge E1 with a reduced divergence angle. As a result, a large amount of heating light L1b is irradiated onto the peripheral edge E1.

[0055] The focal lengths of the lenses (11a, 11b) and the distance between the lenses (11a, 11b) and the object to be heated W1 in the Z direction can be adjusted as appropriate.

[0056] In the first optical system 10, the radii of curvature of the light exit surfaces 13 of the lenses (11a, 11b) may be different from each other.

[0057] In this embodiment, the lenses (11a, 11b) have a convex shape on the −Z side. However, from the viewpoint of reducing aberration and more accurately irradiating the heating object W1 with the heating light (L1a, L1b), the lenses (11a, 11b) may have a convex shape on the +Z side.

[0058] In this embodiment, no optical system, such as a lens, is provided for the second LED 6. Therefore, the heating light L2 is emitted from the light-emitting surface of the second LED 6 and then irradiated onto a wide area, including the central portion C1 of the object to be heated W1 (see FIG. 4 ). From the viewpoint of preventing localized high illuminance in a portion of the central portion C1, it is preferable that no optical system is provided for all or at least a portion of the second LED 6, and that the heating light L2 is irradiated onto a wide area. Note that an optical system, such as a lens, may be provided for the second LED 6 depending on the desired illuminance distribution; this configuration will be described later.

[0059] [Verification 1] We verified through simulation that the illuminance of the heating light irradiated to the peripheral edge E1 of the heating object W1 is increased by the lens 11a whose focus F1a is positioned on the heating object W1 side relative to the optical axis A1 of the first LED 5a, and this is explained below.

[0060] FIG. 5A is a diagram schematically illustrating the simulation conditions for this verification. In this verification, the illuminance distribution of heating light in the X direction, among the in-plane directions of a heating object W1 having a diameter of 300 mm, was verified. The first LEDs (5a, 5b) and the second LEDs 6 are both 1 mm square LEDs. Note that some of the first LEDs (5a, 5b) and some of the second LEDs 6 are not shown in FIG. 5A. The respective arrangements of the first LEDs (5a, 5b) and the second LEDs 6 will be described below.

[0061] FIG. 5A illustrates a normal line (hereinafter referred to as the "central axis R1" for convenience) passing through the center of the main surface W1a of the object to be heated W1. In this test, four first LEDs 5a were arranged on the -X side of the object to be heated W1. The first LED 5a closest to the object to be heated W1 in the X direction was arranged at a position 150 mm in the -X direction from the central axis R1. The distance between each of the first LEDs 5a was 3 mm. On the +X side of the object to be heated W1, first LEDs 5a were arranged in the same manner as on the -X side. In other words, eight first LEDs 5a were arranged in the X direction.

[0062] Four first LEDs 5b were arranged in an area facing the peripheral edge E1 on the -X side of the object to be heated W1. The first LED 5b closest to the central axis R1 in the X direction was arranged at a position 130 mm from the central axis R1 in the -X direction. The distance between each of the first LEDs 5b was 3 mm. On the +X side of the object to be heated W1, first LEDs 5b were arranged in the same manner as on the -X side. In other words, eight first LEDs 5b were arranged in the X direction.

[0063] Furthermore, 20 second LEDs 6 were arranged on the -X side of the central axis R1 in the region facing the central portion C1 of the heating object W1. The second LED 6 closest to the central axis R1 was arranged at a position 23 mm from the central axis R1 in the -X direction. The distance between each second LED 6 was 3 mm. Second LEDs 6 were also arranged on the +X side of the central axis R1, similar to the -X side. In other words, 40 second LEDs 6 were arranged in the X direction.

[0064] A lens 11a was disposed facing each first LED 5a. That is, eight lenses 11a were disposed in the X direction. The focal point F1a of the lens 11a was disposed at a position 1 mm away from the optical axis A1 of the first LED 5a toward the heating object W1. The distance D1 in the Z direction between the first LED 5a and the lens 11a was set to 0.5 mm. The length of the lens 11a in the X direction was set to 4 mm.

[0065] The distance between the first LED (5a, 5b) and the second LED 6 and the object to be heated W1 in the Z direction was set to 90 mm.

[0066] Under the above conditions, the illuminance distribution in the X direction of the heating light irradiated onto the main surface W1a of the heating object W1 was simulated (for convenience, this will be referred to as "simulation S11").

[0067] In addition, in this verification, as a comparative example, the illuminance distribution of the heating light irradiated onto the main surface W1a was simulated when the lens 11a was not placed (for convenience, referred to as "simulation S12").

[0068] 5B is a graph showing the results of this verification. In FIG. 5B, the horizontal axis represents the distance in the X direction from the center of the heating object W1, and the vertical axis represents the illuminance ratio of the heating light irradiated onto the heating object W1. The illuminance ratio was based on the illuminance at the edge position (150 mm) of the heating object W1 in simulation S12.

[0069] 5B, it can be seen that the placement of the lens 11a increases the illuminance of the heating light irradiated onto the peripheral edge of the heating object W1. This is thought to be because the focal point F1a of the lens 11b is positioned closer to the heating object W1 than the optical axis A1 of the first LED 5a, so that the heating light L1a incident on the lens 11a is guided toward the heating object W1.

[0070] [Verification 2] Next, we verified through simulation that the illuminance of the heating light irradiated to the peripheral edge E1 of the heating object W1 is increased by the lens 11b whose focus F1b is positioned on the optical axis A1 of the first LED 5b, and this is explained below.

[0071] FIG. 6A is a diagram schematically illustrating the simulation conditions for this verification. This verification differs from verification 1 in that the first LED 5a and lens 11a in verification 1 were removed, and a lens 11b was arranged relative to the first LED 5b. As shown in FIG. 6A, the focal point F1b of the lens 11b was arranged on the optical axis A1 of each first LED 5b. In other words, eight lenses 11b were arranged in the X direction. The distance between the first LED 5b and the lens 11b in the Z direction was the same as D1 in verification 1. The width of the lens 11b in the X direction was 4 mm. For convenience, the simulation for this configuration is referred to as "Simulation S21."

[0072] In addition, in this verification, as a comparative example, the illuminance distribution of the heating light irradiated onto the main surface W1a was simulated when the lens 11b was not placed (for convenience, referred to as "simulation S22").

[0073] 6B is a graph showing the results of this verification, following Fig. 5B. The illuminance ratio was based on the illuminance at the end position (150 mm) of the heating object W1 in simulation S22.

[0074] 6B, it can be seen that the provision of lens 11b increases the illuminance of the heating light irradiated onto the peripheral edge E1 of the heating object W1. This is thought to be because lens 11b reduces the divergence angle of the heating light L1b. More specifically, it is thought that if lens 11b were not provided, heating light directed in a direction different from the heating object W1 or heating light directed toward the central portion C1 would be guided to the peripheral edge E1.

[0075] In simulation S21, the illuminance ratio of the heating light decreases at a position approximately 100 mm from the heating object W1. However, as described above, the closer to the center C1 of the heating object W1, the lower the illuminance of the heating light required is compared to the illuminance of the heating light required at the edge of the peripheral edge E1. In other words, considering that heat is more difficult to dissipate from the inner region of the heating object W1 than from the edge region of the heating object W1, and that heating the edge region of the peripheral edge E1 heats the inner region through heat conduction from the edge region, it is preferable to increase the illuminance at the edge of the heating object W1 at the peripheral edge E1, as shown in simulation S21, for example.

[0076] [Verification 3] Next, the illuminance distribution of the heating light when the lens 11a and the lens 11b were arranged relative to the first LED 5a and the first LED 5b, respectively, was verified by simulation. This verification was carried out under the same conditions as in Verification 1, except that the lens 11b was additionally arranged relative to the first LED 5b. The arrangement of the lens 11b relative to the first LED 5b was the same as that of the lens 11b in Verification 2.

[0077] 7A is a diagram schematically illustrating the simulation conditions for this verification. As shown in FIG. 7A, in this verification, a lens 11a and a lens 11b were arranged relative to the first LED 5a and the first LED 5b, respectively. The arrangement of the lens 11a relative to the first LED 5a and the arrangement of the lens 11b relative to the first LED 5b are the same as those described in verifications 1 and 2. For convenience, the simulation related to this configuration is referred to as "simulation S31."

[0078] In this verification, the illuminance distribution of heating light irradiated onto the main surface W1a was simulated with the focal point F1a of the lens 11a positioned on the optical axis A1 of the first LED 5a (for convenience, this will be referred to as "Simulation S32"). Furthermore, as a comparative example, the illuminance distribution was simulated without the lens 11a and the lens 11b (for convenience, this will be referred to as "Simulation S33").

[0079] 7B is a graph showing the results of this verification, following the example of FIG. 5B. As can be seen from FIG. 7B, the illuminance of the heating light at the peripheral edge E1 of the heating target W1 is increased by placing the lenses 11a and 11b. This is thought to be because the heating light L1b emitted by the first LED 5b facing the peripheral edge E1 is focused on the peripheral edge E1 by the lens 11b. This point can be understood by comparing simulations S32 and S33.

[0080] Furthermore, as is clear from the results of simulation S31, by positioning the focal point F1a of the lens 11a closer to the object W1 than the optical axis A1 of the first LED 5a, the illuminance of the heating light irradiated onto the peripheral edge E1 of the object W1 is further increased. This result is consistent with the results of Verification 1.

[0081] In Simulations S31 and S32, the illuminance ratio of the heating light decreases at a position approximately 100 mm from the heating object W1. This point can be explained in the same way as in Simulation S21 in Verification 2. In other words, because the inner region of the heating object W1 is more easily heated than the region on the edge of the peripheral edge E1, it is preferable to increase the illuminance on the edge side of the heating object W1 at the peripheral edge E1, as shown in Simulations S31 and S32, for example.

[0082] [Summary of Verification] In the above verification, the illuminance distribution of the heating light in the X direction was simulated, but the same discussion as above can be made regarding directions parallel to the XY plane.

[0083] The above verification shows that the configuration described in the first embodiment allows more heating light to be irradiated onto the peripheral edge E1 of the heating object W1. In other words, the first embodiment provides a light heating device that can more efficiently increase the illuminance of heating light onto the peripheral edge E1 of the heating object W1.

[0084] [Second embodiment] A second embodiment of the light heating device according to the present invention will be described below with reference to Figures 8A and 8B, focusing on differences from the first embodiment. Figure 8A is a side cross-sectional view of the light heating device according to the second embodiment. Figure 8B is an enlarged view of a portion of Figure 8A.

[0085] In the above description, the first optical system 10 is described as being composed of lenses (11a, 11b). However, the first optical system 10 may be composed of a prism 14a that refracts the heating light L1a. The prism 14a is formed on the −Z side of the flat glass 9, as shown in FIG. 8B .

[0086] 8B , the prism 14a has a light exit surface 16 that is inclined with respect to the main surface W1a of the object to be heated W1, and a light entrance surface 15 that is formed by the main surface on the +Z side of the flat glass 9. The light exit surface 16 of each prism 14a is positioned on the optical axis A1 of the corresponding first LED 5a.

[0087] The light exit surface 16 of the prism 14a is shaped so that the distance between the light exit surface 16 and the object to be heated W1 in the Z direction decreases as the light exit surface 16 approaches the object to be heated W1 in the direction parallel to the XY plane.

[0088] In this embodiment, a second optical system 20 that refracts the heating light L2 is disposed for some of the second LEDs 6. The second optical system 20 is configured with a prism 21 that refracts the heating light L2. As shown in FIG. 8A , the prism 21 is formed on the main surface on the −Z side of the flat glass 9.

[0089] The prisms 21 each have a light exit surface 23 that is inclined with respect to the main surface W1a of the object to be heated W1, and a light entrance surface 22 that is formed by the main surface on the +Z side of the flat glass 9 (see FIG. 8B ). The light exit surface 23 of each prism 21 is positioned on the optical axis A2 of the corresponding second LED 6.

[0090] The light exit surface 23 of the prism 21 is shaped so that the distance between the light exit surface 23 and the object to be heated W1 in the Z direction decreases as the light exit surface 23 approaches the peripheral edge E1 of the object to be heated W1 in the direction parallel to the XY plane.

[0091] 8B schematically illustrates the propagation of the heating light (L1a, L1b) emitted by the first LEDs (5a, 5b) and the heating light L2 emitted by the second LED 6. As shown in FIG. 8B, the prism 14a refracts the incident heating light L1a toward the heating object W1. This increases the amount of heating light L1 irradiated onto the peripheral edge E1 of the main surface W1a of the heating object W1.

[0092] The prism 21 also refracts the incident heating light L2 toward the peripheral edge E1 of the main surface W1a (see FIG. 8B), thereby increasing the amount of heating light L2 irradiated onto the peripheral edge E1 of the main surface W1a of the heating target W1.

[0093] Although not shown in the figure, the heating light L2 emitted by some of the second LEDs 6 where the second optical system 20 is not arranged is irradiated onto a wide area including the central portion C1, thereby preventing the illuminance from becoming locally high in some areas of the central portion C1, which can be discussed in a similar manner to that described with reference to Figure 4.

[0094] The refractive index of the prisms (14a, 21) and the angle of the light exit surface (16, 23) relative to the heating object W1 can be adjusted as appropriate.

[0095] The arrangement of the first LEDs (5a, 5b) and the second LEDs 6 can be discussed in the same manner as in the first embodiment.

[0096] In this embodiment, the first optical system 10 is configured by the prism 14a, but the first optical system 10 may be configured by, for example, a Fresnel lens. The same applies to the second optical system 20.

[0097] 9 is a side cross-sectional view of another example of the configuration of the light heating device. As shown in FIG. 9, as described in the first embodiment, a lens 11b may be disposed relative to the first LED 5b. As described in Verification 2, this allows the heating light L1b emitted by the first LED 5b to be guided to the peripheral end E1 with a reduced divergence angle, thereby further increasing the illuminance at the peripheral end E1.

[0098] Furthermore, the second optical system 20 described in the second embodiment may be added to the configuration described with reference to FIG.

[0099] (Modifications) Modifications of the light heating device 1 will now be described.

[0100] <1> The second optical system 20 may be a converging optical system that reduces the divergence angle of the heating light L2. For example, the second optical system 20 may be configured with a convex lens. Fig. 10A is a side cross-sectional view of a modified light heating device 1 shown in Fig. 1. Fig. 10B is an enlarged view of a portion of Fig. 10A. As shown in Figs. 10A and 10B, a lens 24 may be disposed relative to the second LED 6.

[0101] 10B , the focal point F2 of the lens 24 is located on the peripheral edge E1 side of the object to be heated W1 with respect to the optical axis A2 of the second LED 6 on which the lens 24 is disposed. This allows the heating light L2 emitted by the second LED 6 to be guided toward the peripheral edge E1 side while reducing the divergence angle of the heating light L2.

[0102] Furthermore, considering the results of the above verification 1, it can be understood that by positioning the focus F2 of the lens 24 closer to the peripheral edge E1 of the object to be heated W1 than the optical axis A2 of the second LED 6, the heating light L2 incident on the lens 24 can be guided toward the peripheral edge E1.

[0103] In this modified example, the second optical system 20 may be a prism 21. However, from the viewpoint of reducing the divergence angle of the heating light L2 and increasing the amount of heating light L2 guided to the peripheral end E1, it is preferable that the second optical system 20 be configured with a lens 24.

[0104] Note that, if the heating light (L1a, L1b) emitted by the first LEDs (5a, 5b) can sufficiently heat the peripheral edge E1 of the heating target W1, there is no need for the second optical system 20. In other words, in the present invention, the second optical system 20 has an optional configuration.

[0105] <2> Figure 11 is a side cross-sectional view of a modified example of the optical heating device, shown in accordance with Figure 1. In the above, it has been described that the first LED 5a is provided, but as shown in Figure 11, it is optional whether or not the light source unit 3 includes the first LED 5a. It can be understood from Verification 2 above that this modified example increases the illuminance at the peripheral end E1 of the heating target W1.

[0106] The configuration of FIG. 11 does not have a first LED 5a located outside the heating target W1 when viewed in the Z direction, and the dimensions of the light heating device 1 can be easily reduced.

[0107] <3> Fig. 12 is a side cross-sectional view of a modified example of the light heating device, shown similarly to Fig. 1. As shown in Fig. 12, a first optical system 10 may be arranged for a plurality of first LEDs 5a. More specifically, the first optical system 10 is composed of a lens 17 having a shape of a revolution body centered on a central axis R1.

[0108] The light exit surface 17a of the lens 17 is formed by a part of an ellipsoidal sphere, and the focal point (not shown) of the lens 17 is located on the central axis R1. In other words, the focal point of the lens 17 is located closer to the object to be heated W1 than the optical axis A1 of the first LED 5a, and the heating light L1a is guided so as to converge toward the focal point, thereby increasing the amount of heating light irradiated onto the peripheral edge E1 of the object to be heated W1.

[0109] 12, with respect to the traveling direction of the heating light La1, a collimating lens (not shown) that converts the heating light La1 into parallel light may be disposed between the first LED 5a and the lens 17. From this perspective, the heating light L1a is illustrated as parallel light in FIG.

[0110] <4> Fig. 13A is a side cross-sectional view of a modified example of the light heating device 1. Fig. 13B is a plan view of Fig. 13A when viewed in the Z direction. As shown in Figs. 13A and 13B , the flat glass 9 may spatially separate the internal space of the chamber 8 into spaces S1 and S2. Space S1 is the space in which the object to be heated W1 in the chamber 8 is located, and space S2 is the space in which the light source unit 3 in the chamber 8 is located. In this case, the flat glass 9 corresponds to the "partition plate."

[0111] 13A, the optical heating device 1 has an inlet 30 for introducing a predetermined process gas G1 into the space S1 and an exhaust port 31 for exhausting the process gas G1. According to the optical heating device 1 of this embodiment, the heating target W1 can be heated while the predetermined process gas G1 is brought into contact with the main surface W1a of the heating target W1.

[0112] The gas species contained in the process gas G1 can be appropriately selected depending on the treatment to be performed on the heating object W1. If the process gas G1 contains, for example, hydrogen chloride or ammonia, contact of the process gas G1 with the first LEDs (5a, 5b) may cause deterioration or failure of the first LEDs (5a, 5b). However, according to this modification, the flat glass 9 spatially separates the spaces S1 and S2, preventing contact between the first LEDs (5a, 5b) and the process gas G1, thereby suppressing deterioration of the first LEDs (5a, 5b) due to the process gas G1. The same discussion can be applied to the second LED 6.

[0113] <5> Figure 14 is a plan view showing another example of the arrangement of the first LEDs (5a, 5b) and the second LEDs 6. The first LEDs (5a, 5b) and the second LEDs 6 may be uniformly arranged on the main surface 7a of the LED substrate 7. "Uniformly arranged" means that, as shown in Figure 14, the distance D2 between the multiple LEDs in the X direction is constant and the distance D3 between the multiple LEDs in the Y direction is constant. The distances D2 and D3 may be the same or different. The uniform arrangement of the first LEDs (5a, 5b) and the second LEDs 6 facilitates the design and manufacture of the LED substrate 7.

[0114] <6> Figure 15 is a side cross-sectional view of a modified example of the light heating device 1. In the above description, the first LED 5a is described as being arranged on the main surface 7a of the LED substrate 7 parallel to the XY plane. However, the present invention is not limited to whether the first LED 5a is arranged on a plane parallel to the XY plane.

[0115] 15 , the first LED 5 a may be disposed on a main surface 7 b of the LED substrate 7 that is inclined with respect to the XY plane. In this modification, an example is shown in which the flat glass 9 is fixed to the LED substrate 7 via a support member 32.

[0116] 15, some of the first LEDs 5a are arranged at an angle with respect to the XY plane, but all of the first LEDs 5a may be arranged at an angle with respect to the XY plane. Note that the heating light L1b and the heating light L2 are not shown in FIG.

[0117] 16 is a side cross-sectional view of a modified example of the optical heating device 1. As shown in FIG. 16, the lens 11a may be positioned relative to the first LED 5a arranged on the main surface 7b of the LED substrate 7 so that the focal point F1a is located on the optical axis A1 of the first LED 5a. According to this modified example, the heating light L1a emitted by the first LED 5a can be irradiated onto the peripheral edge E1 of the heating object W1 while reducing the divergence angle of the heating light L1a. The focal length of the lens 11a may be adjusted as appropriate.

[0118] <7> Fig. 17 is a side cross-sectional view showing a modified example of the light heating device 1. Fig. 18 is a plan view when Fig. 17 is viewed in the Z direction. As shown in Fig. 17, the heating target W1 may be heated while being rotated in the XY plane around the central axis R1 by the support unit 2.

[0119] In this modification, the first LEDs (5a, 5b) and the second LED 6 are turned on while the heating object W1 is rotated around the central axis R1. By rotating the heating object W1 around the central axis R1, the heating light is uniformly irradiated in the circumferential direction of the main surface W1a of the heating object W1.

[0120] In this modified example, the support unit 2 may have any configuration as long as it can rotate the heating object W1 about the central axis R1 while supporting the heating object W1. As an example, the rotation speed of the heating object W1 is set to 20 rpm to 100 rpm. Note that, although the heating object W1 rotates in this modified example, the light source unit 3 and the flat glass 9 fixed to the LED substrate 7 via the support member 32 to the light source unit 3 may also rotate about the central axis R1 relative to the heating object W1.

[0121] Furthermore, for example, in this modified example, by arranging multiple second LEDs 6 and arranging a second optical system 20 for some of the second LEDs 6, the heating light L2 emitted by some of the second LEDs 6 can be guided toward the peripheral end E1, while the heating light L2 emitted by other second LEDs 6 for which a second optical system 20 is not arranged can be irradiated onto a wide area including the central portion C1.

[0122] <8> In the above description, the first optical system 10 or the second optical system 20 is described as being formed integrally with the flat glass 9. However, the first optical system 10 may be formed as a separate member from the flat glass 9. The same applies to the second optical system 20.

[0123] <9> Furthermore, in the above description, the optical heating device 1 has been described as having the chamber 8. However, for example, if the process gas G1 is not introduced and the heating target W1 is heated in an atmospheric environment, the chamber 8 is not necessary. In other words, it is optional whether or not the optical heating device 1 has the chamber 8.

[0124] <10> The configurations of the above embodiment and each modification can be realized by combining them as appropriate.

[0125] DESCRIPTION OF SYMBOLS 1: Optical heating device 2: Support unit 3: Light source unit 4: Second LED 5a, 5b: First LED 6: Second LED 7: LED substrate 8: Chamber 9: Flat glass 10: First optical system 11a, 11b, 17: Lens 12, 15: Light incident surface 13, 16, 17a: Light exit surface 14a: Prism 20: Second optical system 21: Prism 22: Light incident surface 23: Light exit surface 24: Lens 30: Inlet 31: Exhaust port 32: Support member A1, A2: Optical axis C1: Center E1: Peripheral end F1a, F1b, F2: Focus G1: Process gas L1a, L1b, L2: Heating light R1: Central axis S1, S2: Space W1: Heating object

Claims

1. An optical heating device that irradiates a heated object with light to perform a heating process on the heated object, comprising: a support unit that supports the heated object; a light source unit having a plurality of first LEDs that are located outside the center of the heated object when viewed in the normal direction of a main surface of the heated object supported by the support unit, and a plurality of second LEDs that are located in an area facing the center of the heated object; and a first optical system that is disposed between the heated object and the light source unit in the normal direction of the main surface of the heated object, wherein the first optical system refracts at least a portion of the first heating light emitted by the first LEDs and directs it toward the peripheral edge of the heated object.

2. The optical heating device described in claim 1, characterized in that the multiple first LEDs include LEDs located outside the peripheral edge of the object to be heated when viewed in the normal direction, and the first optical system refracts heating light emitted by the LEDs located outside the peripheral edge of the object to be heated when viewed in the normal direction, and directs the heating light toward the peripheral edge of the object to be heated.

3. The optical heating device described in claim 2, wherein the first optical system is a converging optical system that is individually arranged with respect to an LED that is located outside the peripheral edge of the object to be heated when viewed in the normal direction and reduces the divergence angle of the incident heating light, and wherein, when viewed in the normal direction, the focus of the first optical system is located on the side of the object to be heated rather than the center of the light-emitting surface of the LED on which the first optical system is arranged.

4. The optical heating device described in claim 2, characterized in that the first optical system is a converging optical system arranged for multiple LEDs located outside the peripheral edge of the object to be heated when viewed in the normal direction, and the focus of the first optical system is located on the side of the object to be heated rather than the center of the light-emitting surface of the multiple LEDs in which the first optical system is arranged when viewed in the normal direction.

5. The optical heating device described in claim 1, characterized in that the multiple first LEDs include LEDs located in an area facing the peripheral edge of the object to be heated, and the first optical system is a converging optical system that reduces the divergence angle of the heating light emitted by the LEDs located in the area facing the peripheral edge of the object to be heated.

6. The optical heating device according to claim 5, wherein the plurality of first LEDs are arranged in an area facing the peripheral edge of the object to be heated.

7. An optical heating device as described in any one of claims 1 to 6, characterized in that it is provided with a second optical system that refracts the second heating light emitted by the second LED and directs it toward the peripheral edge of the object to be heated.

8. The optical heating device described in any one of claims 1 to 6, wherein the light source unit further comprises an LED board having a mounting surface parallel to the main surface of the object to be heated, and the LED board has the first LED and the second LED mounted on the mounting surface.

9. An optical heating device as described in any one of claims 1 to 6, further comprising: a chamber that houses the support unit and the light source unit; and a partition plate that separates, within the chamber, a space in which the object to be heated is located from a space in which the light source unit is located, and the first optical system is formed integrally with the partition plate.

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