Light heating device and heat treatment method

Abstract

To provide an optical heating device which includes an LED element as a light source for heating, and in which the heating of the LED element is suppressed, which has improved reliability as a result, and a heating treatment method.SOLUTION: An optical heating device comprises a support member on which a treatment-object substrate is mounted, and a plurality of light source units each of which includes an LED substrate on which an LED element group is loaded. A first principal surface of the LED substrate and a second principal surface of the treatment-object substrate mounted on the support member are non-parallel. When an angle formed between the first principal surface and the second principal surface is defined as θ, an interval between the treatment-object substrate and a first LED element which is loaded on the LED substrate and positioned closest to the second principal surface with respect to a normal direction of the second principal surface is defined as D1 and an interval between the first LED element and a second LED element which is loaded on the LED substrate and positioned farthest from the second principal surface with respect to the normal direction is defined as D2, the plurality of light source units is disposed in such a manner that each of the light source units satisfies a predetermined relational expression.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a light heating device and a heat treatment method. [Background technology]

[0002] In the semiconductor manufacturing process, various heat treatments such as film formation, oxidation / diffusion, modification, and annealing are performed on substrates such as semiconductor wafers. These treatments are often performed using heat treatment methods that use light irradiation, which allows for non-contact processing.

[0003] Known devices for heat-treating substrates include those equipped with lamps such as halogen lamps or solid-state light sources such as LEDs, which irradiate the substrates with light for heating. For example, Patent Document 1 listed below describes a wafer heating unit equipped with multiple LEDs. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-009927 Summary of the Invention [Problem to be solved by the invention]

[0005] Examples of substrates that can be heat-treated by light irradiation include semiconductor wafers and glass substrates. When these substrates are irradiated with light emitted from a heating light source, they absorb a portion of the light and generate heat. The heat thus generated heats the substrates.

[0006] However, most objects do not absorb all of the light that is irradiated onto them, but rather absorb part of the light and reflect the other part. For this reason, a substrate to be heat-treated absorbs part of the light that is irradiated onto it and reflects the other part.

[0007] The heating device described in Patent Document 1 is configured so that the first main surface on which the LEDs of the substrate constituting the heating LED lamp are placed and the second main surface, which is the main surface onto which the heating light of the substrate to be processed is irradiated, are parallel within the heating furnace body.

[0008] When this heating device configuration is employed, the light emitted from the LED element travels toward the second main surface of the substrate to be processed, and of the light that reaches the second main surface of the substrate to be processed, part is absorbed by the substrate to be processed, and the other part is reflected by the second main surface so as to travel toward the LED element.

[0009] When the light reflected by the second main surface reaches the LED element or its vicinity, a portion of the light is absorbed by the LED element or the substrate on which the LED element is mounted, and the LED element or the substrate is heated in accordance with the energy of the absorbed light.

[0010] Heating devices for heating substrates are equipped with hundreds to thousands of LED elements to heat the substrates to several hundred degrees. Even when the light source is composed of multiple light source units, tens to hundreds of LED elements are often densely packed in each light source unit to more efficiently heat the substrates. Therefore, even light reflected from the second main surface of the substrate and returned to the light source unit may have enough energy to heat the LED elements mounted in the light source unit to several hundred degrees. Such excessive heating can significantly reduce the luminous efficiency and shorten the lifespan of the LED elements mounted in the light source unit, and even damage the LED elements themselves.

[0011] Furthermore, LED elements are often bonded to the substrate using solder or silver paste. Therefore, if the LED element is heated to the melting temperature of the solder or silver paste, there is a risk that the LED element will come off the substrate and fall. Both of these phenomena pose major problems in terms of the reliability of the heating device.

[0012] In view of the above-mentioned problems, an object of the present invention is to provide a light heating device and a heat treatment method that are improved in reliability by suppressing heating of an LED element that is a heating light source. [Means for solving the problem]

[0013] The light heating device of the present invention is A light heating device that heats a substrate to be processed by irradiating a second main surface of the substrate to be processed with light, a support member on which the substrate to be processed is placed; A plurality of light source units including an LED substrate on which a group of LED elements is mounted, a first main surface of the LED substrate and a second main surface of the substrate to be processed placed on the support member are non-parallel to each other; An optical heating device characterized in that each of the multiple light source units is arranged to satisfy the following formula (1): when the angle between the first main surface and the second main surface is θ, the distance between the substrate to be treated and a first LED element mounted on the LED substrate and located closest to the second main surface in the normal direction to the second main surface is D1, and the distance between the first LED element mounted on the LED substrate and located farthest from the second main surface in the normal direction is D2. 2tan2θ / cosθ≧D2 / D1 (1)

[0014] In this specification, the distance D1 between the LED element of the light source unit and the substrate to be processed is defined as the distance between the center of the light emitting surface of the LED element and the substrate to be processed.

[0015] In this specification, the distance between the first LED element and the second LED element is defined as the distance between the centers of the LED elements when viewed from a direction perpendicular to the first main surface of the substrate. When a single light source unit includes multiple first LED elements and multiple second LED elements, the distance D2 corresponds to the shortest distance between each combination of the first LED elements and the second LED elements.

[0016] With the above configuration, the chief ray of light emitted from an LED element mounted in the light source unit that is arranged at least closer to the second LED element than the first LED element, when reflected by the second main surface of the substrate to be treated, travels outside the area where the LED elements on the substrate of the light source unit are arranged, or toward the outside of the light source unit.

[0017] Therefore, the amount of light that is emitted from the LED element of the light source unit, reflected by the second main surface of the substrate to be treated, and returned to the LED element or its vicinity is reduced. In this way, the LED element mounted on the light source unit is prevented from being heated by the light reflected by the second main surface of the substrate to be treated. Note that the "chief ray" refers to the ray of light that exhibits the highest intensity among the light emitted from the light source.

[0018] The relationship between the derivation of the above formula (1) and the effects of the above configuration will be described in detail in the section "Mode for Carrying Out the Invention" with reference to the drawings and the like.

[0019] The light heating device is An angle adjustment mechanism may be provided that adjusts the angle θ by changing the position of the LED substrate.

[0020] Furthermore, the light heating device A control unit may be provided that determines the value of the angle θ based on the separation distance D1 and the separation distance D2, and drives the angle adjustment mechanism based on the determined value of the angle θ.

[0021] With the above configuration, the angle θ between the first main surface and the second main surface can be adjusted appropriately depending on the shape of the substrate to be processed and the setting of the separation distance D1 during the heat treatment of the substrate to be processed.

[0022] Furthermore, with the above configuration, the optical heating device can be configured such that, for example, the control unit determines the angle θ that satisfies the condition of equation (1) above based on the values ​​of the predetermined separation distance D1 and separation distance D2, and automatically adjusts the position of the LED substrate to the optimal position.

[0023] One method for determining the angle θ is to store a table in advance that calculates the optimal value of the angle θ for each combination of the separation distance D1 and the separation distance D2, and then, when the separation distance D1 and the separation distance D2 are input, select the corresponding value of the angle θ from the table.

[0024] The light heating device is An angle sensor may be provided for measuring the angle θ formed between the first main surface and the second main surface.

[0025] With the above configuration, the light heating device can adjust the position of the light source unit while checking whether the arrangement position of the light source unit satisfies the condition of the above formula (1).

[0026] Furthermore, with the above configuration, if the light heating device 1 receives a large impact and the position of the light source unit shifts, it is possible to detect a state in which the condition of the above formula (1) is no longer satisfied.

[0027] In the above-mentioned light heating device, The support member may include a rotation mechanism that rotates the substrate to be processed about an axis that is perpendicular to the second main surface and passes through the center of the second main surface.

[0028] With the above configuration, the optical heating device can irradiate the substrate to be processed with heating light emitted from the light source unit while rotating the substrate to be processed placed on the support member. By irradiating the substrate to be processed with heating light while rotating the substrate to be processed, the amount of light irradiated onto the second main surface of the substrate to be processed is made uniform in the circumferential direction of the second main surface. Therefore, uneven heating of the substrate to be processed is suppressed.

[0029] In the above-mentioned light heating device, The LED elements mounted on the LED substrate may emit light with a peak wavelength in the range of 300 nm to 1000 nm.

[0030] In particular, semiconductor wafers made of silicon (Si) (hereinafter referred to as "silicon wafers") have a high absorptivity for light in the wavelength range from ultraviolet light to visible light, but the absorptivity drops sharply when the wavelength is longer than 1100 nm. As shown in Figure 4, which is referred to in the explanation of the "Mode for Carrying Out the Invention," when a silicon wafer is irradiated with light having a wavelength of 1100 nm or longer, the absorptivity is approximately 50% or less.

[0031] As mentioned above, most objects do not absorb all of the light that is irradiated onto them, but rather absorb some of the light and reflect the other part. In other words, according to the graph shown in Figure 4, when a silicon wafer is irradiated with light having a wavelength of 1100 nm, more than 50% of the irradiated light is transmitted or reflected without being absorbed.

[0032] If the substrate has a high reflectivity, a large amount of light will be reflected by the second main surface of the substrate. For this reason, it is preferable that the peak wavelength of the light emitted from the LED element is 1000 nm or less, at which point the silicon wafer has an absorptivity of 50% or more.

[0033] Furthermore, the absorption rate of silicon wafers for light with wavelengths of less than 300 nm drops to approximately 10% at its lowest. Therefore, to ensure an absorption rate of at least 25%, it is preferable that the peak wavelength of the light emitted from the LED element be 300 nm or longer.

[0034] Therefore, by adopting LED elements with a peak wavelength in the above wavelength range for the LED elements mounted in the light source unit, the proportion of the light reflected by the second main surface of the substrate to be treated of the light emitted from the light source unit and irradiated onto the substrate to be treated is reduced, thereby preventing the LED elements mounted in the light source unit from being irradiated and heated.

[0035] Furthermore, in the above-mentioned light heating device, The LED elements mounted on the LED substrate may emit light with a peak wavelength in the range of 800 nm to 900 nm.

[0036] As shown in Figure 4, silicon (Si) has a small change in absorptance with respect to wavelength fluctuations for light in the wavelength range of 800 nm to 900 nm. Therefore, by using this wavelength range, uneven heating is less likely to occur even if the wavelength of light irradiated to each irradiation area of ​​the silicon wafer varies slightly.

[0037] Therefore, with the above configuration, it is possible to configure a light heating device that is less affected by variations in the peak wavelength of the light emitted by the LED elements during the heat treatment of silicon wafers.

[0038] The heat treatment method of the present invention comprises: A heat treatment method for heating a substrate to be treated placed on a support member by irradiating the substrate with light emitted from a plurality of light source units, each of which includes an LED substrate on which a group of LED elements is mounted, comprising: a first main surface of the LED substrate and a second main surface of the substrate to be processed placed on the support member are non-parallel to each other; a heat treatment method comprising: irradiating the substrate to be treated with light emitted from each of the plurality of light source units arranged to satisfy the following formula (1): where θ is the angle formed between the first main surface and the second main surface, D1 is the distance between the substrate to be treated and a first LED element mounted on the LED substrate and located closest to the second main surface in the normal direction to the second main surface, and D2 is the distance between the first LED element and a second LED element mounted on the LED substrate and located farthest from the second main surface in the normal direction to the second main surface. 2tan2θ / cosθ≧D2 / D1 (1)

[0039] The heat treatment method is The method may include determining the value of the angle θ based on the separation distance D1 and the separation distance D2, and changing the position of the LED substrate based on the determined value of the angle θ. [Effects of the Invention]

[0040] According to the present invention, the heating of the LED element serving as the heating light source is suppressed, thereby realizing a light heating device and a heat treatment method with improved reliability. [Brief explanation of the drawings]

[0041] [Figure 1] FIG. 2 is a schematic cross-sectional view of an embodiment of a light heating device when viewed in the Y direction. [Figure 2] This is a drawing of the frame in Figure 1 as seen from the -Z side. [Figure 3] 2 is a view of the chamber of FIG. 1 as seen from the +Z side. [Figure 4] 1 is a graph showing the relationship between the wavelength of light and the absorptance when the temperature of silicon (Si) is 543K. [Figure 5] 3 is a schematic diagram for explaining the configuration of a light source unit and the positional relationship between the light source unit and a substrate to be processed. [Figure 6] FIG. 10 is a schematic cross-sectional view of another embodiment of the light heating device when viewed in the Y direction. DETAILED DESCRIPTION OF THE INVENTION

[0042] The light heating device and heat treatment method of the present invention will be described below with reference to the drawings. Note that the following drawings relating to the light heating device are all schematic illustrations, and the dimensional ratios and numbers in the drawings do not necessarily correspond to the actual dimensional ratios and numbers.

[0043] Fig. 1 is a schematic cross-sectional view of a first embodiment of a light heating device 1 when viewed in the Y direction. Fig. 2 is a drawing of the frame 11 in Fig. 1 when viewed from the -Z side, and Fig. 3 is a drawing of the chamber 2 in Fig. 1 when viewed from the +Z side. As shown in Fig. 1, the light heating device 1 includes a chamber 2, a light source unit 10, and a frame 11. Note that in Fig. 3, a translucent window 2a, which will be described later, is not hatched so that the structure inside the chamber 2 can be seen.

[0044] In the following description, as shown in FIG. 3, a plane parallel to the second main surface W1a of the substrate W1 to be processed, which is the target of heat treatment and accommodated in the chamber 2, is defined as the XY plane, and as shown in FIG. 1, a direction perpendicular to the XY plane is defined as the Z direction.

[0045] Also, when expressing a direction, if a distinction is made between positive and negative directions, the direction is written with a positive or negative sign, such as "+Z direction" and "-Z direction," and when a direction is expressed without distinguishing between positive and negative directions, it is simply written as "Z direction."

[0046] Furthermore, in the explanation of the first embodiment, it is assumed that the substrate W1 to be processed is a silicon wafer, but it is also envisioned that the optical heating device 1 of the present invention can be used to heat a substrate W1 to be processed other than a silicon wafer (for example, a glass substrate, etc.).

[0047] As shown in FIG. 1, the chamber 2 includes a support member 3 for placing a substrate W1 to be processed therein, and a light-transmitting window 2a for guiding light emitted from the light source unit 10 to the inside.

[0048] As shown in FIGS. 1 and 3, the support member 3 has a structure in which a plurality of protrusions 3b are provided on a base 3a, and the substrate W1 to be processed is placed and supported on the tips of the plurality of protrusions 3b.

[0049] 1, the support member 3 of this embodiment is provided with a rotation mechanism using a plurality of rollers 3c, and when heat treatment is performed, the substrate W1 to be processed is rotated on the XY plane around an axis z1 that passes through the center of the support member 3 in the Z direction, as shown in Fig. 3. Note that the support member 3 does not need to be configured to rotate the substrate W1 to be processed when the light source unit 10 is configured to irradiate the second main surface W1a of the substrate W1 to be processed with light uniformly in the circumferential direction.

[0050] As shown in Fig. 1, the light source unit 10 includes a plurality of LED elements 10a that emit light for heating, and an LED substrate 10b on which the plurality of LED elements 10a are mounted. Fig. 1 schematically illustrates only the chief ray L1 of the light emitted from the LED elements 10a.

[0051] In the light source unit 10 of this embodiment, LED elements 10a that emit infrared light with a peak wavelength of 850 nm are arranged in the X and Y directions on a first main surface 10p of an LED substrate 10b.

[0052] 2, the first main surface 10p of the LED substrate 10b is configured to have a rectangular shape, but the shape of the LED substrate 10b is arbitrary. Also, the arrangement of the LED elements 10a on the LED substrate 10b does not need to be aligned in the X and Y directions, and may be adjusted appropriately depending on the expected temperature distribution during the heat treatment of the substrate W1 to be treated.

[0053] Fig. 4 is a graph showing the relationship between light wavelength and absorptance when the temperature of silicon (Si) is 543 K. The peak wavelength of the light emitted by LED element 10a can be set arbitrarily, but as shown in Fig. 4, in order to ensure an absorptance of at least 25%, i.e., a reflectance of at least 75%, the peak wavelength is preferably 300 nm to 1000 nm, and more preferably 350 nm to 950 nm.

[0054] Furthermore, as shown in Figure 4, silicon (Si) has a small change in absorptance with respect to wavelength fluctuations for light with a wavelength in the range of 800 nm to 900 nm. Therefore, from the viewpoint of suppressing uneven heating, it is more preferable that the light emitted by the LED elements 10a mounted in the light source unit 10 has a peak wavelength of 800 nm to 900 nm, and particularly preferably 820 nm to 880 nm.

[0055] 1, the frame 11 in this embodiment is provided with an adjustment screw 11a as an angle adjustment mechanism for adjusting the tilt angle θ of the light source unit 10 so as to change the emission direction of light emitted from the LED elements 10a. The frame 11 also has a support wall 11b for preventing the position of the light source unit 10 from shifting when the tilt of the light source unit 10 is adjusted.

[0056] The frame 11 may be configured to fix the light source unit 10 at a predetermined angle θ without including the adjustment screw 11a and the support wall 11b. As the angle adjustment mechanism, for example, a mechanism such as a piezoelectric actuator or a micrometer head with an encoder may be used.

[0057] The frame 11 in this embodiment is a member for supporting a plurality of light source units 10. As shown in Fig. 1, the frame 11 is adjusted by an adjustment screw 11a so that a first main surface 10p of an LED substrate 10b included in each light source unit 10 is inclined at an angle θ with respect to the XY plane.

[0058] As shown in FIG. 1, in the frame 11 of this embodiment, the first main surface 10p of the LED substrate 10b is aligned with the XY plane, and the light source unit 10 is tilted by rotating it by an angle θ around the Y axis as the axis of rotation; however, the axis of rotation can be chosen arbitrarily as long as it is parallel to the XY plane.

[0059] The conditions for the angle θ will be explained below.

[0060] 5 is a schematic diagram for explaining the configuration of the light source unit 10 and the positional relationship between the light source unit 10 and the substrate W1 to be processed. For convenience of explanation, the configuration shown in Fig. 5 is illustrated with different angles θ between the first main surface 10p and the second main surface W1a, the number of LED elements 10a mounted on the light source unit 10, and the size ratio between the light source unit 10 and the substrate W1 to be processed, compared to Fig. 1.

[0061] The light source unit 10 is arranged so that the tilt angle θ satisfies the above formula (1), where D1 is the distance between the first LED element 10a1, which is located closest to the second main surface W1a of the LED elements 10a mounted on the LED substrate 10b, and the processed substrate W1, and D2 is the distance between the second LED element 10a2, which is located farthest from the second main surface W1a of the LED elements 10a mounted on the LED substrate 10b, and the first LED element 10a1. Just to be sure, the above formula (1) is presented again. 2tan2θ / cosθ≧D2 / D1 (1)

[0062] Specifically, the light source unit 10 in this embodiment is configured so that θ is 20.6°, D2 is 16 mm, and D1 is 40 mm.

[0063] The process of deriving the above formula (1) will be explained below. Note that the following explanation will be made on the assumption that the chief ray L1 is not absorbed by the second main surface W1a of the substrate to be processed W1 and is specularly reflected.

[0064] 5, let P1 be the point at which chief ray L1 of light emitted from first LED element 10a1, after being reflected by second main surface W1a of target substrate W1, reaches surface A1, which is an extension of light-emitting surface 10c of LED element 10a. Let R be the distance between the center of light-emitting surface 10c of first LED element 10a1 and point P1, and let E be the distance R in the Z direction. Let B be the distance D2 in the Z direction.

[0065] 5, the chief ray L1 of the light emitted from the first LED element 10a1 travels toward the substrate W1 to be processed (-Z side) and then reaches the second main surface W1a. Here, the distance traveled by the chief ray L1 from the time it is emitted from the first LED element 10a1 until it reaches the second main surface W1a of the second main surface W1a is defined as S.

[0066] The chief ray L1 is incident on the second principal surface W1a at an incident angle θ and is reflected at a reflection angle θ. Thereafter, the chief ray L1 travels toward the light source unit 10 (+Z side) and eventually reaches a point P1.

[0067] The traveling distance S of the chief ray L1 is shortest for the chief ray L1 emitted from the first LED element 10a1, and becomes longer for the LED element 10a closer to the second LED element 10a2. In other words, in terms of the X direction, the closer the LED element 10a is to the second LED element 10a2, the longer the distance traveled in the +X direction before reaching surface A1.

[0068] From the above relationship, if point P1, the arrival point of chief ray L1, is closer to second LED element 10a2 than midpoint C1 between first LED element 10a1 and second LED element 10a2, as described above, chief ray L1 of light emitted from LED element 10a closer to second LED element 10a2 will reach at least an area of ​​LED substrate 10b where LED element 10a is not arranged. In other words, more than half of the light emitted from LED element 10a and reflected from second main surface W1a toward LED substrate 10b can be reflected outside LED substrate 10b, and as a result, LED element 10a is prevented from being heated by light reflected from second main surface W1a.

[0069] The condition for point P1 to be closer to second LED element 10a2 than midpoint C1 between first LED element 10a1 and second LED element 10a2 is given by the following formula (2). 2E≧B (2)

[0070] As shown in Figure 5, the relationship between distance E, distance R, and angle θ is expressed as E = R × sin θ. Similarly, the relationship between distance B, separation distance D2, and angle θ is expressed as B = D2 × sin θ. When these relational expressions are substituted into equation (2) above and rearranged, it becomes equation (3) below. 2R≧D2 (3)

[0071] Furthermore, as shown in Figure 5, the relationship between the distance R, the travel distance S, and the angle θ is expressed as R = S × tan 2 θ. When this relational expression is substituted into the above equation (3), the following equation (4) is obtained. 2(S×tan2θ)≧D2 (4)

[0072] Finally, as shown in FIG. 5, the relationship between the travel distance S, the separation distance D1, and the angle θ is expressed as S=D1 / cosθ, and therefore, when this relational expression is substituted into the above equation (4) and rearranged, it becomes the above equation (1).

[0073] With the above configuration, the chief ray L1 of light emitted from the LED element 10a mounted on the light source unit 10, which is arranged at least closer to the second LED element 10a2 than the first LED element 10a1, is reflected by the second main surface W1a of the substrate W1 to be processed, and travels outside the area where the LED element 10a is arranged on the LED substrate 10b of the light source unit 10, or toward the outside of the light source unit 10.

[0074] Therefore, the amount of light that is emitted from the LED elements 10a of the light source unit 10, reflected by the second main surface W1a of the substrate W1 to be processed, and then returned to the LED elements 10a is reduced, thereby preventing the LED elements 10a mounted on the light source unit 10 from being heated by the light reflected by the second main surface W1a of the substrate W1 to be processed.

[0075] The angle θ of the light heating device 1 is confirmed by measuring the inclination of the second main surface W1a of the substrate W1 to be processed and the inclination of the first main surface 10p of the LED substrate 10b using a level and comparing the two. The angle θ of the light heating device 1 can also be calculated by measuring the distance from the first LED element 10a1 to the second main surface W1a of the substrate W1 to be processed, the distance from the second LED element 10a2 to the second main surface W1a of the substrate W1 to be processed, and the distance from the first LED element 10a1 to the second LED element 10a2.

[0076] [Another embodiment] Another embodiment will be described below.

[0077] <1> Fig. 6 is a schematic cross-sectional view of another embodiment of the light heating device 1 when viewed in the Y direction. As shown in Fig. 6, the other embodiment of the light heating device 1 includes a control unit 60 and a drive mechanism 11c that is an angle adjustment mechanism that changes the position of the LED substrate 10b based on a drive signal d2 output from the control unit 60. The control unit 60 in this embodiment includes an input unit 60a, a memory unit 60b, a determination unit 60c, and an output unit 60d.

[0078] The input unit 60a accepts input of data d1 including information on the values ​​of the separation distances D1 and D2. The memory unit 60b stores a table of values ​​of the angle θ that satisfy the above formula (1) corresponding to combinations of the separation distances D1 and D2. The determination unit 60c determines the value of the angle θ based on the values ​​of the separation distances (D1, D2) input to the input unit 60a and the table stored in the memory unit 60b. The output unit 60d outputs a drive signal d2 to the drive mechanism 11c so that the angle θ between the first main surface 10p of the LED substrate 10b and the second main surface W1a of the target substrate W1 becomes the value of the angle θ determined by the determination unit 60c.

[0079] With the above configuration, the control unit 60 of the optical heating device 1 determines the angle θ that satisfies the condition of the above equation (1) based on the predetermined values ​​of the separation distance D1 and separation distance D2, and automatically adjusts the position of the LED substrate 10b to the optimal position.

[0080] <2> The light heating device 1 may be provided with an angle sensor for measuring the angle θ formed between the first main surface 10p and the second main surface W1a. By providing such an angle sensor, the light heating device 1 can adjust the arrangement position of the light source unit 10 while checking whether the arrangement position of the light source unit 10 satisfies the condition of the above formula (1).

[0081] Furthermore, the optical heating device 1 of this embodiment can be configured to detect a state in which the condition of the above equation (1) is no longer satisfied, for example, when the position of the light source unit 10 is displaced due to a large impact, and issue an alert.

[0082] As the angle sensor of the light heating device 1 of this embodiment, for example, a rotary potentiometer or a rotary encoder can be used.

[0083] <3> The configuration of the light heating device 1 described above is merely an example, and the present invention is not limited to the illustrated configurations. [Explanation of symbols]

[0084] 1 : Optical heating device 2: Chamber 2a: Translucent window 3: Support member 3a: Pedestal 3b: Protrusion 3c: Laura 10: Light source unit 10a: LED element 10a1: First LED element 10a2: Second LED element 10b: LED board 10p: First principal surface 11: Frame 11a: Adjustment screw 11b: Support wall 11c: Drive mechanism 60: Control section 60a: Input section 60b: Storage section 60c: Judgment section 60d: Output section L1 : Chief ray W1: Substrate to be processed W1a: Second principal surface

Claims

1. An optical heating device that heats a substrate to be processed by irradiating it with light, a support member on which the substrate to be processed is placed; a plurality of light source units including an LED substrate on which a group of LED elements is mounted; a first main surface of the LED substrate and a second main surface of the substrate to be processed placed on the support member are non-parallel to each other; an optical heating device characterized in that each of the plurality of light source units is arranged to satisfy the following formula (1): when the angle formed by the first main surface and the second main surface is θ, the distance between the first LED element mounted on the LED substrate and located closest to the second main surface in the normal direction to the second main surface is D1, and the distance between the first LED element mounted on the LED substrate and located farthest from the second main surface in the normal direction is D2. 2tan2θ / cosθ≧D2 / D1 (1)

2. The light heating device according to claim 1 , further comprising an angle adjustment mechanism for adjusting the angle θ by changing the position of the LED substrate.

3. The optical heating device according to claim 2, further comprising a control unit that determines the value of the angle θ based on the separation distance D1 and the separation distance D2, and drives the angle adjustment mechanism based on the determined value of the angle θ.

4. 3. The light heating device according to claim 1, further comprising an angle sensor for measuring an angle θ formed between the first main surface and the second main surface.

5. The optical heating device according to claim 1 or 2, characterized in that the support member is provided with a rotation mechanism that rotates the substrate to be processed about an axis that is perpendicular to the second main surface and passes through the center of the second main surface.

6. A heat treatment method for heating a substrate to be treated placed on a support member by irradiating the substrate with light emitted from a plurality of light source units, each of which includes an LED substrate on which an LED element group is mounted, the method comprising: a first main surface of the LED substrate and a second main surface of the substrate to be processed placed on the support member are non-parallel to each other; a heat treatment method comprising: irradiating the substrate to be treated with light emitted from each of the plurality of light source units arranged to satisfy the following formula (1): where θ is the angle formed between the first main surface and the second main surface, D1 is the distance between the substrate to be treated and a first LED element mounted on the LED substrate and located closest to the second main surface in a normal direction to the second main surface, and D2 is the distance between the first LED element and a second LED element mounted on the LED substrate and located farthest from the second main surface in the normal direction. 2tan2θ / cosθ≧D2 / D1 (1)

7. The heat treatment method according to claim 6, wherein the value of the angle θ is determined based on the separation distance D1 and the separation distance D2, and the position of the LED substrate is changed based on the determined value of the angle θ.

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