JP7750154B2 - Light heating device and heat treatment method - Google Patents

Description

The present invention relates to a light heating device and a heat treatment method.

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 processes often use heat treatment methods that use light irradiation, which allows for contactless processing.

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 substrate with heating light (hereinafter sometimes referred to as "heating light"). For example, Patent Document 1 listed below describes a heating device equipped with multiple LEDs.

Japanese Patent Application Laid-Open No. 2020-009927

In recent years, technological advances such as miniaturization in semiconductor manufacturing processes have led to a demand for heating devices that can perform more uniform heat treatment. The inventors of this study conducted extensive research into heating devices that can heat-treat substrates with a more uniform temperature distribution, and discovered the following problems.

In heating devices equipped with multiple solid-state light sources such as LEDs as light sources for emitting heating light, such as the heating device described in Patent Document 1, the multiple solid-state light sources have traditionally been arranged on a plane parallel to the main surface of the substrate to be processed placed on a support member. This type of configuration is generally adopted because, by aligning the distance between the main surface of the substrate to be processed and each solid-state light source, it is easier to predict and examine the illuminance distribution on the main surface of the substrate to be processed, and it is also easier to control the illuminance distribution on the main surface of the substrate to be processed.

However, once multiple solid-state light sources are fixed by soldering or other means to the main surface of the substrate on which they are mounted, it is difficult to change their position thereafter. Therefore, in conventional heating devices that are designed to mount multiple solid-state light sources on a plane parallel to the main surface of the substrate to be processed, which is placed on a support member, fine-tuning the illuminance distribution on the main surface of the substrate to be processed typically requires translating the substrate to which the solid-state light sources are fixed.

However, parallel translation of the substrate to which the solid-state light sources are fixed does not change the arrangement of the multiple solid-state light sources. As a result, the arrangement of the solid-state light sources may not be suitable at the destination of the substrate. Furthermore, when translating the solid-state light sources in a direction perpendicular to the main surface of the substrate to be processed, if the solid-state light sources and the substrate to be processed are brought too close together, the light emitted from the solid-state light sources will be irradiated onto the substrate to be processed before it has had a chance to fully spread, resulting in uneven illumination.

Furthermore, if the solid-state light source is placed too far away from the substrate to be processed, the illuminance will be insufficient and the light will not be able to be irradiated with sufficient illuminance. In other words, with conventional heating devices, it was difficult to fine-tune the illuminance distribution of the light irradiated onto the substrate to be processed according to each substrate.

In view of the above-mentioned problems, the present invention aims to provide an optical heating device and a heat treatment method that enable more precise adjustment of the illuminance distribution on the main surface of a substrate to be treated.

The light heating device of the present invention is
An optical heating device that heats a substrate to be processed by irradiating it with light,
a support member for supporting the substrate to be processed;
a plurality of light source units including an LED substrate on which a group of LED elements is mounted on a first main surface;
When the substrate to be processed is supported on the support member, the angle between the first main surface and the second main surface of the substrate to be processed is θ, the distance between the substrate to be processed 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 substrate to be processed and a second LED element mounted on the LED substrate and located farthest from the second main surface in the normal direction is D2. The arrangement is characterized in that at least one of the light source units is arranged to satisfy the following formula (1):

2tan2θ/cosθ≧D2/D1 (1)

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. Furthermore, the center of the light-emitting surface of the LED element may be defined as the center of the inscribed circle on the outer edge of the area occupied by the LED element when viewing the first principal surface of the LED substrate from the normal direction to the first principal surface.

The angle θ between the first main surface of the LED substrate and the second main surface of the substrate to be processed supported by the support member can be continuously adjusted by adjusting the position of the LED substrate. Furthermore, when tilting the first main surface of the LED substrate relative to the second main surface of the substrate to be processed, the axis of rotation when rotating the LED substrate and the direction in which the LED substrate is tilted can be arbitrary.

In this specification, the separation distance between the first LED element and the second LED element is defined as the center-to-center distance between the LED elements when viewed from a direction perpendicular to the first main surface of the LED substrate. If a single light source unit contains multiple first LED elements and multiple second LED elements, separation distance D2 corresponds to the shortest separation distance between each combination of first LED elements and second LED elements.

With the above configuration, the optical heating device can continuously adjust the illuminance distribution on the main surface of the substrate to be processed by adjusting the tilt angle θ of the LED substrate and the tilt direction of the LED substrate, in addition to adjusting the arrangement of the LED elements on the first main surface of the LED substrate. In other words, an optical heating device with the above configuration can adjust the illuminance distribution on the second main surface of the substrate to be processed more precisely than conventional configurations.

Furthermore, with the above configuration, the chief ray of light emitted from the LED element mounted in the light source unit, which is positioned at least closer to the second LED element than the first LED element, is reflected by the second main surface of the substrate to be processed and travels outside the area where the LED elements on the LED board of the light source unit are located, or toward the outside of the light source unit.

As a result, 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 processed, and returned to the LED element or its vicinity is reduced. In this way, the LED element mounted in the light source unit is prevented from being heated by light reflected by the second main surface of the substrate to be processed. Note that the "chief ray" refers to the ray of light that exhibits the highest intensity among the light emitted from the light source.

The relationship between the derivation of equation (1) above and the effects of the above configuration will be described in detail in the "Embodiment of the Invention" section, with reference to drawings, etc.

In the above-mentioned light heating device,
The plurality of light source units include:
a first light source unit in which the LED substrate is tilted so that a normal line of the first main surface extending from the light source unit toward the substrate to be processed faces a central portion of the substrate to be processed while the substrate to be processed is supported by the support member;
The device may include a second light source unit in which the LED substrate is tilted so that the normal to the first main surface extending from the light source unit toward the substrate to be processed faces the peripheral edge side of the substrate to be processed.

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.

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.

With the above configuration, the angle θ can be adjusted appropriately depending on the shape of the substrate to be processed and the setting of the separation distance D1 during the heating process of the substrate to be processed.

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

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

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.

With the above configuration, the optical heating device can adjust the position of the light source unit while checking whether the position of the light source unit satisfies the condition of equation (1) above.

Furthermore, with the above configuration, if the optical 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.

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.

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, which is 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.

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.

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

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 transmit or reflect the other part. In other words, according to the graph in Figure 4, when a silicon wafer is irradiated with light with a wavelength of 1100 nm, more than 50% of the irradiated light is transmitted or reflected without being absorbed.

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

Furthermore, silicon wafers have an absorption rate of approximately 10% for light with wavelengths of less than 300 nm, which is significantly lower than the absorption rate for light with wavelengths of around 1000 nm. 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.

By using LED elements mounted in the light source unit that have a peak wavelength within the above wavelength range, the proportion of the light emitted from the light source unit and irradiated onto the substrate being processed that is reflected by the second main surface of the substrate being processed is reduced. This prevents the LED elements mounted in the light source unit from being irradiated with heating light emitted from the LED elements and reflected by the substrate being processed.

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.

As shown in Figure 4, silicon (Si) exhibits little 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.

Therefore, with the above configuration, it is possible to create an optical heating device that is less affected by variations in the peak wavelength of the light emitted by the LED elements during the heating process of silicon wafers.

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 a first main surface of the substrate with light emitted from a plurality of light source units including an LED substrate having an LED element group mounted thereon, the method comprising:
When the substrate to be processed is supported by the support member, the angle between the first main surface and the second main surface of the substrate to be processed is θ, the distance between the substrate to be processed and a first LED element mounted on the LED board that is 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 board that is farthest from the second main surface in the normal direction is D2, the substrate to be processed is irradiated with heating light that includes light emitted from a light source unit that is arranged to satisfy the following formula (1):

2tan2θ/cosθ≧D2/D1 (1)

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 board based on the determined value of the angle θ.

The present invention provides an optical heating device and a heat treatment method that enable more precise adjustment of the illuminance distribution on the main surface of the substrate to be treated.

3 is a schematic cross-sectional view of an embodiment of a light heating device when viewed in the Y direction. FIG. 2 is a view of the frame of FIG. 1 as seen from the −Z side. 2 is a view of the chamber of FIG. 1 as seen from the +Z side. 1 is a graph showing the relationship between the wavelength of light and the absorptance when the temperature of silicon (Si) is 543K. 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. 3 is a schematic cross-sectional view of an embodiment of a light heating device when viewed in the Y direction. FIG. 3 is a schematic cross-sectional view of an embodiment of a light heating device when viewed in the Y direction. FIG. 3 is a schematic cross-sectional view of an embodiment of a light heating device when viewed in the Y direction. FIG. FIG. 10 is a schematic cross-sectional view of another embodiment of the light heating device when viewed in the Y direction.

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

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

In the following description, as shown in Figures 1 and 3, the plane parallel to the second main surface W1a of the substrate W1 to be processed, which is the target of heat treatment and is housed in chamber 2, is referred to as the XY plane, and the direction perpendicular to the XY plane is referred to as the Z direction.

Also, when expressing a direction, if a distinction is made between positive and negative directions, a positive or negative sign is added, such as "+Z direction" and "-Z direction." When expressing a direction without distinguishing between positive and negative directions, it is simply written as "Z direction."

Furthermore, while the explanation of the first embodiment is based on the assumption that the substrate W1 to be processed is a silicon wafer, 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.).

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

As shown in Figures 1 and 3, the support member 3 has a base 3a with multiple protrusions 3b provided on it, and the substrate W1 to be processed is placed and supported on the tips of the multiple protrusions 3b.

As shown in FIG. 1, the support member 3 of this embodiment is provided with a rotation mechanism using multiple rollers 3c and is configured to be freely rotatable. When heat treatment is performed, the rotation of the rollers 3c allows the substrate W1 to be rotated in the XY plane around axis z1, which 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 treated if the light source unit 10 is configured to irradiate light uniformly in the circumferential direction of the second main surface W1a of the substrate W1 to be treated. Furthermore, the support member 3 may be configured to support the substrate W1 to be treated by hooking the peripheral edge of the substrate W1, for example.

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

The LED elements 10a included in the light source unit 10 of this embodiment emit infrared light with a peak wavelength of 850 nm. Each LED element 10a is arranged on the first main surface 10p of the LED substrate 10b. In the example shown in FIG. 1, the light source unit 10 includes a region where the first main surface 10p is parallel to the XY plane and a region where the first main surface 10p is inclined with respect to the XY plane. In the region where the first main surface 10p is parallel to the XY plane, the multiple LED elements 10a are arranged in a direction parallel to the XY plane. Note that the LED elements 10a may also be arranged parallel to each side of the LED substrate 10b. In this case, the multiple LED elements 10a are arranged in the X and Y directions in the region where the first main surface 10p is parallel to the XY plane.

In this embodiment, as shown in FIG. 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. Furthermore, the arrangement of the LED elements 10a on the LED substrate 10b may be adjusted as appropriate depending on the expected temperature distribution during the heat treatment of the substrate W1 to be treated.

Figure 4 is a graph showing the relationship between light wavelength and absorptance when the temperature of silicon (Si) is 543 K. The value of 543 K was selected because it is often around the target temperature when heating a silicon wafer, or is a temperature during heating. The peak wavelength of the light emitted by the LED element 10a can be set arbitrarily, but as shown in Figure 4, in order to ensure an absorptance of at least 25%, i.e., a reflectance of at least 75%, it is preferable that the peak wavelength be between 300 nm and 1000 nm, and more preferably between 350 nm and 950 nm.

Furthermore, as shown in Figure 4, silicon (Si) exhibits a nearly constant absorptance for light with a wavelength in the range of 800 nm to 900 nm, regardless of wavelength. Therefore, from the perspective of suppressing uneven heating, it is more preferable that the light emitted by the LED element 10a mounted in the light source unit 10 has a peak wavelength of 800 nm to 900 nm, and especially preferably 820 nm to 880 nm.

As shown in FIG. 1, the frame 11 in this embodiment is equipped 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 to prevent the light source unit 10 from shifting position when the tilt is adjusted.

As shown in FIG. 1, the frame 11 in this embodiment is adjusted by the adjustment screws 11a so that the first main surface 10p of the LED substrate 10b of the light source unit 10 located toward the center is parallel to the second main surface W1a (XY plane) of the substrate W1 to be processed. Furthermore, the frame 11 is adjusted by the adjustment screws 11a so that the first main surface 10p of the LED substrate 10b of the light source unit 10 located toward the periphery is tilted by an angle θ with respect to the second main surface W1a (XY plane) of the substrate W1 to be processed.

The conditions for angle θ are explained below.

Figure 5 is a schematic diagram illustrating the configuration of the light source unit 10 and the relative positioning of the light source unit 10 and the substrate W1 to be processed. For ease of explanation, the configuration shown in Figure 5 is illustrated with differences from Figure 1 in the angle 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.

5, the first LED element 10a1 is the LED element located closest to the second main surface W1a in the Z direction among the multiple LED elements 10a mounted on the LED substrate 10b. The second LED element 10a2 is the LED element located farthest from the second main surface W1a in the Z direction among the multiple LED elements 10a mounted on the LED substrate 10b. The light source unit 10 is positioned such that the inclination angle θ satisfies the above formula (1) when the separation distance from the substrate W1 is D1 and the separation distance between the second LED element 10a2 and the first LED element 10a1 is D2. For clarity, the above formula (1) is presented again below.

2tan2θ/cosθ≧D2/D1 (1)

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.

The process for deriving equation (1) above will be explained below. Note that the following explanation assumes that the chief ray L1 is specularly reflected without being absorbed by the second main surface W1a of the substrate W1 to be processed.

First, as shown in Figure 5, let P1 be the point where the chief ray L1 of light emitted from the first LED element 10a1, after being reflected by the second main surface W1a of the substrate to be processed W1, intersects with the plane A1 obtained by extending the light emission surface 10c of the LED element 10a. Let R be the distance between the center of the light emission surface 10c of the first LED element 10a1 and point P1 in a direction parallel to the main surface of the LED substrate 10b, and let E be the distance between the center of the light emission surface 10c and point P1 in the Z direction. Furthermore, let B be the distance between the first LED element 10a1 and the second LED element 10a2 in the Z direction.

As shown in Figure 5, the chief ray L1 of light emitted from the first LED element 10a1 travels toward the substrate W1 (-Z side) and then reaches the second main surface W1a. Here, the distance traveled by the chief ray L1 from when it is emitted from the first LED element 10a1 until it reaches the second main surface W1a of the substrate W1 is defined as S.

Principal ray L1 is incident on the second principal surface W1a at an incident angle θ and is reflected at a reflection angle θ. Principal ray L1 then travels toward the light source unit 10 (+Z side) and eventually reaches point P1.

Regarding the traveling distance S of the chief ray L1, the chief ray L1 emitted from the first LED element 10a1 has the shortest traveling distance. The closer the LED element 10a is to the second LED element 10a2, the longer the traveling distance of the chief ray L1 emitted from the LED element 10a. 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 by the light emitted from the LED element 10a, reflected by the second main surface W1a, and reaching surface A1.

Based on the above relationship, if point P1, the arrival point of chief ray L1, is closer to the second LED element 10a2 than midpoint C1 between the first LED element 10a1 and the second LED element 10a2, then, as described above, chief ray L1 of light emitted from the LED element 10a closer to the second LED element 10a2 will reach at least the area of the LED substrate 10b where no LED element 10a is located. In other words, more than half of the light emitted from the LED element 10a and reflected from the second principal surface W1a toward the LED substrate 10b can be reflected outside the LED substrate 10b, and as a result, the LED element 10a is prevented from being heated by the light reflected from the second principal surface W1a.

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 expressed by the following formula (2).

2E≧B (2)

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

2R≧D2 (3)

5, the relationship between the distance R, the travel distance S, and the angle θ is expressed as R=S×tan 2θ. When this relational expression is substituted into the above equation (3), the following equation (4) is obtained.

2(S × tan2θ) ≧ D2 (4)

Finally, as shown in Figure 5, the relationship between the travel distance S, the separation distance D1, and the angle θ is expressed as S = D1/cos θ. Therefore, when this relationship is substituted into equation (4) and rearranged, it becomes equation (1) above.

With the above configuration, the chief ray L1 of light emitted from the LED elements 10a mounted on the light source unit 10, which are positioned 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 travel outside the area where the LED elements 10a are located on the LED substrate 10b of the light source unit 10, or toward the outside of the light source unit 10.

As a result, 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. This prevents the LED elements 10a mounted on the light source unit 10 from being heated by light reflected by the second main surface W1a of the substrate W1 to be processed.

The angle θ of the optical heating device 1 is calculated 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 spirit level and comparing the two. The angle θ of the optical 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.

In this embodiment, the frame 11 is equipped with an adjustment screw 11a and a support wall 11b as shown in FIG. 1, but it may also be configured to fix the light source unit 10 at a predetermined angle θ without the adjustment screw 11a and support wall 11b. Furthermore, the angle adjustment mechanism may be, for example, a piezoelectric actuator or a micrometer head with an encoder.

Figures 6 to 8 are schematic cross-sectional views of an embodiment of the light heating device 1 different from that shown in Figure 1, viewed in the Y direction. As shown in Figures 6 to 8, the frame 11 in this embodiment may be configured to fix the light source unit 10 at a predetermined angle θ without including the adjustment screw 11a and support wall 11b.

In the embodiments described with reference to Figures 1 and 6, the light source unit 10 is tilted so that the normal n1 to the first main surface 10p points toward the center of the substrate W1 to be processed when it is placed on the support member 3. However, as shown in Figure 7, the light source unit 10 may also be tilted so that the normal n1 points toward the peripheral edge of the substrate W1 to be processed.

Furthermore, as shown in FIG. 8, the optical heating device 1 may include a mixture of light source units 10 (first light source units) inclined so that the normal n1 points toward the center of the substrate W1 to be processed, and light source units 10 (second light source units) inclined so that the normal n2 points toward the peripheral edge of the substrate W1 to be processed. The configuration of the optical heating device 1 shown in FIG. 8 allows for concentrated irradiation of light toward the peripheral edge of the substrate W1 to be processed, which is prone to heat dissipation, thereby suppressing uneven heating across the entire substrate W1 to be processed.

In the configuration shown in Figure 8, the light source units 10 arranged on the central side of the frame 11 are adjusted to have fewer LED elements 10a than the light source units 10 arranged on the peripheral edge side. This is because the central side of the substrate W1 to be processed dissipates less heat than the peripheral edge side, and the light intensity required for heat treatment is relatively low.

[Another embodiment]
Another embodiment will be described below.

<1> Figure 9 is a schematic cross-sectional view of another embodiment of the light heating device 1 when viewed in the Y direction. As shown in Figure 9, this embodiment of the light heating device 1 includes a control unit 60 and a drive mechanism 11c, which 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.

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 angle θ that satisfy equation (1) above and correspond to combinations of separation distances D1 and D2. The determination unit 60c determines the value of angle θ based on the values of each separation distance (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 substrate to be processed W1 becomes the value of angle θ determined by the determination unit 60c.

With the above configuration, the control unit 60 of the optical heating device 1 determines the angle θ that satisfies the condition of equation (1) above 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.

In each of the above-described embodiments, the light source units 10 are arranged so that the first main surface 10p of the LED substrate 10b is parallel to the second main surface W1a of the substrate W1 to be processed. However, as shown in FIG. 9, in all light source units 10, the first main surface 10p of the LED substrate 10b may be tilted relative to the second main surface W1a of the substrate W1 to be processed. Furthermore, the optical heating device 1 may be additionally provided with optical systems such as collimating lenses and condensing lenses corresponding to each LED element 10a in order to more efficiently heat the peripheral edge side of the substrate W1 to be processed.

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

Furthermore, the optical heating device 1 of this embodiment can be configured to detect a state in which the condition of the above formula (1) is no longer satisfied, such as when the position of the light source unit 10 shifts due to a large impact, and issue an alert.

In addition, the angle sensor for the light heating device 1 of this embodiment may be, for example, a rotary potentiometer or a rotary encoder.

〈3〉 The configuration of the light heating device 1 described above is merely an example, and the present invention is not limited to the configurations shown in the drawings.

REFERENCE SIGNS LIST 1: Light heating device 2: Chamber 2a: Light-transmitting window 3: Support member 3a: Base 3b: Protrusion 3c: Roller 10: Light source unit 10a: LED element 10a1: First LED element 10a2: Second LED element 10b: LED substrate 10c: Light emission surface 10p: First main surface 11: Frame 11a: Adjustment screw 11b: Support wall 11c: Drive mechanism 60: Control unit 60a: Input unit 60b: Memory unit 60c: Determination unit 60d: Output unit L1: Chief ray W1: Substrate to be processed W1a: Second main surface

Claims (8)

An optical heating device that heats a substrate to be processed by irradiating it with light,
a support member for supporting the substrate to be processed;
a plurality of light source units including an LED substrate on which a group of LED elements is mounted on a first main surface;
When the substrate to be processed is supported on the support member, the angle between the first main surface and the second main surface of the substrate to be processed is θ (0°<θ<45°) , the distance between the substrate to be processed and a first LED element mounted on the LED board that is closest to the second main surface in the normal direction to the second main surface is D1, and the distance between the substrate to be processed and a second LED element mounted on the LED board that is farthest from the second main surface in the normal direction is D2, and at least one of the light source units is arranged to satisfy the following formula (1):

2tan2θ/cosθ≧D2/D1 (1)
The plurality of light source units include:
a first light source unit in which the LED substrate is tilted so that a normal line of the first main surface extending from the light source unit toward the substrate to be processed faces a central portion of the substrate to be processed while the substrate to be processed is supported by the support member;
The optical heating device described in claim 1, characterized in that it includes a second light source unit in which the LED substrate is tilted so that the normal of the first main surface from the light source unit toward the substrate to be processed faces the peripheral edge side of the substrate to be processed. The optical heating device described in claim 1 is characterized in that it is equipped with an angle adjustment mechanism that adjusts the angle θ by changing the position of the LED substrate. The optical heating device of claim 3 further comprises 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. The optical heating device described in claim 1, characterized in that it is equipped with an angle sensor for measuring the angle θ formed between the first main surface and the second main surface. The optical heating device described in claim 1, characterized in that the support member is equipped 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. A heat treatment method for heating a substrate to be treated placed on a support member by irradiating a first main surface of the substrate with light emitted from a plurality of light source units including an LED substrate having an LED element group mounted thereon, the method comprising:
a heat treatment method comprising: irradiating the substrate to be treated with heating light including light emitted from a light source unit arranged to satisfy the following formula (1): when the angle between the first main surface and the second main surface of the substrate to be treated is θ (0°<θ<45°) , the distance between the substrate to be treated and a first LED element mounted on the LED board that is closest to the second main surface in a normal direction to the second main surface is D1, and the distance between the substrate to be treated and a second LED element mounted on the LED board that is farthest from the second main surface in a normal direction to the second main surface is D2.

2tan2θ/cosθ≧D2/D1 (1)
The heat treatment method according to claim 7, characterized in that 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.