Light source unit and optical heating device

Abstract

The present invention provides a light source unit and a light heating device that can raise the temperature of a semiconductor substrate while suppressing the shortening of the lifespan of LED elements compared to conventional methods. [Solution] A light source unit for heat treatment of a semiconductor substrate, comprising: a plurality of LED elements emitting light in a first direction; an LED substrate on which the plurality of LED elements are arranged; a lens substrate positioned opposite the plurality of LED elements on the LED substrate with respect to the first direction; and a plurality of lens elements formed on the lens substrate in a convex shape at positions corresponding to each LED element, wherein the LED density obtained by dividing the substantial number of LED elements located within a first region formed by virtually connecting the centers of the plurality of adjacent LED elements facing the lens substrate when viewed in the first direction by the area of ​​the first region is 5 LEDs / cm² 2 More than 15 pieces / cm 2 The following is a characteristic feature: the ratio of the length of the lens element to the length of the LED element is 8.0 or less.

Description

[Technical Field] 【0001】 The present invention relates to a light source unit for heating a semiconductor substrate by irradiating the substrate with heating light, and to a light heating device equipped with the light source unit. [Background technology] 【0002】 In semiconductor manufacturing processes, various treatments such as film deposition, oxidation diffusion, modification, and annealing are performed on semiconductor substrates such as silicon wafers. In these treatments, heating methods that involve irradiating the main surface of the semiconductor substrate with heating light (hereinafter referred to as "heating light" for convenience) are frequently employed because they allow for non-contact processing. Here, "main surface" refers to the surface of a plate-like object that has a much larger area than the other surfaces. 【0003】 Examples of heating light sources include halogen lamps and LED elements. Of these, LED elements are increasingly being adopted because they enable rapid heating of the semiconductor substrate being heated. 【0004】 The light output of a single LED element is typically smaller than that of, for example, a halogen lamp. Therefore, in order to irradiate the semiconductor substrate with the heating light necessary for processing, multiple LED elements are arranged facing the semiconductor substrate, as shown in Patent Document 1 below. [Prior art documents] [Patent Documents] 【0005】 [Patent Document 1] Special Publication No. 2018-525813 [Overview of the project] [Problems that the invention aims to solve] 【0006】 By using LED elements as the light source for heating, it becomes possible to rapidly heat up semiconductor substrates. However, in recent years, there has been a growing demand to heat semiconductor substrates at even higher temperatures while still achieving rapid heating. 【0007】 In light of the above requirements, it is conceivable to mount more LED elements in the light source unit of the optical heating device in order to irradiate the semiconductor substrate with more heating light. Specifically, it is conceivable to reduce the distance between individual LED elements and add more LED elements. However, LED elements have the property that their lifespan is shortened when the temperature of the LED element itself rises. Therefore, if more LED elements are mounted and the distance between individual LED elements is reduced, the temperature of the LED elements themselves will rise more easily, resulting in a shorter lifespan for the LED elements. 【0008】 In other words, if a configuration is adopted in which the distance between adjacent LED elements is reduced and additional LED elements are added in order to increase the heating temperature of the semiconductor substrate, the lifespan of the LED elements will be shortened. 【0009】 A shorter lifespan for LED elements means a shorter replacement cycle for LED elements. Even if the temperature of the semiconductor substrate can be increased, if LED elements need to be replaced in a short period of time, it is not practical as a light source unit for heating the semiconductor substrate. 【0010】 In view of the above circumstances, the present invention aims to provide a light source unit and a light heating device that can raise the temperature of a semiconductor substrate while suppressing the shortening of the lifespan of LED elements compared to conventional methods. [Means for solving the problem] 【0011】 The light source unit according to the present invention is A light source unit that irradiates a semiconductor substrate with light to perform a heating treatment on the semiconductor substrate, Multiple LED elements that emit the aforementioned light in the first direction, An LED substrate on which multiple LED elements are arranged, A lens substrate is arranged opposite to a plurality of LED elements on the LED substrate with respect to the first direction, The lens substrate comprises a plurality of lens elements formed in a convex shape at positions corresponding to each of the LED elements, which reduce the divergence angle of the light emitted by the LED elements, When viewed in the first direction, the LED density obtained by dividing the substantial number of LED elements located within the first region, which is formed by virtually connecting the centers of a plurality of adjacent LED elements facing the lens substrate, by the area of ​​the first region, is 5 LEDs / cm². 2 More than 15 pieces / cm 2 The following: With respect to the direction parallel to the plane perpendicular to the first direction, the ratio obtained by dividing the length of the LED element by the length of the lens element corresponding to the LED element is 8.0 or less. 【0012】 One possible method for increasing the temperature of a semiconductor substrate by irradiating it with a large amount of heating light is to reduce the spacing between LED elements that emit heating light and to add more LED elements. However, this method tends to cause the temperature of the LED elements to rise easily, leading to a shortened lifespan of the LED elements. In response to this, the inventors considered arranging lens elements in conjunction with the LED elements to irradiate the semiconductor substrate with more heating light and increase the temperature of the semiconductor substrate. Here, they realized that when arranging multiple lens elements in an array corresponding to multiple LED elements, it is necessary to consider the interference of adjacent lens elements. After diligent research, the inventors found that with the above configuration, it is possible to irradiate the semiconductor substrate with more heating light and increase the temperature of the semiconductor substrate while suppressing the shortening of the lifespan of the LED elements, compared to the conventional configuration without lens elements. Further details will be described later in the section on "Modes for Carrying Out the Invention." 【0013】 The above light source unit is The LED substrate is provided with a support member that is arranged on the LED substrate, extends beyond the LED element in the first direction, and supports the lens substrate, The lens substrate may be fixed to the support member via an adhesive. 【0014】 With the above configuration, the lens substrate can be easily positioned relative to each LED element by fixing it to the support member. Considering that the area around the LED element becomes hot when the LED element is lit, it is preferable that the adhesive used to bond the lens substrate and the support member has high heat resistance. A suitable adhesive is a ceramic-based adhesive. 【0015】 In the above light source unit, The lens element may have a convex shape on the opposite side from the LED element. 【0016】 From the viewpoint of facilitating the incidence of heating light emitted by the LED element onto the corresponding lens element, it is preferable that the distance between the LED substrate and the lens substrate be small. However, with the above configuration, even when the distance between the LED substrate and the lens substrate is small, the lens element can be easily formed, which is preferable. For example, the distance between the LED substrate and the lens substrate is preferably 2 mm or less, and more preferably 1 mm or less. 【0017】 Furthermore, the above light source unit is The system has multiple heating groups in which multiple LED elements are arranged in close proximity to each other. In at least one of the heating groups, the LED density is 5 LEDs / cm². 2 More than 15 pieces / cm 2 The following applies, and the ratio may be 8.0 or less. 【0018】 In the above light source unit, The LED element may be positioned facing the peripheral edge of the semiconductor substrate. 【0019】 On the main surface of a semiconductor substrate, the peripheral edges dissipate heat more easily than the central part. Therefore, when heating a semiconductor substrate, it is preferable to irradiate the peripheral edges with more heating light than the central part to compensate for the heat dissipation at the peripheral edges. Furthermore, LED elements facing the peripheral edges of a semiconductor substrate tend to emit a portion of their heating light in a direction different from that of the semiconductor substrate compared to LED elements facing the central part. In contrast, the above configuration makes it easier to irradiate the semiconductor substrate with the heating light emitted by the LED elements facing the peripheral edges, which is preferable. 【0020】 The term "peripheral edge of the semiconductor substrate" may also be defined as the region on the main surface of the semiconductor substrate where the distance from the edge is 30% or less of the diameter of the main surface. Furthermore, the term "central part of the semiconductor substrate" refers to the region within the main surface of the semiconductor substrate that lies inside the peripheral edge. [Effects of the Invention] 【0021】 According to the present invention, a light source unit and a light heating device are provided that can raise the temperature of a semiconductor substrate while suppressing the shortening of the lifespan of LED elements compared to conventional methods. [Brief explanation of the drawing] 【0022】 [Figure 1] This is a side cross-sectional view showing an example of the configuration of a light heating device. [Figure 2] This is a plan view of the light source unit shown in Figure 1, as seen in the Z direction. [Figure 3] This is a diagram showing an enlarged portion of Figure 2. [Figure 4] This is a diagram showing a magnified view of the area surrounding the LED element and lens substrate. [Figure 5A] Figure 5A is a diagram showing a further enlargement of Figure 4. [Figure 5B] Figure 5B is a view of Figure 5A in the Z direction. [Figure 6] This is a perspective view showing an alternative configuration of the lens element. [Figure 7] This diagram shows the simulation conditions in Verification 1. [Figure 8]Figure 7 shows the lens substrate as viewed in the Z direction. [Figure 9] This graph shows the results of Verification 1. [Figure 10] This graph shows the relationship between the temperature reached by an LED and the lifespan of the LED. [Figure 11] This graph shows the results of Verification 3. [Figure 12] This diagram shows a modified version of the light source unit, following Figure 2. [Figure 13] This is a diagram showing an enlarged portion of Figure 12. [Figure 14] Figure 14 is a diagram showing another modified example of the light source unit 10, following the example in Figure 2. [Modes for carrying out the invention] 【0023】 [First Embodiment] The embodiments of the optical heating device and light source unit according to the present invention will be described below with reference to the drawings. Note that the following drawings are schematic illustrations, and the dimensional ratios and numbers shown in the drawings do not necessarily correspond to the actual dimensional ratios and numbers. 【0024】 Figure 1 is a side cross-sectional view showing an example of the configuration of a photothermal heating device according to the present invention. The photothermal heating device 1 heats the semiconductor substrate W1 by irradiating the semiconductor substrate W1 with heating light. As shown in Figure 1, the photothermal heating device 1 comprises a light source unit 10 that irradiates the semiconductor substrate W1 with heating light, a chamber 11 that houses the semiconductor substrate W1, and a support unit 12 that supports the semiconductor substrate W1. 【0025】 In the following description, the XYZ coordinate system, in which the normal direction of the main surface W1a of the semiconductor substrate W1 is defined as the Z direction and the plane perpendicular to the Z direction is defined as the XY plane, will be referred to as appropriate. When expressing a direction, if positive and negative directions are distinguished, they will be indicated with a sign, such as "+X direction" and "-X direction". When expressing a direction without distinguishing between positive and negative directions, it will simply be described as "X direction". In other words, in this specification, when simply described as "X direction", both "+X direction" and "-X direction" are included. The same applies to the Y direction and Z direction. 【0026】 As shown in Figure 1, the chamber 11 includes a support unit 12 inside that supports the semiconductor substrate W1. For example, the support unit 12 is configured to support the semiconductor substrate W1 by the negative pressure formed by an intake mechanism (not shown). The configuration of the support unit 12 is arbitrary as long as it can support the semiconductor substrate W1 with its main surface W1a parallel to the XY plane. For example, the support unit 12 may have a plurality of pin-shaped protrusions that support the semiconductor substrate W1. Alternatively, the support unit 12 may be configured to allow the semiconductor substrate W1 to rotate around an axis normal to the center of the semiconductor substrate W1. 【0027】 In this embodiment, the semiconductor substrate W1 is a semiconductor wafer such as a silicon substrate. The diameter of the main surface W1a of the semiconductor substrate W1 is arbitrary, but as an example, the diameter is 300 mm. 【0028】 Figure 2 is a plan view of the light source unit 10 shown in Figure 1, viewed in the Z direction. In Figure 2, the position of the semiconductor substrate W1 is schematically indicated by a dashed line. Figure 3 is an enlarged view of a part of Figure 2. As shown in Figures 2 and 3, the light source unit 10 includes a plurality of LED elements 3, 3, ..., an LED substrate 5 on which the plurality of LED elements 3 are arranged, a lens substrate 7 facing the LED substrate 5 in the Z direction, a lens element 9 formed on the lens substrate 7, and a heat sink 15 supporting the LED substrate 5. In Figure 3, the lens substrate 7 and the lens element 9 are transparent and indicated by dashed lines. 【0029】 The LED substrate 5 is made of a ceramic material such as aluminum nitride or silicon nitride, and is arranged to extend in the XY plane. The main surface of the LED substrate 5 on the -Z side faces the main surface W1a of the semiconductor substrate W1. As an example, the LED substrate 5 is placed on a heat sink 15 and supported by the heat sink 15, as shown in Figure 1. The heat sink 15 is made of a metallic material such as copper, stainless steel, or aluminum. 【0030】 In this embodiment, the light source unit 10 has multiple LED substrates 5, as shown in Figure 2. However, this is optional, and the light source unit 10 may have only one LED substrate 5. 【0031】 As shown in Figure 1, the multiple LED elements 3 emit heating light L1 in the -Z direction. The Z direction corresponds to the "first direction". Also, as shown in Figure 3, the multiple LED elements 3 are arranged in a planar manner on the main surface of the LED substrate 5. The LED elements 3 are, for example, isotropic and exhibit a 1mm x 1mm square shape when viewed in the Z direction. Typically, the length of the LED element 3 in the X direction is 0.5mm to 2mm, and the length in the Y direction is 0.5mm to 2mm. Alternatively, the LED element 3 may exhibit a circular shape with a diameter of 1mm when viewed in the Z direction. If the LED element 3 exhibits a circular shape, its diameter is, for example, 0.5mm to 2mm. 【0032】 In this embodiment, the multiple LED elements 3 are arranged on the LED substrate 5 to form multiple heating groups G1, as shown in Figure 3. For example, a heating group G1 consists of multiple LED elements 3 arranged to overlap with one lens substrate 7 when viewed in the Z direction (see Figure 3). In this embodiment, for example, the LED substrate 5 located on the -X side has eight heating groups G1. 【0033】 Furthermore, within the heating group G1, multiple LED elements 3 may be arranged in close proximity to each other. Here, "arranged in close proximity" means that the distance between the centers of the LED elements 3 (see also Figure 5B described later) is 5 times or less the length of the LED element 3, preferably 3 times or less. Note that a single lens substrate 7 may be placed over multiple heating groups G1 in which multiple LED elements 3 are arranged in close proximity to each other. 【0034】 For example, the heating light L1 emitted by the LED element 3 is said to have a peak wavelength in the range of 350 nm to 450 nm. 【0035】 As shown in Figures 1 and 3, the lens substrate 7 is positioned on the -Z side of the LED substrate 5, facing the LED substrate 5 in the Z direction. Also, as shown in Figure 3, the lens substrate 7 is positioned so as to overlap with the multiple LED elements 3 when viewed in the Z direction, and faces the multiple LED elements 3. Note that the light source unit 10 may also have an LED substrate 5 without the lens substrate 7, as shown in Figure 3. Furthermore, it is optional whether all LED elements 3 on the LED substrate 5 face the lens substrate 7. In other words, as shown in Figure 3, the LED substrate 5 may have both LED elements 3 with the lens substrate 7 facing it and LED elements 3 without the lens substrate 7 facing it. Hereafter, to distinguish between the two, the LED elements with the lens substrate 7 facing it will be referred to as "LED element 3," and the LED elements without the lens substrate 7 facing it will be referred to as "LED element 13." 【0036】 The lens substrate 7 is made of a glass material such as quartz glass, and transmits the heating light L1 emitted by the LED element 3. Here, "transmits heating light" may be interpreted as having a light transmittance of 80% or more for the heating light L1. 【0037】 Figure 4 is a magnified view of the area surrounding the LED element 3 and the lens substrate 7. As shown in Figure 4, multiple lens elements 9 are formed on the main surface of the lens substrate 7 on the -Z side. Each lens element 9 is formed corresponding to each LED element 3 (see also Figure 5B, described later). In other words, the lens substrate 7 has a group of lens elements consisting of multiple lens elements 9, corresponding to the heating group G1. In this embodiment, the lens elements 9 have a convex shape on the -Z side. More specifically, the lens element 9 is a convex lens having a spherical surface formed from a revolving body shape with a central axis passing through the Z direction. However, the lens element 9 is not limited to being a convex lens having a spherical surface. For example, the lens element 9 may be an aspherical lens. 【0038】 The curvature of the lens element 9 can be determined, for example, by simulation with fixed lengths a1 of the LED element 3 and b1 of the lens element 9 (see Figure 5A described later). Specifically, when LED elements are arranged on a semiconductor substrate with a diameter of 20 mm at a distance of 80 mm, and the curvature of the lens element corresponding to the LED element is varied, the curvature of the lens element that maximizes light reception can be adopted. Note that these simulation conditions are merely an example. Furthermore, assuming that the light reception rate is 100% when all light rays output from the LED element are received, the curvature of the lens element may be adopted within a range where the light reception rate is 80% or higher, or within a range where the light reception rate is 50% or higher, taking into consideration, for example, the processing accuracy. 【0039】 As an example, the length b1 of the lens element 9 (see Figure 5A described later) is 3 mm to 8 mm, preferably 4 mm to 6 mm. 【0040】 Figure 4 schematically shows the propagation of heating light L1 emitted by the LED element 3. As shown in Figure 4, the heating light L1 emitted by the LED element 3 has a divergence angle and propagates while diverging. Here, the lens element 9 reduces the divergence angle of the incident heating light L1 before it is emitted. This allows the heating light L1 emitted from the LED element 3 and directed in a direction different from the semiconductor substrate W1 to be directed towards the heating light L1. In other words, by positioning the lens element 9 opposite the LED element 3, a large amount of heating light L1 can be irradiated onto the semiconductor substrate W1. 【0041】 In particular, in the case of an LED element 3 positioned in a region facing the peripheral edge of the semiconductor substrate W1, a portion of the heating light L1 tends to propagate in a direction different from that of the semiconductor substrate W1. In view of this, as shown in this embodiment, it is preferable to position the lens substrate 7 relative to the LED element 3 positioned in a region facing the peripheral edge of the semiconductor substrate W1 (see Figures 1 and 2). Here, "peripheral edge of the semiconductor substrate W1" may refer to a region on the main surface W1a of the semiconductor substrate W1 where the distance from the edge is 30% or less of the diameter of the main surface W1a. 【0042】 Figure 5A is a further enlarged view of Figure 4, and Figure 5B is a view of Figure 5A in the Z direction. As shown in Figures 5A and 5B, in this embodiment, the vertex 9a of the lens element 9 and the center 3a of the LED element 3 are arranged to coincide when viewed in the Z direction. Here, the coincidence of the vertex 9a of the lens element 9 and the center 3a of the LED element 3 means that the deviation between the optical axis of the LED element 3 and the central axis of the lens element 9 is 10% or less of the length a1 of the LED element 3, and more preferably 5% or less. Note that while Figure 5A shows the length a1 in the X direction, a similar discussion is possible for the Y direction. 【0043】 It is preferable that the lens element 9 is formed to correspond to all LED elements 3 facing a single lens substrate 7, as shown in Figure 5B. 【0044】 Furthermore, as shown in Figure 5A, the lens substrate 7 is fixed to a support member 20 placed on the LED substrate 5. For example, the lens substrate 7 and the support member 20 are bonded together with an adhesive 21. 【0045】 The support member 20 is preferably made of an insulating material. Examples of insulating materials include ceramic materials such as aluminum nitride and glass materials such as quartz glass. As an example, the support member 20 is made of a plate made of aluminum nitride. As shown in Figure 4, the support member 20 extends from the LED substrate 5 beyond the LED element 3 in the Z direction. Fixing the lens substrate 7 to the support member 20 makes it easy to position the lens element 9 for each LED element 3, which is preferable. 【0046】 From the viewpoint of preventing damage to the LED elements 3 due to contact, it is preferable that the lens substrate 7 is fixed to a plurality of spaced-apart support members 20, as shown in Figure 5B. In other words, this configuration is preferable because, when arranging the support members 20 on the LED substrate 5 on which the LED elements 3 are arranged, the support members 20 can be easily arranged while avoiding the LED elements 3. 【0047】 The thickness of the support member 20 in the Z direction corresponds to the distance between the LED substrate 5 and the lens substrate 7. From the viewpoint of facilitating the incidence of the heating light L1 emitted by the LED element 3 onto the corresponding lens element 9, the thickness of the support member 20 in the Z direction is preferably 2 mm or less, and more preferably 1 mm or less. Furthermore, from the viewpoint of suppressing collisions between the LED element 3 and the lens substrate 7 when fixing the lens substrate 7 to the support member 20, the thickness is preferably 0.5 mm or more, and more preferably 1 mm or more. Note that the thickness of the support member 20 in the Z direction may differ among multiple lens substrates 7. 【0048】 When mounting the lens substrate 7, it is preferable that the lens element 9 has a convex shape on the opposite side from the LED element 3, i.e., on the -Z side, from the viewpoint of suppressing collision between the lens element 9 formed on the lens substrate 7 and the LED element 3. 【0049】 In addition, in view of the fact that the periphery of the LED element 3 becomes high temperature when the LED element 3 is lit, the adhesive for bonding the lens substrate 7 and the support member 20 preferably has high heat resistance. For example, the heat resistance of the adhesive is preferably 50°C or higher, and more preferably 100°C or higher. A ceramic-based adhesive can be cited as a suitable adhesive. 【0050】 In FIG. 5B, the distance dx by which the centers 3a of the respective LED elements 3 are separated from each other in the X direction, and the distance dy by which the centers 3a are separated from each other in the Y direction are schematically shown. Since the lens element 9 has a predetermined curvature and is arranged corresponding to the LED element 3, when the distances (dx, dy) by which the plurality of LED elements 3 are separated from each other become small, the respective lens elements 9 interfere with each other. FIG. 6 is a perspective view showing another configuration example of the lens element 9. When the separation distances (dx, dy) between the centers 3a of the LED elements 3 become small and the separation distances between the apexes 9a of the lens elements 9 become small, as shown in FIG. 6, in the direction parallel to the XY plane, the formation region of the lens element 9 decreases. More specifically, the length b1 of the lens element 9 in the X direction decreases. Although the length b1 in the X direction is shown in FIGS. 5A and 6, the same discussion is possible in the Y direction. 【0051】 For example, as shown in FIG. 6, when the length b1 of the lens element 9 with respect to the LED element 3 becomes small, the heating light L1 incident on the lens element 9 decreases, and it is considered that this affects the mode of propagation of the heating light L1 emitted by the LED element 3. 【0052】 In view of this point, in the light source unit 10, the LED density D defined by the following formula (1) L is 5 pieces / cm 2 or more and 15 pieces / cm 2 or less. More specifically, in the present embodiment, the LED density D in the heating group G1 L is within the above range. The LED density D LThis is obtained by dividing the actual number of LED elements 3 located within a first region C1, which is formed by virtually connecting the centers 3a of adjacent LED elements 3 when viewing a plurality of LED elements 3 facing the lens substrate 7 in the Z direction (see Figure 5B), by the area of ​​said region C1. LED density D L = Actual number of LED elements in the first region / Area of ​​the first region ... (1) 【0053】 Here, the "effective number of LED elements 3 within the first region C1" is calculated by adding up the regions where multiple LED elements 3 and the first region C1 overlap. By defining it this way, it is possible to consider the effect of interference between multiple lens elements 9 on the incident heating light L1 of the LED elements 3. To illustrate with the example in Figure 5B, the effective number of LED elements 3 located inside the first region C1 is 4, and if dx and dy are 4 mm, for example, the LED density D L 6.3 pieces / cm 2 Therefore, based on the above, the LED density D L It can also be considered as equivalent to the reciprocal of the product of the separation distance dx and the separation distance dy. 【0054】 In considering the arrangement of lens elements 9 corresponding to each LED element 3, the inventors considered the LED density D L By setting the range to the above-mentioned range, we found that it is possible to increase the temperature of the semiconductor substrate while suppressing the shortening of the lifespan of the LED element 3 compared to the conventional configuration in which the lens element 9 is not arranged. This point will be described in detail in the sections on Verification 1 and Verification 2 below. 【0055】 Furthermore, the inventors have found that, from the viewpoint of reducing the divergence angle of the heating light L1 by incidenting the heating light L1 onto the lens element 9 and heating the semiconductor substrate W1 more efficiently, it is preferable that the ratio R1 defined by the following equation (2) be 8.0 or less. This point will be described in detail in the Verification 3 section below. Ratio R1 = Length b1 of lens element 9 / Length a1 of LED element 3 …(2) 【0056】 [Verification 1] As mentioned above, as the distances dx and dy decrease, the area where the lens element 9 is formed relative to the LED element 3 decreases. In other words, the distances dx and dy, i.e., the LED density D L By varying the LED density D, it is possible to vary the formation region of the lens element 9 relative to the LED element 3. In this verification, the LED density D L By varying the settings, we investigated the change in the light reception rate of the semiconductor substrate W1 to the heating light L1 emitted by the LED element 3. This will be explained as Verification 1. In this verification, light reception rate was defined as the ratio of the light rays reaching the semiconductor substrate W1 to the total light rays output from the LED element 3 in a Lambertsian distribution, with the total light rays being set at 100%. 【0057】 [Verification 1] Figures 7 and 8 are diagrams showing the simulation conditions in Verification 1. Figure 8 corresponds to the view of the lens substrate 7 in Figure 7 in the Z direction. In this verification, a lens substrate 7 with 3 × 3 lens elements 9 formed thereon was used, as shown in Figures 7 and 8. 【0058】 In this verification, the separation distance (dx, dy) of each lens element 9 was changed to control the LED density D L By varying the LED density, we verified the change in the light-receiving rate of the semiconductor substrate W1 of the heating light L1 emitted by the LED element 3. In this verification, only one LED element 3 was placed at the position corresponding to the centrally located lens element 9. In reality, LED elements 3 are placed corresponding to each lens element 9, so the LED density D L The calculation was performed in the same manner as in Figure 5B, assuming that the LED elements 3 are positioned corresponding to all the lens elements 9. In Figures 7 and 8, the positions of the LED elements 3 corresponding to the outer lens elements 9 are schematically shown by dashed lines. 【0059】 This is to simplify the discussion of light reception efficiency. Specifically, by verifying the change in light reception efficiency of the heating light L1 emitted by the centrally located LED element 3, it is possible to verify the change in light reception efficiency when adjacent lens elements 9 interfere with each other. In this verification, it is assumed that even if a lens element is placed further outside of the outer lens element 9, the light emitted by the central LED element 3 hardly reaches that lens element. 【0060】 In this verification, the diameter of the semiconductor substrate W1 was set to 20 mm, and the distance in the Z direction between the semiconductor substrate W1 and the LED element 3 was set to 80 mm. The size of the LED element 3 was set to 1 mm × 1 mm, the length b1 of the lens element 9 was set to 4 mm, and the input current to the LED element 3 was set to 1 A. Here, the length b1 of the lens element 9 refers to the maximum length when the lens element 9 does not interfere with other lens elements 9. 【0061】 [Results of Verification 1] Figure 9 is a graph showing the results of Verification 1. In Figure 9, the horizontal axis is LED density D L The vertical axis shows the light-receiving efficiency of the semiconductor substrate W1. As shown in Figure 9, the LED density D L 4 pieces / cm 2 Within the following range, the light-receiving rate was shown to be constant. From this result, in this verification, the LED density D L 4 pieces / cm 2 Within the following range, each lens element 9 is spaced apart from each other, and the formation region of the lens elements 9 does not change. In other words, LED density D L 4 pieces / cm 2 Within the following range, LED density D L The change in [the variable] had little effect on the light-receiving rate. 【0062】 On the other hand, LED density D L 5 pieces / cm 2 Within the above range, LED density D L As the value increased, the light-receiving rate decreased. This is because the LED density D LThis is thought to be because the increase in this factor reduces the distance between the vertices 9a of each lens element 9, thereby decreasing the formation area of ​​the lens elements 9 relative to the LED element 3. In other words, it is thought that the amount of heating light L1 incident on the portion where each lens element 9 interferes decreases, and the amount of light directed toward the semiconductor substrate W1 decreases. 【0063】 According to Figure 9, LED density D L 4 pieces / cm 2 The light reception rate decreased significantly when it exceeded the limit. And the LED density D L As the size increases, the light-receiving rate decreases to 20 particles / cm 2 As a result, it can be seen that the decrease in light reception rate becomes smaller. This is because the LED density D L 20 pieces / cm 2 Therefore, it is thought that the interference between each lens element 9 increased, and the amount of light incident on the lens element 9 decreased. In that case, when the LED element 3 and the lens element 9 are arranged facing each other, the LED density D L 20 pieces / cm 2 The following is preferable. 【0064】 [Verification 2] From Verification 1, when the lens element 9 is placed relative to the LED element 3, the LED density is 4 LEDs / cm². 2 Exceeding 20 pieces / cm 2 The following range was suggested to be preferable. Therefore, in this verification, the LED density D in that range was considered. L The highest is 20 pieces / cm 2 Using this as a baseline, the effect of arranging the lens element 9 relative to the LED element 3 was compared and verified. In other words, in this verification, the LED density D L 20 pieces / cm 2 A reference example shows the arrangement of LED elements 3 and the absence of lens elements 9, and the arrangement of LED density D with lens elements 9 in place. L In each embodiment in which the temperature was reduced, the temperature T reached by the semiconductor substrate W1 W , and LED lifespan L T This was verified. 【0065】 (Example 1) This verification was performed under the simulation conditions described with reference to Figures 7 and 8, similar to Verification 1. 【0066】 In Example 1, the LED density D L 5 pieces / cm 2 In that case, the temperature T reached by the LED element 3 is... j And the temperature T reached by the semiconductor substrate W1 W This was verified. Also, the temperature T reached by LED element 3 was verified. j Based on this, the lifespan L of LED element 3 T This was calculated. 【0067】 Lifespan L T The LED temperature T is determined according to the Arrhenius equation shown in equation (3) below. j It depends on the lifespan L when the light output deteriorates. T Since this depends on the reaction rate K, taking the reciprocal of equation (3) below yields equation (4). In equations (3) and (4) below, K is the reaction rate, A and B are constants, Ea is the activation energy, k is the Boltzmann constant, and T is the absolute temperature. 【number】 【0068】 Based on equation (4) above, the time until the illuminance of the LED element 3 decreases to 85% is calculated as the lifespan L. T This yields Figure 10. Figure 10 shows the achievable temperature T of the LED. j and LED lifespan L T This graph shows the relationship between the LED temperature T. j Based on this, lifespan L T You can obtain this. 【0069】 (Example 2) LED density D L 10 pieces / cm 2 Except for the point that was stated, the procedure was carried out under the same conditions as in Example 1. 【0070】 (Example 3) LED density DL 15 pieces / cm 2 Except for the point that was stated, the procedure was carried out under the same conditions as in Example 1. 【0071】 (Example 4) LED density D L 10 pieces / cm 2 The experiment was carried out under the same conditions as in Example 1, except that the input current to LED element 3 was set to 1.5A. 【0072】 (See Example 1) LED density D L 20 pieces / cm 2 The procedure was carried out under the same conditions as in Example 1, except that the LED elements 3 were arranged in such a manner, and the lens substrate 7 and lens elements 9 were not arranged. For the sake of clarity, the LED density D in Reference Example 1 L This was obtained by dividing the actual number of LED elements located within the first region formed by virtually connecting the centers of the LED elements by the area of ​​said region. In other words, except for the point where the lens substrate 7 is not placed, the LED density D L This can be defined in the same way as in Example 1. 【0073】 [Results of Verification 2] Table 1 below is a graph showing the results of Verification 2. Table 1 shows the temperature T reached by the LEDs obtained in each example and reference example. j and the temperature T reached by the semiconductor substrate W1 W and the reached temperature T j The lifespan L of the LED obtained based on this T This is shown. [Table 1] 【0074】 According to Table 1, in Reference Example 1 where the lens substrate 7 is not placed, the LED temperature T j The temperature reaches 70°C, and the LED lifespan is L T The time was 11,000 hours. In contrast, in Example 1, the LED temperature T jWhile suppressing it to 35°C, heating of the semiconductor substrate W1 comparable to that in Reference Example 1 was achieved. That is, in Example 1, while realizing heating comparable to that in Reference Example 1, the life L of the LED element T resulted in being longer than that in Reference Example 1. 【0075】 This is presumably because, in Example 1, due to the lens element 9 being arranged to face the LED element 3, the divergence angle of the heating light L1 emitted by the LED element 3 was reduced, and thus the heating light L1 traveling in a direction different from the semiconductor substrate W1 decreased. That is, in Example 1, the heating light L1 emitted by the LED element 3 was condensed by the lens element 9, and thus the semiconductor substrate W1 was efficiently irradiated with the heating light L1. 【0076】 LED density D L being 5 pieces / cm 2 in Example 1 where it was set, considering that heating of the semiconductor substrate W1 comparable to that in Reference Example 1 could be achieved, the LED density D L is preferably at least 5 pieces / cm 2 or more. That is, when the LED density D L is 4 pieces / cm 2 or less, it is considered that the number of LEDs arranged on the LED substrate 5 is small in the first place, and the heating light for the semiconductor substrate W1 is likely to be insufficient. 【0077】 Also, in Examples 2 and 3, by increasing the LED density D L more than that in Example 1, the reaching temperature T of the semiconductor substrate W1 W was increased. Furthermore, in both Examples 2 and 3, although the reaching temperature T of the semiconductor substrate W1 W was increased, the reaching temperature T of the LED element j is lower than the result of Reference Example 1. That is, in Examples 2 and 3, while the life L of the LED element T was extended longer than that in Reference Example 1, the reaching temperature T of the semiconductor substrate W1 W was increased. 【0078】 In addition, in Example 4, by increasing the input current to the LED element, the reaching temperature T of the semiconductor substrate W1 was higher than that in Example 2. W Even in this case, the LED reaching temperature T j was equivalent to that in Reference Example 1. That is, in Example 4, it was shown that the reaching temperature T W of the semiconductor substrate W1 could be increased while suppressing the shortening of the life of the LED element. 【0079】 From the above results, it was shown that by arranging the lens element 9 opposite to the LED element 3, the heating light L1 emitted by the LED element 3 could be efficiently irradiated onto the semiconductor substrate W1. As a result, it is possible to increase the temperature of the semiconductor substrate while reducing the LED density D L and suppressing the shortening of the life of the LED element compared to the conventional configuration in which the lens element 9 is not arranged. 【0080】 And considering the results of Verification 2 and 1 together, it can be said that the LED density D L is preferably 5 or more and 15 or less per cm 2 ². 2 【0081】 [Verification 3] In the above, the size of the LED element 3 was set to 1 mm × 1 mm, and the maximum length of the lens element 9 was verified to be 4 mm. In this case, the ratio R1 is 4. Here, considering the light reception rate of the semiconductor substrate W1, for example, it seems preferable to reduce the LED element 3 and increase the ratio R1. However, reducing the LED element 3 means a decrease in the light emission amount of the LED element 3. That is, it can be said that the ratio R1 affects the amount of received light of the heating light L1 incident on the semiconductor substrate W1. Here, the amount of received light corresponds to the amount of heat incident on the semiconductor substrate W1 by the heating light L1 and can be defined as the product of the light reception rate of the semiconductor substrate W1 and the area of the LED element 3. By defining it in this way, it is possible to consider the change in the light emission amount of the LED element 3 when the length of the LED element 3 is varied. In this verification, by varying the ratio R1, the influence on the amount of received light of the semiconductor substrate W1 was verified, and thus will be described below. 【0082】 Specifically, in this verification, the change in the amount of light received with respect to the ratio R1 was investigated by performing simulations with the length b1 of the lens element 9 set to 4 mm and the length a1 of the LED element 3 varied. Similarly, the change in the amount of light received with respect to the ratio R1 was investigated by setting the length b1 of the lens element 9 to 6 mm and the length a1 of the LED element 3 varied. 【0083】 Figure 11 is a graph showing the results of Verification 3. In Figure 11, the horizontal axis shows the ratio R1 and the vertical axis shows the amount of light received. Note that in Figure 11, the amount of light received is shown in a normalized form. As shown in Figure 11, it can be seen that the amount of light received decreases as the ratio R1 increases. This is thought to be because although the light reception rate increases as the LED element 3 becomes smaller relative to the lens element 9, the effect of the decrease in the light emission amount of the LED element 3 becomes larger. According to Figure 11, it can be seen that at least 60% of the amount of light received can be maintained in the range where the ratio R1 is 8.0 or less. In light of this, it is preferable that the ratio R1 be 8.0 or less. Furthermore, from the viewpoint of increasing the amount of light received, it is even more preferable that the ratio R1 be 5.0 or less. 【0084】 Typically, considering that the length b1 of the lens element 9 is greater than the length a1 of the LED element 3, it is preferable that the ratio R1 exceeds 1.0. Also, designing a fine lens element 9 tends to increase costs. In light of this, it is more preferable that the ratio R1 be 2.0 or higher, and particularly preferable that be 4.0 or higher. 【0085】 As shown in Figure 11, the amount of light received showed a similar trend with respect to the ratio R1 when the length b1 of the lens element 9 was 4 mm and when it was 6 mm. In other words, from the viewpoint of increasing the amount of light received, the length b1 of the lens element 9 and the length a1 of the LED element 3 are not limited, and it is preferable to discuss this in terms of the ratio R1. 【0086】 [Summary of Verification] The above verification showed that by arranging the lens element 9 in relation to the LED element 3, it is possible to heat the semiconductor substrate W1 to a higher temperature while suppressing the shortening of the LED element 3's lifespan compared to a conventional configuration without the lens element 9. In other words, one could consider adding LED elements by reducing the spacing between them in order to irradiate the semiconductor substrate W1 with more heating light, but this method tends to increase the temperature of the LED elements, leading to a shortened lifespan for the LED elements. In contrast, by arranging the lens element 9 opposite the LED element 3, it becomes possible to irradiate the semiconductor substrate W1 with more heating light L1, thereby heating the semiconductor substrate W1 to a higher temperature while suppressing the shortening of the LED elements' lifespan caused by the reduced spacing between them. 【0087】 Furthermore, when the lens element 9 is placed relative to the LED element 3, the LED density D of the LED element 3 is located opposite the lens substrate 7. L 5 pieces / cm 2 More than 15 pieces / cm 2 The following has been shown to be preferable. Furthermore, from the viewpoint of incidenting the heating light L1 emitted by the LED element 3 onto the lens element 9, it is preferable that the ratio R1 of the length a1 of the LED element 3 to the length b1 of the lens element 9 be 8.0 or less. 【0088】 In light of the above verification results, by positioning the lens element 9 in correspondence with the LED element 3, the divergence angle of the heating light L1 is reduced, and the amount of heating light L1 traveling in a direction different from that of the semiconductor substrate W1 is decreased, resulting in an increase in the temperature of the semiconductor substrate W1. In the above verification, the diameter of the semiconductor substrate W1 was assumed to be 20 mm, and the distance in the Z direction between the semiconductor substrate W1 and the LED element 3 was assumed to be 80 mm. However, when the amount of heating light L1 traveling in a direction different from that of the semiconductor substrate W1 is reduced by the lens element 9, it is possible to increase the temperature reached by the semiconductor substrate W1, and the present invention is not limited to the above simulation conditions. 【0089】 Based on the above verification, it can be understood that the configuration described in the first embodiment allows for a higher temperature of the semiconductor substrate while suppressing the shortening of the LED element's lifespan compared to conventional configurations. In other words, according to the first embodiment, a light source unit and optical heating device can be realized that can heat the semiconductor substrate W1 to a higher temperature while suppressing the shortening of the LED element's lifespan compared to conventional configurations in which the lens element 9 is not arranged. 【0090】 [Differentiation] The following describes modifications of the optical heating device 1 and the light source unit 10. 【0091】 <1> Figure 12 is a diagram showing a modified example of the light source unit 10, following Figure 2, and Figure 13 is a diagram showing an enlarged portion of Figure 12. In Figures 12 and 13, the position of the semiconductor substrate W1 is schematically shown by a dashed line. In the above, the LED element 3 of the light source unit 10 was described as being arranged in a region facing the semiconductor substrate W1. However, as shown in Figure 13, the light source unit 10 may also have an LED element 4 arranged in a region outside the semiconductor substrate W1 when viewed in the Z direction. 【0092】 In Figures 12 and 13, as described in the first embodiment above, lens elements 9 are arranged in correspondence with a plurality of LED elements 3 facing the peripheral edge of the semiconductor substrate W1. Similarly, lens elements 19 are arranged in correspondence with LED elements 4. The configuration of lens element 19 is the same as that of lens element 9. 【0093】 In this modified example, from the viewpoint of facilitating the direction of the heating light L1 emitted by the LED element 4, which is located in the region outside the semiconductor substrate W1, towards the semiconductor substrate W1, the lens element 19, which is positioned in correspondence with the LED element 4, may be positioned such that its vertex approaches the center of the semiconductor substrate W1 from the optical axis of the LED element 4. Specifically, with respect to the direction toward the center of the semiconductor substrate W1, the amount of deviation between the optical axis of the LED element 4 and the central axis of the lens element 19 may be 20% to 50% of the length of the LED element 4. For example, if the LED element 4 has a size of 1 mm square, the amount of deviation is 0.4 mm. 【0094】 Even in the LED elements 4 located in the region outside the semiconductor substrate W1, the LED density D L The same discussion as with LED element 3 is possible regarding the ratio R1. 【0095】 <2> In the above description, the light source unit 10 is positioned on the +Z side of the semiconductor substrate W1, and the light source unit 10 emits heating light L1 in the -Z direction. However, this is arbitrary. For example, the light source unit 10 may emit heating light L1 in the +Z direction, and the semiconductor substrate W1 may be positioned on the +Z side of the light source unit 10. 【0096】 <3> In the above description, the lens element 9 was formed on the -Z side of the lens substrate 7 and was described as having a convex shape on the -Z side. However, from the viewpoint of reducing aberrations and irradiating the semiconductor substrate W1 with heating light L1 with greater precision, the lens element 9 may also be formed on the +Z side of the lens substrate 7 and have a convex shape on the +Z side. 【0097】 <4> The inclusion of a chamber 11 in the optical heating device 1 is optional. For example, if heating of the semiconductor substrate W1 is performed in an atmospheric environment, such as when it is not necessary to replace the surrounding area of ​​the semiconductor substrate W1 with a process gas such as nitrogen, the chamber 11 is not required. In other words, the present invention is not limited to whether or not the semiconductor substrate W1 and the light source unit 10 are housed in the chamber 11. 【0098】 <5> Figure 14 is a diagram showing another modified example of the light source unit 10, following Figure 2. In the above description, the light source unit 10 was described as having multiple heating groups G1. However, in the present invention, this is optional, and for example, as shown in Figure 14, all LED elements 3 may be arranged on the LED substrate 5 so as to overlap with a single lens substrate 7, and the light source unit 10 may have only one heating group G1. 【0099】 Furthermore, as described with reference to Figure 3 in Figure 14, the heating group G1 may be configured such that the LED elements 3 are arranged in close proximity to each other. 【0100】 <6> The configuration according to the present invention is not limited to the illustrated configuration. Furthermore, the above embodiments and each modified configuration can be implemented by combining them as appropriate. [Explanation of Symbols] 【0101】 1 : Optical heating device 3,4,13: LED elements 5: LED board 7: Lens substrate 9,19: Lens element 10: Light source unit 11: Chamber 12: Support Unit 15: Heatsink 20: Support member 21: Adhesive

Claims

[Claim 1] A light source unit that irradiates a semiconductor substrate with light to perform a heating treatment on the semiconductor substrate, Multiple LED elements that emit the aforementioned light in the first direction, An LED substrate on which multiple LED elements are arranged, A lens substrate arranged opposite to a plurality of LED elements in the first direction, The lens substrate comprises a plurality of lens elements formed in a convex shape at positions corresponding to each of the LED elements, which reduce the divergence angle of the light emitted by the LED elements, When viewed in the first direction, the LED density obtained by dividing the actual number of LED elements located within the first region, which is formed by virtually connecting the centers of a plurality of adjacent LED elements facing the lens substrate, by the area of ​​the first region, is 5 LEDs / cm². 2 More than 15 pieces / cm 2 The following: A light source unit characterized in that, with respect to a direction parallel to a plane perpendicular to the first direction, the ratio obtained by dividing the length of the LED element by the length of the lens element corresponding to the LED element is 8.0 or less. [Claim 2] The LED substrate is provided with a support member that is arranged on the LED substrate, extends beyond the LED element in the first direction, and supports the lens substrate, The light source unit according to claim 1, characterized in that the lens substrate is fixed to the support member via an adhesive. [Claim 3] The light source unit according to claim 1 or 2, characterized in that the lens element has a convex shape on the side opposite to the LED element. [Claim 4] The light source unit according to claim 3, characterized in that the separation distance between the LED substrate and the lens substrate in the first direction is 2 mm or less. [Claim 5] The system has multiple heating groups in which multiple LED elements are arranged in close proximity to each other. In at least one of the heating groups, the LED density is 5 LEDs / cm². 2 More than 15 pieces / cm 2 The light source unit according to claim 1 or 2, characterized in that the ratio is 8.0 or less. [Claim 6] The light source unit according to claim 1 or 2, characterized in that the LED element is arranged facing the peripheral edge of the semiconductor substrate. [Claim 7] A light heating device comprising the light source unit according to claim 1 or 2.

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