JP7615455B2 - Light irradiation device - Google Patents

Description

The present invention relates to a light irradiation device, and in particular to a light irradiation device that uses an LED element as a light source to irradiate light onto a substrate to be processed.

In the semiconductor manufacturing process, various heat treatments such as film formation, oxidation and diffusion, modification, and annealing are performed on substrates such as semiconductor wafers. These processes often use a heat treatment method that uses light irradiation, which allows for non-contact processing. Patent Document 1 below discloses an optical heating device that heats semiconductor wafers with light emitted from LED elements.

Special table 2018-523305 publication

Devices used in the semiconductor manufacturing process to irradiate light onto semiconductor wafers are expected to be able to irradiate the entire surface (particularly the main surface) of the semiconductor wafer with light of the same intensity so that the entire semiconductor wafer is processed uniformly.

The inventors therefore conducted extensive research into a light irradiation device that can irradiate the entire substrate to be processed, such as a semiconductor wafer, with more uniform light, and discovered the following problems. The following will be explained with reference to the drawings.

Figure 9 is a schematic cross-sectional view of a conventional light irradiation device 100 when viewed in the Y direction. As shown in Figure 9, the light irradiation device 100 includes a chamber 101 and a plurality of LED elements 102 arranged on an LED substrate 103. The chamber 101 also includes a light-transmitting window 101a for introducing light emitted from the LED elements 102 to the inside, and a support member 104 for supporting the substrate W1 to be processed inside.

In the following description, the direction in which the LED board 103 and the substrate W1 to be processed face each other is defined as the Z direction, the direction in which the support member 104 faces each other is defined as the X direction, and the direction perpendicular to the X and Z directions is defined as the Y direction. In addition, since the arrangement of the LED elements 102 in the light irradiation device 100 is the same when viewed in the X direction and when viewed in the Y direction, only the structure when viewed in the Y direction will be described unless otherwise necessary.

In this specification, when expressing a direction, if there is a distinction between positive and negative directions, the direction is described with a positive or negative sign, such as "+Z direction" and "-Z direction." In addition, when expressing a direction without distinguishing between positive and negative directions, it is simply described as "Z direction."

In the light irradiation device 100 shown in FIG. 9, the light emitted from the LED element 102 and reaching the peripheral end W1e side of the substrate W1 to be processed is less than the central portion W1c side of the substrate W1 to be processed. As a result, the light intensity on the peripheral end W1e side is significantly lower than that on the central portion W1c side.

Therefore, the above-mentioned Patent Document 1 discloses a configuration in which LED elements 102 are arranged over a wider area of the LED substrate 103 than the area facing the substrate W1 to be processed, in order to suppress temperature variations between the central portion W1c and the peripheral portion W1e of the substrate W1 to be processed.

Figure 10 is a schematic cross-sectional view of a conventional light irradiation device 100 with a different configuration from that of Figure 9, viewed in the Y direction. The light irradiation device 100 shown in Figure 10 irradiates the central portion W1c side and the peripheral portion W1e side of the substrate W1 to be processed in the same manner with light emitted from the LED elements 102, so that the entire substrate W1 to be processed can be irradiated with light uniformly.

However, the light irradiation device 100 shown in FIG. 10 requires a larger chamber 101 and LED substrate 103 than the light irradiation device 100 shown in FIG. 9, which results in a larger device overall.

As a method for suppressing the decrease in light intensity at the peripheral edge W1e, it is possible to increase the intensity of light irradiated around the peripheral edge W1e of the substrate W1 by arranging the LED elements 102 at a high density only in the area where the LED elements 102 that irradiate light toward the peripheral edge W1e of the substrate W1 to be processed are arranged.

Figure 11 is a schematic cross-sectional view of a conventional light irradiation device 100 having a different configuration from those in Figures 9 and 10, as viewed in the Y direction. The light irradiation device 100 shown in Figure 11 has more overlapping light on the peripheral edge W1e side of the substrate W1 to be processed, so that the decrease in the intensity of the light irradiated to the peripheral edge W1e of the substrate W1 to be processed is suppressed.

However, in the light irradiation device 100 shown in FIG. 11, although the overall size of the device is not increased, a region W1d is formed between the central portion W1c and the peripheral portion W1e where the light intensity is higher than that of the central portion W1c and the peripheral portion W1e due to the increased amount of overlapping light. The relationship of the relative intensities of the light irradiated to the substrate W1 to be processed is described in detail with reference to FIG. 6 in [Mode for carrying out the invention].

If the light intensity on the peripheral end W1e side is only slightly lower than on the central end W1c side, it is possible to take measures such as using an optical component such as a mirror to compensate for the decrease in light intensity with reflected light. However, it is difficult to reduce the light intensity only in a partial area inside the peripheral end W1e, and measures such as placing an optical component that blocks or scatters some of the light may actually worsen the uniformity of the light intensity distribution.

In view of the above problems, the present invention aims to provide a light irradiation device that suppresses uneven irradiation of light irradiated from an LED element to a substrate to be processed without increasing the size of the entire device.

The light irradiation device of the present invention comprises:
A light irradiation device that irradiates a substrate to be processed with light,
a chamber for accommodating the substrate to be processed;
a support member for supporting the substrate to be processed within the chamber;
an LED substrate disposed opposite the substrate to be processed supported by the support member;
a plurality of LED elements arranged on a main surface of the LED substrate so as to emit light toward a main surface of the substrate supported by the support member;
When the region of the LED substrate in which the LED elements are arranged is divided into a plurality of concentric regions, the plurality of regions are:
An outermost first region;
a second region that is inside the first region and separated from the first region, and has a value obtained by dividing a total value of power supplied to the second region by an area of the second region that is smaller than that of the first region;
The present invention is characterized in that it includes a third region sandwiched between the first region and the second region, the total value of the power supplied thereto divided by the area of which is smaller than that of the second region.

In this specification, the substrate to be processed and the LED substrate facing each other includes not only cases where their respective main surfaces face each other directly, but also cases where they face each other via a member that transmits the light emitted from the LED element, such as a transparent window formed in the wall of the chamber.

The greater the value obtained by dividing the total power supply to the region by its area, the higher the brightness of the region. In other words, with the above configuration, the brightness of the LED elements in each region is first region > second region > third region.

If the brightness of the area where light is irradiated around the peripheral edge is simply increased, as described above with reference to FIG. 11, some areas will be irradiated with light of high intensity. Therefore, by providing a third area between the first and second areas, which has a lower brightness than either area, the light intensity is prevented from becoming high in the area where the light emitted from the LED elements arranged in the first area and the light emitted from the LED elements arranged in the second area overlap. Therefore, the uniformity of the light irradiated to the main surface of the substrate to be processed can be improved.

Furthermore, with the above configuration, the size of the LED element placement area is not important, and can be achieved by adjusting the area ratio of each area and the power supplied to each area, so there is no need to configure the chamber or LED substrate to be large. In other words, the entire device can be made smaller.

The light irradiation device is
the number of the LED elements per unit area in the second region is smaller than the number of the LED elements per unit area in the first region;
The number of the plurality of LED elements per unit area in the third region may be smaller than the number of the plurality of LED elements per unit area in the second region.

The higher the number of LED elements per unit area, i.e., the higher the arrangement density, the greater the number of LED elements that irradiate light to the same region of the main surface of the substrate to be processed supported by the support member. In other words, the above configuration increases the intensity of the light emitted from the LED elements in the first region and irradiated around the peripheral edge of the substrate to be processed. Therefore, for the same reasons as described above, it is possible to improve the uniformity of the light intensity distribution irradiated over the entire main surface of the substrate to be processed.

The light irradiation device is
a cooling member provided on a surface of the LED board opposite to a surface on which the LED elements are mounted, the cooling member having an inlet for introducing a cooling medium for cooling the LED elements into an inside of the LED board, an outlet for discharging the cooling medium to the outside of the LED board, and a flow path connecting the inlet and the outlet so that the cooling medium passes from the inlet through the first region, the second region, and the third region of the LED board in this order;
The cooling medium may be supplied from the inlet of the LED board into the flow path.

LED elements have the characteristic that, even when the same power is supplied, their characteristics vary with temperature, and the higher the temperature, the lower the brightness. Therefore, when it is desired to uniformly irradiate light onto a substrate to be processed using a light irradiation device that uses LED elements as a light source, it is preferable to adjust the temperature distribution of the entire LED element to be uniform so that all LED elements light up at the desired brightness.

The temperature of the LED elements depends on the power supplied per unit area, so the temperatures of the LED elements arranged in the first area, second area, and third area will be lower. Therefore, to make the temperature distribution of the entire LED element uniform, it is necessary to focus on cooling the LED elements arranged in the first area.

Moreover, in order to maintain higher brightness, many light irradiation devices that use LED elements as light sources are equipped with cooling members such as air-cooled heat sinks and water-cooled flow paths on the LED board. In particular, for light irradiation devices that require high output and use a large number of LED elements, such as those used in the heating process of semiconductor wafers, a water-cooled cooling mechanism is generally used, which has better heat dissipation performance than an air-cooled type.

The cooling medium that is fed from the supply mechanism into the inlet gradually increases in temperature as it flows through the flow path while absorbing heat generated by the LED elements, and its ability to absorb heat decreases as it approaches the outlet. Therefore, it is preferable that the flow path is configured so that the cooling medium that is fed into the inlet immediately flows through the area that needs to be most cooled. In the present invention, for example, water or a fluorine-based inert liquid can be used as the cooling medium.

With the above configuration, the cooling medium absorbs more heat in the first region where the power supplied per unit area is high. This allows the first region, where the temperature is the highest, to be cooled intensively, further improving the uniformity of the temperature distribution across the entire LED board.

In addition, the power supplied per unit area is greatest in the first region, followed by the second region and then the third region, and so the temperatures increase in that order. For this reason, by passing the cooling medium through the first region, followed by the second region and then the third region in that order, the higher the temperature of the region, the more heat is absorbed by the cooling medium, improving the uniformity of the overall temperature distribution.

The flow path may include a path that is connected in part by a drainage pipe outside the LED substrate between the inlet and the outlet. For example, if the regions are formed concentrically from the peripheral end side in the order of the first region, third region, and second region, when forming the entire flow path within the LED substrate in the above order, the third region must be passed when going from the first region to the second region. Therefore, in order to realize a flow path that connects the first region, second region, and third region in that order, the flow path may include a drainage pipe that connects the first region and second region outside the LED substrate in part.

It is also possible to form a bypass path from the first region to the second region in part of the third region so that the cooling medium flows in the above order. In this specification, the bypass path is provided solely for the purpose of moving between regions, not for cooling the elements, so even in the above configuration, it means that the flow will be from the first region to the second region.

In the above light irradiation device,
The material of the LED substrate may be mainly composed of aluminum nitride or silicon nitride.

In this specification, "major component" refers to the material with the highest content.

The above configuration allows the heat generated by the LED elements to be efficiently transferred to the cooling medium flowing through the flow path.

In the above light irradiation device,
The LED substrate may have a hole connecting the main surfaces of the LED substrate.

With the above configuration, a radiation thermometer can be placed on the opposite side of the LED board to measure the temperature of the main surface of the substrate being processed, allowing processing to proceed while checking whether light is being irradiated evenly over the entire substrate being processed.

Even in cases other than heat treatment, when light is irradiated onto a substrate, the substrate absorbs some of the irradiated light, causing slight changes in surface temperature. Therefore, radiation thermometers are expected to be used not only to measure temperature changes during heat treatment, but also in cleaning and modification (hardening) processes.

The light irradiation device is
The LED element may have a main emission wavelength in the range of 300 nm to 1050 nm.

In this specification, "main emission wavelength" refers to the wavelength at which the emitted light has the highest intensity.

In particular, semiconductor wafers made of silicon (Si) (hereafter referred to as "silicon wafers") have a high absorptance and low transmittance for light in the ultraviolet to visible wavelength range, but when the wavelength is longer than 1100 nm, the absorptance drops sharply and the transmittance increases. As shown in FIG. 3, which is referred to in the explanation of the "Form for carrying out the invention," when light with a wavelength of 1100 nm or more is irradiated onto a silicon wafer, approximately 50% of the light passes through the silicon wafer. For this reason, when a silicon wafer is heat-treated, it is preferable that the main emission wavelength of the light emitted from the LED element is 1050 nm or less.

In addition, the absorption rate of silicon wafers for light with wavelengths of less than 300 nm drops to about 10% at its lowest. Therefore, to ensure an absorption rate of at least 25%, it is preferable that the main emission wavelength of the light emitted from the LED element is 300 nm or longer.

The light irradiation device has the above configuration, allowing silicon wafers to be efficiently heat-treated.

The present invention provides a light irradiation device that suppresses unevenness in the light irradiated from the LED element to the substrate to be treated, without increasing the size of the entire device.

2 is a cross-sectional view of the configuration of an embodiment of a light irradiation device when viewed in the Y direction. FIG. This is a diagram of the LED substrate as seen from the -Z side. 1 is a graph showing spectra of absorptance and transmittance of light of a silicon wafer. This is a drawing of the cooling member as seen from the +Z side. 11 is a graph showing an example of the relative intensity of light irradiated onto the main surface of the substrate to be processed in each configuration. 2 is a cross-sectional view of the configuration of an embodiment of a light irradiation device when viewed in the Y direction. FIG. This is a diagram of the LED substrate as seen from the -Z side. This is a drawing of the cooling member as seen from the +Z side. FIG. 11 is a schematic cross-sectional view of a conventional light irradiation device as viewed in the Y direction. FIG. 11 is a schematic cross-sectional view of a conventional light irradiation device as viewed in the Y direction. FIG. 11 is a schematic cross-sectional view of a conventional light irradiation device as viewed in the Y direction.

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

[First embodiment]
Fig. 1 is a cross-sectional view of the configuration of one embodiment of a light irradiation device 1 when viewed in the Y direction. As shown in Fig. 1, the light irradiation device 1 of the first embodiment includes a chamber 10 in which a substrate W1 to be processed is accommodated, a plurality of LED elements 11, an LED substrate 12 on which the LED elements 11 are mounted, a radiation thermometer 14, and a supply mechanism 15. The first embodiment will be described on the assumption that the substrate W1 to be processed is a silicon wafer, but the substrate W1 may be a semiconductor wafer made of a material other than silicon, a glass substrate, or the like.

In the following explanation, as shown in Figure 1, the direction in which the LED board 12 and the substrate W1 to be processed face each other is defined as the Z direction, the direction in which the pair of support members 13 face each other is defined as the X direction, and the direction perpendicular to the X and Z directions is defined as the Y direction. In addition, as shown in Figure 2 described later, the arrangement of the LED elements 11 in the light irradiation device 1 has the same structure when viewed in the X direction and when viewed in the Y direction, so unless otherwise necessary, only the structure when viewed in the Y direction will be explained.

Similarly, below, when expressing a direction, if a distinction is made between positive and negative, it is written with a positive or negative sign, such as "+Z direction" and "-Z direction", and when expressing a direction without distinguishing between positive and negative, it is simply written as "Z direction".

As shown in FIG. 1, the chamber 10 has a support member 13 that supports the substrate W1 inside. The support member 13 supports the substrate W1 so that the main surface W1a of the substrate W1 is positioned on the XY plane.

The support member 13 supports the substrate W1 to be processed in any manner so long as its main surface W1a is positioned on the XY plane. For example, the support member 13 may have multiple pin-shaped protrusions that support the substrate W1 at points. Here, the main surface W1a is the surface on which circuit elements, wiring, etc. are formed and on which the light emitted from the LED elements 11 is irradiated.

The chamber 10 also has a light-transmitting window 10a on the +Z side wall for taking in the light emitted from the LED element 11. The chamber 10 may have any shape, such as a cylindrical shape or a square tube shape.

The multiple LED elements 11 are arranged on the -Z side main surface of the LED substrate 12, which is arranged to face the main surface W1a of the substrate W1 to be processed, which is supported by the support member 13.

The light-transmitting window 10a of the chamber 10 is configured to face the main surface W1a of the substrate W1 to be processed, which is supported by the support member 13, as shown in FIG. 1. In other words, the light emitted from the LED element 11 is irradiated onto the main surface W1a of the substrate W1 to be processed through the light-transmitting window 10a.

Figure 2 is a drawing of the LED board 12 as viewed from the -Z side. As shown in Figure 2, the multiple LED elements 11 are arranged point-symmetrically with respect to the center of the LED board 12. The arrangement area of the LED elements 11 is divided into three concentric areas: the outermost first area A1, the second area A2 inside the first area A1 and spaced apart from the first area A1, and the third area A3 sandwiched between the first area A1 and the second area A2. Note that in Figure 2, the boundaries of each area (A1, A2, A3) are shown by dashed lines, but this is shown for the purpose of explanation and is not shown on the actual LED board 12.

As shown in FIG. 2, each region (A1, A2, A3) is arranged so that the number of LED elements 11 per unit area, i.e., the arrangement density of the LED elements 11, satisfies the relationship of first region A1>second region A2>third region A3.

In the first embodiment of the light irradiation device 1, the ratio of the radial width of each region (A1, A2, A3) to the radius of the LED substrate 12 is A1: 16%, A2: 66%, and A3: 18%. From the viewpoint of improving the uniformity of the light, it is preferable that this ratio is A1: 20% or less, A2: 60% or more, and A3: 20% or less.

The number of LED elements 11 arranged in the second area A2 is set to 1, and the ratio of the number of elements in each area (A1, A2, A3) is configured to be A1:A2:A3 = 1.5:1.0:0.3. From the viewpoint of improving the uniformity of light, it is preferable that the number of LED elements 11 in the first area A1 is 1.2 to 2.0 times the number of LED elements 11 in the second area A2, and the number of LED elements 11 in the third area A3 is 0.1 to 0.5 times the number of LED elements 11 in the second area A2.

Furthermore, the LED elements 11 in each region (A1, A2, A3) are supplied with power from a power supply source (not shown) so that the ratio of the total power supplied to all the LED elements 11 arranged in the second region A2 is 1, and the ratio of the total power supplied to all the arranged LED elements 11 is A1:A2:A3 = 1.5:1.0:0.3. In other words, the ratio of the total power supplied divided by the area of the region is first region A1>second region A2>third region A3. As a result, the luminance of each region (A1, A2, A3) is first region A1>second region A2>third region A3. From the viewpoint of improving the uniformity of light, it is preferable that the total power supplied to the first region A1 is 1.2 to 2.0 times the total power supplied to the second region A2, and the total power supplied to the third region A3 is 0.1 to 0.5 times the total power supplied to the second region A2.

Figure 3 is a graph showing the spectrum of the absorptance and transmittance of a silicon wafer for light, and is a graph of the absorptance and transmittance of a silicon wafer on which no elements or wiring are formed. In Figure 3, the solid line corresponds to the absorptance, and the dashed line corresponds to the transmittance. As shown in Figure 3, the absorptance of a silicon wafer exceeds the transmittance for light in the wavelength band of 1100 nm or less, and the transmittance exceeds the absorptance for light in the wavelength band of 1100 nm or more. Therefore, when the substrate W1 to be processed is a silicon wafer and the light irradiation device 1 is used for heat treatment, it is preferable that the main emission wavelength of the light emitted from the LED element 11 is 1050 nm or less.

In addition, silicon wafers have a significantly low absorptivity for light in the wavelength band less than 300 nm. For this reason, when the substrate W1 to be processed is a silicon wafer and the light irradiation device 1 is used for heat treatment, it is preferable that the main emission wavelength of the light emitted from the LED element 11 is 300 nm or longer.

The light irradiation device 1 of the first embodiment is a device for heat-treating silicon wafers, and for the reasons mentioned above, is equipped with an LED element 11 that emits light with a main emission wavelength of 395 nm. However, depending on the intended use, an LED element 11 with a main emission wavelength other than 395 nm may be equipped. In addition, the light irradiation device 1 may be equipped with a mixture of LED elements 11 with different main emission wavelengths.

As shown in Figures 1 and 2, the LED board 12 has an observation hole 12a in the center that connects the main surfaces of the LED board 12 in order to measure the temperature of the main surface W1a of the substrate W1 to be processed by a radiation thermometer 14 arranged on the +Z side of the LED board 12. The observation hole 12a in the first embodiment is formed with a diameter of 15 mm, but in relation to the arrangement area of the LED elements 11, the measurement range of the radiation thermometer 14, and the diameter of the substrate W1 to be processed whose temperature is to be measured, it is preferable that the diameter of the observation hole 12a is within the range of 5 mm to 30 mm.

The LED board 12 is provided with a cooling member 12z on the side opposite to the side on which the LED elements 11 are mounted, the cooling member 12z having an inlet 12p, an outlet 12q, and a flow path 12c connecting the two.

As shown in FIG. 1, the supply mechanism 15 is connected to the inlet 12p and outlet 12q formed in the cooling member 12z by a water pipe 15a. As shown by the dashed arrow in FIG. 1, the supply mechanism 15 flows cooling water C1 into the inlet 12p, and receives cooling water C2 discharged from the outlet 12q through a flow path 12c formed in the cooling member 12z.

In the first embodiment, the flow path 12c of the cooling member 12z is described as being configured to pass water through it as a cooling medium, but a cooling medium other than water, such as a fluorine-based inert liquid, can also be used.

In the first embodiment, the cooling water C2 discharged from the outlet 12q is configured to be returned to the supply mechanism 15, but it may also be configured to be discharged directly to the outside of the light irradiation device 1.

Figure 4 shows the cooling member 12z as seen from the +Z side, and although not actually visible, an example of the flow paths (12c, 12d) formed on the inside through which the cooling water C1 flows is shown by dashed lines. The flow path 12c is configured to connect the inlet 12p to the outlet 12q in the order of the first area A1, the second area A2, and the third area A3, and a bypass flow path 12d is formed in part of the third area A3 to connect the first area A1 to the second area A2.

In the first embodiment, as shown in FIG. 1, the supply mechanism 15 is connected to the inlet 12p and the outlet 12q by the water distribution pipe 15a, but instead of the water distribution pipe 15a, a water distribution plate in which a water distribution channel is formed may be provided. The water distribution plate does not require as much space as the water distribution pipe 15a, so the entire light irradiation device 1 can be made smaller.

The main component of the material of the LED substrate 12 on which the LED elements 11 are mounted is ceramics such as metal oxides and metal nitrides, which are insulating materials, and aluminum nitride and silicon nitride, which have high thermal conductivity, are particularly preferable.

As shown in FIG. 4, the flow path 12c connects the inlet 12p to the outlet 12q so that the air passes from the inlet 12p through the first area A1, the second area A2, and the third area A3 of the LED substrate 12 in that order.

Furthermore, the flow paths 12c are formed to connect a specific inlet 12p and outlet 12q, and each flow path 12c is configured to be point symmetrical with respect to the center of the LED substrate 12.

For example, if the flow path 12c is formed so as to go around the peripheral edge of the cooling member 12z in the circumferential direction, the cooling water C1 absorbs heat as it flows and the temperature gradually increases. This causes a temperature gradient in the circumferential direction of the LED board 12.

With the above configuration, cooling water C1 is fed from the supply mechanism 15 into each inlet 12p, and the LED board 12 is cooled point-symmetrically. This reduces the temperature gradient in the circumferential direction of the LED board 12 compared to when the flow path 12c is formed to go around the peripheral end. This reduces temperature unevenness across the entire LED board 12.

The above configuration described with reference to Figures 1 and 2 suppresses a decrease in the intensity of light irradiated to the peripheral end W1e of the main surface W1a of the substrate W1 to be processed, without increasing the size of the chamber 10 or the LED substrate 12. In this way, the difference between the intensity of light irradiated to the center portion W1c and the intensity of light irradiated to the peripheral end W1e is reduced.

In addition, the region W1d between the central portion W1c and the peripheral end portion W1e is irradiated with low-luminance light from the third region A3, which has a low density of LED elements 11, improving the uniformity of the light intensity distribution across the entire main surface W1a of the substrate W1 to be processed compared to conventional methods.

Furthermore, by adopting the cooling configuration described with reference to Figure 4, the temperature distribution across the entire LED substrate 12 can be made more uniform.

Therefore, the uniformity of the light irradiated onto the substrate W1 to be processed is improved without increasing the size of the light irradiation device 1.

Figure 5 is a graph showing an example of the relative intensity of light irradiated onto the main surface W1a of the substrate W1 to be processed in each configuration. The graph shown in Figure 5 is a graph of the relative intensity to the light intensity at the center (0 mm) of the substrate W1 to be processed when light is irradiated onto the substrate W1 to be processed having a diameter of 300 mm from each LED board 12 designed with different arrangements of the LED elements 11 as described below. Note that when calculating the relative intensity, the distance in the Z direction between the substrate W1 to be processed and the LED board 12 was set to 60 mm, but it is preferable that the distance be set in the range of 45 mm to 80 mm.

L1 is the calculation result for a configuration in which the LED elements 11 are arranged at approximately equal intervals across the entire LED board 12. L2 is the calculation result for a configuration in which the LED elements 11 are arranged at a high density only in areas that are 30 mm or more away from the center of the LED board 12. L3 is the calculation result for a configuration that differs from the configuration shown in Figures 1 and 2 in some areas, but meets the conditions of the first embodiment described above.

In a configuration in which the LED elements 11 are arranged at approximately equal intervals across the entire LED substrate 12, as shown by L1 in Figure 5, the intensity is significantly reduced on the peripheral edge W1e side (distance from the center 100 mm or more) compared to the central portion W1c side (distance from the center 100 mm or less) of the substrate W1 to be processed, and at a position 150 mm away from the center, the light intensity is reduced to 50% or less compared to the central portion.

In a configuration in which the LED elements 11 are densely arranged only in areas 30 mm or more away from the center of the LED board 12, as shown by L2 in FIG. 5, the light intensity is higher in the area where the light emitted from the LED elements 11 arranged in the first area A1 overlaps with the light emitted from the LED elements 11 arranged in the second area A2 than in other areas. This is thought to be due to the occurrence of an area where the light emitted from the LED elements 11 arranged on the central portion W1c side overlaps with the light emitted from the LED elements 11 arranged at a high density on the peripheral edge W1e side.

According to the configuration of the first embodiment, as shown by L3 in FIG. 5, a large decrease in light intensity at the peripheral edge (100 mm or more away from the center) of the substrate W1 to be processed is suppressed, and no region occurs where the relative intensity to the light intensity at the center exceeds 1.1 at any position. This is thought to be because the light emitted from the region (first region A1) where the LED elements 11 are densely arranged on the peripheral edge W1e side overlaps with the light emitted from the region (third region A3) where the LED elements 11 are less densely arranged than on the central portion W1c side, resulting in a lower light intensity in total than the region (second region A2) on the central portion W1c side.

As shown by L3 in FIG. 5, the decrease in light intensity at a distance of 150 mm from the center is an improvement over L1, which is the result of the conventional configuration, but is still below 80% of the light intensity at the center. Therefore, in order to bring the light intensity at the peripheral edge closer to the light intensity at the center, it is possible to consider, for example, providing a mirror that reflects the light irradiated to the outside of the substrate W1 to be processed toward the main surface W1a of the substrate W1 to be processed.

Figure 6 is a cross-sectional view of another configuration of the first embodiment of the light irradiation device 1 when viewed in the Y direction. As shown in Figure 6, the light irradiation device 1 may be equipped with a mirror 70 that reflects light traveling to the outside of the substrate W1 to be processed toward the main surface W1a of the substrate W1 to be processed. By providing the mirror 70, the intensity of the light irradiated to the peripheral edge W1e of the substrate W1 to be processed is increased, the decrease in light intensity at the peripheral edge (distance from the center 100 mm or more) of the graph L3 shown in Figure 5 is suppressed, and the uniformity of the intensity of the light irradiated to the main surface W1a of the substrate W1 to be processed is further improved.

In the first embodiment, the mirror 70 is arranged so that the reflecting surface 70a is parallel to the Z axis as shown in FIG. 6, but the reflecting surface 70a may be arranged so that it is tilted with respect to the Z axis.

In the light irradiation device 1 of the first embodiment, for example, if the luminance of each area (A1, A2, A3) can be configured to satisfy the relationship of first area A1>second area A2>third area A3 by adjusting the power supplied to each area (A1, A2, A3), the arrangement density of each area (A1, A2, A3) does not have to be configured to satisfy the relationship of first area A1>second area A2>third area A3.

In the first embodiment, the LED board 12 is configured to have three regions: the first region A1, the second region A2, and the third region A3. However, the LED board 12 may be configured to be divided into four or more regions. In addition, there may be other regions between the first region A1 and the third region A3, and between the second region A2 and the third region A3.

[Second embodiment]
The configuration of the second embodiment of the light irradiation device 1 of the present invention will be described, focusing on the differences from the first embodiment.

Figure 7 is a cross-sectional view that shows a schematic configuration of a second embodiment of the light irradiation device 1. As shown in Figure 7, in the second embodiment of the light irradiation device 1, the LED board 12 is configured by combining multiple small boards 12n. Figure 7 shows, as an example, a form in which the LED board 12 is configured by nine small boards 12n.

Due to manufacturing or characteristics issues, it may not be possible to produce an LED substrate 12 of the same size as the substrate W1 to be processed from a single sheet of material, for example because large substrates are not manufactured and sold.

Therefore, as shown in FIG. 7, the LED substrate 12 is configured by combining multiple small substrates 12n, so that even in the above case, the light irradiation device 1 can be configured to match the size of the substrate W1 to be processed.

Figure 8 is a drawing of the cooling member 12z as seen from the +Z side, and like Figure 4, an example of a flow path (12c, 12d) formed on the inside through which the cooling water C1 flows is shown by dashed lines, although it is not actually visible.

The flow path 12c of the cooling water C1 in the second embodiment will be described below using some of the small substrates 12n. In the second embodiment, as shown in FIG. 1, the cooling water C1 is introduced from the supply mechanism 15 into an inlet 12p provided in the cooling member 12z. The cooling water C1 (not shown) then flows through the flow path 12c in the first area A1 shown in FIG. 8. In the second embodiment, each small substrate 12n is provided with a cooling member 12z that has the same shape when viewed from the Z direction.

The cooling water C1 that flows through the flow path 12c in the first area A1 of the cooling member 12z flows through the bypass flow path 12d and then through the flow path 12c in the second area A2.

The cooling water C1 that flows through the flow path 12c in the second area A2 flows into a connection port 12s that is connected to a water distribution pipe (not shown), and flows through the water distribution pipe into the connection port 12s of the small central substrate 12n.

The cooling water C1 that flows into the connection port 12s of the small substrate 12n flows through the flow path 12c formed in the central cooling member 12z and flows into another connection port 12s of the cooling member 12z.

The cooling water C1 discharged from the connection port 12s of the central cooling member 12z flows through a water distribution pipe into the connection port 12s provided in the third area A3 of the original cooling member 12z.

The cooling water C1 that flows into the connecting port 12s provided in the third area A3 of the original cooling member 12z flows through the flow path 12c formed in the third area A3, and is finally discharged as cooling water C2 (not shown) from the discharge port 12q.

In this way, the cooling water C1 flows from the inlet 12p through the first area A1, the second area A2, and the third area A3 in that order, and is distributed from the outlet 12q. Note that the above configuration is merely an example, and the flow path 12c may have a different configuration from the above configuration.

[Another embodiment]
Another embodiment will be described below.

<1> The light irradiation device 1 may be equipped with an optical system such as a lens, a prism, a diffusion plate, or an integrator optical system so that the light emitted from the LED element 11 is evenly irradiated onto the entire main surface W1b of the substrate W1 to be processed.

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

LIST OF SYMBOLS 1: Light irradiation device 10: Chamber 10a: Light-transmitting window 11: LED element 12: LED substrate 12a: Observation hole 12c: Flow path 12d: Bypass flow path 12n: Small substrate 12p: Inlet 12q: Outlet 12s: Connection port 12z: Cooling member 13: Support member 14: Radiation thermometer 15: Supply mechanism 15a: Water distribution pipe 15b: Water distribution channel 15p: Water distribution plate 70: Mirror 70a: Reflecting surface 100: Light irradiation device 101: Chamber 101a: Light-transmitting window 102: LED element 103: LED substrate 104: Support member A1, A2, A3: Area C1, C2: Cooling water W1: Substrate to be processed W1a: Main surface W1c: Center part W1d: Area W1e: Peripheral end part

Claims (5)

A light irradiation device that irradiates a substrate to be processed with light,
a chamber having a light-transmitting window for accommodating the substrate to be processed;
a support member for supporting the substrate to be processed within the chamber;
an LED substrate disposed outside the chamber so as to face the substrate supported by the support member across the light-transmitting window;
a plurality of LED elements arranged on a main surface of the LED substrate so as to emit light toward a main surface of the substrate supported by the support member ;
a cooling member having an inlet for introducing a cooling medium for cooling the LED elements, an outlet for discharging the cooling medium to the outside of the LED substrate, and a flow path connecting the inlet and the outlet, the cooling member being provided on a surface of the LED substrate opposite to a surface on which the LED elements are mounted;
a supply mechanism that supplies the cooling medium from the inlet of the LED substrate into the flow path ,
When the region of the LED substrate in which the LED elements are arranged is divided into a plurality of concentric regions, the plurality of regions are:
An outermost first region;
a second region, which is a region inside the first region and separated from the first region, and in which a value obtained by dividing a total value of the supplied power by an area in which the LED elements are mounted is smaller than that of the first region;
a third region, the third region being sandwiched between the first region and the second region, in which a value obtained by dividing a total value of supplied power by an area in which the LED elements are mounted is smaller than that of the second region ;
A light irradiation device , characterized in that the flow path of the cooling member passes from the inlet through the first region, the second region, and the third region of the LED substrate in that order . the number of the LED elements per unit area in the second region is smaller than the number of the LED elements per unit area in the first region;
2 . The light irradiation device according to claim 1 , wherein the number of the plurality of LED elements per unit area in the third region is smaller than the number of the plurality of LED elements per unit area in the second region. 3. The light irradiation device according to claim 1, wherein the LED substrate is made of a material whose main component is aluminum nitride or silicon nitride. 4. The light irradiation device according to claim 1, wherein the LED substrate has a hole connecting the main surfaces of the LED substrate. 5. The light irradiation device according to claim 1, wherein a main emission wavelength of the LED element is within a range of 300 nm to 1050 nm.