JP6900639B2 - Light source unit - Google Patents

Description

The present invention relates to a light source unit for heat-treating the object to be processed by, for example, irradiating the object to be processed with light, and particularly to a light source unit provided with a large number of LED elements as a light source.

As a method of heat-treating the object to be processed performed in various processes of the semiconductor manufacturing process, for example, a method of heating the object to be processed by light irradiation (non-contact method by light heating) is known. As a light source in the light heat treatment, for example, a discharge lamp such as a flash lamp has been used, but in recent years, a light heat treatment technique using an LED as a light source has been put into practical use.
For example, Patent Document 1 describes a liquid treatment apparatus for wet cleaning the surface of a semiconductor wafer, which comprises an LED for radiating light in a wavelength region absorbed only by the semiconductor wafer to heat the semiconductor wafer. ..

Japanese Patent No. 5254308

In a single-wafer processing apparatus, in order to perform light heat treatment on an object to be processed such as a semiconductor wafer, it is necessary to deploy a light source facing the object to be processed. It is desirable that the light source is arranged on the lower surface side of the object to be processed for the convenience of device design. It is restricted. Therefore, in the light heat treatment using LEDs, the actual situation is that the size of the LED arrangement area must be set smaller than the diameter of the object to be processed. Therefore, it is difficult to uniformly irradiate the peripheral portion of the object to be treated with light, and there is a problem that the object to be processed cannot be heated in a state of high temperature uniformity over the entire surface.
Assuming that a light source capable of uniformly irradiating the entire surface of the object to be processed is provided on the upper surface side of the object to be processed, light is emitted to the surface other than the object to be processed. Damage and increased temperature will impair the uniformity of the heat treatment.

The present invention has been made based on the above circumstances, and can uniformly irradiate a wide range of light without setting a large size of a light source arrangement area in which a large number of LED elements are arranged. It is an object of the present invention to provide a light source unit capable of providing a light source unit.

The light source unit of the present invention includes a light source unit in which a large number of LED elements are arranged, and a translucent protective cover provided so as to cover a light source arrangement area in the light source unit in which the large number of LED elements are arranged. And
The translucent protective cover has an optical element portion that refracts the light from the LED element outward on the peripheral portion thereof.
The translucent protective cover serves as the optical element portion formed on a plate-shaped base portion extending in parallel with the LED element arrangement surface on which a large number of LED elements are arranged and a peripheral edge portion on one surface of the base portion. It is composed of a frame portion that surrounds the functioning light source arrangement area.
The frame portion has an outer surface along one surface of the base portion, and the inner peripheral surface of the frame portion facing the light source arrangement region becomes the LED element arrangement surface as it goes outward in the radial direction of the light source arrangement region. It is formed by an inclined surface that inclines in the approaching direction.
In the translucent protective cover, the base portion extends in a direction orthogonal to the optical axes of the plurality of LED elements, and the optical axes of some of the LED elements constituting the light source portion extend toward the inclined surface of the base. It is characterized in that it is arranged in a state of extending perpendicularly to the outer surface of the frame portion along one surface of the portion.

In the light source unit of the present invention, it is preferable that the frame portion of the translucent protective cover has a side surface extending perpendicularly to the LED element mounting surface .

In the light source unit having such a configuration, the inclined surface forming the inner peripheral surface of the frame portion of the translucent protective cover is configured to be continuous with one surface of the base portion via the curved surface. Is preferable.

Furthermore, it is preferable that the light source unit of the present invention is configured to be used for heat treatment of an object to be treated, which is arranged apart from the other surface of the substrate portion in the translucent protective cover.

According to the light source unit of the present invention, the light rays incident on the optical element portion can be emitted with directivity by the action of the optical element portion in the translucent protective cover, so that the light rays can be emitted from the light source portion. Light can be uniformly irradiated over a wide range.

It is sectional drawing which shows schematic structure in the example of the light source unit of this invention. It is a top view which shows roughly the structure in an example of a light source part. It is explanatory drawing which shows typically the ray tracing line of the light emitted from the LED element arranged in the state that the optical axis extends toward the inclined surface. It is sectional drawing which shows a part of the structure in the light source unit which concerns on a reference example, together with a ray tracing line. The test wafer was light-heated by each of the light source units according to Experimental Example 1 and Reference Experimental Example 1, and the temperature distribution on the light-irradiated surface of the test wafer when the temperature at the center of the test wafer reached 100 ° C. It is a figure which shows. Only two LED elements, one LED element related to the LED row located on the outermost radial edge side of the light source unit according to Experimental Example 1 and one LED element in the inner LED row adjacent to the LED element in the radial direction are lit. It is a figure which shows the illuminance distribution on the light irradiation surface of the test wafer when it was made. Only two LED elements in the LED row located on the outermost radial edge side of the light source unit according to Reference Experimental Example 1 and one LED element in the LED row on the inner side in the radial direction adjacent to the LED element are used. It is a figure which shows the illuminance distribution on the light irradiation surface of the test wafer when it is turned on. Only two LED elements in the LED row located on the outermost radial edge side of the light source unit according to Reference Experimental Example 2 and one LED element in the LED row on the inner side in the radial direction adjacent to the LED element are used. It is a figure which shows the illuminance distribution on the light irradiation surface of the test wafer when it is turned on.

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 is a cross-sectional view schematically showing a configuration in an example of the light source unit of the present invention. FIG. 2 is a plan view schematically showing the configuration of an example of the light source unit.
The light source unit 10 is a translucent protective cover provided so as to cover a light source unit 15 in which a large number of LED elements 11 are arranged and a light source arrangement area R in which a large number of LED elements 11 are arranged in the light source unit 15. It is equipped with 20.

The light source unit 15 in the illustrated example is configured such that, for example, a large number of LED elements 11 are arranged concentrically with the peripheral edge of the light source arrangement area R in the circular light source arrangement area R on one surface of the disk-shaped substrate 13. Has been done. Specifically, a plurality of annular LED rows 12 in which a plurality of LED elements 11 are arranged along the circumference of a circle C centered on the optical axis of the LED element 11 arranged at the center position of the light source arrangement region R. They are arranged concentrically.

As the LED element 11, one that radiates visible light, one that radiates ultraviolet rays, and one that radiates infrared rays can be selected and used depending on the purpose and application.
The form of the LED element 11 is not particularly limited, and may be a surface mount type or package type LED element, an LED chip, a lens-integrated LED element, a bullet-type LED element, or the like. As the LED element 11 in this example, for example, a surface mount type rectangular LED element 11 is used.
The arrangement pitch (distance between the optical axes L) of the two adjacent LED elements 11 is substantially the same. The optical axis L of the LED element 11 means the central axis of light radiated from the LED element 11, and in the illustrated example, the axis passing through the center of the light emitting surface is the optical axis L.

The translucent protective cover 20 has an optical element portion that refracts the light from the LED element 11 outward on the peripheral portion thereof. Specifically, the optical element unit has a function of emitting light incident on the optical element unit with directivity.

The translucent protective cover 20 in the illustrated example is a disk-shaped base portion 21 extending in parallel with the LED element arrangement surface S on which a large number of LED elements 11 are arranged, and one surface (inner surface) 21a of the base portion 21. It is composed of a frame portion 22 that surrounds the periphery of the light source arrangement region R formed on the peripheral edge portion, and the frame portion 22 functions as an optical element portion.

The inner peripheral surface of the frame portion 22 facing the light source arrangement region R is formed by an inclined surface 22a that inclines in a direction approaching the LED element arrangement surface S as it goes outward in the radial direction of the light source arrangement area R. The translucent protective cover 20 is arranged in a state in which the optical axis L of at least a part of the LED elements 11 constituting the light source portion 15 extends toward the inclined surface 22a forming the inner peripheral surface of the frame portion 22. ing. With such a configuration, the light from the light source unit 15 can be uniformly irradiated over a wide range.

Further, it is preferable that the inclined surface 22a forming the inner peripheral surface of the frame portion 22 is continuous with the inner surface 21a of the base portion 21 via the curved surface 23. If the inclined surface 22a forming the inner peripheral surface of the frame portion 22 is connected to the inner surface 21a of the base portion 21 without passing through the curved surface 23, the refraction direction of light is different between the frame portion 22 and the base portion 21. Because of the change, there is a drop in illuminance (see FIG. 8). Therefore, the inclined surface 22a forming the inner peripheral surface of the frame portion 22 is configured to be continuous with the inner surface 21a of the base portion 21 via the curved surface 23, so that the illuminance does not drop and is widespread. It is possible to irradiate the light uniformly over the entire area.

The material constituting the translucent protective cover 20 can be selected according to the purpose and application, but a translucent glass material or a translucent resin material can be used. Examples of such glass materials include quartz and borosilicate glass. Further, as the resin material, for example, a fluororesin such as PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) and FEP (perfluoroethylene propene copolymer) can be exemplified.
When the light source unit 10 is used, for example, in a heat treatment (drying treatment) performed on an object to be processed in a wet cleaning treatment in a semiconductor manufacturing process, it has high chemical resistance and thus protects light transmission. As the material constituting the cover 20, it is preferable to use PFA, FEP, or a glass coated with these fluororesins.

The inclination angle of the inclined surface 22a forming the inner peripheral surface of the frame portion 22 with respect to the LED element arrangement surface S is preferably in the range of, for example, 40 to 50 °.

Thus, when the light source unit 10 is configured to be used for heat treatment of a plate-shaped object W such as a semiconductor wafer, the light source unit 10 is, for example, the object W to be processed. The other surface (outer surface) 21b of the base portion 21 of the translucent protective cover 20 is arranged on the lower side of the surface so as to be separated from the object W to be processed. In such a case, usually, the LED row 12 located on the outermost edge side in the radial direction of the light source unit 15 must be arranged at a position on the inner side of the outer peripheral edge position of the object W to be processed by about 10 mm in the radial direction. The reality is that you don't get it.
However, in the light source unit 10 described above, the translucent protective cover 20 provided so as to cover the light source arrangement region R functions as an optical element portion that refracts the light from the LED element 11 outward. The frame portion 22 formed by the inclined surface 22a is provided. Then, the light-transmitting protective cover 20 is the optical axis L of at least a part of the LED elements 11 constituting the light source unit 15, specifically, the LED element 11a related to the LED row 12 located on the outermost edge side in the radial direction. Is arranged so as to extend toward the inclined surface 22a. Therefore, according to the light source unit 10 described above, the light rays incident on the frame portion 22 of the translucent protective cover 20 can be directed toward the peripheral edge portion of the object W to be processed.

That is, as shown in FIG. 3, for example, most of the light emitted from the LED element 11a related to the LED row 12 located on the outermost edge side in the radial direction of the light source arrangement region R is an inclined surface of the translucent protective cover 20. It will be incident on 22a or the curved surface 23.
Of the light rays (light components) radiated outward in the radial direction with respect to the optical axis L of the LED element 11a, the light rays radiated along the normal direction of the inclined surface 22a of the translucent protective cover 20. Light rays emitted at a larger radiation angle are refracted inward in the radial direction with respect to the incident direction of the light rays by the inclined surface 22a of the translucent protective cover 20. On the other hand, the light rays (including the light rays radiated in the optical axis direction) emitted from the LED element 11 at a radiation angle smaller than the light rays radiated from the LED element 11 along the normal direction of the inclined surface 22a of the translucent protective cover 20. , The incident direction with respect to the inclined surface 22a changes. Therefore, the light beam is refracted radially outward with respect to the incident direction of the light beam by the inclined surface 22a of the translucent protective cover 20.
Further, the light rays radiated inward in the radial direction with respect to the optical axis L of the LED element 11a are refracted outward in the radial direction with respect to the incident direction. However, the light beam incident on the inclined surface 22a of the translucent protective cover 20 is refracted radially outward with respect to the normal direction of the outer surface 21b of the translucent protective cover 20, whereas it is transparent. The light rays incident on the curved surface 23 of the light-transmitting protective cover 20 are refracted inward in the radial direction with respect to the normal direction of the outer surface 21b of the light-transmitting protective cover 20. However, the difference in the refraction angle of the light rays incident near the boundary between the inclined surface 22a and the curved surface 23 is small between the case where the light rays are incident on the inclined surface 22a and the case where the light rays are incident on the curved surface 23. Therefore, the direction of refraction differs depending on whether the light is refracted by the inclined surface 22a or the curved surface 23, but the spread of the light rays traveling through the translucent protective cover 20 is suppressed to be small. Become.

Then, the light traveling toward the outer peripheral surface of the translucent protective cover 20 is refracted and emitted inward in the radial direction with respect to the incident direction on the outer peripheral surface of the translucent protective cover 20. Further, the light refracted by the inclined surface 22a of the translucent protective cover 20 and traveling toward the outer surface 21b of the translucent protective cover 20 has a diameter with respect to the incident direction on the outer surface 21b of the translucent protective cover 20. It is refracted outward in the direction and emitted. Furthermore, the light refracted by the curved surface 23 of the translucent protective cover 20 and traveling toward the outer surface 21b of the translucent protective cover 20 is directed toward the incident direction on the outer surface 21b of the translucent protective cover 20. It is refracted inward in the radial direction and emitted.

On the other hand, as shown in FIG. 4, it is assumed that a translucent protective cover 20a having a cylindrical frame portion 25 whose inner peripheral surface 25a extends perpendicularly to the LED element arrangement surface S is used. In the light source unit 10a having such a configuration, the light rays radiated toward the frame portion 25 of the translucent protective cover 20a are refracted radially outward with respect to the incident direction of the light rays. Then, on the outer peripheral surface of the translucent protective cover 20a, it is refracted inward in the radial direction with respect to the incident direction and emitted. On the other hand, among the light rays emitted toward the base portion 21 of the translucent protective cover 20a, the light rays directed outward in the radial direction with respect to the optical axis of the LED element 11a are the inner surfaces 21a of the base portion 21. Is refracted inward in the radial direction with respect to the incident direction. Then, the light beam is refracted and emitted outward in the radial direction with respect to the incident direction on the outer surface 21b of the translucent protective cover 20.
Of the light rays radiated toward the base portion 21 of the translucent protective cover 20a, the light rays directed inward in the radial direction with respect to the optical axis of the LED element 11a are incident on the inner surface 21a of the base portion 21. It is refracted radially outward with respect to the direction. Then, the light beam is refracted inward in the radial direction with respect to the incident direction on the outer surface 21b of the translucent protective cover 20a and emitted.

As described above, in the light source unit 10a having the configuration shown in FIG. 4, the light rays emitted from the LED element 11a are refracted by the inner peripheral surface 25a of the frame portion 25 and by the inner surface 21a of the base portion 21. The direction of refraction differs from case to case. Therefore, the light beam incident on the vicinity of the boundary portion between the inner peripheral surface 25a of the frame portion and the inner surface 21a of the base portion 21 is transparent depending on whether the light beam is incident on the frame portion 25 or the base portion 21. The traveling directions in the optical protective cover 20a are significantly different, and as a result, the uniformity of illuminance on the light-irradiated surface of the object W to be processed becomes low.

However, according to the light source unit 10 having the configuration shown in FIG. 3, by controlling the light distribution of the LED element 11a, the light from the LED element 11a can be selectively irradiated to the peripheral edge portion of the object W to be processed. Therefore, as shown in the results of the experimental examples described later, the light from the light source unit 15 can be uniformly irradiated over a wide range without setting the light source arrangement region R large. Therefore, according to the above-mentioned light source unit 10, the object W to be processed can be heated in a state of high temperature uniformity over the entire surface.

Although one embodiment of the light source unit of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made.
For example, the inner peripheral surface of the frame portion that functions as the optical element portion in the translucent protective cover may be formed by an arc-curved curved surface in a cross section perpendicular to the base portion. Further, the inner peripheral surface of the frame portion may be composed of a surface including a Fresnel surface.
Further, the light source unit does not have to have a configuration in which all the LED elements are arranged on the same plane. Furthermore, the light source unit is not limited to the configuration according to the above embodiment, and a large number of LED elements are arranged in the light source arrangement region R having an annular shape or a partial annular shape (for example, a peripheral portion of an object to be processed). It may be configured to lightly heat only the light source).

Hereinafter, an example of an experiment conducted to confirm the effect of the present invention will be described.

[Experimental Example 1]
The light source unit according to the present invention was manufactured according to the configurations shown in FIGS. 1 and 2. The specifications of this light source unit are as shown below.
<Light source unit (15)>
Light source arrangement area (R): Circular LED element (11 (11a)) having a diameter of 292 mm Center emission wavelength: 850 nm, size: 1.0 mm square, output: 1.0 W, arrangement pitch: 1.5 mm
<Translucent protective cover (20)>
Material: PFA (refractive index = 1.3), outer diameter dimension: φ300 mm, height direction dimension: 5 mm, inclination angle of the inner peripheral surface of the frame (inclined surface 22a) with respect to the light source arrangement surface (S): 45 °, curved Radiation of curvature of the surface (23): 3 mm, radial distance between the inner peripheral edge position on the open end surface of the frame portion and the optical axis position of the LED element (11a) related to the LED row (12) located on the outermost edge side in the radial direction. Distance: 2.5 mm, thickness of substrate (21): 2 mm

A test wafer (W) having a diameter of 300 mm is placed at a position 5 mm away from the outer surface (21b) of the substrate portion (21) in the translucent protective cover (20) of the light source unit produced above, and the shape center position of the test wafer (W) is the light source unit (21b). It was arranged so as to extend parallel to the outer surface (21b) of the substrate portion (21) in a state of matching the center position of 10). Further, thermocouples were laid on the surface of the test wafer (W) at a pitch of about 30 mm in the radial direction.
Then, the LED elements (11) in the light source unit (10) are turned on all at once, and the light irradiation surface of the test wafer (W) when the temperature of the central portion of the test wafer (W) reaches 100 ° C. The temperature distribution in. The results are shown by curves (α, circled plots) in FIG. The position of "0" mm on the horizontal axis of FIG. 5 is the center position of the test wafer (W).
Further, only two LED elements (11a) related to the LED row (12) located on the outermost edge side in the radial direction and one LED element in the LED row on the inner side in the radial direction adjacent to the LED element (11a). Was turned on, and the illuminance distribution of the test wafer (W) on the light irradiation surface was measured. The results are shown in FIG. The position of "0" mm on the horizontal axis of FIG. 6 is the peripheral position of the test wafer (W), and the position of "8" mm is the position of the optical axis of the LED element (11a).

[Reference Experiment Example 1]
Experiments except that the translucent protective cover (20a) has a cylindrical shape as a whole in which the inner peripheral surface (25a) of the frame portion (25) extends perpendicularly to the LED element arrangement surface (S). A light source unit (10a, see FIG. 4) having the same configuration as the light source unit in Example 1 was produced.
Then, the temperature distribution on the light-irradiated surface of the test wafer (W) was examined by the same method as in Experimental Example 1. The results are shown in FIG. 5 as a curve (β, plot of diamond marks).
Further, the illuminance distribution on the light irradiation surface of the test wafer (W) was measured by the same method as in Experimental Example 1. The results are shown in FIG.

[Experimental Example 2]
The light source in Experimental Example 1 except that the inner surface (21a) of the base portion (21) and the inner peripheral surface (22a) of the frame portion (22) are connected without a curved surface. A light source unit having the same configuration as the unit was manufactured.
Then, the illuminance distribution on the light irradiation surface of the test wafer (W) was measured by the same method as in Experimental Example 1. The results are shown in FIG.

As is clear from the above results, according to the light source unit according to Experimental Example 1, the temperature on the light irradiation surface of the test wafer up to the position of the measurement point on the outermost edge side of the test wafer (position 145 mm from the center). It was confirmed that the light heat treatment with high in-plane uniformity can be performed.
Further, in the light source unit according to Experimental Example 2, it was confirmed that the temperature at the position of the measurement point on the outermost edge side of the test wafer was slightly lower than that of the light source unit according to Experimental Example 1. It is presumed that the reason for this is that, as shown in FIG. 8, an illuminance drop portion occurs in the illuminance distribution.
In the light source unit according to Reference Experimental Example 1, the temperature at the measurement point on the outermost edge side of the light irradiation surface of the test wafer is about 15 ° C. lower than the temperature inside. It was confirmed that.

10 Light source unit 10a Light source unit 11 LED element 11a LED element 12 LED row 13 Substrate 15 Light source unit 20 Translucent protective cover 20a Translucent protective cover 21 Base unit 21a One side (inner surface)
21b Other surface (outer surface)
22 Frame part 22a Inclined surface 23 Curved surface 25 Frame part 25a Inner peripheral surface C Circle L Optical axis R Light source arrangement area S LED element arrangement surface W Processed object

Claims (4)

It is provided with a light source unit in which a large number of LED elements are arranged and a translucent protective cover provided so as to cover the light source arrangement area in which the large number of LED elements are arranged.
The translucent protective cover has an optical element portion that refracts the light from the LED element outward on the peripheral portion thereof.
The translucent protective cover serves as the optical element portion formed on a plate-shaped base portion extending in parallel with the LED element arrangement surface on which a large number of LED elements are arranged and a peripheral edge portion on one surface of the base portion. It is composed of a frame portion that surrounds the functioning light source arrangement area.
The frame portion has an outer surface along one surface of the base portion, and the inner peripheral surface of the frame portion facing the light source arrangement region becomes the LED element arrangement surface as it goes outward in the radial direction of the light source arrangement region. It is formed by an inclined surface that inclines in the approaching direction.
In the translucent protective cover, the base portion extends in a direction orthogonal to the optical axes of the plurality of LED elements, and the optical axes of some of the LED elements constituting the light source portion extend toward the inclined surface. A light source unit characterized in that it is arranged so as to extend perpendicularly to the outer surface of the frame portion along one surface of the portion. The light source unit according to claim 1, wherein the frame portion of the translucent protective cover has a side surface extending perpendicularly to the LED element mounting surface. The first or second aspect of the cover, wherein the inclined surface forming the inner peripheral surface of the frame portion of the translucent protective cover is continuous with one surface of the base portion via the curved surface. Light source unit. The light source unit according to any one of claims 1 to 3, wherein the light source unit is used for heat treatment of an object to be treated, which is arranged apart from the other surface of the substrate portion in the translucent protective cover.

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