OPTICAL HEATING METHOD, OPTICAL HEATING DEVICE FOR N-TYPE SiC SEMICONDUCTOR

Abstract

To provide an optical heating method that can efficiently heat a to-be-processed body containing n-type SiC semiconductors, and an optical heating device.SOLUTION: An optical heating method by an optical heating device 1 has a step for heating a to-be-processed body W1 by measuring the reflectance R and the transmittance T of n-type SiC, employing the method to derive the absorption coefficient A(=1-R-T) for each wavelength of the n-type SiC, and radiating heating light L1 with a peak wavelength in the range of 415 nm to 500 nm emitted from a light source section 2 through a window member 10b on to the to-be-processed body containing the n-type SiC semiconductor.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an optical heating method, and more particularly to an optical heating method for a workpiece including an n-type SiC semiconductor.The present invention also relates to an optical heating device for an n-type SiC semiconductor. [Background technology]

[0002] In the semiconductor manufacturing process, various heat treatments such as film formation, oxidation and diffusion, modification, and annealing are performed on objects to be treated, including semiconductor wafers. Light is often used in carrying out these heat treatments. Heating an object to be treated using light in this manner is called "light heating." Furthermore, light used for heating is called "heating light."

[0003] A known example of a semiconductor heating device that utilizes optical heating is the technology described in the following Patent Document 1. The device in Patent Document 1 uses an LED lamp that emits heating light with a wavelength of 810 nm to 980 nm as a light source. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-009927 A [Non-patent literature]

[0005] [Non-Patent Document 1] "Polymer Materials Technology for Photoresist Materials" Akimasa Seiyano Journal of the Society of Rubber Science and Technology of Japan Vol. 85 No. 2 (2012) p.33~p.39 Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, the development of power semiconductor devices that can handle higher voltages and currents than conventional devices has progressed. For this reason, while conventional devices generally use Si, the use of SiC is being considered for recent devices in order to realize small devices that exhibit high voltage resistance. SiC is classified into n-type SiC, which has a relatively low resistivity, and semi-insulating SiC (sometimes called "semi-insulating SiC"), which has a relatively high resistivity. N-type SiC in particular has attracted attention due to its wide range of uses.

[0007] Generally known examples of n-type SiC include SiC doped with nitrogen (N) as a dopant, and generally known semi-insulating SiC include SiC doped with vanadium (V) as a dopant or SiC with lattice defects intentionally formed therein.

[0008] SiC has a larger band gap than conventional Si, and has a high dielectric breakdown field strength, and is expected to reduce environmental impact through low loss, small size, and weight. However, SiC transmits most of the light emitted from an LED lamp as described in Patent Document 1, and there is a problem that it cannot be heated efficiently. Note that Patent Document 1 does not particularly consider the case where a SiC wafer is used as the heating object. For this reason, Patent Document 1 does not mention at all that there is a wavelength range of light suitable for heat-treating a SiC wafer.

[0009] In view of the above problems, the present invention aims to provide an optical heating method capable of efficiently heating a workpiece containing an n-type SiC semiconductor, and also aims to provide an optical heating device suitable for heating a workpiece containing an n-type SiC semiconductor. [Means for solving the problem]

[0010] The light heating method according to the present invention comprises the steps of: The method is characterized by comprising a step (a) of heating a workpiece including an n-type SiC semiconductor by irradiating the workpiece through a window member with heating light having a peak wavelength in the range of 415 nm to 500 nm emitted from a light source.

[0011] In the above light heating method, The heating light preferably has a peak wavelength within a range of 420 nm to 490 nm.

[0012] The present inventors have been thoroughly investigating methods for heating objects containing SiC and have discovered the following. SiC comes in a variety of types, including 4H-SiC (band gap 3.3 eV), 6H-SiC (band gap 3 eV), and 3C-SiC (band gap 2.2 eV), depending on the crystal structure. In the case of 6H-SiC, which has a band gap of 3 eV, the transmittance of light gradually increases in the wavelength range longer than about 420 nm, and almost all light in the wavelength range longer than 500 nm is transmitted.

[0013] As mentioned above, SiC is classified into n-type, semi-insulating type, etc. according to the dopant used. The absorption rate of SiC can change even when doped with a dopant. For this reason, there is no wavelength range that is recognized as suitable for photothermal treatment of SiC.

[0014] In light of the above background, the present inventors have investigated how to derive the absorptance for each wavelength of n-type SiC, which is particularly expected to be put to practical use, and how to find a wavelength band of light suitable for optically heating n-type SiC. At the time of filing this application, it was difficult to directly measure the absorption spectrum of n-type SiC, so the present inventors adopted a method of measuring the reflectance R and transmittance T of n-type SiC and deriving the absorptance A (=1-RT), thereby deriving the absorptance for each wavelength of n-type SiC.

[0015] Specifically, the reflectance R is measured and derived using an n-type SiC wafer, a light source whose intensity spectrum of emitted light is known, and a spectrophotometer arranged on the same side of the n-type SiC wafer as the light source, while the transmittance T is measured and derived using an n-type SiC wafer, a light source whose intensity spectrum of emitted light is known, and a spectrophotometer arranged on the opposite side of the n-type SiC wafer from the light source.

[0016] FIG. 1 is a graph showing the relationship between wavelength and absorptance in n-type SiC. The graph shown in FIG. 1 is a graph calculated based on reflectance characteristic data and transmittance characteristic data of n-type SiC measured by the above-mentioned method. According to FIG. 1, it is found that the absorptance for light having a wavelength in the range of 415 nm to 500 nm is 45% or more, which is higher than the absorptance for light having a wavelength longer than 500 nm. In other words, even when the workpiece includes n-type SiC, high heating efficiency is achieved by irradiating the workpiece with heating light having a peak wavelength in the range of 415 nm to 500 nm from the light source unit for heating.

[0017] It is also found that the absorptance is 50% or more in the wavelength range of 420 nm to 490 nm. In other words, even when the workpiece contains n-type SiC, higher heating efficiency is achieved by irradiating the workpiece with heating light having a peak wavelength in the range of 420 nm to 490 nm from the light source.

[0018] The window member is made of a material having a high transmittance to the heating light as described above. This transmittance is preferably 50% or more, more preferably 70% or more, and particularly preferably 80% or more. As the material for the window member, synthetic quartz, fused quartz, sapphire, magnesium fluoride (MgF2), calcium fluoride (CaF2), or barium fluoride (BaF2) is preferably used. By making the window member out of such a material, the heating light is not significantly absorbed in the window member, and the heating light from the light source can be efficiently used to heat the object to be treated.

[0019] Fig. 2 is a graph showing the tendency of the light absorbance characteristics of resins used in semiconductor photoresists, as shown in the above-mentioned Non-Patent Document 1. Resins used in semiconductor photoresists include novolac resin, methacrylic resin, and PHS resin. As shown in Fig. 2, these resins are characterized by showing relatively high absorbance for light with a wavelength of 300 nm or less, and in particular, novolac resin and PHS resin suddenly show high absorbance for light with a wavelength of 300 nm or less.

[0020] For example, when the object to be processed is a SiC substrate, the semiconductor photoresist is used as a photoresist mask when ion implantation is performed on the SiC substrate. For this reason, important indices for the resin used in the semiconductor photoresist include light transmittance, chemical resistance, and solubility in a developer, and the light transmittance is adjusted according to the spectrum of the light emitted from the light source.

[0021] However, as mentioned above, many of the resins used in semiconductor photoresists have high absorbance for light with wavelengths of 300 nm or less. For this reason, it is preferable that the light emitted from an LED element has a certain bandwidth, and that the peak wavelength of the heating light emitted is at least 370 nm or more in order to further reduce absorption by the resin. In other words, in the waveform shown in Figure 1, there is a wavelength band that shows a relatively high absorption rate at 390 nm or less, but since there is a concern that light in this wavelength band may be absorbed by the resin, it is preferable to use light in a wavelength band of 400 nm or more.

[0022] In the light heating method, heating light having a peak wavelength in the range of 420 nm to 490 nm, which is a wavelength range much shorter than that of the conventional method, is used. By using heating light in this wavelength range, even if the object to be treated contains a SiC semiconductor, the heating light can be absorbed by the object to be treated to an extent that can provide a heating effect. This allows the object to be heated without contact.

[0023] Furthermore, since the above-mentioned light heating method uses heating light having a peak wavelength in the range of 420 nm to 490 nm, the effect of absorption by semiconductor photoresist is reduced compared to the case where heating light having a peak wavelength in a shorter wavelength band is used.

[0024] The light heating method includes: During the execution of the step (a), a step (b) may be included in which a radiation thermometer having a sensitivity wavelength range of a predetermined wavelength range of 0.7 μm to 5 μm receives light emitted from the object to be treated, thereby measuring the temperature of the object to be treated.

[0025] It is known that semiconductor light-emitting elements, such as LED elements, emit light in a wavelength range (main emission wavelength range) that includes the peak wavelength and has a relatively high emission intensity, as well as light in a wavelength range longer than the main emission wavelength range and with a relatively low emission intensity. Although the emission intensity of this light on the long wavelength side is very low compared to the intensity of the main emission wavelength range, it shows an intensity slightly higher than the tail intensity when approximated by a Gaussian distribution. This light on the long wavelength side is light originating from defects or impurity levels in the active layer that inevitably occur during the manufacture of the semiconductor light-emitting element, and is called "deep light."

[0026] For example, when a light source with a peak wavelength in the range of 400 nm to 1000 nm is used as a heating light source, the wavelength range of the deep light emitted from this light source, which has a relatively high intensity, overlaps with the sensitivity wavelength range of the radiation thermometer. As a result, a part of the light from the heating light source is received by the radiation thermometer, which may cause an erroneous detection of the temperature of the workpiece.

[0027] A radiation thermometer with a sensitivity wavelength range of 0.7 μm to 5 μm allows more precise temperature adjustment since it can measure the temperature of the object to be treated from a relatively low temperature range of 200° C. to 500° C. From the viewpoint of detecting the temperature with high accuracy from the initial stage after heating of the object to be treated is started, the sensitivity wavelength range of the radiation thermometer is more preferably 0.8 μm to 4 μm, and particularly preferably 1 μm to 3 μm.

[0028] The upper limit of the sensitivity wavelength range of the radiation thermometer may be appropriately set according to the melting point of SiC contained in the workpiece, but this does not exclude the use of a radiation thermometer capable of measuring a temperature range higher than the melting point to measure the temperature of the workpiece.

[0029] The light heating device of the present invention is An optical heating device for n-type SiC semiconductors, A chamber that accommodates a workpiece including an n-type SiC semiconductor; a support member for supporting the workpiece in the chamber; A light source unit that emits heating light having a peak wavelength in the range of 415 nm to 500 nm; a window member through which the heating light emitted from the light source passes and which guides the light to the object to be treated.

[0030] The optical heating device described above can efficiently perform heating in a non-contact manner when processing n-type SiC semiconductors used in power semiconductor devices, which are expected to have a particularly wide range of uses.

[0031] In the above-mentioned light heating device, The light source unit includes a plurality of substrates on which a plurality of semiconductor light emitting elements are mounted, The plurality of substrates may be arranged in line symmetry, point symmetry, or rotational symmetry when viewed in the normal direction to the main surfaces of the substrates.

[0032] According to the above-mentioned configuration, the light intensity distribution on the object to be processed is homogenized, so that the object to be processed can be heated uniformly. Effect of the Invention

[0033] According to the present invention, an optical heating method capable of efficiently heating a workpiece including an n-type SiC semiconductor is realized. Also, according to the present invention, an optical heating device suitable for heating a workpiece including an n-type SiC semiconductor is realized. [Brief description of the drawings]

[0034] [Figure 1] 1 is a graph showing the relationship between wavelength and absorptance in n-type SiC. [Diagram 2] 1 is a graph showing the tendency of the light absorbance characteristics of a resin used in a semiconductor photoresist. [Diagram 3] FIG. 1 is a cross-sectional view showing a schematic configuration of an embodiment of a light heating device. [Figure 4] 1 is an example of the spectrum of heating light emitted from a light source unit and having a peak wavelength of 460 nm. [Diagram 5] FIG. 2 is a schematic plan view of the light source unit as viewed from the -Z side. [Figure 6] FIG. 2 is a plan view illustrating a schematic configuration of a substrate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] The optical heating method according to the present invention includes a step (a) of irradiating an object to be treated, including an n-type SiC semiconductor, with heating light having a peak wavelength in the range of 420 nm to 490 nm emitted from a light source through a window member to heat the object to be treated. Hereinafter, this optical heating method will be described with reference to the drawings of an optical heating device which is one embodiment of the method.

[0036] In addition, the following drawings are all schematic illustrations, and the dimensional ratios and numbers in the drawings do not necessarily correspond to the actual dimensional ratios and numbers. In the following description, the object to be processed is assumed to be an object to be processed that includes an n-type 4H-SiC semiconductor doped with nitrogen (N) as a dopant. However, as described above, the object to be processed that is the subject of the present invention is assumed to be not only an object to be processed that includes an n-type 4H-SiC semiconductor doped with nitrogen (N), but also an object to be processed that includes a material that can be generally recognized as "n-type SiC" or classified as n-type SiC in the semiconductor industry. This idea is inferred based on the fact that, although it is assumed that the light absorption rate changes somewhat depending on the type of dopant and the crystal structure, it is unlikely that extreme differences in spectrum will appear in materials that are treated as similar products classified in the same category based on SiC.

[0037] Fig. 3 is a cross-sectional view showing a schematic configuration of one embodiment of the optical heating device 1. The optical heating device 1 shown in Fig. 3 includes a chamber 10 in which a workpiece W1 including an n-type SiC semiconductor is accommodated, a light source unit 2, and a radiation thermometer 14. The light source unit 2 includes a plurality of LED elements 11, which are a type of semiconductor light-emitting element, and a support substrate 12 on which the LED elements 11 are placed. More specifically, the light source unit 2 in this embodiment includes a plurality of substrates 20 on which a plurality of LED elements 11 are mounted, and these substrates 20 are placed on the support substrate 12.

[0038] In the following description, as shown in Fig. 3, an XYZ coordinate system will be referred to where appropriate, in which a plane parallel to the main surfaces (W1a, W1b) of the workpiece W1 is defined as the XY plane, and the normal direction of this XY plane is defined as the Z direction. As shown in Fig. 3, the light source unit 2 and the workpiece W1 face each other in the Z direction. When described using this notation, Fig. 5, which will be described later, corresponds to a schematic cross-sectional view of the light heating device 1 cut along the XZ plane.

[0039] In the following, when expressing a direction and distinguishing between positive and negative directions, the direction will be written with a positive or negative sign, such as "+Z direction" and "-Z direction." When expressing a direction without distinguishing between positive and negative directions, the direction will simply be written as "Z direction."

[0040] The light source unit 2 emits heating light L1 having a peak wavelength in the range of 415 nm to 500 nm. In this specification, the peak wavelength of the heating light L1 emitted by the light source unit 2 refers to the wavelength exhibiting the highest light intensity (light output) on the emission spectrum.

[0041] Furthermore, it is more preferable that the light source unit 2 has a main emission wavelength within a range of 415 nm to 500 nm. Specifically, it is preferable to adopt a light source unit 2 in which a wavelength band showing a light intensity of 50% or more of the peak intensity of the heating light L1 falls within a range of 415 nm to 500 nm. Furthermore, it is more preferable to adopt a light source in which a wavelength band showing a light intensity of 50% or more of the peak intensity of the heating light L1 falls within a range of 420 nm to 490 nm. This makes the light source unit 2 a light source more suitable for heat treatment of a workpiece including an n-type SiC semiconductor.

[0042] Furthermore, it is more preferable that the light source unit 2 has a majority of the emission wavelength of the radiated heating light L1 within the range of 415 nm to 500 nm. Specifically, it is preferable to adopt a light source unit 2 in which the wavelength band showing 90% or more of the peak intensity of the heating light L1 falls within the range of 415 nm to 500 nm. Furthermore, it is more preferable to adopt a light source in which the wavelength band showing 90% or more of the light intensity of the peak intensity of the heating light L1 falls within the range of 420 nm to 490 nm. This makes the light source unit 2 a light source more suitable for heat treatment of a workpiece including an n-type SiC semiconductor.

[0043] Fig. 4 shows an example of the spectrum of the heating light L1 having a peak wavelength of 460 nm emitted from the light source unit 2. In Fig. 4, the vertical axis is expressed in logarithm.

[0044] According to the spectrum shown in Fig. 4, in the vicinity of 610nm to 690nm, which is longer than the peak wavelength, the light intensity is about 0.1% to 0.3% of the light intensity at the peak wavelength (area A1 in Fig. 4). This is light originating from impurity levels or defect levels that is inevitably generated when the light source is an LED, and corresponds to the above-mentioned "deep light."

[0045] The light source section 2 included in the light heating device 1 has a shorter emission wavelength range than the LED lamp included in the device of the above-mentioned Patent Document 1.

[0046] As shown in FIG. 3, the chamber 10 includes a support member 13 on the inside. The support member 13 supports the object W1 to be processed so that the main surface W1a and the main surface W1b of the object W1 are arranged on the XY plane. In FIG. 3, the main surface W1b of the object W1 to be processed is arranged to face the light source unit 2. That is, circuit elements, wiring, etc. are formed on the main surface W1a or the main surface W1b, and the main surface W1b is a surface to which the heating light L1 emitted from the light source unit 2 is irradiated. However, the present invention does not exclude a case where the object W1 to be processed is a bare substrate on which wiring, etc. is not formed, and the main surface W1a of the object W1 to be processed is arranged to face the light source unit 2.

[0047] The support member 13 may support the workpiece W1 in any manner as long as the main surface W1a of the workpiece W1 is disposed on the XY plane. For example, the support member 13 may have a plurality of pin-shaped protrusions, and the workpiece W1 may be supported at points by the protrusions.

[0048] As shown in FIG. 3, the chamber 10 includes a first window 10a facing a main surface W1a of the object to be processed W1 supported by the support member 13, and a second window 10b facing a main surface W1b.

[0049] The first window 10a is a window that is used by the radiation thermometer 14 to measure the temperature of the main surface W1a of the workpiece W1. The radiation thermometer 14 is a thermometer that measures the surface temperature of an object to be measured by receiving light emitted from the object to be measured. In this embodiment, the sensitivity wavelength range of the radiation thermometer 14 is a predetermined wavelength range that falls within a range of 0.7 μm to 5 μm. In other words, the first window 10a is made of a material that transmits light that falls within the sensitivity wavelength range of the radiation thermometer 14. As an example, the first window 10a is made of general quartz glass, calcium fluoride, or the like.

[0050] The sensitivity wavelength range of the radiation thermometer 14 included in the light heating device 1 is located on the longer wavelength side than the main emission wavelength range of the heating light L1 emitted from the light source unit 2. More preferably, the lower limit of the sensitivity wavelength range of the radiation thermometer 14 is on the longer wavelength side than the wavelength showing the maximum intensity of the deep light contained in the heating light L1. As described above, the intensity of the deep light is about 0.1% to 0.3% of the peak intensity of the heating light L1, but if the wavelength of this deep light is included in the sensitivity wavelength range of the radiation thermometer 14, there is a possibility that the temperature of the workpiece W1 will be erroneously detected.

[0051] In addition, the shorter the peak wavelength of the heating light L1 emitted from the light source unit 2, the shorter the wavelength of the maximum intensity of the deep light is. Therefore, in order to minimize the overlap between the wavelength range of the deep light and the sensitivity wavelength range of the radiation thermometer 14, the light emission wavelength of the light source unit 2 can be set to a short wavelength or the lower limit of the sensitivity wavelength range of the radiation thermometer 14 can be set to a long wavelength. However, if the sensitivity wavelength range of the radiation thermometer 14 is shifted to the long wavelength side, the relative detection ability of the detection element included in the radiation thermometer 14 decreases, making it difficult to measure the temperature with high accuracy. Therefore, when heating the workpiece W1 while measuring the temperature with high accuracy within the low temperature range, it is preferable to set the light emission wavelength of the light source unit 2 to a short wavelength.

[0052] The second window 10b is a window member for guiding the heating light L1 emitted from the light source unit 2 to the main surface W1b of the workpiece W1. As described above, the peak wavelength of the heating light L1 is within a range of 420 nm to 490 nm. The second window 10b is made of a material having a transmittance of 50% or more for the heating light L1. As an example, the second window 10b is made of synthetic quartz. However, the material of the second window 10b may be appropriately selected depending on the peak wavelength of the heating light L1.

[0053] 5 is a schematic plan view of the light source unit 2 as viewed from the -Z side. As shown in FIG. 5, the light source unit 2 is configured by arranging a plurality of light source regions 12a, each including a plurality of LED elements 11, on a main surface of a support substrate 12. More specifically, the light source regions 12a are formed on a substrate 20. The substrates 20 are placed on the main surface of the support substrate 12.

[0054] In the light source section 2 shown in Fig. 5, a plurality of substrates 20 forming the light source region 12a are regularly arranged. In the present invention, the arrangement pattern of the substrates 20 is not limited, but it is preferable that the substrates 20 are arranged symmetrically when viewed in the Z direction. Typically, it is preferable that the substrates 20 are arranged with line symmetry, point symmetry, or rotational symmetry when viewed in the Z direction. This allows the heating light L1 to be uniformly irradiated onto the main surface W1b of the workpiece W1.

[0055] FIG. 6 is a plan view showing a schematic configuration of the substrate 20. As shown in FIG. 6, the substrate 20 includes a plurality of LED elements 11, an anode electrode 30a, and a cathode electrode 30b. The plurality of LED elements 11 are electrically connected to the anode electrode 30a and the cathode electrode 30b. In the example shown in FIG. 6, a Zener diode 30c is mounted on the substrate 20. The Zener diode 30c is connected in parallel to the plurality of LED elements 11 between the anode electrode 30a and the cathode electrode 30b. The Zener diode 30c is arranged to prevent the LED elements 11 from being deteriorated by static electricity or a surge current.

[0056] 6, the multiple LED elements 11 mounted on the substrate 20 are connected in series and parallel. That is, some of the multiple LED elements 11 are connected in series with each other to form LED element groups 11s, and these LED element groups 11s are connected in parallel with each other.

[0057] Each of the LED elements 11 emits heating light L1 with a peak wavelength in the range of 415 nm to 500 nm. It is preferable that the peak wavelengths of the heating light L1 emitted from the LED elements 11 are substantially the same. The term "substantially the same" here means that a deviation in wavelength caused by element variations during the manufacturing process is acceptable. Typically, the deviation in wavelength may be within ±5 nm.

[0058] According to the optical heating device 1, since the peak wavelength of the heating light L1 emitted from the light source unit 2 is within a range of 415 nm to 500 nm, the heating light L1 is absorbed in the workpiece W1 even if the workpiece W1 includes an n-type SiC semiconductor. This allows non-contact heating of the workpiece W1.

[0059] Furthermore, during the light irradiation process, the radiation thermometer 14 receives the light emitted from the workpiece W1, thereby detecting the temperature of the workpiece W1. As described above, by setting the sensitivity wavelength range of the radiation thermometer 14 to the longer wavelength side than the wavelength showing the maximum intensity of the deep light contained in the heating light L1, it is possible to prevent erroneous detection of the temperature of the workpiece W1 caused by receiving light derived from the deep light. That is, by feeding back the detection result by the radiation thermometer 14 to a controller (not shown) that controls the light output of the light source unit 2, it is possible to heat the workpiece W1 containing an n-type SiC semiconductor with high accuracy. Note that the main emission wavelength range including the peak wavelength of the heating light L1 is clearly outside the sensitivity wavelength range of the radiation thermometer 14.

[0060] It is more preferable that the peak wavelength of the heating light L1 is within a range of 420 nm to 490 nm. In this case, even if the light source unit 2 is installed in the atmosphere, the effect of suppressing the amount of ozone generation can be obtained.

[0061] [Another embodiment] Another embodiment will be described below.

[0062] <1> Fig. 5 illustrates a case where the light source region 12a is square, but this shape is merely an example. Similarly, Fig. 6 illustrates a case where the substrate 20 is rectangular, but this shape is merely an example.

[0063] 5, the plurality of substrates 20 are arranged in a staggered pattern on the support substrate 12, but the arrangement pattern of the plurality of substrates 20 is arbitrary. As another example, the plurality of substrates 20 may be arranged in a ring shape around the center 12c of the support substrate 12.

[0064] In FIG. 6, the multiple LED element groups 11s mounted on the substrate 20 are all composed of the same number of LED elements 11, but the number of LED elements 11 included in the LED element groups 11s may be varied taking into consideration differences in voltage drops that occur depending on the respective distances from the anode electrode 30a and the cathode electrode 30b.

[0065] 3, the first window 10a for measuring the temperature with the radiation thermometer 14 is provided at a position facing the main surface W1a on the opposite side to the main surface W1b of the workpiece W1 to which the heating light L1 is irradiated. However, in the present invention, the position of the first window 10a is arbitrary. For example, the first window 10a may be provided in a side wall of the chamber 10, or may be provided on the main surface W1b side.

[0066] In the latter case, as described above, the sensitivity wavelength range of the radiation thermometer 14 is adjusted so as to be significantly different from the main emission wavelength range of the heating light L1 and not to overlap with the wavelength range in which the deep light has the maximum intensity. As a result, even if the heating light L1 is reflected by the main surface W1b of the workpiece W1, the wavelength range of the reflected light is different from the sensitivity wavelength range of the radiation thermometer 14, so that even if the radiation thermometer 14 receives the reflected light, there is little risk of erroneously recognizing the temperature of the workpiece W1.

[0067] <3> In each of the above-described embodiments, all of the semiconductor light-emitting elements mounted in the light source unit 2 are described as LED elements 11. However, the light source unit 2 may be an LD element, which is a type of semiconductor light-emitting element, or may have a combination of an LED element and an LD element. [Explanation of symbols]

[0068] 1:Light heating device 2:Light source section 10: Chamber 10a: First window 10b: Second window 11: LED element 11s: LED element group 12: Support substrate 12a: Light source area 12c: Center of the support substrate 13: Support member 14: Radiation thermometer 20: Substrate 30a: Anode electrode 30b: cathode electrode 30c : Zener diode L1:Heating light W1: Object to be treated W1a, W1b: Main surfaces of the object to be treated

Claims

1. A light heating method comprising: a step (a) of irradiating a workpiece including an n-type SiC semiconductor with heating light having a peak wavelength in the range of 415 nm to 500 nm emitted from a light source unit having a semiconductor light emitting element through a window member to heat the workpiece.

2. 2. The light heating method according to claim 1, wherein the heating light has a peak wavelength in the range of 420 nm to 490 nm.

3. 3. The optical heating method according to claim 1, further comprising a step (b) of measuring the temperature of the object to be treated by a radiation thermometer having a sensitivity wavelength range of a predetermined wavelength range ranging from 0.7 μm to 5 μm during the execution of the step (a) by receiving light radiated from the object to be treated.

4. An optical heating device for an n-type SiC semiconductor, A chamber that accommodates a workpiece including an n-type SiC semiconductor; a support member for supporting the workpiece in the chamber; A light source unit that emits heating light having a peak wavelength in the range of 415 nm to 500 nm; a window member that passes the heating light emitted from the light source unit and guides it to the object to be treated.

5. The light source unit includes a plurality of substrates on which a plurality of semiconductor light emitting elements are mounted, The optical heating device for n-type SiC semiconductor according to claim 4, wherein the plurality of substrates are arranged in line symmetry, point symmetry, or rotational symmetry when viewed in a normal direction to the main surfaces of the substrates.

Images