JP2000138092A - Optical irradiation heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical irradiation heating device capable of homogeneously heating a treatment item, and easily controlling the distribution curve of energy emitted from a heating light source lamp to a desired shape. SOLUTION: A plurality of heating units made of a heating light source lamp 1 and a glass prism block 3 are arranged. Light emitted from the lamp 1 is incident on the prism block 3 from one edge thereof, and outgoes from the other edge of the prism block 3, repeating total reflection at the side of the prism block 3, thereby heating a treatment item. A quarts glass containing <=5 ppm of an OH group is used as the prism block 3. Also, a halogen incandescent lamp having peak wavelength <=3 μm is used as the lamp 1. Furthermore, the irradiation energy per unit area for light emitted from the heating unit is made different among the heating units.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light irradiation type heating device for heating an object to be processed (work) with light emitted from a heating light source lamp.

[0002]

2. Description of the Related Art A light irradiation type heating apparatus using a heating light source lamp as a heat source reflects light from a rod-shaped or spherical halogen incandescent lamp, which is a heating light source lamp arranged in a plane, with a reflecting mirror. The workpiece is heated by irradiating the reflected light, but the temperature can be raised to 1000 ° C or more in a few seconds. If the light irradiation is stopped, the workpiece can be cooled rapidly. It is widely used as a heating device for cooling heat treatment. Also, of the light emitted from the heating light source lamp, ultraviolet light and visible light are more absorbed by the work than infrared light and converted into heat when the work is a silicon wafer. A lamp that emits light including the light may be used as a light source lamp for heating.

[0003]

FIG. 1 shows an example of a conventional light irradiation type heating device, in which a halogen incandescent lamp as a heating light source lamp 1 is arranged in a plane and reflected on the back of the halogen incandescent lamp. A mirror 2 is arranged, and the light emitted from the halogen incandescent lamp is directly and reflected by the reflecting mirror to heat a flat work (not shown). At this time,
If a halogen incandescent lamp is theoretically a point light source and the reflected light from the reflector is perfectly parallel light, the radiant energy per unit area of light on the work will be uniform, but in practice,
A halogen incandescent lamp is not a theoretical point light source but has a certain size, and the light reflected by the reflector is not perfectly parallel light. Therefore, the area immediately below the halogen incandescent lamp is large and decreases as the distance from the area decreases. It is conceivable to select the shape of the reflecting mirror so that the workpiece can be heated uniformly. However, such a reflecting mirror is not practical because it has a complicated structure, requires much time for designing and manufacturing, and increases the cost.

[0004] Therefore, when a halogen incandescent lamp covered with a reflecting mirror is arranged in a plane to heat a work having a wide surface, the temperature distribution curve of the work is, as shown in FIG. It has a shape similar to a sine curve with a series of molds, and cannot be heated uniformly.

[0005] In addition, since heat is radiated from the outer peripheral edge of a planar work, even if the heating source performs uniform heating, the temperature of the peripheral portion is lower than that of the central portion of the work, and the work is uniformly heated. Can not do it. For this reason, conventionally, the radiation energy of the peripheral lamp is made larger than that of the central lamp to compensate for the radiation of heat from the outer peripheral edge of the work. Since the lights of the lamps greatly influence each other, it has been difficult to control the distribution curve of the radiant energy of the entire heat source including a plurality of lamps to a desired shape.

Accordingly, a first object of the present invention is to provide a light irradiation type heating device capable of uniformly heating a work, and a second object is to individually emit light from a plurality of heating units. An object of the present invention is to provide a light irradiation type heating device capable of easily controlling a distribution curve of energy emitted from the entire heating unit to a desired shape by individually controlling energy by a heating light source lamp.

[0007]

In order to achieve the first object, a first aspect of the present invention is to dispose a plurality of heating units each including a heating light source lamp and a prismatic block made of glass. Light emitted from the heating light source lamp enters the block from one end face of the block, and is emitted from the other end face of the block while repeating total reflection on the side face of the block to heat the work.

In the case where the prismatic block is made of quartz glass, if the amount of OH groups contained in the quartz glass is large, light (infrared rays) of a specific wavelength is well absorbed by the quartz glass, and light of a specific wavelength radiated from the heating light source lamp. Since light (infrared rays) cannot be used efficiently, the OH group content of the quartz glass is set to 5 ppm or less and light (infrared rays) of a specific wavelength emitted from the heating light source lamp is quartz. It is desirable not to be absorbed by the glass. Also,
When a halogen incandescent lamp having a peak wavelength of radiated light of 3 μm or less is used as the heating light source lamp, the amount of light absorbed by the prismatic block made of quartz glass is small and the halogen incandescent lamp emits light. The light can be used efficiently.

According to a fourth aspect of the present invention, in order to achieve the second object, in the first to third aspects of the present invention, the radiant energy per unit area of light emitted from the heating unit is made different depending on the heating unit.

[0010]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 2 shows a perspective view of an embodiment of the present invention. In FIG. 2, a heating light source lamp 1 as a heat source is a one-end sealed halogen incandescent lamp having a rated power consumption of 1 kW that emits light containing a large amount of infrared rays. The peak wavelength of the halogen incandescent lamp is, for example, 1 μm. It is. As the light source lamp 1 for heating, in addition to the halogen incandescent lamp, a xenon lamp or a mercury lamp that emits light containing a large amount of ultraviolet light or visible light can be used.
The heating light source lamp 1 is covered with a concave reflecting mirror 2 having a bowl shape. A glass prism block 3 (square prism block in the illustrated example) is disposed below the heating light source lamp 1, and the heating light source lamp 1, the reflecting mirror 2, and the prism block 3 constitute a heating unit. . Then, a plurality of heating units are arranged, and a flat work W is arranged below the heating units. The reflecting mirror 2
Are attached as needed.

FIG. 3 shows the state of reflection of light in the prism block 3. In FIG. 3, a prism block 3 is formed of a glass having a large refractive index of light, such as quartz glass or Pyrex glass, into a prism shape. The light emitted from the heating light source lamp 1 is incident directly and on the upper end surface of the prism block 3 after being reflected by the reflecting mirror 2. Here, according to Snell's law, the refractive index of light of the prism block 3 is 1.
If the angle is 41 (以上 2) or more, light incident on the prism block 3 at an extremely large incident angle θ1 close to 90 ° is also shifted from the axis of the prism block 3 by θ2 as shown by a solid arrow in FIG.
Becomes light having an angle component within 45 °. That is, all the light incident on the upper surface of the prism block 3 is
It becomes light having an angle component within 45 ° from the axis of the light. And
The refractive index of quartz glass for light having a wavelength of 1.0 μm is 1.
45, and the refractive index of Pyrex glass with respect to light having a wavelength of 1.0 μm is 1.47. Therefore, in the prism block 3 made of quartz glass or Pyrex glass,
All of the light incident on the upper surface of the prism block 3 becomes light having an angle component whose θ3 is within 45 ° from the axis of the prism block 3 as shown by a broken arrow in FIG.

Accordingly, of the light incident on the upper surface of the prism block 3, the light incident on the side surface of the prism block 3 has θ4 of 4
Since it is incident at an angle of 5 ° or more, prism block 3
Is totally reflected on the side surface of the prism block 3 and does not directly go out of the side surface of the prism block 3. Then, the light totally reflected on the side surface of the prism block 3 is totally reflected again on the opposite side surface, and transmits through the prism block 3 while repeating total reflection. Prismatic block 3
As the length of the light in the transmission direction becomes longer, the amount of light transmitted directly without being reflected on the side surface of the prism block 3 decreases, and the ratio of light transmitted while repeating total reflection increases, and the number of times of total reflection also increases. More. Then, the light that has been subjected to total reflection on the side surface of the prism block 3 is emitted from the lower end surface of the prism block 3 together with the light that directly passes through the prism block 3 to heat the work W. Thus, the prism block 3
By repeating the total reflection of light many times on the side surface, the difference in radiant energy depending on the location on the irradiated surface below the prismatic block 3 is reduced, and the work W can be uniformly heated. The reason why the uniform heating can be performed will be described in detail below.

FIG. 4 shows an image of the lamp 1 when the lamp 1 is viewed from the lower end face of the prism block 3 which is the surface to be irradiated.
The light that does not directly pass through the prism block 3 and is totally reflected on the side surface of the prism block 3 appears to be coming from a plurality of lamp virtual images indicated by dotted lines, so that a very large number of light sources are present. The number of light sources increases as the number of times that light is totally reflected on the side surface of the prism block 3 increases. Therefore, on the surface to be illuminated, light is emitted from an extremely large number of light sources, and there is no difference in radiant energy depending on the location of the surface to be illuminated, so that the workpiece can be heated uniformly. Therefore, as shown in FIG. 5, the temperature distribution curve of the work becomes an extremely flat curve. Further, since light does not escape from the side surface of the prism block 3 and all the light incident on the prism block 3 can be used for heating, extremely highly efficient heating is possible.

As described above, although the temperature distribution curve of the work is an extremely flat curve, since the heat is radiated also from the outer peripheral edge of the work, the temperature of the end of the work is inevitably low. Therefore, it is preferable to increase the radiant energy of the light radiated from the lamp 1 of the heating unit at the end. As a specific means, there is a means for increasing the electric power of the lamp of the heating unit at the end compared to the lamps of the other heating units. In the conventional light irradiation type heating apparatus shown in FIG. 1, even if the radiant energy of the light of the lamp at the end is increased, it is difficult to finely control the influence by the light emitted from the adjacent lamp. In the present invention, since the light for heating the work is independent for each heating unit, it is hardly affected by the adjacent lamp. Therefore, by individually controlling the energy individually emitted from the plurality of heating units by the heating light source lamp, the distribution curve of the energy emitted from the entire heating unit can be easily controlled to a desired shape, and the workpiece can be easily controlled. The temperature at the end can be made equal to that at the center.

As described above, a halogen incandescent lamp, a xenon lamp, a mercury lamp, or the like is used as the light source lamp 1 for heating.
Emit light with a wavelength of 3 μm. Some of the light emitted from this lamp may be absorbed by the prism block 3. When the prism block 3 is made of quartz glass, it contains many OH groups depending on the manufacturing method, and the OH groups contained in the quartz glass affect the light transmittance. FIG. 6A shows OH
Glass with a base content of 130 ppm (thickness 30 m
FIG. 6B is a spectral transmission characteristic diagram of quartz glass having an OH group content of 5 ppm. As can be seen, the content of OH groups is 130 p.
The pm quartz glass well absorbs light having a wavelength of 1.4 μm and 2.2 μm (infrared light) out of the light emitted from the heating light source lamp 1, and especially 2.7 μm light almost at a peak. Absorb completely. Therefore, 1.4 μm,
Light of 2.2 μm (infrared ray) is not efficiently used.
The light of 7 μm does not reach the irradiated surface. On the other hand, when the content of the OH group is as low as 5 ppm, the light of these wavelengths is not absorbed at the peak, and is transmitted well. The transmittance of light having a wavelength of 3 μm is about 63.
%, And light having a longer wavelength is hardly transmitted. Therefore, when the prism block 3 is formed of quartz glass, the light emitted from the heating light source lamp 1 can be used efficiently if the OH group content is 5 ppm or less. Specifically, anhydrous quartz glass formed by vacuum melting is preferable because it hardly contains OH groups. The halogen incandescent lamp emits light containing a large amount of infrared rays, and its peak wavelength can be set arbitrarily within a relatively wide range. However, when the peak wavelength is 3 μm or more, as shown in FIG. Light that is largely absorbed by and transmitted by the quartz glass that is the prism block 3 is reduced, and heating cannot be performed efficiently. Therefore, when a halogen incandescent lamp is used as the light source lamp 1 for heating, it is preferable that the peak wavelength is 3 μm or less.

As shown in FIG. 2, when the heating units are arranged side by side, when the adjacent prism blocks 3 are brought into close contact with each other, the light incident on the side surfaces of the prism blocks 3 is not totally reflected by the side surfaces, and the adjacent prism blocks are not totally reflected. 3 may be incident. Therefore, it is necessary to leave a space between adjacent prism blocks 3. However, if this interval is wide, the radiation energy at the boundary of the prism block 3 decreases,
Since it becomes impossible to heat uniformly, the adjacent prism block 3
It is preferable that they are separated from each other by, for example, about 0.1 mm.

When a spherical heating light source lamp sealed at one end is used, in order to arrange the heating units side by side, the cross-sectional shape of the prismatic prism block 3 is not limited to the square shape shown in FIG. , Hexagons or triangles can also be used. As described above, the prism block 3 having a triangular, quadrangular or hexagonal cross section can be used in a dense structure, while the prism block 3 having a cross section of any other shape has a dense structure. Because it can not be arranged
When a plurality of heating units are arranged side by side, there is a large space between adjacent prism blocks 3 and heating cannot be performed uniformly.

When a rod-shaped heating light source lamp sealed at both ends is used, as shown in FIG.
The heating unit is composed of a gutter-shaped reflecting mirror 2 covering the rectangular prism and a rectangular column block 3 having a rectangular cross section. Then, the heating units are arranged side by side in a row to form a heat source, and a planar work W is arranged below the prism block 3. In this case, too, light is coming from an extremely large number of light sources. , And the planar workpiece can be heated uniformly. In addition,
Also at this time, if the prism blocks 3 are brought into close contact with each other, light incident on the side surfaces of the prism blocks 3 may enter the adjacent prism blocks 3 without being totally reflected on the side surfaces. 0.1mm between 3
Open.

[0019]

As described above, in the light irradiation type heating apparatus of the present invention, a plurality of heating units each comprising a heating light source lamp and a prismatic block made of glass are arranged side by side, and the heating light source lamp emits light. Light is incident on the prism block from one end surface of the prism block, and is emitted from the other end surface of the prism block while repeating total reflection on the side surface of the prism block to heat the workpiece. This is equivalent to heating the object with the emitted light, and the object can be heated very uniformly.
When the prism block is made of quartz glass, the OH group content of the quartz glass is set to 5 ppm or less, and a halogen incandescent lamp having a peak wavelength of emitted light of 3 μm or less is used as a heating light source lamp. In addition, the amount of infrared rays absorbed by the quartz glass is reduced, and heating can be performed efficiently. Further, by making the radiation energy per unit area of the light emitted from the heating unit different depending on the heating unit, the distribution curve of the energy emitted from the entire heating unit can be easily controlled to a desired shape.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a conventional example.

FIG. 2 is a perspective view of an embodiment of the present invention.

FIG. 3 is an explanatory diagram of a light reflection state in a prism block.

FIG. 4 is an explanatory diagram of reflection of light in a prism block and a virtual image of a lamp.

FIG. 5 is an explanatory diagram of a light reflection state and a temperature distribution in a prism block.

FIG. 6 is a spectral transmittance characteristic diagram of quartz glass containing an OH group.

FIG. 7 is a perspective view of another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating light source lamp 2 Reflector 3 Square prism block

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kishi Owada 1194, Sado, Bessho-cho, Himeji, Hyogo Ushio Electric Co., Ltd. (72) Inventor Hitoshi Nakabayashi 1194, Sado, Bessho-cho, Himeji, Hyogo Ushio Electric Inside (72) Inventor Akinobu Nakajima 1194 Sado, Bessho-cho, Himeji-shi, Hyogo USHIO Electric Co., Ltd.F-term (reference) 3K058 AA00 CE17 CE31 EA01 3K092 PP20 QA07 QB80 RD10 RD11 SS40 SS47 VV21

Claims (4)

[Claims] 1. A heating unit comprising a heating light source lamp and a prismatic block made of glass is arranged in a plurality, and light emitted by the heating light source lamp enters the block from one end surface of the block. A light irradiation type heating device, which emits light from the other end surface of the block and heats the object to be processed, while repeating total reflection on the side surface of the heating device. 2. The light irradiation type heating device according to claim 1, wherein the prism block is made of quartz glass having an OH group content of 5 ppm or less. 3. The light irradiation type heating apparatus according to claim 2, wherein the heating light source lamp is a halogen incandescent lamp having a peak wavelength of emitted light of 3 μm or less. 4. The heating unit according to claim 1, wherein radiant energy per unit area of light emitted from the heating unit is varied depending on the heating unit.
The light irradiation type heating device according to any one of the above.