JP7477491B2 - Heat reflector - Google Patents

Description

The present disclosure relates to a heat reflector that can be used, for example, in the field of semiconductors and electronic components, as a heat reflector in various heat treatment devices that heat treat wafers, substrates, etc. at low to high temperatures, and that has a short time required for one heating/cooling cycle and a high reflectivity, thereby enabling energy saving in the heat treatment device and suppressing contamination.

In the manufacturing or processing of semiconductor wafers, heat treatment is carried out to impart various properties to the semiconductor wafers. For example, the semiconductor wafers are stored in a furnace core tube made of high-purity quartz, and the heat treatment is carried out by controlling the atmosphere inside the furnace core tube. In the heat treatment equipment used in this heat treatment process, a heat retaining body (lid) is provided between the furnace interior and the hearth to cover the furnace opening in order to maintain a high temperature inside the furnace and prevent heat dissipation to the hearth.

One such heat retaining body is one that blocks the opening of the heat treatment chamber, has quartz plates that are stacked at a distance from each other and are exposed to the heat treatment chamber, and has the following characteristics: the quartz plates have smooth, bubble-free surfaces, and a thin gold film is formed inside the quartz plates, the thin gold film being formed by gold vapor deposition (see, for example, Patent Document 1).

In addition, a technology has been disclosed in which a mixture of platinum (Pt) and oxides (such as SiO or PbO) is mixed with organic matter to form a paste on a quartz plate having a hole for passing a quartz tube through the center and a hole for passing a quartz rod through, and then the paste is applied by screen printing and baked to form a reflective surface made of a resistive heating element, for example, 5 to 10 microns thick (see Patent Document 2, for example).

There is a disclosure of a technology in which the thermal insulation structure of a vertical heat treatment furnace is composed of multiple support columns and multiple reflective heat shield plates provided at predetermined intervals on the support columns in the vertical direction (see, for example, Patent Document 3). According to Patent Document 3, the heat shield plate is formed of a reflective film and a transparent quartz layer that covers the surface of the reflective film. One method of forming this heat shield plate is to use a pair of circular transparent quartz plates that form the transparent quartz layer, provide a reflective film on one surface of one of the transparent quartz plates, sandwich this reflective film between the other transparent quartz plate, and weld the peripheries of both transparent quartz plates to seal and integrate them.

JP 2001-102319 A Japanese Patent Application Laid-Open No. 9-148315 Japanese Patent Application Laid-Open No. 11-97360 JP 2019-217530 A Patent No. 4172806 Patent No. 6032667

In Patent Document 1, the presence of a heat retaining body to prevent metal contamination slows down the heating and cooling response of the furnace body, resulting in a longer heat treatment cycle. In addition, the quartz plates need to be welded on the outer periphery to prevent metal contamination, and in order to maintain a high reflectance, it is necessary to minimize the joint width between the quartz plates in order to maximize the metal film area relative to the quartz plate area. In Patent Document 1, which does not do this, there are problems with the delayed heating and cooling response in the heat treatment process, which has a temperature rise profile up to the heat treatment temperature, a temperature maintenance profile, and a temperature drop profile, causing deviations from the desired profiles, and also lengthening the time required for one heat treatment cycle, resulting in a decrease in production efficiency.

In Patent Document 2, a heater conduction point is provided in the center using a quartz tube in order to use it as a reflector and heater, but this structure creates some areas where the radiant heat cannot be completely blocked. In order to achieve even greater energy savings, it is necessary to increase the reflective surface area rate and make the quartz that forms the reflector and exterior thinner to reduce the thermal capacity.

In Patent Document 3, the metal is sandwiched between quartz plates and welded, but because of the effect of heat, there is a problem that the film peels off when it is applied to a thin film, and it is also difficult to reduce the weld width. Furthermore, it is difficult to weld while maintaining a vacuum inside, and there is an unavoidable risk that the thin film will be damaged due to an increase in internal pressure when used at high temperatures. Even with the method of pouring transparent quartz, when applied to a thin metal film, thermal and physical damage cannot be avoided, and it is also difficult to make the transparent quartz thin. Also, in Patent Document 3, the heat shield plate delays the response of heating and cooling in the heat treatment process, causing deviations from the desired profiles, and also lengthens the time required for one heat treatment cycle, resulting in a decrease in production efficiency.

The objective of this disclosure is to provide a heat reflector that can secure a higher reflective area ratio than conventional methods, has a small heat capacity that allows for energy savings, has a high reflectivity, suppresses contamination inside the furnace, and has good thermal response.

As a result of intensive research, the inventors have found that the above problem can be solved by setting the heat capacity of the plate-shaped exterior and the reflector in the thickness direction per 1 ^mm2 of the heat reflector within a predetermined range, and have completed the present invention. That is, the heat reflector of the present invention is a heat reflector having a plate-shaped exterior and a reflector that is disposed inside the plate-shaped exterior and completely covers the outer periphery with the plate-shaped exterior, and reflects infrared rays incident on one surface of the plate-shaped exterior, the reflector being a thin film, plate or foil, and the heat reflector is characterized in that the total heat capacity of the plate-shaped exterior and the reflector in the thickness direction per ¹ mm2 is 0.0004 to 0.0080 (J/K).

In the heat reflector according to the present invention, the surface layer including at least the reflective surface of the reflector is preferably made of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, or an alloy containing at least one selected from the group consisting of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu.

In the heat reflector of the present invention, the material of the plate-shaped exterior is preferably silica or silicon.

In the heat reflecting plate according to the present invention, the plate-shaped exterior preferably has a laminated plate structure in which a first exterior plate and a second exterior plate are arranged opposite each other and their peripheral edges are continuously joined in a ring shape along the periphery. Because the plate-shaped exterior and the reflector can be made thin, the heat capacity can be reduced.

In the heat reflecting plate according to the present invention, it is preferable that the laminated plate has a structure in which a cavity is provided between the opposing surfaces of the first exterior plate and the second exterior plate, and is sealed by the joint between the peripheral portions on at least one of the first exterior plate side and the second exterior plate side, and the reflector is disposed in the cavity. Since the reflector is located in the cavity, which is an enclosed space, the joint between the peripheral portions is less susceptible to stress in the peeling direction caused by the reflector, and contamination inside the furnace due to damage to the reflector can be suppressed. Furthermore, damage due to the difference in thermal expansion between the plate-shaped exterior and the reflector can be avoided.

The heat reflector according to the present invention has the cavity at least on the first exterior plate side, and has a thin film formed as the reflector on the surface inside the cavity of the first exterior plate, and the thin film is a laminated film having, in order from the surface side inside the cavity of the first exterior plate, a base film and a reflective film as a surface layer including the reflective surface, and the base film is made of Ta, Mo, Ti, Zr, Nb, Cr, W, Co or Ni, or Ta, Mo, Ti, Zr, Nb, Cr, W, Co and Ni The reflective film is made of an alloy containing at least one selected from the group consisting of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, or is made of an alloy containing at least one selected from the group consisting of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, and it is preferable that the base film and the reflective film have different compositions. Since a reflector is formed on the surface inside the cavity of the first exterior plate, the joint between the peripheral parts is less likely to be subjected to stress in the peeling direction caused by the reflector, and contamination inside the furnace due to damage to the reflector can be suppressed. Furthermore, damage due to the difference in thermal expansion between the plate-shaped exterior and the reflector can be avoided.

In the heat reflector according to the present invention, the first exterior plate is a flat plate, has the cavity on the second exterior plate side, and has a thin film formed on the surface of the first exterior plate as the reflector, and the thin film is a laminated film having, in order from the surface side of the first exterior plate, a base film and a reflective film as a surface layer including the reflective surface, and the base film is made of Ta, Mo, Ti, Zr, Nb, Cr, W, Co or Ni, or is selected from the group consisting of Ta, Mo, Ti, Zr, Nb, Cr, W, Co and Ni. The reflective film is made of an alloy containing at least one selected from the group consisting of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, or is made of an alloy containing at least one selected from the group consisting of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, and it is preferable that the base film and the reflective film have different compositions. Since a thin film as a reflector is formed on the first exterior plate, which is a flat plate, it can be a heat reflector with excellent productivity.

In the heat reflector of the present invention, the reflector is preferably a plate or foil, and is made of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, or an alloy containing at least one selected from the group consisting of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu. The plate or foil as the reflector is contained within the cavity, and corrosion of the plate or foil is unlikely to occur. Furthermore, the joint between the peripheral portions is unlikely to be subjected to stress in the peeling direction caused by the plate or foil.

In the heat reflector according to the present invention, it is preferable that the pressure inside the cavity is reduced to less than atmospheric pressure. This can prevent the internal pressure of the cavity from increasing during heat treatment, and can further prevent contamination inside the furnace.

In the heat reflecting plate according to the present invention, (1) the first exterior plate has a bank portion provided on the peripheral portion and a recess surrounded by the bank portion to form the cavity, and the second exterior plate is flat, or (2) the first exterior plate is flat, and the second exterior plate has a bank portion provided on the peripheral portion and a recess surrounded by the bank portion to form the cavity. By providing a recess in the first exterior plate, a cavity can be provided in the plate-shaped exterior with a simple structure. Alternatively, by providing a recess in the second exterior plate, a cavity can be provided in the plate-shaped exterior with a simple structure.

In the heat reflecting plate according to the present invention, it is preferable that the heat reflecting plate has at least one support section that stands between the opposing faces of the laminated plate structure within the cavity. The support section can increase the bonding strength of the laminated plate structure.

The heat reflecting plate according to the present invention includes a configuration in which the support portion is columnar or tubular. By making it columnar or tubular, it is possible to increase the bonding strength while increasing the area of the reflector.

In the heat reflecting plate according to the present invention, it is preferable that the heat reflecting plate has a plurality of support parts, the support parts are cylindrical, and each support part has a three-dimensional space-filling structure in which each support part shares a part of the cylindrical wall with the other support part. By adopting a three-dimensional space-filling structure, it is possible to increase the surface area of the reflector while increasing the bonding strength, and further increase the strength of the reflecting plate itself.

In the heat reflector of the present invention, the three-dimensional space-filling structure includes a honeycomb structure, a rectangular lattice structure, a square lattice structure, or a diamond lattice structure.

In the heat reflecting plate according to the present invention, the opposing surfaces of the first exterior plate and the second exterior plate are flat surfaces, and the reflector is a thin film formed on the surface of the first exterior plate on the second exterior plate side in an area inside the annular joint between the peripheral portions, and the thin film is a laminated film having, in order from the surface side of the first exterior plate, a base film and a reflective film as a surface layer including the reflective surface, and the base film is made of Ta, Mo, Ti, Zr, Nb, Cr, W, Co, or Ni, or Ta, Mo, Ti, Zr, Nb, C The reflector is made of an alloy containing at least one selected from the group consisting of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, or is made of an alloy containing at least one selected from the group consisting of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, and it is preferable that the base film and the reflector have different compositions. This can further suppress interference fringes caused by partial contact between the reflector and the second exterior plate.

The heat reflector according to the present invention has the cavity at least on the first exterior plate side, and has a thin film formed as the reflector on the surface inside the cavity of the first exterior plate, and the thin film is preferably a film made of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, or an alloy film containing 50 mass% or more of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu. When it is a metal film or an alloy film containing 50 mass% or more of these metals, the thin film formed as the reflector may be a single layer film.

In the heat reflector according to the present invention, the first exterior plate is a flat plate, the cavity is on the second exterior plate side, and a thin film is formed on the surface of the first exterior plate as the reflector, and the thin film is preferably a film made of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, or an alloy film containing 50 mass% or more of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu. When it is a metal film or an alloy film containing 50 mass% or more of these metals, the thin film formed as the reflector may be a single layer film.

In the heat reflector according to the present invention, the opposing surfaces of the first exterior plate and the second exterior plate are flat surfaces, and the reflector is a thin film formed on the surface of the first exterior plate on the second exterior plate side in an inner region of the annular joint between the peripheral portions, and the thin film is preferably a film made of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, or an alloy film containing 50 mass% or more of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu. When it is a metal film or an alloy film containing 50 mass% or more of these metals, the thin film formed as the reflector may be a single layer film.

The heat reflector according to the present invention has the cavity on the first exterior plate side and the second exterior plate side, and has a thin film formed as the reflector on the surface inside the cavity of the first exterior plate, and the thin film is preferably a film made of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, or an alloy film containing 50 mass% or more of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu. When it is a metal film or an alloy film containing 50 mass% or more of these metals, the thin film formed as the reflector may be a single layer film.

In the heat reflecting plate according to the present invention, it is preferable that the thickness of the reflector is 0.01 μm or more and 5 mm or less. This makes it possible to reduce the thermal capacity of the heat reflecting plate while maintaining the efficiency of reflecting radiant heat by the reflector.

In the heat reflector according to the present invention, the joint between the peripheral portions is preferably a surface activated joint. By making the joint width shorter than that of typical welding methods, more radiant heat can be reflected into the furnace. In addition, the thin film that serves as the reflector is less susceptible to thermal and physical damage caused by the joining process. In addition, the joint strength at the joint is increased, which extends the life of the heat reflector, improves corrosion resistance, and suppresses contamination inside the furnace.

The heat reflector according to the present invention includes the following heat reflectors.
A plate-shaped exterior;
a heat reflector including: a reflector disposed inside the plate-shaped exterior, the outer periphery of which is completely covered by the plate-shaped exterior, and which reflects infrared rays incident on one surface of the plate-shaped exterior,
The plate-like exterior has a laminated plate structure having a joint in which a flat surface of a flat first exterior plate and a flat surface of a flat second exterior plate are arranged opposite each other and the peripheral portions are continuously joined in a ring shape along the peripheral portions,
the reflector is a thin film formed on an inner region of the annular joint between the peripheral portions of the flat surface of the first exterior plate,
The outer plate surfaces of the first exterior plate and the second exterior plate are flat surfaces over their entire surfaces,
The entire surface surrounded by the periphery of the thin film is a reflective surface, and
The reflector is a thin film, a plate, or a foil;
The heat reflector is 1 mm ² The total heat capacity of the plate-like exterior and the reflector in the thickness direction is 0.0004 to 0.0080 (J/K).

In the heat reflecting plate according to the present invention, it is preferable that the thin film is a film made of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge , Ag, or Cu, or an alloy film containing 50 mass % or more of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge , Ag , or Cu, and that the thin film is a single layer film.

In the heat reflecting plate according to the present invention, the thin film is a laminated film having, in order from the front surface side of the first exterior plate, a base film and a reflective film as a surface layer including the reflective surface,
The undercoat film is made of Ta, Mo, Ti, Zr, Nb, Cr, W, Co, or Ni, or is made of an alloy containing at least one selected from the group consisting of Ta, Mo, Ti, Zr, Nb, Cr, W, Co, and Ni,
the reflective film is made of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge , Ag, or Cu, or is made of an alloy containing at least one selected from the group consisting of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge , Ag , or Cu;
It is preferable that the undercoat film and the reflective film have different compositions.

In the heat reflecting plate of the present invention, the joint includes a form in which no cavity is provided in the first exterior plate and the second exterior plate, the flat surface of the flat first exterior plate and the flat surface of the flat second exterior plate are arranged opposite each other, and the peripheral portions are joined continuously in a ring shape along the periphery by stress deformation of the first exterior plate and the second exterior plate.

In the heat reflecting plate according to the present invention, it is preferable that the thin film is formed on the entire surface of the flat surface of the first exterior plate in an area inside an annular joint between the peripheral portions.

In the heat reflector according to the present invention, the thin film preferably has a thickness of 10 nm or more and 500 nm or less.
The heat reflector according to the present invention includes a heat reflector to be placed at a position where infrared rays from inside a furnace of a heat treatment device are directly incident thereon.

The present disclosure provides a heat reflector that can secure a higher reflective area ratio than conventional methods, has a small heat capacity that allows for energy savings, has a high reflectivity, suppresses contamination inside the furnace, and has good thermal response.

FIG. 2 is a schematic plan view showing an example of a heat reflector according to the present embodiment. FIG. 2 is a schematic diagram showing a first example of the AA cross section. FIG. 11 is a schematic diagram showing a second example of the AA cross section. FIG. 11 is a schematic diagram showing a third example of the AA cross section. FIG. 11 is a schematic diagram showing a fourth example of the AA cross section. FIG. 11 is a schematic diagram showing a fifth example of the AA cross section. FIG. 13 is a schematic diagram showing a sixth example of the AA cross section. FIG. 13 is a schematic diagram showing a seventh example of the AA cross section. FIG. 13 is a diagram showing an example of a form in which the support portion has a honeycomb structure. FIG. 13 is a schematic diagram showing an eighth example of the AA cross section. FIG. 13 is a schematic diagram showing a ninth example of the AA cross section. FIG. 13 is a schematic diagram showing a tenth example of the AA cross section. FIG. 11 is a schematic diagram showing an eleventh example of the AA cross section. FIG. 12 is a schematic diagram showing a twelfth example of the AA cross section. FIG. 13 is a schematic diagram showing a thirteenth example of the AA cross section. 1 is a graph showing the reflectance of a reflector of Example 1. 1 is a graph showing the relationship between the wavelength and the amount of blackbody radiation emitted by a material at 1000° C. 13 is a graph showing the reflectance of the reflector of Example 5. 13 is a graph showing the reflectance of the reflector of Example 6. FIG. 21 is a schematic diagram showing a 14th example of the AA cross section. 1 is a graph showing the reflectance of opaque quartz of Comparative Example 1.

The present invention will be described in detail below with reference to embodiments, but the present invention should not be interpreted as being limited to these descriptions. Various modifications of the embodiments may be made as long as the effects of the present invention are achieved.

(Reflector is a thin film)
The heat reflector according to the present embodiment will be described with reference to Fig. 1 and Fig. 2. The heat reflector 100 according to the present embodiment includes a plate-shaped exterior 1 and a reflector 5 that is disposed inside the plate-shaped exterior 1, has an outer periphery completely covered by the plate-shaped exterior 1, and reflects infrared rays incident on one surface of the plate-shaped exterior 1. In Fig. 1, the direction toward the paper surface is the direction of incidence of infrared rays. In Fig. 2, the direction from top to bottom is the direction of incidence of infrared rays. The reflector 5 is a thin film, and the surface layer including at least the reflection surface of the reflector 5 is preferably made of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, or an alloy containing at least one selected from the group consisting of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu. 2 shows a form in which the reflector 5 is a laminated film, and a reflective film 4 is formed as a surface layer including a reflective surface on an undercoat film 3. In this case, it is preferable that the reflector 5 is not provided with through holes or irregularities, and the entire surface surrounded by the periphery of the reflector is a reflective surface.

The heat reflector 100 according to this embodiment has a total heat capacity of the plate-shaped exterior and the reflector in the thickness direction per ¹ mm2 of 0.0004 to 0.0080 (J/K), preferably 0.0023 to 0.0070 (J/K), and more preferably 0.0030 to 0.0060 (J/K). The heat capacity of the plate-shaped exterior and the reflector in the thickness direction per ^{1 mm2} corresponds to the value obtained by dividing the heat capacity of the heat reflector 100 having the reflector 5 and the plate-shaped exterior 1 completely covering the outer periphery of the reflector 5 by the area of the infrared incidence surface. The area of the infrared incidence surface refers to the area of the area including both the area where the reflector 5 is visible and the area where the joint 2 between the peripheral parts is visible, that is, the entire area of the plate surface of the plate-shaped exterior 1 when the reflector 5 is viewed from the front. If the total heat capacity of the plate-shaped exterior and the reflector in the thickness direction per ¹ mm2 is less than 0.0004 (J/K), the plate-shaped exterior may be damaged due to insufficient thickness, or the reflector may be too thick to allow infrared light to pass through, resulting in a decrease in reflective performance. If it exceeds 0.0080 (J/K), the total heat capacity will be too large, slowing down the heating and cooling response in the heat treatment process and causing deviations from the desired profiles. Also, the time required for one heat treatment cycle will be prolonged, resulting in a decrease in production efficiency.

In the present embodiment, the heat reflector must satisfy the above range for the total heat capacity in the thickness direction of the plate-shaped exterior and the reflector per ¹ mm2. In addition to satisfying this range, in order to further improve the thermal response of the furnace body, it is more preferable that the ratio of the area of the reflector to the plate-shaped exterior in the in-plane direction is large and the reflectance of the reflective material used for the reflector is high. For example, the heat reflector is designed according to the size of the furnace body and the substrate to be used, and the size of the heat reflector is preferably a plate-shaped exterior in a disk shape with a diameter of 50 mm or more or a polygonal shape with one side of 50 mm or more. In addition, it is preferable to make the thickness of the heat reflector as thin as possible, for example, 1 to 3.4 mm, preferably 1 to 3 mm. In addition, it is preferable to provide the reflector so that the area is as close as possible to the area of the disk shape or polygonal shape in the in-plane direction, for example, 80% or more in terms of the reflection area ratio. In addition, it is preferable to select a metal material or alloy material with a high reflectance, for example, 80% or more, as the metal material or alloy material used for the reflector. Here, the surface in the "in-plane direction" refers to the plate surface including the reflection surface of the heat reflector.

In the heat reflecting plate 100, the plate-shaped exterior 1 preferably has a laminated plate structure in which the first exterior plate 1a and the second exterior plate 1b are arranged opposite each other and their peripheral portions are continuously joined in a ring shape along the periphery. In FIG. 2, the first exterior plate 1a and the second exterior plate 1b form a laminated plate structure by the joint 2 between their peripheral portions. As shown in FIG. 1, the joint 2 between the peripheral portions is continuous in a ring shape along the periphery of the plate-shaped exterior 1. In FIG. 1, the joint 2 between the peripheral portions can be seen as the boundary between the first exterior plate 1a and the second exterior plate 1b when viewed through the second exterior plate 1b, and is illustrated as a gray area. By using a laminated plate structure, the plate-shaped exterior can be made thinner, thereby reducing the heat capacity.

The shape of the plate-shaped exterior 1 when the reflector 5 is viewed from the front is, for example, circular, elliptical, rectangular, or square, and a circular shape is preferable. In addition, the outer plate surface of the silica plate 1 when the reflector 5 is viewed from the front is preferably a flat surface without through holes or unevenness. The diameter of the circle is, for example, 5 to 50 cm. The width of the annular shape of the joint 2 between the peripheral portions is, for example, 0.5 to 20 mm. The thickness of the plate-shaped exterior 1 is preferably 1 to 3.4 mm, and more preferably 1 to 3 mm. The thickness of the first exterior plate 1a is preferably 0.1 to 1.7 mm, and more preferably 0.5 to 1.5 mm. The thickness of the second exterior plate 1b is preferably 0.1 to 1.7 mm, and more preferably 0.5 to 1.5 mm. The reflection area ratio of the reflector 5 to the plate surface of the plate-shaped exterior 1 when the reflector 5 is viewed from the front is preferably 80% or more, more preferably 87% or more, and even more preferably 90% or more.

The material of the plate-shaped exterior 1 is preferably silica or silicon. Silica is preferred because of its material strength and ability to transmit infrared rays without absorbing them, while silicon is preferred because of its small heat capacity. Silica includes forms in which it is crystalline silica or amorphous silica. The impurity concentration of the plate-shaped exterior 1 is 100 ppm or less, preferably 90 ppm or less. Note that this embodiment includes a form in which the material of the plate-shaped exterior 1 is silicon, and the surface of the silicon is oxidized to silica.

In the heat reflecting plate 100, the laminated plate structure has a cavity 12 provided between the opposing surfaces of the first exterior plate 1a and the second exterior plate 1b, and is sealed by the joint 2 between the peripheral portions on at least one of the first exterior plate 1a side and the second exterior plate 1b side, and it is preferable that the reflector 5 is disposed in the cavity 12. The cavity 12 may be provided on the first exterior plate 1a side, on both the first exterior plate 1a side and the second exterior plate 1b side, or on the second exterior plate 1b side. FIG. 2 shows a form in which the cavity 12 is provided on the first exterior plate 1a side. In this form, a recess is provided on one surface of the first exterior plate 1a, and the second exterior plate 1b is a flat plate without a recess, and the cavity 12 is provided on the first exterior plate 1a side by forming a laminated plate structure of the first exterior plate 1a and the second exterior plate 1b. As a result, the cavity 12 is provided only on the first exterior plate 1a side of the opposing surfaces of the first exterior plate 1a and the second exterior plate 1b, and is sealed by the joint 2 between the peripheral edges. Because the reflector 5 is inside the cavity 12, which is an enclosed space, the joint between the peripheral edges is less susceptible to stress in the direction of peeling caused by the reflector, and contamination inside the furnace due to damage to the reflector can be suppressed. Furthermore, damage due to the difference in thermal expansion between the plate-shaped exterior and the reflector can be avoided.

Figure 3 shows a form in which the cavity 12 is provided across both the first exterior plate 1a side and the second exterior plate 1b side. In this form, a recess is provided on one surface of the first exterior plate 1a, and a recess is provided on one surface of the second exterior plate 1b, and the first exterior plate 1a and the second exterior plate 1b are structured as a mating plate so that the recesses fit together. As a result, the cavity 12 is provided on both the first exterior plate 1a side and the second exterior plate 1b side of the opposing surfaces of the first exterior plate 1a and the second exterior plate 1b.

Figure 4 shows a form in which the cavity 12 is provided on the second exterior plate 1b side. In this form, the first exterior plate 1a is a flat plate with no recesses, one surface of the second exterior plate 1b is provided with a recess, and the first exterior plate 1a and the second exterior plate 1b are structured as a laminated plate, so that the cavity 12 is provided on the second exterior plate 1b side. As a result, the cavity 12 is provided only on the second exterior plate 1b side of the opposing surfaces of the first exterior plate 1a and the second exterior plate 1b.

The height of the cavity 12 (length in the vertical direction in FIG. 2) is preferably 0.1 μm to 5 mm, and more preferably 0.1 μm to 1 mm. There are three forms of the cavity 12: a form in which a recess is provided only on the first exterior plate 1a side, a form in which a recess is provided on both the first exterior plate 1a side and the second exterior plate 1b side, and a form in which a recess is provided only on the second exterior plate 1b side. In any form, the recess forms a bank portion 11 on the peripheral portion of the first exterior plate 1a and/or the peripheral portion of the second exterior plate 1b. In the form of FIG. 2, the top surface of the bank portion 11 formed on the first exterior plate 1a is joined to the flat plate portion of the second exterior plate 1b arranged opposite to each other, forming a joint portion 2 between the peripheral portions. In the form of FIG. 3, the top surfaces of the bank portions 11 of the first exterior plate 1a and the second exterior plate 1b are joined to each other, forming a joint portion 2 between the peripheral portions. In the embodiment shown in FIG. 4, the top surface of the bank portion 11 formed on the second exterior plate 1b is joined to the flat portion of the first exterior plate 1a arranged opposite to it, forming a joint portion 2 between the peripheral portions. The recess can be formed, for example, by an etching method.

In the heat reflecting plate 100 according to this embodiment, as shown in FIG. 2, the first exterior plate 1a has a bank portion 11 provided on the peripheral portion and a recessed portion that is surrounded by the bank portion 11 and forms a cavity 12, and the second exterior plate 1b is preferably flat. By providing a recessed portion only in the first exterior plate 1a, the cavity 12 can be provided in the plate-like exterior with a simple structure. Heat reflecting plates having such a configuration include the heat reflecting plates 103, 106, 109, and 112 illustrated in FIG. 5, FIG. 8, FIG. 12, and FIG. 15, in addition to the heat reflecting plate shown in FIG. 2.

In the heat reflecting plate 102 according to this embodiment, as shown in FIG. 4, it is preferable that the first exterior plate 1a is flat, and the second exterior plate 1b has a bank portion 11 provided on the periphery and a recess that is surrounded by the bank portion 11 and forms a cavity 12. By providing a recess only in the second exterior plate 1b, the cavity 12 can be provided in the plate-like exterior with a simple structure. Examples of heat reflecting plates having this type of configuration include the heat reflecting plates 105, 108, and 111 shown in FIG. 4, as well as FIG. 7, FIG. 11, and FIG. 14.

As shown in FIG. 2 or FIG. 3, the heat reflecting plate 100, 101 according to this embodiment has a cavity 12 at least on the first exterior plate 1a side, and has a thin film formed as a reflector 5 on the surface inside the cavity 12 of the first exterior plate 1a. The thin film is a laminated film having, in order from the surface side inside the cavity 12 of the first exterior plate 1a, a base film 3 and a reflective film 4 as a surface layer including a reflective surface. The base film 3 is made of Ta, Mo, Ti, Zr, Nb, Cr, W, Co, or Ni, or Ta, Mo, Ti, Zr, Nb, C The first exterior plate is made of an alloy containing at least one selected from the group consisting of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, and the reflective film 4 is made of an alloy containing at least one selected from the group consisting of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, and it is preferable that the base film 3 and the reflective film 4 have different compositions. Since the reflector is formed on the surface inside the cavity of the first exterior plate, the joint between the peripheral parts is less likely to be subjected to stress in the peeling direction caused by the reflector, and contamination inside the furnace due to damage to the reflector can be suppressed. Furthermore, damage due to the difference in thermal expansion between the plate-shaped exterior and the reflector can be avoided. When the reflector 5 is a thin film, and the thin film is a laminated film, at least the surface layer of the reflector 5, including the reflective surface, corresponds to the reflective film 4. The reflector 5, which is a laminated film, is formed on the surface inside the cavity 12 of the first exterior plate 1a, i.e., on the bottom surface of the recess. The reflector 5, which is a laminated film, is preferably formed over an area of 50 to 100% of the total area of the bottom surface of the recess, and more preferably over an area of 80 to 100%. The film thickness of the reflector 5 is preferably 10 to 1500 nm, and more preferably 20 to 400 nm.

The undercoat film 3 is preferably made of Ta, Mo, Ti, Zr, Nb, Cr, W, Co, or Ni, or an alloy containing at least one selected from the group consisting of Ta, Mo, Ti, Zr, Nb, Cr, W, Co, and Ni. Such metals or alloys have a high melting point and excellent adhesion to the plate-shaped exterior. The undercoat film 3 is preferably a thin film obtained by, for example, a sputtered film, a coating film, CVD, deposition, or the like. The alloy containing at least one selected from the group consisting of Ta, Mo, Ti, Zr, Nb, Cr, W, Co, and Ni is preferably an alloy containing one of these elements in the largest amount by mass, more preferably an alloy containing 50 mass% or more of Ta, Mo, Ti, Zr, Nb, Cr, W, Co, or Ni, even more preferably an alloy containing 60 mass% or more, and most preferably an alloy containing 70 mass% or more, such as a Ta-Mo alloy, a Ta-Cr alloy, or a Cr-Co alloy. The thickness of the undercoat film 3 is preferably 5 to 500 nm, and more preferably 10 to 100 nm. The undercoat film 3 improves the adhesion of the reflective film 4.

The reflective film 4 is preferably deposited on the surface of the undercoat film 3. The reflective film 4 is preferably made of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, or an alloy containing at least one selected from the group consisting of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu. Such metals or alloys have a high melting point and a high infrared reflectance. They also have low reactivity with the undercoat film. The reflective film 4 is preferably a thin film obtained by, for example, a sputtered film, a coating film, CVD, deposition, or the like. The alloy containing at least one selected from the group consisting of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu is preferably an alloy containing one of these elements in the largest amount by mass, more preferably an alloy containing 50% or more by mass of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, even more preferably an alloy containing 60% or more by mass, and most preferably an alloy containing 70% or more by mass, such as an Ir-Pt alloy, an Ir-Rh alloy, or a Pt-Ru alloy. The thickness of the reflective film 4 is preferably 5 to 1000 nm, and more preferably 10 to 300 nm.

Suitable combinations of the base film 3 and the reflective film 4 when forming a laminated film include a Ta film/Ir film, a Ta film/Pt film, and a Mo film/Ir film. The thickness of the laminated film is preferably 10 to 1500 nm, and more preferably 20 to 400 nm.

As shown in FIG. 5 or FIG. 6, the thickness of the reflector 5 may be equal to the height of the cavity 12, i.e., the reflective film 4 may be in contact with the surface of the second exterior plate 1b. Interference fringes caused by partial contact between the reflective film 4 and the second exterior plate are reduced. It is preferable that the base film 3 is deposited on the surface (bottom surface of the recess) within the cavity 12 of the first exterior plate 1a, and the reflective film 4 is deposited on the surface of the base film 3. It is preferable that the reflective film 4 is in contact with the surface of the second exterior plate 1b, but is not formed on the surface of the second exterior plate 1b, i.e. is not deposited.

As shown in FIG. 4, in the heat reflecting plate 102 according to this embodiment, the first exterior plate 1a is a flat plate, has a cavity 12 on the second exterior plate 1b side, and has a thin film formed as a reflector 5 on the surface of the first exterior plate 1a. The thin film is a laminated film having, in order from the surface side of the first exterior plate 1a, a base film 3 and a reflective film 4 as a surface layer including a reflective surface. The base film 3 is made of Ta, Mo, Ti, Zr, Nb, Cr, W, Co, or Ni, or Ta, Mo, Ti, Zr, N The reflective film 4 is preferably made of an alloy containing at least one selected from the group consisting of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, or an alloy containing at least one selected from the group consisting of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu. The embodiment shown in FIG. 4 differs from the embodiment shown in FIG. 2 or FIG. 3 in that the first exterior plate 1a is a flat plate and has a cavity 12 on the second exterior plate 1b side, but is otherwise similar. Since a thin film as a reflector is formed on the first exterior plate 1a, which is a flat plate, a heat reflector with excellent productivity can be obtained.

As shown in FIG. 7, the thickness of the reflector 5 may be equal to the height of the cavity 12, that is, the reflective film 4 may be in contact with the surface of the second exterior plate 1b (the bottom surface of the recess). The interference fringes caused by partial contact between the reflective film 4 and the second exterior plate are reduced. The base film 3 is preferably deposited on the surface of the first exterior plate 1a, and the reflective film 4 is preferably deposited on the surface of the base film 3. The form shown in FIG. 7 differs from the form shown in FIG. 5 or FIG. 6 in that the first exterior plate 1a is a flat plate and has the cavity 12 on the second exterior plate 1b side, but is otherwise similar. Since a thin film is formed as a reflector on the first exterior plate 1a, which is a flat plate, a heat reflector with excellent productivity can be obtained.

As shown in FIG. 8 and FIG. 10 to FIG. 14, the heat reflecting plates 106 to 111 according to this embodiment preferably have at least one support 6 that stands between the opposing surfaces of the laminated plate structure in the cavity 12. The support 6 can increase the bonding strength of the laminated plate structure. As shown in FIG. 8 or FIG. 12, for example, the support 6 extends from the bottom surface of the recess of the first exterior plate 1a, and the top surface of the support 6 is bonded to the surface of the flat second exterior plate 1b. In order to make the support 6 extend only from the bottom surface of the recess of the first exterior plate 1a, for example, the bank portion 11 is formed by forming a recess by etching only the first exterior plate 1a, but in this case, the support 6 can be formed as a non-etched portion in the same way as the bank portion 11 is made as a non-etched portion. In addition, as shown in FIG. 10 or 13, the support portion 6 may extend from the bottom surface of the recess of the first exterior plate 1a and from the bottom surface of the recess of the second exterior plate 1b, and the top surfaces of the support portion 6 may be joined together. In order to form the support portion 6 to extend from both the bottom surface of the recess of the first exterior plate 1a and the bottom surface of the recess of the second exterior plate 1b, for example, the bank portion 11 may be formed by forming a recess in the first exterior plate 1a and the second exterior plate 1b by etching, and at this time, the support portion 6 may be formed as a non-etched portion in the same manner as the bank portion 11 is formed as a non-etched portion. In addition, as shown in FIG. 11 or 14, the support portion 6 may extend from the bottom surface of the recess of the second exterior plate 1b, and the top surface of the support portion 6 may be joined to the surface of the flat first exterior plate 1a. In order to make the support portion 6 extend only from the bottom surface of the recess in the second exterior plate 1b, for example, the bank portion 11 can be formed by forming a recess only in the second exterior plate 1b by etching, and the support portion 6 can be left as a non-etched portion. In the figure, the joint between the support portion 6 and the first exterior plate 1a or the second exterior plate 1b, or the joint between the support portions 6, is indicated by joint 7.

The heat reflectors 106-111 shown in Figures 8 and 10-14 are similar to the heat reflectors 100-105 shown in Figures 2-7 in terms of the reflectors 5. In this case, it is preferable that the reflector 5 formed on the outside of the support 6 does not have through holes or irregularities, and that the inner periphery of the reflector outside the support 6 and the entire surface surrounded by the periphery of the reflector are reflective surfaces.

Next, the shape of the support 6 will be described. In the heat reflectors 106 to 111 according to this embodiment, the support 6 includes a form in which it is columnar or cylindrical. The cross-sectional shape of the main axis of the support 6 is preferably a circle, an ellipse, or a polygon with a triangle or more. In the case of a polygon with a triangle or more, it is preferably a square or a regular hexagon. Furthermore, as shown in FIG. 9, the heat reflector preferably has a plurality of support parts 6, the support parts 6 are cylindrical, and each support part 6 has a three-dimensional space-filling structure in which they share a part of the cylindrical wall with each other. By adopting a three-dimensional space-filling structure, it is possible to increase the bonding strength while widening the area of the reflector, and further increase the strength of the reflector itself. The three-dimensional space-filling structure includes a honeycomb structure, a rectangular lattice structure, a square lattice structure, or a rhombic lattice structure. FIG. 9 illustrates a heat reflector 100 having a support part of a honeycomb structure. The honeycomb structure is a structure in which hexagonal cylinders are arranged without gaps, preferably a structure in which regular hexagonal cylinders are arranged without gaps. The rectangular lattice structure is a structure in which angular tubular shapes with a rectangular cross section are arranged without gaps. The square lattice structure is a structure in which angular tubular shapes with a square cross section are arranged without gaps. The diamond lattice structure is a structure in which angular tubular shapes with a diamond cross section are arranged without gaps. Here, when forming the reflector 5 inside the cylindrical support part 6 of the three-dimensional space-filling structure, it is preferable that the entire surface surrounded by the periphery of the reflector inside the cylindrical support part 6 is a reflective surface without providing through holes or irregularities in the formed reflector 5.

In the heat reflecting plate according to this embodiment, as shown in FIG. 20, the opposing surfaces of the first exterior plate 1a and the second exterior plate 1b are flat surfaces, and the reflector 5 is a thin film formed on the surface of the first exterior plate 1a on the second exterior plate 1b side in the inner area of the annular joint 2 between the peripheral portions. The thin film is a laminated film having, in order from the surface side of the first exterior plate 1a, a base film and a reflective film as a surface layer including a reflective surface. The base film is made of Ta, Mo, Ti, Zr, Nb, Cr, W, Co or Ni, or Ta, Mo, Ti, Zr , Nb, Cr, W, Co and Ni, and the reflective film is made of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag or Cu, or made of an alloy containing at least one selected from the group consisting of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag or Cu, and it is preferable that the base film and the reflective film have different compositions. Note that in FIG. 20, the illustration of the form in which the reflector 5 is a laminated film is omitted. The base film is preferably deposited on the surface of the first exterior plate, and the reflective film is preferably deposited on the surface of the base film. It is preferable that the reflective film is in contact with the surface of the second exterior plate, but is not formed on the surface of the second exterior plate, i.e., is not deposited. Such a structure allows for a heat reflector with excellent productivity. In addition, the reflector can be attached to the second exterior plate, further suppressing interference fringes. The thickness of the laminated film is preferably 10 to 500 nm. By reducing the thickness of the laminated film, even if a cavity 12 is not provided, a ring-shaped joint can be formed between the peripheral portions due to stress deformation of the first exterior plate and the second exterior plate, and the laminated film can be completely covered by the plate-shaped exterior. The reason for selecting the metal or alloy for the reflector 5 is the same as for the heat reflectors 100 to 105 shown in Figures 2 to 7.

(Mode 1) in which the thin film formed as the reflector is a specified metal film or an alloy film containing a specified metal)
The heat reflecting plate of this embodiment has a cavity at least on the first exterior plate side, and has a thin film formed as a reflector on the surface within the cavity of the first exterior plate, and the thin film is preferably a film made of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag or Cu, or an alloy film containing 50 mass% or more of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag or Cu. When the thin film formed as a reflector is a film made of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, or an alloy film containing 50 mass % or more of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, the thin film formed as a reflector may be a single layer film. The heat reflector according to the present embodiment has a structure in which the reflector 5, which is a laminated film, in Fig. 2, Fig. 5, Fig. 8 or Fig. 12 is replaced with a film made of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag or Cu, or an alloy film containing 50 mass% or more of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag or Cu. Also, as in the plate-shaped exterior 1 in Fig. 3, Fig. 6, Fig. 10 or Fig. 13, the cavity 12 may be provided on both sides of the first exterior plate 1a side and the second exterior plate 1b side. In this embodiment, a recess is provided on one surface of the first exterior plate 1a, a recess is provided on one surface of the second exterior plate 1b, and the first exterior plate 1a and the second exterior plate 1b are structured as a mating plate so that the recesses fit together. As a result, the cavity 12 is provided on both the first exterior plate 1a side and the second exterior plate 1b side of the opposing surfaces of the first exterior plate 1a and the second exterior plate 1b. Note that the incident direction of infrared rays on the heat reflecting plate according to this embodiment may be either from top to bottom or from bottom to top.

(Mode 2 in which the thin film formed as the reflector is a specified metal film or an alloy film containing a specified metal)
In the heat reflecting plate of this embodiment, the first exterior plate is a flat plate, has a cavity on the second exterior plate side, and has a thin film formed on the surface of the first exterior plate as a reflector, and the thin film is preferably a film made of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag or Cu, or an alloy film containing 50 mass% or more of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag or Cu. When the thin film formed as a reflector is a film made of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, or an alloy film containing 50 mass % or more of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, the thin film formed as a reflector may be a single layer film. The heat reflector according to this embodiment has a structure in which the reflector 5, which is a laminated film, in Fig. 4, Fig. 7, Fig. 11 or Fig. 14 is replaced with a film made of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag or Cu, or an alloy film containing 50 mass% or more of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag or Cu. The incident direction of infrared rays on the heat reflector according to this embodiment may be either from top to bottom or from bottom to top.

(Mode 3) The thin film formed as the reflector is a predetermined metal film or an alloy film containing a predetermined metal.
In the heat reflecting plate of this embodiment, the opposing surfaces of the first and second exterior plates are flat surfaces, and the reflector is a thin film formed on the surface of the first exterior plate on the second exterior plate side, in the inner area of the annular joint between the peripheral portions, and the thin film is preferably a film made of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag or Cu, or an alloy film containing 50 mass% or more of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag or Cu. When the thin film formed as a reflector is a film made of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, or an alloy film containing 50 mass % or more of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, the thin film formed as a reflector may be a single layer film. The heat reflector according to this embodiment has a structure in which the reflector 5 in Fig. 20 is replaced with a film made of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, or an alloy film containing 50 mass% or more of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu. The incident direction of infrared rays on the heat reflector according to this embodiment may be either from top to bottom or from bottom to top.

(Mode 4) The thin film formed as the reflector is a predetermined metal film or an alloy film containing a predetermined metal.
The heat reflecting plate of this embodiment has a cavity on the first exterior plate side and the second exterior plate side, and has a thin film formed as a reflector on the surface within the cavity of the first exterior plate, and the thin film is preferably a film made of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag or Cu, or an alloy film containing 50 mass% or more of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag or Cu. When the thin film formed as a reflector is a film made of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, or an alloy film containing 50 mass % or more of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, the thin film formed as a reflector may be a single layer film. The heat reflector according to this embodiment has a structure in which the reflector 5, which is a laminated film, in Fig. 3, Fig. 6, Fig. 10 or Fig. 13 is replaced with a film made of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag or Cu, or an alloy film containing 50 mass% or more of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag or Cu. The incident direction of infrared rays on the heat reflector according to this embodiment may be either from top to bottom or from bottom to top.

In forms 1 to 4, in an alloy film containing 50% by mass or more of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, the content of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. A film made of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, or an alloy film containing 50 mass% or more of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu is preferably formed with a film thickness similar to that of the reflector 5, which is a laminated film, and the area ratio of the thin film formed on the bottom surface of the recess is preferably formed in the same range as that of the reflector 5, which is a laminated film.

In the heat reflector according to this embodiment, the joint 2 between the peripheral portions is preferably a surface activated joint. Furthermore, the joint 7 including the support portion 6 is preferably a surface activated joint. Since the joint can be performed at a relatively low temperature, the joint can be performed without thermal or physical damage to the reflective film. In addition, by performing the joint while maintaining the inside in a vacuum, the joint strength at the joint is increased, the heat reflector has a longer life, the corrosion resistance is increased, and contamination inside the furnace is suppressed. The surface activated joint refers to a part where at least one of the parts to be joined is made surface activated, and then the joint parts are pressed together to integrate the surface structure at the atomic level and joined. It is more preferable to make both of the parts to be joined surface activated and then press the joint parts together. In the joint between plate-shaped exteriors, a silicon film may be formed, then the surface may be activated, and then the joint parts may be pressed together. There are room temperature activated joints and plasma activated joints. Room temperature activated bonding sections include, for example, bonding sections that are bonded by surface activation using a high-speed atomic beam, bonding sections that are bonded by forming a nano-adhesive layer using an active metal such as Si and surface activation, and bonding sections that are bonded by surface activation using an ion beam. Plasma activated bonding sections include, for example, bonding sections that are bonded by surface activation using oxygen plasma, and bonding sections that are bonded by surface activation using nitrogen plasma. By making the bonding section 2 between the peripheral parts a surface activated bonding section, leakage at the bonding section can be reduced, and for example, by maintaining the cavity in a vacuum, damage to the plate-shaped exterior due to an increase in internal pressure at high temperatures can be prevented. For methods of forming surface activated bonding sections, see, for example, Patent Documents 4 to 6.

In the heat reflector according to this embodiment, the pressure inside the cavity 12 is preferably reduced to less than atmospheric pressure. The pressure inside the cavity 12 is more preferably 10 ⁻² Pa or less. This can prevent the internal pressure of the cavity 12 from increasing during heat treatment, and can further prevent contamination inside the furnace. In addition, deterioration of the reflective film at high temperatures can be prevented.

(Reflector is a plate)
In the heat reflecting plate 112 according to this embodiment, as shown in FIG. 15 , it is preferable that the reflector 8 is a plate and is made of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag or Cu, or an alloy containing at least one selected from the group consisting of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag or Cu. As the alloy containing at least one selected from the group consisting of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, it is preferable to use an alloy containing any one of these elements in the largest amount by mass, more preferably an alloy containing 50% by mass or more of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, even more preferably an alloy containing 60% by mass or more, and most preferably an alloy containing 70% by mass or more, such as an Ir-Pt alloy, an Ir-Rh alloy, or a Pt-Ru alloy. The plate as a reflector is accommodated in the cavity 12, and corrosion of the plate is unlikely to occur. Furthermore, the joint between the peripheral portions is unlikely to be subjected to stress in the peeling direction caused by the plate. The reflector 8, which is a plate, is preferably formed with an area of 50 to 100% of the total area of the bottom surface of the recess, and more preferably with an area of 80 to 100%. Even in the embodiment in which the reflector is a plate, the heat reflecting plate 112 has a total heat capacity in the thickness direction of the plate-like exterior and the reflector per ¹ mm2 of 0.0004 to 0.0080 (J/K), preferably 0.0023 to 0.0070 (J/K), and more preferably 0.0030 to 0.0060 (J/K).

(Reflector is foil)
In the heat reflector of this embodiment, it is preferable that the reflector is a foil and is made of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag or Cu, or is made of an alloy containing at least one selected from the group consisting of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag or Cu (not shown). As the alloy containing at least one selected from the group consisting of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, it is preferable to use an alloy containing any one of these elements in the largest amount by mass, more preferably an alloy containing 50 mass% or more of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge, Au, Ag, or Cu, more preferably an alloy containing 60 mass% or more, and most preferably an alloy containing 70 mass% or more, such as an Ir-Pt alloy, an Ir-Rh alloy, or a Pt-Ru alloy. In FIG. 15, the reflector 8 is in a state where a foil is housed in the cavity 12 instead of a plate, and the foil is less likely to corrode. Furthermore, the joint between the peripheral portions is less likely to be subjected to stress in the peeling direction caused by the foil. The foil reflector is preferably formed with an area of 50 to 100% of the total area of the bottom surface of the recess, and more preferably with an area of 80 to 100%. Even in the embodiment in which the reflector is a foil, the heat reflector 112 has a total heat capacity in the thickness direction of the plate-like exterior and the reflector per ¹ mm2 of 0.0004 to 0.0080 (J/K), preferably 0.0023 to 0.0070 (J/K), and more preferably 0.0030 to 0.0060 (J/K).

In the heat reflector according to this embodiment, the thickness of the reflector is preferably 0.01 μm to 5 mm, and more preferably 0.02 μm to 2 mm. The heat capacity of the heat reflector can be reduced while maintaining the high reflection efficiency of the reflector. If the thickness of the reflector is less than 0.01 μm, it becomes difficult to maintain the reflection efficiency, and if it exceeds 5 mm, the heat amount of the reflector may become too large. If the reflector is a thin film, the thickness of the laminated film is preferably 10 nm to 1500 nm, and more preferably 20 nm to 400 nm. If the reflector is a plate, the plate thickness is preferably 0.5 mm to 5.0 mm, and more preferably 0.5 mm to 2.0 mm. If the reflector is a foil, the thickness of the foil is preferably 3 μm to 2.0 mm, and more preferably 8 μm to 1.0 mm.

In this embodiment, when a cavity is present, the value obtained by subtracting the thickness of the reflector from the height of the cavity (the length in the vertical direction in FIG. 2), i.e., the heightwise gap within the cavity, is preferably 200 μm or less, and more preferably 100 μm or less. If the heightwise gap within the cavity exceeds 200 μm, the deformation of the plate-like exterior due to atmospheric pressure will become large, and as a result, the stress applied near the joint will become large, which may cause the joint to crack.

In Figures 2 to 8 and Figures 10 to 14, the infrared rays are incident from top to bottom. In Figure 15, the infrared rays may be incident from top to bottom or bottom to top. In a heat treatment device, a heat retainer is necessary to maintain the temperature of the substrate to be heated, but a heat retainer for the heat reflector of this embodiment is not necessarily required. In the absence of a heat retainer, the heat reflector of this embodiment does not delay the heating and cooling response in a heat treatment process having a temperature rise profile to the heat treatment temperature, a temperature maintenance profile, and a temperature drop profile, and makes it difficult for deviations to occur from each desired profile, and also does not prolong the time required for one heat treatment cycle, resulting in no decrease in production efficiency.

The present invention will be described in more detail below with reference to examples, but the present invention should not be construed as being limited to these examples.

(Comparative Example 1)
First, an opaque quartz with a circumference of 300 mm and a thickness of 4.0 mm was prepared. Next, the reflectance of the opaque quartz was measured using an ultraviolet-visible spectrophotometer (Shimadzu Corporation, model: UV-3100PC). The measured reflectance results are shown in FIG. 21. It was confirmed that the opaque quartz in this comparative example had a reflectance of 5% or less at wavelengths of 2000 nm or more at 1000°C. At this time, the total thickness of the heat reflector in Comparative Example 1 was 4.0000 mm, and the reflection area ratio was 100.00%. Next, the total heat capacity of the plate thickness exterior and the reflector in the thickness direction in ¹ mm2 of the opaque quartz was calculated to be 0.0092 (J/K).

Example 1
(An embodiment in which the reflector is a laminated film)
The heat reflector shown in FIG. 2 is manufactured. First, two plate-shaped exterior plates with an outer circumference of 300 mm and a thickness of 1.2 mm are prepared, and are designated as the first exterior plate and the second exterior plate, respectively. Next, a width of 10 mm from the outer circumference of the first exterior plate is left as a joint with the second exterior plate, and the other parts are etched to provide a recess for a cavity with a depth of 1 μm. Next, a Ta film of 50 nm is formed by sputtering on the bottom surface of the recess of the first exterior plate as a base film, and a Ir film of 150 nm is formed by sputtering on the base film as a reflective film to form a reflector. Next, the reflectance of the reflector is measured using an ultraviolet-visible spectrophotometer (manufactured by Shimadzu Corporation, model: UV-3100PC). The measured reflectance is shown in FIG. 16. The measurement was performed by directly applying light for measurement to the surface of the reflector. In addition, the relationship between the wavelength and the radiation amount of blackbody radiation emitted by a material at 1000° C. is calculated using (Equation 1). The calculation result is shown in FIG. 17.
Here, h is Planck's constant (6.62607015×10 ⁻³⁴ J·s), k _B is Boltzmann's constant (1.380649×10 ⁻²³ J/K), c is the speed of light (299792458 m/s), and λ is the wavelength (nm). From the results of FIG. 17, it can be confirmed that it is necessary to reflect radiant heat at 1000° C., and that the amount of radiation is large at wavelengths of 2000 nm to 2600 nm. Also, from the results of FIG. 16, it can be confirmed that at 1000° C., the reflector in this embodiment has a reflectance of 90% or more at wavelengths of 2000 nm or more. Next, in order to bond the first exterior plate on which the reflector is formed and the flat second exterior plate, a high-speed atomic beam is irradiated to the joint of the first exterior plate in a vacuum of 10 ⁻² Pa or less to activate the surface, and the second exterior plate is pressed against the first exterior plate to produce a heat reflector. At this time, the overall thickness of the heat reflector in Example 1 was 2.4000 mm, and the reflection area ratio was 93.33%. After the heat reflector was produced, the total heat capacity of the plate thickness exterior and the reflector in the thickness direction per ¹ mm2 was calculated to be 0.0055 (J/K). Since the amount of heat required to heat the heat reflector to 1000°C is proportional to the heat capacity, the heat reflector in Example 1 had higher heat reflectivity than the opaque quartz in Comparative Example 1, and was able to reduce power consumption by 40.22%.

Example 2
(An embodiment in which the reflector is a laminated film)
First, two plate-shaped exteriors with an outer circumference of 300 mm and a thickness of 1.2 mm were prepared, and were designated as the first exterior plate and the second exterior plate, respectively. Next, a width of 5 mm from the outer circumference of the first exterior plate was masked as a joint with the second exterior plate. Next, a 50 nm thick Ta film was formed on the masked surface of the first exterior plate by sputtering as a base film, and a 150 nm thick Ir film was formed on the base film by sputtering as a reflective film to form a reflector. Next, the masking was removed. The reflector was the same as the reflector in Example 1, and had the same reflection characteristics as those shown in FIG. 16. Next, in order to join the flat first exterior plate on which the reflector was formed and the flat second exterior plate, a high-speed atomic beam was irradiated to the joint of the first exterior plate in a vacuum of a vacuum degree of 10 ^-2 Pa or less to activate the surface, and the second exterior plate was pressed against the first exterior plate to produce a heat reflector. At this time, the thickness of the entire heat reflector in Example 2 was 2.4002 mm, and the reflection area ratio was 96.67%. After preparing the heat reflector, the total heat capacity of the plate thickness exterior and the reflector in the thickness direction per ¹ mm2 was calculated to be 0.0055 (J/K). Since the amount of heat required to heat the heat reflector to 1000°C is proportional to the heat capacity, the heat reflector of Example 2 has higher heat reflectivity than the opaque quartz of Comparative Example 1 and can reduce power consumption by 40.22%.

Example 3
(An embodiment in which the reflector is a laminated film)
First, two plate-shaped exteriors with an outer circumference of 300 mm and a thickness of 1.2 mm were prepared, and were designated as the first exterior plate and the second exterior plate, respectively. Next, a width of 5 mm from the outer circumference of the first exterior plate was masked as a joint with the second exterior plate. Next, a 50 nm thick Ta film was formed on the masked surface of the first exterior plate by sputtering as a base film, and a 150 nm thick Ir film was formed on the base film by sputtering as a reflective film to form a reflector. Next, the masking was removed. The reflector was the same as the reflector in Example 1, and had the same characteristics as the reflection characteristics shown in FIG. 16. Next, in order to bond the flat first exterior plate on which the reflector was formed and the flat second exterior plate, oxygen plasma was brought into contact with the joint of the first exterior plate to activate the surface, and the second exterior plate was pressed against the first exterior plate to produce a heat reflector. At this time, the thickness of the entire heat reflector in Example 3 was 2.4002 mm, and the reflection area ratio was 96.67%. After preparing the heat reflector, the total heat capacity of the plate-shaped exterior and the reflector in the thickness direction per ¹ mm2 was calculated to be 0.0055 (J/K). Since the amount of heat required to heat the heat reflector up to 1000°C is proportional to the heat capacity, the heat reflector of Example 3 has higher heat reflectivity than the opaque quartz of Comparative Example 1 and can reduce power consumption by 40.22%.

Example 4
(The reflector is a laminated film and has honeycomb-shaped support sections.)
The heat reflector shown in FIG. 12 is produced. First, two plate-shaped exteriors with an outer circumference of 300 mm and a thickness of 1.2 mm are prepared, and are respectively used as the first exterior plate and the second exterior plate. Next, a width of 10 mm is masked from the outer circumference of the first exterior plate, and then, in other places, masking is performed on the places corresponding to the honeycomb-shaped support part with a width of 10 mm (the length of one side is 5.77 mm) and a wall column thickness of 0.3 mm, and then etching is performed to provide a recess for a cavity with a depth of 1 μm. Next, a Ta film of 50 nm is formed by sputtering on the bottom surface of the masked recess of the first exterior plate as a base film, and a Ir film of 150 nm is formed by sputtering on the base film as a reflective film to form a reflector. Next, the masking is removed. The reflector of this embodiment is the reflector of Example 1 with a honeycomb structure. The reflectance shown in FIG. 16 indicates the value of the form in which the entire surface is a reflecting film, and since the reflecting film having a honeycomb structure of this embodiment has an area ratio of the reflecting film portion to the entire surface of 94.34%, the reflection characteristic of this embodiment is considered to have a reflectance multiplied by 0.9434 with respect to the reflectance shown in FIG. 16. Next, in order to bond the first exterior plate on which the reflector is formed and the flat second exterior plate, a fast atomic beam is irradiated to the joint portion 2 and the support portion of the first exterior plate in a vacuum of 10 ^-2 Pa or less to activate the surface, and the second exterior plate is pressed against the first exterior plate to bond them, thereby producing a heat reflecting plate. At this time, the total thickness of the heat reflecting plate in Example 4 was 2.4000 mm, and the reflection area ratio was 88.05%. After producing the heat reflecting plate, the total heat capacity of the plate-shaped exterior and the reflector in the thickness direction per 1 mm ² was calculated to be 0.0055 (J/K). Since the amount of heat required to heat the heat reflector to 1000°C is proportional to the heat capacity, the heat reflector of Example 4 has higher heat reflectivity than the opaque quartz of Comparative Example 1 and was able to reduce power consumption by 40.22%.

Example 5
(An embodiment in which the reflector is Pt foil)
The heat reflector shown in FIG. 15 is prepared. First, two plate-shaped exterior plates with an outer circumference of 300 mm and a thickness of 1.2 mm are prepared, and are respectively used as the first exterior plate and the second exterior plate. Next, a width of 7 mm from the outer circumference of the first exterior plate is left as a joint with the second exterior plate, and the other parts are cut to provide a recess for a cavity with a depth of 0.2 mm. Next, a Pt foil with an outer circumference of 284 mm and a thickness of 100 μm is placed on the bottom surface of the recess of the first exterior plate to form a reflector. Next, the reflectance of the reflector is measured using an ultraviolet-visible spectrophotometer (manufactured by Shimadzu Corporation, model: UV-3100PC). The measured reflectance is shown in FIG. 18. The measurement was performed by directly applying light for measurement to the surface of the reflector. As a result of FIG. 18, it was confirmed that the reflector in this embodiment has a reflectance of 80% or more at wavelengths of 2000 nm or more at 1000° C. Next, in order to bond the first exterior plate on which the reflector is arranged to the flat second exterior plate, a high-speed atomic beam is irradiated to the joint of the first exterior plate in a vacuum of ^10-2 Pa or less to activate the surface, and the second exterior plate is pressed against the first exterior plate to bond them, thereby producing a heat reflector. At this time, the total thickness of the heat reflector in Example 5 was 2.4000 mm, and the reflection area ratio was 95.33%. After producing the heat reflector, the total heat capacity of the plate-shaped exterior and the reflector in the thickness direction per 1 ^mm2 was calculated to be 0.0056 (J/K). Since the amount of heat required to heat the heat reflector to 1000°C is proportional to the heat capacity, the heat reflector of Example 5 has higher heat reflectivity than the opaque quartz of Comparative Example 1, and can reduce power consumption by 39.13%.

Example 6
(Reflector is Mo film)
First, two plate-shaped exteriors with an outer circumference of 300 mm and a thickness of 1.2 mm were prepared, and were designated as the first exterior plate and the second exterior plate, respectively. Next, a 5 mm width from the outer circumference of the first exterior plate was masked as a joint with the second exterior plate. Next, a 200 nm Mo film was formed as a reflector on the masked surface of the first exterior plate by sputtering. Next, the masking was removed. Next, the reflectance of the reflector was measured using an ultraviolet-visible spectrophotometer (manufactured by Shimadzu Corporation, model: UV-3100PC). The measured reflectance results are shown in FIG. 19. The measurement was performed by directly applying light for measurement to the surface of the reflector. In addition, as a result of FIG. 19, it was confirmed that the reflector in this embodiment had a reflectance of 80% or more at wavelengths of 2000 nm or more at 1000° C. Next, in order to bond the first exterior plate on which the reflector was formed to the flat second exterior plate, a high-speed atomic beam was irradiated to the joint of the first exterior plate in a vacuum of ^10-2 Pa or less to activate the surface, and the second exterior plate was pressed against the first exterior plate to produce a heat reflector. At this time, the total thickness of the heat reflector in Example 6 was 2.4002 mm, and the reflection area ratio was 96.67%. After the heat reflector was produced, the total heat capacity of the plate-shaped exterior and the reflector in the thickness direction per ¹ mm2 was calculated to be 0.0055 (J/K). Since the amount of heat required to heat the heat reflector to 1000°C is proportional to the heat capacity, the heat reflector of Example 6 has higher heat reflectivity than the opaque quartz of Comparative Example 1, and can reduce power consumption by 40.22%.

(Example 7)
(Reflector is Mo film, and quartz plate is 1.7 mm thick)
First, two plate-shaped exteriors with an outer circumference of 300 mm and a thickness of 1.7 mm were prepared, and were designated as the first exterior plate and the second exterior plate, respectively. Next, a width of 5 mm from the outer circumference of the first exterior plate was masked as a joint with the second exterior plate. Next, a 200 nm Mo film was formed as a reflector on the masked surface of the first exterior plate by sputtering. Next, the masking was removed. The reflector was the same as the reflector in Example 6, and had the same reflection characteristics as those shown in FIG. 19. Next, in order to join the first exterior plate on which the reflector was formed and the flat second exterior plate, a high-speed atomic beam was irradiated to the joint of the first exterior plate in a vacuum of a vacuum degree of ¹⁰ −2 Pa or less to activate the surface, and the second exterior plate was pressed against the first exterior plate to produce a heat reflector. At this time, the thickness of the entire heat reflector in Example 7 was 3.4002 mm, and the reflection area ratio was 96.67%. After preparing the heat reflector, the total heat capacity of the plate-shaped exterior and the reflector in the thickness direction per ¹ mm2 was calculated to be 0.0079 (J/K). Since the amount of heat required to heat the heat reflector to 1000°C is proportional to the heat capacity, the heat reflector of Example 7 has higher heat reflectivity than the opaque quartz of Comparative Example 1 and was able to reduce power consumption by 14.13%.

(Example 8)
(Reflector is Mo film, and quartz plate is 0.5 mm thick)
First, two plate-shaped exteriors with an outer circumference of 100 mm and a thickness of 0.5 mm were prepared, and were respectively used as the first exterior plate and the second exterior plate. Next, a width of 5 mm from the outer circumference of the first exterior plate was masked as a joint with the second exterior plate. Next, a 200 nm Mo film was formed as a reflector on the masked surface of the first exterior plate by sputtering. Next, the masking was removed. The reflector was the same as the reflector in Example 6, and had the same reflection characteristics as those shown in FIG. 19. Next, in order to join the first exterior plate on which the reflector was formed and the flat second exterior plate, a high-speed atomic beam was irradiated to the joint of the first exterior plate in a vacuum of 10 ⁻² Pa or less to activate the surface, and the second exterior plate was pressed against the first exterior plate to produce a heat reflector. At this time, the thickness of the entire heat reflector in Example 8 was 1.0002 mm, and the reflection area ratio was 90.00%. After preparing the heat reflector, the total heat capacity of the plate-shaped exterior and the reflector in the thickness direction per ¹ mm2 was calculated to be 0.0023 (J/K). Since the amount of heat required to heat the heat reflector to 1000°C is proportional to the heat capacity, the heat reflector of Example 8 has higher heat reflectivity than the opaque quartz of Comparative Example 1 and was able to reduce power consumption by 75.00%.

Reference Signs List 100 to 112 Heat reflecting plate 1 Plate-like exterior 1a First exterior plate 1b Second exterior plate 2 Joint between peripheral portions 3 Base film 4 Reflecting film 5 Reflector 6 Support portion 7 Joint including support portion 8 Reflector 11 Bank portion 12 Cavity

Claims (9)

A plate-shaped exterior;
a heat reflector including: a reflector disposed inside the plate-shaped exterior, the outer periphery of which is completely covered by the plate-shaped exterior, and which reflects infrared rays incident on one surface of the plate-shaped exterior,
The plate-like exterior has a laminated plate structure having a joint in which a flat surface of a flat first exterior plate and a flat surface of a flat second exterior plate are arranged opposite each other and the peripheral portions are continuously joined in a ring shape along the peripheral portions,
the reflector is a thin film formed on an inner region of the annular joint between the peripheral portions of the flat surface of the first exterior plate,
The outer plate surfaces of the first exterior plate and the second exterior plate are flat surfaces over their entire surfaces,
The entire surface surrounded by the periphery of the thin film is a reflective surface, and
The reflector is a thin film, a plate, or a foil;
The heat reflector is characterized in that the total heat capacity of the plate-like exterior and the reflector in the thickness direction per ¹ mm2 is 0.0004 to 0.0080 (J/K). The heat reflector according to claim 1, characterized in that the thin film is a film made of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge , Ag, or Cu, or an alloy film containing 50 mass % or more of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge , Ag, or Cu, and the thin film is a single layer film. the thin film is a laminated film having, in order from the front surface side of the first exterior plate, a base film and a reflective film as a surface layer including the reflective surface;
The undercoat film is made of Ta, Mo, Ti, Zr, Nb, Cr, W, Co, or Ni, or is made of an alloy containing at least one selected from the group consisting of Ta, Mo, Ti, Zr, Nb, Cr, W, Co, and Ni,
the reflective film is made of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge , Ag, or Cu, or is made of an alloy containing at least one selected from the group consisting of Ir, Pt, Rh, Ru, Re, Hf, Mo, Al, Mg, Co, Ni, Fe, Sn, Ge , Ag , or Cu;
2. The heat reflector according to claim 1, wherein the undercoat film and the reflective film have different compositions. The heat reflector according to any one of claims 1 to 3, characterized in that the joint is a joint in which the flat surface of the flat first exterior plate and the flat surface of the flat second exterior plate are arranged opposite each other without providing a cavity in the first exterior plate and the second exterior plate, and the peripheral portions are continuously joined in a ring shape along the periphery by stress deformation of the first exterior plate and the second exterior plate. The heat reflector according to any one of claims 1 to 4, characterized in that the thin film is formed on the entire area of the flat surface of the first exterior plate that is inside the annular joint between the peripheral portions. The heat reflector according to any one of claims 1 to 5, characterized in that the material of the plate-shaped exterior is silica or silicon. The heat reflector according to any one of claims 1 to 6, characterized in that the thickness of the thin film is 10 nm or more and 500 nm or less. The heat reflector according to any one of claims 1 to 7, characterized in that the joint between the peripheral edges is a surface activated joint. 9. The heat reflector according to claim 1, which is a heat reflector to be placed at a position where it is directly exposed to infrared rays from inside a furnace of a heat treatment device.