JP2017037721A - Heater unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor manufacturing apparatus which achieves high in-plane uniformity of a temperature.SOLUTION: A heater unit 10 includes: a base material 310 having a cooling passage; a heater part 320 disposed above the base material and having a heating element; and a heat insulating layer 130 disposed between the base material and the heater part. Heat conductivity of the heat insulating layer may be lower than heat conductivity of the base material. Further, the heat insulating layer may be SUS including pores. Furthermore, the heater unit may include an insulator covering a heating element, and heat conductivity of the heat insulating layer may be lower than heat conductivity of the insulator.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a heater unit. In particular, the present invention relates to a heater unit used in a semiconductor manufacturing apparatus.

  In the manufacturing process of a semiconductor device, a functional element such as a transistor element, a wiring, a resistance element, or a capacitor element is formed by forming and processing a thin film on a semiconductor substrate. As a method for forming a thin film on a semiconductor substrate, methods such as a chemical vapor deposition (CVD) method and a physical vapor deposition (PVD) method are used. As a method for processing the thin film, a method such as an ion reactive etching (RIE) method is used. In the manufacturing process of the semiconductor device, a surface treatment process such as plasma treatment is performed in addition to the thin film formation and processing.

  An apparatus used for the film forming, processing, and surface treatment steps is provided with a stage that supports a semiconductor substrate. The stage not only simply supports the semiconductor substrate but also has a function of adjusting the temperature of the semiconductor substrate according to each processing step. In order to adjust the temperature as described above, the stage is provided with a heating mechanism. In particular, in the semiconductor device described above, a ceramic heater (heater unit) made of metal or ceramics is widely used as a heating mechanism.

  In the film forming, processing, and surface treatment steps, the film quality, processed shape, and surface state are sensitively changed depending on the substrate temperature. Therefore, the heater unit is required to have high temperature in-plane uniformity. Further, the heater unit is required not only to heat the stage but also to have a function of cooling the stage. That is, the heater unit is provided with a heating mechanism and a cooling mechanism. When cooling water is used for cooling the stage, it is necessary to heat the heater while flowing the cooling water through the flow path in order to avoid boiling of the cooling water. That is, it is necessary to achieve high in-plane uniformity by heating in a state where cooling water is flowed.

  As described above, for example, a structure as shown in Patent Document 1 has been developed as a heater unit including a heating mechanism and a cooling mechanism. In the heater unit shown in Patent Document 1, a flow path is formed in a wafer holder that supports a semiconductor substrate, and the temperature of the wafer is adjusted by cooling the wafer holder by flowing a fluid through the flow path.

JP 2007-43042 A

  However, in the heater unit described in Patent Document 1, the wafer holder is made of a material having high thermal conductivity in order to enable rapid cooling. Therefore, the heat generated by the heat generating mechanism is taken away by the cooling mechanism. As a result, there is a problem that the in-plane uniformity of the heater unit deteriorates due to the influence of the position of the flow path of the cooling water. There is also a problem that the heating temperature of the stage is limited for the same reason.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a semiconductor manufacturing apparatus that has high in-plane temperature uniformity and low heating temperature.

  A heater unit according to an embodiment of the present invention includes a base material having a cooling flow path, a heater portion disposed above the base material and having a heating element, and a heat insulating layer disposed between the base material and the heater portion. And having.

  Moreover, in another aspect, the heat conductivity of a heat insulation layer may be lower than the heat conductivity of a base material.

  Moreover, in another aspect, SUS may be sufficient as a heat insulation layer.

  In another aspect, the thickness of SUS may be 1 mm or more and 10 mm or less.

  In another embodiment, the heat insulating layer has pores, and the pore content in the heat insulating layer may be 1% or more and 20% or less.

  Moreover, in another aspect, it may further have an insulator that covers the heating element, and the thermal conductivity of the heat insulating layer may be lower than the thermal conductivity of the insulator.

  In another aspect, the thermal conductivity further has a thermal diffusion layer above the heater portion, the heating element has an electrical conductor and an insulator covering the electrical conductor, and the thermal conductivity of the thermal diffusion layer is It may be higher than the thermal conductivity of the insulator.

  In another aspect, the substrate may have a thermal conductivity of 100 W / mK or more.

  In another aspect, the substrate may have a gas flow path.

  The heater unit according to the present invention can provide a semiconductor manufacturing apparatus with high in-plane temperature uniformity.

It is a top view which shows the whole structure of the heater unit which concerns on one Embodiment of this invention. It is A-A 'sectional drawing of FIG. It is sectional drawing of the heater unit which concerns on one Embodiment of this invention. It is a figure which shows what relationship the thickness of the heat insulation layer in the heater unit which concerns on one Example of this invention, and the ultimate temperature of a stage surface. It is a figure which shows which thermal temperature of the heat insulation layer in the heater unit which concerns on one Example of this invention, and the ultimate temperature of a stage surface. It is a figure which shows the electron microscope image of the heat insulation layer in the heater unit which concerns on one Example of this invention.

  Hereinafter, a heater unit according to the present invention will be described with reference to the drawings. However, the heater unit of the present invention can be implemented in many different modes and should not be construed as being limited to the description of the embodiments described below. Note that in the drawings referred to in this embodiment, the same portions or portions having similar functions are denoted by the same reference numerals, and repetitive description thereof is omitted. Further, for convenience of explanation, the description will be made using the terms “upper” or “lower”, and the upper and lower parts respectively indicate directions when the heater unit is used (when the apparatus is mounted). In addition, the drawings may be schematically represented with respect to the width, thickness, shape, and the like of each part in comparison with actual aspects for the sake of clarity of explanation, but are merely examples, and the interpretation of the present invention is not limited. It is not limited.

<First Embodiment>
The overall configuration of the heater unit according to the first embodiment of the present invention will be described with reference to FIGS. 1 and 2. The heater unit according to the first embodiment of the present invention has a heating mechanism and a cooling mechanism. The heater unit according to the first embodiment can be used for a CVD apparatus, a sputtering apparatus, a vapor deposition apparatus, an etching apparatus, a plasma processing apparatus, a measurement apparatus, an inspection apparatus, a microscope, and the like. However, the heater unit according to the first embodiment is not limited to the one used in the above apparatus, and can be used for an apparatus that needs to heat and cool the substrate.

[Configuration of Heater Unit 10]
FIG. 1 is a top view showing an overall configuration of a heater unit according to an embodiment of the present invention. 2 is a cross-sectional view taken along line AA ′ of FIG. As shown in FIGS. 1 and 2, the heater unit 10 according to the first embodiment includes a plate portion 100 and a shaft 200.

  Referring to FIG. 2, the plate unit 100 includes a first base material 110, a second base material 120, a heat insulating layer 130, a heating element 140, a first insulating layer 150, and a second insulating layer 160. The first base 110 is provided with a source connection hole 117 and a drain connection hole 119. The second substrate 120 is disposed on the first substrate 110, and the first flow path 115 is provided between the second substrate 120 and the first substrate 110. Here, in other words, the first base material 110 and the second base material 120 are referred to as the base material 310, and it can be said that the first flow path 115 is provided in the base material 310. In FIG. 2, the 1st flow path 115 is formed by joining the 1st base material 110 with a flat upper surface, and the 2nd base material 120 by which the recessed part was provided in the lower surface. The heat insulating layer 130 is disposed above the second base material 120. Here, the first flow path 115 includes a source 111 connected to the source connection hole 117 and a drain 113 connected to the drain connection hole 119. In addition, a cooling fluid is supplied to the first flow path 115. As the cooling fluid, cooling water, cooling oil, gel fluid, or the like can be used.

  The first insulating layer 150 is disposed above the heat insulating layer 130, the second insulating layer 160 is disposed above the first insulating layer 150, and the heating element 140 includes the first insulating layer 150 and the second insulating layer. 160. Here, in other words, the heating element 140, the first insulating layer 150, and the second insulating layer 160 are referred to as the heater part 320. The heating element 140 is covered with the insulator 320 (the first insulating layer 150 and the second insulating layer 160). It can be said that. In FIG. 2, the heating element 140 is covered with a first insulating layer 150 having a flat upper surface and a second insulating layer 160 having a recess on the lower surface.

  In other words, the heater unit 10 includes the base material 310 having the first flow path 115, the heater unit 320 disposed above the base material 310 and having the heating element 140, and the base material 310 and the heater unit 320. It can also be said that the heat insulating layer 130 is disposed between the two.

  The shaft 200 is provided with a source tube 211 and a drain tube 213. The source tube 211 is connected to the source 111 through the source connection hole 117, and the drain tube 213 is connected to the drain 113 through the drain connection hole 119.

  Referring to FIG. 1, the first flow path 115 is folded in a shape having corners in the folded portions 115-1 and 115-2, but is not limited to this shape. For example, the first flow path 115 may be folded back in a curved shape (R shape) at the folded portions 115-1 and 115-2. Note that the shape of the first channel 115 in a top view is not limited to the shape illustrated in FIG. 1, and may have another shape. For example, the first flow path 115 may be spiral. When the first flow path 115 is spiral, the source 111 may be provided near the center of the plate unit 100, and the drain 113 may be provided near the outer periphery of the plate unit 100.

  Although FIG. 2 illustrates the structure in which the first flow path 115 is formed by the flat upper surface of the first base material 110 and the recesses on the lower surface of the second base material 120, the structure is not limited to this. For example, a recess may be provided on the upper surface of the first base material 110, and the lower surface of the second base material 120 may be flat. Or the recessed part may be provided in both the upper surface of the 1st base material 110, and the lower surface of the 2nd base material 120. FIG. Alternatively, the first flow path 115 may be provided inside the second base material 120. When the flow path is provided inside the second base material 120, the first base material 110 can be omitted.

  2 illustrates a structure in which the heating element 140 is sandwiched between the first insulating layer 150 and the second insulating layer 160, the present invention is not limited to this structure. For example, the heating element 140 may be embedded in the first insulating layer 150.

  2 illustrates the structure in which the second base 120 and the heat insulation layer 130 are in contact with each other, other layers may be disposed between the second base 120 and the heat insulation layer 130. In this case, the pattern may be formed in the other layer, and the pattern may not be formed. Similarly, in FIG. 2, the structure in which the heat insulating layer 130 and the first insulating layer 150 are in contact with each other is illustrated, but another layer may be disposed between the heat insulating layer 130 and the first insulating layer 150. .

[Material of each component of heater unit 10]
As the first substrate 110 and the second substrate 120, a metal substrate or a semiconductor substrate can be used. As the metal substrate, an aluminum (Al) substrate, a titanium (Ti) substrate, or the like can be used. As the semiconductor substrate, a silicon (Si) substrate, a silicon carbide (SiC) substrate, a gallium nitride (GaN) substrate, or the like can be used. Here, the thermal conductivity of the substrate is about 236 W / mK for Al, about 21.9 W / mK for Ti, about 168 W / mK for Si, about 100 W / mK for SiC, and about 168 W / mK for GaN. is there. The first base material 110 and the second base material 120 may be the same material or different materials. The thermal conductivity of the first base material 110 and the second base material 120 is preferably 100 W / mK or more. In the present embodiment, Al is used as the first base material 110 and the second base material 120.

  The heat insulating layer 130 may have a thermal conductivity lower than at least the second base material 120. Further, the heat insulating layer 130 may have a lower thermal conductivity than the first base material 110. The heat insulating layer 130 may have a lower thermal conductivity than at least the first insulating layer 150. Further, the heat insulating layer 130 may have a lower thermal conductivity than the second insulating layer 160. The thermal conductivity of the heat insulating layer 130 is designed so that the temperature of the upper surface (the surface of the second insulating layer 160) of the heater unit 10 reaches 100 ° C. For example, the heat conductivity of the heat insulation layer 130 can be 21 W / mK or less.

As the heat insulating layer 130, SUS, silicon oxide (SiO ₂ ), silicon nitride (SiN), or the like can be used. The heat insulation layer 130 should just be a material whose heat conductivity is lower than the 2nd base material 120, and can be suitably selected according to the heat conductivity of the material used for the 2nd base material 120. Here, the thermal conductivity of the above materials is about 16.7 W / mK for SUS, about 1.4 W / mK for SiO ₂ , and about 20.0 W / mK for SiN. Moreover, the heat insulation layer 130 should just be a material whose heat conductivity is lower than the 1st insulating layer 150, and can be suitably selected according to the heat conductivity of the material used for the 1st insulating layer 150. In the present embodiment, SUS is used as the heat insulating layer 130.

  When SUS is used as the heat insulating layer 130, the thickness of the SUS can be 1 mm or more and 10 mm or less. Moreover, in order to implement | achieve the heat insulation layer 130 with low heat conductivity, the heat insulation layer 130 may have a pore. In other words, the heat insulating layer 130 may be a porous material. When a porous material is used as the heat insulating layer 130, the heat insulating layer 130 having a pore content of 1% to 20% can be used. Preferably, the pore content of the heat insulating layer 130 is 10% or more and 20% or less. Here, for example, when porous SUS is used as the heat insulating layer 130, the thermal conductivity of SUS becomes smaller than the above value (SUS bulk characteristic value). Specifically, the thermal conductivity of porous SUS is 2 W / mK or more and 17 W / mK or less. In addition, said heat conductivity is a value in the case of 25 degreeC measured by the laser flash method.

  The heat insulating layer 130 is required to have adhesiveness in addition to the above thermal conductivity. Specifically, the adhesiveness that does not peel is required in a cycle test in which room temperature and 150 ° C. are alternately repeated. Further, the heat insulating layer 130 is required to have resistance to the process of forming the heating element 140, the first insulating layer 150, and the second insulating layer 160.

  Porous SUS can be formed by, for example, a cold spray method. The cold spray method is a method of forming a film by colliding with a base material in a solid state in supersonic flow with an inert gas without melting or gasifying the material. In this embodiment, in order to adjust the thickness of SUS, after forming SUS by the cold spray method, it was thinned to a desired thickness by grinding. By forming SUS by a cold spray method, a porous SUS layer as described above can be realized. By adjusting the formation conditions of the cold spray method, the content of pores in the porous SUS layer can be adjusted. SUS may be formed by a method other than the cold spray method.

  If the difference between the thermal expansion coefficient of SUS and the thermal expansion coefficient of the second base material 120 is large, it is difficult to form SUS on the second base material 120, but this difficulty is caused by forming by the cold spray method. Can be resolved. Further, SUS formed by the cold spray method has high adhesion strength, and for example, adhesion strength higher than that of an aluminum substrate can be obtained. Further, SUS can be easily thickened by a cold spray method.

  In the above, SUS was formed using a cold spray method in order to form a porous SUS. However, in addition to the cold spray method, plasma spraying, flame spraying, arc spraying, high-speed flame spraying (HVOF: High Velocity Oxygen Fuel, Alternatively, it can be formed by a method such as HVAF: High Velocity Air Fuel) or warm spray. On the other hand, when forming SUS having no pores or having a pore content of 1% or less, methods such as sputtering, brazing, and diffusion bonding can be used.

  As the heating element 140, a conductor that generates Joule heat by an electric current can be used. As the heating element 140, a refractory metal such as tungsten (W), tantalum (Ta), molybdenum (Mo), or platinum (Pt) can be used. However, in addition to the above refractory metals, the heating element 140 may be an alloy containing iron (Fe), chromium (Cr), and Al, an alloy containing nickel (Ni) and Cr, SiC, molybdenum silicide, and carbon. A non-metallic body such as (C) can be used. In the present embodiment, W is used as the heating element 140.

The 1st insulating layer 150 and the 2nd insulating layer 160 are arrange | positioned in order to suppress that the heat generating body 140 is electrically connected with another member. That is, a material that sufficiently insulates the heating element 140 from other members can be used. As the first insulating layer 150 and the second insulating layer 160, Al ₂ O ₃ , aluminum nitride (AlN), SiO ₂ , SiN, or the like can be used. Here, the thermal conductivity of Al ₂ O ₃ is about 30.0 W / mK, and the thermal conductivity of AlN is about 285 W / mK. The first insulating layer 150 and the second insulating layer 160 may be made of the same material or different materials. In the present embodiment, Al ₂ O ₃ is used as the first insulating layer 150 and the second insulating layer 160.

  As described above, according to the heater unit 10 of the first embodiment, the heat insulating layer 130 having a lower thermal conductivity than the second base material 120 is disposed between the heating element 140 and the second base material 120. Therefore, when heating by the heating element 140 is performed while flowing the cooling water through the first flow path 115, it is possible to prevent a part of the heat generated in the heating element 140 from being taken away by the cooling water. As a result, it is possible to prevent the in-plane uniformity of the heating temperature of the heater unit 10 from being affected by the position of the first flow path 115. In addition, the ultimate temperature due to heating of the heater unit 10 can be made higher than in the prior art.

  In addition, by using SUS for the heat insulating layer 130, the heat insulating layer 130 having a low thermal conductivity can be realized at a low cost by a simple method. Moreover, the heat insulation of the heat insulation layer 130 can be improved more because the thickness of SUS shall be 1 mm or more and 10 mm or less. Further, since the heat insulating layer 130 has pores of 1% or more and 20% or less, it is possible to realize a thermal conductivity that is lower than the original heat conductivity of the material used for the heat insulating layer 130.

  In addition, since the thermal conductivity of the heat insulating layer 130 is lower than the thermal conductivity of the first insulating layer 150, it is possible to further suppress the removal of a part of the heat generated in the heating element 140 by the cooling water. Moreover, the thermal conductivity of the 2nd base material 120 is 100 W / mK or more, and it can make the in-plane uniformity and ultimate temperature of the heating temperature of the heater unit 10, and a cooling function compatible.

Second Embodiment
The overall configuration of the heater unit according to the second embodiment of the present invention will be described with reference to FIG. The heater unit according to the second embodiment of the present invention has a heating mechanism and a cooling mechanism as in the first embodiment. The heater unit according to the second embodiment can be used for a CVD apparatus, a sputtering apparatus, a vapor deposition apparatus, an etching apparatus, a plasma processing apparatus, a measurement apparatus, an inspection apparatus, a microscope, and the like. However, the heater unit according to the first embodiment is not limited to the one used in the above apparatus, and can be used for an apparatus that needs to heat or cool the substrate.

[Configuration of Heater Unit 20]
Since the top view of the heater unit 20 of the second embodiment is the same as that of the heater unit 10 of the first embodiment, the description thereof is omitted here. Further, since the sectional view of the heater unit 20 is similar to the sectional view of the heater unit 10, in the description of the heater unit 20, the description of the same structure as the heater unit 10 will be omitted, and the difference will be mainly described. .

  FIG. 3 is a cross-sectional view of a heater unit according to an embodiment of the present invention. As shown in FIG. 3, the heater unit 20 is different from the heater unit 10 in that it includes a third base material 410, a fourth base material 420, and a thermal diffusion layer 430.

  The third base material 410 and the fourth base material 420 are disposed between the second base material 120 and the heat insulating layer 130, and a cooling gas or a process gas is interposed between the third base material 410 and the fourth base material 420. A second flow path 415 serving as a flow path is provided. In FIG. 3, the 2nd flow path 415 is formed by joining the 3rd base material 410 with which the upper surface is flat, and the 4th base material 420 with which the lower surface was provided with the recessed part. The thermal diffusion layer 430 is disposed above the second insulating layer 160. Here, although not shown, a part of the second flow path 415 is provided in the shaft 200 via a connection hole provided in the third base material 410, the second base material 120, and the first base material 110. Connected to the gas pipe.

  Although FIG. 3 illustrates the structure in which the second flow path 415 is formed by the flat upper surface of the third base material 410 and the recesses on the lower surface of the fourth base material 420, the structure is not limited to this. For example, a recess may be provided on the upper surface of the third base material 410, and the lower surface of the fourth base material 420 may be flat. Or the recessed part may be provided in both the upper surface of the 3rd base material 410, and the lower surface of the 4th base material 420. FIG. Alternatively, the second flow path 415 may be provided inside the fourth base material 420. When the flow path is provided inside the fourth base material 420, the third base material 410 can be omitted.

[Material of each component of heater unit 20]
As the third base material 410 and the fourth base material 420, a metal base material or a semiconductor base material can be used. As the metal substrate, an Al substrate, a Ti substrate, or the like can be used. As the semiconductor substrate, a Si substrate, a SiC substrate, a GaN substrate, or the like can be used. The third base material 410 and the fourth base material 420 may be the same material or different materials. The third base material 410 and the fourth base material 420 may be the same material as the first base material 110 and the second base material 120 or may be different materials. In the present embodiment, Al base materials are used as the third base material 410 and the fourth base material 420.

  The thermal diffusion layer 430 may have a higher thermal conductivity than at least the second insulating layer 160. Further, the thermal diffusion layer 430 may have a higher thermal conductivity than the first insulating layer 150. As the thermal diffusion layer 430, a material having high thermal conductivity such as Al, copper (Cu), silver (Ag), or gold (Au) can be used.

  As described above, according to the heater unit 10 of the first embodiment, the heat diffusion layer 430 is provided above the heating element 140, so that the heat generated by the heating element 140 is in the surface direction of the heat diffusion layer 430. Diffused. As a result, the in-plane uniformity of the heating temperature of the heater unit 20 is improved. Moreover, the ultimate temperature by heating of the heater unit 20 can be made higher than before.

  Further, since the second flow path 415 is provided between the first flow path 115 and the heat insulating layer 130, for example, when the heater unit 20 is heated, a heating gas is allowed to flow through the second flow path 415, thereby A portion of the heat generated in the heating element 140 can be prevented from being taken away by the cooling water flowing in the one flow path 115, and the same effect (improving in-plane uniformity and increasing the ultimate temperature) can be achieved. Can be obtained. On the other hand, when the heater unit 20 is cooled, the cooling efficiency can be improved by flowing the cooling gas through the second flow path 415.

  Hereinafter, Example 1 of the present invention will be specifically described with reference to FIGS. 4 and 5. In Example 1, the result of investigating the relationship between the thickness of the heat insulating layer 130 or the ultimate temperature of the heater unit surface with respect to the thermal conductivity will be described. However, the present invention is not limited to the first embodiment. FIG. 4 is a diagram showing the relationship between the thickness of the heat insulating layer and the temperature reached on the stage surface in the heater unit according to one embodiment of the present invention. FIG. 5 is a diagram showing the relationship between the thermal conductivity of the heat insulating layer and the ultimate temperature of the stage surface in the heater unit according to one embodiment of the present invention.

The results shown in FIGS. 4 and 5 are simulation results obtained by calculation. The analysis model used for the calculation will be described below. The analysis model structure is designed assuming the structure shown in FIG. 2, and is a structure in which a cooling channel, an Al layer, a heat insulating layer, a heating element, and an Al ₂ O ₃ layer are stacked in order from the bottom. Here, the above structure is referred to as a heater unit.

In the above structure, the interface of each layer is completely bonded. The uppermost Al ₂ O ₃ layer was in contact with the atmosphere set at 20 ° C., and the surface emissivity was set to 0.5. W (characteristic value: 20 ° C.) was adopted as the heating element, and the heat flow rate was fixed at 900 mW / mm ² . The boundary condition between the cooling flow path and the Al layer was set to 20 ° C. Incidentally, Al layer, for the Al ₂ O ₃ layer, was adopted bulk property value. Using the above analysis model, the temperature reached on the surface of the Al ₂ O ₃ layer was obtained by calculation.

  In the simulation model of the simulation result shown in FIG. 4, the thermal conductivity of the heat insulation layer was fixed at 17 W / mK, and the thickness of the heat insulation layer was changed. In the analysis model of the simulation result shown in FIG. 5, the heat conductivity of the heat insulating layer was changed by fixing the thickness of the heat insulating layer to 1 mm.

  As shown in FIG. 4, it was confirmed that the ultimate temperature of the heater unit tends to become high as the thickness of the heat insulating layer increases. It is confirmed that the change of the reached temperature with respect to the thickness of the heat insulating layer is a linear change. As shown in FIG. 5, it was confirmed that the temperature reached by the heater unit tended to become low as the thermal conductivity of the heat insulating layer increased. It is confirmed that the change of the ultimate temperature with respect to the thermal conductivity of the heat insulating layer is an exponential change.

  Here, the ultimate temperature required for the heater unit is required to be 100 ° C. or higher in order to evaporate water adhering to the surface of the substrate. In such a case, the result of FIG. 4 shows that the thickness of the heat insulation layer needs to be at least 1.57 mm or more (when the heat conductivity of the heat insulation layer is 17 W / mK). Moreover, it turns out from the result of FIG. 5 that the heat conductivity of a heat insulation layer needs to be at least 25 W / mK or less (when the thickness of a heat insulation layer is 1 mm).

  As described above, according to Example 1, for example, in order to make the ultimate temperature of the heater unit 100 ° C. or higher, a thickness of 1.57 mm or more is necessary when the thermal conductivity of the heat insulating layer is 17 W / mK. It turned out to be. Moreover, in order to achieve said ultimate temperature, when the thickness of the heat insulation layer was 1 mm, it became clear that it was necessary to make heat conductivity 25 W / mK or less.

  Hereinafter, Example 2 of the present invention will be specifically described with reference to FIG. In Example 2, the result of observing the structure of porous SUS formed by a cold spray method as a heat insulating layer will be described. FIG. 6 is a diagram showing an electron microscope image of the heat insulating layer in the heater unit according to one embodiment of the present invention. FIG. 6 shows electron microscope images of three types of SUS formed by the cold spray method under different conditions.

  In the electron microscope image shown in FIG. 6, a bright place (bright part 610) is SUS, and a dark place (dark part 620) is a pore. As shown in FIG. 6, it was confirmed that pores having a size of several tens of μm to several hundreds of μm were formed in SUS formed by the cold spray method. Here, the abundance ratio of the pores with respect to the electron microscope image of FIG. 6 is about 16.3% for SUS of (a), about 11.8% for SUS of (b), and about 12.6 for SUS of (c). %. As a result of evaluation by SUS formed by changing the conditions of the cold spray method, it has been confirmed that a good heat insulating effect can be obtained when the pore content in the heat insulating layer is 1% or more and 20% or less. In particular, when the heat insulating layer contains pores of 10% or more and 20% or less, a further better heat insulating effect can be obtained.

  As described above, according to Example 2, it has been found that SUS has pores, so that it is possible to obtain a lower thermal conductivity than the bulk properties of SUS. In addition, since SUS has pores, the interface stress between the second base material 120 and the heat insulating layer 130 or the interface stress between the heat insulating layer 130 and the first insulating layer 150 can be relieved. it can.

  Note that the present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit of the present invention.

10, 20: heater unit 100: plate portion 110: first base material 111: source 113: drain 115: first flow path 115-1, 115-2: folded portion 117: source connection hole 119: drain connection hole 120: 2nd base material 130: heat insulation layer 140: heating element 150: 1st insulating layer 160: 2nd insulating layer 200: shaft part 211: source pipe 213: drain pipe 310: base material 320: heater part 410: 3rd base material 415: 2nd flow path 420: 4th base material 430: Thermal diffusion layer

Claims (9)

A substrate having a cooling channel;
A heater part disposed above the substrate and having a heating element;
A heat insulating layer disposed between the substrate and the heater portion;
A heater unit comprising:   The heater unit according to claim 1, wherein the heat conductivity of the heat insulation layer is lower than the heat conductivity of the base material.   The heater unit according to claim 2, wherein the heat insulating layer is SUS.   The heater unit according to claim 3, wherein the thickness of the SUS is 1 mm or more and 10 mm or less. The thermal insulation layer has pores;
2. The heater unit according to claim 1, wherein a content ratio of the pores in the heat insulating layer is 1% or more and 20% or less. Further comprising an insulator covering the heating element;
The heater unit according to claim 1, wherein the heat conductivity of the heat insulation layer is lower than the heat conductivity of the insulator. The thermal conductivity further has a thermal diffusion layer above the heater part,
The heating element has a conductor and an insulator covering the conductor,
2. The heater unit according to claim 1, wherein a thermal conductivity of the thermal diffusion layer is higher than a thermal conductivity of the insulator.   The heater unit according to claim 1, wherein the base material has a thermal conductivity of 100 W / mK or more.   The heater unit according to claim 1, wherein the substrate has a gas flow path.