JP3864088B2 - Electronic heating hot plate device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an electronic heating hot plate.
[0002]
[Prior art]
A conventional hot plate is shown in FIG. The heater wire 20 is energized, and the sample holder 21 is heated by heat conduction from the heater wire. The sample 22 to be heated is heated by heat conduction from the sample holder. In the heating method using this heater wire, the heater wire has the highest temperature, the next is the sample holder, and the lowest temperature is the sample to be heated. For example, when it is desired to heat the sample to be heated to 600 ° C., the heater wire temperature may have to be 1000 ° C. The heater wire must be made of a durable material with high heat resistance. Since the heater wire is made strong, the heat capacity of the entire hot plate 23 is increased. In order to raise the temperature of the hot plate having a large heat capacity, it is necessary to supply a large electric power to the heater wire. Rapid heat and rapid cooling is difficult due to large power consumption and large heat capacity. Since the heater wires can be arranged only sparsely, a contrivance is made such as arranging the reflector 24 in order to improve the thermal uniformity of the sample holder. However, the temperature of the sample holder in the portion where the heater wire is close and the portion where the heater wire is far from the heater wire. It is difficult to eliminate the difference. If this temperature difference is to be reduced, the heat capacity of the hot plate tends to increase further, so that the problem of difficulty in power consumption and rapid heating / cooling becomes obvious.
A lamp heating method has been developed as a heating method for reducing the above-mentioned problems of the heater wire type hot plate. A block diagram of a lamp heating type hot plate is shown in FIG. A halogen lamp 25 is placed above the sample to be heated placed on the sample holder 21 and is lit, and the sample to be heated is heated by radiation from the lamp. Since the structure of the sample holder is simple, it has the advantage of light heat capacity and rapid quenching / cooling. In particular, when heating by lamp irradiation while forcibly keeping the sample holder at a low temperature by water cooling or the like, the sample to be heated can be rapidly cooled by heat conduction from the cooled sample holder after the lamp is turned off.
[0003]
[Problems to be solved by the invention]
However, the lamp heating method also has a problem that the lamp itself has a higher temperature than the sample to be heated. Since the lamp emits light in addition to the heat rays, only a part of the power consumed by the lamp contributes to the heating of the heated sample. For this reason, large electric power consumption will be made for temperature rising of a sample to be heated. When the sample holder is cooled, a part of the heat amount of the heat rays from the lamp is consumed by the sample holder, so that the power consumption for heating becomes relatively large. As described above, the conventional heating method has a problem that the temperature rising / falling rate is slow like the heater heating method, and the power consumption required for heating is large like the lamp heating method. It was not possible to satisfy the characteristics of both heating and cooling rate and heating power consumption.
[0004]
[Means for Solving the Problems]
The electronic heating hot plate apparatus according to the present invention is characterized in that, in addition to the feature of the conductive hot plate 1 and the cathode substrate 4 in contact with the sample to be heated, carbon nanotubes are coated on the surface of the cathode substrate. With one feature,
Second, in addition to the first feature, the cathode substrate is fixed, and the hot plate rotates.
Thirdly, in an electronic heating hot plate apparatus composed of an insulating hot plate 1 in contact with a sample to be heated and a cathode substrate 4, the insulating hot plate is partially open so that the conductive surface of the sample to be heated is electrically conductive. Is exposed in the cathode substrate direction, and the surface of the cathode substrate is coated with carbon nanotubes,
Fourth, in addition to any one of the first to third features, the center portion of the cathode substrate is not coated with the carbon nanotube. Fifth, either the first or the second In addition to the features, the hot plate has a structure in which an insulating base material and a conductive coating layer are formed on the back surface of the base material.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
In the electronic heating hot plate apparatus according to the present invention, in addition to the characteristic of the conductive hot plate 1 and the cathode substrate 4 that are in contact with the sample to be heated, the first surface of the cathode substrate is coated with carbon nanotubes. In the case of having the feature, a carbon nanotube having a sharp structure that has an effect of lowering the emission threshold electric field is applied to the cathode substrate as an electron field emission material. Some crystals of the coated carbon nanotubes are oriented upright in the direction of the hot plate. The cathode substrate and the hot plate are arranged substantially in parallel and opposed to each other, and the cathode substrate is set to a negative potential with respect to the hot plate, so that electrons are emitted from the end of the sharp structure of the carbon nanotube, and the emitted electrons are caused by the negative potential. Irradiate the hot plate with acceleration by an electric field. The irradiated hot plate is heated by the energy of electrons. The hot plate is heated by being irradiated with accelerated electrons, but the cathode substrate that emits electrons only emits electrons and is not heated. Note that the phenomenon of hot electrons being extracted is cooled. The cathode substrate is heated by Joule heat generated when extracted electrons are conducted through the cathode substrate or through the carbon nanotube, or by heat radiation from the adjacent hot plate. The temperature is slightly lowered or raised depending on the magnitude relationship between the cooling and temperature raising actions.
Second, in addition to the first feature, when the cathode substrate is fixed and the hot plate has a feature of rotating, the cathode substrate as an electron emission source and the hot plate (anode electrode) are in contact with each other. Since they do not need to be moved, they can be moved independently of each other. The hot plate can also be rotated. In this case, it is necessary to contact the electrode with the hot plate in order to determine the potential of the hot plate.
Thirdly, in an electronic heating hot plate apparatus composed of an insulating hot plate 1 in contact with a sample to be heated and a cathode substrate 4, the insulating hot plate is partially open so that the conductive surface of the sample to be heated is electrically conductive. Is exposed in the direction of the cathode substrate, and has a feature in which carbon nanotubes are coated on the surface of the cathode substrate, it utilizes the property that electrons are collected on a conductive electrode (anode electrode). By making a part of the sample to be heated conductive and making other parts of the sample and the hot plate insulative, electrons are concentrated only on the conductive part and only that part is heated intensively.
Fourth, in addition to any of the first to third features, when the central portion of the cathode substrate has a feature in which the carbon nanotube is not applied, it corresponds to the central portion where the temperature is most likely to rise. By not arranging the electron source in the central part of the cathode substrate, electron heating does not act on the central part.
Fifth, in addition to either the first or the second feature, when the hot plate has a feature in which an insulating base material and a conductive coating layer are formed on the back surface of the base material. The hot plate surface on which the sample to be heated is mounted is insulative, and the back surface is formed with a conductive coating layer. This structure shares the function of accelerating and receiving electrons emitted from the cathode substrate in the coating layer, and the function of heating only without leaking electrons to the heated sample in the insulating base material.
[0006]
【Example】
A first embodiment of the present invention will be described with reference to FIG. FIG. 1 depicts a hot plate 1 for heat-treating a semiconductor substrate in a vacuum apparatus. A silicon wafer 100 having a diameter of 300 mm is fixed on the heating stage 2. This heating stage has a substantially cylindrical shape with an outer diameter of 340 mm and a height of 2 mm. It consists of a curved side and a disk-shaped top plate. It was formed of a molybdenum material having a thickness of 0.3 mm. The lower end of the side surface is hermetically connected to an insulating spacer 2 made of an alumina insulator. The height of the insulating spacer is 5 mm. The lower end of this insulating spacer is made of stainless steel having an outer diameter of 340 mm and a thickness of 2 mm, and is connected to a disk-like bottom plate 3. A cathode substrate 4 is fixed on the bottom plate 3. The cathode substrate is a stainless disk and has a thickness of 4 mm. Carbon nanotubes are applied on the entire top surface by screen printing. In the carbon nanotube, tubes having a diameter in the range of several nanometers to several tens of nanometers are erected in a substantially vertical direction at intervals of about 50 microns. The container shown in the figure is a vacuum container. The getter 7 is built in and the degree of vacuum is maintained on the order of 10 ^ -5 Pa. A negative high voltage is applied to the cathode electrode to generate an electric field with the hot plate 1 having a ground (zero) potential. The electrons 10 emitted from the cathode substrate are accelerated along the equipotential surface and irradiated on the hot plate. The irradiated hot plate is heated by the energy of electrons. In this embodiment, the distance between the facing cathode substrate and the hot plate is about 3 mm. When a potential of −3 kV is applied to the cathode substrate, electrons start to be emitted, and when a potential of −10 kV is applied, 100 mA / cm 2 electrons are emitted. The electrons supply 1 kW of power per square centimeter to the hot plate, which heats the hot plate.
[0007]
A second embodiment of the present invention will be described. FIG. 2 shows a configuration diagram thereof. It is an example of the hot plate incorporated in the vacuum vessel. A copper cathode substrate 4 is placed on a bottom plate 3 fixed inside the vacuum vessel. CNTs are oriented and grown in advance on the surface of the cathode substrate by CVD. A rotary hot plate 1 is disposed above the cathode substrate. A 12-inch size silicon substrate is mounted on the hot plate as the sample 100 to be heated. A spring electrode 5 is in contact with the side surface of the substantially cylindrical hot plate 1. The cathode substrate is at ground (zero) potential, and a positive potential is applied to the hot plate 1 via the spring electrode 5. 5 kV is applied to the spring electrode. The facing gap between the hot plate and the cathode electrode is adjusted to 2 mm. In this embodiment, the vicinity of the cathode electrode is in the atmospheric state when the vacuum vessel is in the atmospheric state, and in the vacuum state in the vacuum state. This is an example of a hot plate that does not have a special vacuum function.
[0008]
A third embodiment of the present invention will be described. The hot plate is characterized by having an insulating sample holder 9. FIG. 3 shows a configuration diagram. This is an example of an apparatus for joining small conductive protrusions 8 to a silicon substrate (heated sample 100) provided with a circuit that functions as a mother board. In FIG. 2, through-holes are provided at various locations on the insulating hot plate. The electrons 10 that have jumped out of the cathode are collected on the conductive protrusions. As a result, the conductive protrusion is intensively heated. This is applied to the case where conductive protrusions are fused at specific locations on a silicon substrate. As an example similar to this example, there is an example in which a conductive pattern is laid out on the heated sample itself with a large opening near the center of the insulating sample holder. In this hot plate, electrons accelerated in a concentrated manner can be collected and heated locally only in a conductive pattern portion connected to an external electrode and applied with a positive high voltage. If the conductive pattern is finely processed, local overheating according to the fine processing is possible.
[0008]
Example 4 of the present invention is depicted in FIG. The CNT coating pattern on the cathode substrate 4 is drawn. CNTs were concentrically triple coated on a conductive cathode substrate by screen printing. In order to uniformly heat a hot plate (not shown) to be heated, the electron density in the central portion of the cathode substrate is lowered (no CNT is applied to the center) and CN is applied, and CNT is applied. The three circular patterns are not in contact with each other.
[0009]
Example 5 of the present invention is depicted in FIG. In this example, the sample 100 to be heated is mounted on the surface of the completely insulating sample holder 26, and the metal coating layer 27 is formed on the back surface of the holder. A cathode substrate 4 is arranged at a distance of 5 mm at a position facing the metal coating layer, and carbon nanotubes are applied as an emitter material on the cathode substrate surface. The completely insulating holder means that the heated sample mounted thereon and the coating layer are completely insulated. As the substrate, an insulator having heat resistance such as SiO2 (quartz) or Al2O3 (alumina) is used. A plating layer such as nickel may be used as the metal coating layer, or a conductive layer may be applied by mixing graphite powder into a glass paste. A conductive material is used for the cathode substrate. Copper or stainless steel may be used. Electrons emitted from the cathode substrate are accelerated by a voltage applied between the cathode substrate and the coating layer, enter the coating layer, and the energy of the completely insulating holder is increased by the energy.
[0010]
【The invention's effect】
When the electronic heating hot plate apparatus of the present invention is used, heating satisfying all the conditions of uniform heating, rapid temperature increase / decrease, and heating with low power consumption can be performed. Even when the sample to be heated is heated while being rotated, it can be realized with a simple and low-cost structure.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a hot plate of Example 1. FIG. 2 is a configuration diagram of a hot plate of Example 2. FIG. 3 is a configuration diagram of a hot plate of Example 3. FIG. Fig. 5 shows the configuration of the hot plate of Example 5. Fig. 6 shows the configuration of the conventional heater wire type hot plate. Fig. 7 shows the configuration of the conventional lamp heating type hot plate. Configuration diagram [reference] 1 is a hot plate, 2 is a spacer, 3 is a bottom plate, 4 is a cathode substrate, 5 is a spring electrode, 6 is a CNT coating pattern, 7 is a getter, 8 is a conductive protrusion, 9 is an insulating sample holder 10 is an electron, 11 is an equipotential surface, 20 is a heater wire, 21 is a sample holder, 22 is a sample to be heated, 23 is a hot plate, 24 is a reflector, 25 is a halogen lamp, and 26 is a fully insulating sun. Holder was installed, 27 metal coating layer 100 is heated sample.

Claims (5)

An electronic heating hot plate apparatus comprising a conductive hot plate 1 in contact with a sample to be heated and a cathode substrate 4, wherein carbon nanotubes are coated on the surface of the cathode substrate. 2. The electronic heating hot plate apparatus according to claim 1, wherein the cathode substrate is fixed and the hot plate rotates. In an electronic heating hot plate apparatus composed of an insulating hot plate 1 and a cathode substrate 4 in contact with a sample to be heated, the insulating hot plate is partially opened, and the conductive surface of the sample to be heated is the cathode substrate. An electronic heating hot plate apparatus characterized by being exposed in a direction and having carbon nanotubes coated on the surface of the cathode substrate. 4. The electronic heating hot plate apparatus according to claim 1, wherein the carbon nanotube is not applied to a central portion of the cathode substrate. 3. The electronic heating hot plate apparatus according to claim 1, wherein the hot plate has a structure in which an insulating base material and a conductive coating layer are formed on the back surface of the base material. Plate equipment.

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