JPH10321355A - Planar heating unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a planar heating unit capable of instantaneously transmitting heat generated in a heating resistor to a heating base material, heating the heating base material to the specified temperature in a short time to quicken a temperature rising speed, quickly changing a setting temperature, and uniformly heating substances to be heated. SOLUTION: The heating unit is formed by stacking three members of a heat transmitting base material 3 in which an insulating film 22 formed by curing resin containing at least alumina as inorganic powder is formed on its one surface and a heating resistor 4 is sintered on the insulating film 22, a substrate 1 in which the surface at least facing the heating resistor 4 has insulating capability, and a heating base material 5 arranged on the other surface, where the heating resistor 4 is not formed, of the heat transmitting base material 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar heating device used for heating, for example, a semiconductor wafer or a liquid crystal substrate.

[0002]

2. Description of the Related Art Normally, in a process of manufacturing a semiconductor wafer or a liquid crystal substrate, a pattern is printed on the wafer or the liquid crystal substrate, a cleaning process is performed, and then the wafer or the liquid crystal substrate is heated to a predetermined temperature and the process proceeds to the next step. It has become. The conventional heating device used at this time is called a planar heating device because a plate-like object such as a wafer or a liquid crystal substrate is placed on a heating plate of the heating device and heated from the back surface. is there.

A conventional planar heating device will be described with reference to FIG. A mica heater 7 is formed on the upper surface of a base 6 made of aluminum, and an aluminum heating substrate 8 serving as a heating plate is formed on the upper surface so as to sandwich the mica heater 7.
Is arranged. Then, non-heated objects such as wafers and liquid crystal substrates are placed one by one on the heating base material 8 and heated to a predetermined temperature by the heat generated from the mica heater 7.

[0004] The mica heater will be described in detail with reference to FIG. In the mica heater, a concave portion is formed on one surface of the mica plate 71 by etching, and the SU
A heating resistor h made of a thin metal foil made of S is arranged, and another mica plate 72 of the same material is arranged above the heating resistor h so as to sandwich the heating resistor h. Then, the heat generated from the heating resistor h is transmitted to the upper mica plate 72, and this heat is further transmitted to the upper heating base material 8 to heat the non-heated material.

On the other hand, as shown in FIG. 7, instead of a mica heater, a conductive heat-generating paste is directly applied to the surface of the heating plate opposite to the side on which the non-processed material is placed as the heat source of the planar heating device. There is a type in which a heating resistor is formed by firing and this heating resistor is used as a heat source. Such a technique is disclosed in Japanese Unexamined Patent Application Publication No.
No. 27245.

[0006]

However, the conventional planar heating apparatus using a mica heater as a heat source has the following problems. Plates 71 and 72 covering heating resistor h
Since high insulation properties are required, mica is used. However, mica has a very low thermal conductivity.
Since it is about 55 to 0.79 [k × (W · m ⁻¹ · K ⁻¹ ) ⁻¹ ], even if a current flows through the heating resistor h, the temperature of the mica heater 7 does not immediately rise, and Then the heating resistor h
Is not transmitted to the heating base material 8.

When a plurality of non-heated materials are successively heated, a large amount of heat is taken away from the heating substrate 8. Therefore, the heating substrate 8 is increased in thickness to increase the heat capacity, thereby increasing the amount of heat. , The temperature of the heating base material 8 does not drop extremely. In such a structure, the heating rate of the mica heater 7 is low, and the heat capacity of the heating base 8 is large. Did not reach. Specifically, in a planar heating device in which the surface area of the heating base 8 is 450 cm ² and the heating resistor h is 2.5 (W / cm ² ), the temperature of the heating base 8 rises from 30 ° C. to 150 ° C. It took about 30 minutes to do.

[0008] Non-heated objects such as wafers and liquid crystal substrates are:
Heating is performed at various set temperatures in the heating step. In such a planar heating device, the temperature rising speed of the mica heater 7 is slow, and the heat capacity of the heating base material 8 is large. When trying to set a high temperature, the temperature of the heating base material 8 could not be quickly raised. Conversely, if it is attempted to set the temperature from a certain temperature to a low temperature, the heat capacity of the heating base 8 is large, so that it takes time to radiate the heat from the heating base 8. I couldn't lower it. In other words, the conventional planar heating device using the mica heater as a heat source cannot quickly respond to a heating step having a different set temperature.

Further, as described above, the mica plate 71,
No. 72 has a very low thermal conductivity and a large heat capacity of the heating base material 8, so that it is not easy to make the temperature of the surface of the heating base material 8 on which the non-heated material is placed uniform.

Further, in the case of a conventional planar heating device in which a heating resistor is formed by firing the conductive heating paste of FIG. 7 and this is used as a heat source, there are the following problems. The conductive heat-generating paste is fired at a high temperature of about 450 ° C. to become a heat-generating resistor. In this firing step, the heating plate becomes hot and distorted, and the surface on which the non-heated object is placed is curved, and the non-heated object is curved. When the heated object is placed on the heating plate, a portion where the non-heated object comes into contact with the portion that contacts the heating plate is formed, and as a result, the non-heated object cannot be heated to a uniform temperature. There was a problem.

The present invention has been made in view of the above circumstances, and an object of the present invention is to instantaneously transmit heat generated by a heating resistor to a heating plate, and to heat the heating plate to a predetermined temperature in a short time. The present invention is to provide a planar heating device which can speed up the temperature rising speed by reaching the temperature, and can quickly change the set temperature, and can uniformly heat the non-heated material.

[0012]

According to a first aspect of the present invention, there is provided a planar heating apparatus comprising: an insulating film formed by curing a resin containing at least alumina as an inorganic powder on one surface; The heat transfer base is formed, and a heating resistor is fired on the insulating film, a base having at least a surface facing the heating resistor having an insulating property, and the heating resistor of the heat transfer base are formed. It is characterized in that a heating base material arranged on the other surface, which is not formed, and three members made of the same are overlapped and fixed.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of the planar heating device of the present invention, and FIG. 2 is a cross-sectional view taken along the line XX in FIG. In the planar heating device of the present invention, an insulating film 22 formed by curing a resin containing at least alumina as an inorganic powder is formed on one surface, and a heat transfer element in which the heating resistor 4 is fired on the insulating film 22 is formed. A base member 3 having an insulating film 21 formed on a surface facing the heating resistor 4; and a heating substrate disposed on the other surface of the heat transfer base member 3 where the heating resistor 4 is not formed. This is a structure in which a member 5 and three members made of the material 5 are overlapped and fixed. Then, a non-heated object such as a wafer or a liquid crystal substrate is placed on the surface of the heating base material 5 which is a heating plate.
It is to be heated.

The substrate 1 is a substrate of the planar heating device. In this embodiment, the substrate 1 is a SUS plate having a thickness of 1 mm.
An insulating film 21 is formed on one surface in contact with the heating resistor 4. The insulating film 21 may be any as long as it secures insulation between the heating resistor 4 and the base 1, and is specifically formed by curing an organopolysiloxane resin containing alumina as an inorganic powder having a thickness of 150 μm. It is a membrane. In the present embodiment, the base 1 is made of a metal SUS plate. However, at least the surface in contact with the heating resistor 4 may be an insulator, and even if the entire base 1 is an insulating ceramic plate. good.

The heat transfer substrate 3 has an insulating film 22 formed on one surface thereof, and a heat generating resistor 4 on the surface of the insulating film 22.
Are formed. The insulating film 22 secures insulation between the heating resistor 4 and the heat transfer base 3, and also forms the heating resistor 4.
The heat generated by the heat transfer to the heat transfer base material 3,
Specifically, the thermal conductivity is 21 [k × (W · m ⁻¹ · K ⁻¹ )
^[-1 ] is a film obtained by curing an organopolysiloxane resin containing alumina as an inorganic powder having a thickness of 150 μm.
That is, since the alumina dispersed in the insulating film 22 has a significantly higher thermal conductivity than mica, the heat generated in the heat generating resistor 4 is transmitted to the heat transfer base material 3 in a good manner. Further, the heat transfer base material 3 is a material that satisfactorily transmits the heat generated by the heat generating resistor 4 to the upper heating base material 5, and is specifically a SUS plate having a thickness of 0.5 mm.

On the insulating film 22 of the heat transfer base 3, a heating resistor 4 serving as a heat source is formed. Heating resistor 4
Is formed by baking a conductive heat-generating paste containing a silver-palladium alloy as a heat-resisting substance on the insulating film 22 and forming a spiral with an arbitrary width as shown in FIG. This heating resistor 4 has almost no change in resistance value with respect to temperature.
Predetermined heat generation starts immediately after the start of energization. Specifically, the calorific value per unit area (W / cm ² ) is 0.5 to 5.0, and in the present embodiment, the calorific value per unit area (W / cm ² ) is 2.2 to 5.0. It is a heating resistor.
Then, as shown in FIG. 3, the heating resistor 4a on the outer edge portion side
Are wider than the internal heating resistor 4b. This is because the amount of heat in this portion is increased in consideration of heat radiation from the outer edge of the planar heating device. As a method of increasing the amount of heat generated by the heat generating resistor 4a on the outer edge portion, a heat generating resistor having a different heat generation rate may be used in addition to increasing the width.

The heat-transfer substrate 3 is such that even if a heat-generating resistor 4 is formed by baking a conductive heat-generating paste on the heat-transfer substrate 3 at a high temperature of about 450.degree. It is preferable to use a SUS plate or a ceramic plate.

The heating substrate 5 as a heating plate has a high thermal conductivity and a high flatness on a surface on which an unheated object is placed. Specifically, the thermal conductivity is 236 [k × ( W ・ m ^-1・ K
^-1 ) ^-1 ] is an aluminum plate having a thickness of 2 mm.

Then, as shown in FIG. 4, the base 1 and the heat transfer base 3 are made of an insulating film 21 formed on the base 1 and the heat transfer base 3.
Are arranged so that the heating resistors 4 formed in
Further, the heating base material 5 is disposed above the heat transfer base material 3 and each is fixed with an adhesive or a screw or the like having a high thermal conductivity (not shown) to form a planar heating device.

According to the planar heating device of the present invention, since the insulating film 22 formed on the heat transfer base material 3 has alumina dispersed in the insulating film 22, it can be compared with the mica plate of the conventional mica heater. The heat conductivity is 40 times higher, and the heat generated by the heating resistor 4 is instantaneously transmitted to the heat transfer base 3, and the heat base 5 is directly connected to the heat transfer base 3 or by an adhesive having a high heat conductivity. Since it is fixedly arranged, the heat transmitted to the heat transfer base 3 is instantaneously transmitted to the heating base 5, and therefore, when the current flows through the heating resistor 4, the heat is immediately transmitted to the heating base 5. Can be.

Further, since the heat generated from the heating resistor 4 is instantaneously transmitted to the heating base 5 and can be heated, the temperature of the heating base 5 does not decrease even if a plurality of unheated objects are continuously heated. In addition, there is no need to use a heating base material having a large heat capacity as in the related art, and therefore, the heating base material 5 reaches a predetermined temperature in a short time, and the temperature rising speed can be increased.

Specifically, the surface area of the heating substrate 5 is 450
cm ² , the heating value per unit area of the heating resistor 4 (W /
cm ² ) is 2.2, the temperature of the heating base material rises from 30 ° C. to 150 ° C., but about 5 ° C.
The heating speed was reduced by 25 minutes as compared with the conventional planar heating device using a mica heater as a heat source.

Further, even when an unheated object such as a wafer or a liquid crystal substrate is heated at various set temperatures, as described above,
The heat generated from the heat generating resistor 4 is instantaneously transmitted to the heating base material 5 and the heating speed is fast, and the heat capacity of the heating base material 5 is small. 3 can be changed.

The heat transfer base 3 has a function of diffusing the heat generated by the heat generating resistor 4 and transmitting it to the upper heating base 5, so that the temperature of the heating base 5 can be made uniform. it can.

The heating resistor 4 is not formed directly on the heating base 5 which is a heating plate, but is formed on the heat transfer base 3 by firing. Since the sheet heating device is superposed, the heating base 5 is not distorted or curved at the time of firing, and further, under a high temperature condition in which the conductive heating paste is fired to form a heating resistor. Copper or brass, which could not be used in the past because of distortion and bending, can now be used as the heating base 5, and the heating base 5 has a high thermal conductivity and is generated by the heating resistor 4. The heat thus generated can be used more efficiently for heating non-heated materials.

[0026]

According to the planar heating device of the present invention, a heating resistor is formed on an insulating film obtained by curing a resin containing alumina as an inorganic powder formed on a heat transfer substrate. Therefore, the heat generated by the heat generating resistor is instantaneously transmitted to the heat transfer base, and the heat transmitted to the heat transfer base is instantly It is transmitted to. Furthermore, since it is not necessary to use a heating base material having a large heat capacity as in the past, the heating base material reaches a predetermined temperature in a short time,
The heating speed can be increased. Even when the non-heated member is heated at various set temperatures, the heat generated by the heating resistor is instantaneously transmitted to the heating base material, and the heat capacity of the heating base material is small, so that a predetermined temperature can be set to a desired value. The temperature of the heating substrate can be quickly changed to the temperature.

Further, the heat transfer base material has an effect of diffusing the heat generated by the heating resistor, and as a result, the temperature of the metal base material can be made uniform.

Further, since the heating resistor is not formed directly on the heating base, no distortion and bending occur in the heating base.
As the heating base material, a substance having a high thermal conductivity such as copper or brass can be selected, and the non-heated material can be efficiently heated.

[Brief description of the drawings]

FIG. 1 is a perspective view of a planar heating device according to the present invention.

FIG. 2 is a sectional view taken along the line XX in FIG.

FIG. 3 is an explanatory diagram of a heating resistor of the planar heating device of the present invention.

FIG. 4 is an explanatory diagram showing a relationship among a substrate, a heat transfer substrate, and a heating substrate of the planar heating device of the present invention.

FIG. 5 is a cross-sectional view of a conventional planar heating device.

FIG. 6 is an explanatory view of a mica heater of a conventional planar heating device.

FIG. 7 is an explanatory view of a conventional planar heating device using a heating resistor as a heat source.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base 21 Insulating film 22 Insulating film 3 Heat transfer base 4 Heating resistor 5 Heating base

Claims (1)

[Claims] An insulating film formed by curing a resin containing at least alumina as an inorganic powder on one surface;
A heat transfer substrate having a heating resistor fired on the insulating film; a substrate having at least a surface facing the heating resistor having an insulating property; and a heating resistor of the heat transfer substrate not being formed. A planar heating device comprising: a heating base material disposed on the other surface;