JP2002319481A - Hot plate unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hot plate unit which can stably heat an object such as a semiconductor wafer without the fear of generation of particle contamination or stop of current supply due to corrosion or the like of accessories even in the case of use under corrosive gas atmosphere. SOLUTION: The hot plate unit is constructed to include a ceramic board, at the lower part of which, an eddy current generating means having a conductor made of a plane-view spiral pattern is arranged. It is so constructed that eddy current is to be generated in the ceramic board through magnetism by supplying power to the above conductor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot plate unit mainly used in a semiconductor manufacturing process in the semiconductor industry.

[0002]

2. Description of the Related Art In a semiconductor manufacturing apparatus, deposition gas, etching gas, cleaning gas, etc.
Corrosive gases such as chlorine-based gas and fluorine-based gas are used. In the case of performing thermal CVD or the like, it is necessary to heat the semiconductor wafer. Therefore, usually, the semiconductor wafer is placed on a heater, and the above-described processing is performed while heating the semiconductor wafer.

As described above, when manufacturing a semiconductor, it is necessary to heat a semiconductor wafer or the like with a heater in a corrosive gas atmosphere. A ceramic heater in which a resistance heating element is provided on a ceramic substrate is used because there is a high possibility that the ceramic substrate itself is corroded.

Japanese Patent Application Laid-Open No. H11-40330 discloses such a ceramic heater in which a resistance heating element is disposed on the surface or inside of a substrate made of a nitride ceramic such as aluminum nitride.

However, in the above-described ceramic heater in which the resistance heating element is provided on the surface of the substrate, there is a problem that the resistance heating element is corroded by corrosive gas. If the resistance heating element is provided inside the ceramic substrate, there is no risk of corrosion of the resistance heating element itself, but external terminals are joined to the end of the resistance heating element through through holes and the like. Since the lead wire extends from the external terminal, the external terminal, the lead wire, and the solder (brazing material) connecting the through-hole and the external terminal are corroded by corrosive gas, and the external terminal There is a problem that dropouts and poor connection occur.

Further, when such corrosion of the external terminals occurs, there is another problem that particles generated by the corrosion may adhere to a semiconductor wafer or the like and cause particle contamination.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art. Even when the external terminal is used in a corrosive gas atmosphere, it is possible to prevent external terminals from falling off. Current supply is not stopped due to
It is an object of the present invention to provide a hot plate unit that can stably heat an object to be heated such as a semiconductor wafer and does not cause particle contamination on the semiconductor wafer.

[0008]

Means for Solving the Problems To achieve the above object, a hot plate unit of the present invention is a hot plate unit including a ceramic substrate,
Below the ceramic substrate, eddy current generating means having a conductor formed of a spiral pattern in a plan view is provided,
By supplying power to the conductor, an eddy current is generated in the ceramic substrate or a conductor inside or on the surface of the ceramic substrate via magnetism.

In the hot plate unit of the present invention, since there is no metal portion exposed on the surface (outside) of the ceramic substrate, even when the hot plate unit is used in a corrosive gas atmosphere, the supply of electric power due to the falling off of the external terminals or the like is performed. Thus, the object to be heated, such as a semiconductor wafer, can be stably heated without the risk of generation of heat.

An eddy current generating means having a conductor is provided below the ceramic substrate, and by supplying power to the conductor, the ceramic substrate or
Since it is configured to generate an eddy current in the conductor inside or on the surface of the ceramic substrate and generate heat to function as a ceramic heater, a resistance heating element is formed in the ceramic substrate, and a current is applied to the resistance heating element. As in the case where the ceramic substrate is supplied to generate heat, the object to be heated such as a semiconductor wafer can be heated using the ceramic heater.

The eddy current generating means does not become hot even when the ceramic substrate is heated, so that the eddy current generating means can be coated with a corrosion-resistant resin or the like, and the eddy current generating means is formed of a corrosive gas. Can be prevented from being corroded.

[0012] In the hot plate according to the present invention, it is preferable that the ceramic substrate is disposed inside a closed container, and the eddy current generating means is disposed outside the closed container.

When a process such as CVD is performed on a semiconductor wafer by introducing a corrosive gas into the inside of the closed container, the eddy current generating means is disposed outside the closed container.
There is no need to perform coating or the like, and an inexpensive eddy current generating means can be provided.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The hot plate unit of the present invention is a hot plate unit including a ceramic substrate, and has a conductor having a spiral pattern in a plan view below the ceramic substrate. An eddy current generating means is provided, and is configured such that an eddy current is generated in the ceramic substrate or a conductor inside or on the surface of the ceramic substrate through magnetism by supplying power to the conductor. It is characterized by being.

FIG. 1 is a cross-sectional view schematically showing one example of the hot plate unit of the present invention. FIG. 2 is a cross-sectional view of the ceramic substrate constituting the hot plate unit shown in FIG. .

In this hot plate unit 100,
The ceramic substrate 11 is provided in the airtight container 20. That is, a plurality of bolts 16 provided with a coil-shaped spring 17 are erected on the floor 21 of the airtight container 20, and the bolts 16 are inserted into through holes of the ceramic substrate 11. 11 is floor 2
It is supported and fixed at a distance of a certain distance from 1.
A heat-resistant and corrosion-resistant metal is used for the bolt 16 and the spring 17, and a washer 16 a made of a heat insulating material is interposed between the bolt 16 and the ceramic substrate 11.

Although the ceramic substrate 11 is supported and fixed by the bolts 16 and the springs 17 in FIG. 1, the ceramic substrate 11 may be installed on the floor 21 via a heat insulating material (support container) or the like. Since high conductivity is not required for the bolt 16 and the spring 17, a corrosion-resistant material can be used. However, if corrosion is not desired, the metal member is directly installed on the floor as described above to eliminate these metal members. May be.

As shown in FIG. 1, a shield layer 13 (conductor) is formed on the ceramic substrate 11. This is to prevent the semiconductor wafer 19 mounted on the ceramic substrate 11 via the support pins 14 from being affected by the magnetism generated from the eddy current generating plate 22 as the eddy current generating means. And this shield layer 13
Are also buried in the ceramic substrate 11 so as not to be affected by corrosive gas. Note that an eddy current may be generated in the shield layer 13 and used as a heating element.

The shield layer 13 is formed on the ceramic substrate 1
1 may be grounded via a bolt 16 penetrating therethrough. However, when the shield layer 13 is used as a heating element, grounding is not performed.

A through hole 15 for inserting a lifter pin (not shown) for supporting a semiconductor wafer 19 is formed in a portion near the center of the ceramic heater 10.

Further, an insulating layer (not shown) is formed on the surface of the ceramic substrate in order to secure insulation between the ceramic substrate and a semiconductor wafer mounted on the ceramic substrate.

An eddy current generating plate 22 as eddy current generating means is fixed below a floor 21 constituting the hermetic container 20 via a fixing member 27 such as a bolt. As shown in FIG. 3, the eddy current generating plate 22 is formed by forming a conductor 22b having a spiral pattern on a resin or ceramic plate 22a. An eddy current is generated in the ceramic substrate 11 due to a change in magnetism generated by applying an AC voltage or a pulse voltage to the conductor 22b having the spiral pattern. In addition, in order to ensure the uniformity of the temperature of the ceramic substrate 11, as shown in FIG. 3, the distance between the conductors 22b is reduced at the center of the plate-like body 22a, and the distance between the conductors 22b is reduced at the outer periphery. The conductors 22b may be formed so as to be dense.

The airtight container 20 is provided with a gas introduction pipe 25 and a gas discharge pipe 26 so that various kinds of processing can be performed by introducing a gas such as a corrosive gas into the inside. As corrosive gas, for example, CF ₄ , C ₂
F ₆ and the like.

Further, although not shown, the airtight container 20 can be actually divided into an upper container and a lower container.
When loading and unloading semiconductor wafers and the like, the containers are divided.

When heating the semiconductor wafer or the like, first, the hermetically sealed container 20 is divided, and the semiconductor wafer 19 is placed on the ceramic substrate 11 in the hermetically sealed container 20 via the support pins 14. In a closed state, for example, an AC voltage is applied to the eddy current generating plate 22 disposed below the hermetic container 20 via a lead wire 28. As a result, the magnetism greatly changes in the vicinity of the ceramic substrate 11, and an eddy current is generated in the ceramic substrate 11, and the ceramic substrate 11
Generates heat and functions as a ceramic heater. At this time, a corrosive gas is introduced, and CVD, cleaning, and the like are performed.

The material of the ceramic substrate constituting the hot plate unit of the present invention includes, for example, carbide ceramics and the like.

This is because the above-mentioned carbide ceramic has a smaller coefficient of thermal expansion than a metal and does not warp or be distorted by heating even if it is thin, so that the ceramic substrate can be made thin and light. In addition, since the heat capacity of the ceramic substrate is reduced by making the ceramic substrate thin and light, the ceramic substrate can be efficiently heated. Further, the carbide ceramic has a high thermal conductivity, so that the temperature of the ceramic substrate can be quickly raised and lowered.

Further, since the above-mentioned carbide ceramic has a higher conductivity at room temperature and a lower resistance in a high-temperature region as compared with, for example, a nitride ceramic or the like, the eddy current generating means has a predetermined electric conductivity. When the power is supplied, a large eddy current is generated in the ceramic substrate, and the ceramic substrate can efficiently generate heat.

As the above-mentioned carbide ceramic, for example,
Examples thereof include silicon carbide, boron carbide, titanium carbide, and tungsten carbide. Among them, it is desirable to use silicon carbide. This is because it has excellent heat resistance and mechanical properties, has high thermal conductivity, and has relatively high conductivity.

Further, the ceramic material may contain a sintering aid. As the sintering aid, for example,
Examples thereof include alkali metal oxides, alkaline earth metal oxides, and rare earth oxides. Among these sintering aids,
_{CaO, Y 2 O 3, Na} 2 O, Li 2 O, Rb 2 O are preferred. Their content is 0.1 to 20% by weight.
Is preferred. Further, it may contain alumina.

In the ceramic substrate made of the above material,
It is desirable that carbon be contained. The carbon content is preferably 100 to 5000 ppm. Carbon is classified into amorphous carbon and crystalline carbon. Amorphous carbon can be obtained, for example, by calcining a hydrocarbon consisting of only C, H, and O, preferably saccharides, in air, and using graphite powder or the like as crystalline carbon. be able to.

Carbon can be obtained by subjecting the acrylic resin to thermal decomposition under an inert atmosphere and then heating and pressurizing. By changing the acid value of the acrylic resin, the carbon (non-crystalline) can be obtained. Crystallinity) can be adjusted.

The ceramic substrate has a brightness of JI.
It is desirable that the value based on the definition of SZ8721 be N6 or less. This is because a material having such brightness is excellent in radiant heat and concealing property. Further, such a ceramic substrate can accurately measure the surface temperature by using a thermoviewer.

Here, the lightness N is defined as 0 for an ideal black lightness, 10 for an ideal white lightness, and the brightness of the color between these black lightness and white lightness. Each color is divided into ten so that the perception of the color is equal, and displayed by symbols N0 to N10. And the actual measurement is N0-N
The comparison is made with the color chart corresponding to No. 10. In this case, the first decimal place is 0 or 5.

The thickness of the ceramic substrate is 1.5 mm
And desirably not more than 25 mm. If the thickness of the ceramic substrate is 1.5 mm or less, the strength of the ceramic substrate may be reduced to cause breakage.
If the thickness exceeds 5 mm, the heat capacity of the ceramic substrate increases, and it takes time to cool.

As shown in FIG. 2, the ceramic substrate is preferably disk-shaped and has a diameter of 190 mm.
mm is desirable. This is because a large-diameter semiconductor wafer can be placed. It is particularly desirable that the diameter of the ceramic substrate is 12 inches (300 mm) or more. This is because it will become the mainstream of next-generation semiconductor wafers.

The porosity of the ceramic substrate is desirably 5% or less. Since the ceramic substrate having a high porosity has a low thermal conductivity, it takes a long time to transfer heat, and the responsiveness to electric power supplied to the eddy current generating means is extremely reduced.

Preferably, an insulating layer is formed on the surface of the ceramic substrate in order to ensure insulation between the ceramic substrate and a semiconductor wafer mounted on the ceramic substrate. The insulating layer may be formed on the entire surface of the ceramic substrate, or may be formed only on the surface on which the semiconductor wafer is mounted (hereinafter, wafer mounting surface).

The thickness of the insulating layer is 0.1 to 1000 μm.
m is desirable. The thickness of the insulating layer is 0.1μ
When the thickness is less than m, insulating properties cannot be ensured. On the other hand, when the thickness of the insulating layer exceeds 1000 μm, heat transfer to the semiconductor wafer is hindered.

As the oxide ceramic used as the insulating layer, for example, silica, alumina, mullite,
Cordierite, beryllia and the like. These ceramics may be used alone or in combination of two or more.

As a method of forming an insulating layer made of these materials, for example, a method of applying a glass powder paste and applying
A method of firing at 0 to 1000 ° C., a method of forming a coating layer on the surface of a ceramic substrate by spin coating using a sol solution obtained by hydrolyzing an alkoxide, followed by drying and firing, a sputtering method, a CVD method, and the like. . As a method for forming the insulating layer on a part of the surface of the ceramic substrate, screen printing or the like can be used.

The shield layer 13 embedded in the ceramic substrate can be obtained by firing a conductive paste. The conductive paste used here is not particularly limited, but preferably contains not only metal particles or conductive ceramic for ensuring conductivity, but also a resin, a solvent, a thickener, and the like.

As the metal particles, for example, noble metals (gold, silver, platinum, palladium), lead, tungsten, molybdenum, nickel and the like are preferable, and among them, noble metals (gold, silver, platinum, palladium) are more preferable. Also,
These may be used alone, but it is desirable to use two or more kinds in combination. This is because these metals are relatively hard to oxidize. As the conductive ceramic, for example,
Tungsten, molybdenum carbide and the like can be mentioned.
These may be used alone or in combination of two or more.

The particle size of these metal particles or conductive ceramic particles is preferably 0.1 to 100 μm. 0.1μ
If the particle size is too small, it is easily oxidized.
If the thickness exceeds μm, sintering becomes difficult and the resistance value increases.

Even if the shape of the metal particles is spherical,
It may be scaly. When these metal particles are used, they may be a mixture of the above-mentioned spheres and the above-mentioned flakes. When the metal particles are scaly, or a mixture of spherical and scaly, it is easy to hold the metal oxide between the metal particles, and the adhesion between the shield layer and the carbide ceramic is ensured. This is advantageous.

As the resin used for the conductor paste,
For example, an epoxy resin, a phenol resin, and the like can be given. Examples of the solvent include isopropyl alcohol. Examples of the thickener include cellulose and the like.

Further, a metal foil can be used as the shield layer. As the metal foil, a nickel foil and a stainless steel foil are desirable.

Further, the shield layer is 1/100 to 3 / th of the thickness of the ceramic substrate from the heating surface of the ceramic substrate.
Preferably it is at a distance of 5. If the shield layer is too close to the heated surface, the shield layer may be affected by corrosive gas as described above, and if the shield layer is separated from the heated surface, the effect of magnetism on the ceramic substrate may be reduced. This is because the number of portions increases, and the portion of the ceramic substrate through which current flows decreases, making it difficult to heat the ceramic substrate.

As shown in FIG. 2, the shield layer 13 may be formed as a solid layer, or may be formed in a mesh shape.

In the eddy current generating plate used as the eddy current generating means, for example, a solid conductor layer is formed on a resin substrate to which a copper foil is adhered, such as a copper-clad substrate, and then a spiral-shaped portion is left. It may be formed by performing an etching process as described above. As a material of the conductor layer, for example, copper, silver,
Aluminum is preferred. The frequency of the alternating current applied to the conductive layer of the eddy current generating plate is preferably 10 ³ to 10 ¹² Hz.

The airtight container 20 is desirably made of a metal having heat resistance and corrosion resistance such as nickel and stainless steel. The floor of the airtight container is preferably one which does not shield magnetism, for example, polyimide or the like. And a ceramic such as alumina.

In the present invention, a thermocouple can be embedded in a ceramic substrate as needed. The temperature of the ceramic substrate is measured with a thermocouple, and based on the data,
This is because it is possible to control the change in magnetism by changing the voltage and the amount of current supplied to the eddy current generating means, and to change the amount of eddy current generated in the ceramic substrate to control the temperature of the ceramic substrate.

The size of the junction of the thermocouple metal wires is preferably equal to or larger than the diameter of each metal wire and 0.5 mm or less. With such a configuration, the heat capacity of the junction is reduced, and the temperature is accurately and quickly converted to a current value. For this reason, the temperature controllability is improved and the temperature distribution on the heated surface of the wafer is reduced. Examples of the thermocouple include J
As listed in IS-C-1602 (1980),
K-type, R-type, B-type, E-type, J-type, and T-type thermocouples are exemplified.

In the ceramic heater of the present invention, an object to be heated such as a semiconductor wafer is placed and heated while being in contact with the wafer mounting surface of the ceramic substrate, and as shown in FIG. A concave portion, a through hole, or the like is formed in the substrate 11, and a pin having a spire or hemispherical tip is inserted and fixed in the concave portion or the like with the tip slightly projecting from the surface of the ceramic substrate. By supporting the object to be heated, such as, with the support pins 14, the object may be held at a constant distance from the ceramic substrate.
The distance between the heating surface and the wafer is preferably 5 to 5000 μm.

Further, as shown in FIG. 1, a plurality of through holes 15 are provided in the ceramic substrate 11, lifter pins (not shown) are inserted into the through holes 15, and the semiconductor wafer 19 is placed on the lifter pins. can do. In addition, the semiconductor wafer 19 can be transferred to the transfer device by raising and lowering the lifter pins, and the semiconductor wafer 19 can be received from the transfer device.

Although not shown in FIG. 1, the ceramic substrate is placed in a support container, and after the ceramic substrate is heated, a cooling gas such as air, nitrogen, or argon is supplied into the support container. The ceramic substrate may be cooled by pouring. In addition, when heating the ceramic substrate, a heated gas may be poured into the support container to shorten the time required to raise the temperature of the ceramic substrate.

Next, a method of manufacturing the ceramic heater constituting the hot plate unit of the present invention will be described with reference to FIG.

(1) Step of Producing Ceramic Substrate First, a ceramic powder such as a carbide ceramic is mixed with a binder, a solvent and the like to prepare a paste, and a green sheet 50 is produced using the paste.

Silicon carbide and the like can be used as the ceramic powder such as the above-mentioned carbides.
A sintering aid such as yttria or a compound containing Na or Ca may be added. The binder is preferably at least one selected from an acrylic binder, ethyl cellulose, butyl cellosolve, and polyvinyl alcohol.

Further, as the solvent, at least one selected from α-terpineol and glycol is desirable. A paste obtained by mixing these is shaped into a sheet by a doctor blade method to produce a green sheet. The thickness of the green sheet is preferably 0.1 to 5 mm.

(2) Step of Printing Conductor Paste on Green Sheet A metal paste for forming the shield layer 13 or a conductor paste containing conductive ceramic is printed on the green sheet 50 to form the conductor paste layer 130. I do. These conductive pastes contain metal particles or conductive ceramic particles.

The average particle diameter of the tungsten particles or molybdenum particles is preferably from 0.1 to 5 μm. If the average particle size is less than 0.1 μm or more than 5 μm, it is difficult to print the conductive paste. As such a conductive paste, for example, 85 to 87 parts by weight of metal particles or conductive ceramic particles; 1.5 to 10 parts by weight of at least one binder selected from acrylic, ethyl cellulose, butyl cellosolve, and polyvinyl alcohol; A composition (paste) in which 1.5 to 10 parts by weight of at least one solvent selected from α-terpineol and glycol is mixed.

(3) Green Sheet Laminating Step The green sheet 50 on which the conductor paste is not printed is
The green sheet 50 on which the conductive paste is printed is laminated on and under the green sheet 50 (see FIG. 4A) to form a green sheet laminate. At this time, the green sheets are stacked such that the shield layer formed on the ceramic substrate is formed at a position where the ratio of the distance from the heating surface of the ceramic substrate to the thickness of the ceramic substrate is within 60%.

(4) Green Sheet Laminate Firing Step The green sheet laminate is heated and pressed to sinter the green sheet and the internal conductive paste, thereby producing the ceramic substrate 11. The heating temperature is 1000-2
000 ° C. is preferable, and the pressure for pressurization is 10 to 20 MPa.
Is preferred. Heating is performed in an inert gas atmosphere. As the inert gas, for example, argon, nitrogen, or the like can be used (see FIG. 4B).

Next, for example, a solution such as an alumina sol or a silica sol prepared by hydrolyzing an alkoxide is applied to the heating surface 11a of the ceramic substrate 11 by a spin coating method, followed by drying and firing to form an insulating layer (see FIG. (Not shown). The insulating layer may be formed by a sputtering method or a CVD method, or the surface may be oxidized by heating the ceramic substrate in an oxidizing atmosphere to form an insulating layer. Further, before firing, an insulating layer may be formed by applying a glass paste to a green sheet as an uppermost layer in advance.

Next, a semiconductor wafer 1 was placed on the obtained sintered body.
9 through which a lifter pin for supporting the 9 is inserted
If necessary, a bottomed hole (not shown) for burying a temperature measuring element such as a thermocouple is formed (see FIG. 4C).

The step of forming the through holes and the like may be performed on the green sheet laminate, but is preferably performed on the sintered body. This is because during the sintering process, there is a possibility of deformation.

The through holes and the like can be formed by performing blasting such as sand blasting after surface polishing. Further, if necessary, a thermocouple (not shown) as a temperature measuring element is attached to the bottomed hole (not shown) with a silver solder, a gold solder, or the like, and sealed with a heat-resistant resin such as polyimide. Manufacturing of No. 10 is completed.

Further, the ceramic heater may be produced by a method of producing a formed body using granules containing ceramic powder and sintering it. In this case, first, if necessary, a sintering aid such as yttria (Y ₂ O ₃ ) or B ₄ C, a compound containing Na or Ca, a binder, or the like is added to the above-mentioned ceramic powder such as a carbide such as silicon carbide. After blending to prepare a slurry, the slurry is granulated by a method such as spray drying.

Next, the granules are placed in a mold and pressed. At this time, a metal foil serving as a shield layer is placed inside and pressurized to produce a plate-shaped or the like formed green (green). The formed body is heated, fired and sintered, and further processed to manufacture a ceramic heater.

Hereinafter, description will be made in accordance with embodiments.

(Embodiment 1) Hot plate unit (FIG. 1)
(1) 100 parts by weight of silicon carbide powder (average particle size: 1.1 μm, manufactured by Yakushima Denko) baked at 500 ° C. for 1 hour in air, 4 parts by weight of carbon, 11.5 parts by weight of an acrylic binder Using a paste obtained by mixing 0.5 parts by weight of a dispersant and 53 parts by weight of alcohol composed of 1-butanol and ethanol, molding was performed by a doctor blade method to obtain a green sheet 50 having a thickness of 0.47 mm. And
Of these green sheets, a glass paste was applied to the uppermost green sheet. (2) Next, these green sheets 50 are placed at 80 ° C. for 5 seconds.
Let dry for hours.

(3) 100 parts by weight of tungsten carbide particles having an average particle diameter of 1 μm, acrylic binder 3.0
By weight, 3.5 parts by weight of the α-terpineol solvent and 0.3 parts by weight of the dispersant were mixed to prepare a conductor paste A. The conductive paste A was printed on the green sheet 50 by screen printing to form a conductive paste layer serving as a shield layer. The printing pattern was a circular pattern as shown in FIG.

(4) The green sheet 50 on which the conductor paste A is not printed is further placed on the green sheet 50 on which the conductor paste layer serving as the shield layer is formed (heating surface).
30 sheets on the lower side and 20 sheets on the lower side.
The laminate was formed by pressure bonding at a pressure of MPa (80 kg / cm ² ) (FIG. 4A).

(5) Next, the obtained laminate was degreased in nitrogen gas at 600 ° C. for 5 hours, and at 1890 ° C. under a pressure of 15 M
Hot pressing for 3 hours at Pa (150 kg / cm ² )
A ceramic plate having a thickness of 3 mm was obtained. This is 310m
m and a ceramic heater 10 having a shield layer 13 therein (see FIG. 4B).

(6) Next, after polishing the ceramic plate obtained in (5) with a diamond grindstone, lifter pins 16 (diameter: 5) for carrying a silicon wafer or the like are used.
mm) for insertion of a through hole 15 (diameter: 5.6 m)
m) were formed (see FIG. 4C). The through-holes 15 were formed at equal intervals on a circumference having a diameter of 116 mm, which is concentric with the ceramic substrate 11.
Further, a bottomed hole for inserting a thermocouple was formed, and a plurality of thermocouples for temperature control were embedded in the bottomed hole. Further, a concave portion was formed on the heating surface of the ceramic substrate 11, and the support pin 14 was fitted. At this time, the support pins 14 protruded 100 μm from the heating surface.

Thereafter, as shown in FIG. 1, after the hermetically sealed container 20 is divided, the ceramic heater 10 is supported and fixed to the floor 21 thereof through bolts 16 and springs 17, and the silicon The wafer was placed.

Further, an eddy current generating plate 22 in which a spiral conductive layer 22b is formed by etching a copper-clad substrate for a printed wiring board is provided below the hermetic container 20, and a frequency of 1 GHz is provided. An AC voltage was applied to generate an eddy current in the shield layer 13 to generate heat and heat the silicon wafer.

Example 2 Production of Hot Plate Unit (See FIG. 1) (1) 100 parts by weight of silicon carbide powder (average particle size 1.1 μm, manufactured by Yakushima Electric Works) fired at 500 ° C. for 1 hour in air; 10. 4 parts by weight of carbon, acrylic resin binder
5 parts by weight were mixed, put into a hexagonal column forming mold, and put in a nitrogen atmosphere at 1890 ° C. under a pressure of 15 MPa (150 kg / cm).
Hot pressing was performed for 3 hours under the conditions of ² ) to obtain a silicon carbide sintered body. Note that a metal foil to be a shield layer was embedded in a mold, and the position of the shield layer after firing was set to a position 1 mm from the heating surface. This was cut into a 310 mm disc to obtain a ceramic heater 10 having a shield layer 13 inside.

(2) Next, after polishing the ceramic plate obtained in (1) with a diamond grindstone, the heating surface of the ceramic substrate 11 is coated with tetraethyl silicate 25
A mixture consisting of 3 parts by weight of ethanol, 37.6 parts by weight of ethanol, 0.3 part by weight of hydrochloric acid, and 23.5 parts by weight of water was hydrolyzed with stirring for 24 hours, and a polymerized sol solution was applied by spin coating. And then dried at 80 ° C. for 5 hours,
By sintering at 1000 ° C. for 1 hour, the heating surface of the ceramic substrate 11 made of silicon carbide is
An insulating layer (not shown) made of O ₂ was formed.

Thereafter, three through holes 15 (diameter: 5.6 mm) for inserting lifter pins (not shown) (diameter: 5 mm) for carrying a silicon wafer or the like were formed. The through-holes 15 were formed at equal intervals on a circumference having a diameter of 116 mm, which is concentric with the ceramic substrate 11.

Further, a bottomed hole for inserting a thermocouple was formed, and a plurality of thermocouples for temperature control were embedded in the bottomed hole. Further, a concave portion was formed on the heating surface of the ceramic substrate 11, and the support pin 14 was fitted. At this time, the support pins 14 protruded 100 μm from the heating surface.

Thereafter, as shown in FIG. 1, after the hermetically sealed container 20 is divided, the ceramic heater 10 is supported and fixed to the floor 21 thereof through the bolts 16 and the springs 17 and the silicon heater is supported through the support pins 14. The wafer was placed.

Further, an eddy current generating plate 22 in which a spiral conductive layer 22b is formed by etching a copper-clad substrate for a printed wiring board is provided below the hermetic container 20, and a frequency of 1 GHz is provided. An AC voltage was applied to generate an eddy current in the ceramic substrate 11 itself and the shield layer 13 made of silicon carbide, generating heat and heating the silicon wafer.

(Comparative Example 1) Production of hot plate unit (1) 100 parts by weight of aluminum nitride powder (manufactured by Tokuyama Corporation, average particle size: 1.1 μm), yttria (average particle size: 0.1 μm)
4 μm) 4 parts by weight, acrylic binder 11.5 parts by weight,
Using a paste obtained by mixing 0.5 part by weight of a dispersant and 53 parts by weight of alcohol composed of 1-butanol and ethanol, the mixture was molded by a doctor blade method to a thickness of 0.4.
A 7 mm green sheet 50 was obtained.

(2) Next, this green sheet 50 is
After drying at 0 ° C. for 5 hours, a diameter of 1.
8 mm, 3.0 mm and 5.0 mm through holes were formed, respectively. These through holes are a portion to be a through hole for inserting a lifter pin, a portion to be a through hole, and the like. (3) 100 parts by weight of tungsten carbide particles having an average particle diameter of 1 μm, 3.0 parts by weight of an acrylic binder, α-
A conductor paste A was prepared by mixing 3.5 parts by weight of a terpineol solvent and 0.3 parts by weight of a dispersant.

Tungsten particles 10 having an average particle diameter of 3 μm
A conductive paste B was prepared by mixing 0 parts by weight, 1.9 parts by weight of an acrylic binder, 3.7 parts by weight of an α-terpineol solvent and 0.2 part by weight of a dispersant.

The conductor paste A was printed on a green sheet by screen printing to form a conductor paste layer to be a resistance heating element. The printing pattern was such that resistance heating elements composed of a repeating pattern of U-shaped bent lines were arranged concentrically. In addition, the conductive paste B was filled in the through-hole portion to be a through-hole. On the green sheet after the above-mentioned processing, 37 sheets of unprinted green sheets are laminated on the upper side (heating surface) and 13 sheets on the lower side.
The laminated body was produced by integrating at 30 ° C. and a pressure of 8 MPa (80 kg / cm ² ).

(4) Next, the obtained laminate was degreased in nitrogen gas at 600 ° C. for 5 hours, and at 1890 ° C. under a pressure of 15 M
It was hot-pressed at Pa for 10 hours to obtain an aluminum nitride plate having a thickness of 3 mm. This was cut into a 310 mm disk shape to obtain a ceramic substrate having a 6 mm thick, 10 mm wide resistance heating element inside. The size of the through hole was 0.2 mm in diameter and 0.2 mm in depth.

(5) Next, the plate obtained in the above (4) is polished with a diamond grindstone, and then a mask is placed thereon.
A bottomed hole for embedding a thermocouple was provided on the surface by blasting with SiC or the like.

(6) Further, the diameter is 5 m by drilling.
m, a blind hole having a depth of 0.5 mm was formed, a W-made washer was fitted into the blind hole, a lead wire was inserted into the center hole of the washer, and then a Ni-Au alloy (Au: 81.5% by weight, These wereher and lead wire were fixed to a ceramic substrate by heating and reflowing at 970 ° C. using a gold brazing filler made of Ni: 18.4% by weight and impurities: 0.1% by weight.

(7) Next, the production of the ceramic heater in which the temperature measuring element was embedded in the bottomed hole and the resistance heating element was embedded was completed. (8) Next, this ceramic heater is fitted and fixed in an aluminum support container via a heat insulating member (thickness: 1 mm) made of PTFE having an annular shape to form a hot plate unit. This hot plate unit was placed in an airtight container.

Comparative Example 2 A hot plate was prepared in the same manner as in Comparative Example 1, except that a ceramic tubular body was joined to the bottom surface of the ceramic substrate, and lead wires and the like were provided inside the tubular body. The unit was manufactured. In addition, nitrogen gas was introduced as an inert gas into the inside of the cylindrical body.

The hot plate units obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were evaluated as follows.

Evaluation method

(1) Corrosion resistance test using corrosive gas CF ₄ gas was introduced into a closed container so that the concentration became 10 vol%, and the ceramic heater was heated at 300 ° C.
For 24 hours, and the degree of corrosion of the ceramic heater and attached parts was observed.

(2) Uniformity of Temperature of Silicon Wafer After the temperature of the ceramic heater was raised to 300 ° C., the silicon wafer was mounted on the ceramic heater, and a thermoviewer (IR-16-012-001 manufactured by Nippon Datum Co., Ltd.) was used.
According to 2), the maximum temperature and the minimum temperature of the silicon wafer were measured, and the temperature difference was obtained. Table 1 shows the results.

[0097]

[Table 1]

As shown in Table 1, in the hot plate units according to Examples 1 and 2 and Comparative Example 2, although the ceramic heater and surrounding accessories (bolts, springs, etc.) did not corrode, On the other hand, in the hot plate unit according to Comparative Example 1, corrosion occurred in the external terminals and the solder layer.

In the hot plate units according to Examples 1 and 2 and Comparative Example 1, the temperature difference between the maximum temperature and the minimum temperature was small and almost no temperature distribution occurred. In the hot plate unit, as shown in Table 1, the temperature difference between the maximum temperature and the minimum temperature was large. This is because the ceramic cylindrical body is bonded, so that the inert gas is introduced into the cylindrical body to dissipate heat into the cylindrical body and to reduce the joint between the ceramic substrate and the cylindrical body. It is considered that the temperature distribution was generated due to the heat dissipation through the substrate.

[0100]

As described above, in the hot plate unit according to the present invention, since the resistance heating element is not provided on the ceramic substrate and no external terminal is provided, the hot plate unit is used in a corrosive gas atmosphere. However, no corrosion occurs in the ceramic heater.

An eddy current generating means having a conductor formed of a spiral pattern in a plan view is provided below the ceramic substrate, and by supplying power to the conductor, the ceramics are magnetized via magnetism. When an electric current is supplied directly to the resistance heating element in the ceramic heater because it is configured to generate an eddy current in the conductor inside or on the surface of the substrate or ceramic substrate and generate heat to function as a ceramic heater In the same manner as described above, an object to be heated such as a semiconductor wafer can be heated using this ceramic heater.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing a hot plate unit of the present invention.

FIG. 2 is a sectional view taken along line AA of a ceramic heater constituting the hot plate unit.

FIG. 3 is a plan view schematically showing an eddy current generating plate as one of the eddy current generating means.

FIG. 4 is a sectional view schematically showing a part of a manufacturing process of a ceramic heater constituting the hot plate unit.

[Explanation of symbols]

 Reference Signs List 10 ceramic heater 11 ceramic substrate 11a heating surface 13 shield layer 14 support pin 15 through hole 16 bolt 16a washer 17 spring 19 semiconductor wafer (silicon wafer) 20 hermetic container 21 floor 22 eddy current generating plate 22a plate 22b conductive layer 25 Gas inlet pipe 26 Gas exhaust pipe 27 Fixture 28 Lead wire 100 Hot plate unit

Claims (3)

[Claims] 1. A hot plate unit including a ceramic substrate, wherein eddy current generating means having a conductor having a spiral pattern in a plan view is disposed below the ceramic substrate. A hot plate unit characterized in that: 2. The hot plate unit according to claim 1, wherein the ceramic substrate is disposed inside a hermetic container, while the eddy current generating means is disposed outside the hermetic container. . 3. The hot plate unit according to claim 1, wherein a conductor is formed inside or on the surface of the ceramic substrate.