JP2003208967A - Hot plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hot plate in which the temperature of its heating surface can be measured more correctly by a thermo-viewer since the infrared transmittance of a ceramic board is as low as 10% or less. <P>SOLUTION: The hot plate which consists of the ceramic board, in which an electricity conductor layer has been formed on the surface or in the inside, and the transmittance of the wavelength of infrared rays of the above ceramic board is 0 or 10% or less. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a hot plate mainly used for manufacturing and inspecting semiconductors.

[0002]

2. Description of the Related Art In semiconductor manufacturing / inspection equipment including etching equipment and chemical vapor deposition equipment, heaters and wafer probers using metal base materials such as stainless steel and aluminum alloy have been used. Has been.

However, such a metal heater is
There were the following problems. First of all, because it is made of metal,
The thickness of the heater plate should be as thick as about 15 mm. This is because, in a thin metal plate, warping, distortion, etc. may not occur due to thermal expansion due to heating, and the silicon wafer placed on the metal plate may be damaged or tilted. However, when the thickness of the heater plate is increased, there is a problem that the weight of the heater becomes heavy and the heater becomes bulky.

Further, the temperature of a surface (hereinafter referred to as a heating surface) for heating an object to be heated such as a silicon wafer is controlled by changing the voltage and the amount of current applied to the resistance heating element. Since it is thick, the temperature of the heater plate does not quickly follow changes in voltage and current amount, and there is a problem that temperature control is difficult.

Therefore, as described in JP-A-11-40330, a nitride ceramic or a carbide ceramic having a high thermal conductivity and a high strength is used as a substrate, and a plate-shaped body (ceramic) made of these ceramics is used. A hot plate has been proposed in which a resistance heating element formed by sintering metal particles is provided on the surface of a substrate. Further, Japanese Patent Laid-Open No. 9-48668 discloses an aluminum nitride sintered body containing carbon.

[0006]

However, in this ceramic substrate, when an attempt is made to measure the surface temperature of a surface (hereinafter referred to as a heating surface) for heating an object to be heated such as a silicon wafer with a thermoviewer, infrared rays are transmitted. Therefore, infrared rays emitted from the heating element are measured, and there is a problem that the temperature of the heating surface cannot be accurately measured.

[0007]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that a ceramic substrate contains a predetermined amount of carbon, that is, a ceramic powder and a resin are pressed. After molding and forming a green body, degreasing and firing reduce the crystallinity of carbon to increase the infrared absorption efficiency, and the carbon tends to remain as a resin in the degreasing step, and the crystalline The inventors have found that a ceramic substrate having an infrared transmittance of 0 or 10% or less can be manufactured by selecting a low one, and have completed the present invention.

That is, the present invention is a hot plate in which a conductor layer is formed on the surface or inside of a ceramic substrate, wherein the ceramic substrate has a transmittance of infrared rays having a wavelength of 2500 nm of 0 or 10% or less. Is
The hot plate has a lightness of N4 or less according to JIS Z 8721.

According to the hot plate of the present invention, since the ceramic substrate has an infrared ray, particularly an infrared ray transmittance at a wavelength of 2500 nm of 10% or less, it does not transmit infrared rays radiated from the heating element, so that the hot plate heating surface is When measuring the surface temperature with a thermoviewer, the infrared rays from the heating element do not interfere. Therefore, the measurement wavelength of the thermoviewer can be set from around 2500 nm, and it becomes possible to capture infrared rays of a relatively short wavelength generated at low temperature, and the temperature of the heating surface can be measured in a wide temperature range from low temperature to high temperature. It becomes possible to do.

Further, since the brightness according to JIS Z 8721 is blackened to N4 or less, black body radiation can be utilized, high radiant heat can be obtained, and heating of the ceramic substrate by a resistance heating element or the like can be efficiently performed. It can be carried out. Further, when the resistance heating element is formed inside, the resistance heating element can be hidden.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The hot plate of the present invention will be described below with reference to the embodiments. The hot plate of the present invention is a hot plate in which a conductor layer is formed on the surface or inside a ceramic substrate, and the ceramic substrate has an infrared wavelength transmittance of 0 or 10% or less.

The wavelength of infrared rays to be measured is 760 to 260
0 nm can be used, but 2500 nm is preferable. Since it is an intermediate region between the near infrared region (760-2500 nm) and the mid-infrared region (2500-25000 nm),
This is because it serves as a guide for the transmittance of both regions. Further, near infrared rays are easily generated at a relatively low temperature, but by setting the transmittance in the near infrared region to 10% or less, low temperature to high temperature (10
The temperature of the heating surface of 0 to 800 ° C.) can be accurately measured by a thermoviewer.

The infrared transmittance of the ceramic substrate is
The reason why it is set to 0 or 10% or less is that if the above-mentioned transmittance exceeds 10%, infrared rays from the heating element become the background, the temperature of the heating surface cannot be measured, and an error occurs in the measured value. It is possible to measure by performing the correction process in consideration of the error, but it is complicated because the correction processing software is required,
Not a practical hot plate. The optimum transmittance is 5% or less. The light transmittance is a value when the light transmittance of a ceramic substrate having a thickness of 0.5 mm is measured.

Further, the brightness of the ceramic substrate is JIS
It is desirable that the value based on the regulation of Z 8721 is N4 or less. This is because those having such brightness are excellent in radiant heat amount and concealing property. In addition, a ceramic substrate with such characteristics enables accurate surface temperature measurement by a thermoviewer, and by using this thermoviewer, the temperature of the surface (heating surface) that heats the silicon wafer of the ceramic substrate can be controlled. Will be easier.

Here, the lightness N is such that the ideal lightness of black is 0 and the ideal lightness of white is 10, and the brightness of the color is between the lightness of black and the lightness of white. Each color is divided into 10 so that the perception of is equal to each other, and is displayed by symbols N0 to N10. And the actual measurement is N0-N
The color chart corresponding to 10 is compared. In this case, the first decimal place is 0 or 5.

FIG. 1 is a bottom view schematically showing an example of the hot plate of the present invention, and FIG. 2 is a partially enlarged sectional view schematically showing a part of the hot plate shown in FIG.
In this hot plate, a resistance heating element is formed on the bottom surface of the ceramic substrate.

As shown in FIG. 1, the ceramic substrate 11
Are formed in a disk shape, and the ceramic substrate 11
A resistance heating element 12a made of a bent circuit is formed in a portion close to the peripheral portion on the bottom surface 11b of the bottom surface 11b, and resistance heating elements 12b to 12 having a substantially concentric shape are formed in the inner portion thereof.
d is formed and these circuits are combined to form the heating surface 1
It is designed so that the temperature at 1a is uniform.

Further, the resistance heating elements 12a to 12d are formed with a metal coating layer 120 for preventing oxidation, and input / output end portions 13 are formed at both ends of the metal coating layer 120. As shown in FIG. 2, the external terminals 17 are joined using solder or the like. Further, a socket 170 provided with wiring is connected to the external terminal 17 so as to be connected to a power source.

Further, a bottomed hole 14 for inserting the temperature measuring element 18 is formed in the ceramic substrate 11, and a through hole 15 for inserting the lifter pin 16 is provided in a portion near the center. Has been.

The lifter pin 16 is configured such that a silicon wafer 19 can be placed on the lifter pin 16 and moved up and down. This allows the silicon wafer 19 to be transferred to a transfer machine (not shown) or transferred from the transfer machine to the silicon. Wafer 19
The silicon wafer 19 is placed on the heating surface 11a of the ceramic substrate 11 and heated, or the silicon wafer 19 is supported and heated while being separated from the heating surface 11a by 50 to 2000 μm. Is able to.

A state in which a through hole or a recess is provided in the ceramic substrate 11, and a support pin having a pointed or hemispherical tip is inserted into the through hole or the recess, and then the support pin is slightly projected from the ceramic substrate 11. Alternatively, the silicon wafer 19 may be heated by being fixed at a distance of 50 to 2000 μm from the heating surface 11a by supporting the silicon wafer 19 with the support pins.

FIG. 3 is a partially enlarged sectional view schematically showing another example of the hot plate of the present invention. In this hot plate, a resistance heating element is formed inside a ceramic substrate.

Although not shown, similar to the ceramic heater shown in FIG. 1, the ceramic substrate 21 is formed in a disk shape, and the resistance heating element 22 is provided inside the ceramic substrate 21. It is formed by a pattern similar to the pattern shown in, that is, a pattern in which concentric circles and bending lines are combined.

A through hole 28 is formed immediately below the end of the resistance heating element 22, and a bag hole 27 for exposing the through hole 28 is formed on the bottom surface 21b. The bag hole 27 has an external terminal. 23 is inserted and brazing material 24
Are joined together. Although not shown in FIG. 3,
Like the hot plate shown in FIG. 1, a socket having a conductive wire is attached to the external terminal 23,
This conductive wire is connected to a power source or the like.

The hot plate of the present invention is, for example, as shown in FIG.
3 to 3 have the configurations shown in FIG. In the following, each member constituting the hot plate will be sequentially described in detail.

The ceramic material forming the hot plate is not particularly limited, and examples thereof include nitride ceramics, carbide ceramics, oxide ceramics and the like.

Examples of the nitride ceramics include metal nitride ceramics such as aluminum nitride, silicon nitride, boron nitride and titanium nitride. Further, as the above-mentioned carbide ceramics, metal carbide ceramics,
For example, silicon carbide, zirconium carbide, titanium carbide,
Examples thereof include tantalum carbide and tungsten carbide.

Examples of the oxide ceramics include metal oxide ceramics such as alumina, zirconia, cordierite and mullite. These ceramics may be used alone or in combination of two or more.

Among these ceramics, nitride ceramics and carbide ceramics are more preferable than oxide ceramics. This is because the thermal conductivity is high. Aluminum nitride is most preferable among the nitride ceramics. This is because the highest thermal conductivity is 180 W / m · K.

Generally, it is preferable that the nitride ceramic contains a metal oxide. This is because these act as a sintering aid, facilitate the progress of sintering, and reduce the internal pores, thereby improving the withstand voltage, mechanical properties, and the like of the ceramic substrate.

Examples of the metal oxides include yttria (Y ₂ O ₃ ), alumina (Al ₂ O ₃ ), rubidium oxide (Rb ₂ O), lithium oxide (Li ₂ O), calcium carbonate (CaCO ₃ ). Etc. The addition amount of these metal oxides is preferably 1 to 10 parts by weight with respect to 100 parts by weight of the nitride ceramic.

The ceramic substrate forming the hot plate of the present invention has an infrared transmittance of 0 or 10% or less, and preferably has a brightness of N4 or less according to JIS Z 8721.

The ceramic substrate having such characteristics has 100 to 5000 p of carbon in the ceramic substrate.
It is obtained by containing pm. There are two types of carbon, amorphous and crystalline.Amorphous carbon can suppress a decrease in volume resistivity of a ceramic substrate at high temperatures, and can absorb light in the infrared region. It is advantageous because it is easy to do and does not allow it to pass through.

Amorphous carbon is, for example, C, H or O.
Hydrocarbons consisting solely of, preferably sugars, can be obtained by calcining in air. Note that examples of crystalline carbon include graphite powder and the like.

In addition, after the green sheet laminate containing an acrylic resin is thermally decomposed in an inert atmosphere, it is heated,
A ceramic substrate containing carbon can be obtained by applying pressure, and the degree of crystallinity (amorphousness) can be adjusted by changing the acid value of the acrylic resin. The acrylic resin can be added as a binder. As the acrylic resin binder, for example, SA-545 series manufactured by Mitsui Chemicals, or KC-600 series manufactured by Kyoeisha can be used.

The porosity of the ceramic substrate is 5
% Or less, it is desirable that the maximum pore diameter is 50 μm or less. When the porosity exceeds 5%, the number of pores in the ceramic dielectric film increases and the pore diameter also increases, and the ceramic substrate having such a structure has a reduced withstand voltage and mechanical characteristics. Because it will be.

When the pore diameter of the maximum pore exceeds 50 μm, the withstand voltage, mechanical characteristics, etc. also deteriorate.
The porosity is more preferably 0 or 3% or less, and the pore size of the maximum pores is more preferably 0 or 10 μm or less. The measurement of the pore diameter of the maximum pores is performed by preparing five samples, mirror-polishing the surfaces thereof, and photographing the surfaces at 10 sites with an electron microscope at a magnification of 2000 to 5000 times. Then, the maximum pore diameter is selected from the photographed pictures, and the average of 50 shots is taken as the maximum pore diameter.

The porosity is measured by the Archimedes method. Pulverize the sintered body and put the pulverized product in an organic solvent or mercury to measure the volume, calculate the true specific gravity from the weight and volume of the pulverized product, and calculate the porosity from the true specific gravity and the apparent specific gravity. Of.

In the hot plate according to the present invention, normally, as shown in FIG.
As described above, a resistance heating element is provided, but the temperature control means may be a Peltier element in addition to the resistance heating element.

When the resistance heating element is provided inside the ceramic substrate, a plurality of layers may be provided. In this case, it is desirable that the patterns of the respective layers are formed so as to complement each other, and the pattern is formed in any of the layers as viewed from the heating surface. For example, a structure in which staggered arrangement is provided.

Examples of the resistance heating element include a sintered body of metal or conductive ceramic, a metal foil, a metal wire and the like. The metal sintered body is preferably at least one selected from tungsten and molybdenum. This is because these metals are relatively difficult to oxidize and have a resistance value sufficient to generate heat.

As the conductive ceramic, at least one selected from carbides of tungsten and molybdenum is used.
Seeds can be used. Further, when the resistance heating element is formed on the bottom surface of the ceramic substrate, it is desirable to use a noble metal (gold, silver, palladium, platinum) or nickel as the metal sintered body. Specifically, silver, silver-palladium, or the like can be used. The metal particles used in the metal sintered body may be spherical, flaky, or a mixture of spherical and flaky.

A metal oxide may be added to the metal sintered body. The reason for using the above metal oxide is to bring the ceramic substrate and the metal particles into close contact with each other. The reason why the metal oxide improves the adhesion between the ceramic substrate and the metal particles is not clear, but a slight oxide film is formed on the surface of the metal particles. Of course, even in the case of a non-oxide ceramic, an oxide film is formed on the surface thereof. Therefore, it is considered that this oxide film may be sintered and integrated on the surface of the ceramic substrate via the metal oxide, and the metal particles and the ceramic substrate may adhere to each other.

Examples of the above metal oxide include, for example, oxidation.
Lead, zinc oxide, silica, boron oxide (B ₂ O₃ ), Al
At least one selected from Mina, Yttria, and Titania
Seeds are preferred. These oxides are the resistance value of the resistance heating element.
Between the metal particles and the ceramic substrate without increasing the
This is because the adhesion can be improved.

The amount of the above metal oxide is preferably 0.1 part by weight or more and less than 10 parts by weight with respect to 100 parts by weight of the metal particles. By using a metal oxide in this range,
This is because the resistance value does not become too large and the adhesion between the metal particles and the ceramic substrate can be improved.

Further, the proportion of lead oxide, zinc oxide, silica, boron oxide (B ₂ O ₃ ), alumina, yttria, and titania is such that when the total amount of metal oxides is 100 parts by weight, lead oxide is 1 to 1. 10 parts by weight, 1 to 30 parts by weight of silica, 5 to 50 parts by weight of boron oxide, 20 to 7 of zinc oxide.
0 parts by weight, alumina 1 to 10 parts by weight, yttria 1
-50 parts by weight and titania 1-50 parts by weight are preferred.
However, it is desirable that the total amount of these components be adjusted within a range not exceeding 100 parts by weight. This is because these ranges can improve the adhesion to the ceramic substrate.

When the resistance heating element is provided on the bottom surface of the ceramic substrate, the surface of the resistance heating element 12 has a metal coating layer 120.
It is desirable to be coated with (see FIG. 2). The resistance heating element 12 is a sintered body of metal particles, and if exposed, it is easily oxidized, and the resistance value changes due to this oxidation. Therefore, by coating the surface with the metal coating layer 120, oxidation can be prevented.

The metal coating layer 120 has a thickness of 0.1 to 10
μm is desirable. This is because the resistance heating element can be prevented from being oxidized without changing the resistance value of the resistance heating element. The metal used for coating may be a non-oxidizing metal. Specifically, at least one selected from gold, silver, palladium, platinum and nickel is preferable. Of these, nickel is more preferable. This is because the resistance heating element needs a terminal for connecting to a power supply, and this terminal is attached to the resistance heating element via solder, but nickel prevents heat diffusion of the solder. A terminal pin made by Kovar can be used as the connection terminal.

When the resistance heating element is formed inside the heater plate, the surface of the resistance heating element is not oxidized, so that coating is unnecessary. When the resistance heating element is formed inside the heater plate, a part of the surface of the resistance heating element may be exposed.

As the metal foil used as the resistance heating element, a nickel foil or a stainless foil is preferably patterned to form the resistance heating element by etching or the like. The patterned metal foil may be laminated with a resin film or the like. Examples of the metal wire include a tungsten wire and a molybdenum wire.

When a Peltier element is used as the temperature control means, heat is generated by changing the direction of current flow.
This is advantageous because both cooling can be performed. The Peltier element is formed by connecting p-type and n-type thermoelectric elements in series and joining them to a ceramic plate or the like. Examples of the Peltier element include silicon / germanium-based materials, bismuth / antimony-based materials, lead / tellurium-based materials, and the like.

In the hot plate of the present invention, when the resistance heating element 22 is provided inside the ceramic substrate, a connecting portion (through hole) for connecting these to the external terminal.
28 is required. The through hole 28 is formed by filling a refractory metal such as tungsten paste or molybdenum paste, or a conductive ceramic such as tungsten carbide or molybdenum carbide.

The diameter of the connecting portion (through hole) 28 is preferably 0.1 to 10 mm. While preventing disconnection
This is because cracks and distortion can be prevented. The external terminal pins 23 are connected using the through holes as connection pads (see FIG. 3).

Connection is made with solder or brazing material. As a brazing material, silver brazing, palladium brazing, aluminum brazing,
Use gold wax. Au-Ni alloy is preferable for gold brazing. This is because the Au-Ni alloy has excellent adhesion to tungsten.

The Au / Ni ratio is [81.5 to 82.
5 (wt%)] / [18.5 to 17.5 (wt%)] is desirable. The thickness of the Au—Ni layer is preferably 0.1 to 50 μm. This is because the range is sufficient to secure the connection.
Moreover, it is 500 to 1000 at a high vacuum of 10 ⁻⁶ to 10 ⁻⁵ Pa.
When used at a high temperature of ℃, the Au-Cu alloy deteriorates,
The Au-Ni alloy is advantageous because it does not cause such deterioration.
The total amount of impurity elements in the Au-Ni alloy is 100
When the amount is parts by weight, it is preferably less than 1 part by weight.

In the present invention, a thermocouple can be embedded in the bottomed hole 12 of the ceramic substrate 1 if necessary. This is because the temperature of the resistance heating element can be measured with a thermocouple and the temperature can be controlled by changing the amount of voltage and current based on the data. The size of the joining portion of the metal wire of the thermocouple is equal to or larger than the wire diameter of each metal wire, and is preferably 0.5 mm or less. With such a configuration, the heat capacity of the joint portion is reduced, and the temperature is converted into a current value accurately and quickly. Therefore, the temperature controllability is improved and the temperature distribution on the heating surface of the wafer is reduced. As the thermocouple, for example,
As described in JIS-C-1602 (1980), K-type, R-type, B-type, S-type, E-type, J-type and T-type thermocouples can be mentioned.

FIG. 4 is a sectional view schematically showing a support container 30 for disposing the hot plate (ceramic substrate) having the above structure. The ceramic substrate 11 is fitted into the support container 30 via a heat insulating material 35, and is fixed by using a bolt 38 and a pressing metal fitting 37. Further, a guide tube 32 communicating with the through hole is provided in the portion of the ceramic substrate 11 where the through hole 15 is formed. Further, a refrigerant outlet 30a is formed in the support container 31, the refrigerant is blown from the refrigerant injection pipe 39, and is discharged to the outside through the refrigerant outlet 30a. By the action, the ceramic substrate 11 can be cooled.

The above-mentioned hot plate is a device in which only the resistance heating element is provided on the surface of the ceramic substrate, and by this, an object to be heated such as a silicon wafer can be heated to a predetermined temperature. The hot plate of the present invention is an apparatus mainly used for manufacturing semiconductors and inspecting semiconductors, in which only a resistance heating element is provided on a ceramic substrate, but an electrostatic electrode is provided inside the ceramic substrate. When it is provided, it functions as an electrostatic chuck, and when a conductor layer is provided on the surface of the ceramic substrate and when a guard electrode or a ground electrode is provided inside the ceramic substrate, it functions as a wafer prober.

Next, a method of manufacturing a hot plate having a resistance heating element formed on the bottom surface will be described with reference to FIGS.

(1) Manufacturing process of ceramic substrate A slurry is prepared by adding a sintering aid such as yttria or a binder, if necessary, to the above-mentioned nitride ceramic such as aluminum nitride, and then spray drying this slurry. And the like, and the granules are put into a mold or the like to be pressed into a plate shape to prepare a green shaped body. In order to contain carbon in the ceramic substrate, an acrylic resin or the like in which carbon easily remains is usually used as a binder. This acrylic resin is advantageous in the present invention because carbon having low crystallinity is generated by thermal decomposition.

Next, this green body is heated, fired and sintered to produce a ceramic plate-like body. After that, the ceramic substrate 11 is manufactured by processing it into a predetermined shape, but it may have a shape that can be used as it is after firing. By heating and firing while applying pressure, it becomes possible to manufacture the ceramic substrate 11 having no pores. The heating and firing may be carried out at a sintering temperature or higher, but in the case of a nitride ceramic, it is 1000 to 2500 ° C.

Next, lifter pins 16 for carrying a silicon wafer are transferred to the ceramic substrate, if necessary.
A through hole 15 for inserting a through hole, a bottomed hole 14 for embedding a temperature measuring element such as a thermocouple, a recess for embedding a support pin for supporting a silicon wafer, etc. are formed (FIG. 5).
(A)).

(2) Step of printing the conductor paste on the ceramic substrate Using the conductor paste, the conductor pattern is printed on the heating element pattern by a method such as screen printing.
Since it is necessary for the resistance heating element to have a uniform temperature over the entire ceramic substrate, it is preferable to print the resistance heating element in a pattern in which concentric circles and curved lines are combined as shown in FIG. The conductor paste layer is preferably formed such that the resistance heating element 12 after firing has a rectangular cross section.

(3) Firing of Conductor Paste The conductor paste layer printed on the bottom surface of the ceramic substrate 11 is heated and fired to remove the resin and the solvent, the precious metal particles are sintered, and the bottom surface of the ceramic substrate 11 is baked. The resistance heating element 12 is formed (FIG. 5B). The heating and firing temperature is preferably 500 to 1000 ° C. When the above-mentioned metal oxide is added to the conductor paste, the noble metal particles, the metal oxide and the ceramic substrate are sintered and integrated, so that the adhesion between the resistance heating element and the ceramic substrate is improved.

(4) Formation of Metal Cover Layer Next, a metal cover layer 120 is provided on the surface of the resistance heating element 12 (FIG. 5 (c)). The metal coating layer 120 can be formed by electrolytic plating, electroless plating, sputtering, etc. However, in consideration of mass productivity, electroless plating is most suitable.

(5) Attachment of terminals and the like The external terminals 13 for connection to the power source are attached to the ends of the pattern of the resistance heating element 12 by using solder or the like. Further, a temperature measuring element (thermocouple) 18 is inserted into the bottomed hole 14 and sealed with a heat resistant resin such as polyimide or ceramics to form the hot plate 10 (FIG. 5D).

When manufacturing the above hot plate, an electrostatic chuck can be manufactured by providing an electrostatic electrode inside the ceramic substrate, and a chuck top conductor layer is provided on the heating surface so that the inside of the ceramic substrate is A wafer prober can be manufactured by providing a guard electrode and a ground electrode on the substrate.

When the electrodes are provided inside the ceramic substrate, a metal foil or the like may be embedded inside the ceramic substrate. When forming a conductor layer on the surface of a ceramic substrate, a sputtering method or a plating method can be used, and these may be used together.

Next, a method for manufacturing a hot plate having a resistance heating element inside a ceramic substrate will be described with reference to FIGS.

(1) Green Sheet Manufacturing Step First, a powder of nitride ceramic is mixed with a binder, a solvent and the like to prepare a paste, and the paste is used to manufacture a green sheet. Aluminum nitride or the like can be used as the above-mentioned ceramic powder, and if necessary, a sintering aid such as yttria may be added. Further, it is desirable to use an acrylic resin or the like in which carbon easily remains as a binder when manufacturing the green sheet, but amorphous carbon may be added.

The binder is preferably at least one selected from acrylic binders, ethyl cellulose, butyl cellosolve, and polyvinyl alcohol.
Further, the solvent is preferably at least one selected from α-terpineol and glycol.

The paste obtained by mixing these is formed into a sheet by the doctor blade method to obtain a green sheet 5.
Create 0. The thickness of the green sheet 50 is 0.1
5 mm is preferable. Next, on the obtained green sheet,
If necessary, a portion to be a through hole for inserting a support pin for supporting a silicon wafer, a portion to be a through hole 25 for inserting a lifter pin for carrying a silicon wafer, and a temperature measuring element such as a thermocouple. And a portion 280 to be a through hole for connecting the resistance heating element to an external terminal is formed. The above-mentioned processing may be performed after forming a green sheet laminate described below.

(2) Step of printing conductor paste on the green sheet A conductor paste is printed on the green sheet 50 to form the conductor paste layer 220. In addition, a conductor paste is filled in the portion to be the through hole.

Metal particles or conductive ceramic particles are contained in these conductive pastes. Examples of the material of the metal particles include tungsten and molybdenum, and examples of the conductive ceramics include tungsten carbide and molybdenum carbide.

The average particle diameter of the above-mentioned metal particles such as tungsten particles or molybdenum particles is preferably 0.1 to 5 μm. Average particle size is less than 0.1 μm or 5 μm
If it exceeds, it is difficult to print the conductor paste.

Examples of such a conductor paste include, 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. And 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 not printed with the conductor paste or the like produced in the above step (1) is replaced with the green sheet having the paste layer 220 produced in the above step (2). It is laminated on and under 50 (FIG. 6A). At this time, the number of green sheets 50 stacked on the upper side is made larger than the number of green sheets 50 stacked on the lower side, and the formation position of the resistance heating element 22 is eccentric in the direction of the bottom surface. Specifically, the number of stacked upper green sheets 50 is preferably 20 to 50, and the number of stacked lower green sheets 50 is preferably 5 to 20.

(4) Firing Step of Green Sheet Laminated Body The green sheet laminated body is heated and pressed to sinter the green sheet 50 and the conductor paste inside to produce the ceramic substrate 31 (FIG. 6B). ). The heating temperature is
1000-2000 degreeC is preferable and the pressure of pressurization is 10
-20 MPa is preferable. The heating is performed in an inert gas atmosphere. As the inert gas, for example, argon, nitrogen or the like can be used.

A through hole 25 for inserting the lifter pin, a bottomed hole (not shown) for inserting the temperature measuring element, and a blind hole for inserting the external terminal 23 are formed in the obtained ceramic substrate 21. 27 and the like are provided (FIG. 6C). Through hole 2
5, the bottomed hole and the blind hole 27 can be formed by performing blasting processing such as drilling or sandblasting after the surface is polished.

Next, the external terminal 23 is connected to the through hole 28 exposed from the bag hole 27 by using a gold solder or the like (FIG. 6).
(D)). Further, although not shown, the external terminal 23
For example, a socket having a conductive wire is detachably attached. The heating temperature is 90 to 45 in the case of soldering.
0 ° C. is preferred and 900 ° C. for brazing
~ 1100 ° C is preferred. Further, a thermocouple as a temperature measuring element is sealed with a heat resistant resin to form a ceramic heater.

(5) After that, the ceramic substrate 21 having the resistance heating element 12 therein is attached to a cylindrical supporting container, and the lead wire extending from the socket is connected to the power source, whereby the ceramic heater Production is terminated.

Also when manufacturing the above hot plate, an electrostatic chuck can be manufactured by providing an electrostatic electrode inside the ceramic substrate, and a chuck top conductor layer is provided on the heating surface to make the ceramic substrate A wafer prober can be manufactured by providing a guard electrode and a ground electrode inside.

When an electrode is provided inside the ceramic substrate, a conductor paste layer may be formed on the green sheet in a pattern such as an electrostatic electrode or a guard electrode, laminated, and fired. When forming a conductor layer on the surface of the ceramic substrate, the conductor layer may be formed by using a sputtering method or a plating method after manufacturing the ceramic substrate. At this time, the sputtering method and the plating method may be used together.

[0084]

The present invention will be described in more detail below. (Example 1) Production of hot plate (see FIG. 6) (1) 100 parts by weight of aluminum nitride powder (manufactured by Tokuyama Corporation, average particle size 1.1 μm), yttria (average particle size:
0.4 μm) 4 parts by weight, acrylic resin binder (SA-545 series manufactured by Mitsui Chemicals, Inc., acid value 0.5) 10 parts by weight, dispersant 0.5 parts by weight, and alcohol 53 parts by weight consisting of 1-butanol and ethanol. By using the mixed paste of (1) and (2), a doctor blade method was performed to obtain a green sheet having a thickness of 0.47 mm.

(2) Next, this green sheet is heated to 80 ° C.
1.8m in diameter after punching after drying for 5 hours.
m, 3.0 mm, and 5.0 mm through holes were formed, and a portion to be a through hole for connecting to an external terminal was provided.

(3) 100 parts by weight of tungsten carbide particles having an average particle diameter of 1 μm and an acrylic binder of 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. A conductor paste B was prepared by mixing 100 parts by weight of tungsten particles having an average particle diameter of 3 μm, 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. This conductor paste A was printed on a green sheet by screen printing to form a conductor paste layer for a resistance heating element. The printing pattern was a concentric circular pattern.

Further, the conductor paste B was filled into the through holes for through holes for connecting the external terminals. 34 green sheets 50 on which the tungsten paste is not printed are further laminated on the upper side (heating surface) and 13 sheets are laminated on the lower side of the green sheet 50 after the above-mentioned treatment.
A laminated body was formed by pressure bonding at 30 ° C. and a pressure of 80 kg / cm ² (FIG. 6A).

(4) Next, the obtained laminated body was degreased in nitrogen gas at 600 ° C. for 10 hours, at 1890 ° C. and a pressure of 15 °.
Hot pressing was performed at 0 kg / cm ² for 3 hours to obtain an aluminum nitride plate-shaped body having a thickness of 3 mm. This was cut into a disk shape of 230 mm to obtain a plate-shaped body (ceramic substrate 21) made of aluminum nitride having a resistance heating element 22 having a thickness of 6 μm and a width of 10 mm therein (FIG. 6B). When the crystallinity of carbon contained in the ceramic substrate 21 was examined by laser Raman spectrum, it was 1580 cm ⁻¹ and 1
A peak was observed at 355 cm ^-1 . It can be seen that the peak at 1355 cm ^{−1 is} a peak showing amorphousness and the crystallinity is low.

(5) Next, the plate-like body obtained in (4) is
After polishing with a diamond grindstone, place a mask and
A bottomed hole (diameter: 1.2 mm, depth: 2.0 mm) for a thermocouple and a through hole for inserting a lifter pin were provided on the surface by blasting with C or the like (Fig. 6 (c)). .

(6) Further, the portion where the through hole is formed is cut out to form a bag hole 27 (FIG. 7 (c)),
A gold solder made of Ni-Au is used for the bag hole 27,
An external terminal 23 made of Kovar was connected by heating and reflowing at 0 ° C. (FIG. 7 (d)). The connection of the external terminals is preferably a structure in which the tungsten support supports at three points.
This is because connection reliability can be secured.

(7) Next, a plurality of thermocouples for temperature control were embedded in a bottomed hole using a resin such as polyimide to complete the manufacture of the hot plate.

Example 2 Production of Hot Plate (See FIG. 5) (1) 100 parts by weight of aluminum nitride powder (produced by Tokuyama Corporation, average particle size 1.1 μm), yttrium oxide (Y ₂ O)
₃ : 4 parts by weight of yttria, average particle size of 0.4 μm, 8 parts by weight of acrylic resin binder (KC-600 series, Kyoeisha Co., Ltd., acid number 17) and alcohol were spray-dried to give a granular form. A powder was made.

(2) Next, the granular powder was put into a mold and molded into a flat plate to obtain a green molded body (green).

(3) The green body after the processing is hot pressed at a temperature of 1800 ° C. and a pressure of 20 MPa,
An aluminum nitride sintered body having a thickness of 3 mm was obtained. next,
A disk body having a diameter of 310 mm was cut out from this plate body to obtain a ceramic plate body (ceramic substrate 11) (FIG. 5A). Next, this plate-like body is subjected to drilling, a through hole 15 into which a lifter pin 16 for carrying a semiconductor wafer is inserted, and a bottomed hole (diameter: to be filled with a thermocouple).
1.1 mm, depth: 2 mm) 14 was formed.

(4) On the bottom surface of the sintered body obtained in (3) above,
The conductor paste was printed by screen printing. The print pattern was a combination of the concentric circle shape and the bent line shape as shown in FIG. As the conductor paste, Solbest PS603D manufactured by Tokuriki Kagaku Kenkyusho, which is used for forming through holes of printed wiring boards, was used.

This conductor paste is a silver-lead paste, and based on 100 parts by weight of silver, lead oxide (5% by weight), zinc oxide (55% by weight), silica (10% by weight), and boron oxide (25% by weight). % By weight) and 7.5% by weight of a metal oxide composed of alumina (5% by weight). Also,
The silver particles had an average particle size of 4.5 μm and were flaky.

(5) Next, the sintered body on which the conductor paste is printed is heated and fired at 780 ° C. to obtain silver in the conductor paste.
Lead was sintered and baked on the sintered body to form a resistance heating element 12 (FIG. 5B). Silver resistance heating element 12
Has a thickness of 5 μm and a width of 2.4 mm near its end,
The sheet resistivity was 7.7 mΩ / □.

(6) Next, 80 g / l of nickel sulfate, 24 g / l of sodium hypophosphite, and 12 g of sodium acetate.
(4) in an electroless nickel plating bath consisting of an aqueous solution containing 1 g / l, boric acid 8 g / l, and ammonium chloride 6 g / l.
The sintered body prepared in 1. was dipped to deposit a metal coating layer 120 (nickel layer) having a thickness of 1 μm on the surface of the silver resistance heating element 12 (FIG. 5C).

(7) A silver-lead solder paste (manufactured by Tanaka Kikinzoku Co., Ltd.) was printed by screen printing on the end portion for ensuring connection with the power supply to form a solder layer. Then, the external terminal 13 having a T-shaped tip is placed on the solder layer.
Reflowing was performed by heating at 20 ° C., and the external terminal 17 was attached to the end of the resistance heating element 12 via the solder 170. (8) Insert a thermocouple for temperature control into the bottomed hole 13,
Filled with polyimide resin, cured at 190 ℃ for 2 hours,
Hot plate 1 having resistance heating element 12 on bottom surface 11b
I got 0.

(Examples 3 to 4) Production of hot plate Acrylic resin binder (KC-60 manufactured by Kyoeisha Co., Ltd.)
0 series, acid value 17) in an amount of 4 parts by weight (Example 3),
A hot plate was produced in the same manner as in Example 2 except that the amount was 20 parts by weight (Example 4).

(Comparative Example 1) Similar to Example 1, but degreasing was performed at 600 ° C. for 24 hours to reduce the carbon content to about 100 ppm. (Comparative Example 2) Similar to Example 1, but crystalline graphite was added. The amount added in the sintered body was 800 ppm. When the crystallinity of carbon was examined by laser Raman spectrum, a peak was observed at 1580 cm ^-1 . Therefore, it can be seen that this carbon has high crystallinity.

The carbon amount, brightness, and the hot plate according to Examples 1 to 4 and Comparative Examples 1 and 2 thus manufactured were
The transmittance and volume resistivity were examined by the following methods. In addition, the temperature of the heating surface of the ceramic substrate when the temperature was raised to 300 ° C was measured by a thermoviewer (JTC-6100 manufactured by JEOL Ltd.).
Then, the temperature-measuring silicon wafer to which the thermocouple was adhered was placed on the heating surface, and the temperature of the silicon wafer was measured. The measurement results of carbon content, brightness, etc. are shown in Table 1 below.
In addition, regarding the results measured with a thermoviewer or thermocouple, the results of comparing the temperature difference between the highest temperature and the lowest temperature are shown in Table 1 below. Furthermore, the transmittance of each wavelength of the sintered body (thickness 0.5 mm) obtained in Example 1 is shown in FIG. 7, and each of the sintered bodies (thickness 0.5 mm) obtained in Comparative Example 1 is shown. The wavelength transmittance is shown in FIG.

[0103]Evaluation methods (1) Measurement of carbon content Aluminum nitride plates manufactured in the above-mentioned examples and comparative examples
Generated by crushing the powder and heating it at 500-800 ℃
CO_X It was measured by collecting the gas.

(2) Measurement of light transmittance From the ceramic substrates obtained in Examples and Comparative Examples,
Cut out a sintered body with a thickness of 5 mm, 240-2670n
It was installed in a self-recording spectrophotometer (Model U-4000 manufactured by Hitachi, Ltd.) capable of measuring the visible light transmittance of m, and the light transmittance (T / Tw) was measured.

(3) Measurement of volume resistivity By cutting the sintered body, it is cut into a shape with a diameter of 10 mm and a thickness of 3 mm to form three terminals (main electrode, counter electrode, guard electrode), and DC voltage is applied. After reading the current (I) flowing in the digital electrometer after charging for 1 minute, the resistance (R) of the sample is obtained, and the volume resistivity (ρ) is calculated from the resistance (R) and the size of the sample as follows. It was calculated by the formula (1). The temperature in this case is 300 ° C.

[0106]

[Equation 1]

In the above calculation formula (1), t is the thickness (mm) of the sample. Further, S is given by the following calculation formulas (2) and (3).

[0108]

[Equation 2]

[0109]

[Equation 3]

In the above equations (2) and (3), r ₁ is the radius of the main electrode, r ₂ is the inner diameter (radius) of the guard electrode, r ₃ is the outer diameter (radius) of the guard electrode, and D ₁ Is the diameter of the main electrode, D ₂ is the inner diameter (diameter) of the guard electrode, and D ₃ is the outer diameter (diameter) of the guard electrode. In this embodiment, 2r ₁ = D ₁ = 1.45 cm, 2r ₂ = D ₂ = 1.
It is 60 cm and 2r ₃ = D ₃ = 2.00 cm.

[0111]

[Table 1]

As is clear from the graphs shown in FIGS. 7 and 8, the sintered body of Example 1 has almost no absorption of wavelengths in the infrared region, whereas the sintered body of Comparative Example 1 has Absorption of wavelengths in the infrared region is as high as about 20%. In addition, as is clear from Table 1 above, infrared rays (2500
By setting the transmittance of (nm) to 10% or less, the temperature of the heating surface can be accurately measured by a thermoviewer.

[0113]

As described above, in the hot plate of the present invention, since the infrared transmittance of the ceramic substrate is as low as 10% or less, the temperature of the heating surface can be accurately measured by the thermoviewer. Further, the brightness is N4 or less, which is sufficiently blackened, and high radiant heat can be obtained.

[Brief description of drawings]

FIG. 1 is a bottom view schematically showing an example of a hot plate of the present invention.

FIG. 2 is a partially enlarged cross-sectional view schematically showing a part of the hot plate shown in FIG.

FIG. 3 is a partially enlarged sectional view schematically showing another example of the hot plate of the present invention.

FIG. 4 is a sectional view schematically showing a support container into which a hot plate is fitted.

5 (a) to (d) are cross-sectional views schematically showing a part of the manufacturing process of the hot plate of the present invention.

6A to 6D are cross-sectional views schematically showing a part of the manufacturing process of the hot plate of the present invention.

FIG. 7 is a chart showing the absorptance for each wavelength of the ceramic substrate obtained in Example 1.

FIG. 8 is a chart showing the absorptance for each wavelength of the ceramic substrate obtained in Comparative Example 1.

[Explanation of symbols]

10 hot plates 11, 21 Ceramic substrate 11a heating surface 11b, 12b bottom 12 (12a to 12d), 22 resistance heating element 13 edge 14 Bottomed hole 15 through holes 16 lifter pins 17 External terminal 18 Temperature measuring element 19 Silicon wafer 23 External terminal 24 brazing material 27 bag holes 28 through holes 30 Support container 32 guide tube 35 Insulation 37 Holding bracket 38 Volts 39 Refrigerant introduction pipe

Continued front page    F term (reference) 3K034 AA03 AA10 AA16 AA21 AA22                       AA34 BA02 BA15 BA17 BB06                       BB14 BC04 BC12 BC17 BC27                       CA03 CA17 CA24 DA04 EA07                       FA24 JA04 JA10                 3K092 PP20 QA05 QB09 QB13 QB32                       QB44 QB45 QB47 QB63 QB75                       QC07 QC34 QC42 QC43 QC52                       QC53 RF11 RF17 RF22 UA05                       VV16 VV22                 4G030 AA12 AA51 BA12

Claims (3)

[Claims] 1. A hot plate in which a conductor layer is formed on the surface or inside of a ceramic substrate, wherein the ceramic substrate has a transmittance of an infrared wavelength of 0 or 10% or less. . 2. The ceramic substrate according to JIS Z 87.
The hot plate according to claim 1, wherein the brightness based on 21 is N4 or less. 3. The hot plate according to claim 1, wherein the infrared ray has a wavelength of 2500 nm.