JP2003208966A - Ceramic substrate and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic substrate, which has excellent soaking nature and thermal shock properties, and when it is used as a static chuck, which has large chuck force. <P>SOLUTION: With respect to the ceramic substrate in which a conductor layer is formed in the inside of the ceramic substrate, the section of the end part of the above conductor layer is cusp-like. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic substrate mainly used in the semiconductor industry, and is particularly suitable for hot plates, electrostatic chucks, wafer probers, etc., and has thermal shock resistance, thermal uniformity, and chucking force. The present invention relates to a ceramic substrate excellent in the above.

[0002]

2. Description of the Related Art Semiconductors are extremely important products required in various industries.
It is manufactured by slicing a silicon single crystal into a predetermined thickness to manufacture a silicon wafer, and then forming a plurality of integrated circuits and the like on the silicon wafer.

In the process of manufacturing this semiconductor chip,
A silicon wafer placed on the electrostatic chuck is subjected to various treatments such as etching and CVD to form conductor circuits, elements and the like. At that time, since a corrosive gas is used as a deposition gas, an etching gas, etc., it is necessary to protect the electrostatic electrode layer from corrosion by these gases, and it is also necessary to induce an adsorption force. Therefore, the electrostatic electrode layer is usually covered with a ceramic dielectric film or the like. As this ceramic substrate, Japanese Patent Publication No. 27
No. 98570, Japanese Patent Publication No. 2513995, Japanese Patent Laid-Open No. 11-74064 and the like describe an electrostatic chuck with a heater in which a metal paste such as tungsten (W) is printed and laminated on a green sheet.

[0004]

However, in a ceramic substrate manufactured by such a method, when a thermal shock is applied, a crack is generated from an end portion of a conductor layer such as a resistance heating element, or the heating element is deformed. As a result, problems such as the generation of high temperature regions occurred. Further, the chucking force also varies, and a sufficient suction force cannot be obtained. Further, regarding the internal electrodes and the resistance heating element, a leakage current at a high temperature between the electrodes and the resistance heating element poses a problem.

[0005]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that the end portions of the cross sections of the conductor layers forming the electrostatic electrode, the RF electrode and the resistance heating element are sharpened. The present invention has been newly found out that these problems can be solved by making the head shape, and the present invention has been completed.

That is, the present invention relates to a ceramic substrate in which a conductor layer is formed inside the ceramic substrate,
The cross section of the end portion of the conductor layer is a pointed shape, which is a ceramic substrate.

In the ceramic substrate of the present invention, when the conductor layer is a resistance heating element, it functions as a hot plate, and when the conductor layer is an electrostatic electrode, it functions as an electrostatic chuck. The ceramic substrate of the present invention,
It is desirable to use at temperatures above 150 ° C,
Most preferably it is used at temperatures above 0 ° C.

In the ceramic substrate, the conductor layer preferably has a pointed portion having a width of 0.1 to 200 μm, and more preferably has a pointed portion having a width of 5 to 100 μm. Further, when manufacturing the above-mentioned ceramic substrate, it is preferable to adopt a method of printing a conductor layer on a ceramic green sheet, pressurizing and integrating with another green sheet, and then sintering the ceramic.

When the conductor layer embedded in the ceramic substrate used in the present invention is an electrode for inducing the chucking force of the electrostatic chuck, that is, an electrostatic electrode, the end portion of the electrode is pointed. It is considered that the electric field is concentrated along this end and a large chucking force is induced.

An analysis of the reason why cracking occurs due to thermal shock shows that the conductor layer manufactured by the conventional printing method has a substantially rectangular cross section, and the wafer processing surface (semiconductor wafer is heated and held). , The surface to be adsorbed) has a surface perpendicular to. Further, the coefficient of thermal expansion of the conductor layer is different from that of the ceramic constituting the ceramic substrate. Therefore, when the ceramic substrate is heated or cooled, a force for separating the surface of the conductor layer perpendicular to the wafer processing surface from the ceramic is applied, and this force is likely to cause cracks. However, in the ceramic substrate of the present invention, since the conductor layer does not have a surface perpendicular to the wafer processing surface, cracks are less likely to occur.

Further, it is considered that the high temperature region is generated along the resistance heating element because heat is likely to be accumulated at the intersection of the surface perpendicular to the processing surface of the wafer and the horizontal surface of the resistance heating element. The reason why such a heat storage phenomenon occurs is not clear, but the heat is radiated and propagated from both the surface of the resistance heating element, which is perpendicular to the processing surface of the wafer, and the horizontal surface of the resistance heating element, and these heat intersect at the intersection line. It is presumed that it is because it does. However, in the ceramic substrate of the present invention, since there is no surface perpendicular to the wafer processing surface, such a heat storage phenomenon does not occur, and the thermal uniformity on the wafer processing surface is excellent.
In addition, electrodes (a wafer prober guard electrode, a ground electrode, an electrostatic chuck electrode, R
In the case of having a conductor layer such as an F electrode) or a resistance heating element, if there are planes perpendicular to the wafer processing surface of the conductor layer, these planes face each other, and a leak current at high temperature easily occurs. . In the present invention, the conductor layer has a pointed end cross-section, and the surfaces do not face each other, so that a leak current at a high temperature is unlikely to occur. The ceramic substrate of the present invention is 15
It is used in a temperature range of 0 ° C or higher, preferably 200 ° C or higher.

The conductor layer of the present invention may be an electrostatic electrode, a resistance heating element, an RF electrode, a guard electrode used in a wafer prober, or a ground electrode.

The conductor layer preferably has a pointed portion with a width of 0.1 to 200 μm. This is because if the width of the pointed portion exceeds 200 μm, the resistance value varies, and if it is less than 0.1 μm, the effect of preventing cracks and the like does not occur. The width of the pointed portion is particularly preferably 5 to 100 μm. Further, the radius of curvature of the pointed portion is optimally 0.5 to 500 μm.

In the ceramic substrate of the present invention, the maximum pore diameter is preferably 50 μm or less, and the porosity is preferably 5% or less. In addition, the ceramic substrate,
If there are no pores or if there are pores, the maximum pore size is preferably 50 μm or less.

When there are no pores, the withstand voltage at a high temperature is particularly high, and conversely, when there are pores, the fracture toughness value is high. Or either the design for this is the vary required characteristics. The reason why the fracture toughness value increases due to the existence of pores is not clear, but it is presumed that the crack propagation is stopped by the pores.

In the present invention, it is desirable that the maximum pore diameter is 50 μm or less, because if the pore diameter exceeds 50 μm, it becomes difficult to secure the withstand voltage characteristics at high temperature, especially at 200 ° C. or higher. is there. The maximum pore size is 10
μm or less is desirable. This is because the amount of warpage at 200 ° C. or higher becomes small.

The porosity and the pore size of the maximum pores are adjusted by the pressurizing time during sintering, pressure, temperature, and additives such as SiC and BN. Since SiC and BN hinder sintering, it is possible to introduce pores.

When measuring the pore diameter of the maximum pores, five samples are prepared, and the surfaces thereof are mirror-polished to 2000 to 50.
The surface is photographed at 10 sites with an electron microscope at a magnification of 00 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. The sinter is crushed, the crushed product is put in an organic solvent or mercury, the volume is measured, the true specific gravity is calculated from the weight and volume of the crushed product, and the porosity is calculated from the true specific gravity and the apparent specific gravity. .

The diameter of the ceramic substrate of the present invention is 200 m.
m or more is desirable. Particularly, it is desirable that it is 12 inches (300 mm) or more. This is because it will become the mainstream of next-generation semiconductor wafers.

The ceramic substrate of the present invention has a thickness of 50 m.
m or less is desirable, and 25 mm or less is particularly desirable. When the thickness of the ceramic substrate exceeds 25 mm, the heat capacity of the ceramic substrate may be too large. Especially, when the temperature control means is provided for heating and cooling, the temperature followability deteriorates due to the heat capacity. This is because it may happen.
The optimum thickness of the ceramic substrate is 5 mm or less. The thickness of the ceramic substrate is preferably 1 mm or more.

The ceramic material forming the ceramic substrate of the present invention is not particularly limited, and examples thereof include nitride ceramics, carbide ceramics and oxide ceramics.

Examples of the above-mentioned nitride ceramics include metal nitride ceramics such as aluminum nitride, silicon nitride and boron nitride. Examples of the carbide ceramics include metal carbide ceramics such as silicon carbide, zirconium carbide, 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.

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

The ceramic substrate is 0.1 to 5% by weight.
It is desirable to contain the above oxygen. In this case, for example, in the case of the nitride ceramic, the sintering is likely to proceed, and even when the pores are included, the pores become independent pores and the withstand voltage is improved. This is because if it is less than 0.1% by weight, the withstand voltage cannot be secured, and conversely, if it exceeds 5% by weight, the withstand voltage is also lowered due to the deterioration of the high temperature withstand voltage characteristic of the oxide. Further, if the amount of oxygen exceeds 5% by weight, the thermal conductivity decreases and the temperature rising / falling characteristics deteriorate.

For example, in order to make the above-mentioned nitride ceramic contain oxygen, the nitride ceramic is usually fired in an oxidizing atmosphere, or the raw material powder of the nitride ceramic is mixed with a metal oxide and fired. I do. In the case of oxide ceramics, other oxides are mixed to form a composite oxide. Examples of the metal oxide 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 ) and the like. The content of these metal oxides is preferably 0.1 to 20% by weight.

In the present invention, 5 to 50 are contained in the ceramic substrate.
It is desirable to contain 00 ppm of carbon.
By including carbon, the ceramic substrate can be blackened, and radiant heat can be sufficiently utilized when it is used as a heater. The carbon may be amorphous or crystalline. When amorphous carbon is used, it is possible to prevent a decrease in volume resistivity at high temperatures, and when crystalline carbon is used, it is possible to prevent a decrease in thermal conductivity at high temperatures. Because. Therefore, depending on the application, both crystalline carbon and amorphous carbon may be used together. The carbon content is 50 to 2
000 ppm is more preferable.

When carbon is contained in the ceramic substrate, it is desirable to contain carbon so that the lightness thereof is N4 or less as a value based on the regulation of JIS Z8721. Radiant heat has a brightness of this level,
This is because it has excellent concealing properties.

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. The actual brightness is measured from N0 to N1.
It is performed by comparing with the color chart corresponding to 0. Decimal point 1 in this case
The place is 0 or 5.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION The ceramic substrate of the present invention is a ceramic substrate used in an apparatus for manufacturing a semiconductor and inspecting a semiconductor. Specific examples of the apparatus include an electrostatic chuck and a hot plate ( Ceramic heaters), wafer probers, etc.

When the conductor formed inside the ceramic substrate is a resistance heating element, it can be used as a ceramic heater (hot plate). Figure 1
FIG. 2 is a plan view schematically showing an example of a ceramic heater that is an embodiment of the ceramic substrate of the present invention.
[Fig. 2] is a partially enlarged cross-sectional view showing a part of the ceramic heater shown in Fig. 1.

The ceramic substrate 11 is formed in a disc shape, and a resistance heating element 12 as a temperature control means is formed in a concentric pattern inside the ceramic substrate 11. In addition, these resistance heating elements 12 are connected so that double concentric circles close to each other form a single line, and external terminals 13 serving as input / output terminals are provided at both ends of the circuit. It is connected through a through hole 19. Further, as shown in FIG. 2, the resistance heating element 12 has a pointed cross-section at both ends thereof, so that the ceramic substrate 11 is less likely to be cracked due to thermal shock and the like. The heat accumulation phenomenon does not occur at the end portion 12 and the temperature distribution does not occur on the wafer processing surface, resulting in a uniform temperature.

Further, as shown in FIG. 2, a through hole 15 is provided in the ceramic substrate 11, the support pin 26 is inserted through the through hole 15, and the silicon wafer 9 is held. By moving the support pin 26 up and down,
In a state where the silicon wafer 9 is received from the carrier, the silicon wafer 9 is placed on the wafer processing surface 11a of the ceramic substrate 11 and heated, or the silicon wafer 9 is separated from the wafer processing surface 11a at a constant interval. It can be supported and heated. In addition, the ceramic substrate 11
A bottomed hole 14 for inserting a temperature measuring element such as a thermocouple is provided in the bottom surface 11a of the. And the resistance heating element 1
When 2 is energized, the ceramic substrate 11 is heated, so that an object to be heated such as a silicon wafer can be uniformly heated.

In the case of a ceramic heater, by providing a resistance heating element having a pointed cross section inside the ceramic substrate, the resistance heating element has the above-described effects of the present invention. In the case of an electrostatic chuck or a wafer prober described later, the resistance heating element may be provided on the bottom surface of the ceramic substrate. In this case, by making the cross-sections of the ends of the electrostatic electrode, the guard electrode, the ground electrode, etc., pointed, these electrodes have the above-described effects of the present invention.

When the resistance heating element is provided inside the ceramic substrate, a support container in which the ceramic substrate is fitted may be provided with a blowing port for a cooling medium such as air as a cooling means. 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.

The resistance heating element is preferably made of a metal such as a noble metal (gold, silver, platinum, palladium), lead, tungsten, molybdenum, nickel, or a conductive ceramic such as a carbide of tungsten or molybdenum. . It is possible to increase the resistance value, it is possible to increase the thickness itself for the purpose of preventing disconnection, etc.,
This is because it is difficult to oxidize and the thermal conductivity does not easily decrease. These may be used alone or in combination of two or more.

Further, since the resistance heating element is required to make the temperature of the entire ceramic substrate uniform, a concentric pattern as shown in FIG. 1 or a combination of a concentric pattern and a bent line pattern is used. Those are preferable.
The thickness of the resistance heating element is preferably 1 to 50 μm,
The width is preferably 5 to 20 mm. Further, it is desirable that this resistance heating element has a pointed portion having a width of 0.1 to 200 μm.

The resistance value can be changed by changing the thickness or width of the resistance heating element, but the above range is most practical. The resistance value of the resistance heating element is
It becomes thinner and becomes thinner as it becomes thinner.

When the resistance heating element is provided inside, the distance between the heating surface and the resistance heating element becomes short, and the uniformity of the temperature on the surface deteriorates. Therefore, it is necessary to widen the width of the resistance heating element itself. Further, since the resistance heating element is provided inside the ceramic substrate, it is not necessary to consider the adhesiveness with the ceramic substrate.

The resistance heating element may have any of a square shape, an elliptical shape, a spindle shape, and a semi-cylindrical cross section, but it is preferable that the resistance heating element is flat and the cross section of the end portion is preferably pointed. This is because the flat surface is more likely to radiate heat toward the heating surface, so that the amount of heat transfer to the heating surface can be increased and the temperature distribution on the heating surface is less likely to occur. The resistance heating element may have a spiral shape. When the resistance heating element is formed inside the ceramic substrate, it is desirable to form the resistance heating element in an area up to 60% in the thickness direction from the bottom surface. Eliminate the temperature distribution on the heating surface,
This is because the semiconductor wafer can be heated uniformly. An object to be heated such as a semiconductor wafer may be placed directly on the heating surface and heated. Further, the object to be heated can be held and heated while being separated from the heating surface by about 50 to 200 μm.

In order to form the resistance heating element on the bottom surface or inside of the ceramic substrate for a semiconductor device of the present invention, it is preferable to use a conductive paste made of metal or conductive ceramic. That is, when the resistance heating element is formed on the bottom surface of the ceramic substrate, the resistance heating element is usually formed by firing to form the ceramic substrate, and then forming the conductor paste layer on the surface and firing. To form. on the other hand,
When the resistance heating element 12 is formed inside the ceramic substrate 11 as shown in FIGS. 1 and 2, after the conductive paste layer is formed on a green sheet, it is pressed with another green sheet while being heated and integrated. To produce a green sheet laminate. At this time, by heating to a temperature at which the dried conductor paste is easily deformed to some extent, a conductor paste layer having a pointed end can be formed. After that, by firing the laminated body, it is possible to produce a resistance heating element having a pointed end in cross section inside the ceramic substrate.

The conductor paste is not particularly limited, but it is preferable that the conductor paste contains metal particles or conductive ceramic particles in order to ensure conductivity, and contains a resin, a solvent, a thickener and the like.

Examples of the material of the above-mentioned metal particles and conductive ceramic particles include those mentioned above. The particle size of these metal particles or conductive ceramic particles is 0.1-10.
0 μm is preferable. This is because if it is less than 0.1 μm and too fine, it is easily oxidized, while if it exceeds 100 μm, it becomes difficult to sinter and the resistance value increases.

Even if the shape of the metal particles is spherical,
It may be flaky. When these metal particles are used, they may be a mixture of the above-mentioned spherical material and the above-mentioned scaly material.

When the metal particles are scaly particles or a mixture of spherical particles and scaly particles, it becomes easier to hold the metal oxide between the metal particles, and the resistance heating element adheres to the ceramic substrate. Is assured and the resistance value can be increased, which is advantageous.

Examples of the resin used for the conductor paste include acrylic resin, epoxy resin, phenol resin and the like. Examples of the solvent include isopropyl alcohol and the like. Examples of the thickener include cellulose and the like.

When forming the conductor paste for the resistance heating element on the surface of the ceramic substrate, a metal oxide is added to the conductor paste in addition to the metal particles, and the metal particles and the metal oxide are burned. It is preferable that they are bound. By thus sintering the metal oxide together with the metal particles, the ceramic substrate and the metal particles can be brought into closer contact with each other.

Although the reason why the adhesion with the ceramic substrate is improved by mixing the above metal oxides is not clear, the surface of the metal particles or the surface of the ceramic substrate made of non-oxide is slightly different. It is considered that the oxide film is formed by being oxidized, and the oxide films are sintered and integrated with each other through the metal oxide, and the metal particles and the ceramic adhere to each other. In addition, when the ceramic forming the ceramic substrate is an oxide, the surface is naturally made of an oxide, so that a conductor layer having excellent adhesion is formed.

Examples of the metal oxide include, for example, oxidation.
Lead, zinc oxide, silica, boron oxide (B ₂ O₃ ), Al
Selected from the group consisting of Mina, Yttria and Titania
At least one is preferable. These oxides have resistance
Without increasing the resistance value of the heating element,
Because it can improve the adhesion to the Mick substrate.
It

The above lead oxide, zinc oxide, silica, boron oxide (B ₂ O ₃ ), alumina, yttria, and titania are in a weight ratio when the total amount of metal oxides is 100 parts by weight. 1-10, silica 1-30, boron oxide 5-50, zinc oxide 20-70, alumina 1
-10, yttria is 1-50, and titania is 1-50, and it is preferable that the total is adjusted within a range not exceeding 100 parts by weight. By adjusting the amount of these oxides within these ranges, the adhesion to the ceramic substrate can be particularly improved.

The amount of the above metal oxide added to the metal particles is preferably 0.1% by weight or more and less than 10% by weight. Further, the area resistivity when the resistance heating element is formed using the conductor paste having such a configuration is preferably 1 to 45 mΩ / □.

If the sheet resistivity exceeds 45 mΩ / □, the amount of heat generated becomes too large with respect to the amount of applied voltage, and it is difficult to control the amount of heat generated by the ceramic substrate for semiconductor device having a resistance heating element on the surface. Because. In addition, when the addition amount of the metal oxide is 10% by weight or more, the area resistivity is 50%.
Since it exceeds mΩ / □, the amount of heat generated becomes too large, which makes temperature control difficult and reduces the uniformity of temperature distribution.

When the resistance heating element is formed on the surface of the ceramic substrate, a metal coating layer is preferably formed on the surface portion of the resistance heating element. This is to prevent the internal metal sintered body from being oxidized and changing its resistance value.
The thickness of the metal coating layer formed is preferably 0.1 to 10 μm.

The metal used for forming the metal coating layer is not particularly limited as long as it is a non-oxidizing metal.
Specific examples include gold, silver, palladium, platinum, nickel and the like. These may be used alone,
You may use 2 or more types together. Of these, nickel is preferred. When the resistance heating element is formed inside the ceramic substrate, the surface of the resistance heating element is not oxidized, and thus the coating is unnecessary.

When the conductor formed inside the ceramic substrate is an electrostatic electrode layer, the ceramic substrate can be used as an electrostatic chuck. In this case, the RF electrode and the resistance heating element are below the electrostatic electrode,
It may be formed as a conductor in the ceramic substrate. FIG. 3 is a vertical sectional view schematically showing an embodiment of the electrostatic chuck according to the present invention, and FIG. 4 is a sectional view taken along the line AA of the electrostatic chuck shown in FIG.

In this electrostatic chuck 101, an electrostatic electrode layer composed of a chuck positive electrode electrostatic layer 2 and a chuck negative electrode electrostatic layer 3 is embedded inside a disk-shaped ceramic substrate 1, and this electrostatic electrode layer is embedded. A thin ceramic layer 4 (hereinafter referred to as a ceramic dielectric film) is formed on the electrode layer. The silicon wafer 9 is placed on the electrostatic chuck 101 and is grounded.

As shown in FIG. 4, the chuck positive electrode electrostatic layer 2 comprises a semi-circular arc shaped portion 2a and a comb tooth portion 2b, and the chuck negative electrode electrostatic layer 3 also has a semi-circular arc shaped portion 3a and a comb tooth portion. Part 3b
The chuck positive electrode electrostatic layer 2 and the chuck negative electrode electrostatic layer 3 are arranged so as to face each other so as to intersect the comb teeth 2b and 3b. The negative electrode electrostatic layer 3 has a DC power source +
The negative side and the negative side are connected to each other, and the DC voltage V ₂ is applied. Then, as shown in FIG. 3, the resistance heating element 5, the chuck positive electrode electrostatic layer 2, and the chuck negative electrode electrostatic layer 3 are used.
Forming semi-circular portions 2a, 3a and comb tooth portions 2b, 3
The cross section at the end with b is pointed.

Inside the ceramic substrate 1, a resistance heating element 5 having a concentric circular shape in plan view as shown in FIG. 1 is provided in order to control the temperature of the silicon wafer 9, and the resistance heating element 5 is provided. External terminals are connected to both ends of
It is fixed and the voltage V ₁ is applied. Although not shown in FIGS. 3 and 4, on the ceramic substrate 1, as shown in FIGS. 1 and 2, a bottomed hole for inserting a temperature measuring element and a support for vertically moving the silicon wafer 9 are supported. A through hole for inserting a pin (not shown) is formed. The resistance heating element may be formed on the bottom surface of the ceramic substrate.

When the electrostatic chuck 101 is made to function, a DC voltage V ₂ is applied to the chuck positive electrode electrostatic layer 2 and the chuck negative electrode electrostatic layer 3. As a result, the silicon wafer 9 is adsorbed and fixed to these electrodes via the ceramic dielectric film 4 by the electrostatic action of the chuck positive electrode electrostatic layer 2 and the chuck negative electrode electrostatic layer 3. . After fixing the silicon wafer 9 on the electrostatic chuck 101 in this manner, the silicon wafer 9 is subjected to various processes such as CVD. In the electrostatic chuck 101 according to the present invention,
Since the cross sections of the chuck positive and negative bending electrostatic layers 2 and 3 are pointed, the electric field is concentrated along the ends, and a large chucking force is attracted. In addition, the chuck positive and negative curved electrostatic layers 2, 3
Since the end portion of the resistance heating element 5 has a pointed cross section, cracks are less likely to occur, and a heat storage phenomenon does not occur at the end portion of the resistance heating element 5.

In the electrostatic chuck 101, the ceramic dielectric film 4 is made of a nitride ceramic containing oxygen, has a porosity of 5% or less, and has a maximum pore diameter of 5%.
It is preferably 0 μm or less. Moreover, it is desirable that the pores in the ceramic dielectric film 4 are formed of pores independent of each other. In the ceramic dielectric film 4 having such a configuration, a gas or the like which lowers the withstand voltage penetrates the ceramic dielectric film to corrode the electrostatic electrode,
The withstand voltage of the ceramic dielectric film does not decrease even at high temperatures.

As the temperature control means, in addition to the resistance heating element 12, a Peltier element (see FIG. 7) can be cited. When a Peltier element is used as the temperature control means, both heat generation and cooling can be performed by changing the direction of current flow, which is advantageous. As shown in FIG. 7, the Peltier element 8 has p-type and n-type thermoelectric elements 81 connected in series,
It is formed by bonding this to a ceramic plate 82 or the like. As the Peltier device, for example, silicon
Examples include germanium-based, bismuth-antimony-based, lead-tellurium-based materials, and the like.

The electrostatic chuck of the present invention is, for example, as shown in FIG.
It has a structure as shown in FIG. The material of the ceramic substrate and the like have already been described, but in the following, other members constituting the above-mentioned electrostatic chuck and other embodiments of the electrostatic chuck of the present invention will be described.
It will be explained in detail in order.

The material of the ceramic dielectric film forming the electrostatic chuck of the present invention is not particularly limited, and examples thereof include oxide ceramics, nitride ceramics, oxide ceramics, etc. Among these, nitride ceramics are preferable. preferable.
Examples of the above-mentioned nitride ceramics include those similar to the above-mentioned ceramic substrate. The nitride ceramic preferably contains oxygen. In this case, the nitride ceramic is more likely to be sintered, and even when it contains pores, the pores become independent pores and the withstand voltage is improved.

In order to make the above-mentioned nitride ceramic contain oxygen, usually, a raw material powder of the nitride ceramic is mixed with a metal oxide and fired. Examples of the metal oxide include alumina (Al ₂ O ₃ ) and silicon oxide (SiO ₂ ). The addition amount of these metal oxides is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the nitride ceramic.

The thickness of the ceramic dielectric film is 50 to 50.
By setting the thickness to 00 μm, a sufficient withstand voltage can be secured without reducing the chucking force. If the thickness of the ceramic dielectric film is less than 50 μm, a sufficient withstand voltage cannot be obtained because the film thickness is too thin, and when the silicon wafer is placed and adsorbed, dielectric breakdown of the ceramic dielectric film occurs. In some cases, the ceramic dielectric film has a thickness of 50
If it exceeds 00 μm, the distance between the silicon wafer and the electrostatic electrode becomes large, and the ability to adsorb the silicon wafer becomes low. The thickness of the ceramic dielectric film is 100
˜1500 μm is preferred.

The ceramic dielectric film has a porosity of 5%.
Hereinafter, the maximum pore diameter is preferably 50 μm or less.
When the porosity exceeds 5%, the number of pores increases and the pore diameter becomes too large, so that the pores can easily communicate with each other. In the ceramic dielectric film having such a structure,
Withstand voltage will decrease. Furthermore, if the pore diameter of the maximum pores exceeds 50 μm, the withstand voltage at high temperature cannot be secured even if the oxide is present at the grain boundaries. Porosity is 0.0
1-3% is preferable, and the maximum pore diameter is 0.1-1.
0 μm is preferable.

Carbon is preferably contained in the ceramic dielectric film in an amount of 50 to 5000 ppm. This is because the electrode pattern provided in the electrostatic chuck can be hidden and high radiant heat can be obtained.
Also, the lower the volume resistivity, the higher the adsorption capacity of the silicon wafer in the low temperature range.

In the present invention, the reason why some pores may be present in the ceramic dielectric film is that the fracture toughness value can be increased, which improves the thermal shock resistance. be able to.

Examples of the electrostatic electrode include a sintered body of metal or conductive ceramic, a metal foil, and the like.
The metal sintered body is preferably made of at least one selected from tungsten and molybdenum. The metal foil is also preferably made of the same material as the metal sintered body. This is because these metals are relatively hard to oxidize and have sufficient conductivity as electrodes. In this case, the end portion of the metal foil is heated and pressed, or chemically or physically etched so as to have a pointed shape. Examples of the chemical etching include etching with an acid or alkali aqueous solution, and examples of the physical etching include ion beam etching and plasma etching. Further, as the conductive ceramic, tungsten,
At least one selected from molybdenum carbides can be used.

9 and 10 are horizontal sectional views schematically showing electrostatic electrodes in another electrostatic chuck. In the electrostatic chuck 20 shown in FIG. 9, a semicircular shape is formed inside the ceramic substrate 1. The chuck positive electrode electrostatic layers 22 and the chuck negative electrode electrostatic layers 23 are formed. In the electrostatic chuck shown in FIG. 10, the chuck positive electrode electrostatic layers 32a and 32b each having a shape obtained by dividing a circle into four inside the ceramic substrate 1 are formed. And chuck negative electrode electrostatic layers 33a and 33b are formed. Further, the two positive electrode electrostatic layers 22a and 22b and the two chuck negative electrode electrostatic layers 33a and 33b are formed to intersect with each other.

The cross sections of the ends of these electrostatic electrodes are also pointed, so that an electric field is concentrated along the ends of the electrostatic electrodes, and a large chucking force is attracted. Also, cracks are less likely to occur in the ceramic substrate. In the case of forming an electrode having a shape in which a circular electrode is divided, the number of divisions is not particularly limited and may be 5 or more, and the shape thereof is not limited to a fan shape.

As the electrostatic chuck of the present invention, for example, as shown in FIG. 3, a chuck positive electrode electrostatic layer 2 and a chuck negative electrode electrostatic layer 3 are provided between a ceramic substrate 1 and a ceramic dielectric film 4. And an electrostatic chuck 10 having a structure in which a resistance heating element 5 is provided inside the ceramic substrate 1.
As shown in FIG. 1 and FIG. 5, the chuck positive electrode electrostatic layer 2 and the chuck negative electrode electrostatic layer 3 are provided between the ceramic substrate 1 and the ceramic dielectric film 4, and the resistance heating element 25 is provided on the bottom surface of the ceramic substrate 1. An electrostatic chuck 201 having a configuration
As shown in FIG. 6, a chuck positive electrode electrostatic layer 2 and a chuck negative electrode electrostatic layer 3 are provided between a ceramic substrate 1 and a ceramic dielectric film 4, and a metal serving as a resistance heating element is provided inside the ceramic substrate 1. Electrostatic chuck 3 in which wire 7 is embedded
As shown in FIG. 01 and FIG. 7, the chuck positive electrode electrostatic layer 2 and the chuck negative electrode electrostatic layer 3 are provided between the ceramic substrate 1 and the ceramic dielectric film 4, and the thermoelectric element 81 is provided on the bottom surface of the ceramic substrate 1. An electrostatic chuck 401 having a structure in which the Peltier element 8 made of the ceramic plate 82 is formed can be used. In these electrostatic chucks, the cross sections of the end portions of the electrostatic electrode layer are all pointed, so that a large chucking force is attracted and cracks are unlikely to occur in the ceramic substrate.

In the present invention, as shown in FIGS. 3 to 7, the chuck positive electrode electrostatic layer 2 and the chuck negative electrode electrostatic layer 3 are provided between the ceramic substrate 1 and the ceramic dielectric film 4.
Since the resistance heating element 5 and the metal wire 7 are formed inside the ceramic substrate 1, connection portions (through holes) 16 and 17 for connecting these to the external terminals are required. The through holes 16 and 17 are formed by filling a refractory metal such as tungsten paste or molybdenum paste, or a conductive ceramic such as tungsten carbide or molybdenum carbide.

Further, the connecting portions (through holes) 16 and 17
The diameter is preferably 0.1 to 10 mm. This is because it is possible to prevent cracks and distortions while preventing disconnection. The external terminals 6 and 18 are connected using the through holes as connection pads (see FIG. 8D).

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 of the ceramic substrate 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 joint part of the thermocouple metal wire is
It is preferable that the diameter is equal to or larger than the wire diameter of each metal wire and is 0.5 mm or less. With such a configuration, the heat capacity of the joint portion is reduced, the temperature is accurate,
In addition, the current value is quickly converted. For this reason,
The temperature controllability is improved and the temperature distribution on the heated surface of the wafer is reduced. As the thermocouple, for example, JIS
-K-1602 (1980), such as
Type, R type, B type, S type, E type, J type, and T type thermocouples.

FIG. 11 is a sectional view schematically showing a support container 41 into which the electrostatic chuck of the present invention having the above-mentioned structure is fitted. The support container 41 has an electrostatic chuck 1
01 is fitted through the heat insulating material 45. The support container 11 has a refrigerant outlet 42.
Is formed so that the refrigerant is blown from the refrigerant inlet 44 and flows out from the suction port 43 through the refrigerant outlet 42. The action of this refrigerant cools the electrostatic chuck 101. You can do it.

Next, an example of a method of manufacturing an electrostatic chuck, which is an example of the ceramic substrate of the present invention, will be described with reference to FIGS.
It will be described based on the sectional view shown in FIG. (1) First, a powder of ceramic such as a nitride ceramic or a carbide ceramic is mixed with a binder and a solvent to obtain a green sheet 50. As the above-mentioned ceramic powder, for example, aluminum nitride powder containing oxygen can be used. Further, if necessary, a sintering aid such as alumina or sulfur may be added.

Since several or one green sheets 50 'to be laminated on the green sheet on which the electrostatic electrode layer printed body 51 to be described later is formed are layers to be the ceramic dielectric film 4, it is necessary. Therefore, the composition may be different from that of the ceramic substrate. However, it is usually desirable to use the same material for the ceramic dielectric film 4 and the ceramic substrate 1. This is because these are often sintered as one body, and the firing conditions are the same. However, when the materials are different, the ceramic substrate may be manufactured first, the electrostatic electrode layer may be formed thereon, and the ceramic dielectric film may be further formed thereon.

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 a doctor blade method to produce a green sheet 50.

If necessary, the green sheet 50 may be provided with through holes in the through holes for inserting the support pins of the silicon wafer, the recesses for embedding the thermocouple, the portions for forming the through holes, and the like. The through hole can be formed by punching or the like. The thickness of the green sheet 50 is preferably about 0.1 to 5 mm.

Next, the through holes of the green sheet 50 are filled with a conductor paste to obtain the through-hole printed bodies 53 and 54. Next, the conductor paste serving as an electrostatic electrode layer or a resistance heating element is formed on the green sheet 50. Print. The printing is performed so that a desired aspect ratio is obtained in consideration of the shrinkage rate of the green sheet 50, whereby the electrostatic electrode layer printed body 51,
The resistance heating element layer printed body 52 is obtained. The printed body is formed by printing a conductive paste containing conductive ceramics, metal particles and the like.

Carbide of tungsten or molybdenum is most suitable as the conductive ceramic particles contained in these conductive pastes. This is because it is difficult to oxidize and the thermal conductivity does not easily decrease. Further, as the metal particles, for example, tungsten, molybdenum, platinum, nickel or the like can be used.

The average particle diameter of the conductive ceramic particles and the metal particles is preferably 0.1 to 5 μm. This is because it is difficult to print the conductor paste when these particles are too large or too small. Examples of such paste include 85 to 97 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, α-terpineol, glycol. The paste for conductor prepared by mixing 1.5 to 10 parts by weight of at least one solvent selected from ethyl alcohol and butanol is most suitable.

Next, as shown in FIG.
A green sheet 50 having 1, 52, 53, 54;
A green sheet 50 'having no printed body is laminated.
Green sheet 5 with no printed body on the side where the resistance heating element is formed
Stacking 0'is because the end face of the through hole is exposed,
This is to prevent oxidation during firing for forming the resistance heating element. If firing is performed to form the resistance heating element with the end face of the through hole exposed, it is necessary to sputter a metal that is difficult to oxidize, such as nickel, and more preferably, coat with Au—Ni gold brazing. Good.

(2) Next, as shown in FIG. 8B, the laminated body is heated and pressed to form a laminated body of green sheets. At this time, since the conductor paste layer is pressed, if a conductor paste layer containing a suitable binder is formed in advance, the cross section of the end portion becomes a pointed shape. The heating temperature of the laminate is preferably 50 to 300 ° C., and the pressure during pressurization is preferably ²⁰ to 200 kg / cm ² . Then, the green sheet and the conductive paste are sintered. The temperature during firing is preferably 1000 to 2000 ° C., and the pressure applied during firing is preferably 100 to 200 kg / cm ² . These heating and pressurization are performed in an inert gas atmosphere. As the inert gas, argon, nitrogen or the like can be used. Through this firing step, the through holes 16 and 17, the chuck positive electrode electrostatic layer 2, the chuck negative electrode electrostatic layer 3, and the resistance heating element 5 whose end faces are pointed are formed.

(3) Next, as shown in FIG. 8C, bag holes 35 and 36 for connecting external terminals are provided. Blind hole 3
At least a part of the inner walls of the electrodes 5 and 36 is made conductive, and the conductive inner walls are connected to the chuck positive electrode electrostatic layer 2, the chuck negative electrode electrostatic layer 3, the resistance heating element 5, and the like. desirable.

(7) Finally, as shown in FIG.
External terminals 6 and 18 are provided in the bag holes 35 and 36 through a brazing filler metal. Further, if necessary, a bottomed hole may be provided and a thermocouple may be embedded inside the hole. Solder is silver-lead, lead-
Alloys such as tin and bismuth-tin can be used. The thickness of the solder layer is preferably 0.1 to 50 μm. This is because the range is sufficient to secure the connection with solder.

In the above description, the electrostatic chuck 101
Although the electrostatic chuck 201 (see FIG.
In the case of manufacturing), after manufacturing a ceramic plate having an electrostatic electrode layer, a conductor paste is printed on the bottom surface of the ceramic plate and fired to form a resistance heating element 25, and then electroless plating or the like. The metal coating layer 25a may be formed by. Further, when the electrostatic chuck 301 (see FIG. 6) is manufactured, a metal foil or a metal wire may be embedded in a ceramic powder as an electrostatic electrode or a resistance heating element and sintered. Further, in the case of manufacturing the electrostatic chuck 401 (see FIG. 7), after manufacturing a ceramic plate having an electrostatic electrode layer, a Peltier element may be bonded to this ceramic plate via a sprayed metal layer.

A conductor is provided on the surface and inside of the ceramic substrate of the present invention, the conductor layer on the surface is a chuck top conductor layer, and the conductor inside is at least one of a guard electrode and a ground electrode. In addition, the ceramic substrate functions as a wafer prober.

FIG. 12 is a sectional view schematically showing an embodiment of the wafer prober of the present invention, and FIG. 13 is a sectional view of FIG.
3 is a cross-sectional view taken along the line AA of the wafer prober shown in FIG. In this wafer prober 501, a groove 67 having a concentric circular shape in plan view is formed on the surface of a disk-shaped ceramic substrate 63, and a plurality of suction holes 68 for sucking a silicon wafer are provided in a part of the groove 67. And groove 67
The chuck top conductor layer 62 for connecting to the electrode of the silicon wafer is formed in a circular shape on most of the ceramic substrate 63 including.

On the other hand, on the bottom surface of the ceramic substrate 63, a resistance heating element 61 having a concentric circular shape in plan view as shown in FIG. 1 is provided in order to control the temperature of the silicon wafer. External terminals (not shown) are connected and fixed to both ends. Further, inside the ceramic substrate 63, a guard electrode 65 and a ground electrode 66 (see FIG. 13) each having a grid shape in plan view are provided to remove stray capacitors and noise. The cross sections of the end portions of the guard electrode 65 and the ground electrode 66 are pointed, so that cracks are unlikely to occur in the ceramic substrate. In the electrostatic chuck, the resistance heating element 61
May be provided inside the ceramic substrate 63. In this case, if the end portion of the resistance heating element 61 has a pointed cross section, cracks are less likely to occur in the ceramic substrate,
A heat storage phenomenon does not easily occur at the end of the resistance heating element 61. The materials of the guard electrode 65 and the ground electrode 66 may be the same as those of the electrostatic electrode.

The thickness of the chuck top conductor layer 62 is
1 to 20 μm is desirable. This is because if it is less than 1 μm, the resistance value becomes too high to function as an electrode, and if it exceeds 20 μm, peeling easily occurs due to the stress of the conductor.

As the chuck top conductor layer 62, for example, copper, titanium, chromium, nickel, noble metal (gold, silver,
At least one metal selected from refractory metals such as platinum), tungsten, molybdenum, etc. can be used.

In the wafer prober having such a structure, after mounting a silicon wafer having an integrated circuit formed thereon, a probe card having tester pins is pressed against this silicon wafer, and a voltage is applied while heating and cooling. Continuity test can be performed. In the case of manufacturing a wafer prober, for example, as in the case of an electrostatic chuck, first, a ceramic substrate in which a resistance heating element is embedded is manufactured, and then a groove is formed on the surface of the ceramic substrate. Then, the metal layer may be formed by performing sputtering, plating or the like on the surface portion where the groove is formed.

[0098]

The present invention will be described in more detail below. (Example 1) Production of electrostatic chuck (see FIG. 3) (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, 11.5 parts by weight of an acrylic binder, 0.5 parts by weight of a dispersant, and 53 parts by weight of an alcohol consisting of 1-butanol and ethanol are mixed together, and molding is performed by a doctor blade method. Thus, a green sheet having a thickness of 0.47 mm was obtained.

(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, 5.0 mm, through-holes for inserting semiconductor wafer support pins, and through-holes for connecting to external terminals were 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 conductive paste A
Was printed on the green sheet by screen printing to form a conductor paste layer. The printing pattern was a concentric pattern. Further, a conductor paste layer having an electrostatic electrode pattern having the shape shown in FIG. 4 was formed on another green sheet.

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 laminated on the upper side (heating surface) and 13 layers on the lower side of the green sheet 50 which has been subjected to the above-mentioned treatment, and a conductor paste including an electrostatic electrode pattern is formed on the green sheet 50'. A green sheet 50 on which layers are printed is laminated, two green sheets 50 'on which no tungsten paste is printed are further laminated thereon, and these are pressure-bonded at 130 ° C. and a pressure of 80 kg / cm ² to form a laminated body. Formed (FIG. 8A).

(4) Next, the laminate thus obtained was degreased in nitrogen gas at 600 ° C. for 5 hours, at 1890 ° C. and a pressure of 150.
Hot pressing was performed at kg / cm ² for 3 hours to obtain an aluminum nitride plate-shaped body having a thickness of 3 mm. This is cut into a 230 mm disk shape, and a plate-like body made of aluminum nitride having therein a resistance heating element 5 having a thickness of 6 μm and a width of 10 mm and a chuck positive electrode electrostatic layer 2 and a chuck negative electrode electrostatic layer 3 having a thickness of 10 μm. (FIG. 8B).

(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 was provided on the surface by blasting with C or the like.

(6) Further, the portions where the through holes are formed are cut out to form bag holes 35 and 36 (see FIG. 8).
(C)) Using gold brazing made of Ni-Au, the bag holes 35 and 36 were heated and reflowed at 700 ° C. to connect the external terminals 6 and 18 made of Kovar (FIG. 8D). In addition,
The connection of the external terminal 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 the bottomed holes to complete the manufacture of an electrostatic chuck having a resistance heating element. The ceramic substrate constituting the obtained electrostatic chuck was fractured so as to include the electrostatic electrode layer, and its cross section was observed with a scanning electron microscope (SEM). The result is shown in FIG. As is clear from FIG. 14, the end portion of the electrostatic electrode layer has a pointed cross section.

(Comparative Example 1) The same as Example 1, but 2
The green sheets were laminated without heating at 5 ° C. When observed with an electron microscope (500 times), the cross-section edge of both the electrostatic electrode and the resistance heating element had a surface perpendicular to the wafer processing surface.

(Embodiment 2) Wafer prober 201 (see FIG. 1)
(See 2) (1) 1000 parts by weight of aluminum nitride powder (manufactured by Tokuyama Corp., average particle size 1.1 μm), 40 parts by weight of yttria (average particle size 0.4 μm), and 530 parts by weight of alcohol consisting of 1-butanol and ethanol. The mixed composition obtained by mixing the parts is molded using a doctor blade method,
A green sheet having a thickness of 0.47 mm was obtained.

(2) Next, this green sheet is heated to 80 ° C.
After drying for 5 hours, a through hole for through hole for connecting the resistance heating element and the external terminal pin was provided by punching.

(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 conductive paste A. Further, 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 parts by weight of a dispersant were mixed to obtain a conductive paste B. .

Next, a grid-like printed material for guard electrode and printed material for ground electrode were printed on the green sheet by screen printing using the conductive paste A. Further, the conductive paste B was filled in the through holes for through holes for connecting to the terminal pins.

Further, 50 printed green sheets and 50 unprinted green sheets are laminated to form one sheet.
A laminated body was produced by integrating at 30 ° C. and a pressure of 80 kg / cm ² .

(4) Next, this laminated body was subjected to 6 in nitrogen gas.
Degreasing at 00 ℃ for 5 hours, 1890 ℃, pressure 150kg /
It was hot-pressed at cm ² for 3 hours to obtain an aluminum nitride plate-shaped body having a thickness of 3 mm. The plate-shaped body thus obtained has a diameter of 300.
A circular plate of mm was cut out to obtain a ceramic plate-like body. The size of the through hole 17 was 0.2 mm in diameter and 0.2 mm in depth.

In addition, the guard electrode 65 and the ground electrode 66
Has a thickness of 10 μm, the guard electrode 65 is formed at a position 1 mm from the wafer mounting surface, and the ground electrode 66 is formed at a position
It was 1.2 mm from the wafer mounting surface. In addition, the conductor non-formed region 66a of the guard electrode 65 and the ground electrode 66
The size of one side was 0.5 mm.

(5) After polishing the plate-like body obtained in (4) above with a diamond grindstone, a mask is placed and a blast treatment with SiC or the like is performed on the surface to form concave portions for thermocouples and wafer adsorption. Groove 67 (width 0.5 mm, depth 0.5 mm)
Was set up.

(6) Further, a layer for forming the resistance heating element 61 was printed on the surface facing the wafer mounting surface. The printing used conductive paste. The conductive paste used was Solbest PS603D manufactured by Tokuriki Kagaku Kenkyusho, which is used for forming through holes in printed wiring boards. This conductive paste is a silver / lead paste and contains lead oxide, zinc oxide,
The metal oxide containing silica, boron oxide, and alumina (the weight ratio of each is 5/55/10/25/5) was 7.5 parts by weight with respect to 100 parts by weight of silver.
Further, the silver had a scaly shape with an average particle size of 4.5 μm.

(7) The ceramic substrate 63 on which the conductive paste was printed was heated and fired at 780 ° C. to sinter silver and lead in the conductive paste and burn the ceramic substrate 63. Furthermore, nickel sulfate 30g / l, boric acid 30g
/ L, 30 g / l of ammonium chloride and 60 g / l of Rochelle's salt, the heater plate was immersed in an electroless nickel plating bath, and a thickness of 1 μm was formed on the surface of the resistance heating element 61, which was an empty sintered body of silver. A nickel layer (not shown) having a boron content of 1% by weight or less was deposited. Then, the heater plate was annealed at 120 ° C. for 3 hours. The resistance heating element made of a silver sintered body has a thickness of 5 μm,
The width was 2.4 mm, and the sheet resistivity was 7.7 mΩ / □.

(8) A titanium layer, a molybdenum layer, and a nickel layer were sequentially formed on the surface where the groove 67 was formed by a sputtering method. As an apparatus for sputtering, SV-4540 manufactured by Nippon Vacuum Technology Co., Ltd. was used. The sputtering conditions are atmospheric pressure 0.6 Pa, temperature 100 ° C.,
The power was 200 W and the sputtering time was adjusted by each metal within the range of 30 seconds to 1 minute. The thickness of the obtained film was 0.3 μm for the titanium layer, 2 μm for the molybdenum layer, and 1 μm for the nickel layer from the image of the fluorescent X-ray analyzer.
It was m.

(9) Nickel sulfate 30 g / l, boric acid 3
The ceramic substrate 63 obtained in (8) above was dipped in an electroless nickel plating bath consisting of an aqueous solution containing 0 g / l, 30 g / l ammonium chloride and 60 g / l Rochelle salt to form a metal layer formed by sputtering. A nickel layer having a thickness of 7 μm and a boron content of 1 wt% or less was deposited on the surface and annealed at 120 ° C. for 3 hours.
The surface of the resistance heating element does not carry an electric current and is not covered with electrolytic nickel plating.

Furthermore, potassium gold cyanide 2 g /
1, ammonium chloride 75 g / l, sodium citrate 50 g / l, and sodium hypophosphite 10 g / l in an electroless gold plating solution at 93 ° C. for 1 minute.
A gold plating layer having a thickness of 1 μm was formed on the nickel plating layer.

(10) An air suction hole 68 is formed in the groove 67 through the rear surface by drilling, and a blind hole (not shown) for exposing the through hole 16 is provided. Ni-Au alloy (Au 81.5% by weight, Ni1
Using a gold braze composed of 8.4% by weight and 0.1% by weight of impurities, reflow was performed by heating at 970 ° C., and external terminal pins made of Kovar were connected. Also, solder (tin 9
External terminal pins made of Kovar were formed through 0% by weight / 10% by weight of lead).

(11) Next, a plurality of thermocouples for temperature control were embedded in the recess to obtain a wafer prober heater 201.

The ceramic substrate has a maximum pore diameter of 2
In μm, the porosity was 1%. Although the temperature of the ceramic substrate was raised to 200 ° C., no dielectric breakdown occurred even when 200 V was applied. Further, the warp amount was also good at 1 μm or less.

(Comparative Example 2) Same as Example 2, but 2
The green sheets were laminated without heating at 5 ° C. As a result of observation with an electron microscope (500 times), both of the guard electrode and the ground electrode had cross-section end portions having a surface perpendicular to the wafer processing surface.

(Example 3) Alumina hot plate (see FIGS. 1 and 2) (1) Alumina: 93% by weight, SiO ₂ : 5% by weight, C
aO: 0.5 wt%, MgO: 0.5 wt%, TiO
₂ : 0.5% by weight, acrylic binder: 11.5 parts by weight, dispersant: 0.5 parts by weight, and a paste prepared by mixing 53 parts by weight of an alcohol consisting of 1-butanol and ethanol, according to the doctor blade method. Molding was performed to obtain a green sheet having a thickness of 0.47 mm. (2) Next, after drying these green sheets at 80 ° C. for 5 hours, the green sheets that need to be processed are punched to have diameters of 1.8 mm, 3.0 mm, 5.0 m.
There are provided a through hole for inserting the semiconductor wafer supporting pin of m and a through hole for connecting to an external terminal.

(3) 100 parts by weight of tungsten particles having an average particle diameter of 3 μm, 1.9 parts by weight of acrylic binder, α
-3.7 parts by weight of terpineol solvent and 0.2 of dispersant
Part by weight was mixed to prepare a conductor paste B. The conductive paste B was printed on the green sheet by screen printing to form a conductive paste layer. The printing pattern was a concentric pattern.

(4) Further, the conductor paste B was filled in the through holes for through holes for connecting the external terminals.
On the green sheet on which the pattern of resistance heating element is formed,
Further, 34 to 60 green sheets on which the tungsten paste is not printed are on the upper side (heating surface) and 13 are on the lower side.
Laminate 30 to 30 sheets at 130 ℃, 80kg / c
A laminate was formed by pressure bonding with a pressure of m ² .

(5) Next, the obtained laminated body was subjected to 6 in air.
Degreasing at 00 ℃ for 5 hours, 1600 ℃, pressure 150kg /
It was hot pressed at cm ² for 2 hours to obtain an alumina plate having a thickness of 3 mm. By changing the processing conditions and polishing conditions, a substrate having a diameter of 280 and a thickness of 19 mm was prepared. Inside thickness 6μ
A plate-shaped body made of alumina having a resistance heating element 5 of m and a width of 10 mm.

(6) Next, the plate-like body obtained in (3) 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 was provided on the surface by blasting with C or the like.

(7) Further, the portion where the through hole is formed is cut out to form a bag hole, and the bag hole is made of Ni-A.
Using gold solder made of u, heating reflow was performed at 700 ° C. to connect external terminals made of Kovar. 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.

(8) Next, a plurality of thermocouples for temperature control were embedded in the bottomed holes to complete the production of a hot plate having a resistance heating element.

(Comparative Example 3) Same as Example 3, but 2
The green sheets were laminated without heating at 5 ° C. According to an electron microscope observation (500 times), the cross-sectional end portion of the resistance heating element had a surface perpendicular to the wafer processing surface.

Example 4 Hot Plate Made of Aluminum Nitride (See FIGS. 1 and 2) (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 binder 11.5 parts by weight, dispersant 0.5 parts by weight, acrylic resin binder (Kyoeisha's trade name KC-600, acid value 17 KOHmg /
g) Using a paste prepared by mixing 8 parts by weight and 53 parts by weight of an alcohol composed of 1-butanol and ethanol,
Molded by doctor blade method, thickness 0.47
A green sheet of mm was obtained.

(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, 5.0 mm, through-holes for inserting semiconductor wafer support pins, and through-holes for connecting to external terminals were 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 conductive paste A
Was printed on the green sheet by screen printing to form a conductor paste layer. The printing pattern was a concentric pattern. Further, a conductor paste layer having an electrostatic electrode pattern having the shape shown in FIG. 10 was formed on another green sheet.

Further, the through holes for through holes for connecting the external terminals were filled with the conductor paste B. On top of the green sheet that has undergone the above processing, the green sheet on which the tungsten paste is not printed is placed on the upper side (heating side)
37 sheets, 13 sheets on the lower side, 130 ° C, 80 kg / cm ²
Were laminated under the pressure of.

(4) Next, the obtained laminated body was degreased in nitrogen gas at 600 ° C. for 1 hour, and at 1890 ° C. and a pressure of 150.
Hot press at kg / cm ² for 3 hours to remove carbon 81
A 3 mm thick aluminum nitride plate containing 0 ppm was obtained. This was cut into a disk shape of 230 mm to obtain a ceramic plate-shaped body having a resistance heating element having a thickness of 6 μm and a width of 10 mm and an electrostatic electrode inside.

(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 was provided on the surface by blasting with C or the like.

(6) Further, a part of the through hole for the through hole is cut out to form a concave portion, and a gold brazing material made of Ni-Au is used for this concave portion, and reflow is performed by heating at 700 ° C. to form an external terminal made of Kovar. I was connected. 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 the bottomed holes to complete the production of the ceramic heater (hot plate).

(Comparative Example 4) The same as Example 4, but 2
The green sheets were laminated without heating at 5 ° C. According to an electron microscope observation (500 times), the cross-sectional end portion of the resistance heating element had a surface perpendicular to the wafer processing surface.

[0141]Evaluation methods (1) Uniformity Thermo viewer (IR162012-made by Nippon Datum Co., Ltd.
0012) on the wafer mounting surface of the ceramic substrate.
Measure the temperature at each location in the
The temperature difference was calculated.

(2) Adsorption force The temperature was raised to 450 ° C., and measurement was performed using a load cell (Autograph AGS-50 manufactured by Shimadzu Corporation). (3) Thermal shock resistance The temperature was raised to 200 ° C., and this was put into water to examine whether cracks occurred. In Table 1, ∘ indicates that cracks did not occur and had thermal shock resistance, and x indicates that cracks occurred and there was no thermal shock resistance. (4) Leakage current 1kV between the originally insulated conductors in the ceramic substrate
Voltage is applied, and the leak current at 300 ° C. is measured with a withstand voltage tester (TOS-5051 manufactured by Kikusui Electronics Co., Ltd.) or an ultra high resistor (R8340 manufactured by Advantest).
Was measured using.

[0143]

[Table 1]

As is clear from Table 1 above, Examples 1 to
The ceramic substrate according to No. 4 is extremely excellent in both thermal uniformity and thermal shock resistance. Further, as is clear from Example 1 and Comparative Example 1, the electrostatic chuck according to Example 1 has a large chucking force.

[0145]

As described above, the ceramic substrate of the present invention has excellent soaking properties and thermal shock resistance, and when the above ceramic substrate is used as an electrostatic chuck, the chucking force also becomes large.

[Brief description of drawings]

FIG. 1 is a plan view schematically showing an example of a ceramic heater using a ceramic substrate of the present invention.

FIG. 2 is a partially enlarged sectional view of the ceramic heater shown in FIG.

FIG. 3 is a cross-sectional view schematically showing an example of an electrostatic chuck using the ceramic substrate of the present invention.

4 is a cross-sectional view taken along the line AA of the ceramic heater shown in FIG.

FIG. 5 is a sectional view schematically showing an example of an electrostatic chuck using the ceramic substrate of the present invention.

FIG. 6 is a sectional view schematically showing an example of an electrostatic chuck using the ceramic substrate of the present invention.

FIG. 7 is a sectional view schematically showing an example of an electrostatic chuck using the ceramic substrate of the present invention.

8A to 8D are cross-sectional views schematically showing a part of the manufacturing process of the electrostatic chuck shown in FIG.

FIG. 9 is a horizontal cross-sectional view schematically showing the shape of an electrostatic electrode that constitutes the electrostatic chuck according to the present invention.

FIG. 10 is a horizontal cross-sectional view schematically showing the shape of an electrostatic electrode forming the electrostatic chuck according to the present invention.

FIG. 11 is a cross-sectional view schematically showing a state in which the electrostatic chuck according to the present invention is fitted in a support container.

FIG. 12 is a cross-sectional view schematically showing a wafer prober using the ceramic substrate of the present invention.

13 is a sectional view schematically showing a guard electrode of the wafer prober shown in FIG.

FIG. 14 is an SEM photograph showing a fracture cross section of a ceramic substrate that constitutes the electrostatic chuck according to Example 1.

[Explanation of symbols]

1, 11, 63 Ceramic substrate 2, 22, 32a, 32b Chuck positive electrode electrostatic layer 3, 23, 33a, 33b Chuck negative electrode electrostatic layer 2a, 3a Semi-circular arc shaped portion 2b, 3b Comb tooth portion 4 Ceramic dielectric film 5 , 12, 25, 61 resistance heating elements 6, 13, 18 external terminals 7 metal wire 8 Peltier element 9 silicon wafer 10 ceramic heater 14 bottomed hole 15 through holes 16, 17, 19 through holes 20, 30, 101, 201, 301, 401 electrostatic chuck 25a metal coating layers 35, 36 bag hole 41 supporting container 42 refrigerant outlet 43 inlet 44 refrigerant inlet 45 heat insulating material 62 chuck top conductor layer 65 guard electrode 66 ground electrode 66a electrode non-forming region 67 groove 68 Suction hole 501 Wafer prober

Continued front page    F-term (reference) 3K034 AA02 AA04 AA11 AA21 BB06                       BB14 BC17 FA16 JA01                 3K092 PP20 QA05 QB31 QB43 QB44                       QB76 RF03 RF11 RF27 VV06                       VV22 VV34                 5F031 CA02 HA02 HA03 HA18 MA28                       MA32

Claims (5)

[Claims] 1. A ceramic substrate in which a conductor layer is formed inside a ceramic substrate, wherein an end portion of the conductor layer has a pointed cross section. 2. The ceramic substrate according to claim 1, wherein the conductor layer is a resistance heating element and functions as a hot plate. 3. The ceramic substrate according to claim 1, wherein the conductor layer is an electrostatic electrode and functions as an electrostatic chuck. 4. The ceramic substrate according to claim 1, wherein the conductor layer has a pointed portion having a width of 0.1 to 200 μm. 5. A method of manufacturing a ceramic substrate, comprising printing a conductor layer on a ceramic green sheet, pressurizing it with another green sheet while heating and integrating the same, and then sintering the ceramic.