JP2001233675A - Aluminum nitride sintered compact and ceramic substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aluminum nitride sintered compact excellent in mechanical strength without causing the falling off of ceramic particles from the surface or lateral faces and without producing particles. SOLUTION: This aluminum nitride sintered compact is characterized by comprising sulfur.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a sintered aluminum nitride suitable for a ceramic substrate used for a semiconductor manufacturing or inspection apparatus such as a hot plate (ceramic heater), an electrostatic chuck, a wafer prober, and the like. The present invention relates to a ceramic substrate having a conductor layer formed inside or on the surface of a nitride ceramic such as a sintered body and the like.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor manufacturing and inspection apparatus including an etching apparatus and a chemical vapor deposition apparatus, a heater using a metal base material such as stainless steel or an aluminum alloy, a wafer prober, and the like have been used. Has been used. However, the metal heater has a problem that the temperature control characteristic is poor, and the thickness is large, so that the heater is heavy and bulky, and further, the corrosion resistance to corrosive gas is also poor.

In order to solve such a problem, heaters using ceramics such as aluminum nitride instead of metal heaters have been developed. Such a ceramic heater has an advantage that the warpage of the substrate can be prevented without increasing the thickness because the rigidity of the ceramic substrate itself is high.

[0004] Japanese Patent Application Laid-Open No.
Japanese Patent No. 40330 discloses a heater in which a heating element is provided on the surface of a nitride ceramic. In addition, Japanese Patent Application Laid-Open
Japanese Patent No. 48669 discloses a heater using blackened aluminum nitride.

[0005]

However, in the test of the present inventors, these aluminum nitride sintered bodies were:
There has been a problem that ceramic particles fall off from the surface or side surface of the aluminum nitride sintered body to generate particles and adhere to the semiconductor wafer.

[0006]

Means for Solving the Problems The present inventors have studied how to prevent the generation of particles. As a result, instead of coating the surface with another substance or the like, It is recalled that it is only necessary to improve the adhesion itself at the boundaries of ceramic particles, and as a specific method for this, it is necessary to add sulfur to ceramic powder to form a molded body, and then fire it. The present invention has been completed.

The aluminum nitride sintered body of the present invention is characterized by containing sulfur. Further, the ceramic substrate of the present invention is a ceramic substrate having a conductor layer inside or on the surface thereof, wherein the ceramic substrate is made of a nitride ceramic, and the nitride ceramic contains sulfur. .

[0008] In such a ceramic substrate made of an aluminum nitride sintered body or a nitride ceramic, it is not clear why the inclusion of sulfur improves the adhesion at the boundary between the ceramic particles. It is presumed that the liquid phase sintering reaction is accelerated, or that sulfur forms a compound with oxygen and ceramic constituent elements (for example, Al for aluminum nitride and Si for silicon nitride) to strongly bond the ceramic particles together. are doing.

FIG. 10 is a scanning electron microscope (SE) showing a fracture cross section of an aluminum nitride sintered body containing sulfur.
M) Although it is a photograph, as shown in FIG. 10, the fracture cross section shows the properties of intragranular fracture (same as the fracture phenomenon in which the fracture occurs inside the particle, not at the boundary of the particle, the same as the intragranular fracture). Present. In the aluminum nitride sintered body or the ceramic substrate of the present invention, since the fracture cross section is transgranular, it is considered that there is no apparent defect and the bending strength is high.

On the other hand, FIG. 11 is an SEM photograph showing a fracture cross section of a conventional aluminum nitride sintered body. As shown in FIG. 11, the fracture cross section is a grain boundary fracture (a fracture occurs at a grain boundary). Phenomenon), and since the bonding force between the particles is not so large, if any external or thermal stress acts on the sintered body or chemical force acts on the sintered body, Although the particles were easily dropped and particles were easily generated, the present invention can solve such a problem.

Further, when the aluminum nitride sintered body and the ceramic substrate of the present invention contain sulfur and oxygen, when the ceramic powder containing oxygen and sulfur is fired, the sulfur and oxygen are mixed with each other. Presumably acts as a catalyst, or sulfur and oxygen combine with Al or Si to form a compound that crosslinks between the particles, and strongly bonds between the ceramic particles. Therefore, it is considered that particles hardly fall off and generation of particles can be suppressed.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The aluminum nitride sintered body of the present invention is characterized by containing sulfur.

The sulfur content is measured by a so-called glow discharge mass spectrometry (GD-MS method).
0.05 to 200 ppm (weight, hereinafter, all weight) is desirable. If it is less than 0.05 ppm, the effect of bonding between the ceramic particles is poor, and if it exceeds 200 ppm, the sinterability is reduced, and the bonding between the ceramic particles may be weakened. That is, 0.05 to 200 ppm
Can be said to be in a range suitable for exerting the effects of the present invention.

Particularly, the content of sulfur is 0.1 to 100 pp.
m is optimal. Does not hinder the sintering of aluminum nitride,
This is because the fracture cross section of the ceramic can be adjusted to the intragranular fracture. Sulfur may be present in the sintered body in the form of S atoms, S ions, or sulfur compounds,
Therefore, when producing a sintered body, the above compound can be added to the raw material powder. Examples of the sulfur compound include polyether sulfone (PES), polyphenylene sulfide (PPS), and polysulfone (P
And inorganic compounds such as calcium sulfate, sodium sulfate, zinc sulfide, iron sulfide, and calcium sulfide (CaS). These may be used alone or in combination of two or more.

The aluminum sintered body desirably contains oxygen, and the content thereof is 0.1 to 1%.
It is desirably 0% by weight. If the oxygen content is less than 0.1% by weight, the sinterability deteriorates, defects tend to occur at the grain boundaries, and the flexural strength at high temperatures may decrease. Is a defect and the strength at high temperature may be reduced.

The oxygen content is adjusted by heating the raw material powder in air or oxygen or by adding an oxide sintering aid. As the sintering aid, alkali metal oxides and alkaline earth metal oxides can be used, and among these sintering aids, CaO, Na ₂ O, Li ₂ O,
Rb ₂ O is preferred. Further, alumina or silica may be used. The content of these is desirably 0.1 to 20% by weight.

The porosity of the aluminum nitride sintered body is:
It is desirably 0 or 5% or less. 5% porosity
If the temperature exceeds the above, the thermal conductivity is lowered, and warping occurs at a high temperature. Also, when no pores are present, the charged voltage at a high temperature is particularly high, and conversely, when there are pores,
The fracture toughness value increases. Therefore, which design should be determined in consideration of required characteristics. It is not clear why the presence of the pores increases the fracture toughness, but it is presumed that the extension of the cracks is stopped by the pores. The porosity is desirably measured by the Archimedes method. In this method, a sintered body is pulverized to obtain a specific gravity, and a porosity is calculated from a true specific gravity and an apparent specific gravity.

When pores are present in the aluminum nitride sintered body, the maximum pore diameter is desirably 50 μm or less. If the pore diameter of the maximum pore exceeds 50 μm, it may not be possible to secure the withstand voltage characteristics at high temperatures, particularly at 200 ° C. or higher. More preferably, the pore diameter of the largest pore is 10 μm or less. 2
This is because the amount of warping at 00 ° C. or higher is reduced. The porosity and the pore diameter of the maximum porosity are as follows: pressurizing time during sintering, pressure,
The temperature is adjusted with additives such as SiC and BN. Since SiC and BN hinder sintering, pores can be introduced.

The measurement of the pore diameter of the largest pore is performed by preparing five samples, polishing the surface of the sample to a mirror surface, and photographing the surface at 10 places with an electron microscope at a magnification of 2000 to 5000 times. Then, the maximum pore diameter is selected from the photographed images, and the average of 50 shots is defined as the maximum pore diameter.

In the aluminum nitride sintered body of the present invention, the Young's modulus in a temperature range of 25 to 800 ° C. is desirably 280 GPa or more. Young's modulus is 2
If it is less than 80 GPa, the rigidity is too low, and it is difficult to reduce the amount of warpage during heating when forming a plate.

The above aluminum nitride sintered body is 50 to 5
Desirably, it contains 000 ppm of carbon. By containing carbon, the aluminum nitride sintered body can be blackened, and radiant heat can be sufficiently utilized when used as a ceramic heater. The carbon may be amorphous or crystalline. When amorphous carbon is used, a decrease in volume resistivity at high temperatures can be prevented, and when crystalline one is used,
This is because a decrease in thermal conductivity at a high temperature can be prevented. Therefore, depending on the application, both crystalline carbon and amorphous carbon may be used in combination. Further, the content of carbon is more desirably 200 to 2000 ppm.

Amorphous carbon is, for example, C, H, O
Hydrocarbons, preferably saccharides, can be obtained by calcining in air, and graphite powder can be used as the crystalline carbon.
Further, after the acrylic resin is thermally decomposed in an inert atmosphere, carbon can be obtained by heating and pressurizing, and by changing the acid value of the acrylic resin, the crystalline (amorphous) can be obtained. The degree can be adjusted.

Further, when carbon is contained in the aluminum nitride sintered body of the present invention, the lightness thereof is determined according to JIS.
It is desirable to include carbon so that the value based on the definition of Z 8721 is N4 or less. This is because a material having such a lightness is excellent in radiant heat and concealability of a conductor layer or the like embedded therein when used as a ceramic heater.

Here, the lightness N is defined as 0 for an ideal black lightness, 10 for an ideal white lightness, and the brightness of the color between these black lightness and white lightness. Each color is divided into ten so that the perception of the color is equal, and displayed by symbols N0 to N10. The actual measurement of lightness is N0 to N1
The comparison is made with the color chart corresponding to 0. Decimal point 1 in this case
The place is 0 or 5.

The aluminum nitride sintered body of the present invention can be used for the ceramic substrate of the present invention described below, and is particularly suitable as a ceramic substrate for a semiconductor manufacturing / inspection apparatus.

Next, the ceramic substrate of the present invention will be described. The ceramic substrate according to the present invention is characterized in that the ceramic substrate has a conductor layer inside or on the surface thereof, wherein the ceramic substrate is made of a nitride ceramic, and the nitride ceramic contains sulfur.

The content of sulfur in the nitride ceramic is determined by GD-MS as in the case of the aluminum nitride sintered body.
0.05 to 200 ppm is desirable,
0.1-100 ppm is optimal. Sulfur may be present in the nitride ceramics in the form of S atoms, S ions, or sulfur compounds, and therefore, when manufacturing a ceramic substrate, the above compounds can be added to the raw material powder. . Examples of the sulfur compound include the same compounds as in the case of the aluminum nitride sintered body.

When oxygen is contained in the ceramic substrate, the oxygen content is preferably 0.1 to 10% by weight, as in the case of the aluminum nitride sintered body. The oxygen content is adjusted by heating the raw material powder in air or oxygen or by adding an oxide sintering aid. Examples of the sintering aid include those similar to those of the aluminum nitride sintered body.

The porosity of the ceramic substrate is desirably 0 or 5% or less as in the case of the aluminum nitride sintered body. This is because if the porosity exceeds 5%, the thermal conductivity decreases, or warpage occurs at high temperatures. When no pores are present, the charged voltage at a high temperature is particularly high. Conversely, when pores are present, the fracture toughness increases. Therefore, which design should be determined in consideration of required characteristics.

When pores are present in the ceramic substrate, the pore diameter of the largest pore is desirably 50 μm or less as in the case of the aluminum nitride sintered body.

The Young's modulus of the ceramic substrate in the temperature range from 25 to 800 ° C. is desirably 280 GPa or more as in the case of the aluminum nitride sintered body.

In addition, the ceramic substrate is made of 50 to 5000 pp as in the case of the aluminum nitride sintered body.
m, preferably 200 to 200 m.
More preferably, it contains 2000 ppm of carbon. The carbon may be amorphous or crystalline as in the case of the aluminum nitride sintered body.

In the case where carbon is contained in the aluminum nitride sintered body, as in the case of the above-mentioned aluminum nitride sintered body, the carbon is contained so that the brightness becomes N4 or less at a value based on the provisions of JIS Z 8721. It is desirable to make it. This is because a material having such a lightness is excellent in radiant heat and concealing properties of a conductor layer or the like embedded therein.

The ceramic substrate of the present invention has a thickness of 5
0 mm or less is desirable. Ceramic substrate thickness is 50m
m, the heat capacity of the ceramic substrate increases,
In particular, when heating and cooling are performed with the provision of the temperature control means, the temperature followability is reduced due to the large heat capacity. The thickness of the ceramic substrate is more desirably 20 mm or less. 2
If it exceeds 0 mm, the heat capacity cannot be said to be sufficiently small, and the temperature controllability and the surface on which the semiconductor wafer is placed (hereinafter, referred to as
The temperature uniformity of the wafer mounting surface is easily reduced. Further, 1 to 5 mm is optimal.

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

As the nitride ceramic constituting the ceramic substrate of the present invention, a metal nitride ceramic, for example,
Examples include aluminum nitride, silicon nitride, boron nitride, and titanium nitride. Among these, the above-mentioned aluminum nitride is desirable.

The ceramic substrate of the present invention is suitable for use as, for example, a ceramic substrate for a semiconductor manufacturing / inspection apparatus used for an apparatus for manufacturing a semiconductor or inspecting a semiconductor. For example, an electrostatic chuck, a wafer prober, a hot plate (ceramic heater), a susceptor and the like can be mentioned. Further, the ceramic substrate of the present invention can be used in a temperature range of 150 ° C. or higher, preferably 200 ° C. or higher.

When the ceramic substrate of the present invention is used as a ceramic heater, the conductor layer inside or on the surface thereof is a heating element, and may be a metal layer of about 0.1 to 100 μm. There may be. Also, when used as an electrostatic chuck, the conductor layer is an electrostatic electrode, the RF electrode and the heating element are below the electrostatic electrode,
It may be formed as a conductor layer in a ceramic substrate. In the present invention, the heating element is 60% from the opposite side of the heating surface.
It is desirable to be located within the position. This is to ensure the distance from the heating element to the heating surface and to ensure uniform temperature of the heating surface. Furthermore, when used as a wafer prober, a chuck top conductor layer is formed as a conductor layer on the surface, and a guard electrode and a ground electrode are formed inside as a conductor layer.

In the ceramic substrate of the present invention, the semiconductor wafer is placed in a state of being in contact with the wafer mounting surface of the ceramic substrate, and the semiconductor wafer is supported by supporting pins or the like, and is fixed between the ceramic substrate and the substrate. In some cases.

FIG. 9 is a partially enlarged sectional view schematically showing a ceramic heater as an example of the ceramic substrate of the present invention. In FIG. 9, the support pins 96 are inserted through the through holes 95, and hold the silicon wafer 99. Support pin 96
The silicon wafer 99 from the transfer machine.
Can be received, the silicon wafer 99 can be placed on the ceramic substrate 91, or the silicon wafer 99 can be heated while being supported. A heating element 92 is formed on the bottom surface 91 a of the ceramic substrate 91, and a metal coating layer 92 a is provided on the surface of the heating element 92. In addition, a bottomed hole 94 is provided.
Insert thermocouple. The silicon wafer 99 is heated on the wafer heating surface 91b side. In the present invention, since the ceramic substrate 91 constituting the ceramic heater contains sulfur or sulfur and oxygen, the bonding force between the particles is strong, and the particles are very little dropped, so that the particles adhere to the silicon wafer. Can be prevented.

FIG. 1 is a longitudinal sectional view schematically showing an example of an electrostatic chuck which is an embodiment of the ceramic substrate for a semiconductor device according to the present invention, and FIG. 2 is a view showing the electrostatic chuck shown in FIG. 3 is a cross-sectional view of the electrostatic chuck shown in FIG. 1 along the line BB.

In this electrostatic chuck 101, a chuck positive electrode electrostatic layer 2 is provided inside a ceramic substrate 1 having a circular shape in plan view.
And an electrostatic electrode layer comprising a chuck negative electrode electrostatic layer 3 are embedded. A silicon wafer 9 is placed on the electrostatic chuck 101 and is grounded.

The ceramic layer formed on the electrostatic electrode layer so as to cover the electrostatic electrode layer functions as a dielectric film for adsorbing the silicon wafer. It is referred to as the film 4.

As shown in FIG. 2, the chuck positive electrode electrostatic layer 2 includes a semicircular arc portion 2a and a comb tooth portion 2b, and the chuck negative electrode electrostatic layer 3 also has a semicircular arc 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 to face each other so as to intersect the comb teeth portions 2b and 3b. Each of the negative electrode electrostatic layers 3 has a DC power supply of +
The side - the side are connected, the DC voltage V ₂ is adapted to be applied.

In addition, a resistance heating element 5 having a concentric circular shape in plan view as shown in FIG. 3 is provided inside the ceramic substrate 1 for controlling the temperature of the silicon wafer 9. at both ends of the external terminal pin 6 is connected, is fixed, so that the voltages V ₁ is applied. Although not shown in FIGS. 1 and 2, as shown in FIG. 3, the ceramic substrate 1 has a bottomed hole 11 for inserting a temperature measuring element and a support pin for supporting and raising and lowering the silicon wafer 9. (Not shown) are formed. Note that the resistance heating element 5 may be formed on the bottom surface of the ceramic substrate. Further, an RF electrode may be embedded in the ceramic substrate 1 as needed.

To make the electrostatic chuck 101 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, various processes such as CVD are performed on the silicon wafer 9. In the present invention, since the ceramic substrate 1 constituting the electrostatic chuck contains sulfur or sulfur and oxygen, the bonding force between the particles is strong. Therefore, by polishing the surface of the ceramic dielectric film 4, an extremely flat surface can be formed, and the chucking force of the silicon wafer can be increased. Further, since particles are very little dropped, it is possible to prevent particles from adhering to the silicon wafer.

The electrostatic chuck has an electrostatic electrode layer and a resistance heating element, and has, for example, a configuration as shown in FIGS. Hereinafter, members constituting the electrostatic chuck that are not described in the description of the ceramic substrate will be described.

The ceramic dielectric film 4 on the electrostatic electrode
Is preferably made of the same material as the other parts of the ceramic substrate. This is because green sheets and the like can be manufactured in the same process, and after laminating them, a ceramic substrate can be manufactured by firing once.

The ceramic dielectric film desirably contains carbon, as in the other parts of the ceramic substrate. This is because the electrostatic electrode can be hidden and radiant heat can be used. Further, the ceramic dielectric film desirably contains an alkali metal oxide and an alkaline earth metal oxide. This is because these act as sintering aids and can form a high-density dielectric film.

The thickness of the ceramic dielectric film is 5 to 1
Desirably, it is 500 μm. If the thickness of the ceramic dielectric film is less than 5 μm, a sufficient withstand voltage cannot be obtained because the film thickness is too thin, and a silicon wafer is placed on the silicon dielectric film.
When adsorbed, the dielectric breakdown of the ceramic dielectric film may occur, while the thickness of the ceramic dielectric film is 1500
If the thickness exceeds μm, the distance between the silicon wafer and the electrostatic electrode becomes long, and the ability to adsorb the silicon wafer is reduced. The thickness of the ceramic dielectric film is
50 to 1500 μm is more preferred.

Examples of the electrostatic electrode formed in the ceramic substrate 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. It is desirable that the metal foil is also made of the same material as the metal sintered body. This is because these metals are relatively hard to be oxidized and have sufficient conductivity as electrodes.
As the conductive ceramic, at least one selected from carbides of tungsten and molybdenum can be used.

FIGS. 4 and 5 are horizontal sectional views schematically showing electrostatic electrodes in another electrostatic chuck.
In the electrostatic chuck 20 shown in FIG. 5, a semicircular chuck positive electrode electrostatic layer 22 and a chuck negative electrode electrostatic layer 23 are formed inside the ceramic substrate 1. In the electrostatic chuck shown in FIG. Inside are formed chuck positive electrostatic layers 32a and 32b and chuck negative electrostatic layers 33a and 33b each having a shape obtained by dividing a circle into four parts.

The two positive electrode electrostatic layers 22a and 22b and the two chuck negative electrode electrostatic layers 33a and 33b are formed to cross each other. In the case of forming an electrode in which a circular electrode or the like is divided, the number of divisions is not particularly limited, and may be five or more, and the shape is not limited to a sector.

As shown in FIG. 1, the resistance heating element may be provided inside the ceramic substrate, or may be provided on the bottom surface of the ceramic substrate. When a resistance heating element is provided, a blowing port for a refrigerant such as air may be provided as a cooling means in a support container into which the electrostatic chuck is fitted.

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

The conductive ceramic may be at least one selected from carbides of tungsten and molybdenum.
Seeds can be used. Further, when a 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 shape of the metal particles used in the metal sintered body may be spherical or scaly. When these metal particles are used, they may be a mixture of the above-mentioned spheres and the above-mentioned flakes.

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

As the metal oxide, for example, oxidized
Lead, zinc oxide, silica, boron oxide (B _Two O_Three ), Al
At least one selected from Mina, Yttria and Titania
Species are preferred. These oxides have the resistance value of the resistance heating element.
Between the metal particles and the ceramic substrate without increasing the
This is because adhesion can be improved.

The content of the metal oxide is desirably from 0.1 to less than 10 parts by weight based on 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.

The ratio 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 oxide is 100 parts by weight, 10 parts by weight, 1 to 30 parts by weight of silica, 5 to 50 parts by weight of boron oxide, 20 to 7 parts of zinc oxide
0 parts by weight, alumina 1 to 10 parts by weight, yttria 1
-50 parts by weight and titania of 1-50 parts by weight are preferred.
However, it is desirable that the total be adjusted so that the total does not exceed 100 parts by weight. This is because these ranges can particularly improve the adhesion to the ceramic substrate.

When the resistance heating element is provided on the bottom surface of the ceramic substrate, it is desirable that the surface of the resistance heating element be covered with a metal layer. The resistance heating element is a sintered body of metal particles, and is easily oxidized when exposed, and the oxidation changes the resistance value. Therefore, oxidation can be prevented by coating the surface with a metal layer.

The thickness of the metal layer is desirably 0.1 to 10 μm. This is because the oxidation of the resistance heating element can be prevented 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. Among them, nickel is more preferable. The resistance heating element requires a terminal for connection to a power supply, and this terminal is attached to the resistance heating element via solder. Nickel prevents thermal diffusion of the solder. As connection terminals, terminal pins made of Kovar can be used.

When the resistance heating element is formed inside the heater plate, the surface of the resistance heating element is not oxidized, so that the 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 to be used as the resistance heating element, it is desirable to use a nickel foil or a stainless steel foil as a resistance heating element by forming a pattern by etching or the like. The patterned metal foil may be bonded with a resin film or the like. Examples of the metal wire include a tungsten wire and a molybdenum wire.

When a conductor is provided on the surface and inside of the ceramic substrate of the present invention, and the inside conductor is at least one of a guard electrode and a ground electrode, the ceramic substrate is replaced with a wafer prober. Function as

FIG. 6 is a sectional view schematically showing one embodiment of the wafer prober of the present invention, and FIG. 7 is a sectional view taken along line AA of the wafer prober shown in FIG. In the wafer prober 201, a groove 47 having a concentric circular shape in plan view is formed on the surface of the ceramic substrate 43 having a circular shape in plan view, and a plurality of suction holes 48 for sucking a silicon wafer are provided in a part of the groove 47. The chuck top conductor layer 42 for connecting to the electrode of the silicon wafer is formed in a circular shape on most of the ceramic substrate 43 including the groove 47.

On the other hand, on the bottom surface of the ceramic substrate 43, heating elements 49 having a concentric circular shape in plan view as shown in FIG. 3 are provided in order to control the temperature of the silicon wafer. Are connected and fixed to external terminal pins (not shown). Also, the ceramic substrate 4
Inside 3, a guard electrode 45 and a ground electrode 46 (see FIG. 7) having a lattice shape in plan view are provided for removing stray capacitors and noise. Guard electrode 45
The material of the ground electrode 46 may be the same as that of the electrostatic electrode.

The thickness of the chuck top conductor layer 42 is as follows.
1 to 20 μm is desirable. If the thickness is less than 1 μm, the resistance value becomes too high to function as an electrode, while if it exceeds 20 μm, the conductor tends to be peeled off due to the stress of the conductor.

The chuck top conductor layer 42 is made of, for example, copper, titanium, chromium, nickel, a noble metal (gold, silver,
At least one metal selected from refractory metals such as platinum, molybdenum, and the like can be used.

In the wafer prober having such a configuration, after a silicon wafer having an integrated circuit formed thereon is mounted thereon, a probe card having tester pins is pressed against the silicon wafer, and a voltage is applied while heating and cooling. To conduct a continuity test. In the present invention, the bonding force between the particles in the ceramic substrate 43 constituting the wafer prober is strong, the particles can be prevented from falling off, and the particles can be prevented from adhering to the silicon wafer to be mounted.

Next, a method of manufacturing a ceramic substrate according to the present invention will be described with reference to a cross-sectional view shown in FIG. 8, using a method of manufacturing an electrostatic chuck as an example.

(1) First, after mixing a nitride ceramic powder, sulfur or a sulfur compound with a solvent to prepare a mixed composition, the green sheet 50 is formed by molding.
Is prepared. When carbon is contained, the above-mentioned crystalline carbon or amorphous carbon is used and its amount is adjusted according to the desired properties. As the sulfur compound, an organic substance such as the above-mentioned thermoplastic resin or an inorganic substance such as calcium sulfate can be used. However, when an organic substance is used, it is advantageous because it itself becomes a binder. Further, a method in which a plate or powder of the above-mentioned inorganic compound is brought into contact with a sintered body, heated at 1500 to 1900 ° C., and thermally diffused can be adopted.

As the above-mentioned ceramic powder, for example, aluminum nitride or the like can be used, and if necessary, the above-mentioned sintering aid such as yttria may be added.

Since several or one green sheet 50 to be laminated on the green sheet on which the electrostatic electrode layer printed body 51 to be described later is formed is a layer to be a ceramic dielectric film, depending on the purpose and the like, The composition may be different from that of the ceramic substrate. Alternatively, a ceramic substrate may be manufactured first, an electrostatic electrode layer may be formed thereon, and a ceramic dielectric film may be formed thereon.

The binder is preferably at least one selected from an acrylic binder, ethyl cellulose, butyl cellosolve, and polyvinyl alcohol.
Further, as the solvent, at least one selected from α-terpineol and glycol is desirable. A paste obtained by mixing these is formed into a sheet shape by a doctor blade method to produce a green sheet 50.

The green sheet 50 may be provided with a through hole for inserting a support pin of a silicon wafer and a concave portion for burying a thermocouple as needed. Through holes and recesses
It can be formed by punching or the like. The thickness of the green sheet 50 is preferably about 0.1 to 5 mm.

(2) Next, a conductor paste to be an electrostatic electrode layer and a resistance heating element is printed on the green sheet 50. The printing is performed so as to obtain a desired aspect ratio in consideration of the shrinkage ratio of the green sheet 50, thereby obtaining the electrostatic electrode layer print body 51 and the resistance heating element layer print body 52. The printed body is formed by printing a conductive paste containing conductive ceramic, metal particles, and the like.

As the conductive ceramic particles contained in these conductive pastes, carbides of tungsten or molybdenum are most suitable. This is because it is hard to be oxidized and the thermal conductivity is hard to decrease. Further, as the metal particles, for example, tungsten, molybdenum, platinum, nickel and the like can be used.

The average particle diameter of the conductive ceramic particles and 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.

As such a paste, 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, ethylcellulose, butyl cellosolve and polyvinyl alcohol, α- A paste for a conductor prepared by mixing 1.5 to 10 parts by weight of at least one solvent selected from terpineol, glycol, ethyl alcohol and butanol is most suitable. Further, the holes formed by punching or the like are filled with a conductor paste to obtain through-hole prints 53 and 54.

(3) Next, as shown in FIG. 8A, the green sheet 5 having the prints 51, 52, 53, 54
And a green sheet 50 having no printed body. Several or one green sheet 50 is laminated on the green sheet on which the electrostatic electrode layer printed body 51 is formed. The reason why the green sheet 50 having no printed body is laminated on the side where the resistance heating element is formed is to prevent the end face of the through hole from being exposed and being oxidized during firing for forming the resistance heating element. . If baking for forming the resistance heating element is performed while the end face of the through hole is exposed, it is necessary to sputter a metal that is difficult to oxidize, such as nickel, and more preferably to coat it with Au-Ni gold solder. Is also good.

(4) Next, as shown in FIG. 8B, the laminate is heated and pressed to sinter the green sheet and the conductive paste. Heating temperature is 1000-20
The temperature and the pressure are preferably 100 to 200 kg / cm ^{2 at} 00 ° C., and the heating and pressurization are performed in an inert gas atmosphere. As the inert gas, argon, nitrogen, or the like can be used. In this step, the through holes 16, 1
7, a chuck positive electrode electrostatic layer 2, a chuck negative electrode electrostatic layer 3, a resistance heating element 5, and the like are formed.

(5) Next, as shown in FIG. 8C, blind holes 13 and 14 for connecting external terminals are provided. Blind hole 1
At least a part of the inner walls of the electrodes 3 and 14 are made conductive, and the conductive inner walls are connected to the chuck positive electrostatic layer 2, the chuck negative electrostatic layer 3, the resistance heating element 5, and the like. desirable.

(6) Finally, as shown in FIG.
External terminals 6 and 18 are provided in blind holes 13 and 14 via a brazing filler metal. Further, if necessary, a bottomed hole 12 can be provided, and a thermocouple can be embedded therein.

As the solder, alloys such as silver-lead, lead-tin, bismuth-tin and the like can be used. Note that the thickness of the solder layer is desirably 0.1 to 50 μm. This is because the range is sufficient to secure the connection by soldering.

In the above description, the electrostatic chuck 101
In the case of manufacturing a wafer prober, for example, as in the case of an electrostatic chuck, a ceramic substrate in which a resistance heating element is embedded is first manufactured, and then a ceramic substrate is manufactured. May be formed on the surface of the substrate, and then a metal layer may be formed by performing sputtering, plating, or the like on the surface portion where the groove is formed.

As described above, the aluminum nitride sintered body and the ceramic substrate of the present invention can be applied to a hot plate (ceramic heater), an electrostatic chuck, a wafer prober, a susceptor, etc. for semiconductor production and inspection. Hereinafter, the present invention will be described with reference to examples, but it goes without saying that the present invention is not limited to the examples.

[0088]

EXAMPLES (Examples 1 to 7) Ceramic heater (FIG. 9)
(1) Aluminum nitride powder (average particle size: 1.1 μm)
1000 parts by weight (made by Tokuyama), alumina (average particle size:
0.4 μm), 5 parts by weight, 10 parts by weight, 20 parts by weight, 30 parts by weight, 42 parts by weight, 42 parts by weight, 86 parts by weight, and CaS each 1.17 × 10 ^-4 parts by weight, 4.7 parts by weight.
× 10 ^-4 parts by weight, 2.3 × 10 ^-3 parts by weight, 0.023 parts by weight, 0.07 parts by weight, 0.12 parts by weight, 0.19 parts by weight, 120 parts by weight of an acrylic binder and alcohol The composition was spray-dried to produce seven types of granular powders.

(2) Next, the granular powder was put in a mold and molded into a flat plate to obtain a formed product (green). Drilling is performed on the formed body, and a portion serving as a through hole 95 for inserting a support pin of a semiconductor wafer and a portion serving as a bottomed hole for embedding a thermocouple (diameter: 1.1 mm, depth: 2)
mm) 94 was formed.

(3) The processed form is processed by 180
Hot pressing was performed at 0 ° C. under a pressure of 200 kg / cm ² to obtain a 3 mm-thick aluminum nitride plate. Next, a disk having a diameter of 210 mm was cut out from this plate to obtain a ceramic plate (heater plate) 91.

(4) A conductor paste was printed on the heater plate obtained in (3) by screen printing. The printing pattern was a concentric pattern. As the conductor paste, Solvest PS603D manufactured by Tokuri Chemical Laboratory, which is used for forming through holes in a printed wiring board, was used. This conductor paste is a silver-lead paste,
A metal oxide composed of lead oxide (5% by weight), zinc oxide (55% by weight), silica (10% by weight), boron oxide (25% by weight), and alumina (5% by weight) was added to 00 parts by weight. It contained 7.5 parts by weight. The silver particles had a mean particle size of 4.5 μm and were scaly.

(5) Next, the heater plate on which the conductive paste is printed is heated and fired at 780 ° C. to sinter silver and lead in the conductive paste and to bake the heater plate 91 on the heater plate.
A heating element 92 was formed. The silver-lead heating element has a thickness of 5μ.
m, the width was 2.4 mm, and the sheet resistivity was 7.7 mΩ / □.

(6) Nickel sulfate 80 g / l, sodium hypophosphite 24 g / l, sodium acetate 12 g / l,
The heater plate 11 prepared in the above (5) is immersed in an electroless nickel plating bath composed of an aqueous solution having a concentration of boric acid of 8 g / l and ammonium chloride of 6 g / l. A metal coating layer (nickel layer) 92a was deposited.

(7) Ni-A is screen-printed on the portion where the terminal for securing the connection with the power source is to be attached.
u was formed by printing a brazing agent. Then, an external terminal 93 made of Kovar is placed on this, a thermocouple for temperature control is inserted, and then connected with a gold solder of 81.7 Au-18.3Ni, and then heated at 1030 ° C. for fusion. 9) and the ceramic heater 90 of FIG. 9 was obtained. Alumina content in the ceramic substrate 91, and oxygen content measured by the following method,
The sulfur content is shown in Table 1.

(Test Examples 1 to 3) Alumina was added so as to have a content shown in Table 1, and CaS was added in an ion content of Table 1.
A ceramic heater 90 was obtained in the same manner as in Example 1, except that the ceramic heater 90 was added in such an amount as shown in FIG.

With respect to the ceramic heaters of Examples 1 to 7 and Test Examples 1 to 3, the oxygen content, the sulfur content, the bending strength, and the number of particles were measured by the following methods, and the fractured sections were observed. . The results are shown in Table 1.

(1) Measurement of Strength The strength was measured using an Instron universal tester (Model 4507).
Using a load cell of 500 kgf) in an atmosphere with a humidity of 400 ° C., a crosshead speed: 0.5 mm / min, a span distance L: 30 mm, a test specimen thickness: 3.06 mm, and a test specimen width: 4.03 mm. Then, the three-point bending strength σ (kgf / mm ² ) was calculated using the following calculation formula (1). In Table 1, the units are converted and expressed in MPa.

Σ = 3PL / 2wt ² (1)

In the above formula (1), P is the maximum load (kgf) when the test piece breaks, L is the distance between lower supports (30 mm), and t is the thickness of the test piece. Sa (m
m) and w is the width (mm) of the test piece. The results are shown in Table 1 below.

(2) Oxygen content A sample sintered under the same conditions as those of the sintered bodies according to the examples and comparative examples was pulverized in a tungsten mortar, and 0.01 g of this was pulverized.
And a simultaneous oxygen / nitrogen analyzer (TC- manufactured by LECO) under the conditions of a sample heating temperature of 2200 ° C. and a heating time of 30 seconds.
136).

(3) Sulfur content Glow discharge mass spectrometry (GD-MS method) was used. The analysis is based on the US "SHIVA TECHNO
LOGIES, INC "(Phone: 315-699-53)
32, FAX: 315-699-0349).

(4) Fracture cross section The fracture cross section was observed with an electron microscope of 2000 times,
If at least 50% of the visual fields of the electron micrograph were broken intragranularly, it was regarded as intragranular. Further, in the field of view of the electron microscope photograph at 2000 times, those in which the intragranular fracture was partially observed even if the intragranular fracture was less than 50% were partially regarded as the intragranular fracture.

(5) Measurement of Number of Particles After placing the silicon wafer and raising the temperature to 400 ° C., 10 places on the surface of the silicon wafer were observed with an electron microscope.
The number of particles exceeding 0.2 μm was measured and 1 cm ²
The number of particles per unit was calculated.

[0104]

[Table 1]

As is clear from Table 1, when the sulfur content is too small, it is difficult to adjust the fracture surface of the ceramic substrate to intragranular fracture. It is presumed that if the amount of sulfur is too small, the bonding effect between the particles becomes small. Even if the amount of oxygen is too large, it is difficult to make most of the particles intragranular. The number of particles generated in Examples 1 to 7 was 1 cm.
^The number was 40 or less per ² .

Example 8 Production of Electrostatic Chuck (FIGS. 1 to 3) (1) Next, 1000 parts by weight of aluminum nitride powder (manufactured by Tokuyama Corporation, average particle size 1.1 μm), yttria (average particle size: 0.4 μm) 40 parts by weight, boron nitride 1.3 × 1
0 ^-3 parts by weight, of acrylic binder 115 parts by weight, dispersing agent 5
A green sheet 50 having a thickness of 0.47 mm was obtained by using a paste obtained by mixing 0.3 parts by weight of polysulfone and 530 parts by weight of alcohol composed of 1-butanol and ethanol with a doctor blade method. Was.

(2) Next, these green sheets 50
After drying at 80 ° C. for 5 hours, a green sheet requiring processing is punched into a 1.8 mm-diameter.
A portion serving as a through hole for inserting a semiconductor wafer support pin of 0 mm and 5.0 mm and a portion serving as a through hole for connecting to an external terminal were provided.

(3) 100 parts by weight of tungsten carbide particles having an average particle diameter of 1 μm, acrylic binder 3.0
By weight, 3.5 parts by weight of the α-terpineol solvent and 0.3 parts by weight of the dispersant were mixed to prepare a conductor paste A. A conductive 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 parts by weight of a dispersant. This conductive paste A
Was printed on the green sheet 50 by screen printing to form a conductor paste layer. The printing pattern was a concentric pattern. Further, a conductor paste layer composed of an electrostatic electrode pattern having the shape shown in FIG. 2 was formed on another green sheet 50.

(4) Further, for connecting external terminals
The conductive paste B was filled in the through hole for the through hole.
Green sheet 50 on which pattern of resistance heating element is formed
Grease without printing tungsten paste
34 sheets 50 'on the upper side (heating surface) and 13 sheets on the lower side
And a conductor paper consisting of an electrostatic electrode pattern
The green sheets 50 on which the strike layers are printed are laminated,
Glee without tungsten paste printed on it
Sheets 50 'are laminated at 130 ° C and 80 ° C.
kg / cm ^Two To form a laminate (FIG. 8).
(A)).

(5) Next, the obtained laminate was degreased in a nitrogen gas at 600 ° C. for 5 hours, and at 1890 ° C. under a pressure of 150 ° C.
It was hot-pressed at kg / cm ² for 3 hours to obtain an aluminum nitride plate having a thickness of 3 mm. This was cut into a disk shape having a diameter of 300 mm, and a plate made of aluminum nitride having a resistance heating element 5 having a thickness of 6 μm and a width of 10 mm, and a chuck positive electrostatic layer 2 and a chuck negative electrostatic layer 3 having a thickness of 10 μm. (See FIG. 8 (b)).

(6) Next, the plate obtained in (3) is
After polishing with a diamond grindstone, a mask is placed and Si
A bottomed hole (diameter: 1.20 m, depth: 2.0 mm) for a thermocouple was formed on the surface by blast treatment with C or the like.

(7) Further, the portions where the through holes are formed are cut out to form blind holes 13 and 14 (FIG. 8).
(Refer to FIG. 8 (c)), and the external terminals 6 and 18 made of Kovar were connected to the blind holes 13 and 14 by heating and reflowing at 700 ° C. using gold brazing filler metal made of Ni—Au (see FIG. 8D). . The connection of the external terminals is desirably a structure in which a tungsten support is supported at three points. This is because connection reliability can be ensured.

(8) Next, a plurality of thermocouples for temperature control were embedded in the bottomed holes, and the manufacture of the electrostatic chuck having the resistance heating element was completed. The oxygen content of the ceramic substrate constituting the electrostatic chuck having the resistance heating element thus manufactured is 1.6% by weight, and the ion content is
It was 30 ppm. The ceramic substrate was operated by energizing the resistance heating element to raise the temperature of the ceramic substrate to 400 ° C., but no leakage current was observed.
The strength at a high temperature of 400 ° C. was as high as 400 MPa, and some of the ceramic substrates were broken intragranularly.

(Embodiment 9) The wafer prober 201 (FIG. 6)
(1) 1000 parts by weight of aluminum nitride powder (manufactured by Tokuyama Corporation, average particle size 1.1 μm), 40 parts by weight of yttria (average particle size 0.4 μm), 0.3 parts by weight of polyether sulfone, A mixed composition obtained by mixing 530 parts by weight of an alcohol consisting of butanol and ethanol was molded by a doctor blade method to a thickness of 0.47.
mm green sheet was obtained.

(2) Next, the green sheet is heated to 80 ° C.
After drying for 5 hours, a through hole for a through hole for connecting the 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, acrylic binder 3.0
Parts by weight, 3.5 parts by weight of α 部 terpineol solvent and 0.3 parts by weight of a dispersant were mixed to prepare a conductive paste A. A conductive 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 α @ terpineol solvent, and 0.2 parts by weight of a dispersant. .

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

Further, 50 printed green sheets and 50 unprinted green sheets were laminated and 1
A laminate was produced by integrating at 30 ° C. and a pressure of 80 kg / cm ² .

(4) Next, this laminate is placed in nitrogen gas for 6 hours.
Degreasing at 00 ° C for 5 hours, 1890 ° C, pressure 150kg /
Hot pressing was performed for 3 hours at ² cm ² to obtain a 3 mm-thick aluminum nitride plate. The obtained plate-like body was prepared with a diameter of 300
It was cut out into a circular shape of mm to obtain a ceramic plate. The size of the through hole 16 was 0.2 mm in diameter and 0.2 mm in depth.

The guard electrode 45 and the ground electrode 46
Is 10 μm, the formation position of the guard electrode 45 is 1 mm from the wafer mounting surface, and the formation position of the ground electrode 46 is
It was 1.2 mm from the wafer mounting surface. The conductor non-forming region 46a of the guard electrode 45 and the ground electrode 46
Of one side was 0.5 mm.

(5) After polishing the plate-like body obtained in the above (4) with a diamond grindstone, a mask is placed, and the surface is subjected to blasting treatment with SiC or the like to form a concave portion for a thermocouple and a wafer suction surface. Groove 47 (width 0.5 mm, depth 0.5 mm)
Was provided.

(6) Further, a layer for forming the heating element 49 was printed on the surface facing the wafer mounting surface. For printing, a conductive paste was used. As the conductive paste, Solvest PS603D manufactured by Tokuri Chemical Laboratory, which is used for forming through holes in a printed wiring board, was used. This conductive paste is a silver / lead paste, and a metal oxide composed of lead oxide, zinc oxide, silica, boron oxide, and alumina (the weight ratio of each is 5/55/10/25/5) is converted to silver 10
It contained 7.5 parts by weight with respect to 0 parts by weight. The silver had a scaly shape with an average particle size of 4.5 μm.

(7) The heater plate on which the conductive paste was printed was heated and fired at 780 ° C. to sinter silver and lead in the conductive paste and to sinter the ceramic substrate 43. Further, nickel sulfate 30 g / l, boric acid 30 g / l, ammonium chloride 30 g / l and Rochelle salt 60 g / l
The heater plate is immersed in an electroless nickel plating bath composed of an aqueous solution containing, and a nickel layer having a thickness of 1 μm and a boron content of 1% by weight or less (not shown) is formed on the surface of the silver sintered body 49.
Was precipitated. Thereafter, the heater plate was annealed at 120 ° C. for 3 hours. The heating element made of a silver sintered body had a thickness of 5 μm, a width of 2.4 mm, and a sheet resistivity of 7.7 mΩ / □.

(8) A titanium layer, a molybdenum layer, and a nickel layer were sequentially formed on the surface on which the grooves 47 were formed by sputtering. As a device for sputtering, SV-4540 manufactured by Japan Vacuum Engineering Co., Ltd. was used. The sputtering conditions were as follows: atmospheric pressure 0.6 Pa, temperature 100 ° C.,
The power was 200 W, and the sputtering time was adjusted for each metal within a range of 30 seconds to 1 minute. The thickness of the obtained film was determined from the image of the X-ray fluorescence spectrometer to be 0.3 μm for the titanium layer, 2 μm for the molybdenum layer, and 1 μm for the nickel layer.
m.

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

Further, 2 g of potassium potassium cyanide /
l, 75 g / l ammonium chloride, 50 g / l sodium citrate and 10 g / l sodium hypophosphite 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 48 to be drawn out from the groove 47 to the back surface is formed by drilling, and a blind hole (not shown) for exposing the through hole 16 is provided. A Ni-Au alloy (81.5% by weight of Au, Ni1
An external terminal pin made of Kovar was connected by heating and reflowing at 970 ° C. using a brazing filler metal consisting of 8.4% by weight and 0.1% by weight of impurities. External terminal pins made of Kovar were formed on the heating element via solder (90% by weight of tin / 10% by weight of lead).

(11) Next, a plurality of thermocouples for temperature control were buried in the recesses to obtain a wafer prober heater 201. The oxygen content of the ceramic substrate of the wafer prober thus manufactured was 1.6% by weight, and the ion content was 30 ppm.

Although the temperature of the ceramic substrate was raised to 200 ° C., no problem such as a short circuit occurred. In addition, 400
The flexural strength at ℃ was as high as 400 MPa, and the ceramic substrate was partially transgranular.

[0130]

As described above, in the aluminum nitride sintered body and the ceramic substrate of the present invention, the bond between the ceramic particles can be strengthened without reducing the strength due to the sulfur, and the number of particles can be reduced. be able to.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view schematically showing an electrostatic chuck which is an embodiment of a ceramic substrate of the present invention.

FIG. 2 is a sectional view taken along line AA of the electrostatic chuck shown in FIG.

FIG. 3 is a sectional view taken along line BB of the electrostatic chuck shown in FIG. 1;

FIG. 4 is a cross-sectional view schematically illustrating an example of an electrostatic electrode of the electrostatic chuck.

FIG. 5 is a cross-sectional view schematically illustrating an example of an electrostatic electrode of the electrostatic chuck.

FIG. 6 is a cross-sectional view schematically showing a wafer prober as one embodiment of the ceramic substrate of the present invention.

FIG. 7 is a sectional view taken along line AA of the wafer prober shown in FIG. 6;

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

FIG. 9 is a cross-sectional view schematically showing a ceramic heater as one embodiment of the ceramic substrate of the present invention.

FIG. 10 is a scanning electron microscope (SEM) photograph showing a fracture cross section of the aluminum nitride sintered body containing sulfur of the present invention.

FIG. 11 is a scanning electron microscope (SEM) photograph showing a fracture cross section of a conventional aluminum nitride sintered body.

[Explanation of symbols]

 Reference Signs List 101 electrostatic chuck 1, 43 ceramic substrate 2, 22, 32a, 32b chuck positive electrode electrostatic layer 3, 23, 33a, 33b chuck negative electrode electrostatic layer 2a, 3a semicircular portion 2b, 3b comb tooth portion 4 ceramic dielectric Membrane 5, 49 Resistance heating element 6, 18 External terminal pin 9 90 Silicon wafer 11 Bottom hole 12 Through hole 16 Through hole 42 Chuck top conductor layer 45 Guard electrode 46 Ground electrode 47 Groove 48 Suction hole 91 Ceramic substrate 92 Heating element 93 Terminal 92a Metal coating layer 96 Support pin

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) H05B 3/10 C04B 35/58 104A 5F045 3/20 393 H01L 21/30 541L 5F056 F term (reference) 3K034 AA02 AA03 AA04 AA05 AA08 AA10 AA15 AA16 AA34 AA37 BA06 BA13 BA14 BB06 BB14 BC04 BC17 CA02 CA17 CA25 CA27 DA04 FA13 HA01 HA10 JA10 3K092 PP03 PP20 QA05 QB02 QB26 QB31 QB43 QB49 QB62 QC02 QC25 RF03 BA11 BB03 BB02 SS0333 BB67 BB73 BC13 BC35 BC42 BD14 BD38 BE26 BE35 4M106 AA01 BA01 DH02 DJ40 5F031 CA02 HA02 HA18 HA33 HA37 MA28 MA32 PA26 5F045 BB15 DP02 EK09 5F056 BA08 CB21 CC04 EA14

Claims (6)

[Claims] 1. An aluminum nitride sintered body containing sulfur. 2. The sulfur content is 0.05 to 20.
The aluminum nitride sintered body according to claim 1, wherein the content is 0 ppm. 3. The aluminum nitride sintered body according to claim 1, wherein the aluminum nitride sintered body contains oxygen. 4. A ceramic substrate having a conductive layer inside or on a surface thereof, wherein the ceramic substrate is made of a nitride ceramic, and the nitride ceramic contains sulfur. 5. The sulfur content is 0.05 to 20.
The ceramic substrate according to claim 4, wherein the content is 0 ppm. 6. The ceramic substrate according to claim 4, wherein said ceramic substrate contains oxygen.