JP2001199768A - Ceramic substrate for instrument for producing and inspecting semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ceramic substrate which has an improved sintering property, can prevent curvature and the deterioration of heat conductivity at high temperature, has a low heat capacity, can give a practically uniform temperature distribution to a wafer-loading surface, can prevent the breakage or the like of a semiconductor wafer caused by the ununiformity of temperature on the wafer-loading surface, and is used for an instrument for producing or inspecting semiconductors. SOLUTION: This ceramic substrate which has a conductive layer in the inner portion of the ceramic substrate or on its surface and is used for producing or inspecting semiconductors, characterized by comprising a nitride ceramic, containing oxygen in the nitride ceramic, and having a thickness of <=50 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic substrate used as a device for manufacturing or inspecting a semiconductor, such as a hot plate (ceramic heater), an electrostatic chuck, and a wafer prober.

[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 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] Such a technique is disclosed in Japanese Patent Laid-Open No. 11-4 / 1999.
No. 0330 discloses a ceramic 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 ceramic heater using blackened aluminum nitride.

[0005]

However, when the thickness of these heaters is reduced to 50 mm or less, 200 ° C.
It has been found that there is a problem of warpage and a decrease in thermal conductivity in a high temperature region exceeding the above range. Further, the inventors have found that such a problem also occurs in an electrostatic chuck or a wafer prober used in the high temperature region.

[0006]

Means for Solving the Problems Accordingly, the present inventors have:
As a result of intensive studies to solve the above-mentioned problems, when the thickness of the ceramic substrate is 50 mm or less, the above-mentioned sinterability is improved by adding a certain amount of oxygen to the substrate using the nitride ceramic to improve the sinterability. It has been found that the above problem can be solved, and the present invention has been completed.

That is, the present invention relates to a ceramic substrate for a semiconductor manufacturing / inspection apparatus having a conductor layer inside or on a surface of a ceramic substrate, wherein the ceramic substrate is made of a nitride ceramic, and the nitride ceramic contains:
A ceramic substrate for a semiconductor manufacturing / inspection apparatus, wherein oxygen is contained and the thickness of the ceramic substrate is 50 mm or less.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A ceramic substrate for a semiconductor manufacturing / inspection apparatus of the present invention is made of a nitride ceramic, the nitride ceramic contains oxygen, and the thickness of the ceramic substrate is: It is characterized by being 50 mm or less.

A ceramic substrate for a semiconductor manufacturing / inspection apparatus of the present invention (hereinafter, also referred to as a ceramic substrate for a semiconductor device)
In the above, since the thickness of the ceramic substrate is adjusted to 50 mm or less to suppress the increase in the overall weight, it is possible to prevent the heat capacity of the ceramic substrate from becoming too large, and to hinder the processing of semiconductor wafers. It is possible to obtain a ceramic substrate having a uniform temperature distribution to such an extent that there is no occurrence.

When the thickness of the ceramic substrate exceeds 50 mm, the heat capacity of the ceramic substrate becomes large. In particular, when the ceramic substrate is heated and cooled by providing a temperature control means, the temperature followability is reduced due to the large heat capacity. I will. The thickness of the ceramic substrate is more desirably 20 mm or less. If it exceeds 20 mm, the heat capacity cannot be said to be sufficiently small, and the temperature controllability and the temperature uniformity of the surface on which the semiconductor wafer is mounted (hereinafter, referred to as a wafer mounting surface) are likely to decrease. Especially 5m
m or less is optimal. The thickness is desirably 1 mm or more.

In the ceramic substrate for a semiconductor device according to the present invention, the semiconductor wafer is placed in a state in which the semiconductor wafer is brought into contact with the wafer mounting surface of the ceramic substrate, and the semiconductor wafer is supported by support pins or the like. In some cases, a certain interval is maintained.

However, when the thickness of the ceramic substrate is 50 m
When it is adjusted to m or less, since the conductor layer is provided inside or on the surface and the ceramic substrate is a nitride ceramic, the Young's modulus at a high temperature is reduced and warpage occurs. In addition, since the thermal conductivity of the nitride ceramic at a high temperature is low, the meaning of adjusting the thickness to 50 mm or less to reduce the heat capacity is neglected. That is, since the thermal conductivity becomes low, the temperature of the wafer mounting surface of the ceramic substrate cannot follow the rise or fall speed of the temperature of the resistance heating element,
Temperature followability as a heater is reduced. Therefore,
In order to improve the temperature followability of the heater, it is necessary to ensure the high-temperature thermal conductivity of the ceramic substrate. When the thickness of the ceramic substrate is 50 mm or less, in order to prevent the occurrence of warpage and ensure the thermal conductivity of the ceramic substrate, as described above, oxygen is contained in the ceramic substrate to improve the sinterability. It is only necessary to improve the mechanical (physical) properties of the ceramic substrate by improving the density and manufacturing a high-density ceramic substrate.

In the present invention, when the thickness of the substrate is 50 mm or less, the sinterability is improved by incorporating oxygen into the nitride ceramic, and the warpage and thermal conductivity at high temperatures are ensured.
Preferably, the oxygen content in the ceramic substrate is 0.1 to 5% by weight. If the content is less than 0.1% by weight, the sinterability is reduced and many pores are present inside,
Warpage at a high temperature occurs or thermal conductivity cannot be ensured. On the other hand, if it exceeds 5% by weight, oxides are unevenly distributed at the grain boundaries, and this oxide lowers the thermal conductivity and lowers the Young's modulus. Oxygen can be introduced by firing the raw material nitride ceramic in air, and oxygen can be introduced by adding various oxides described below as a sintering aid. The amount of oxygen can be adjusted by adjusting the proportion of the oxide, the temperature and the time for firing.

Incidentally, in the aluminum nitride sintered body described in Japanese Patent Application Laid-Open No. 9-315867, the oxygen content is 0.8%.
It discloses that the substrate may be used as a susceptor or an electrostatic chuck having a substrate of up to 1.2% by weight of a nitride ceramic sintered body. However, warpage or heat at high temperatures generated when the thickness is adjusted to 50 mm or less is disclosed. No problem such as ensuring conductivity is described, and it should be added that the novelty and inventive step of the present invention are not hampered by the existence of this publication.

The diameter of the ceramic substrate of the present invention is 200 m.
It is desirable that the number exceeds m. This is because the larger the plate exceeds 200 mm, the greater the warpage and the greater the effect of the present invention. In particular, it is desirable to be 12 inches (300 mm) or more. This is because it will become the mainstream of next-generation semiconductor wafers.

Preferably, the porosity of the ceramic substrate is 0 or 5% or less. This is because if the porosity exceeds 5%, the thermal conductivity decreases or warpage occurs at high temperatures. In the ceramic substrate for a semiconductor device of the present invention, it is desirable to use a ceramic substrate having a Young's modulus of 280 GPa or more in a temperature range of 25 to 800 ° C. It is desirable that pores do not exist in the ceramic, but when pores exist, the maximum pore diameter is desirably 50 μm or less. If the maximum pore diameter is 50 μm or less, dielectric breakdown hardly occurs even at a high temperature of 200 ° C. or more, and warpage hardly occurs even at a high temperature of 200 ° C. or more. For the maximum pore diameter, five samples prepared under the same conditions are prepared, the surface of each sample is mirror-polished, and 10 portions of the polished surface are photographed with an electron microscope at a magnification of 5000 times. , Pick the largest one. Then, the average value of the 50 selected pore diameters in the 50 photographs is defined as the maximum pore diameter of the ceramic substrate manufactured under the conditions.

If the Young's modulus is less than 280 GPa, the rigidity is too low, and it is difficult to reduce the amount of warpage during heating, and the warp may damage the semiconductor wafer. Examples of the nitride ceramic constituting the ceramic substrate for a semiconductor device of the present invention include metal nitride ceramics, for example, aluminum nitride, silicon nitride, boron nitride, titanium nitride and the like.

In the present invention, it is desirable to include a sintering aid in the ceramic substrate. As sintering aids,
For example, alkali metal oxides, alkaline earth metal oxides, can be used rare earth oxides, and among these sintering aids, particularly _{CaO, Y 2 O 3, Na} 2 O, L
i ₂ O and Rb ₂ O ₃ are preferred. The content of these is desirably 0.1 to 20% by weight. By using such an oxide, oxygen can be contained in the aluminum nitride sintered body as described above.

According to the present invention, 50 to 5
Desirably, it contains 000 ppm of carbon. By containing carbon, the ceramic substrate can be blackened, and radiant heat can be sufficiently used when used as a 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 carbon is used, a decrease in thermal conductivity at high temperatures can be prevented. Because. Therefore, depending on the application, both crystalline carbon and amorphous carbon may be used in combination. The carbon content is 200
~ 2000 ppm is more preferred.

In the case where carbon is contained in the ceramic substrate, it is desirable that the carbon be contained so that its brightness becomes N4 or less as a value based on JIS Z 8721. What has this level of brightness is the amount of radiant heat,
This is because the concealing property is excellent.

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 ceramic substrate for a semiconductor device of the present invention comprises:
A ceramic substrate used in an apparatus for manufacturing a semiconductor or inspecting a semiconductor. Specific examples of the apparatus include an electrostatic chuck, a wafer prober, a hot plate, and a susceptor.

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 comprises a semicircular arc portion 2a and a comb tooth portion 2b, and the chuck negative 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 order to control the temperature of the silicon wafer 9, a resistance heating element 5 having a concentric circular shape as shown in FIG. 3 is provided inside the ceramic substrate 1. at both ends of the external terminals 6 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.

The electrostatic chuck includes 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 for a semiconductor device will be described.

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, it is desirable that the ceramic dielectric film contains an alkali metal oxide, an alkaline earth metal oxide, and a rare earth 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 20 to
It is desirable that the thickness be 2000 μm. If the thickness of the ceramic dielectric film is less than 20 μm, a sufficient withstand voltage cannot be obtained because the film thickness is too thin, and the dielectric breakdown of the ceramic dielectric film occurs when a silicon wafer is placed and adsorbed. In some cases, the thickness of the ceramic dielectric film is 20
If the thickness exceeds 00 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 more preferably 50 to 1500 μm.

As the electrostatic electrode formed in the ceramic substrate, for example, a sintered body of a metal or a conductive ceramic, a metal foil and the like can be mentioned. 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. Also, as the conductive ceramic, tungsten,
At least one selected from carbides of 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.

Further, the two positive electrode electrostatic layers 22a and 22b and the two chuck negative electrode electrostatic layers 33a and 33b are formed so as 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.

The resistance heating element may be provided inside the ceramic substrate, as shown in FIG. 1, 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 metal particles used in the metal sintered body may be spherical, scaly, or a mixture of spherical and scaly.

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 amount 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 1-50 parts of titania 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 an external terminal to connect to the power supply.
Although it 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 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 for a semiconductor device of the present invention, and when the inside conductor is at least one of a guard electrode and a ground electrode, the ceramic substrate is Function as a wafer prober.

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, a heating element 49 having a concentric circular shape in plan view as shown in FIG. 3 is provided for controlling the temperature of the silicon wafer. Is an external terminal (not shown)
Is connected and fixed. Further, inside the ceramic substrate 43, a guard electrode 45 and a ground electrode 46 having a lattice shape in a plan view are formed in order to remove stray capacitors and noise.
(See FIG. 7). The materials of the guard electrode 45 and the ground electrode 46 may be the same as those of the electrostatic electrode.

The thickness of the chuck top conductor layer 42 is
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.

As the chuck top conductor layer 42, for example, copper, titanium, chromium, nickel, and noble metals (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 structure, 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.

Next, a method of manufacturing a ceramic substrate for a semiconductor device according to the present invention will be described with reference to a sectional view shown in FIG.

(1) First, after mixing a nitride ceramic powder with a binder and a solvent to prepare a mixed composition, the green sheet 50 is formed by molding.
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 above ceramic powder, for example, aluminum nitride or the like can be used, and if necessary, a 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 slurry obtained by mixing these is formed into a sheet 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 serving as 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 size 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 kind of binder selected from acrylic, ethyl cellulose, 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, a green sheet 5 having prints 51, 52, 53, 54
0 and a green sheet 50 'having no printed body are laminated. 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. is there. 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.

[0069]

The present invention will be described in more detail below.

(Examples 1 to 5) (see FIG. 9) (1) Aluminum nitride powder (average particle size: 1.1 μm)
100 parts by weight, manufactured by Tokuyama, yttria (average particle size:
0.4 μm) 0.5 parts by weight (Example 1), 1 part by weight (Example 2), 2 parts by weight (Example 3), 3 parts by weight (Example 4), 4 parts by weight (Example 5) A composition comprising 12 parts by weight of an acrylic binder and alcohol was spray-dried to prepare a granular powder.

(2) Next, the granulated powder was placed in a mold and formed into a flat plate to obtain a formed product (green). (3) Subsequently, the formed product was heated at 1800 ° C. under a pressure of 20.
Hot pressed at 0 kg / cm ² , and an aluminum nitride plate having a thickness of 45 mm (Example 1), 20 mm (Example 2), 10 mm (Example 3), 5 mm (Example 4), and 3 mm (Example 5) A solid was obtained.

Next, a disk having a diameter of 210 mm was cut out from the plate, and a ceramic plate (heater plate) was cut out.
91. Drilling is performed on this plate-like body to form a through hole 95 for inserting a support pin of a semiconductor wafer and a bottomed hole 94 for embedding a thermocouple (diameter: 1.
1 mm, depth: 2 mm).

(4) The heater plate 91 obtained in the above (3) is
The conductor paste was printed 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, and based on 100 parts by weight of silver, lead oxide (5% by weight), zinc oxide (55% by weight), silica (10% by weight), and boron oxide (25% by weight). And 7.5 parts by weight of a metal oxide comprising alumina (5% 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 conductor paste is printed is heated and fired at 780 ° C. to sinter silver and lead in the conductor paste and to bake the heater plate 91 onto 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 91 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) Screen printing is performed on the portion to which the external terminal 94 for securing the connection with the power source is to be attached.
It was formed by printing a Ni-Au 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. ) And a ceramic heater 90 shown in FIG. 9 was obtained.

(Comparative Examples 1 and 2) Basically the same as Example 5, except that the thickness of the ceramic substrate was 3 mm (Comparative Example 1) and 40 mm (Comparative Example 2), and yttria (average particle size: 0.4 μm) was not added at all.

Comparative Example 3 Basically the same as Example 5, except that the thickness of the substrate was 55 mm.

Comparative Example 4 Basically the same as in Example 1, except that the thickness of the substrate was 55 mm and no yttria was added. The heaters of Examples 1 to 5 and Comparative Examples 1 to 4 were heated to 400 ° C., and the amount of warpage and the thermal conductivity were measured. The oxygen content was also measured. Table 1 shows the results.

[0080]Evaluation method  1. Oxygen content Trial sintered under the same conditions as the sintered bodies according to Examples and Comparative Examples
The powder is ground in a tungsten mortar to make a powder, of which
Of 0.01g from the oxygen and nitrogen simultaneous analyzer
(TC-136 manufactured by LECO) and heat the sample
The oxygen content was measured at a temperature of 2200 ° C and a heating time of 30 seconds.
Specified.

2. Using the Kyocera warpage measuring device, trade name "Nanoway",
The amount of warpage in the X and Y directions was measured in a measurement range of 200 mm, and the larger one was adopted as the amount of warpage.

3. Thermal conductivity a. Equipment used Rigaku laser flash method thermal constant measurement device LF / TCM-FA8510B b. Test conditions Temperature: room temperature, 200 ° C, 400 ° C, 500 ° C, 70
0 ° C atmosphere ... vacuum c. Measurement method-Temperature detection in the specific heat measurement was performed by a thermocouple (platinel) bonded to the back surface of the sample with a silver paste. The room temperature specific heat measurement was further performed with a light receiving plate (glassy carbon) adhered to the upper surface of the sample via silicon grease, and the specific heat (Cp) of the sample was determined by the following equation (1).

[0083]

(Equation 1)

[0084] In the above equation (1), delta O is input energy, [Delta] T is the saturation value of the temperature rise of the sample, Cp
_Gc is the specific heat of glassy carbon, W _Gc is the weight of glassy carbon, Cp _SG is the specific heat of silicon grease, W _SG is the weight of silicon grease, and W is the weight of the sample.

[0085]

[Table 1]

[0086] 4. Heating time A voltage of 100 V was applied to the ceramic heaters according to the examples and comparative examples, and the time required to raise the temperature to 400 ° C. was measured. The temperature of the wafer heating surface 91b is determined by a thermoviewer (IR162012-0012 manufactured by Nippon Datum).
Was measured by

(Example 6) Production of electrostatic chuck (FIGS. 1 to 3) (see FIG. 8) (1) Next, 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, 0.5 parts by weight of a dispersant, an acrylic binder 0.1 part
Using a paste obtained by mixing 09 parts by weight and 53 parts by weight of alcohol composed of 1-butanol and ethanol, molding was performed by a doctor blade method to a thickness of 0.47 m.
m green sheet 50 was obtained.

(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 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 is cut out into a disk shape having a diameter of 300 mm, and a plate made of aluminum nitride having therein a resistance heating element 5 having a thickness of 6 μm and a width of 10 mm, a chuck positive electrostatic layer 2 and a chuck negative electrostatic layer 3 having a thickness of 10 μm. (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: 1.2 mm, depth: 2.0 mm) for a thermocouple was provided on the surface by blasting 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).
(C)) The gold holes made of Ni-Au were used in the blind holes 13 and 14 to heat and reflow at 700 ° C. to connect the external terminals 6 and 18 made of Kovar (FIG. 8D). In addition,
The connection of the external terminals is preferably 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 was measured in the same manner as in Examples 1 to 5. The resistance heating element of the ceramic substrate was energized to raise the temperature of the ceramic substrate to 500 ° C., and the amounts of warpage and thermal conductivity were measured in the same manner as in Examples 1 to 5. The oxygen content of the ceramic substrate was 1.6% by weight, the amount of warpage was 1 μm, and the thermal conductivity was 75 W / m · K.

(Embodiment 7) Wafer prober 201 (FIG. 6)
(1) 100 parts by weight of aluminum nitride powder (manufactured by Tokuyama Corporation, average particle size: 1.1 μm), yttria (average particle size: 0.1 μm).
4 μm) A mixed composition obtained by mixing 4 parts by weight, 0.9 parts by weight of the amorphous carbon obtained in Example 1, and 53 parts by weight of alcohol composed of 1-butanol and ethanol was mixed with a doctor blade method. And molded to a thickness of 0.
A 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 to an external terminal 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. Further, a conductive paste B was filled in a through hole for a through hole for connecting to an external terminal.

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) The plate obtained in the above (4) is polished with a diamond grindstone, a mask is placed on the plate, and a blast treatment with SiC or the like is performed on the surface to form a concave portion for a thermocouple and a wafer adsorption 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 bake 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 where the grooves 47 were formed by a sputtering method. 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 made of Kovar was connected by heating and reflowing at 970 ° C. using gold brazing consisting of 8.4% by weight and impurities of 0.1% by weight. In addition, solder (tin 90% by weight)
/ Lead 10% by weight) to form external terminals made of Kovar.

(11) Next, a plurality of thermocouples for temperature control were embedded in the recesses to obtain a wafer prober heater 201, and the oxygen content was measured in the same manner as in Examples 1 to 5.

The temperature of the ceramic substrate was raised to 200 ° C., and the amounts of warpage and thermal conductivity were measured in the same manner as in Examples 1 to 5. The oxygen content of the ceramic substrate is 1.8% by weight,
The warpage was 1 μm, and the thermal conductivity was 135 W / m · K.

[0111]

As described above, the ceramic substrate for a semiconductor manufacturing / inspection apparatus of the present invention is made of a nitride ceramic containing oxygen, so that the sinterability can be improved and the warpage at high temperatures can be improved. A decrease in thermal conductivity can be prevented. Further, the thickness of the ceramic substrate is 50 mm.
Therefore, the heat capacity can be reduced and a practically uniform temperature distribution can be given to the wafer mounting surface. Therefore, for example, when an object to be heated such as a semiconductor wafer is mounted on the ceramic substrate, it is possible to prevent breakage or the like due to non-uniform temperature of the wafer mounting surface.

[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 for a semiconductor manufacturing / inspection apparatus 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 which is an embodiment of the ceramic substrate for a semiconductor device 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 when a ceramic for a semiconductor device of the present invention is used as a heater.

[Explanation of symbols]

 101 electrostatic chuck 1, 43, 91 ceramic substrate 2, 22, 32a, 32b chuck positive electrode electrostatic layer 3, 23, 33a, 33b chuck negative electrode electrostatic layer 2a, 3a semi-circular portion 2b, 3b comb tooth portion 4 ceramic Dielectric film 5, 49, 92 Resistance heating element 6, 93 External terminal 9 Silicon wafer 11 Bottomed hole 12 Through hole 16, 17 Through hole 42 Chuck top conductor layer 45 Guard electrode 46 Ground electrode 47 Groove 48 Suction hole 93 Terminal 92a Metal coating layer 96 Support pin

Continued on the front page F term (reference) 3K092 PP20 QA05 QB61 QB69 QB76 RF03 RF11 UA05 VV26 VV40 4G001 BA09 BA36 BB31 BB73 BC13 BC17 BC22 BC35 BC42 BC52 BC55 BC73 BD38 BE32 BE33

Claims (3)

[Claims] 1. A ceramic substrate for a semiconductor manufacturing / inspection device having a conductor layer inside or on a surface of a ceramic substrate, wherein the ceramic substrate is made of a nitride ceramic, and the nitride ceramic contains oxygen. And a thickness of the ceramic substrate is 50 mm or less. 2. The ceramic substrate according to claim 1, wherein the porosity of the ceramic substrate is 0 or 5% or less. 3. The oxygen content in the ceramic substrate is as follows:
3. The ceramic substrate for a semiconductor manufacturing / inspection apparatus according to claim 1, wherein the content is 0.1 to 5% by weight.