JP2001135869A - Thermocouple and ceramic base material for semiconductor manufacturing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ceramic base material which is, when used as a ceramic heater, easily controlled for temperature while excellent in temperature uniformity on a heating surface, as well as a heating body used for the heater. SOLUTION: A ceramic base material is provided wherein a temperature control means is provided on the surface or inside a ceramic plate, with a thermocouple provided inside the substrate. Here, the thermocouple comprises 2 different kinds of metal wires jointed together while the size of the joint part is the same with the diameter of element wire of metal wires or smaller than the larger-diameter element wire by 0.5 mm or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic heater or electrostatic chuck used for drying or sputtering semiconductor products mainly used in the semiconductor industry.
A ceramic substrate for a semiconductor manufacturing device having a function as a wafer prober and the like, and a thermocouple used for the ceramic substrate, particularly a ceramic for a semiconductor manufacturing device which is easy to control the temperature and is excellent in securing the temperature uniformity of a heated surface. We propose a technique for obtaining a substrate.

[0002]

2. Description of the Related Art An electronic circuit of a semiconductor product is formed by applying a photosensitive resin as an etching resist on a silicon wafer and then etching. In this case, since the photosensitive resin applied to the surface of the silicon wafer has been applied by a spin coater or the like, it is necessary to dry it after application. The drying process is
This is performed by placing a silicon wafer coated with a photosensitive resin on a heater and heating. Conventionally, as such a heater, a heater in which a heating element is wired on the back surface of a substrate made of a metal plate (aluminum plate) is used.

[0003]

However, when such a heater made of a metal substrate is used for drying a semiconductor product, there are the following problems. Since the substrate of the heater is made of metal, the thickness of the substrate must be increased to 15 mm or more. This is because, in a thin metal substrate, warpage or distortion occurs due to thermal expansion caused by heating, and the wafer placed on the substrate is damaged or tilted. In addition, the conventional heater has a problem that it is heavy and bulky due to its thickness.

Further, when the heating temperature of the heater is controlled by changing the voltage or current applied to the heating element attached to the substrate, if the thickness of the substrate is large, the temperature of the heater substrate may fluctuate in the voltage or current. However, there is also a problem that the temperature control characteristic of the substrate is poor.

On the other hand, in Japanese Patent Publication No. 8-8247, a nitride ceramic substrate having a heating element is used, and the temperature of the ceramic plate is controlled while measuring the temperature in the vicinity of the heating element. Ceramic heaters have been proposed.

[0006]

However, when a silicon wafer is to be heated using such a ceramic heater, there is a problem in that a biased temperature distribution is inevitably generated on the heater surface, and the silicon wafer is damaged. Was.

Accordingly, an object of the present invention is to provide a ceramic base material provided with functions as a ceramic heater, an electrostatic chuck, and a wafer prober which are easy to control the temperature and have excellent temperature uniformity on a heating surface, and to be attached to the base material. An object is to provide a heating element.

[0008]

In order to achieve the above-mentioned object, the inventors of the present invention have studied the causes of silicon wafer breakage. It has been found that the main reason for the occurrence of the temperature distribution is that the responsiveness of the thermocouple is poor. And
As a result of further research, the reason that the thermocouple response is not sufficient is that the junction of the thermocouple (metal wire junction) is spherical and the heat capacity of this part is large, so that the temperature It has been found that this is because the current value is not converted. Therefore, the inventors focused on a method in which the two metal wire joints were not melted as in the related art and then crimped to form a spherical shape, but were joined by spot heating the joint with laser light. This method slims down the shape of the joint,
We succeeded in improving the temperature controllability of the thermocouple itself.

That is, according to the present invention, in a thermocouple in which two different types of metal wires are joined, the size of the joining portion of each of the metal wires is equal to or smaller than the element diameter of each metal wire. We propose a thermocouple for ceramic substrates characterized by a size of 0.5 mm or less, though large.

Further, the present invention provides a temperature control means on the surface or inside of a ceramic plate, joins two different types of metal wires to the ceramic plate, and adjusts the size of the joining portion to each metal wire. A ceramic substrate for a semiconductor manufacturing apparatus is provided, wherein a thermocouple having a size equal to or larger than the element wire diameter but smaller than 0.5 mm is provided.

The ceramic substrate according to the present invention desirably has a ceramic heater function. Further, as for the ceramic substrate of the present invention, an embodiment in which an electrostatic chuck is provided by embedding an electrostatic electrode inside a ceramic plate is preferable. Further, the ceramic substrate of the present invention has a guard electrode and a ground electrode embedded therein, and has a wafer prober function by forming a chuck top conductor layer on the semiconductor wafer mounting surface on the plate surface. Embodiments are preferred.

In each of the above configurations of the present invention, the ceramic plate is provided with a bottomed hole drilled from the side opposite to the heating surface, and it is desirable to insert a thermocouple into the bottomed hole and attach it. The distance between the bottom of the hole and the heating surface should be between 0.1 mm and
It is desirable that the thickness be about 1/2 of the thickness of the ceramic plate. Further, the thermocouple may be attached (contact-held) to the surface of the ceramic plate without providing the bottomed hole. In this case, the thermocouple may be directly attached to the surface of the ceramic plate, or may be indirectly attached via an insulating material or a heat conductive medium. For example, it is adhered and fixed with an inorganic adhesive, or is attached by pressing with a bolt or pin or the like and pressing. It is desirable to use a nitride ceramic or a carbide ceramic as a material of a ceramic plate constituting such a ceramic heater. Also,
As the heating element of the ceramic heater, it is desirable to use a heating element divided into at least two or more circuits.
The heating element is desirably a plate having a flat cross section.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a heating element or a Peltier element can be used as a temperature control means embedded in a ceramic plate. Further, as a thermocouple formed by joining the free ends of two different types of metal wires, the size of the joining portion, that is, the diameter of the joining portion is equal to or larger than the wire diameter of each metal wire. However, those having a diameter of 0.5 mm or less are used (see FIG. 4). By adopting such a configuration, the heat capacity concentrated on the joining portion is reduced, the temperature can be accurately and quickly converted to a current value, and the temperature controllability is improved, and when this is applied to a heater, The bias of the temperature distribution on the wafer heating surface can be reduced. In addition, as an example of the combination of the metal wires of the thermocouple, for example, JIS-C-1602 (19)
K type, R type, B type, S type as shown in 80)
Examples include a type, an E type, a J type, and a T type thermocouple. Among them, a K type thermocouple is preferable as a heating element of the ceramic heater. It should be noted that the K type refers to Ni / Cr alloy wire and N
Combination of i alloy, R type is Pt-13% Rh alloy wire and P
Combination with t line, B type is a combination of Pt-30% Rh alloy wire and Pt-65Rh alloy wire, S type is Pt-1
The combination of a 0% Rh alloy wire and a Pt wire, and the E type is Ni /
Combination of Cr alloy wire and Cu / Ni alloy wire, J type
Combination of Fe wire and Cu / Ni alloy wire, T type is Cu
It is a combination of a wire and a Cu / Ni alloy wire.

[0014] The size of the metal wire constituting the heating element
(Cross section diameter) is preferably about 0.1 to 0.3 mm. The size of the joint (D) is the same as the element diameter (d) of the metal wire, or at most 0.5 mm or less.
Preferably, it is about 0.2 to 0.3 mm. Thus, the reason for limiting the size specifically is that if the size of the joint (D) is about the same as the wire diameter (d), there is no extra heat capacity and the temperature change can be accurately determined. This is because it can be converted into a current, and as a result, accurate temperature measurement can be performed. Therefore,
Since the heating state of the heating element is adjusted based on the accurate temperature measurement result, the object to be heated can be uniformly heated.

As a method of manufacturing such a thermocouple, two kinds of metal wires are brought into contact with each other, and a laser beam is irradiated with a pulse (10 ⁻⁶ to 10 ⁻⁴ seconds) to perform spot heating. As the laser light, a carbon dioxide laser, an excimer laser,
An ultraviolet laser or the like can be used. As described above, when the joint portion 4c of the metal wires 4a and 4b is spot-heated by irradiating a laser beam with a pulse, the joint portion 4c does not have a "bump-like" shape like the conventional thermocouple 4 'shown in FIG. It is.
The metal wires 4a and 4b of the thermocouple 4 are covered with polyimide or an insulating pipe 20 so as not to contact each other.

Next, an example in which the ceramic substrate for a semiconductor manufacturing apparatus according to the present invention is formed as a ceramic heater will be described first. As shown in FIG. 2, a ceramic base for forming a ceramic heater has a basic shape in which a heating element 2 preferably having a flat cross section is embedded in the surface or inside of a ceramic plate 1. I do. On the surface of the ceramic plate 1 opposite to the heating surface 1a on which the object to be heated is placed, there is provided a thermocouple housing bottomed hole 3 pierced and opened toward the heating surface. Then, the joining end side of the thermocouple 4 is inserted into the bottomed hole 3. The bottomed hole 3 is filled with a gold solder such as an Au-Ni alloy together with the thermocouple 4 and fixed, or the bottomed hole 3 is filled with a heat-resistant resin or ceramic together. It may be fixed. In addition, the bottomed hole 3
Without providing an organic adhesive on the surface of the ceramic plate 1a.
It may be bonded and fixed via an inorganic adhesive, a brazing material 25 or the like, or may be pressed and fixed with a bolt or a pin.
FIG. 8 shows an example in which the thermocouple 4 is fixed with an adhesive.

The ceramic plate 1 is preferably a nitride ceramic or a carbide ceramic. These ceramics have a coefficient of thermal expansion smaller than that of metal and have much higher mechanical strength than metal, so that even if the thickness is reduced, they do not warp or warp due to heating. Therefore, the substrate can be made thin and light. Furthermore, since the ceramic plate 1 made of these materials has a high thermal conductivity and a small thickness, the surface temperature of the plate can quickly follow a temperature change of the heating element. That is, when the temperature of the heating element is changed by changing the voltage and the current value, the surface temperature of the ceramic plate 1 can be quickly controlled.

In the ceramic heater constructed using the ceramic base material of the present invention, the heating element 2 is connected to the ceramic plate 1.
(See FIG. 3), and the opposite surface is configured as a heating surface 1a on which an object to be heated such as a silicon wafer is placed and heated.
And the burying position is eccentrically arranged in the thickness direction from the center of the thickness, and the surface farther from the heating element 2 is a heating surface 1a (see FIG. 2). desirable.

By arranging the heating element 2 on the ceramic plate 1 as described above, while the heat generated from the heating element 2 propagates to the heating surface 1a, it diffuses throughout the substrate, and The temperature distribution on the surface that heats 5 (such as a silicon wafer) is made uniform, and as a result, the temperature in each part of the object 5 is made uniform.

For example, FIG. 1 is a bottom view schematically showing an example in which the ceramic substrate according to the present invention is configured as a ceramic heater. This ceramic heater is a bottom surface of a ceramic plate 1 formed in a disk shape. The heating element 2 is
In order to heat the ceramic plate 1 so that the temperature distribution over the entire heating surface (the surface opposite to the illustrated bottom surface) becomes uniform,
It is formed in a concentric or spiral pattern. These heating elements 2 form a pair of adjacent double concentric circles,
It has a configuration in which the wires are connected so as to form a single line, and terminal pins 6 serving as input / output terminals are connected to both ends. A through hole 8 for inserting a support pin 7 for supporting the object 5 to be heated is formed in a portion near the center of the ceramic plate 1, and a temperature measuring element, that is, a thermocouple 4 is also inserted. Hole 3 is also formed.

In the ceramic heater having such a configuration, the thickness of the ceramic plate 1 is preferably 0.5 to 5 mm. If it is thinner than 0.5 mm, it is easily broken, while 5 m
When the thickness is more than m, heat is difficult to propagate, and the heating efficiency is deteriorated.

It is desirable to use a nitride ceramic or a carbide ceramic as the ceramic plate material. Examples of the nitride ceramic include aluminum nitride, silicon nitride, boron nitride, and titanium nitride. These may be used alone or in combination of two or more. Also, as a carbide ceramic,
For example, silicon carbide, zirconium carbide, titanium carbide,
Examples include tantalum carbide and tungsten carbide. These may be used alone or in combination of two or more. Of these, aluminum nitride is most preferred. This is because the thermal conductivity is the highest, 180 W / m · K, and is excellent in temperature followability.

In the above ceramic heater, the distance between the bottom of the bottomed hole 3 and the heating surface 1a (see FIG. 2B) L
Is preferably 0.1 mm to 1/2 of the thickness of the ceramic plate. If the distance L is less than 0.1 mm, a non-uniform temperature distribution occurs on the heating surface due to heat radiation. On the other hand, if this distance exceeds の of the ceramic plate, it becomes susceptible to the temperature of the heating element 2, so that it becomes impossible to control the temperature and an uneven temperature distribution is formed on the heating surface. is there.

The diameter of the bottomed hole 3 is 0.3 mm to 5 mm.
Is desirable. This is because if it is too large, the heat dissipation will be large, and if it is too small, the workability will be reduced and the distance to the heating surface cannot be equalized.
The bottomed holes 3 are desirably arranged symmetrically with respect to the center of the ceramic substrate 1 so as to form a cross, as shown in FIG. This is so that the temperature of the entire heating surface can be measured.

It is preferable that a temperature measuring element, that is, a thermocouple 4 is inserted into the bottomed hole 3, and then the inside of the hole is sealed with a heat-resistant resin or ceramic. Examples of such a heat-resistant resin include a thermosetting resin, particularly, an epoxy resin, a polyimide resin, a bismaleimide-triazine resin, and the like. These resins may be used alone or in combination of two or more. As the ceramic, alumina sol, silica sol, or the like can be used. These ceramic sols can be fixed by drying and gelling. In the present invention, the alumina sol and the silica sol may be dried and gelled in a state in which the thermocouple 4 is in contact with the surface of the ceramic plate 1 without providing the bottomed hole 3 so as to be adhered and fixed. Alternatively, it may be fixed by pressing with a bolt or a pin and pressing.

In the above ceramic heater, the heating element 2 as one of the temperature control means is preferably divided into at least two or more circuits as shown in FIG.
It is more desirable to divide the circuit into 0 circuits. The reason is,
This is because, by dividing the circuit, the amount of heat generated can be finely changed by controlling the power supplied to each circuit, and the temperature of the heating surface 1a such as a silicon wafer can be accurately controlled.

As the wiring pattern of the heating element 2, in addition to the concentric circles shown in FIG. 1, for example, a spiral, an eccentric circle, a bent line and the like can be mentioned.

In the above ceramic heater, the heating element 2
Is formed on the surface of the ceramic plate 1, a conductive paste containing metal particles is applied to the surface of the ceramic plate 1 to form a conductive paste layer having a predetermined pattern.
The method of baking and sintering is preferred. The sintering of the metal particles is sufficient if the metal particles and the metal particles and the ceramic are fused.

When the heating element 2 is formed on the surface of the ceramic plate 1, the thickness of the heating element 2 is preferably about 1 to 30 μm, more preferably 1 to 10 μm. On the other hand, the heating element 2
Is formed inside the ceramic plate 1, its thickness is preferably 1 to 50 μm.

When the heating element 2 is formed on the surface of the ceramic plate 1, the width of the heating element 2 is preferably 0.1 to 20 mm, more preferably 0.1 to 5 mm. On the other hand, when the heating element 2 is buried inside the ceramic plate 1, the width of the heating element 2 is preferably about 5 to 20 μm.

The resistance of the heating element 2 can be changed by changing its width and thickness, but the above range is most practical. The resistance value becomes larger as the heating element 2 is formed inside the ceramic substrate 1, and both the thickness and the width can be made larger when the heating element 2 is formed inside the ceramic substrate 1. In particular, when the heating element 2 is buried inside, the distance between the heating surface 1a and the heating element 2 is shortened, and the uniformity of the temperature of the heating surface 1a may be reduced. Therefore, the width of the heating element 2 itself is increased. There is a need. In the case where the heating element 2 is buried inside the ceramic plate 1, there is no need to consider the adhesion to the nitride ceramic or the like. Therefore, as a material for the heating element, a high melting point metal such as tungsten or molybdenum or the like is used. Tungsten and molybdenum carbide can be used. Further, since such a heating element can have a high resistance value, the thickness itself may be increased for the purpose of preventing disconnection or the like. It is desirable that the heating element in this case also has the above-described thickness and width.

The cross section of the heating element 2 in the width direction may be rectangular or elliptical in diameter, but is desirably formed in a flat so-called plate shape. This is because a flat cross section facilitates the uniform transmission of heat toward the heating surface, making it difficult to achieve a non-uniform temperature distribution on the heating surface. The degree of the flattening is desirably about 10 to 5000 in terms of a sectional aspect ratio (width of the heating element / thickness of the heating element).
Adjusting to this range can increase the resistance value of the heating element 2 and ensure the uniformity of the temperature of the heating surface 1a.

That is, assuming that the thickness of the heating element 2 is constant, if the aspect ratio is smaller than the above range, the amount of heat propagation in the direction of the heating surface of the ceramic plate 1 becomes small, and the pattern of the heating element 2 An approximate non-uniform temperature distribution is generated on the heating surface, and conversely, if the aspect ratio is too large, the temperature immediately above the center of the heating element 2 becomes high, which eventually approximates the pattern of the heating element 2. Temperature distribution occurs. Therefore, in consideration of the temperature distribution, the aspect ratio of the cross section is preferably set to about 10 to 5000 as described above.

When the heating element 2 is formed on the surface of the ceramic plate 1, the aspect ratio of the section is 10 to 20.
0, when the heating element 2 is formed inside the ceramic plate 1, it is more preferable that the cross-sectional aspect ratio is 200 to 5000. In this regard, when the heating element 2 is formed inside the ceramic plate 1, the cross-sectional aspect ratio can be increased. This means that, when the heating element 2 is provided inside, the distance between the heating surface 1a and the heating element 2 is shortened, and the temperature uniformity of the heating surface is reduced by that much, so that the heating element 2 itself is made flatter. This is necessary.

The heating element 2 can be buried eccentrically in the thickness direction of the inside of the ceramic plate 1, but at a position opposite to the heating surface 1 a of the ceramic plate 1. At a position close to the (bottom surface), it is desirable to set the position to be more than 50% and up to 99% of the distance from the heating surface 1a to the bottom surface. If the burial position is less than 50%,
Since the temperature is too close to the heating surface, a non-uniform temperature distribution is generated. Conversely, if the eccentric amount exceeds 99%, the ceramic plate 1 warps and the silicon wafer to be processed at the time of heating is generated. May be damaged.

When the heating element 2 is embedded inside the ceramic plate 1, the heating element forming layer may be provided in a plurality of layers. In this case, the patterns of the respective layers are in a mutually complementary relationship, that is, the heating element 2 of any layer has a heating surface 1.
When viewed from above a, it is desirable to make sure that a pattern is formed in any area. As such a structure, for example, a structure in which the arrangement is staggered with respect to each other can be given.

There is no particular limitation on the conductor paste for forming a heating element, but one containing metal particles or conductive ceramic for ensuring conductivity, and containing a resin, a solvent, a thickener, etc. preferable.

Next, a method of manufacturing the above ceramic heater will be described. (1) Step of mixing ceramic powders such as nitride ceramics and carbide ceramics with a binder and a solvent to obtain a green sheet (formed form): In the process of this step, the ceramic powders include aluminum nitride and carbonized Silicon or the like can be used, and a sintering aid such as yttria may be added as necessary. The binder is preferably at least one selected from an acrylic binder, ethyl cellulose, butyl cellosolve, and polyvinylal. Further, the solvent is desirably at least one selected from α-terpione and glycol. The conductive paste obtained by mixing them is formed into a sheet by a doctor blade method to produce a green sheet. A through hole 8 for inserting the support pin 7 for the silicon wafer 5 and a bottomed hole 3 for embedding the thermocouple 4 can be opened in the green sheet as needed. These through holes 8 and bottomed holes 3 can be formed by applying a punching method or the like. The thickness of the green sheet is preferably about 0.1 to 5 mm. When the thermocouple 4 is provided on the surface of the ceramic plate, no opening is required.

(2) A step of printing a conductive paste serving as a heating element on the green sheet: In the process of this step, a portion of the green sheet on which the heating element 4 is formed is made of conductive material such as metal particles or conductive ceramic. Apply or print the paste. These conductive pastes contain conductive metal particles and conductive ceramic particles. Examples of such metal particles include noble metals (gold, silver,
Platinum, palladium), lead, tungsten, molybdenum,
Nickel is preferred. These may be used alone or in combination of two or more. This is because these metals are relatively hard to oxidize and have a resistance value sufficient to generate heat. Further, as the conductive ceramic particles, tungsten or molybdenum carbide is most suitable. This is because it is difficult to be oxidized and the thermal conductivity is not easily reduced. These may be used alone or as a mixture.

As such a conductive paste, metal particles or conductive ceramic particles: 85 to 97 parts by weight,
At least one kind of binder selected from acrylic, ethylcellulose, butyl cellosolve and polyvinylal: 1.5 to 10 parts by weight, and at least one kind of solvent selected from α-terpione and glycol: 1.5 to 10
A tungsten paste or a molybdenum paste mixed and adjusted by weight is most suitable.

The particle size of the metal particles or the conductive ceramic particles contained in the conductive paste is 0.1 to 100.
μm is preferred. If it is smaller than 0.1 μm, it is easily oxidized. On the other hand, if it is larger than 100 μm, sintering becomes difficult and the resistance value increases. The shape of the metal particles 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. When the metal particles are scaly, or a mixture of spherical and scaly, it is easy to hold the metal oxide between the metal particles,
This is advantageous because the adhesion between the heating element and the nitride ceramic or the like can be ensured and the resistance value can be increased.

Examples of the resin contained in the conductor paste include an epoxy resin and a phenol resin. Examples of the solvent include isopropyl alcohol. Examples of the thickener include cellulose and the like. As described above, it is desirable to add a metal oxide to metal particles and sinter this to a conductor paste to be a heating element. Thus, by sintering the metal oxide together with the metal particles, the adhesion between the metal ceramic and the nitride ceramic or carbide ceramic as the ceramic plate 1 is improved. It is not clear why mixing the metal oxide with the metal particles in the conductive paste improves the adhesion with the nitride ceramic or the carbide ceramic. The surface of is slightly oxidized to form an oxide film, and this oxide film sinters and integrates through the metal oxide, and the metal particles and the nitride ceramic or carbide ceramic adhere to each other. It is thought that there is not.

The metal oxide is preferably at least one selected from the group consisting of, for example, lead oxide, zinc oxide, silica, boron oxide (B ₂ O ₃ ), alumina, yttria and titania. This is because these oxides can improve the adhesion between the metal particles and the nitride ceramic or the carbide ceramic without increasing the resistance value of the heating element 2.

The ratio of the above-mentioned lead oxide, zinc oxide, silica, boron oxide (B ₂ O ₃ ), alumina, yttria, and titania is as follows: 1-10, silica 1-30, boron oxide 5-50, zinc oxide 20-70, alumina 1
-10, yttria 1-50, titania 1-50, and the total is preferably adjusted within a range not exceeding 100 parts by weight. By adjusting the amounts of these oxides in these ranges, the adhesion to the nitride ceramic can be particularly improved. The amount of the metal oxide added to the metal particles is preferably 0.1% by weight or more and less than 10% by weight.

Further, when the heating element 2 is formed using the conductor paste having such a configuration, the sheet resistivity is 1 to 45.
mΩ / □ is preferred. When the sheet resistivity exceeds 45 mΩ / □, the amount of heat generated becomes too large with respect to the applied voltage,
This is because it is difficult to control the amount of heat generated by a ceramic heater having a heating element provided on the surface of a ceramic plate. If the addition amount of the metal oxide is 10% by weight or more, the sheet resistivity exceeds 50 mΩ / □, the calorific value becomes too large, the temperature control becomes difficult, and the uniformity of the temperature distribution decreases. .

When the heating element 2 is formed on the surface of the ceramic plate 1, a metal coating layer (see FIG. 3) 9 is preferably formed on the surface of the heating element 2. This is to prevent the internal metal sintered body (heating element 2) from being oxidized to change the resistance value. The thickness of the metal coating layer 9 is preferably 0.1 to 10 μm. The metal used for forming the metal coating layer 9 is not particularly limited as long as it is a non-oxidizing metal, and specifically, for example, gold, silver,
Palladium, platinum, nickel and the like can be mentioned. These may be used alone or in combination of two or more.
Of these, nickel is preferred.

(3) A green sheet on which the conductive paste for the heating element 2 obtained in the step (2) is printed and a green sheet on which the paste obtained in the same step as the step (1) is not printed Step of laminating at least one or more sheets each: In this step, if two or more layers of green sheets are laminated, the green sheet with the conductive paste for the heating element of (2) above (meaning the heating surface side) It is important that the number of green sheets laminated in (1) is smaller than the number of green sheets laminated in (1) below, and that the embedding position of the heating element 2 is eccentric in the thickness direction. . Specifically, 20 to 50 sheets are stacked on the upper side, and 5 to 20 sheets are stacked on the lower side.

(4) A step of heating and pressing the green sheet laminate to sinter the green sheet and the conductive paste to form a ceramic substrate and a heating element. The heating element 2 has terminals for connecting to a power supply. This terminal is necessary, and this terminal is attached to the heating element 2 via solder. Nickel is preferable because it prevents heat diffusion of the solder. As connection terminals,
For example, the terminal pin 6 made of Kovar is mentioned. In addition,
When the heating element 2 is formed inside the ceramic plate 1,
Since the surface of the heating element 2 is not oxidized, the above-described coating 9 is unnecessary. When the heating element 2 is formed inside the ceramic plate 1, a part of the heating element 2 may be exposed on the surface, and through holes 23 and 24 for connecting the heating element 2 may be provided.
May be provided in the terminal portion, and the external terminal connecting pins 6 may be connected and fixed to the through holes 23 and 24.
When connecting the external terminal connection pins 6, as the solder,
Alloys such as silver-lead, lead-tin, and bismuth-tin can be used. The thickness of the solder layer is 0.1 to 50 μm
Is preferred. This is because the range is sufficient to secure connection by soldering.

In this step, the heating temperature is 100
The pressure is from 0 to 2000 ° C. and the pressure is from 100 to 200 kg / cm ² in an inert gas atmosphere. As the inert gas, argon, nitrogen and the like can be used.

(5) Finally, openings for inserting external terminal connection pins 6 are formed in the through holes (connection pads) 23 and 24. Then, after solder paste is printed as a brazing material in the opening, the external terminal connecting pins 6 are inserted, heated, and reflowed. Heating temperature is 2
00-500 ° C is preferred. Further, the thermocouple 6 can be embedded as needed.

Next, a method of using the above ceramic heater will be described with reference to FIG. First, the control unit 15
When the power is supplied to the ceramic heater by operating the ceramic substrate 1, the temperature of the ceramic substrate 1 itself starts to rise, but the surface temperature of the outer peripheral portion becomes slightly low. Thermocouple 4
First, the data measured in step (1) is stored in the storage unit (16). Next, the temperature data is sent to a calculation unit 17, which calculates a temperature difference ΔT at each measurement point, and further calculates data ΔW necessary for uniforming the temperature of the heating surface 1a. Calculate. For example, the heating element 2a and the heating element 2
b has a temperature difference ΔT, and if the heating element 2a is lower, Δ
Calculates power data ΔW such that T is set to 0, transmits the calculated data to the control unit 15, and generates electric power based on the calculated data.
And raise the temperature.

Regarding the algorithm for calculating the power, the simplest method is to calculate the power required for raising the temperature from the specific heat of the ceramic plate 1 and the weight of the heating area. In addition, a correction coefficient due to the heating element pattern is taken into account. You may. Also,
A temperature rise test may be performed on a specific heating element pattern, a function of the temperature measurement position, input power, and temperature may be obtained in advance, and the input power may be calculated from this function. Then, the control unit 1 determines the applied voltage and time corresponding to the power calculated by the calculation unit 17.
5, and the control unit 15 supplies power to each heating element 2 based on the value.

FIG. 3 is a view showing another embodiment of the ceramic heater to which the present invention is applied. In the ceramic heater shown in this figure, heating elements 2a, 2b are formed on the bottom surface 1b of the ceramic plate 1, and these heating elements 2a, 2b are formed.
A metal coating layer 9 is formed on the outer periphery of b. An external terminal connection pin 6 is connected and fixed to these heating elements 2 a and 2 b via a metal coating layer 9, and a socket 18 is attached to the pin 6. The socket 18 is connected to the control unit 15 having a power source, and is otherwise configured in the same manner as the ceramic heater shown in FIG.

Next, as another embodiment of the ceramic base material of the present invention, in order to electrostatically adsorb an object to be adsorbed such as a silicon wafer on the chuck surface of the ceramic plate 1, the ceramic substrate 1 has There is one in which an electrostatic electrode is embedded to provide an electrostatic chuck function. That is, as shown in FIG. 6, together with the heating element 2 in the ceramic plate 1 or separately,
It is constructed by burying positive and negative electrostatic electrodes 11. The electrostatic electrode 11 is composed of a comb-shaped electrode composed of a positive electrode and a negative electrode. By applying a voltage to the electrode, an electrostatic field is generated to attract the silicon wafer 5 set on the ceramic plate 1. Used to support.

According to still another embodiment of the present invention, a heating element 2 and an electrostatic electrode 11
Alternatively, there is a ceramic substrate having a wafer prober function alone. As shown in FIGS. 7 (a) and 7 (b), the ceramic substrate provided with the wafer prober function has a guard electrode 12 and a ground electrode 13 embedded inside the ceramic plate 1 and the surface of the ceramic plate 1 as well. And a chuck top conductor layer 14 formed thereon. A silicon wafer 5 is placed on the chuck top conductor layer 14, a probe card with tester pins is pressed while heating, and a continuity test can be performed by applying a voltage to the chuck top conductor layer 14. It has become. In this wafer prober, the guard electrode 12
, The same voltage as that of the chuck top conductor layer 14 is applied to cancel the capacitance. The ground electrode 13 is provided for removing noise from the heating element 2.

The operation of this type of ceramic heater is shown in FIG.
Is the same as the ceramic heater shown in FIG.
The temperature of the heating element 2a is measured at regular intervals and stored in the storage unit 16, and a voltage value and the like controlled by the calculation unit 17 are calculated from the data.
By applying a predetermined voltage to 2b, the temperature of the entire heating surface 1a of the ceramic heater can be made uniform.

[0057]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to embodiments. Example 1-1 (Production of thermocouple) A metal wire made of a Pt-13% Rh alloy and having a cross-section diameter of 0.2 mm and a metal wire made of Pt and having a cross-section diameter of 0.2 mm were joined to each other for ^10-4 seconds. The two were joined by irradiating a pulsed carbon dioxide laser. Each metal wire has an inner diameter of 0.3 mm and a thickness of 0.02 m
m polyimide resin pipe 20 and insulated,
The thermocouple was 4 '. As shown in FIG. 4, the thermocouple 4 'is joined to the joint between the two types of metal wires 4a and 4b without forming a spherical melt 4c. Example 1-2 (Production of thermocouple) Two metal wires, a Ni / Cr wire and a Ni alloy wire, each having a cross-sectional diameter of 0.2 mm, were spot-welded by irradiating a pulse excimer laser for ^10-6 seconds. 0.3 m inside diameter for each metal wire
An alumina pipe 20 having a thickness of 0.02 mm and a heat of 0.02 m was fitted and insulated to form a thermocouple 4 '. As shown in FIG. 5, the thermocouple 4 'has a spherical melt 4c of about 0.2 mm formed at the joint between the metal wires 4a and 4b.

Example 2 Production of ceramic heater made of aluminum nitride (1) Aluminum nitride powder (average particle size: 1.1 μm) 100
Parts by weight, 4 parts by weight of yttria (average particle size: 0.4 μm),
A composition comprising 12 parts by weight of an acrylic binder and alcohol was spray-dried to prepare a granular powder. (2) Next, this granular powder was placed in a mold and formed into a flat plate to obtain a formed product (green). This green sheet is drilled to form a portion serving as a through hole 8 for inserting a support pin of a silicon wafer and a portion serving as a bottomed hole 3 for embedding a thermocouple (diameter: 1.1 mm, depth: 2 m)
m) was formed. (3) The processed green sheet is heated at 1800 ° C and pressure:
Hot pressing was performed at 200 kg / cm ² to obtain an aluminum nitride plate having a thickness of 3 mm. Next, a diameter of 12
An inch (300 mm) disk was cut out to obtain a ceramic plate (ceramic substrate) 1.

(4) A conductive paste was printed on the ceramic plate 1 obtained in (3) by screen printing. The printing pattern was a concentric pattern as shown in FIG. As this conductive paste, Solvest PS603D manufactured by Tokuri Kagaku Kenkyusho, which is used for forming through holes in a printed wiring board, was used. This conductive paste is a silver-lead paste. Lead oxide (5% by weight), zinc oxide (55% by weight), silica (10%
Wt.), Boron oxide (25 wt.%) And alumina (5 wt.
% By weight) of a metal oxide. The silver particles had an average particle size of 4.5 μm and were scaly.

(5) Next, the ceramic plate 1 on which the conductive paste is printed is heated and fired at 780 ° C. to sinter silver and lead in the paste and to bake the plate 1 with the heating element 2 Was formed. The silver-lead heating element 2 has a thickness of 5 μm.
m, the width was 2.4 mm, and the area resistivity was 7.7 mΩ / □. (6) Nickel sulfate 80 g / l, sodium hypophosphite 2
4 g / l, sodium acetate 12 g / l, boric acid 8 g /
The ceramic plate 1 prepared in the above (5) is immersed in an electroless nickel plating bath composed of an aqueous solution having a concentration of 6 g / l of ammonium chloride, and a thickness of 1 μm
Of the metal coating layer 9 (nickel layer). (7) A silver-lead solder paste (manufactured by Tanaka Kikinzoku) was printed by screen printing on a portion to which an external terminal for securing connection to a power supply was attached, to form a solder layer. Then, Kovar external terminal connection pins 6 were placed on the solder layer, and the pins 6 were attached to the surface of the heating element 2 by heating and tapping at 420 ° C.

(8) The thermocouple 4 of Example 1-1 for temperature control is inserted into the bottomed hole 3 and filled with a polyimide resin.
Curing was performed at 90 ° C. for 2 hours to obtain a ceramic heater.

Example 3 Production of Ceramic Heater Having Heating Element Inside (1) Aluminum Nitride Powder (manufactured by Tokuyama Co., Ltd. Average particle size:
1.1 μm), 4 parts by weight of yttria (average particle size: 0.4 μm), 11.5 parts by weight of an acrylic binder, 0.5 part by weight of a dispersant, and 53 parts by weight of alcohol composed of 1-butanol and ethanol were used to form a doctor blade. The green sheet having a thickness of 0.47 mm was obtained by molding. (2) Next, the green sheet was dried at 80 ° C. for 5 hours, and then punched with a diameter of 1.8 mm, 3.0 mm and 5.
Through-hole 8 for inserting 0 mm silicon wafer support pins 6
, And portions to be through holes 23 and 24 (connection pads) for connecting to the terminal pins 6.

(3) 100 parts by weight of tungsten carbide particles having an average particle diameter of 1 μm, 3.0 parts by weight of an acrylic binder, 3.5 parts by weight of an α-terpione solvent, and 0.3 of a dispersant
The conductive paste A was prepared by mixing parts by weight. A conductive paste B was prepared by mixing 100 parts by weight of tungsten carbide particles having an average particle diameter of 1 μm, 1.9 parts by weight of an acrylic binder, 3.7 parts by weight of an α-terpione solvent, and 0.2 parts by weight of a dispersant. The conductive paste A was printed on a green sheet by screen printing to form a conductive paste layer. The printing pattern was a concentric pattern as shown in FIG. Further, the conductive paste B was filled in the through holes 8 for through holes for connecting terminal pins. On the green sheet after the above processing, 37 green sheets on which the tungsten paste is not printed are printed on the upper side (heating surface), 13 sheets on the lower side, 130 ° C., 8
The layers were laminated at a pressure of 0 kg / cm ² .

(4) Next, the obtained laminate is placed in a nitrogen gas
Degreasing at 600 ° C for 5 hours, 1890 ° C, pressure 150kg
/ Cm ² for 3 hours to obtain an aluminum nitride plate having a thickness of 3 mm. This was cut out into a disk shape of 300 mm to obtain a ceramic heater having a heating element with a thickness of 6 μm and a width of 10 mm inside. (5) Next, the plate-like body obtained in (4) is polished with a diamond grindstone, a mask is placed, and the surface is subjected to blasting with glass beads to form a bottomed hole 3 (diameter) for a thermocouple on the surface. : 1.
2 mm, depth: 2.0 mm). (6) Further, a part of the through hole is cut out to form a recess, and a gold solder made of Ni-Au is used for the recess,
After heating and reflowing at 700 ° C., Kovar external terminal connection pins 6 were connected. The connection of the pins 6 is desirably a structure in which a tungsten support is supported at three points. This is because connection reliability can be ensured. (7) Next, the thermocouple 4 of Example 1-1 for temperature control was inserted into the bottomed hole 3 and silica sol was embedded therein.
For 1 hour to complete the manufacture of the ceramic heater.

Example 4 Electrostatic chuck (with ceramic heater) Basically the same as in Example 2, except that a semicircular portion is provided on the outer periphery of the green sheet, and a large number of portions extending in parallel and at equal intervals from the portion. An electrostatic electrode 11 in which a positive electrode and a negative electrode composed of linear portions are arranged in a comb-tooth shape is printed, and this green sheet is laminated with the green sheet on which the heating element 2 is printed.
Hot pressing was performed at 890 ° C. under a pressure of 150 kg / cm ² for 3 hours to obtain a 3 mm-thick aluminum nitride plate. This is cut out into a 300 mm disk, and a 6 μm thick
An electrostatic chuck with a heater having a heating element having a width of 10 mm and a comb-shaped electrostatic electrode 11 was prepared.

Example 5 Wafer prober (with ceramic heater) (1) Aluminum nitride powder (manufactured by Tokuyama, average particle diameter 1.1)
μm) 100 parts by weight, yttria (yttrium oxide, average particle size 0.4 μm) 4 parts by weight, acrylic binder
A composition obtained by mixing 11.5 parts by weight, 0.5 part by weight of a dispersant, and 53% by weight of alcohol composed of 1-butanol and ethanol was formed with a doctor blade to a thickness of 0.47 mm.
Green sheet was obtained. (2) After the green sheet was dried at 80 ° C. for 5 hours, a hole for a through hole for connecting the heating element 2 and the external terminal connection pin 6 was provided by punching. (3) Tungsten carbide particles 1 having an average particle diameter of 1 μm
A conductive paste A was prepared by mixing 00 parts by weight, 3.0 parts by weight of an acrylic binder, 3.5 parts by weight of an α-terpione solvent, and 0.3 parts by weight of a dispersant. Further, 100 parts by weight of tungsten particles having an average particle diameter of 3 μm, an acrylic binder 1.
9 parts by weight, 3.7 parts by weight of α-terpione solvent, dispersant
The conductive paste B was prepared by mixing 0.2 parts by weight. The printed material for the guard electrode 12 and the printed material for the ground electrode 13 were printed in a grid pattern on the green sheet by screen printing on the conductive paste A to form an electrode pattern. Further, as shown in FIG. 1, the heating element 2 was printed on the back surface of the green sheet in a concentric pattern. In addition, the conductive paste B was filled in through-holes for connecting to the terminal pins 6. Then, 50 green sheets that have been printed and green sheets that have not been printed are stacked at 130 ° C.
^They were integrated under a pressure of 80 kg / cm ² .

(4) The laminate was degreased in nitrogen gas at 600 ° C. for 5 hours and hot-pressed at 1890 ° C. under a pressure of 150 kg / cm ² for 3 hours to obtain an aluminum nitride plate having a thickness of 3 mm. This was cut into a circular shape having a diameter of 230 mm to obtain a ceramic plate. The size of the through hole was 0.2 mm in diameter and 0.2 mm in depth. The guard electrode 12 and the ground electrode 13 have a thickness of 6 μm,
Is 0.7 mm from the wafer mounting surface, the formation position of the ground electrode 13 is 1.4 mm, and the position of the heating element 2 is 2.
8 mm.

(5) The plate obtained in (4) is polished with a diamond grindstone, a mask is placed, and the surface is subjected to blasting with glass beads to form a bottomed hole 3 for a thermocouple 4 and a wafer. A groove 19 for suction (width 0.5 mm, depth 0.5 mm) was provided (FIG. 7b). (6) A film composed of three layers of titanium, molybdenum and nickel was formed on the surface where the groove 19 was formed by sputtering. As a device for sputtering, SV-4540 manufactured by Japan Vacuum Engineering Co., Ltd. was used. Conditions are pressure 0.6
The time was 30 seconds to 1 minute at a temperature of Pa, a temperature of 100 ° C., and a power of 200 W, and was adjusted for each metal. From the image of the X-ray fluorescence spectrometer, the obtained three-layered film showed that titanium was 0.5 μm,
Molybdenum had a thickness of 4 μm and nickel had a thickness of 1.5 μm.

(7) Nickel sulfate 30 g / l, boric acid 30
g / l, ammonium chloride 30 g / l, Rochelle salt 6
The ceramic substrate 1 obtained in (6) was immersed in an electroless nickel plating bath composed of an aqueous solution having a concentration of 0 g / l, and a thickness of 7 μm and a boron content of 1 were formed on the surface of the film on the groove 19 side. Weight percent or less of nickel is deposited and laminated,
Anneal for 3 hours at ° C. Furthermore, on the surface, potassium gold cyanide 2 g / l and ammonium chloride 75 g /
l, sodium citrate 50g / l and sodium hypophosphite 10g / l in an electroless gold plating solution at 93 ° C.
Immersion for about 1 minute to form a gold plating layer having a thickness of 1 m on the nickel plating layer 15, thereby forming the chuck top conductor layer 1
4 was formed.

(8) The air suction hole 2 that passes through the groove 19 to the back surface
2 was drilled, and holes for exposing the through holes 23 and 24 were provided. Using a gold solder made of a Ni—Au alloy (Au81.5, Ni18.4, impurity 0.1), the holes were heated and reflowed at 970 ° C. to connect the Kovar terminal pins 6. Was inserted into the bottomed hole and sealed with a polyimide resin to form a wafer prober.

Example 6 The same as Example 1 except that no bottomed hole was formed and the thermocouple 4
As shown in FIG. 3, was fixed to the surface of the ceramic plate 1 (on the side where the heating element was formed) with an inorganic adhesive (trade name: Aron Ceramic manufactured by Toa Gosei).

Embodiment 7 Embodiment 7 is the same as Embodiment 1 except that Embodiment 1 shown in FIG.
Two thermocouples were used.

Comparative Example As in Example 1, the thermocouple used was spot-welded thermocouple 4 'of Example 1-2 as shown in FIG. The thickness of the joint 4c was 0.8 mm.

300 m diameter when heated to 200 ° C.
The difference between the maximum temperature and the minimum temperature of the m-shaped disc-shaped ceramic plate was examined for Examples 2 to 7 and Comparative Example. Table 1 shows the results.

[Table 1]

[0075]

As described above, according to the ceramic substrate for a semiconductor manufacturing apparatus of the present invention, when it is constituted as a ceramic heater, it is possible to accurately measure the temperature of the object to be heated. By adjusting the heating state of the heating element based on the measurement result, the entire object to be heated such as a silicon wafer can be uniformly heated. Further, when this is configured as an electrostatic chuck, unevenness in chucking force due to uneven temperature is eliminated, and when configured as a wafer prober, an error in a conduction test due to uneven temperature is obtained.

[Brief description of the drawings]

FIG. 1 is a bottom view schematically showing an example configured as a ceramic heater.

2A is a block diagram schematically showing a part of a case where the present invention is a ceramic heater, and FIG. 2B is a partially enlarged sectional view thereof.

FIG. 3A is a block diagram schematically illustrating another example in which the present invention is configured as a ceramic heater.

FIG. 4 is a schematic diagram of a thermocouple of the present invention.

FIG. 5 is a schematic view of a conventional thermocouple.

FIG. 6 is a schematic diagram of a ceramic substrate having an electrostatic chuck function.

FIG. 7 is a schematic view of a ceramic substrate having a wafer prober function.

FIG. 8 is a block diagram schematically showing still another example when the present invention is a ceramic heater.

[Explanation of symbols]

 Reference Signs List 1 ceramic substrate 1a heating surface 1b bottom surface 2 heating element 3 bottomed hole 4 thermocouple 5 silicon wafer 6 terminal pin 7 support pin 8 through hole 9 metal coating layer 10, 23, 24 through hole 11 electrostatic electrode 12 guard electrode 13 ground Electrode 14 Chuck top electrode 15 Control unit 16 Storage unit 17 Operation unit 18 Socket 19 Groove 22 Air suction hole

Claims (7)

[Claims] In a thermocouple formed by joining two different types of metal wires, the size of the joining portion of each of the metal wires is
A thermocouple for a ceramic substrate, wherein the thermocouple has a size equal to or larger than the strand diameter of each metal wire, but not larger than 0.5 mm. 2. A temperature control means is provided on the surface or inside of a ceramic plate, and a different
It is characterized in that a thermocouple that joins two types of metal wires and that the size of the joining area is equal to or larger than the wire diameter of each metal wire, but is 0.5 mm or less is provided. Ceramic substrate for semiconductor manufacturing equipment. 3. The ceramic substrate for a semiconductor manufacturing apparatus according to claim 2, wherein a ceramic heater function is provided. 4. The ceramic substrate according to claim 2, wherein an electrostatic chuck function is provided by embedding an electrostatic electrode inside the ceramic plate. 5. The semiconductor device according to claim 1, wherein a guard electrode and a ground electrode are buried inside the ceramic plate, and a chuck top conductor layer is formed on a semiconductor wafer mounting surface on the surface of the ceramic plate to provide a wafer prober function. The ceramic substrate for a semiconductor manufacturing apparatus according to any one of claims 2 to 4, wherein 6. The ceramic substrate for a semiconductor manufacturing apparatus according to claim 2, wherein said thermocouple is embedded in a ceramic plate. 7. The ceramic substrate according to claim 2, wherein said thermocouple is attached to a surface of a ceramic plate.