JP2002359281A - Ceramic heater and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive ceramic heater which can hold a wafer and uniformly heat the wafer. SOLUTION: On thin green sheets 13 and 15, a heater pattern 14 and filmy electrostatic attraction patterns 16P and 16N are formed by screen printing method, and sandwiched between a ceramic base body 11 of high purity and a ceramic suction surface body 18 and then baked in one body for constituting a thick ceramic heater 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor manufacturing apparatus and, more particularly, to a chemical vapor deposition (CVD Ch.
The present invention relates to a ceramic heater suitable for holding a wafer while heating it when performing an emical vaper diposition), plasma etching, sputtering or the like.

[0002]

2. Description of the Related Art In semiconductor manufacturing apparatuses such as LSIs, electrostatic chucking means using Coulomb force or Johnson Rahbeck effect is often used to hold a wafer. This electrostatic suction means not only has a function of simply holding the wafer, but also has a function of maintaining the temperature of the wafer uniformly in a harsh environment, a function of not contaminating the inside of a chamber, and a function under a severe atmosphere. A function that can withstand use is also required. Japanese Patent No. 252471 discloses this kind of wafer holding device and heating device,
JP-A-2000-348853, JP-B-7-507
No. 36 is disclosed.

In the first patent publication, the metal base plate 1
An elastic insulator 3 is interposed between the sintered ceramic plate 6 and the sintered ceramic plate 6 to relieve the thermal stress applied to the sintered ceramic plate 6 by the elastic deformation thereof (see FIG. 1 of the publication).

[0004] In the second publication, a heater element 8 made of silicon carbide containing no additive is interposed between a base 2 made of aluminum nitride and a cover plate 3 made of aluminum nitride. (See FIG. 1 of the official gazette). By combining materials having similar coefficients of thermal expansion, thermal shock is reduced, durability is improved, and contamination resistance is improved.

In the third publication, the substrate 2A made of silicon nitride, aluminum nitride, sylon, or the like having a coefficient of thermal expansion similar to that of the wafer to be processed and the dielectric layer 4A are used as main elements. A film electrode 5A that functions as an electrostatic chucker is disposed between the substrate 2A and the dielectric layer 4A.
A structure in which a resistance heating element 3 made of a tungsten wire is embedded therein is disclosed (see FIG. 3 of the official gazette). Since the base 2A and the dielectric layer 4A are made of the above-mentioned ceramics, they can withstand high temperatures and can be used in a thermal CVD apparatus that reaches 500 ° C. In addition, the surface of the dielectric layer 4A is polished to increase the flatness, thereby increasing the adhesion when the wafer is sucked, and enabling uniform heating over the entire surface of the wafer.

[0006]

However, since the elastic insulator film 3 made of silicon rubber expands and contracts in accordance with a change in temperature, the elastic insulator film 3 described in the first patent publication has a long life. However, there is a problem that durability is poor. Further, since the thicknesses of the plates 6, 5, 7, and 3 interposed from the metal base plate 1 to the wafer 11 are thin, it is presumed that they cannot withstand high temperatures.

[0007] The product disclosed in the above-mentioned second publication has excellent functions as a product, but has complicated shapes such as a substrate 1 made of aluminum nitride, a cover plate 3 and a heater element 8 made of silicon carbide. Must be manufactured by the hot press method. Therefore, there is a problem that the cost is increased.

[0008] Further, although the product disclosed in the third publication has a flange portion 4b and thus exhibits more excellent functions as a product, the spiral resistance heating element 3 made of tungsten is embedded. The base 2A made of silicon nitride, the ceramic dielectric layer 4A, and the like must be manufactured by a hot press method. Therefore, there is a problem that the cost is increased.

A ceramic heater used in a semiconductor manufacturing apparatus, especially a CVD apparatus, is required to have a function of uniformly heating a wafer. Therefore, the in-plane temperature distribution of the heating surface of the ceramic heater is ± 5% or less (preferably ± 1% or less).
Need to be suppressed. One method for keeping the in-plane temperature distribution small is to increase the thickness of the entire ceramic heater to increase the heat capacity and make the in-plane temperature distribution uniform. In the second and third publications, the thickness of the bases 1 and 2A is set to 15 mm or more.

In order to produce such a thick ceramic product, a hot pressing method or a hot isostatic pressing method is used. Since this method is a method of baking while applying a uniform pressure, the manufacturing apparatus becomes large-sized, and this is a major factor of cost increase. Also. In the hot press method, since the conductive portion cannot be formed by the screen printing method, the cost is extremely increased if the pattern of the resistance heating element or the film-like electrostatic attraction pattern built in the ceramic heater is complicated.
On the other hand, in the sheet lamination method in which screen printing can be introduced, 5
Only those having a thickness of less than mm can be manufactured.

Further, the ceramic heater used in the CVD apparatus cannot be used continuously for the life of the semiconductor manufacturing apparatus, but is a consumable that must be replaced with a new one every few months due to the severe atmospheric conditions. For this reason, cost reduction is particularly required for this type of ceramic heater.

Accordingly, an object of the present invention is to provide an inexpensive ceramic heater capable of holding a wafer and uniformly heating the wafer. It is another object of the present invention to provide a method of manufacturing the same.

[0013]

Means for achieving the above object will be described with reference to FIG. 1 as an example.
The invention according to claim 1 of the present invention provides a ceramic heater body (10) made of alumina, mullite, magnesia, aluminum nitride, silicon nitride, or the like, and a resistance heating element embedded inside the ceramic heater body (10). And a suction surface 18 capable of sucking a wafer as a workpiece is formed on one surface of the ceramic heater body (10).
The ceramic heater body (10) has a main component composition of 9
It is characterized by having a multilayer structure of layers 11 and 17 having a high purity of more than 5% and layers 13 and 15 of a relatively low purity having a main component composition of 95% or less.

When formed in such a manner, it includes a binder,
A layer 13 having a composition of a main component of 95% or less and a relatively low purity,
15 is formed as a ceramic green sheet, and the functional portions 14, 16P and 16N of the resistance heating element 14 can be formed thereon by a screen printing method. The high-purity layers 11, 17 having a composition of the main component exceeding 95% can be easily formed by an extrusion method or a press method. Then, the two parts are laminated and fired at normal pressure to form the functional part 1.
It is possible to manufacture the ceramic heater 10 incorporating 4, 16P, 16N. In other words, the ceramic heater 10 having a large thickness, most of which is made of a high-purity layer, can be provided at extremely low cost because of the use of the screen printing method and the firing at normal pressure. Since the ceramic heater 10 has a large thickness, the temperature distribution is made uniform, and the in-plane temperature distribution of the suction surface 18 serving as a heating surface can be suppressed to a small value. Furthermore, the high-purity layers 11, 1
7 occupies the majority, so that contamination (contamination) of the chamber from the ceramic heater 10 can be reduced.

Here, as described in the second aspect of the present invention, the layer forming the suction surface 18 of the ceramic heater body (10) may be constituted by the high-purity layer 17. When formed in this manner, since the suction surface 18 in contact with the wafer is composed of the high-purity ceramic layer 17, the wafer is not contaminated by the adhesion of silica or the like from the low-purity ceramic layers 13 and 15, and the ceramic that is resistant to contamination. A heater 10 can be provided.

Here, as in the third aspect of the present invention, each of the layers 11, 1 constituting the ceramic heater body (10).
3, 15, 17 can be characterized by comprising alumina. When formed in this manner, a ceramic heater can be provided at a lower cost than when formed from a non-oxide ceramic such as silicon nitride or aluminum nitride. Alumina is sufficient for heat resistance.

Here, as in the fourth aspect of the present invention, the suction surface 1 inside the ceramic heater body (10).
8, a film-like electrostatic attraction pattern 16 capable of applying a voltage
P and 16N are formed. When formed in this manner, not only the attraction force between the attraction surface 18 of the ceramic heater 10 and the surface of the wafer, but also a high voltage is applied to the film-like electrostatic attraction patterns 16P and 16N, so that the attraction surface 18 A suction force due to Coulomb force or a suction force due to the Johnson-Rahbek effect acts between the wafer and the wafer, and the film-like electrostatic suction patterns 16P, 16P
Since the distance between N and the wafer is short, the wafer can be strongly attracted to the ceramic heater 10 accordingly.

Here, the film-like electrostatic attraction patterns 16P and 16N are composed of a positive electrode and a negative electrode, and the film-like electrostatic attraction pattern 16P of the positive electrode and the film of the negative electrode are provided. The shape of the electrostatic attraction pattern 16 </ b> N may be different. If the areas of the positive electrode 16P and the negative electrode 16N are formed differently as described above, it was possible to further increase the suction force of the wafer, although this is an experimental result.

Here, as in the sixth aspect of the present invention, the resistance heating element 14 or the film-like electrostatic attraction pattern 16 is used.
P and 16N can be characterized in that they are formed in the layers 13, 15 having a relatively low purity. When formed in this manner, the relatively low-purity layers 13 and 15 can be layers containing not only the main component but also a binder. Therefore, functional elements such as the resistance heating element 14 or the film-like electrostatic attraction patterns 16P and 16N can be formed by the screen printing method. Therefore, the ceramic heater 1 having a complicated resistance heating element (heater pattern) 14
0 can be manufactured inexpensively.

Here, as in the invention according to claim 7, the ceramic heater body (10) is plate-shaped and has a thickness of 5 mm or more and 30 mm or less. When the plate thickness is 5 mm or less, the heat capacity of the ceramic heater body becomes insufficient, and it becomes difficult to suppress the in-plane temperature distribution of the suction surface 18 of the ceramic heater 10 to a small value.
If the plate thickness is 30 mm or more, the binder in the central portion is not easily burned out when firing the laminated product at normal pressure, and it is not easy to escape to the outside, and a part of the binder is in the ceramic heater body (10). May be left behind.
This is not preferred. Therefore, the thickness of the ceramic heater body (10) is preferably 5 mm or more and 30 mm or less.

Here, as in the present invention, high-purity ceramic plates 11 and 17 are formed by extrusion or pressing using a high-purity ceramic powder having a main component composition of 92% or more. Process and composition of main component is 9
A step of forming ceramic green sheets 13 and 15 using a relatively low-purity ceramic powder containing a binder of 5% or less, and a resistive heating element 14 or film-like electrostatic attraction patterns 16P and 16N on the green sheets 13 and 15; And a step of laminating the high-purity ceramic plates 11 and 17 and the green sheet on which the resistance heating elements 14 or the film-like electrostatic attraction patterns 16P and 16N are formed, and bonding them with a ceramic paste. And a step of integrally firing the laminated and bonded ceramic plates 11 and 17 and the green sheets 13 and 15.

The method claimed in claim 8 is the claim of claim 1 described from the aspect of the method, and has the same operation and effect as described in paragraph [0014].

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an exploded perspective view illustrating a manufacturing process of the ceramic heater 10 according to the first embodiment. The ceramic heater 10 is mainly composed of a ceramic base 11, a first green sheet 13, a second green sheet 15, and a ceramic adsorption face 17 from the bottom of the drawing. Each of the members 11, 13, 15, and 17 has a disk shape, and has a diameter of, for example, about 205 mm for mounting an 8-inch wafer. Plate thickness is 2 in total
The thickness is selected to be about 0 mm.

The ceramic substrate 11 is made by press-molding a high-purity ceramic powder. For example, it is formed by pressing a 99.9% or higher-purity alumina powder. At this time, four through holes 11A, 11B,
11C and 11D are formed in advance. Ceramic adsorption face body 1
7 is also formed by pressing high-purity alumina powder. The pressure at the time of press working is as follows:
Of the green sheets 13 and 15 are adjusted.

The green sheets 13 and 15 are produced as follows. First, magnesium oxide Ca was added to alumina powder.
O was mixed with 1 wt% (weight ratio, the same applies hereinafter) and ₄ wt% of silicon oxide (silica) SiO ₄ , and mixed with a ball mill.
After wet grinding for ~ 80 hours, dehydrate and dry. 3 wt% of isobutyl methacrylate, 3 wt% of butyl ester, 1 wt% of nitrocellulose,
Dioctyl phthalate is added in an amount of 0.5 wt%, and trichlorethylene and n-butanol are further added as a solvent and mixed with a ball mill to form a fluid slurry.
(Hereinafter, this slurry is referred to as alumina slurry). After deaeration of the alumina slurry under reduced pressure, the alumina slurry is poured into a flat plate and cooled slowly, and the solvent is dispersed to form an alumina green sheet having a thickness of 0.8 mm. Molybdenum Mo, titanium Ti
Etc. may be added.

The metallized ink to be printed on the green sheet is made into a metallized ink by mixing tungsten (W) powder in the same manner as in the preparation of the alumina slurry. A spiral heater pattern (resistance heating element) 14 is formed on the first green sheet 13 having a thickness of 0.8 mm by using a normal screen printing method. A second green sheet 15 having a thickness of 0.8 mm is placed thereon. Two film-like electrostatic attraction patterns 16P and 16N are formed on the second green sheet 15 using a normal screen printing method. Further, a third green sheet (not shown) having a thickness of 0.8 mm is placed thereon and thermocompression-bonded to form one sheet. At this time, each of the through holes 13A, 13B, 13C, 13D, 15C, 1
5D is filled with metallized ink. The thermocompression-bonded sheet is formed into a disk shape having a diameter of 205 mm by machining such as machining.

The thermocompression-bonded thin sheets 13 and 15 are sandwiched and adhered between the ceramic substrate 11 and the ceramic adsorbing face member 17 to be integrated. That is, the alumina slurry is applied to the upper surface of the ceramic base 11 to form a paste surface 12, and the thermocompression bonded sheets 13 and 15 are bonded. Alumina slurry is also applied to the upper surfaces of the sheets 13 and 15, and the ceramic adsorption surface body 17 is bonded. In addition, each through hole 11A, 11B, 11C, 11D is filled with metal tin ink. Next, the joined body is integrally fired at 1400 to 1600 ° C. in a reducing atmosphere such as hydrogen gas. Then, the fired ceramic adsorption surface body 1
The surface of the wafer 7 is polished to a flat surface having a flatness of 30 μm or less (preferably 10 μm or less) to form the suction surface 18 of the wafer.

FIG. 2 is a perspective view of the ceramic heater 10 formed in this manner as viewed from below. The terminal portions formed by firing the metallized ink filled in the through holes 11A, 11B, 11C, and 11D are plated with nickel, and furthermore, nickel pins are brazed and the terminals 11 are formed.
A ', 11B', 11C ', and 11D'. Terminal 11
A 'and 11B' are through holes 11A and 13A, respectively.
A and the heater pattern 14 are connected to the outer end and the center end via the through holes 11B and 13B. Terminal 11
C 'and 11D' are through holes 11C and 13 respectively.
It is electrically connected to the film-like electrostatic attraction pattern 16P or 16N via C and through holes 11D and 13D, respectively.

The ceramic body occupying the main body of the ceramic heater 10 thus formed has a high-purity layer (ceramic base 11, ceramic adsorbing face 17) having an alumina composition of 99.9% and an alumina composition. It has a multilayer structure with relatively low-purity layers (the first and second green sheets 13, 15 and the third green sheet) having a composition of about 92%. The thickness of the low-purity layer is about 2.4 mm, and the total thickness of the high-purity layer exceeds 15 mm.

The operation based on the above configuration will be described. When a voltage is applied to the terminals 11A 'and 11B', a current flows through the spiral heater pattern 14, and the ceramic heater of the ceramic heater 10 is heated, for example, the suction surface 18 is heated to 500 ° C. Also, terminal 11
By applying a high voltage to C 'and 11D', for example, +1 kV to terminal 11C 'and -1 kV to terminal 11D', the voltage at terminal 11C 'is reduced to through-hole 13C,
+ 1k on the film-like electrostatic attraction pattern 16P via 15C
V is applied, and the voltage at the terminal 11D 'is
To the film-like electrostatic attraction pattern 16N via D and 15D-
1 kV is applied. The silicon wafer to be processed is placed on the suction surface 18 of the ceramic heater 10 and sucked. At this time, since a high voltage is applied to the film-like electrostatic attraction patterns 16P and 16N near the attraction surface 18, electric charges are induced on the silicon wafer as a dielectric, and the silicon wafer is brought to the attraction surface 18 by Coulomb force. It is sucked.

The advantages of this embodiment will be described. Since the thickness of the ceramic heater body (10) is as thick as 15 mm or more, the temperature distribution on the suction surface 18 is made uniform, and the in-plane temperature distribution of the suction surface 18 for sucking the wafer can be suppressed to a small value. Further, since the layers 11 and 17 having high ceramic purity occupy most of the surface area of the ceramic heater 10, contamination from the ceramic heater 10 can be suppressed to a small value. Further, since the purity of the ceramic suction surface body 17 which is a layer constituting the suction surface 18 is high, the suction surface 1
The silicon wafer contacting No. 8 is not contaminated by the adhesion of silica or the like, and is resistant to contamination. Furthermore, each of the layers 11, which constitute the ceramic heater body (10),
Since the members 13, 15, 17 are made of alumina, the ceramic heater 10 having sufficient heat resistance can be provided at low cost.

In this embodiment, the positive electrode 16P and the negative electrode 16N of the film-like electrostatic attraction patterns 16P and 16N have the same area, but the positive film-like electrostatic attraction pattern 16P and the negative electrode film The area of the electrostatic attracting pattern 16N may be made to differ greatly. In this case,
Although experimentally, the suction force of the silicon wafer could be increased.

In the present embodiment, alumina was used as the ceramic, but other various ceramics such as, for example,
Magnesia, mullite or the like may be used.

FIG. 3 is an exploded perspective view for explaining a manufacturing process of the ceramic heater 20 according to the second embodiment. The difference from the ceramic heater 10 described with reference to FIG. 1 is that a heater pattern serving as a resistance heating element is formed not in one layer but in three layers. 1 are given the same reference numerals to facilitate understanding. The ceramic heater 20 includes a ceramic base 11, a first green sheet 21 for a first heater pattern 22, and a second
Second green sheet 23 for the heater pattern 24,
Third green sheet 2 for third heater pattern 26
5, a fourth green sheet 15 for the suction patterns 16P and 16N, and a ceramic suction face 17;

The ceramic base 11 and the ceramic adsorbing face 17 are formed by press-molding high-purity alumina powder in the same manner as described in the paragraph [0024]. The method of forming the first to fourth green sheets 21, 23, 25, and 15 is the same as that described in paragraph [0025]. Heater patterns 22, 23, 25 and film-like electrostatic attraction patterns 16P, 16N are formed on the green sheets 21, 23, 25, and 15, respectively, and thermocompression-bonded. Bonding at 17 and bonding with alumina slurry and firing integrally are the same as described in paragraphs [0026] and [0027].

The first, second and third green sheets 21
Heater patterns 22, 24, and 26 having different shapes are formed on the electrodes 23, 25 by screen printing using tungsten (W) metallized ink. Although each of the heater patterns 22, 24, and 26 draws a different pattern, the through holes 21 at the outer end of the green sheet are formed.
A single-stroke pattern is formed starting from A, 23A, 25A and reaching the center through holes 21B, 23B, 25B. Through holes 21A and 23 at outer end
A and 25A are provided in the through-holes 11A on the outside of the ceramic base 11 and central through-holes 21B, 23B and 25B.
Is in the through hole 11B at the center of the ceramic base 11,
Each of the three heater patterns 22, 24, and 2 is connected by being filled with the metallized ink.
6 will be electrically connected in parallel.

The three green sheets 21, 23, 23
Each heater pattern 22, 24, 26 on the 25 layers is
Except for the vicinity of the starting point and the end point, the suction surface 18 is formed so as not to overlap when viewed from above. FIG. 4 is a virtual plan view showing a state in which each of the heater patterns 22, 24, 26 is seen through from above the suction surface 18. Heater pattern 2
The hatches 2, 24, and 26 are differently hatched so that they can be identified. However, since the heater pattern is difficult to see, please be forgiven. The heater pattern starting from the through hole 11A near the outer edge of the ceramic base 11 includes a heater pattern 26 on the outermost periphery (on the third green sheet 25) and a heater pattern 24 on the inner side.
It branches into three heater patterns (on the second green sheet 23) and the innermost heater pattern 22 (on the first green sheet). Each heater pattern 22, 24,
26 gather around the center of the ceramic base 11 in a unique spiral pattern as shown in FIG. The heater patterns 22, 24, 26 gathered near the center become one at the center through hole 11B. Through hole 11C, 11
D is for connecting to the film-like electrostatic attraction patterns 16P and 16N.

Here, three heater patterns 22, 2
Note that the four heaters 4 and 26 are electrically connected in parallel and that the entire area of the suction surface 18 is almost covered by the three heater patterns 22, 24 and 26.

The advantages of this embodiment will be described. 3
Since the heater patterns 22, 24, 26 of the heater layers (green sheets 21, 23, 25) are electrically connected in parallel, the heat generation of each heater pattern 22, 24, 26 is leveled, and Only the heater pattern does not overheat. This is because if the tungsten (W) metallization constituting the heater pattern has a positive temperature resistance coefficient, if it is connected in series, if the temperature of some heater patterns rises, the resistance increases in proportion to the rise in temperature. Since the value R increases and the amount of generated heat is proportional to I ² R, the amount of generated heat further increases, and only some of the heater patterns are overheated. In the present embodiment, since the heater patterns are connected in parallel, such a situation cannot occur. When the temperature of some heater patterns rises, the resistance value R increases in proportion to the rise in temperature, and the amount of heat generated decreases because the current flowing through the heater patterns decreases. For this reason, the calorific value of each heater pattern 22, 24, 26 is leveled, and as a result, the temperature distribution of the suction surface 18 is made uniform.

Further, the three heater patterns 22 and 2
Since the entire area of the suction surface 18 is almost completely covered by the suction surfaces 4 and 26, a heater pattern is necessarily provided immediately below the suction surface 18 and the temperature distribution of the suction surface 18 can be more easily made uniform. .

Although it is not impossible to consider a pattern in which a single heater pattern covers the area directly below the suction surface 18, a heater pattern metallized by screen printing has an area equal to or more than １ ／ of the area of the green sheet. Creating it involves technical difficulties. Therefore, it is practically excellent to divide the heater pattern into three parts and form the heater patterns on different green sheets as in the present embodiment.

Further, as shown in FIG. 3, the present embodiment is provided with the film-like electrostatic attraction patterns 16P and 16N. Therefore, as described in the paragraph [0030], both patterns 16P and 16N are provided. By applying a high voltage, the silicon wafer placed on the suction surface 18 can be sucked. Furthermore, each green sheet 21, 23, 25, 15
Is made of alumina, it is possible to provide a ceramic heater 20 having sufficient heat resistance at low cost.

FIG. 5 is a sectional view showing a ceramic heater 30 according to the third embodiment, and FIG. 6 is a view (plan view) taken in the direction of the arrow X in FIG. This ceramic heater 30
Ceramic heater body (ceramic heater) shown in FIG.
10 is supported by a cylindrical support 32 and integrated. As described with reference to FIG. 1, the ceramic heater body 10 includes a heater pattern (resistance heating element) 14 and film-like electrostatic attraction patterns 16P and 16N inside. A ceramic plate 33 made of aluminum nitride having high thermal conductivity is closely mounted on the disk-shaped ceramic heater body 10. The peripheral edge of the disk-shaped ceramic heater body 10 is supported by a flange 32A of a cylindrical support 32. The cylindrical support 32 is made of alumina ceramic. The support 32 has its bottom fixed to the mounting portion 31 of the semiconductor manufacturing apparatus. The ceramic heater 30 is surrounded by a housing 51 of a semiconductor manufacturing apparatus and forms a high-vacuum chamber 50. A space surrounded by a cylindrical portion of a support 32 below the ceramic heater body 10 has an air insulation layer 40. Make up.

FIG. 6 is a plan view of the ceramic heater 30. A notch 35 for positioning protruding in the inner circumferential direction is integrally formed on the support 32, and a concave portion corresponding to the notch 35 is formed on the ceramic heater body 10 and the ceramic plate 33. In addition, the ceramic plate 33 is accurately positioned.

There are two methods for manufacturing such a ceramic heater 30 in which the support 32 and the ceramic heater body 10 are integrated. The first method is a method in which the ceramic heater body 10 and the support body 32 before firing are joined with a ceramic slurry and fired integrally. The second method is a method in which the support 32 and the ceramic heater body 10 are separately fired, and the fired ones are polished to ensure dimensional accuracy and combined.

The first method will be described. The intermediate products of the ceramic heater body 10 are paragraph numbers [0024] and [00].
25] and [0026]. The support 32 was prepared by mixing 1 wt% of magnesium oxide (CaO) (weight ratio, the same applies hereinafter) and ₄ wt% of silicon oxide (silica) SiO ₄ with alumina powder, and mixing them with a ball mill.
After wet pulverization for 0 to 80 hours, dehydration drying is performed. This powder is formed into a cylindrical shape by press working. Next, the alumina slurry described in the paragraph number [0025] is applied between the ceramic heater body 10 (sheet-formed product) and the support body 32 (press-formed product) and adhered. Then, the bonded pieces are integrally fired at 1400 to 1600 ° C. in a reducing atmosphere. The fired product is polished so that the flatness of the suction surface 18 of the ceramic heater body 10 is 30 μm or less. Next, the through holes 11A, 11B, 1
Nickel plating is applied to the terminal portion formed by firing the metallized ink filled in 1C and 11D, and further, a nickel pin is brazed and the terminals 11A ', 11B', 11
C 'and 11D'. Finally, as shown in FIG. 5, so that the temperature distribution on the mounting surface of the silicon wafer becomes uniform,
A ceramic plate 33 made of aluminum nitride is placed.

Next, the second method will be described. The ceramic heater body 10 has paragraph numbers [0024], [0025],
[0026] It is manufactured by firing as described in [0027]. Then, the outer cylinder of the fired ceramic heater body 10 is polished to secure the outer dimension accuracy. Further, at this time, a concave portion that fits into the positioning notch 35 is also provided by polishing. As the support 32, a cylindrical press-formed product is produced as described in paragraph [0046]. This cylindrical press-formed product is fired in the atmosphere to obtain a cylindrical ceramic molded body. The portion of the fired ceramic molded body on which the ceramic heater body 10 is to be mounted (in the vicinity of the flange portion 32A) is polished for the inner cylinder to secure the dimensional accuracy of the inner diameter. At this time, the projection of the notch 35 for positioning is also provided by polishing. And a notch 35 for positioning.
The ceramic heater body 10 and the support 3
2 is integrated.

For the purpose of ensuring uniform temperature distribution on the adsorption surface 18 of the ceramic heater body 10, a ceramic plate 33 made of aluminum nitride having high thermal conductivity is placed on the upper or lower surface of the ceramic heater body 10. At this time, similarly to the ceramic heater 10, a concave portion that engages with the notch 35 for positioning is provided in the ceramic plate 33 made of aluminum nitride by polishing. In order to make the temperature distribution even more uniform, it is preferable that the contact surface between the suction surface 18 of the ceramic heater body 10 and the ceramic plate 33 is polished to improve flatness and increase the contact ratio.

In the above example, the cylindrical support 32 is formed of a press-formed product of alumina. However, the main body of the support is formed of a metal, and a ceramic such as alumina is sprayed on the metal to form a surface. An insulator may be used.

The advantages of this embodiment will be described. Since the ceramic heater body 10 is supported by the cylindrical support 32, the temperature of the ceramic heater body
Therefore, the distance from the suction surface 18 to the mounting portion 31 of the low-temperature device can be increased, and the temperature gradient in the thickness direction of the ceramic heater body 10 can be reduced. For this reason, the thermal stress due to the difference in thermal expansion can be greatly reduced, and the reliability of the ceramic heater 30 has been greatly improved.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view illustrating a manufacturing process of a ceramic heater according to a first embodiment.

FIG. 2 is a perspective view of the ceramic heater according to the first embodiment as viewed from below.

FIG. 3 is an exploded perspective view illustrating a manufacturing process of a ceramic heater according to a second embodiment.

FIG. 4 is a virtual plan view showing a state where each heater pattern is seen through from above the suction surface.

FIG. 5 is a sectional view showing a ceramic heater according to a third embodiment.

FIG. 6 is a plan view as seen in the direction of the arrow X in FIG. 5;

[Explanation of symbols]

 Reference Signs List 10 ceramic heater (ceramic heater body) 11 ceramic base 13 first green sheet 14 heater pattern (resistance heating element) 15 second green sheet 16P, 16N film-like electrostatic attraction pattern 17 ceramic attraction surface 18 attraction surface 21 first Green sheet 22 first heater pattern 23 second green sheet 24 second heater pattern 25 third green sheet 26 third heater pattern 31 mounting part 32 support 33 ceramic plate 35 notch 40 air heat insulating layer

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05B 3/18 H05B 3/18 5F045 3/20 393 3/20 393 3/74 3/74 F term (reference) 3K034 AA10 AA16 AA21 AA34 BA06 BA14 BB06 BB14 BC16 BC23 BC29 CA14 CA22 HA10 JA02 JA10 3K092 PP20 QA04 QA05 QB02 QB32 QB43 QB48 QB76 RF03 RF17 RF27 SS18 SS24 SS26 VV22 VV35 4K029AA04 JA04A04A04 HA03 HA16 HA37 MA29 PA11 PA30 5F045 BB09 BB14 EK09 EK22 EM09

Claims (8)

[Claims] 1. A ceramic heater comprising alumina, mullite, magnesia, aluminum nitride, silicon nitride, etc., and a resistance heating element embedded inside the ceramic heater, wherein one surface of the ceramic heater is provided. A ceramic heater, characterized in that a suction surface capable of sucking a wafer as a workpiece is formed, wherein the ceramic heater body has a high-purity layer in which the composition of the main component exceeds 95%; A ceramic heater comprising a multilayer structure having a relatively low purity layer having a composition of 95% or less. 2. The ceramic heater according to claim 1, wherein a layer forming an adsorption surface of the ceramic heater body is formed of the high-purity layer. 3. The ceramic heater according to claim 1, wherein each layer constituting the ceramic heater body is made of alumina. 4. A ceramic heater according to claim 1, wherein a film-like electrostatic attraction pattern capable of applying a voltage is formed inside said ceramic heater body near said attraction surface. . 5. The film-shaped electrostatic attraction pattern comprises two electrodes, a positive electrode and a negative electrode, and is formed such that the areas of the film-shaped electrostatic attraction pattern of the positive electrode and the film-shaped electrostatic attraction pattern of the negative electrode are different. The ceramic heater according to claim 4, wherein: 6. The ceramic heater according to claim 1, wherein the resistance heating element or the film-like electrostatic attraction pattern is formed in the layer having a relatively low purity. 7. The ceramic heater according to claim 1, wherein the ceramic heater body has a plate shape, and has a thickness of 5 mm or more and 30 mm or less. 8. A step of forming a high-purity ceramic plate by extrusion or pressing using a high-purity ceramic powder having a main component composition of 92% or more; and forming a binder with a main component composition of 95% or less. A step of forming a ceramic green sheet using a ceramic powder having relatively low purity, a step of forming a resistive heating element or a film-like electrostatic attraction pattern on the green sheet by a screen printing method, and the high-purity ceramic plate. Laminating the green sheet on which a resistance heating element or a film-like electrostatic attraction pattern is formed and bonding them with a ceramic paste; and integrally firing the laminated and bonded ceramic plate and the green sheet. And a method for manufacturing a ceramic heater.