JPH10326824A - Manufacture of electrostatic chuck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a scattering of the component of copper from a dielectric layer on the upper surface of a copper electrode formed on the surface of the ceramic board of an electrostatic chuck, and to lower the production cost of the chuck to low cost by method, wherein after the electrode has been formed on the surface of the board by an electroless plating method, an organic resin layer dispersed conductive particles is formed on the upper surface of the electrode by a printing method or the like. SOLUTION: As a method of forming an electrode on the surface of a ceramic board, the surface of the board is rinsed to remove dust. Moreover, after the surface of the board has been cleaned with an alkaline aqueous solution, the surface is activated via processes using etching, conditioning, pre-dipping, putting to catalysis and accelerating. The electrode consisting of an copper layer is formed on the surface subjected to activate treatment by an electroless plating method. Then, an organic resin layer on which conductive particles are dispersed by a printing method or the like is formed on the upper surface of the board as a dielectric layer. That is, in the printing method, the particles are mixed in the resin layer and the dispersed organic resin has only to be applied on the surface by printing and in a spin coater method, the resin layer is dissolved with an alcohol, and the dissolved resin layer has only to be dripped on the surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing an electrostatic chuck, and more particularly to a method for manufacturing an electrostatic chuck using ceramic as a substrate.

[0002]

2. Description of the Related Art Conventionally, there is an electrostatic chuck using a ceramic as a substrate. The electrostatic chuck includes, for example, an electrostatic chuck in which a dielectric layer made of a mixture of alumina and titania covering an electrode and an upper surface thereof is formed on a ceramic substrate surface by a plasma spraying method, or the electrode and the dielectric material are formed on a ceramic substrate surface. There is an electrostatic chuck in which a layer is formed by baking.

[0003] Both of these electrostatic chucks ionize titania contained in the dielectric layer on the upper surface of the electrode,
This is an electrostatic chuck utilizing the fact that the formation of oxygen-deficient TiO _x lowers the insulation resistance of the dielectric layer. When a silicon wafer is placed on the upper surface of the electrostatic chuck and energized in the plasma, the force to attract the silicon wafer by the Johnsen-Rahbek effect acts to fix the wafer. In order to reduce the leakage current (leakage current) flowing between the electrode and the silicon wafer having the opposite pole through the plasma to 1 μA or less, titania is mixed in to reduce the resistance value of the dielectric layer to about 10 ¹⁰ Ω. It was made.

[0004]

However, in an electrostatic chuck in which an electrode and a dielectric layer are formed by a plasma spraying method, the copper at the tip of the nozzle is scraped off during the spraying, and the scraped copper is formed inside the dielectric layer. As a result, there is a problem that in a process of using plasma during semiconductor fabrication, a copper component is scattered from the electrostatic chuck by the plasma and the semiconductor is contaminated with copper. Further, in the case of an electrostatic chuck in which electrodes and a dielectric layer are formed by baking, the baking needs to be performed at a high temperature, so that there is a disadvantage that the process is complicated and the cost is increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to provide an electrostatic chuck which does not cause copper contamination in a semiconductor and reduces the manufacturing cost. It is to provide a manufacturing method.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, after forming a copper electrode on the surface of a ceramic substrate by electroless plating, a printing method or a spinning method is applied to the upper surface thereof. The present invention is based on the finding that the formation of an organic resin in which conductive particles are dispersed by a coater method does not cause the copper component to scatter from the dielectric layer and that an electrostatic chuck with low manufacturing cost can be obtained. Was completed.

That is, the present invention provides (1) a method for manufacturing an electrostatic chuck in which an electrode is formed on the surface of a ceramic substrate and a dielectric layer is formed on the upper surface of the electrode; A method of forming copper by an electroless plating method, the method of forming the dielectric layer is a method of forming an organic resin in which conductive particles are dispersed by a printing method or a spin coater method, and A method of manufacturing an electrostatic chuck, wherein a leak current of the dielectric layer is adjusted to 1 to 0.05 μA by adjusting a mixing ratio of conductive particles to the electrostatic chuck.
(2) The gist of the invention is a method of manufacturing an electrostatic chuck according to claim 1, wherein the ceramic substrate is made of alumina ceramics. This will be described in more detail below.

As a method of forming electrodes on the surface of a ceramic substrate, a ceramic substrate whose surface has been activated is first used. The reason why the activation treatment is performed on the substrate surface is to modify the substrate surface so that copper serving as an electrode is firmly adhered. As this activation treatment, the substrate surface is washed with water to remove dust, and further washed with an alkaline aqueous solution to be cleaned, and then subjected to etching, conditioning, pre-dip, catalyst, and accelerator processing steps. Activate.

An electrode made of copper is formed on the activated surface by electroless plating. The advantage of forming an electrode by this electroless plating method is that a denser electrode can be formed than plasma spraying, and that it can be formed easily without being restricted by equipment, and because the substrate is a thin plate, warpage caused by baking is reduced. There is no such thing. As a specific method of forming this electrode, for example, after copper is formed on the entire surface of the substrate by an electroless plating method, a resist is applied to necessary portions, and unnecessary portions are etched with ferric chloride, and the remaining resist is etched. After removing the solvent with a solvent, or applying a resist in advance to the part of the substrate surface where the electrodes are not formed,
There is a method in which copper is formed on the entire surface of the substrate by an electroless plating method, and a resist portion is lifted off. This allows
A strong copper electrode is formed on the substrate surface. This copper has no magnetism, so in the case of an electrostatic chuck,
It is a preferred electrode.

Next, an organic resin in which conductive particles are dispersed is formed as a dielectric layer on the upper surface on which the electrode is formed by a printing method or a spin coater method. For example, in a printing method, a siloxane (Si-O-Si
Of a conductive compound such as a chain compound), an organic resin in which the particles are dispersed may be applied by printing, and in the spin coater method, it may be dissolved and diluted with alcohol or the like and then dropped. . Whether it is formed by the printing method or the spin coater method may be determined according to the properties of the organic resin to be used. Since no plasma treatment is performed on this dielectric layer, there is no mixing of copper as an electrode.

The leakage current of the formed dielectric layer was 1 to 0.05 μA. If the leak current is larger than 1 μA, it is not preferable because the fine wiring formed on the surface of the silicon wafer is damaged in the IC manufacturing process. This is not preferable because the time required for detaching the silicon wafer becomes longer and the productivity decreases. The leak current can be adjusted by changing the mixing ratio of the conductive particles to change the insulation resistance value of the dielectric layer. If the resistance value is low, the leak current increases, and if the resistance value is high, the leak current decreases.

The ceramics used as the substrate was alumina ceramics. Alumina is preferable because it has excellent properties as ceramics and is inexpensive.Moreover, when forming an electrode on its surface, it is easy to exert an anchor effect in the etching step of the activation treatment, and the adhesive strength of the electrode to the ceramic is improved. Can be strong.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The method of manufacturing an electrostatic chuck will be described in more detail below. First, a sintered body of ceramics having a required size and thickness is prepared by a conventional method using alumina powder. . The surface of the sintered body is ground and polished and flattened to obtain a substrate. The surface of the substrate is washed with water and washed with an aqueous alkaline solution. Next, activation, etching, conditioning, pre-dip, catalyst, and accelerator processing are performed.

On the substrate surface, for example, copper is first formed on the entire surface by an electroless plating method, a resist is applied to a portion which is an electrode, and a portion which is not an electrode is etched with ferric chloride. An electrode is formed by removing with a solvent. A dielectric layer of an organic resin mixed with conductive particles is formed on the upper surface of the electrode by a printing method or a spin coater method.

If an electrostatic chuck is manufactured by the above method,
It is possible to obtain an electrostatic chuck in which the copper component is not scattered from the dielectric layer and the manufacturing cost is low.

[0016]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples of the present invention and Comparative Examples.

(Examples 1 to 3) (1) Formation of electrodes on substrate surface The surface of a sintered body of φ196 × t8 mm manufactured by Nippon Ceratech Co., Ltd. using alumina powder having a purity of 99.5% was prepared. A ceramic substrate was obtained by grinding and polishing. A through hole for a via hole was formed at a necessary portion of the substrate. The substrate surface was washed with water to remove dust, and washed with an alkaline aqueous solution to remove surface dirt. Next, etching, conditioning, pre-dip, catalyst, and accelerator treatments were performed to activate the entire surface of the substrate. A copper layer was formed to a thickness of 5 μm on both surfaces of the activated substrate in a Rochelle salt bath by electroless plating. A resist (AZ1350) is applied to the entire surface of one side, the same resist is applied to the position of the via hole on the other side with a size of φ10 mm, dried and solidified, etched with ferric chloride, and the remaining resist is etched. After removing with toluene, a built-in electrode of φ190 mm was formed on one side, and a conduction electrode of φ5 mm was formed on the other side.

(2) Formation of Dielectric Layer Transparent polyester-based conductive paint containing siloxane as conductive particles (trade name: SP-, manufactured by Taiyo Bussan Co., Ltd.)
2002) was used as an organic resin, and after drying, a dielectric layer was formed on the upper surface of the electrode by screen printing so as to have a thickness of 30 μm. At this time, the amount of siloxane mixed was changed to change the insulation resistance value of the dielectric layer.

(3) Evaluation An 8-inch silicon wafer was placed on the surface of the electrostatic chuck on which the electrodes and the dielectric layer were formed, and the insulation resistance of the dielectric layer was measured with an insulation resistance meter. A DC voltage of 500 V was applied between the wafers, and the leak current was measured with a microammeter. Further, in order to check whether or not the silicon wafer is being sucked, the presence or absence of the suction force was determined by turning over the silicon wafer and determining whether or not the silicon wafer was dropped. Further, the voltage application state is cut off, and the decay time until the attraction force becomes 1 / e (e: natural number 2.7...) At the time of applying the voltage is measured. Pass / fail was judged. Table 1 shows the results.

(Comparative Examples 1-2) For comparison, Comparative Example 1 was the same as Example except that the leak current was larger than 1 μA, and Comparative Example 2 was smaller than 0.05 μA. Table 1 also shows the results.

[0021]

[Table 1]

As apparent from Table 1, in Examples 1 to 3, there was no problem in the separation time. On the other hand, in Comparative Example 1, since the leakage current was larger than 1 μA,
I was worried about the dielectric breakdown of the wiring. In Comparative Example 2,
Since the leak current was smaller than 0.05 μA, the separation time was too long to be practical.

[0023]

According to the manufacturing method of the electrostatic chuck according to the present invention described above, since the plasma treatment is not performed for forming the dielectric layer, there is no mixing of copper into the electrodes.
Since neither the electrode nor the dielectric layer is formed by baking, it is possible to provide a manufacturing method capable of manufacturing an electrostatic chuck with a low manufacturing cost.

Claims (2)

[Claims] An electrode is formed on a surface of a ceramic substrate,
In a method for manufacturing an electrostatic chuck in which a dielectric layer is formed on the upper surface thereof, the method for forming the electrodes is a method for forming copper on the surface of the activated ceramic substrate by electroless plating, and The forming method is a method in which an organic resin in which conductive particles are dispersed is formed by a printing method or a spin coater method, and by adjusting the mixing ratio of the conductive particles into the organic resin, the dielectric layer is formed. 1 leakage current
A method for manufacturing an electrostatic chuck, wherein the pressure is set to 0.05 μA. 2. The method according to claim 1, wherein the ceramic substrate is made of alumina ceramic.