JP2960566B2 - Electrostatic chuck substrate and electrostatic chuck - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic chuck, and more particularly, to an electrostatic chuck, in which a conductive, semiconductive or insulating object is electrostatically attracted and held, and can be easily detached. The present invention relates to an electrostatic chuck useful for a manufacturing process and the like.

[0002]

2. Description of the Related Art In recent years, the processes of manufacturing semiconductors and liquid crystals, and processes such as dry etching, ion implantation, and vapor deposition of semiconductor devices have been automated and made dry. ing.

In addition, as the diameter of a silicon wafer, glass, or the like as a substrate increases, the positional accuracy at the time of patterning has become more and more important with higher integration and miniaturization of circuits. For this reason, vacuum chucks are used for transporting and fixing substrates by suction.However, this type cannot be used because there is no pressure difference under vacuum conditions. In addition, since the attracted portion is locally attracted, there is a disadvantage that the substrate is partially distorted, and high-precision alignment cannot be performed, and thus is unsuitable for recent semiconductor and liquid crystal manufacturing processes. ing.

As an improvement over the above drawbacks, an electrostatic chuck that transports a substrate by using electrostatic force or attracts and fixes the substrate has attracted attention and has begun to be used. But,
When this electrostatic chuck sucks a silicon wafer or glass of a substrate, even if the applied voltage is cut off after the suction, the chucking force continues to work due to the residual charge between the substrate and the electrostatic chuck,
There is a disadvantage that a state where the substrate cannot be removed often occurs. This phenomenon occurs because the electric charge induced in the substrate by the electric field applied to the chuck electrode when the substrate is adsorbed is accumulated in the insulating layer such as silicon oxide on the surface of the silicon wafer or in the glass as the insulator. This is because even if the applied voltage is cut off for the purpose, the electric charge remains in the insulating layer and cannot be moved, and a residual electrostatic force is generated.

[0005]

Therefore, in order to reduce the residual electrostatic force of this electrostatic chuck, the material of the insulating dielectric layer is not oxidized and a low-resistance transition such as titanium oxide or lead titanate is used. A method of adding a metal has also been proposed (see JP-A-62-94953), but in this case, the withstand voltage is significantly reduced,
When a voltage is applied to obtain an electrostatic force, there is a disadvantage that a device function is damaged by discharge due to dielectric breakdown or a leak current flowing on the chuck surface.

[0006]

SUMMARY OF THE INVENTION The present invention relates to an electrostatic chuck substrate and an electrostatic chuck which solve such disadvantages, and has an insulating dielectric made of a sintered body and / or a sprayed ceramic above and below an electrode. covered with the body layer, insulating
A take-out portion of the edge of the dielectric layer an electrostatic chuck substrate and the electrostatic chuck plate of the electrode on the surface which does not adsorb the substrate characterized by comprising comprises a <br/> conductive thin film made of a metal
The gist of the invention is to provide an electrostatic chuck formed by attaching a lead wire so as to supply power from the outside and bonding a ceramic base material.

That is, the present inventors have conducted various studies to develop an electrostatic chuck substrate and an electrostatic chuck which do not have the disadvantages described above, and as a result, as a method of removing residual charges, a substrate having an insulating dielectric layer has been developed. Metal on the surface that does not absorb
Assuming that provided Ranaru thin conductive film, easily move residual charge in the insulating dielectric layer is the presence of this conductive film, because it is neutralized, can be easily detached objects if off the applied voltage at the time of desorption Thus, the present invention has been completed. This will be described in detail below.

[0008]

The present invention relates to an electrostatic chuck substrate and an electrostatic chuck, in which the upper and lower electrodes are covered with an insulating dielectric layer, and a conductive thin film is provided on one surface of the insulating dielectric layer. The gist of the present invention is an electrostatic chuck substrate and an electrostatic chuck formed by bonding ceramics to the electrostatic chuck substrate.

The electrodes constituting the electrostatic chuck substrate of the present invention may be made of a conductive metal such as copper, aluminum, titanium, molybdenum, and tungsten. photo litho graph <br/> may perform I over or plating or the like. The type of this electrode may be a monopolar type using one of the electrodes as a substrate, but it may be a bipolar type in which two electrodes are opposed to each other.

The insulating dielectric layer constituting the electrostatic chuck substrate is made of a ceramic sintered body made of alumina, aluminum nitride, zirconia, quartz, boron nitride, sialon or a mixture thereof, or a plasma of these ceramics. The ceramics may be formed by thermal spraying, but the ceramics may be added with a high dielectric substance as long as the resistance is not reduced. The electrostatic force of this electrostatic chuck is proportional to the square of the applied voltage and inversely proportional to the square of the thickness of the insulating dielectric layer that absorbs the substrate. The thinner the better, the better. However, the thickness may be in the range of 100 to 4,000 μm in view of ease of processing and a range in which no discharge occurs between the substrate and the electrode.

The electrostatic chuck substrate of the present invention is formed by covering the above-mentioned electrodes with the above-mentioned insulating dielectric layer on the upper and lower sides. Is required.

[0012] The conductive thin film such as carbon, nitrogen, titanium,
It may be made of conductive ceramics such as zirconium boride, and metals such as aluminum, titanium, copper, iron, nickel, molybdenum, and tungsten. Is preferably selected from aluminum, titanium, and copper.
This thin film is formed by applying a solution obtained by adding these metal powders to a silicone resin or an epoxy resin to an insulating dielectric film and bonding them, or by directly applying the metal powder or the metal foil to the insulating dielectric layer. And heat it, or print this metal powder paste by screen printing,
What is necessary is just to fuse.

The thus produced electrostatic chuck substrate of the present invention has the advantage that the residual electrostatic force caused by the residual charge can be quickly neutralized and removed by the conductive thin film. Has the disadvantage that it is usually thin and fragile to handle, so the electrostatic chuck using this is made of alumina, zirconia,
It is preferable that the substrate be bonded to a ceramic substrate such as quartz, aluminum nitride, boron nitride, or sialon.

[0014]

Next, examples of the present invention will be described. Example 1 To 100 parts by weight of a mixture of 95% by weight of aluminum nitride powder and 5% by weight of yttria, 8 parts by weight of butyral resin, 50 parts by weight of trichloroethylene, 10 parts by weight of ethanol and 2 parts by weight of dioctyl phthalate were added, and then the mixture was placed in a ball mill. At 35.degree. C. to form a slurry, which is treated with a vacuum defoamer to disperse a part of the solvent to a viscosity of 38,000 centipoise, and the slurry is thickened using a doctor blade. Make a 1mm green sheet, and from this green sheet, 150m in diameter
Two disks of mφ were cut out.

Further, bipolar electrodes are concentrically printed on the one disk at an interval of 1 mm by screen printing using a tungsten paste, and another green sheet disk is laminated on the printed surface and laminated by press. The laminated body is fired at 1,880 ° C. in an atmosphere of 20% hydrogen gas and 80% nitrogen gas to produce a laminated sintered body. Then, aluminum is applied to one surface of the laminated plate by plasma spraying. A conductor thin film was provided by welding over the entire surface at a thickness of 150 μm to form an electrostatic chuck substrate.

Then, an aluminum nitride sintered body having a thickness of 10 mm is placed on the thus-obtained electrostatic chuck substrate, heated to 700 ° C. in a vacuum, and melt-bonded. The extraction portion was plated with nickel and gold, and two lead wires were attached with solder to form an electrostatic chuck.

Next, a current of 1 kV DC was applied between the lead wires of the electrostatic chuck thus produced to attract a silicon substrate having a diameter of 6 inches, and then the applied voltage was cut off. Since there was no charge, the silicon substrate could be immediately detached, but for comparison, an electrostatic chuck was made in the same manner as above without the conductive thin film on the electrostatic chuck substrate, and a similar test was performed on this. As a result, the silicon substrate could not be detached for 12 seconds even after the applied voltage was cut off due to residual electrostatic force.

Example 2 Nickel plating is applied to an alumina sintered body having a thickness of 0.8 mm and a diameter of 200 mm to form the same electrode as in Example 1, and an alumina powder having a thickness of 0.1 mm is formed thereon by plasma spraying. 5
mm, and a metal mixed paste of titanium / copper = 25/75 (weight ratio) is printed on the entire surface with a thickness of 145 μm by a screen printing method to form an electrostatic chuck substrate. Was heated at 1,100 ° C. under vacuum to bond the alumina sintered body having a diameter of 15 mm and a diameter of 200 mmφ to form an electrostatic chuck.

Next, a voltage of 1 KV DC was applied to the thus-obtained electrostatic chuck in the same manner as in the first embodiment.
After the silicon substrate having a diameter of 8 inches was electrostatically adsorbed, the state of desorption when the applied voltage was turned off was examined. As a result, the desorption was immediately possible.

[0020]

According to the present invention , the power supply of the electrostatic chuck is
When pressure is removed, residual charge is quickly neutralized and removed.
Therefore, the adsorbed object can be desorbed
In addition to the effect, the dry process of the semiconductor industry
Thermal conductivity during cooling and heating of workpieces
To provide a uniform heat distribution to the adsorption target, thus increasing the area.
Has the effect of facilitating uniform processing of substrates
You .

[0021]

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Shinji Kojima 2-13-1 Isobe, Annaka-shi, Gunma Prefecture Shin-Etsu Chemical Co., Ltd. Precision Functional Materials Laboratory (56) References JP-A-63-194345 (JP) , A) JP-A-2-76658 (JP, A) JP-A-62-283037 (JP, A) JP-A-1-11542 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB Name) B23Q 3/00-3/154 B23Q 3/16-3/18

Claims (3)

(57) [Claims] An upper and lower electrode is covered with an insulating dielectric layer made of a sintered body and / or sprayed ceramic,
An electrostatic chuck substrate comprising a conductive thin film made of metal on a surface of a conductive dielectric layer on which a substrate is not adsorbed . 2. A conductive thin film made of a metal is aluminum,
2. The electrostatic chuck substrate according to claim 1, wherein the substrate is selected from titanium or copper. 3. The electrostatic chuck according to claim 1, wherein
Apply power from the outside so that the electrode
An electrostatic chuck characterized by attaching a lead wire and bonding a ceramic substrate.