JP2003060020A - Electrostatic chuck apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic chuck apparatus in which a contact thermal resistance between the back of a substrate and an electrostatic chuck is reduced, in which the temperature on the surface of the substrate can be controlled with high accuracy and whose plasma resistance and durability and high. SOLUTION: As an insulating layer on the electrostatic chuck 10, an insulating viscous fluid or a low-hardness gel-like substance is used at least for a first electrical insulating layer 13. Since the holding face of the layer 13 composed of the viscous fluid or the gel-like substance is deformed by following the shape of the back of the substrate 14, it adheres uniformly nearly on the whole face. The exposed face of the layer 13 may be covered with a second corrosion-resistant electrical insulating layer, and a third electrical insulating layer composed of a highly insulating layer may be arranged between the layer 13 and a metal insulating-layer support plate 11. An electrode 12 can be embedded at the inside of the layer 13, and it can be fixed and bonded to the rear surface of the second insulating layer or to the surface of the third insulating layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic chuck capable of controlling the temperature of a substrate surface, having excellent heat transfer performance and durability, and having high adhesion to a workpiece.

[0002]

2. Description of the Related Art Conventionally, an electrostatic chuck is used to hold a semiconductor substrate in various film forming steps, dry etching steps, and ion implantation steps in a semiconductor manufacturing process. In this electrostatic chuck, electrodes are embedded in an electrically insulating layer, the upper surface of the insulating layer is used as a holding surface of a substrate, and a DC voltage is applied between the holding surface and the substrate, whereby coulomb due to dielectric polarization is applied. The attraction force called Johnson-Rahbek force is generated by the force and minute leakage current, and the substrate is attracted and held on the holding surface.

The electrically insulating layer of these electrostatic chucks is disclosed in, for example, JP-A-7-106300 and JP-A-9-.
As described in JP-A-298233, JP-A-2000-113850, JP-A-2000-286332, etc., it is proposed to use a ceramic material such as alumina or a polymer material such as polyimide or silicone rubber, Some have been put to practical use.

According to the above-mentioned JP-A-7-106300, in order to improve the plasma resistance of the electric insulating layer, the exposed surface of the electric insulating layer made of a polymer organic film is coated with a fluororesin. There is. Further, Japanese Patent Laid-Open No. 2000-11385
According to Japanese Unexamined Patent Publication No. 0, various kinds of ceramics and glass are used for the electric insulating layer, and the exposed surface thereof has resistance to plasma and the like, and is excellent in heat resistance, chemical resistance, and aging resistance.
A silicone resin such as TE, methylphenyl vinyl, or fluorosilicone is coated as an erosion-preventing insulating film.
In Japanese Patent Laid-Open No. 2000-286332, a polyimide resin film is used for the electric insulation layer, and the surface thereof is covered with a protective film made of a fluororesin to prevent the corrosion of the polyimide resin film due to etching.

Further, in the above-mentioned Japanese Patent Application Laid-Open No. 9-298233, an electrode is arranged on a first insulating layer made of a heat conductive silicone rubber on a metal supporting plate, and the hardness is 85 or less on this electrode. , A second insulating layer made of a heat conductive silicone rubber having a surface roughness of 5 μm or less is formed to secure heat dissipation, improve the adhesion to the substrate, suppress the contact thermal resistance to a low level, and reduce the temperature of the substrate. An electrostatic chuck that accurately and uniformly and uniformly is disclosed.

[0006]

By the way, since the ceramic used as the electric insulating layer has excellent thermal conductivity and plasma resistance, the electrostatic chuck made of ceramics is widely used in etching equipment, CVD equipment and the like. However, since the material is too hard to fit in the substrate (semiconductor wafer), the substrate and the electrostatic chuck are practically not in contact with each other during the electrostatic chuck, and the heat transfer performance is very poor. Was becoming.

On the other hand, since an electrostatic chuck made of polyimide can be manufactured at low cost, it is often used in an etching apparatus, but since it is hard and has poor thermal conductivity, it has poor heat transfer performance like ceramics. Further, the plasma resistance is not sufficient, so that there is a problem in durability.

Therefore, when these electrostatic chucks are used under reduced pressure, in order to promote heat transfer between the substrate and the susceptor which is a support plate of the electrostatic chuck, helium is provided between the substrate and the electrostatic chuck. In many cases, an inert gas such as gas is supplied to improve heat transfer performance. However, supplying the inert gas complicates the entire apparatus, and there is concern that the leak of the inert gas may affect the process.

On the other hand, an electrostatic chuck using silicone rubber or the like as disclosed in Japanese Patent Laid-Open No. 9-298233 mentioned above,
Compared to an electrostatic chuck that uses ceramics or polyimide, it can reduce contact thermal resistance, so it has excellent heat transfer performance, but it is poor in plasma resistance and durability, and is actually used in etching equipment. Since it is difficult to do so, it was limited to some applications such as an ion implantation device.

Further, Japanese Patent Laid-Open No. 2000-113850 proposes coating the upper surface of an electrostatic chuck made of silicone rubber with diamond-like carbon (DLC), fluororesin, polyimide or the like. However, these coatings focus only on the releasability from the wafer, and the peripheral side surface of the electrical insulating layer made of silicone rubber is still exposed to the outside, and the plasma resistance is not taken into consideration from these materials. It has not been done.

Further, when a silicone rubber electrostatic chuck is coated with a material having high hardness such as diamond-like carbon (DLC), fluororesin, or polyimide to improve plasma resistance, it is usually When the hardness is about the same as the silicone rubber, the contact heat resistance increases, and the heat transfer performance cannot be improved as expected. As a result, it becomes impossible to coat with a sufficient thickness to withstand plasma,
In reality, it cannot be used for etching equipment.

The present invention has been made to solve the above problems, and a first object of the present invention is to use a material that is easily compatible with the substrate for the electric insulating layer to reduce the contact thermal resistance between the substrate and the substrate. It is to provide an electrostatic chuck having improved heat transfer performance, and a second object thereof is to provide an electrostatic chuck excellent in corrosion resistance. Other objects will be made clear by the following description.

[0013]

The first object is achieved by having the constitution of the invention according to claim 1. That is, the invention according to claim 1 is an electrostatic chuck device in which an electrode is arranged inside an electrically insulating layer fixed on a metal support plate, and the upper surface of the insulating layer is attracted and held by static electricity as a substrate holding surface. The electrostatic chuck device is characterized in that at least a part of the electric insulating layer covering the electrode is made of a viscous fluid or a gel material having a low hardness.

By adopting a viscous fluid or a gel material having a low hardness as a part of the electric insulating layer, it is possible to utilize the physical properties of the viscous fluid or a gel material having a low hardness in accordance with the shape of the other side, and The substrate holding surface of the electric chuck can be brought into close contact with the back surface of the substrate evenly, and the vacuum layer can be substantially eliminated at the contact interface even in a vacuum environment during etching processing, for example. It reduces the contact thermal resistance and ensures high thermal conductivity.

Here, examples of the viscous fluid include various greases having a thermal conductivity of 1 or more, silicone oil, and the like, and the gel substance is preferably a polymer material. Examples thereof include silicone gel, polyurethane gel, epoxy gel and the like. Gelation of gel-like polymer materials occurs when condensation reactions of monomers containing polyfunctional groups, polymer solutes form intermolecular reactions such as cross-linking agents or ionic bonds, and hydrogen bonds or hydrophobic bonds between solutes form cross-linking points. Occurs in

Among the above gel-like polymer materials, silicone gel is most preferable because it has the following excellent characteristics. The basic structure of silicone gel is a material that has a property intermediate between silicone rubber and silicone oil by cross-linking dimethyl siloxane polymers by chemical bonds, and is a material that is much softer and more shape-retaining than rubber. .

The crosslink density is 1 of that of ordinary silicone rubber.
It is controlled to / 3 to 1/10. In addition, there is no hydrogen bond between water molecule and polar group like general hydrogel,
Since the polymer skeleton is thermally stable, the gel state can be maintained in a wide temperature range. Furthermore, this silicone gel has low temperature dependence of physical properties, heat resistance, relatively high mechanical strength, adjustable viscoelasticity, easy molding, and electrical and weather resistance. It has features such as excellent.

The low-hardness gel polymer material used in the present invention needs to have low hardness and low elastic modulus so that the contact thermal resistance can be reduced, and the JIS K6301 hardness is 10
Hereinafter, the penetration of JIS K2207 is 5 or more, and particularly preferably 50 to 200.

If the gel-like polymer material is too thin, the mechanical strength and the dielectric breakdown voltage will decrease.
Further, it is not necessarily effective in reducing the contact thermal resistance. on the other hand,
If the wall thickness is too thick, the heat resistance will increase accordingly. Experiments have shown that the gel-like polymer material has an optimum value at a certain wall thickness. Its thickness is 0.1-2 mm
Is preferred. In particular, when used as an electrostatic chuck, its attractive force is inversely proportional to the square of the thickness of the dielectric layer, so that it is preferably 1 mm or less.

The invention according to claim 2 defines a case where all of the electric insulating layer is made of a gel material having a low hardness. As described above, the electrostatic chuck provided with the electric insulating layer of the gel-like substance alone has a shape-retaining property and is extremely flexible. The holding surface of the insulating layer is deformed according to the irregularities on the back surface of the substrate and adheres almost over the entire surface, so that the contact thermal resistance between the substrate and the adsorption surface can be suppressed low. as a result,
In particular, since the cooling efficiency can be improved, it becomes possible to control the temperature of the substrate with high efficiency and high accuracy, and it is possible to cope with the lowering of the substrate temperature and the energy saving of the cooling device.

Further, the electrostatic chuck of the present invention is, as described above,
Since the contact heat resistance can be suppressed to be extremely low, the heat transfer performance is excellent even in a vacuum, and the conventionally used cooling gas for promoting heat transfer or the like becomes unnecessary. Further, the gel-like substance can be imparted with high heat conductivity by adding a heat conductive filler. As the heat conductive filler added to the gel substance, alumina, aluminum nitride, boron nitride,
There is silicon nitride and the like.

The thermal conductivity thereof is preferably 1 W / mK or more. As a silicone gel sheet molded article, λ gel (thermal conductivity 6.5 W /
m ・ K) etc. On the other hand, as the electrode material,
Examples thereof include metal-based conductors such as copper, aluminum, nickel, silver and tungsten, and ceramics such as titanium nitride.

According to a third aspect of the present invention, in the electrostatic chuck according to the first aspect, the electrically insulating layer is composed of at least two layers, and at least one of the inner layers is the viscous fluid or a gel of low hardness. The electrostatic chuck device is composed of a material layer, and the outer surface thereof is covered with at least a second insulating layer having corrosion resistance.

The second insulating layer usable in the present invention includes:
For example, a polyimide resin or a fluororesin can be used. As the polyimide resin, not only condensation reaction type non-thermoplastic wholly aromatic polyimide (PI) but also thermoplastic polyimide, addition reaction type thermosetting polyimide polyether imide (PEI), polyamide imide ( PAI) etc. are also included. Examples of the fluororesin include PTFE, PFA, ETFE and FEP, and particularly chemically stable PTFE and PFA are preferable.

In addition, an electrical insulating layer made of a gel-like substance,
After coating with PFA, the surface is further coated with PTFE, or an electrically insulating layer made of a gel-like substance is coated with PTFE.
It is also possible to employ a multi-layer structure in which the outermost layer is covered with a corrosion-resistant insulating layer, such as a three-layer structure in which the surface is covered with a polyimide resin.

The thickness of the second insulating layer is preferably thin from the viewpoint of contact thermal resistance, but if it is too thin, it cannot fully serve as a protective film and the mechanical strength is lowered. In particular, when a low hardness gel polymer material is used for the first insulating layer as in the electrostatic chuck of the present invention, if the thickness of the protective film is 10 μm or less, the strength cannot be practically used and at the same time the corrosion resistance is low. The sex is not enough. The film thickness is 50 μm
If the temperature exceeds the range, the hardness of the protective film increases, the electrical insulating layer made of a gel-like substance does not undergo the expected deformation, and the contact thermal resistance between the second insulating layer and the substrate increases, resulting in the expected transmission. Thermal performance cannot be obtained.

As described above, by optimizing the hardness and elasticity of the electrical insulating layer made of a gel material and the thickness of the corrosion-resistant second insulating layer coated on the insulating layer, high heat transfer performance can be obtained. At the same time, the durability can be improved without impairing the cooling characteristics of the substrate.

According to a fourth aspect of the present invention, in the electrostatic chuck of the first aspect, the electric insulating layer is composed of at least three layers, and at least one of the inner layers is a viscous fluid layer or a gel material having a low hardness. 4. The electrostatic chuck device according to claim 3, wherein the electrostatic chuck device is formed of layers, and a third electrically insulating layer having a high insulating property is further disposed on at least an upper surface of the metal supporting plate of the electrically insulating layers.

Generally, the viscous fluid layer can enhance its insulating property, but since it has fluidity, it must be enclosed in the sealing layer. On the other hand, gel material,
In particular, in the case of a gel-like polymer material, it is possible to obtain a required thermal conductivity, and it is possible to use the gel-like polymer material alone as an electric insulating layer of an electrostatic chuck as described in claim 2 above. It is inferior in electric insulation property compared with the insulating material.

Therefore, according to the present invention, a third electrically insulating layer having a high insulating property is provided directly on the upper surface of the metal supporting plate of the electrostatic chuck, and the insulating layer and the corrosion-resistant first electrically insulating layer are provided on the surface. The two insulating layers enclose the viscous fluid layer or the gel-like substance layer. As a result, the shape-retaining property of the viscous fluid layer can be ensured, or the portion of the gel-like substance having poor insulation properties can be supplemented by the insulating layer directly arranged on the support plate. As the high insulation layer arranged on this support plate,
Similar to the above-mentioned corrosion-resistant insulating layer, for example, various polyimide-based resins and fluorine-based resins are used.

The electrode is arranged directly on the lower surface of the corrosion-resistant second insulating layer as in the invention according to claim 5, or as in claim 6, the third insulating material having high insulation property on the support plate. It is preferably placed directly on top of the layer. Arranging the electrodes at such portions facilitates the molding of the various insulating layers. This electrode can be fixed to the lower surface of the second insulating layer or the upper surface of the third insulating layer having a high insulating property on the support plate with an adhesive, for example, but it should be formed directly by vapor deposition or the like. You can also

Furthermore, when the electrodes are directly arranged on the lower surface of the second insulating layer, the electrodes approach the substrate placed on the upper surface of the chuck, and the electrostatic attraction force increases. Further, when the electrode is directly arranged on the upper surface of the third insulating layer having a high insulating property on the support plate, the electrode is fixed in a stable state, and the function as the electrode is stably obtained.

The invention according to claim 7 is characterized in that the second insulating layer covers another electrically insulating layer and an externally exposed surface of the metal supporting plate around the insulating layer. With such a configuration, not only the insulating layer directly bonded and fixed on the support plate via an adhesive, but also the plasma resistance and etching resistance are improved with respect to the adhesive as well, heat resistance, chemical resistance, An electrostatic chuck device excellent in aging resistance can be obtained.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be specifically described below with reference to the examples shown in the accompanying drawings. Figure 1
Shows a schematic structure of the electrostatic chuck device according to the first embodiment of the present invention, and FIG. 3 shows a schematic structure of the electrostatic chuck device according to the second embodiment of the present invention.

The electrostatic chuck according to the present invention is mounted and fixed on a metal support plate 11 as shown in FIGS. As shown in FIG. 1, the basic configuration of the electrostatic chuck 10 of the present invention is to employ a low hardness gel-like substance, which is one of the features of the present invention, as an electric insulating layer of the electrostatic chuck. FIG. 1 shows an embodiment in which a gel polymer material is used alone as the electric insulating layer 13. The electrode 12 is an electrically insulating layer 1 made of a gel polymer material.
It is completely covered by No. 3.

The present invention also includes covering the exposed surface portion of the first insulating layer 23 with a second insulating layer 24 made of a corrosion-resistant insulating layer such as fluororesin or polyimide resin, as shown in FIG. . Examples 1 and 2 described below
Then, the electrostatic chucks 10 and 20 according to the present invention are used by being bonded to the cooling susceptor (metal support plate) 11 via, for example, an adhesive.

Further, according to the present invention, as shown in FIGS. 4 and 5, a third insulating layer 25 may be arranged between the metal supporting plate 21 and the first insulating layer 23. As the third insulating layer, various polyimide resins, PEE
A heat-resistant and highly insulating resin such as K (polyether ether ketone), PBI (polybenzimidazole), PPS (polyphenylene sulfide) is used.

In this case, the electrode 21 is the third insulating layer 25.
On the upper surface or the back surface of the corrosion-resistant insulating layer 24 which is the second insulating layer, or is directly formed by bonding with an adhesive. Further, when the first insulating layer 23 is completely covered with the second and third insulating layers, the material of the first insulating layer 23 is, for example, excellent in insulation and thermal conductivity of various greases and oils. A viscous fluid can also be used.

(Embodiment 1) An embodiment of the present invention is shown in FIG. The electrostatic chuck 10 is mounted on a support plate 11 for cooling in a plasma etching process, for example.
The electrostatic chuck 10 is composed of an electrode 12 and an electric insulating layer 13 that covers the electrode 12 and is a low hardness gel polymer material. A DC voltage is applied to the electrode 12 between the substrate holding surface of the electrostatic chuck 10 and the substrate 14 via a lead wire 15, which is called a Coulomb force due to dielectric polarization or a Johnson-Rahbek force due to a minute leakage current. A suction force is generated to suck and hold the substrate 14 on the holding surface. Normally, the lead wire 15 is made of PTFE or FE which has excellent withstand voltage.
Electric wires coated with fluororesin such as P and PFA are used.

In the present invention, the hardness of the electrical insulating layer 13 made of a gel-like polymer material is "low hardness", as described above, JIS K6301 has a hardness of 10 or less, and JIS K2207 needle. Admission is 5 or more, especially 50 ~
It is preferably 200. In this way the electrical insulation layer 1
Since 3 has a low hardness and a low elastic modulus, the holding surface of the electrostatic chuck 10 is deformed to follow the shape of the lower surface of the substrate 14, and the whole surface is in close contact with the electric insulating layer. The contact thermal resistance of 13 can be reduced.

Electrically insulating layer 13 made of gel polymer material
If the wall thickness is too thin, the mechanical strength and dielectric breakdown voltage will decrease, and it will not necessarily be effective in reducing the contact thermal resistance.
On the other hand, if the wall thickness is too thick, the thermal resistance will increase by that amount, and as a result, the thermal resistance of the electric insulating layer 13 itself will increase. That is, the thickness of the electrical insulating layer 13 made of the gel polymer material has an optimum value within a certain range, and the value is preferably 0.1 to 2 mm.
In particular, when used as the electrostatic chuck 10, the attraction force is more preferably 1 mm or less because it is inversely proportional to the square of the thickness of the dielectric layer. Further, the insulating layer 1
The thermal conductivity of 3 is preferably 1 W / m · K or more, and an insulating thermally conductive filler such as alumina, aluminum nitride, boron nitride, or silicon nitride may be added.

Examples of the gel polymer material that is a constituent material of the electric insulating layer 13 include silicone gel, polyurethane gel, and epoxy gel. Among them, silicone gel is most preferable because it has the following excellent characteristics. It is effective. In this embodiment, silicone gel is used as the gel polymer material.

The basic structure of the silicone gel is a material having an intermediate property between silicone rubber and silicone oil by cross-linking a dimethyl siloxane polymer and having a much softer shape retention property than rubber. In particular, its crosslink density is controlled to be as low as 1/3 to 1/10 that of ordinary silicone rubber. Since the polymer skeleton of this silicone gel is thermally stable, the gel state can be maintained in a wide temperature range, and as described above, the physical properties have little temperature dependence and heat resistance and mechanical strength. Electrical characteristics with relatively high viscoelastic property adjustment and easy molding
It has excellent properties such as excellent weather resistance.

Next, in a vacuum chamber capable of reducing the pressure to 1 Pa, a case in which an aluminum plate and a heater are directly mounted on a cooling aluminum plate and a case where various electric insulating layers are mounted on the cooling aluminum plate When the aluminum plate and the heater are sequentially mounted on the aluminum plate, the aluminum plate is heated by the heater on the upper side under the pressure of 100 gf / cm ² respectively, and the aluminum plate temperature becomes equilibrium. Measure the temperature and the temperature difference between the inlet and outlet of the coolant that cools the aluminum plate,
The cooling performance was confirmed by calculating the contact thermal resistance between the aluminum plate and the insulating layer from these measured values.

FIG. 2 shows the results of those experiments. In addition,
The contact heat resistance ratio value shown in the figure is based on the contact heat resistance value of silicone rubber being 1. As can be understood from the figure, when the electrical insulating layer is not inserted, the contact thermal resistance is extremely high under vacuum (1 Pa), but the silicone gel or silicone rubber of the present invention has low hardness and low elastic modulus. It can be understood that the contact thermal resistance under vacuum is greatly improved by inserting. In particular, the silicone gel having the above hardness according to the present invention is most effective. In addition, as an electrical insulation layer, a relatively low hardness PTFE (F5
0) Some improvement can be seen when resin is inserted,
It can be seen that even if a polyimide having a high hardness and a high elastic modulus is inserted, the contact thermal resistance increases, and the contact thermal resistance becomes higher than that when the insulating layer is not inserted.

(Second Embodiment) FIG. 3 shows a schematic structure of an electrostatic chuck device according to a second embodiment of the present invention. The electrostatic chuck 20 is bonded onto a support plate 21 with an adhesive. In the electrostatic chuck 20 of the present embodiment, the electrode 22 is covered with the first insulating layer 23 made of the low hardness silicone gel as in the above embodiment, and the exposed surface portion of the insulating layer 23 is protected against corrosion. It is covered with a second insulating layer 24 made of a film.

As the corrosion-resistant protective film 24 used in this embodiment, for example, a polyimide resin or a fluorine resin can be used, and the polyimide resin is a condensation reaction type non-thermoplastic wholly aromatic polyimide (PI). ), As well as thermoplastic polyimide, and polyetherimide (PE) which is an addition reaction type thermosetting polyimide.
I), polyamide imide (PAI) and the like are also included.

As the fluororesin, PTFE, PFA,
Examples thereof include ETFE and FEP, and particularly chemically stable PTFE and PFA are preferable. Further, in this embodiment, for example, a silicone gel is coated with PFA and then with PTFE, or a silicone gel is coated with PTFE and then with polyimide to form a three-layer structure. May be. That is, in the present invention, as long as the corrosion-resistant protective film is provided on the outermost layer, a multi-layer structure in which various insulating layers are freely combined between the gel polymer material and the outermost layer may be used.

The thickness of the anticorrosion protective film is preferably thin from the viewpoint of contact thermal resistance, but if it is too thin, the function as a protective film cannot be sufficiently achieved and the mechanical strength also decreases. As will be apparent from the experimental results described below, when a low hardness gel polymer material is used for the first insulating layer 23 as in the electrostatic chuck 20 according to the present embodiment, a corrosion-resistant protective film having a thickness of 50 μm is used. Also, since sufficient cooling characteristics can be obtained, the second insulating layer 24 in the electrostatic chuck 20 of the present invention can be obtained.
The thickness of the corrosion-resistant protective film is preferably 10 to 50 μm.

Next, as in the first embodiment, in a vacuum chamber capable of reducing the pressure to 1 Pa, various electrical insulating layers were mounted on an aluminum plate for cooling, and an aluminum plate and a heater were further formed thereon. Installed sequentially, 10 each
With the pressure of 0 gf / cm ² applied, the temperature of the aluminum plate temperature and the temperature difference between the inlet and outlet of the cooling liquid cooling the aluminum plate when the aluminum plate temperature is in an equilibrium state by heating with the upper heater Was measured, and the contact thermal resistance between the aluminum plate and the insulating layer was calculated from these measured values to confirm the cooling performance.

FIG. 4 shows a silicone rubber having a thickness of 300 μm, a silicone gel having a thickness of 300 μm, and a thickness of 12 μm and 25 μm on the silicone gel.
The experimental result when three kinds of fluororesin layers, which are corrosion-resistant protective films of 50 μm, are laminated is shown. Also in the figure, the contact thermal resistance of each sample is a relative contact thermal resistance value when that of silicone rubber is 1.

When the fluororesin is laminated on the silicone gel, the contact thermal resistance is increased as compared with the case of the gel alone, but even when the fluororesin of 50 μm is laminated, the contact thermal resistance is the silicone rubber alone. It can be understood that it is lower than when. That is, when a low hardness gel polymer material having a penetration of about 50 is used as the first insulating layer 23, a sheet having a thickness of about 50 μm is laminated as a corrosion-resistant protective film so as to have sufficient plasma resistance. However, it can be seen that the cooling characteristics are superior to those of the conventional electrostatic chuck made of silicone rubber.

(Embodiment 3) The structure of the electrostatic chuck according to the third embodiment is the same as that of the second embodiment shown in FIG. 3, and the electrostatic chuck 20 has electrodes made of the low hardness silicone gel. Is covered with a first insulating layer 23, and the exposed surface portion of the insulating layer 23 is covered with a second insulating layer 24 made of a corrosion-resistant protective film. However, the difference from the second embodiment is that a polyimide resin is used as the material of the second insulating layer 24, which is a corrosion-resistant protective film, instead of the fluororesin.

FIG. 5 shows a sheet material inserted between the aluminum plates, which is the same as that of the second embodiment and has a thickness of 300 μm.
When a silicone rubber having a thickness of m, and a silicone gel having a thickness of 300 μm are used, the thickness of the silicone gel is 12 μm, 25 μm, 50 μm and 75 μm.
The results of each experiment when a sheet material in which four kinds of polyimide resin layers of μm are laminated are inserted are shown. Also in the figure, the contact thermal resistance of each sample is a relative contact thermal resistance value when that of silicone rubber is 1.

As can be understood from the figure, when compared with the second embodiment, the first insulating layer 2 made of silicone gel is used.
2 is made of polyimide resin as a corrosion-resistant protective film
Even when covered with the insulating layer 24, its contact thermal resistance is the second
It can be understood that the same values as those in the second embodiment are exhibited up to the thickness of the insulating layer 24 of 50 μm. However, when the wall thickness exceeds 50 μm, it is larger than the contact thermal resistance of the electrostatic chuck made of silicone rubber.

As described above, even if a corrosion-resistant protective film made of polyimide having an elastic modulus of several GPa and a relatively high hardness is used,
It was demonstrated that the intended function of the present invention was sufficiently achieved. From these experimental results, it was confirmed that the electrostatic chuck 20 according to the second and third examples is a high-performance electrostatic chuck having both excellent cooling characteristics and plasma resistance (durability).

(Embodiments 4 and 5) FIGS. 6 and 7 show the fourth and fifth embodiments of the present invention. According to the fourth embodiment, the supporting surface of the metal supporting plate 21 has a high insulating property.
The insulating layer 25 is directly adhered with an adhesive, and the electrode 22 is further fixed to the upper surface thereof by the same bonding or vapor deposition. Further, the first insulating layer 23 of a gel polymer material is fixed by molding or molding made of the same material as that of the first embodiment so as to cover the electrode 22. Finally,
All the exposed surfaces of the first insulating layer 23 and the third insulating layer 25 are covered with the second insulating layer 24 made of the same material as in the second embodiment. In this embodiment, since the electrode 22 only needs to be fixed to the upper surface of the third insulating layer 25, not only the electrostatic chuck 20 is easily manufactured, but also the fixing position of the electrode 22 becomes immovable. Compared with the second embodiment, the distance between the electrode 22 and the substrate mounted on the electrostatic chuck 20 can be made uniform, so that the electrostatic chuck 20 can perform stable adsorption.

In the fifth embodiment, as in the fourth embodiment, the third insulating layer 25 having a high insulating property is directly adhered to the supporting surface of the metal supporting plate 21 with an adhesive. A first insulating layer 23 made of the same material as in Example 1 is molded or molded on the upper surface of the gel polymer material. Further, the electrode 22 is fixed to the upper surface of the first insulating layer 23, and
All the external exposed surfaces of the electrode 22, the first insulating layer 23, and the third insulating layer 25 are covered with the second insulating layer 24 as in the fourth embodiment. In this embodiment, the electrode 2
The fixing position of No. 2 becomes immovable, and not only the stable adsorption by the electrostatic chuck 20 can be obtained as in the fourth embodiment, but also in comparison with the fourth embodiment, the electrode 22 and the electrostatic chuck 20 have the same surface. Since the distance to the substrate to be placed is close, the electrostatic attraction force increases.

Further, in these embodiments, the third insulating layer having a high insulating property is interposed between the first insulating layer 23 having a poor insulating property and the metal supporting plate 21. Therefore, the high insulation required for the electrostatic chuck can be obtained, and the strong adsorption performance can be exhibited. In the fourth and fifth embodiments, the periphery of the electrostatic chuck support surface of the metal support plate 21 is formed to have a low step, and the second insulating layer 2 is formed.
The coating with No. 4 covers not only the externally exposed surfaces of the first insulating layer 23 and the third insulating layer 25 but also the entire peripheral side surfaces of the steps of the metallic support plate 21. As a result, the corrosion resistance of the adhesive layer interposed on the fixing surface between the supporting plate 21 and the third insulating layer 25 and the peripheral surface of the supporting plate 21 on the step portion side is also improved.

8 to 11 show a modification of the fourth embodiment. In the modified example shown in FIGS. 8 and 9, not only the peripheral surface of the metal support plate 21 on the step portion side, but also the upper surface portion following the step, or the upper surface portion and the support plate 21.
All side surfaces of the support plate 21 are covered with the second insulating layer 24 to secure the plasma resistance and etching resistance of the support plate 21. In the modified example shown in FIG. 10, instead of the second insulating layer 24, a third insulating layer 25 fixedly provided on the upper surface of the metal supporting plate 21.
The peripheral surface of the support plate 21 on the side of the step portion is covered with. In this case, the third insulating layer 25 is naturally made of a material having excellent corrosion resistance, like the second insulating layer 24. Figure 1
In the modification shown in FIG. 1, the third insulating layer 25 covers the entire peripheral surface of the first insulating layer 23, which is an insulating viscous fluid layer or a gel insulating layer, and further the second insulating layer 24 forms a first insulating layer. The upper surface of the insulating layer 23, the externally exposed surface of the third insulating layer 25, and the step portion side peripheral surface of the support plate 21 are covered. in this case,
The entire circumferential surface of the first insulating layer 23 made of a flexible or fluid gel-like substance or viscous fluid is the second and third insulating layers 2.
Since it is coated with two layers of 4,25, sufficient strength is obtained and durability is also improved.

As is clear from the above description, the electrostatic chuck of the present invention has a basic structure of at least an insulating viscous fluid or a low hardness gel polymer material as an electric insulating layer. Adhesion between the back surface and the holding surface of the electrostatic chuck is increased, and as a result, contact thermal resistance is reduced, and cooling gas or the like for promoting heat transfer is provided between the back surface of the substrate and the electrostatic chuck as in the past. It is possible to obtain a high-performance and highly durable electrostatic chuck having excellent cooling performance that enables highly accurate temperature control of the wafer surface without flowing.

Further, in the present invention, the exposed surface of all insulating layers including the electrical insulating layer made of the viscous fluid or the gel polymer material having a low hardness is covered with a corrosion-resistant protective film such as fluororesin or polyimide resin. May be, in this case, by properly selecting the hardness and elasticity of the electrical insulating layer made of the gel polymer material, the film thickness of the corrosion-resistant protective film,
The plasma resistance can be improved without impairing the cooling characteristics of the substrate, which leads to further improvement in durability.

Further, between the support plate for mounting and fixing the electrostatic chuck and the viscous fluid or gel-like substance having poor insulation property,
When interposing an insulating layer having a normal high insulation property,
Insulation performance required for electrostatic chuck can be secured and strong adsorption can be realized. Further, when the second insulating layer made of a corrosion-resistant insulating layer for covering the externally exposed surface of the electrostatic chuck is covered with the surface of the metal supporting plate around the electrostatic chuck, the supporting plate surface and the third insulating layer are separated from each other. It is possible to improve the corrosion resistance with respect to the adhesive layer existing between and the surface of the supporting plate around the adhesive layer.

The above-mentioned examples specifically explain the representative aspects of the present invention. For example, the materials of the gel polymer material and the corrosion-resistant protective film are not limited to those of the above-mentioned examples, and are equivalent. Any material having the above physical properties can be arbitrarily selected.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an electrostatic chuck device that is a first embodiment of the present invention.

FIG. 2 is a bar diagram showing an experimental result for each contact thermal resistance of an electric insulating layer and another electric insulating layer in the electrostatic chuck of the first embodiment.

FIG. 3 is a schematic configuration diagram of an electrostatic chuck device that is a second and a third embodiment of the present invention.

FIG. 4 is a comparative diagram showing an experimental result for each contact thermal resistance of an electric insulating layer and another electric insulating layer of the electrostatic chuck of the second embodiment.

FIG. 5 is a comparative diagram showing an experimental result with respect to each contact thermal resistance of an electric insulating layer and another electric insulating layer of the electrostatic chuck of the third embodiment.

FIG. 6 is a schematic configuration diagram of an electrostatic chuck that is a fourth embodiment of the present invention.

FIG. 7 is a schematic configuration diagram of an electrostatic chuck that is a fifth embodiment of the present invention.

FIG. 8 is a schematic configuration diagram of an electrostatic chuck showing a modification of the fourth embodiment.

FIG. 9 is a schematic configuration diagram of an electrostatic chuck showing another modification of the fourth embodiment.

FIG. 10 is a schematic configuration diagram of an electrostatic chuck showing still another modification of the fourth embodiment.

FIG. 11 is a schematic configuration diagram of an electrostatic chuck showing still another modified example of the fourth embodiment.

[Explanation of symbols]

10, 20 Electrostatic chuck 11, 21 Metal support plate 12 22 Electrode 13 Electrical insulating layer (made of gel polymer material) 14 Substrate (semiconductor wafer) 15 Lead wire 23 First insulating layer (made of gel polymer material) 24 Second Insulating Layer (Corrosion Resistant Protective Film) 25 Third Insulating Layer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kadoya ▲ Kakuichi             1200 Manda, Hiratsuka-shi, Kanagawa Made by Komatsu Ltd.             Seisakusho Research Headquarters F term (reference) 5F031 HA02 HA03 HA16 HA38 MA32

Claims (7)

[Claims] 1. Electrodes (12, 22) are arranged inside an electric insulating layer (13) fixed on a metal supporting plate (11, 21), and the upper surface of the insulating layer is used as a holding surface of the substrate for electrostatic discharge. In the electrostatic chuck device attracted and held by the above, at least a part of the electric insulating layer covering the electrodes (12, 22) is made of a viscous fluid or a gel substance having a low hardness. 2. The electrostatic chuck device according to claim 1, wherein all of the electric insulating layers are made of a gel material having a low hardness. 3. The electrically insulating layer is composed of at least two layers, and at least one of the inner layers (13, 23) is composed of the viscous fluid or low hardness gel-like material layer, and the outer surface thereof is at least corrosion resistant. The electrostatic chuck device according to claim 1, wherein the electrostatic chuck device is covered with a second insulating layer (24). 4. The electrical insulation layer is composed of at least three layers, and at least one of the inner layers (13, 23) is composed of a viscous fluid layer or a gel material layer of low hardness. The electrostatic chuck device according to claim 3, further comprising a third electrically insulating layer (25) having a high insulating property, disposed between the metal support plate (23, 23) and the metal supporting plate (11, 21). 5. The electrode (12, 22) is the second insulating layer (24)
The electrostatic chuck device according to claim 3, wherein the electrostatic chuck device is arranged on a lower surface of the electrostatic chuck device. 6. The electrode (12, 22) is the third insulating layer (25)
The electrostatic chuck device according to claim 4, wherein the electrostatic chuck device is disposed on the upper surface of the. 7. The second insulating layer (24) is another electrical insulating layer.
The electrostatic chuck device according to claim 3 or 4, wherein the externally exposed surface of the metal support plate (11, 21) around the (13, 23, 25) and the insulating layer (13, 23, 25) is covered. .