JP2000252351A - Electrostatic chuck and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electrostatic chuck by which a sufficient chucking property is obtained even when an insulating layer is not made extremely thin and in which an adverse effect due to particles is not caused. SOLUTION: This electrostatic chuck 1 is provided with an electrode 2. In addition, the electrostatic chuck is provided with an insulating layer 3 which is formed on the electrode. In the electrostatic chuck, a wafer W is electrostatically attracted to the insulating layer 3 when a voltage is applied to the electrode 2. The thickness of the insulating layer 2 is at 100 to 200 μm, the volume resistivity of the insulating layer is at 1010 to 1013 Ωcm, and the etch rate of the insulating layer by a plasma which contains halogens and/or oxygen is at 1/20 or lower of high-purity quartz glass.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic chuck used for fixing and transporting an object to be adsorbed such as a semiconductor wafer in a semiconductor device manufacturing process or the like, and more particularly to an electrostatic chuck used for plasma containing halogen and / or oxygen. The present invention relates to an electrostatic chuck that is resistant to the above and a manufacturing method thereof.

[0002]

2. Description of the Related Art In the process of manufacturing a semiconductor device, a process of forming a compound film on a semiconductor wafer typified by a silicon wafer or etching is performed by forming an insulating layer on an electrode as a jig for fixing the semiconductor wafer. There is used an electrostatic chuck that has a wafer and electrostatically attracts a wafer onto an insulating layer by applying a voltage to an electrode. And, as the insulating layer, a highly insulating ceramic material such as alumina is being used.

[0003]

However, with a highly insulating material such as alumina, in order to obtain a sufficient adsorption force,
The thickness of the insulating layer needs to be thinner than 0.1 mm, and such an extremely thin insulating layer may be damaged during processing or use.

In addition, since plasma of halogen or oxygen is used for forming and etching the compound film, the use of the electrostatic chuck for a long period of time causes the plasma to corrode the grain boundaries of the insulating layer and drop the particles. However, there is also a problem that the particles become particles and induce device failure.

The present invention has been made in view of the above circumstances, and provides an electrostatic chuck capable of obtaining a sufficient adsorbing property without making the insulating layer extremely thin and having no adverse effects due to particles, and a method of manufacturing the same. The purpose is to do.

[0006]

The present inventors Means for Solving the Problems] As a result of extensive investigations to solve the above problems, a volume resistivity of 10 ^{1 0}
By configuring the insulating layer with a ceramic material having a lower volume resistivity than alumina such as 〜１０10 ¹³ Ωcm,
Adsorption utilizing the Johnsen-Rahbek force becomes possible, and the thickness of the insulating layer is 0.1 mm or more, that is, 100 μm.
It has been found that a sufficient adsorption force can be obtained even at m or more, and that an adverse effect due to particles does not occur when the etching rate of the ceramic material by plasma containing halogen and / or oxygen is 1/20 or less of high-purity quartz glass. Was. Further, they have found that a fluoride of an element selected from alkaline earth metals, rare earth metals, and aluminum is suitable as a ceramic material having such characteristics. Further, it has been found that thermal spraying is suitable for forming an insulating layer of a predetermined thickness using such a fluoride. The present invention has been made based on such findings, and provides the following (1) to (4).

(1) An electrode and an insulating layer provided thereon
By applying a voltage to the electrode,
An electrostatic chuck for electrostatically adsorbing an object to be attracted to
The insulating layer has a thickness of 100 to 200 μm and a volume resistance of
Rate is 10¹⁰-10 ¹³Ωcm, halogen and
High etching rate due to plasma containing oxygen
Ceramic material that is 1/20 or less of pure quartz glass
An electrostatic chuck, comprising:

(2) An electrostatic chuck having an electrode and an insulating layer provided thereon, and applying a voltage to the electrode to electrostatically adsorb the object to be attracted onto the insulating layer, The insulating layer is made of at least one selected from a fluoride of an alkaline earth metal or a rare earth metal, and aluminum fluoride, and has a thickness of 100 to 200 μm.
m, and its volume resistivity is 10 ¹⁰ to 10 ¹³ Ωcm
An electrostatic chuck characterized by the following.

(3) The electrostatic chuck according to (2), wherein the etching rate of the insulating layer by the plasma containing halogen and / or oxygen is 1/20 or less of that of high-purity quartz glass.

(4) An electrostatic chuck for manufacturing an electrostatic chuck having an electrode and an insulating layer provided thereon, and applying a voltage to the electrode to electrostatically adsorb an object to be attracted onto the insulating layer. A method for manufacturing an electric chuck, wherein the insulating layer is formed by spraying at least one particle selected from a fluoride of an alkaline earth metal or a rare earth metal and aluminum fluoride on a substrate on which an electrode is formed. Forming an electrostatic chuck.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The basic structure of an electrostatic chuck to which the present invention is applied includes a monopolar type and a bipolar type. The monopolar type is a type in which opposite voltages are applied to the electrode and the object to be adsorbed, and the bipolar type is one in which opposite voltages are applied to two insulated electrodes to adsorb the object. It is.

The electrostatic chuck according to the present invention is intended for both the monopolar type and the bipolar type.
It is assumed that the electrode has an electrode and an insulating layer provided thereon, and a voltage is applied to the electrode to electrostatically adsorb the object to be adsorbed on the insulating layer. 100
２００200 μm, volume resistivity 10 ¹⁰ -10 ¹³ Ωcm
And an etching rate by plasma containing halogen and / or oxygen is 1/20 or less of that of high-purity quartz glass. This etching rate is determined by performing etching in a plasma having a constant output, measuring the etched thickness at regular time intervals, and measuring the thickness by one.
It is calculated based on the result of performing an arbitrary time up to 0 hours.
Within this range, the etching rate is proportional to time.

Hereinafter, a specific description will be given with reference to the drawings.
1 and 2 are cross-sectional views showing an electrostatic chuck according to an embodiment of the present invention. FIG. 1 shows a monopolar type, and FIG. 2 shows a bipolar type.

The monopolar electrostatic chuck 1 shown in FIG.
An electrode 2 is formed thereon, and an insulating layer 3 is formed thereon. A DC power supply 5 is connected to the electrode 2, and power is supplied from the DC power supply 5 to the electrode 2, so that the semiconductor wafer W, which is the object to be attracted, placed on the suction surface 3 a of the insulating layer 3 is statically charged. Electroadsorbed.

In the bipolar electrostatic chuck 1 ′ shown in FIG. 2, a pair of electrodes 2 a and 2 b are formed on a substrate 4, and an insulating layer 3 is formed thereon. A DC power supply 5 is connected to the electrodes 2a and 2b, and charges of opposite polarities are supplied from the power supply 5 to these electrodes so that the adsorption surface 3 of the upper insulating layer 3 is formed.
The semiconductor wafer W placed on a is electrostatically attracted.

The material of the substrate 4 is not particularly limited as long as it can maintain its shape, such as metal, ceramics, plastic, and a composite thereof. In the case of a monopolar type, the substrate 4 can be used as an electrode if the substrate 4 is a conductive material. In that case, the electrode 2 is unnecessary. FIG. 1 shows an example in which the substrate 4 is an insulating material. Also,
In the case of the bipolar type, if the substrate 4 is an insulating material, FIG.
As shown in (1), the electrodes 2a and 2b can be formed directly on the substrate 4. However, if the material is a conductive material, it is necessary to coat an insulating material on the surface of the substrate and form the electrodes thereon. .

The material of the electrode 2 or the electrodes 2a and 2b is not particularly limited, and a known material such as Cu can be used. The forming method thereof is not particularly limited.
A known method such as thermal spraying can be used.

The insulating layer 3 has a thickness of 100 to 200 μm.
m, a volume resistivity of ^{10 10 ~10 1 3 Ωcm,} the etching rate by the plasma containing halogen and / or oxygen is 1/20 or less of a high-purity quartz glass.

The reason why the thickness of the insulating layer 3 is set to 100 to 200 μm is that if it is less than 100 μm, the durability is too small, and if it is intended to form by processing, it is difficult to process. This is because a sufficient suction force cannot be obtained. Further, the volume resistivity is 10 ¹⁰ to 1
The reason for setting the resistance to 0 ¹³ Ωcm is that charge is relatively easily moved at a volume resistivity in this range, so that charge is induced on the surface of the insulating layer and electrostatically attracted to the charge induced on the object. This is because the force acts, and a high electrostatic attraction force, that is, a Johnsen-Rahbek force can be applied without forming a thin insulating layer.

In the case where the insulating layer is formed of a high insulating material such as alumina as in the prior art, the charge can hardly move because of Coulomb force absorption. Although the thickness of the insulating layer had to be extremely thin, less than 100 μm, the thickness of the insulating layer can be increased to 100 μm or more by applying the Johnsen-Rahbek force as in the present invention.

The reason why the etching rate of the insulating layer 3 by the plasma containing halogen and / or oxygen is set to be 1/20 or less of that of the high-purity quartz glass is that if the etching rate is at such a level, particles will fall off. This is because it is difficult to generate particles. Here, the high-purity quartz glass refers to a glass having a total impurity amount of 10 ppm or less and an alkali metal content of 0.1 ppm or less.

The surface roughness of the insulating layer 3 is 0.1 Ra.
5 μm or less is preferable. When Ra exceeds 0.5 μm,
This is because there is a possibility that a sufficient suction force cannot be obtained.

As a ceramic material which can satisfy the requirement that the volume resistivity is 10 ¹⁰ to 10 ¹³ Ωcm and the etching rate by plasma containing halogen and / or oxygen is 1/20 or less of high-purity quartz glass, Examples include earth metal or rare earth metal fluorides and aluminum fluoride, and ceramics in which aluminum oxide or aluminum nitride is combined with conductive titanium nitride or titanium carbide by 2 to 10%. Preferably, the insulating layer 3 is made of at least one selected from the above-mentioned fluorides.

For alkaline earth metal or rare earth metal fluorides and aluminum fluoride, a plasma containing halogen or oxygen, or both, especially CF ₄
Because of low reactivity with fluorine-based gas plasmas, it is possible to obtain extremely high corrosion resistance with respect to these plasmas such that the etching rate of high-purity quartz glass is 1/20 or less.

Of the fluorides constituting the insulating layer 3,
MgF as fluoride of potassium earth metal₂, CaF₂But
Preferred is a rare earth metal fluoride such as YF₃, C
eF ₃Is preferred.

The insulating layer 3 is formed by vapor deposition, sputtering,
Although it can be formed by a known method such as pasting, it is most preferable to employ thermal spraying when manufacturing a large electrostatic chuck. When the above-mentioned fluoride film is formed by thermal spraying, at least one kind of particles selected from a fluoride of an alkaline earth metal or a rare earth metal, and aluminum fluoride is melted in a high-temperature high-speed gas stream, and the melt is formed. The electrode is attached on the substrate on which the electrode is formed.
The particle size of the fluoride powder as a material for such thermal spraying is 1
It is preferably from 0 to 100 μm, more preferably from 30 to 70 μm. If the particle size is too small, it will be blown off by the gas flow used during thermal spraying, and the torch forming efficiency will be poor. If it is too large, it will not melt sufficiently, and a good film cannot be formed. After forming the insulating layer by thermal spraying as described above, preferably, the surface roughness of the insulating layer is finally adjusted to 0.5 μm or less in Ra by polishing.

According to such a method, the thickness is 100 to 2
It is possible to easily form an insulating layer made of the above-mentioned fluoride having a thickness of 00 μm and a volume resistivity of 10 ¹⁰ to 10 ¹³ Ωcm.

In the electrostatic chuck according to the present invention, the insulating layer 3 has a thickness of 100 to 200 μm and a volume resistivity of 10 ¹⁰ to 10 ¹³ Ωcm as described above.
Due to the Rabbeck force, a sufficient adsorption force can be obtained at 1 kV or less, and the etching rate by plasma containing halogen and / or oxygen is 1/20 that of high-purity quartz glass
Since it has the following excellent corrosion resistance, generation of particles can be reduced.

If the insulating layer is formed of at least one selected from a fluoride of an alkaline earth metal or a rare earth metal and aluminum fluoride, the insulating layer easily has the above-mentioned volume resistivity and corrosion resistance. can do.

[0030]

EXAMPLES Examples of the present invention will be described below in comparison with comparative examples. (Examples 1 to 9) A copper electrode was formed by a thermal spraying method using substrates of φ200 mm of various materials shown in Table 1 and alumina as an inner insulating layer, and further made of the materials shown in Table 1. An insulating layer having the indicated volume resistivity and thickness was formed on the surface by thermal spraying to produce a monopolar or bipolar electrostatic chuck.

A voltage was applied to the electrodes of the electrostatic chuck manufactured as described above, and a silicon wafer having a diameter of 200 mm was sucked. He gas is supplied between the electrostatic chuck and the silicon wafer to be adsorbed to apply pressure, and the He pressure becomes 20.
A voltage indicating an adsorption force that does not leak even at 00 Pa was defined as an adsorption voltage. Further, a CF ₄ gas and an O ₂ gas are supplied in a high frequency electric field of 13.56 MHz and 200 W at a flow rate such that CF ₄ / O ₂ becomes 7/1 to generate plasma, and the amount of corrosion of the electrostatic chuck is increased. And the amount of particles was examined. The etching rate was determined by measuring the sample weight every hour for up to 10 hours after processing, calculating the corrosion thickness from the obtained result and the density of the insulating layer, and using the least squares method per hour. It was calculated as an etching amount. In addition, the measurement of the amount of particles is carried out in the same manner as described above, with the 8-inch silicon wafer being attracted to the electrostatic chuck, plasma treatment being carried out. It was measured with a scattering type particle counter. The number of particles thus measured was divided by the wafer area to calculate the number of particles per unit area.

Table 1 shows the adsorption voltage, the etching rate, and the amount of particles. As shown in this table, Example 1
To 9 are results that are composed of a fluoride insulating layer, CF ₄
Corrosion resistance to gas and O ₂ gas is 0.5 μm or less, which is 1/20 or less of high-purity quartz glass described later,
It was confirmed that the number of particles was extremely small. Also,
Since the volume resistivity is 10 ¹⁰ to 10 ¹³ Ωcm, a sufficient attraction force is obtained at 1 kV or less in the range of 100 to 200 μm for the insulating layer.

(Comparative Examples 1 to 7) As shown in Table 1, the insulating layer was made of high-purity quartz, alumina which was a high-insulating ceramic,
Using a polyimide resin and an insulating layer having a thickness outside the range of the present invention, a monopolar or bipolar electrostatic chuck was manufactured in the same manner as in the example. Then, what kind of adsorption test and corrosion test were performed with the examples.

As a result, as shown in Table 1, since the insulating layer made of high-purity quartz or alumina which is a high-insulating ceramic has a high volume resistivity, the insulating layer has a thickness of 1%.
Even if it is less than 00 μm, 1 k
High voltages above V were required. In addition, the amount of corrosion caused by plasma is large.
The particle size was as large as 7.5 μm, and the particles were therefore large. In addition, since the insulating layer made of polyimide also has a high volume resistivity, an adsorption voltage of 1 kV or less is obtained.
The thickness was 100 μm or less, the amount of corrosion was large, and the amount of particles was large. Although the insulating layer is fluoride,
When the thickness of the insulating layer exceeded 200 μm, the amount of corrosion was small and particles were within an allowable range, but a voltage of 1 kV or more was required to obtain a sufficient adsorption force.

[0035]

[Table 1]

[0036]

According to the present invention, the insulating layer has a thickness
100-200 μm, volume resistivity is 10 ¹⁰-10¹³
Ωcm, which contains halogen and / or oxygen
The etching rate by Zuma is 1/2 that of high-purity quartz glass.
0 or less, so the insulating layer
Sufficient adsorptivity can be obtained without making the
Electrostatic chuck and its
Can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a monopolar electrostatic chuck to which the present invention is applied.

FIG. 2 is a cross-sectional view showing a bipolar electrostatic chuck to which the present invention is applied.

[Explanation of symbols]

 1, 1 '... electrostatic chuck 2, 2a, 2b ... electrode 3 ... insulating layer 3a ... adsorption surface 4 ... substrate 5 ... power supply

 ────────────────────────────────────────────────── ─── Continued on front page (72) Inventor Noboru Miyata 1-2-3 Kiyosumi, Koto-ku, Tokyo Pacific Cement Co., Ltd. Research Term F-term (reference) 5F004 BB12 BB22 BB29 5F031 CA02 HA02 HA03 HA16 MA28 MA32

Claims (4)

[Claims] 1. An electrode and an insulating layer provided on the electrode.
And apply a voltage to the electrode to cover the insulating layer.
An electrostatic chuck for electrostatically adsorbing an adsorbent, wherein the insulating layer has a thickness of 100 to 200 μm and a volume resistance.
Resistance rate is 10¹⁰-10 ¹³Ωcm, halogen and
Etching rate by plasma containing oxygen and / or oxygen
Ceramic material that is 1/20 or less of high purity quartz glass
An electrostatic chuck characterized by being made of a material. 2. An electrostatic chuck, comprising: an electrode; and an insulating layer provided thereon, wherein a voltage is applied to the electrode to electrostatically adsorb the object to be adsorbed on the insulating layer, The insulating layer is made of at least one selected from a fluoride of an alkaline earth metal or a rare earth metal, and aluminum fluoride, and has a thickness of 100 to 200.
μm, and its volume resistivity is 10 ¹⁰ to 10 ¹³ Ωc
m. 3. An etching rate of said insulating layer by plasma containing halogen and / or oxygen is not more than 1/20 of high-purity quartz glass.
2. The electrostatic chuck according to 1. 4. An electrostatic chuck for manufacturing an electrostatic chuck having an electrode and an insulating layer provided thereon, and applying a voltage to the electrode to electrostatically adsorb an object to be attracted onto the insulating layer. A method of manufacturing a chuck, wherein the insulating layer is formed by spraying at least one particle selected from a fluoride of an alkaline earth metal or a rare earth metal, and aluminum fluoride on a substrate on which an electrode is formed. A method of manufacturing an electrostatic chuck, comprising: forming an electrostatic chuck;