JP2000183143A - Electrostatic chuck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electrostatic chuck which does not produce warp when it is used in etching treatment and can exhibit high electrostatic attractive force and the size thereof can be made larger. SOLUTION: An insulating layer substrate 2 has a attracting surface 2a for a wafer W and an electrode layer 3 is formed on the opposite surface thereof and the electrode layer formed surface is bonded to a supporting substrate 5 with a bonding agent to construct an electrostatic chuck 1. The insulating layer substrate 2 has a volume resistivity of 108-1013 Ωcm at room temperature, and the supporting substrate 5 consists of substantially the same material as the insulating layer substrate 2, and an insulating spacer 6 is interposed between the insulating layer substrate 2 and the supporting substrate 5.

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 attracted such as a silicon wafer in a semiconductor manufacturing apparatus or the like, and more particularly to an electrostatic chuck having a diameter of 300 mm.
The present invention relates to an electrostatic chuck suitable for a large-diameter wafer.

[0002]

2. Description of the Related Art As a jig for fixing, correcting, or transporting a silicon wafer or the like in a semiconductor manufacturing apparatus or the like, an insulating layer is provided on an electrode, and a wafer is electrostatically attracted to the insulating layer by applying a voltage to the electrode. An electrostatic chuck is used.

In particular, in an etching apparatus or the like, since the wafer temperature is 250 ° C. or less, an electrode is formed on a thin insulating layer substrate made of sapphire or the like, and then the surface on which the electrode is formed is bonded to a ceramic supporting substrate with an adhesive. Is used.

On the other hand, in recent years, the size of electrostatic chucks has been increased with the increase in diameter of silicon wafers. Such a large-sized electrostatic chuck is required to have a high electrostatic attraction force (Coulomb force), and in order to obtain a high electrostatic attraction force by the Coulomb force, the thickness of the insulating layer substrate must be extremely 0.1 mm or less. It must be thin. However, it is extremely difficult to produce a large-sized and thin insulating layer substrate.

[0005] On the other hand, by controlling the volume resistivity of the insulating layer substrate to 10 ⁸ to 10 ¹³ Ωcm, the volume resistivity becomes 1 to 2 Ωcm.
Since a high electrostatic attraction force (Johnsen-Rahbek force) can be obtained even with a thick insulating layer substrate having a thickness of about 10 mm, a large electrostatic capacity is obtained by using such an insulating layer substrate having a volume resistivity of 10 ⁸ to 10 ¹³ Ωcm. Attempts have been made to manufacture chucks.

[0006]

However, in the case of an electrostatic chuck having a structure in which an insulating layer substrate on which electrodes are formed is bonded to a ceramic supporting substrate using an adhesive, the volume resistivity of the insulating layer substrate is 10 ^8. When a material of 〜１０10 ¹³ Ωcm is used, this material has a different thermal expansion coefficient from a ceramic supporting substrate having a volume resistivity of 10 ¹⁵ Ωcm or more.
This difference in the coefficient of thermal expansion causes the electrostatic chuck to be warped.

In order to avoid such a problem, the same material as that of the insulating layer substrate, that is, the volume resistivity of 1 is used as the supporting substrate.
0 ⁸ 10 ¹³ When using the Ωcm material, when the electrode formed on the insulating layer substrate is in contact with the supporting substrate, the electrostatic attraction force, i.e. small current affecting John Sen Rahbek force support There is also a problem that it flows to the substrate side and the electrostatic attraction force is greatly reduced.

On the other hand, in the case of a bipolar electrostatic chuck in which a pair of electrodes are formed on an insulating layer substrate, air bubbles mixed in the adhesive enter between the pair of electrodes when the insulating layer substrate and the ceramic substrate are attached. May cause insulation failure.

The present invention has been made in view of such circumstances, and an electrode is formed on a surface opposite to a suction surface of an insulating layer substrate having a suction surface of an object to be sucked, and the electrode formation surface is bonded. Assuming that the electrostatic chuck has a structure bonded to the supporting substrate with an agent, it does not warp when used in etching processing, etc., can obtain a high electrostatic attraction force, and is capable of responding to enlargement. It is intended to provide a chuck. It is another object of the present invention to provide an electrostatic chuck which does not cause insulation failure between electrodes in the case of the bipolar type.

[0010]

Means for Solving the Problems The inventors of the present invention have repeatedly studied to solve the above-mentioned problems, and as a result, have a volume resistivity of 10 ^{8 or} less.
The problem of warpage that occurs when using an insulating layer substrate of 10 ¹³ Ωcm is solved by using a material that is substantially the same as the insulating layer substrate as the supporting substrate, and the problem of a decrease in the attraction force due to a minute current that occurs at that time. Was found to be solved by providing an insulating spacer between the insulating layer substrate and the supporting substrate. In addition, it has been found that in the case of the bipolar type, by disposing such an insulating spacer between a pair of electrode portions, the problem of poor insulation between the electrode portions is solved.

The present invention has been completed on the basis of such knowledge, and an electrode is formed on a surface opposite to a suction surface of an insulating layer substrate having a suction surface of an object to be sucked, and the electrode is formed. An electrostatic chuck having a structure in which a surface is bonded to a supporting substrate with an adhesive, wherein the insulating layer substrate has a volume resistivity at room temperature of 10 ⁸ to 10 ¹³ Ωcm, and the supporting substrate is formed of the insulating layer substrate. And an insulating spacer is interposed between the insulating layer substrate and the support substrate.

The present invention also provides the above-mentioned electrostatic chuck, wherein the insulating spacer is provided so that an electrode layer formed on the insulating layer substrate does not contact the supporting substrate. Provide a chuck.

Further, according to the present invention, in the above-mentioned electrostatic chuck, the electrode layer has a pair of electrode portions separated from each other, and an insulating spacer is arranged between the pair of electrode portions. Provide an electric chuck.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described specifically. 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 single-pole type electrostatic chuck 1 shown in FIG. 1 includes an insulating layer substrate 2 having a suction surface 2a of a semiconductor wafer W, and an electrode layer 3 is formed below the insulating layer substrate 2. The insulating layer substrate 2 on which the electrode layer 3 is formed is attached to the supporting substrate 5 by the adhesive 4.
And an insulating spacer 6 is interposed between the insulating layer substrate 2 and the support substrate 5. A DC power supply 7 is connected to the electrode 3, and power is supplied from the DC power supply 7 to the electrode 3, so that the semiconductor wafer W, which is the object to be sucked, which is placed on the suction surface 2 a of the insulating layer substrate 2. It is electrostatically attracted.

The bipolar electrostatic chuck 1 'shown in FIG. 2 similarly includes an insulating layer substrate 2 having a suction surface 2a of a semiconductor wafer W, and an electrode layer 3 having a pair of electrode portions 3a and 3b below it. 'Has been formed. The insulating layer substrate 2 on which the electrode layer 3 ′ is formed is fixed to a supporting substrate 5 with an adhesive 4, and an insulating spacer 6 is interposed between the insulating layer substrate 2 and the supporting substrate 5. . The electrode portions 3a and 3b
And an insulating spacer 8 is interposed therebetween. A power source 7 ′ is connected to these electrode portions 3 a and 3 b, and electric charges of opposite polarities are supplied from the power source 7 ′ to these electrodes, and the semiconductor wafer placed on the suction surface 2 a of the insulating layer substrate 2 is mounted. W is electrostatically attracted.

The insulating layer substrate 2 has a volume resistivity at room temperature.
Is 10⁸-10¹³Ωcm material. Absolute
The material of the edge layer substrate 2 has such a volume resistivity.
There is no particular limitation as long as it is performed. For example, TiN is added to AlN.
Sintered with the addition of ₂O₃TiO2₂Add etc.
And reduction sintering, Al₂O₃TiO2₂Add etc.
Reduced and sintered, SiC, ZrO₂, Crystallized glass
And sintered bodies (Adceram) containing calcium silicate
Can be used. In particular, AlN, Si₃N₄To T
Sintered with iN added, Y₂O₃TiO2₂Etc.
Added and reduced and sintered, SiC is halogen-based
Invades zuma (fluorine-based plasma or chlorine-based plasma)
It is particularly preferable because it is difficult to perform.

By using a material having a volume resistivity of 10 ⁸ to 10 ¹³ Ωcm at room temperature as the insulating layer substrate 2, the Johnsen-Rahbek force can be used as the electrostatic attraction force. Even when the thickness of the second wafer 2 is as thick as about 1 to 2 mm, a high electrostatic attraction force can be obtained, and a large electrostatic chuck corresponding to an increase in the size of the semiconductor wafer W can be manufactured.

The support substrate 5 is made of substantially the same material as the insulating layer substrate 2 from the viewpoint of preventing warpage due to a difference in thermal expansion from the insulating layer substrate 2. That is, if they are made of substantially the same material, no difference in thermal expansion occurs, and thus no warpage occurs. In this case, as long as the coefficient of thermal expansion does not change between the insulating layer substrate 2 and the support substrate 5, a slight difference in the amount or composition of the additive is allowed.

The adhesive 4 preferably has a high insulating property with a volume resistivity of 10 ¹⁵ Ωcm or more.
It is preferable that the material be hardly eroded by the plasma such as No. ₄ . For example, a silicone adhesive, a nitrile rubber adhesive, an epoxy adhesive, or the like can be used.

The insulating spacer 6 is provided so that the electrode layer formed on the insulating layer substrate 2 does not contact the supporting substrate 5, and the supporting substrate 5 comes into contact with the electrode layer and a minute current flows through the supporting substrate 5. It has a function to prevent that. The insulating spacer 6 preferably has a high insulating property with a volume resistivity of 10 ¹⁵ Ωcm or more. For example, a fluorine resin, a silicon tape, or the like can be used. The insulating spacer 6 only needs to prevent contact between the electrode layer 3 or 3 ′ of the insulating layer substrate 2 and the supporting substrate 5. Unless the entire surface of the insulating layer substrate 2 is covered, the spacing and thickness of the insulating spacer 6 are Not specified. If the insulating spacer 6 covers the entire surface of the insulating layer substrate 2, the insulating layer substrate 2 and the supporting substrate 5 cannot be stuck with an adhesive.

The insulating spacer 8 has a function of preventing insulation failure in the bipolar electrostatic chuck 1 'shown in FIG. That is, the bubbles mixed in the adhesive 4 cause the electrode portions 3a and 3b in the bipolar electrode layer 3 '.
If the insulating spacer 8 is arranged in this manner, insulation failure between electrodes will not occur even if bubbles are mixed in the adhesive 4. As the insulating spacer 8, a fluorine resin, a silicon tape, or the like can be used as in the case of the insulating spacer 6.

In the case of the bipolar electrostatic chuck 1 ', the thickness of the insulating layer substrate 2 is desirably not more than half the distance between the electrode portions. When the thickness of the insulating layer substrate 2 exceeds の of the distance between the electrode portions, the minute current flowing through the semiconductor wafer W decreases, and the electrostatic attraction force decreases.

When the RF electrode for generating plasma is arranged below the electrostatic chuck, the thickness of the electrostatic chuck is desirably 10 mm or less. If it exceeds 10 mm, the impedance of the electrostatic chuck becomes high, and it becomes difficult to generate plasma.

In the electrostatic chuck configured as described above, when the power is supplied to the electrode layer 3 or 3 ′ from the power supply 7 or 7 ′, the semiconductor wafer W is placed on the suction surface of the insulating layer substrate 2 by the electrostatic suction force. Adsorbed. At this time, since the insulating layer substrate 2 is made of a material having a volume resistivity of 10 ⁸ to 10 ¹³ Ωcm, the semiconductor wafer W is attracted by the Johnsen-Rahbek force.

In this case, since the support substrate 5 is formed of substantially the same material as the insulating layer substrate 2, for example, due to a difference in thermal expansion between the insulating layer substrate 2 and the support substrate 5 during the etching process, the static expansion occurs. Since the electric chuck does not warp and the insulating spacers 6 are provided, the contact between the support substrate 5 and the electrode layers 3 and 3 ′ is prevented, and the volume resistivity is 10 ⁸ to 10 ^{8 which} is the same as that of the insulating layer substrate 2. It is possible to prevent a small current from flowing into the support substrate 5 formed of a material of 10 ¹³ Ωcm, and to reduce the electrostatic attraction force.

Therefore, the semiconductor chuck W can be attracted by the Johnsen-Rahbek force with a high attraction force without warping by the electrostatic chuck having the above structure, so that the insulating layer substrate 2 has a thickness of about 1 to 2 mm. The thickness can be increased, and a large-sized electrostatic chuck can be manufactured corresponding to an increase in the size of the semiconductor wafer W.

Further, since the insulating spacer 8 is provided between the electrode portions 3a and 3b in the bipolar electrostatic chuck 1 ', poor insulation between the electrode portions 3a and 3b even if bubbles are mixed in the adhesive 4. Can be prevented from occurring.

[0029]

Embodiments of the present invention will be described below. (First Embodiment) After forming a monopolar electrode layer on the insulating layer substrate shown in Table 1 by Cu plating and attaching a fluororesin tape as an insulating spacer on the surface on which the electrode layer was formed, the results are shown in Table 1. The supporting substrate of the combination shown was attached with a silicone adhesive to produce an electrostatic chuck. The shape of the insulating layer substrate and the supporting substrate was 400 mm in diameter and 2 mm in thickness, and the shape of the fluororesin tape was 10 mm in width and 0.1 mm in thickness. For comparison, an electrostatic chuck without an insulating spacer was also manufactured.

[0030]

[Table 1]

The obtained monopolar electrostatic chuck was irradiated with plasma (power: 5 W / cm ² ), and the warpage of the electrostatic chuck at that time was visually observed. In addition, the voltage 500
After applying V to attract the wafer to the electrostatic chuck, He gas was flowed between the electrostatic chuck and the wafer, and the He pressure when the He gas leaked was defined as the electrostatic attraction force. Table 2 shows the results.

[0032]

[Table 2]

As shown in Table 2, when the insulating layer substrate and the support substrate were made of the same material, the electrostatic chuck did not warp even when irradiated with plasma because the thermal expansion coefficients were the same. However, when the materials differed from each other (Examples 1 to 5 and Comparative Examples 2 and 3), when the thermal expansion coefficients were different, the electrostatic chuck was warped by plasma irradiation (Comparative Example 1).

Further, when the insulating spacer is not inserted, the electrode layer formed on the insulating layer substrate comes into contact with the supporting substrate, and a minute current also flows on the supporting substrate side. It was about half (Comparative Examples 2 and 3).

(Second Embodiment) Here, a bipolar Cu electrode layer is formed on a ZrO ₂ insulating layer substrate, and a fluororesin tape is used as an insulating spacer between a pair of electrode portions of the bipolar electrode layer and the insulating layer. After being attached to another portion between the substrate and the support substrate, ten electrostatic chucks were prepared in which the support substrate (ZrO ₂ substrate) was attached with a nitrile rubber adhesive. In addition, ten insulating chucks were manufactured in which insulating spacers were attached to other portions without providing insulating spacers between electrode portions.

A voltage of 10 kV was applied to the obtained bipolar electrostatic chuck to evaluate whether or not dielectric breakdown occurs between the electrodes.
As a result, when an insulating spacer was stuck between the bipolar electrodes, no dielectric breakdown was observed between the electrodes. However, when an insulating spacer was stuck between the electrode portions, dielectric breakdown was observed in two out of ten electrodes. Was done. Examination of the electrostatic chuck with the dielectric breakdown showed that air bubbles were mixed between the electrodes.

[0037]

According to the present invention, there is provided a structure in which an electrode layer forming surface of an insulating layer substrate having a volume resistivity of 10 ⁸ to 10 ¹³ Ωcm at room temperature is bonded to a supporting substrate with an adhesive, and the supporting substrate is Since it is made of substantially the same material as the insulating layer substrate and the insulating spacer is interposed between the insulating layer substrate and the supporting substrate, there is no warpage when used for an etching process or the like, and high electrostatic attraction. A force can be obtained, and an electrostatic chuck that can cope with an increase in size 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 ... insulating layer substrate 2a ... adsorption surface 3, 3' ... electrode layer 3a, 3b ... electrode portion 4 ... adhesive 5 ... support substrate 6, 8 ... Insulating spacer 7 Power supply

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Chiharu Wada 1-5-9 Kimi no Mori Higashi, Togane-shi, Chiba F-term (reference) 5F031 CA02 HA02 HA03 HA16 MA29 MA32 PA13 PA16

Claims (3)

[Claims] 1. An electrostatic layer having a structure in which an electrode layer is formed on a surface opposite to a suction surface of an insulating layer substrate having a suction surface of an object to be sucked, and the electrode layer formation surface is bonded to a support substrate with an adhesive. An electric chuck, wherein the insulating layer substrate has a volume resistivity at room temperature of 10 ⁸ to 10.
¹³ Ωcm, wherein the supporting substrate is made of substantially the same material as the insulating layer substrate, and an insulating spacer is interposed between the insulating layer substrate and the supporting substrate. . 2. The electrostatic chuck according to claim 1, wherein the insulating spacer is provided such that an electrode layer formed on the insulating layer substrate does not contact the support substrate. 3. The electrostatic chuck according to claim 1, wherein the electrode layer has a pair of electrode parts separated from each other, and an insulating spacer is disposed between the pair of electrode parts.