JPH11168132A - Electrostatic adsorption device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain sufficient attractive force with respect to acceleration on transferring, and at the same time, to reduce a foreign object adhering onto the rear of a wafer, and to prevent the contamination of the wafer. SOLUTION: A support member which is in contact with a wafer as a retainer is an electrostatic attraction device consisting of an electrostatic attraction pad. In the device, the electrostatic attraction pad is constituted of an arm 2 made of a material that is softer than the wafer, an insulating dielectric 3 and 6 which is incorporated into the soft arm 2 and exposed only at a plurality of parts that are the local parts of the arm 2, and electrode plates 3 and 6 overlapped with the insulating dielectrics 3 and 6.

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 a method for transporting or processing a sample or a work (hereinafter simply referred to as a sample) to be subjected to fine processing such as a conductor or a semiconductor such as a silicon wafer. And a device for fixing and holding the sample.

[0002]

2. Description of the Related Art When a sample such as a silicon wafer (hereinafter simply referred to as "wafer"), which is an object to be processed, is subjected to fine processing such as etching or sputtering, the sample is processed at a high speed in a vacuum in order to increase productivity. Requires a fixed holding device for transporting the device inside the device. Conventionally, as a sample holding means for such an application, a sample holding device using electrostatic suction, which can be used even in a vacuum and can generate a suction force on the entire back surface of the wafer, a so-called electrostatic chuck has been used. I have.

In the electrostatic chuck, since the surface of the sample and the surface of the chuck are in direct contact with each other, foreign matter adheres to the back surface of the wafer as the sample. An electrostatic chuck for reducing such contamination on the back surface of the wafer is disclosed in, for example, JP-A-6-291175.

The electrostatic chuck described in Japanese Patent Application Laid-Open No. 6-291175 is provided with an internal electrode on a single-crystal sapphire plate and forms an adsorption surface for adsorbing a sample on the surface of the plate to form a static state. This constitutes an electric chuck. According to this electrostatic chuck, there is an effect that leakage current is small, mechanical strength is excellent, high suction force is obtained, and an object to be sucked such as a silicon wafer is hardly contaminated.

[0005] Further, as an apparatus capable of keeping a surface facing a wafer always smooth without polishing, for example, an apparatus described in Japanese Patent Application Laid-Open No. Hei 7-130828 is known. The invention described in this publication discloses a dry etching apparatus having a mounting table for fixing a wafer by electrostatic attraction and a plasma CVD (Chemical Vapor Depth).
related to semiconductor devices such as
An upper surface of a mounting table on which a wafer is mounted and subjected to surface treatment is coated with a polymer film having a high dielectric constant and containing no metal.

[0006]

When a sample, for example, a semiconductor wafer is held by an electrostatic chuck, foreign matter adheres to the contact surface with the wafer at the following two points. First, the first is wafer shaving due to surface roughness projections of the electrostatic chuck component. The material of the electrostatic chuck is often made of ceramics, which is a hard material, and because it is made by sintering, the wafer is shaved by minute projections on the surface, and the shavings may become adhered foreign substances .

The second is transfer of foreign matter on the chuck surface to a sample by the action of an electric field. In some cases, minute foreign matters that adhere to the chuck surface and cannot be removed even by cleaning are transferred to the wafer by the action of an electric field. These foreign substances may be as many as thousands in the case of an 8-inch semiconductor wafer, for example. These foreign substances transfer to adjacent wafer surfaces in a wafer cassette, a load lock chamber of a manufacturing apparatus, or the like during the progress of the process, and are very likely to cause a defect.

However, Japanese Patent Application Laid-Open No. 6-291175 describes the above.
In the electrostatic chuck described in Japanese Patent Application Laid-Open Publication No. H11-163, the point that a foreign material of a heavy metal substance which causes metal contamination in a semiconductor manufacturing process is not attached and a material containing no heavy metal substance, that is, a single crystal sapphire is considered. However, no consideration was given to reducing the number of foreign substances.

In the semiconductor manufacturing apparatus described in Japanese Patent Application Laid-Open No. Hei 7-130828, the entire electrostatic attraction surface is covered with a coating of a polymer film having a high dielectric constant and containing no metal. It is. This apparatus is used for a wafer loading electrode in a plasma processing apparatus or the like, and is suitable when the wafer does not come off during processing, that is, when the suction force is only moderate.

The polymer film is interposed in the gap between the object to be adsorbed and the adsorption surface because the dielectric constant of the gap is set to be as large as possible.
This is considered to prevent a decrease in the attraction force. However, there is a difference in the dielectric constant between the ceramic and the polymer forming the electrostatic attraction surface of several tens to one hundred times, which is considered to be the same as the fact that there is a space. In a case where a supporting member that comes into contact with a wafer is a transfer arm in an electrostatic chucking device that holds the wafer by electrostatic suction when the wafer is transferred or processed, the electrostatic chuck is accelerated during transfer. Need sufficient suction power to overcome
In the semiconductor manufacturing apparatus described in Japanese Patent Application Laid-Open No. Hei 7-130828, no consideration has been given to an attraction force sufficient to overcome acceleration during transport.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art. It is an object of the present invention to provide an electrostatic chuck with a sufficient chucking force with respect to acceleration during transportation when holding a sample. It is an object of the present invention to provide a highly reliable electrostatic adsorption device which can maintain foreign objects and reduce foreign substances adhering to the back surface of a sample and prevent contamination of the sample.

[0012]

Means for Solving the Problems In order to achieve the above object, the configuration of the first means of the electrostatic chuck according to the present invention is as follows.
In an electrostatic chuck that holds a sample by electrostatic chuck when the sample is transported or processed, a support member that comes into contact with the sample as a main body of the electrostatic chuck is a member made of a material softer than the sample. And an electrostatic attraction pad which is incorporated into the member made of this soft material and comprises an insulating dielectric exposed only at a plurality of local portions of the member and a conductive electrode plate superposed on the insulating dielectric. It is comprised by these. Here, the support member that comes into contact with the sample is formed of a resin material.

According to another aspect of the present invention, there is provided an electrostatic attraction device according to the present invention, wherein an electrostatic chuck for holding a sample by electrostatic attraction when transporting or processing the sample. In the suction device, a support member that comes into contact with the sample as a main body of the electrostatic suction device is incorporated into an insulating dielectric member having an uneven surface and a concave portion on the surface of the insulating dielectric member. And a member made of a material softer than the sample, and an electrostatic attracting portion composed of a conductive electrode plate superimposed on the rear surface side of the convex portion of the insulating dielectric. Here, the member incorporated in the concave portion of the insulating dielectric is formed of a resin material or a resin-based thin film.

That is, the object of the present invention is to form an arm of a support member constituting an apparatus main body from a resin material, for example, polyimide, and to use a pad of an electrostatic chuck (electrostatic suction pad) having a smaller surface area than the arm of the apparatus main body. ) Is incorporated in the arm. The material of the electrostatic chuck at the local portion of the arm is ceramics of a hard material, but since the contact area with a sample, for example, a semiconductor wafer, is reduced, the wafer may be scraped due to projections of the surface roughness of the ceramics. In addition, transfer of foreign matter due to the action of an electric field can be minimized.

Further, since the resin material constituting the arm is a softer material than the silicon wafer, there is no abrasion of the wafer due to surface roughness projections. In particular, if a resin material such as polyimide is made of a hard material, the arm itself is hard to be worn, so that the effect of reducing foreign matter adhesion can be obtained.

Further, if the electrostatic chuck portion of the surface of the arm of the apparatus body facing the sample is set slightly lower, it is possible to reduce the area of the portion that is actually in contact, and Since the portion is made of a resin material to which foreign matter adheres less than the electrostatic chuck portion, the effect of reducing foreign matter can be further achieved. In this case, however, the size of the difference between the electrostatic chuck portion and the arm of the apparatus main body is set to a small size that does not lose the electrostatic chucking effect, and preferably about 0.1 mm or less.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. [Embodiment 1] FIG. 1 is a front view of an electrostatic attraction device showing a first embodiment of the present invention, and FIG. 2 is a cross-sectional view of the device of FIG. 1 and 2, reference numeral 1 denotes a semiconductor wafer (hereinafter simply referred to as a wafer) which is a sample fixed and held;
Is a support member related to the main body of the holding device when carrying the wafer, and in this embodiment, is an arm (hereinafter, referred to as an arm) attached to the tip of the transfer robot. The arm 2 is desirably formed of a relatively hard resin material such as polyimide.

3, 4, 5, and 6 are insulating dielectrics and 3 ', 4
', 5', and 6 'are conductive electrode plates provided so as to be superposed on the insulating dielectrics 3, 4, 5, and 6, respectively. 3 ', 4', 5
'And 6' constitute an electrostatic attraction pad for attracting the wafer 1 by static electricity. The material of the insulating dielectrics 3, 4, 5, and 6 is ceramics, which is a hard material. 7 is a power supply for supplying a voltage to the electrostatic chuck pad, 8 is a switch,
9 is a lead wire for supplying voltage, and 10 is a ground.

In the electrostatic chuck (electrostatic chuck) configured as described above, when the switch 8 is turned on and a voltage is applied to each of the suction pads, the wafer 1 is acted upon by static electricity.
Is sucked and fixed to the electrostatic suction pad surface 11. As a result, the rotational motion, linear motion,
The wafer 1 can be transferred without shifting even in a high-speed operation such as vertical movement.

In this case, at least one of the electrostatic attraction pads arranged at four local portions of the arm 2 needs to have a polarity opposite to that of the other pads, whereby a bipolar electrostatic attraction device can be constructed. . Desirably, since the potential of the wafer 1 can be set to the same potential as the ground 10, it is preferable that the areas of the pads of the positive polarity and the negative polarity are the same. In addition, a monopolar electrostatic attraction device can be configured by using at least one pad with a conductive material. In this case, it is desirable that the area of the pad of the conductive material be as small as possible.

In general, in an ordinary electrostatic chucking device (electrostatic chuck), the supporting member itself of the holding device main body is made of an insulating dielectric over the entire area corresponding to the arm 2 in this example, and the electrostatic chuck is used. The force is acting. As described above, the dielectric material used for the electrostatic chuck is ceramics, which is a hard material, and is often made by sintering. The wafer was shaved by the minute burrs and the like, and the shavings became attached foreign matter, and foreign matter on the chuck surface due to the action of an electric field was transferred to the back surface of the wafer and contaminated.

On the other hand, in the present embodiment, by embedding the electrostatic attraction pad in the arm 2, the hard material of the insulating dielectrics 3, 4, 5, and 6 on the wafer 1 and the electrostatic attraction pad surface 11 is used. The contact area with certain ceramics can be reduced,
Shaving of the wafer 1 due to protrusions of the surface roughness of the ceramics and transfer of foreign matter due to the action of an electric field can be minimized. Therefore, it is desirable that the total area of the electrostatic suction pad surface 11 be as small as possible within a range in which a required suction force can be secured.

In addition to the surface 11 of the electrostatic attraction pad, the arm 2, which is another contact portion with which the wafer 1 is in contact, is made of a resin material softer than a silicon wafer, for example, polyimide. As a result, the wafer 1 is not scraped by the projections and dust generation is reduced. In particular, if a hard material is used among resin materials such as polyimide, the arm 2 itself is also hard to be worn, so that the effect of further reducing foreign matter adhesion can be obtained.

[Embodiment 2] FIG. 3 is a cross-sectional view of an electrostatic chuck according to a second embodiment of the present invention. In the figure, components having the same reference numerals as those in FIG. 2 are the same as those in the first embodiment, and the description thereof will be omitted. The cross-sectional view of FIG. 3 in the second embodiment corresponds to the cross-sectional view of FIG. 2 in the first embodiment, and a front view thereof is not shown, but the shape of the support member conforms to FIG. Things.

In FIG. 3, reference numeral 12 denotes an insulating dielectric made of, for example, ceramics having irregularities on its surface;
Is a resin material (hereinafter referred to as a resin body) embedded so as to be embedded in the concave portion of the insulating dielectric 12. The resin body 14 is, for example, polyimide, and may be formed of a resin-based thin film. Reference numeral 13 denotes a conductive electrode plate.
Numeral 3 is provided so as to be superimposed on the rear surface side of the convex portion 15 of the insulating dielectric 12.

In the electrostatic chuck shown in FIG. 3, the main body (support member) of the sample holding device is made of an insulating dielectric material 12 having an uneven surface, and is opposite to the surface holding the wafer 1. A conductive electrode plate 13 is provided on the side surface. Further, an arm of the transfer robot is configured by incorporating a resin body 14 of another material into the concave portion of the insulating dielectric 12.

In the electrostatic chuck (electrostatic chuck) configured as described above, the switch 8 is turned on and the electrode plate 1 is turned on.
3, the wafer 1 is attracted and fixed to the surface of the convex portion 15 of the insulating dielectric 12 by the action of static electricity. Also in this case, at least one of the plurality of electrodes needs to have a polarity opposite to that of the other electrodes, whereby a bipolar electrostatic chucking device can be configured. Similarly to the first embodiment, since the wafer 1 can be desirably set to the same potential as the ground 10, it is preferable that the areas of the positive and negative electrodes are the same.

In this embodiment, the resin body 14 is incorporated into the concave portion of the insulating dielectric 12 so that the contact area between the wafer 1 and the ceramic material, which is a hard material, of the convex portion 15 of the insulating dielectric 12 is formed. And the transfer of foreign substances due to the action of an electric field can be minimized. It is desirable that the surface area of the convex portion 15 of the insulating dielectric 12 is small.

In addition to the electrostatic attraction portion, the resin body 14, which is another contact portion with which the wafer 1 is in contact, is made of a resin material softer than the silicon wafer, for example, polyimide. As a result, the wafer 1 is not scraped and dust generation is reduced. In particular, if a hard material among resin materials such as polyimide is used for the resin body 14,
Since it is hard to wear itself, the effect of reducing the adhesion of foreign substances can be further obtained.

[Embodiment 3] FIG. 4 is a cross-sectional view of an electrostatic chuck according to a third embodiment of the present invention. In the figure, components having the same reference numerals as those in FIG. 3 are the same as those in the second embodiment, and the description thereof will be omitted. The cross-sectional view of FIG. 4 in the third embodiment corresponds to the cross-sectional view of FIG. 2 in the first embodiment, and a front view thereof is not shown, but the shape of the support member conforms to FIG. Things.

In the electrostatic chuck shown in FIG.
The polarity of the voltage to be supplied to the electrode is the same, and at least one conductive material 16 is provided. The conductive material 16 is brought into contact with the wafer 1 to have a polarity opposite to that of the electrode plate 13, so that a monopolar type is provided. It is also possible to configure an electrostatic suction device. Also in this case, it is desirable that the contact area of the conductive material 16 with the wafer 1 is as small as possible. According to the third embodiment, the same effects as in the second embodiment can be obtained.

[Embodiment 4] FIG. 5 is a front view of an electrostatic chuck according to a fourth embodiment of the present invention.
6 is a cross-sectional view of the device of FIG. In the figure, components having the same reference numerals as those in FIGS. 1 and 2 are the same as those in the first embodiment, and the description thereof will be omitted. 5 and 6, 18, 1
9 is an insulating dielectric, 18 'and 19' are insulating dielectrics 1
8 and 19 are electrically conductive plates superimposed on the insulating dielectrics 18 and 19 and the electrode plates 18 'and 1 respectively.
At 9 ', an electrostatic attraction pad for attracting the wafer 1 by static electricity is formed. The material of the insulating dielectrics 18 and 19 is ceramics which is a hard material.

In the electrostatic chuck shown in FIGS. 5 and 6, the electrostatic chuck pad surface 11 is set slightly lower than the wafer contact surface 2a of the arm 2. s indicates the size of the difference between the electrostatic suction pad surface 11 and the wafer contact surface 2a of the arm 2. The dimension s is set to a slight step where the electrostatic attraction effect is not lost, preferably about 0.1 mm or less.

In the electrostatic chuck (electrostatic chuck) configured as described above, the switch 8 is turned on and the electrode plate 1 is turned on.
By applying a voltage to 8 'and 19', a suction force acts on the wafer 1 from the electrostatic suction pad surface 11, and the wafer 1 is pressed and fixed to the resin portion of the arm 2. In the present embodiment, since the surface 11 of the electrostatic attraction pad is set slightly smaller than the wafer contact surface 2a of the arm 2 by a dimension s, the portion in contact with the wafer 1 becomes the wafer contact surface 2a.

That is, the insulating dielectrics 18 and 19 of the electrostatic attraction pad made of ceramics as a hard material can attract and hold the wafer 1 without directly contacting the wafer 1. Dust generation can be further reduced as compared with the embodiment. In order to reduce the area of direct contact with the wafer 1 and increase the electrostatic attraction force as much as possible, the surface area of the insulating dielectrics 18 and 19 of the electrostatic attraction pad is increased, and the arm, which is a resin portion, is formed. It is desirable to reduce the area of the second wafer contact surface 2a.

Although the present embodiment has been described with the same configuration as that of the first embodiment, the configuration of the second embodiment is also different from that of the first embodiment in that the convex portion 15 of the insulating dielectric 12 shown in FIG. By setting it slightly lower than the surface of the resin body 14,
Similar effects can be obtained. In each of the above embodiments, the case where the sample to be transferred or processed is a semiconductor wafer has been described. However, the present invention is not limited to a wafer, and other objects may be used within a range in which a similar effect is expected. It can be applied to the sample of the above.

[0037]

As described above in detail, according to the present invention, when a sample is held by an electrostatic chuck, a sufficient suction force is maintained against acceleration during transportation and the sample adheres to the back surface of the sample. It is possible to provide a highly-reliable electrostatic adsorption device that can reduce the amount of foreign matter that is generated and prevent contamination of the sample.

[Brief description of the drawings]

FIG. 1 is a front view of an electrostatic chuck according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the device of FIG.

FIG. 3 is a cross-sectional view of an electrostatic chuck according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view of an electrostatic chuck according to a third embodiment of the present invention.

FIG. 5 is a front view of an electrostatic chuck according to a fourth embodiment of the present invention.

6 is a cross-sectional view of the device of FIG.

[Explanation of symbols]

1 ... wafer, 2 ... arm, 2a ... wafer contact surface, 3,
4, 5, 6, 12, 18, 19 ... insulating dielectric, 3 ',
4 ', 5', 6 ', 13, 18', 19 '... electrode plate, 7
... Power supply, 8 ... Switch, 11 ... Electrostatic suction pad surface, 1
4 ... resin body, 15 ... convex part, 16 ... conductive material.

Claims (5)

[Claims] 1. An electrostatic attraction device for holding a sample by electrostatic attraction when transporting or processing the sample, wherein a supporting member that comes into contact with the sample as a main body of the electrostatic attraction device is softer than the sample. And a conductive electrode plate superimposed on the insulating dielectric, which is incorporated in the soft material and is exposed only to a plurality of local portions of the member. And an electrostatic attraction pad. 2. The electrostatic attraction device according to claim 1, wherein the support member in contact with the sample is formed of a resin material. 3. An electrostatic attraction device for holding a sample by electrostatic attraction when transporting or processing the sample, wherein a support member that comes into contact with the sample as a main body of the electrostatic attraction device has an uneven surface. An insulating dielectric member having: a member made of a material softer than the sample and incorporated into a concave portion on the surface of the insulating dielectric member; and a back surface side of the convex portion of the insulating dielectric. And a conductive electrode plate superimposed on the device. 4. The electrostatic chuck according to claim 3, wherein the member incorporated in the concave portion of the insulating dielectric is formed of a resin material or a resin-based thin film. . 5. The electrostatic attraction unit according to claim 1, wherein a surface of the electrostatic attraction unit is slightly lower than a surface of the support member that contacts the sample, the surface being in contact with the sample. An electrostatic attraction device characterized by being set.