JPS6094247A - Electrostatic chuck - Google Patents

Abstract

PURPOSE:To correct the warping of a chucked object to support fixedly said object it by forming an electrode disposed on the back side of a dielectric adsorbing the chucked object and having a partial space in the plane along the surface of a chuck. CONSTITUTION:An electrode 11 is constituted from a central circular portion 11a, two ring portions 11b, 11c concentrically surrounding said portion 11a and a connecting portion 11d connecting said portion 11a to said portions 11b, 11c. And the electrode 11 is attached to the surface of a base plate 14 made of ceramics and a dielectric 12 formed of a glass plate is bonded to the electrode 11. Then, assuming the outer diameter D of the electrode 11 is 120mm. and the diameter of the central circular portion 11a is 30mm. for example, the widths lof the ring-like electrodes 11b, 11c and adjacent space A are made equal to each other. When a wafer 13 is mounted on the surface of the dielectric 12 and potential difference is given between the electrode 11 and the wafer 13, the warping of the wafer 13 to lift the central portion for example can be corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industry] 111 Field of the Invention The present invention relates to an electrostatic chuck, and particularly to an electrostatic chuck for chucks such as semiconductor wafers, which may be warped in their natural state (hereinafter referred to as wafers). This invention relates to an electrostatic chuck for correcting (7) a material (7) into a predetermined shape such as a flat shape, and then supporting and fixing the material.

[Prior art]

Conventionally, this type of electrostatic chuck consists of: - As shown in FIG. A DC power source 4 is connected between the wafer 3 placed on the surface (hereinafter referred to as the chuck surface) and the electrode 1, and an attractive force is generated by the potential difference between the two, so that the wafer 3 is placed on the chuck surface. The attraction force f of this electrostatic chuck is expressed by the following formula.

where, K is a constant, n is the permittivity of dielectric 2, and ■ is electrode 1.
potential difference between and wafer 3, a (is the thickness of dielectric 2, l)
is the gap between the dielectric 2 and the wafer 3.

As is clear from the above equation, the attraction force is between electrode I and wafer 3.
The smaller the gap 1) between the Therefore, as shown in Figure 2, if Ueno 3' is curved so that the outside is higher than the medium heat (although there is no problem,
As shown in the figure, if the center is curved higher, the periphery is in contact with the chuck surface or is close to the chuck surface, so it receives a stronger suction force, and this periphery is suctioned and fixed first. I'm going to try it. Medium heat part of Weno 3 (good, then,
It tries to stick to the chuck surface due to the suction force, but because this center part descends and comes into close contact with the chuck surface (
The surrounding part moves outward F,) fJ: <<.

However, this peripheral portion is already in close contact with the chuck surface as shown in R+2. The sea urchin is able to slide because it is under a stronger suction force, so the sea urchin/・
The center portion of the wafer 3 cannot be brought into close contact with the chuck surface, and the warpage of the wafer 3 cannot be completely straightened. According to the experiments of the inventor of the present application, as mentioned above, the center of the wafer 3 is high.
In this case, as shown in FIG.
If the wafer 3 is made smaller so that it faces only the center
We have confirmed that it is possible to remove the warpage and chuck in a more completely straightened state, but this type of electrostatic chuck (
As shown in FIG. 4, it is impossible to correct the warpage of the wafer 3' which is warped so that the outer side is higher. In addition, in FIG. 3 and FIG. 4, 4 is a board|substrate.

[Purpose of the invention]

An object of the present invention is to eliminate the above-mentioned drawbacks, and to more completely correct the warpage and support and fix the object to be chucked, such as a wafer, even if it is warped in any direction in its natural state as described above. Our goal is to provide electrostatic chucks that can

[Structure of the invention]

In order to achieve this object, the present invention does not provide an electrode so as to cover the entire surface of the chuck facing the object to be chucked, but instead provides a blank space along the chuck surface where the electrode does not exist partially. This type of electrode configuration allows for more complete correction of curvature, not only when the outer edges are highly curved, but also when the center is curved high. can.

〔Example〕

5 and 6 showing one embodiment of the present invention will be explained below. Figure 5 (shows the shape of one electrode II,
It consists of a medium-heat circular part ++a, two ring parts 11b and IIc surrounding it in a circular shape, and a connecting part +1d that connects them to each other.The electrode II made on such a putter 7 is the sixth As shown in the figure, 471 layers are attached to the surface of a ceramic substrate 14. A dielectric material 12 made of a glass plate is pasted (1) to the negative end of the electrode 11 by an adhesive method. Note that l b icV'l[4', pole 1
(,) 1iiJ note'
1 (L life 11 no Yu 1 diameter 1) LK l 20+? 1m
, the diameter c1 of the central circular part 1 is 30, and the ring-shaped electrodes 1N'(l Il), 11 t: :F, and the width t of the blank part A adjacent to these (see Figure 5) are They are distributed equally to each other.

Dielectric body 12 of the electrostatic chuck configured as described above
A wafer 1 with a diameter of 125 mm is placed on the 0 surface, that is, on the chuck surface.
A potential difference of 400 V was applied between the electrode (1) and the wafer I3.
The height difference of the wafer 13, which had been warped so that the center of m was higher, was reduced to about 5 μm, and it was confirmed that the warp had been sufficiently corrected. As shown in FIG. 1, in the case of an electrostatic chuck in which the electrode I covered the entire chuck surface, the height difference was about 15 μm.

Further, it goes without saying that according to the electrostatic chuck of the present invention, it is possible to completely correct the warpage more easily than in the wafer 13 shown in FIG. 6, which is warped in the opposite direction.

Figures 7 through 9 show different examples of electrode patterns by 7'L, Figure 7 (with -i connection part), Figures 8 and 9 with 7'L different electrode patterns. Electrodes 31 and 41 are shown which are made up of a plurality of radially extending protrusions 31a or 41a.

In addition, in the electrode pattern described above, the density is l'i < at the center of the electrode, and it becomes lower at the periphery (see Figure 9).
In this way, the warp can be more accurately corrected when the center is high.

〔Effect of the invention〕

As described above, according to the present invention, the electrode pattern 7 is formed so as to partially have a blank part in the plane along the chuck surface, so that the electrode pattern 7 is warped so that the outer side is higher.
It is possible to more completely correct the warpage of both an object to be chucked, such as an object to be chucked, such as an object to be chucked, and an object to be chucked, such as an object to be chucked, which is warped so that the center thereof is higher, and to support and fix the object.

[Brief explanation of the drawing]

Figures 1 and 2 are schematic sectional views showing the relationship between a conventional electrostatic chuck and an object to be chucked, and Figures 3 and 4 are diagrams showing the electrostatic chuck used in the experiment and the object to be chucked. FIG. 5 is a plan view showing an example of the electrode pattern of the electrostatic chuck according to the present invention, and FIG. 7 to 9 are plan views showing examples of different electrode patterns of the electrostatic chuck according to the present invention. 1, l 1.2+, 31.41...electrode, 2.1
2... Dielectric, 3.3', 13... Object to be chucked, 4.14... Substrate, 15... Lead wire. Applicant: Toshiba Machine Co., Ltd., District 1, 2nd figure, 5th figure, 7th figure, 8th figure, 9th figure. , Person making the amendment Patent applicant 104 Address 4-4, Ginza 4-chome, Seriku 11-4, Tozen Chuo-ku, "Detailed Description of the Invention" column b of the specification subject to the amendment Contents of the amendment 1) [1 Specification 4 lines from the bottom of page 2

Claims (1)

[Scope of Claims] 1. In an electrostatic chuck consisting of a dielectric material formed of an insulator and which attracts an object to be chucked onto a 7La surface, and an electrode disposed on the back side of the dielectric material, the electrode is placed on the chuck surface. An electrostatic chuck is formed with a partial blank space along/in the plane and has a 7 and ':x'l'f feature. 2. An electrostatic chuck with a C-turn in a substantially concentric shape including a ring. The electrostatic chuck 0 according to claim 1, wherein the electrode is formed in a pattern of a plurality of protrusions extending substantially radially, and the electrode is formed in a pattern of 7L.Claim 1. 4. The electrostatic chuck according to claim 1, 2 or 3, wherein the electrode is formed such that the density IW is high in the medium heat part and low in the peripheral part. Electric chuck.