JP2000208594A - Attraction holding method for glass substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make uniform the substrate temperature and control thereof by providing a glass substrate with a film being attracted by an electrostatic chuck thereby attracting the substrate substantially over the entire surface thereof. SOLUTION: Since an electrostatic chuck can not attract a glass substrate 4 by itself, a film 26 being attracted by the electrostatic chuck 12 is provided on the rear surface of the glass substrate 4, i.e., on the electrostatic chuck 12 side surface. The electrostatic chuck 12 is applied with an attraction voltage from a bipolar output attraction power supply 20 comprising two DC power supplies 22, 24. Consequently, polarization takes place in the attraction film 26 to generate charges of opposite polarity to that of charges on the electrode 16, 18 side in the surface at a part facing the electrode 16, 18 and the attraction film 26 is sucked to the electrostatic chuck 12 by the electrostatic force acting between these charges. Since the attraction film 26 is integral with the glass substrate 4, the glass substrate 4 can be attraction held substantially by the electrostatic chuck 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for holding a glass substrate when performing surface treatment such as ion implantation, ion doping, plasma doping, or ion beam etching in a vacuum, for example, in a vacuum. More specifically, the present invention relates to a method for holding a glass substrate by suction using an electrostatic chuck. The glass substrate is used, for example, for manufacturing a liquid crystal display.

[0002]

2. Description of the Related Art When a silicon substrate or a glass substrate is subjected to an ion beam irradiation, a plasma irradiation or the like in a vacuum to perform the above-described surface treatment, the substrate receives a heat input by the ion beam irradiation or the like and receives a temperature. Rises,
It is necessary to hold the substrate by a method having good cooling performance.

For this reason, when the substrate is a silicon substrate, a method of using an electrostatic chuck to attract and hold the silicon substrate to the substrate is often adopted.

An electrostatic chuck applies a voltage to one or a plurality of electrodes provided in an insulator such as ceramics, and generates positive and negative charges between a substrate as an adsorbent and the electrodes. And the electrostatic force (such as Coulomb force) that works during this time
The substrate is held by suction. For example, see Japanese Utility Model Publication No. Hei 7-26360 and Japanese Patent Laid-Open Publication No. Hei 6-334024.

[0005]

However, when the substrate is a glass substrate, it cannot be adsorbed by an electrostatic chuck. Therefore, conventionally, only a mechanical clamp system for mechanically holding the glass substrate has been used. could not.

[0006] The mechanical clamp method is described in, for example, FIG.
As shown in the example shown in FIG. 1, a method of holding the glass substrate 4 on the support 6 by mechanically pressing the peripheral edge of the glass substrate 4 with an annular substrate holder 10 (the arrow F in the figure indicates the mechanical force) is held. To tell. In this state, the ion beam 2 is applied to the glass substrate 4.
For example, to perform surface treatment. Usually, a rubber-like elastic body 8 is interposed between the glass substrate 4 and the support 6 in order to improve the heat transfer between them.

The reason that a glass substrate cannot be adsorbed by the above-described electrostatic chuck is that glass has molecules connected in a chain and dielectric polarization does not occur even when an electric field is applied thereto. This is considered to be because no electrostatic force is generated between the two.

When the substrate temperature is suppressed to, for example, about 100 ° C., in the mechanical clamp system, the amount of heat that can be given to the substrate is 0 because the heat transfer between the substrate and the support is poor (that is, the cooling performance is poor). It is only about 1 W / cm ² . On the other hand, in the electrostatic chuck method, almost the entire surface of the substrate can be adsorbed, and the heat transfer between the substrate and the electrostatic chuck is good (that is, the cooling performance is good). The amount of heat that can be obtained can be about 0.5 W / cm ² or more. In addition, it is easy to control the temperature of the substrate and to make the substrate temperature uniform.

Accordingly, an object of the present invention is to provide a method capable of holding a glass substrate by suction using an electrostatic chuck.

[0010]

A suction holding method according to the present invention is characterized in that a suction film to be suctioned by an electrostatic chuck is provided on a glass substrate.

According to the above method, the attraction force of the electrostatic chuck does not act on the glass substrate itself, but acts on the attraction film provided on the glass substrate. Therefore, the glass substrate is substantially attracted by the electrostatic chuck. Can be held.

[0012]

FIG. 1 is a diagram showing an example of a suction holding method according to the present invention. In this suction holding method, a suction film 26 to be suctioned by the electrostatic chuck 12 is provided on the glass substrate 4.

The electrostatic chuck 12 is of a bipolar type in this example, and has a structure in which two electrodes 16 and 18 are provided near the surface of an insulator 14 made of ceramics or the like. The electrodes 16 and 18 are, for example, both semicircular, and are embedded in the insulator 14 so that they face each other and form a circle. However, the electrostatic chuck 12 is not limited to a specific structure,
Other structures, for example, one electrode type may be used. The shape of the electrode is not limited to a semicircle, a circle, or the like.

The electrostatic chuck 12 is usually supported by a structure (not shown) cooled by a coolant such as cooling water.
And is forcibly cooled.

The electrostatic chuck 12 has a suction power source 20.
, A voltage for adsorption is applied. The adsorption power supply 20 is of a bipolar output type composed of two DC power supplies 22 and 24 in this example, and has the same value and opposite polarity DC voltages + V and -V.
V and output them to each electrode 1 of the electrostatic chuck 12.
6, 18 respectively.

With the glass substrate 4 alone, as described above,
It cannot be absorbed by the electrostatic chuck 12. Therefore, in this example, the suction film 26 to be sucked by the electrostatic chuck 12 is provided on the back surface of the glass substrate 4, that is, on the surface on the electrostatic chuck 12 side. This adsorption film 26
It is preferably provided at least on the surface facing the electrostatic chuck 12 (more specifically, on the electrodes 16 and 18 thereof), and preferably on the entire surface or almost the entire surface (substantially the entire surface) of the glass substrate 4. More preferred.

More specifically, the attraction film 26 attracted by the electrostatic chuck 12 is, for example, a film that causes dielectric polarization by applying an electric field or a film having conductivity. A multilayer film in which some of these films are combined (for example, in combination with each other or with) may be used.

The thickness of the adsorption film 26 is not particularly limited, and may be, for example, several nm or more. There is no upper limit. In particular,
For example, it may be about several tens nm to several hundreds nm.

In the case where the attraction film 26 is a film that causes dielectric polarization by the above-described electric field application, when the above-described voltage is applied to the electrodes 16 and 18 of the electrostatic chuck 12, for example, a schematic diagram shown in FIG. As described above, polarization occurs in the adsorption film 26, and the surface of the portion facing the electrodes 16 and 18
Charges having polarities opposite to those of the charges on the sides 6 and 18 are generated, and the electrostatic film 12 attracts the attracting film 26 to the electrostatic chuck 12 by electrostatic force acting between these charges. Since the suction film 26 is integrated with the glass substrate 4, the glass substrate 4 is substantially held by the electrostatic chuck 12 by suction.

When the above-mentioned voltage is applied to the electrodes 16 and 18 of the electrostatic chuck 12 when the attraction film 26 is a film having the above-mentioned conductivity, an electric field generated by the voltage causes the electric field in the attraction film 26 to fall. The holes (holes) and the electrons move in opposite directions in the adsorption film 26, and as also schematically shown in FIG. Charges of the opposite polarity to the charges accumulate, and the electrostatic force acting between these charges causes the adsorption film 26
Is attracted to the electrostatic chuck 12. Consequently, the glass substrate 4 integrated with the suction film 26 is substantially held by the electrostatic chuck 12.

In the state where the glass substrate 4 is held by suction on the electrostatic chuck 12 in this manner, the glass substrate 4 is irradiated with, for example, the ion beam 2 as shown in FIG.
The entire surface of the glass substrate 4 can be subjected to a surface treatment such as ion implantation.

The above-described electric field application causes dielectric polarization.
More specifically, for example, a) SiO,
SiO_Two, SiC, Si_ThreeN_Four, TiO_Two, Al_TwoO_Three, Al
N, Ta _TwoO_Five, Ta_TwoN, BaTiO_Three, KTN (KTa_1-x
Nb_xO_Three), PZT (PbZr_1-xTi_xO_Three), BST
｛(Ba, Sr) TiO_Three｝, PLZT (lead, lantern, three
Titanium oxide compound), PbTiO_Three, Y_TwoO_Three, PSG (p
hosphosilicate glass), MnO_Two, ZrO_Two, Poly
Vinylidene fluoride (PVDF), polystyrene, polytetrafluoroethylene
Dielectrics such as ethylene fluoride and polyethylene terephthalate
Membrane, b) Ba (DPM)_Two, Sr (DPM)_Two(DPM is Zipi
Organic film such as baroylmethane).

More specifically, the conductive films shown above include, for example, a) a semiconductor film such as a silicon film and a polycrystalline silicon film (p-Si), b) aluminum, copper,
Metal films such as ITO (indium oxide doped with tin) and the like.

The above-mentioned adsorption film 26 may be embedded in the glass substrate 4, preferably on the side close to the electrostatic chuck 12, as shown in FIG. 3, for example. 4, it may be provided on the surface of the glass substrate 4, that is, on the surface opposite to the electrostatic chuck 12. Even in this case, since the glass substrate 4 does not shield the electric field, the suction film 26 is
Thus, the glass substrate 4 can be adsorbed.

However, as in the example shown in FIG.
Is provided on the back surface of the glass substrate 4, that is, on the surface on the side of the electrostatic chuck 12, so that the suction film 26 can be closer to the electrostatic chuck 12 (more specifically, the electrodes 16 and 18 thereof), so that This is most preferable from the viewpoint of the attraction force because the attraction force can be generated. In addition, even if the adsorption film 26 is provided on the back surface of the glass substrate 4, it does not affect the surface treatment of the glass substrate 4. .

As a method for providing the adsorption film 26 on the glass substrate 4 as described above, for example, plasma CVD
Method, a CVD method such as an optical CVD method, a PVD method such as sputtering, vapor deposition, or ion beam irradiation, a plating method, a method of attaching a thin sheet or plate, and the like.

According to the above-described suction holding method, the following effects can be obtained as compared with the mechanical clamping method in which only the peripheral portion of the substrate is clamped as shown in FIG.

The substantially entire surface of the glass substrate 4 can be attracted by the electrostatic chuck 12 and the heat transfer area between the glass substrate 4 and the electrostatic chuck 12 increases. 12 is improved, and the cooling performance for the glass substrate 4 is improved.

The substantially entire surface of the glass substrate 4 can be attracted by the electrostatic chuck 12 and the thermal resistance between the glass substrate 4 and the electrostatic chuck 12 is reduced, so that the temperature control of the glass substrate 4 is easy. become. More specifically, in the case where the temperature of the glass substrate 4 is controlled by forcibly cooling the electrostatic chuck 12 as described above, the thermal resistance intervening between the two and reducing the controllability is reduced. 4 facilitates the temperature control.

Since the substantially entire surface of the glass substrate 4 can be attracted by the electrostatic chuck 12 and the heat can be removed from the substantially entire surface of the glass substrate 4, the temperature of the glass substrate 4 can be maintained within that surface. It can be made uniform.

Since there is no need to hold down the glass substrate 4 mechanically, contamination (contamination) on the surface of the glass substrate can be prevented. That is,
When the substrate holder is used, particles (dust) are generated due to the contact and rubbing between the glass substrate 4 and the substrate holder, and the ion beam 2 hits the substrate holder to generate sputtered particles. Although contamination occurs due to adhesion to the surface, such contamination can be prevented because the substrate holding method is not required in the above-described suction holding method.

Since it is not necessary to press the substrate to press the peripheral portion of the glass substrate 4, it is necessary to prevent the surface of the glass substrate 4 from having an area where the surface treatment such as ion implantation is not performed due to the substrate press. And the effective use area of the glass substrate 4 increases. As a result, the yield of the glass substrate 4 is improved.

The above-mentioned adsorption film 2 provided on the glass substrate 4
In the case where there is no hindrance even after the desired surface treatment is performed on the glass substrate 4, the adsorbing film 26 may be left as it is. It may be removed later by a removing means such as etching.

Applying a film such as the adsorptive film 26 to a substrate such as the glass substrate 4 or removing the attached film is a process usually performed in the field of semiconductor manufacturing and the like. Can be.

[0035]

As described above, although the glass substrate could not be held by suction using the electrostatic chuck in the past, according to the present invention, the glass substrate is provided with the above-described suction film. The glass substrate can be suction-held by the electrostatic chuck. As a result, the following effects are obtained.

The substantially entire surface of the glass substrate can be adsorbed by the electrostatic chuck, and the heat transfer area between the glass substrate and the electrostatic chuck increases. The transmission is improved, and the cooling performance for the glass substrate is improved.

Since the substantially entire surface of the glass substrate can be attracted by the electrostatic chuck, and the thermal resistance between the glass substrate and the electrostatic chuck decreases, the temperature control of the glass substrate becomes easy.

Since the substantially entire surface of the glass substrate can be attracted by the electrostatic chuck and heat can be removed from the substantially entire surface of the glass substrate, the temperature of the glass substrate can be made uniform within the surface. Can be.

Since there is no need to press the substrate mechanically to press the glass substrate, it is possible to prevent contamination of the glass substrate surface due to the pressing of the substrate.

Since it is not necessary to press the substrate to press the peripheral portion of the glass substrate, it is possible to prevent the area of the surface of the glass substrate from being shaded by the substrate press and not being subjected to surface treatment. The effective use area increases.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a suction holding method according to the present invention.

FIG. 2 is an enlarged view around a glass substrate of FIG. 1;

FIG. 3 is a cross-sectional view showing another example of a mode in which an adsorption film is provided on a glass substrate.

FIG. 4 is a cross-sectional view showing still another example of a mode in which an adsorption film is provided on a glass substrate.

FIG. 5 is a cross-sectional view showing an example of a conventional method of holding a glass substrate by a mechanical clamp method.

[Explanation of symbols]

 2 Ion beam 4 Glass substrate 12 Electrostatic chuck 14 Insulator 16 and 18 Electrode 20 Adsorption power supply 26 Adsorption film

Claims (3)

[Claims] 1. A method for adsorbing and holding a glass substrate by an electrostatic chuck having electrodes provided in an insulator, wherein the glass substrate is provided with an adsorption film to be adsorbed by the electrostatic chuck. To hold glass substrates by suction. 2. The method according to claim 1, wherein the adsorption film is a film that causes dielectric polarization when an electric field is applied. 3. The method according to claim 1, wherein the adsorption film is a film having conductivity.