JPH0248145A - Electrostatic chuck - Google Patents

Abstract

PURPOSE:To surely perform release of a wafer by providing a driving mean for electrically insulating a piezoelectric element from electrodes for generating electrostatic force on a dielectric and wafer. CONSTITUTION:As a wafer 3 is brought in contact with the dielectric 2 of an electrostatic chuck and voltage is applied between electrodes 1a, 1b by a power supply 6, the wafer 3 is attracted with the electrostatic force. Thus, after the desired processing is applied, the applied voltage is released by the power supply 6. In this state, the wafer is kept to be attracted under polarization generated on the dielectric 2. Next, as voltage is applied on the piezoelectric element 4a by a power supply 7, it is extended so as to receive the release force exceeding the attractive force due to the polarization generated on the dielectric 2, thus surely releasing the wafer from the dielectric 2. As the voltage applied on the piezoelectric element 4a is released, the piezoelectric element 4a is returned in the original length. In this case, the piezoelectric element 4a is electrically insulated from the wafer 3 and electrodes 1a, 2b so that there occurs no trouble even if the voltage is applied on the piezoelectric element 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrostatic chuck that releases a wafer attracted by electrostatic force by a driving means.

[Summary of the Invention 1] The present invention is an electrostatic chuck in which a driving means is provided to ensure that a wafer is detached from a dielectric material.

[Prior Art] As shown in FIGS. 4(A) and 4(B), in a conventional electrostatic chuck, electrodes la and 1b are fixed to a support plate 5 made of an insulator, and electrodes 1a and 1b are mounted on the electrodes 1a and 1b. The insulator is coated and the dielectric 2
A voltage is applied between the electrodes 1a and lb by a power source 6, and the wafer 3 is attracted by the electrostatic force generated at that time.

[Problem to be Solved by the Invention 1] Due to the above structure, even after the voltage applied between the electrodes 1a and 1b is removed, the wafer remains on the dielectric 2 due to the polarization effect generated in the dielectric 2. There was a drawback that the wafer 3 could not be removed because the wafer 3 was adsorbed.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides an electrode that generates an electrostatic force on a dielectric material and a driving means that is electrically insulated from the wafer.

[Effect 1] Since the structure is as described above, according to the present invention, after removing the voltage applied between the electrodes, the wafer being attracted is ,
Drive the driving means to ensure the removal of the wafer,
This greatly improves the operability of electrostatic chucks.

[Example] Embodiments of the present invention will be described below based on the drawings.

FIGS. 1A and 1B are a sectional view and a side view showing a first embodiment of an electrostatic chuck according to the present invention.

A pair of semicircular electrodes 1a, 1b are attached to a support plate 5 electrically insulated from the electrodes 1a, 1b.
A dielectric 2 is formed on a and lb by covering with an insulator. Further, the electrodes 1a and 1b had a hole in which a driving means is arranged, and a piezoelectric element 4a, typified by a piezo element, was arranged in the hole as the driving means. The piezoelectric element 4a
is electrically insulated from the electrodes 1a and 1b, and
The upper surface is coated with an insulator to electrically insulate both the wafer 3 and the dielectric 2 when not driven.
The wafer 3 and the wafer 3 are arranged on the same surface or with a slight gap between them.

Furthermore, a power source 6.7 for applying voltage between the electrodes 1a and 1b and to the piezoelectric element is provided.

Next, its operation will be explained.

When the wafer 3 is brought into contact with the dielectric 2 of the electrostatic chuck and a voltage is applied between the electrodes 1a, 1b by the power source 6, the wafer 3 is attracted by the electrostatic force.

Therefore, after performing the desired treatment, the voltage applied by the power source 6 is removed, but due to the polarization effect generated in the dielectric 2,
The wafer 3 is in a suctioned state.

Next, when a voltage is applied to the piezoelectric element 4a by the power supply 7, the piezoelectric element 4a expands and the dielectric 2
The wafer 3 is reliably separated from the dielectric 2 by applying a detachment force that exceeds the attraction force due to the polarization effect generated in the wafer 3 . When the voltage applied to the piezoelectric element 4a is removed, the piezoelectric element 4a returns to its original length.

Here, the piezoelectric element 4a includes the wafer 3 and the electrodes la, 1b.
Since the piezoelectric element 4a is electrically insulated from the piezoelectric element 4a, no problem will occur even if a voltage is applied to the piezoelectric element 4a. or,
It is also possible to use both the power supply 6 and the power supply 7, and the power supply 7
This can also be achieved with a configuration that removes the .

FIGS. 2(A) and 2(B) are a sectional view and a side view showing a second embodiment of the electrostatic chuck according to the present invention. In this embodiment, a shape memory alloy is used as the driving means.

In this embodiment, as in the first embodiment, electrodes 1a and 1b on which a dielectric material 2 is formed are fixed on a support plate 5, and a shape memory alloy 4b is arranged as a driving means.

The shape memory alloy 4b is electrically insulated from the electrodes 1a, 1b and the wafer 3, and when a voltage is applied from the power source 7, it generates heat and expands, exerting an adsorption force on the wafer 3 due to the polarization effect of the dielectric 2. Applying a detachment force exceeding wafer 3 from dielectric 2
By detaching the wire and removing the voltage, it returns to its original length.

FIGS. 3(A) and 3(B) are a sectional view and a side view showing a third embodiment of the electrostatic chuck according to the present invention.

In this embodiment, a magnetic solenoid is used as the driving means.

In this embodiment, a quarter circular 4
A pair of electrodes 1a and 1b are arranged in which electrodes facing each other with respect to the center have the same potential, and a magnetic solenoid 4C is arranged as a driving means.

In this embodiment, the suction operation of the wafer 3 is the same as in the first embodiment, and the detachment of the wafer 3 is as follows.

After the voltage applied between the electrodes 1a and 1b is removed by the power source 6, a voltage is applied to the magnetic solenoid 4c by the power source 7 to the wafer 3, which is attracted by the polarization effect of the dielectric 2, and the magnetic solenoid 4c stretches, applies a force greater than the adsorption force, and detaches from the wafer 3. After the wafer 3 is removed, the power supply 7 is turned 0FFL, and the magnetic solenoid 4c returns to its original length.

In the embodiments described above, a piezoelectric element represented by a piezo element, a shape memory alloy, and a magnetic solenoid are used as the driving means, but it is also possible to use a motor, a thermal actuator, etc. as the driving means. It goes without saying that there is no problem with the present invention.

Further, the number and shape of electrodes and the number of driving means are not particularly limited to the embodiments of the present invention.

[Effects of the Invention 1] As explained above, according to the present invention, the displacement force of the driving means such as a piezoelectric element, shape memory alloy, magnetic solenoid, etc. is applied to the wafer attracted to the electrostatic chuck. By adding this, it is possible to reliably remove the wafer, and it is possible to provide an electrostatic chuck with excellent operability.

The drive means used in the present invention may be any drive means that generates displacement by electrical or mechanical drive, and is not limited to piezoelectric elements, shape memory alloys, and electromagnetic solenoids. .

[Brief explanation of the drawing]

FIGS. 1A and 1B are a sectional view and a side view showing a first embodiment of an electrostatic chuck according to the present invention, and FIGS.
B) is a cross-sectional view and side view showing the second embodiment of the electrostatic chuck according to the present invention, and FIGS. 3(A) and (B) are cross-sectional views showing the third embodiment of the electrostatic chuck according to the present invention. 4A and 4B are a sectional view and a side view of a conventional electrostatic chuck. 1 a, 2 ・ ・ 3 ・ ・ 4 a ・ 4 b ・ C ・Electrode, dielectric, wafer, piezoelectric element, shape memory alloy Magnetic solenoid 5...Support plate 6...Power source 7 ...Applicant for power supplies and above Seiko Electronics Industries Co., Ltd.

Claims (1)

[Claims] In an electrostatic chuck in which an electrode surface is coated with an insulating material to form a dielectric material, and a wafer placed on the dielectric material is attracted by electrostatic force, a driving means is provided to electrically insulate the electrode and the wafer. An electrostatic chuck, characterized in that the wafer is detached by the driving means.