JPH1167883A - Electrostatic chuck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily remove an attracted body in a short time while ability for securely attracting and holding it is maintained by supplying applied voltage in pulse. SOLUTION: Voltage is applied to an electrode 2 in an insulating body 1 and an object 4 is attracted on the insulating body 1 for holding. Here, a power source 3 supplies applied voltage in pulse. Applied pulse voltage can arbitrarily set the interval and voltage and it executes adjustment for arbitrarily giving the holding force of the object 4 or adding remaining charge. For attracting the object 4, high voltage is applied. The interval of applied pulse voltage is adjusted so that residual charge becomes small and holding force can sufficiently be maintained. Thus, the object 4 can securely be attracted and held, and it can easily and stably be removed in a short time.

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 an electrostatic chuck which applies a voltage to an electrode in an insulator, adsorbs an object on the insulator, and holds the object. In particular, the present invention provides an electrostatic chuck capable of easily detaching an object to be detached when the object is detached. The present invention can be widely used when electrostatically adsorbing and holding an object to be adsorbed on an insulator,
In particular, for example, it can be preferably applied as an electrostatic chuck for supporting a wafer or the like by suction in the manufacture of a semiconductor device.

[0002]

2. Description of the Related Art Conventionally, when an object to be sucked is sucked and held by an electrostatic chuck, the object to be sucked may not be stably and easily released when the object to be sucked is separated. This problem will be described below, taking as an example a case where a wafer is suction-supported by an electrostatic chuck. For example, when processing such as etching (dry etching such as plasma etching) or film formation (plasma CVD or the like), a semiconductor wafer is suction-supported by an electrostatic chuck, and is separated after processing.

Conventionally, when a voltage is applied to an electrode in an insulator and a wafer is attracted by using an electrostatic chuck that attracts an object to be attracted onto the insulator, the applied voltage is sufficient for the wafer. Set the voltage to obtain the appropriate suction force. At the time of holding and holding the wafer, the applied voltage set as described above is maintained. When the wafer is detached, the applied voltage is set to zero or a reverse voltage is applied to detach the wafer. Specifically, for example, as shown in FIG. 3, a voltage of 500 V is applied as a sufficiently high voltage for suction and holding, and during the wafer suction and holding, this constant voltage is applied, and the wafer is held. At the time of separation, the applied voltage is set to 0V.

[0004] However, even if the applied voltage is reduced to zero, the charge induced in the insulator and the wafer remains, and this residual charge makes it difficult to detach the wafer, thereby requiring a long detachment time. is there.

In addition, even if a reverse voltage is applied at the time of detachment, detachment of the wafer is not stabilized, and a trouble accompanying this may occur.

Japanese Patent Laid-Open Publication No. Hei 8-64664 discloses that in order to release a wafer with a minimum force, a gas leak rate between a wafer and a chuck is determined (by obtaining an electrostatic potential at which the leak amount exceeds a certain value). Although a method of determining an optimum chuck opening voltage for canceling the residual charge is described, the calculation is complicated and cannot be said to be a technique that can be easily embodied. Further, specifically, it seems that a method of gradually decreasing the chuck voltage is employed, and it is not always clear whether or not the wafer can be easily detached with a short detaching time.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and maintains the performance of reliably sucking and holding an object to be sucked such as a wafer while removing the object. An object of the present invention is to provide an electrostatic chuck that can easily and stably perform this in a short time.

[0008]

In order to achieve the above object, an electrostatic chuck according to the present invention applies a voltage to an electrode in an insulator, adsorbs an object to be adsorbed on the insulator, and holds the object. Wherein the applied voltage can be supplied in a pulsed manner.

As described above, according to the present invention, since the applied voltage can be supplied in a pulsed manner, the detachment can be easily and stably performed even when the object to be attracted such as a wafer is detached. Withdrawal time is also short. For example, when adsorbing the object to be adsorbed, a constant voltage of, for example, a high voltage is applied to perform the adsorption, and then, for example, a pulse-like applied voltage is supplied while considering the residual charge so as to hold the object to be adsorbed. Then
The residual charge can be reduced while maintaining sufficient suction and holding of the object to be sucked such as a wafer, and the object to be sucked such as a wafer can be easily and stably detached. Japanese Patent Application Laid-Open No. 63-139634 describes a method in which a pulse is generated by comparing an applied voltage with a reference voltage and the quality of the power supply wiring is checked by applying the pulse. This is different from the method of the present invention in which the supply of the pulse is pulsed. Japanese Patent Application Laid-Open No. Hei 8-64664 discloses a measurement of a pulse generated between a wafer and a chuck, but this does not indicate that the applied voltage itself is pulsed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. However, needless to say, the present invention is not limited by the embodiments described below.

Embodiment 1 In this embodiment, as an example, the present invention is applied to a monopolar electrostatic chuck used for suction and support of a semiconductor wafer. As shown in FIG. 1, the electrostatic chuck of the present embodiment applies a voltage to an electrode 2 in an insulator 1 to adsorb an object 4 (here, a wafer) on the insulator 1, This is maintained. Reference numeral 3 denotes a power supply for supplying an applied voltage. In this example, the applied voltage can be supplied in a pulsed manner, and the interval and voltage of the pulsed applied voltage can be arbitrarily set. Thereby, the holding force of the object 4 (wafer) can be arbitrarily obtained. Further, the interval and voltage of the pulse-like applied voltage can be adjusted in consideration of the residual charge.

FIG. 2 shows an applied voltage in the present embodiment. FIG. 2 shows the state of voltage application with the applied voltage on the vertical axis and time on the horizontal axis (the same applies to FIG. 3).

As shown in FIG. 2, in the present embodiment, a high voltage (500 V in the figure) is applied when the wafer as the object to be sucked 4 is sucked, and
Is adsorbed.

Thereafter, a pulse-like voltage is applied in consideration of the residual charge, and the object 4 (wafer) is held. By applying a pulsed voltage in this manner, the object 4
The conventional residual charge is reduced while maintaining the secure suction and holding of the (wafer). Therefore, this makes it easy to detach the object 4 (wafer) (here, the applied voltage is 0 V as shown in FIG. 2). In this example, the residual charge is reduced, and the interval of the pulse-like applied voltage is adjusted so that the holding power can be sufficiently maintained.
In some cases, the applied voltage can be adjusted to an optimum state. In any case, assuming that the residual charge is small (preferably minimum) or a value close to the optimum value, the residual charge is added so as to make small (preferably minimum) the predicted residual charge. Control is performed.

According to the present embodiment, the wafer as the object to be sucked 4 can be reliably sucked and held, and the wafer can be easily separated, so that the time for separating the wafer can be reduced. That is, in the conventional example, as shown in FIG. 3, the applied voltage is a constant voltage during the wafer chucking and holding, and the voltage is 0 V when the wafer is detached. In the present embodiment, a voltage is applied to the electrode 2 in the insulator 1 and the object 4
When a wafer is sucked, a voltage is applied in a pulsed manner, so that the object to be sucked 4 (wafer) is securely sucked and held, and the object to be sucked 4 (wafer) is easily absorbed.
Can be detached, thereby making it possible to shorten the time for detaching the to-be-adsorbed body 4 (wafer).

[0016]

As described above, according to the present invention,
A voltage is applied to the electrodes in the insulator to adsorb the object to be adsorbed on the insulator, and in an electrostatic chuck that holds the object, while maintaining the performance of reliably adsorbing and holding the object to be adsorbed such as a wafer, When the object to be adsorbed is detached, the effect is obtained that it can be easily and stably performed in a short time.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an outline of an electrostatic chuck (single-electrode electrostatic chuck) used in an embodiment of the present invention.

FIG. 2 is a diagram showing a state of an applied voltage in the first embodiment of the present invention.

FIG. 3 is a diagram showing a state of an applied voltage in the related art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Insulator, 2 ... Electrode, 3 ... Power supply (pulse supply of an applied voltage is possible), 4 ... Adsorbent (wafer).

Claims (3)

[Claims] 1. An electrostatic chuck for applying a voltage to an electrode in an insulator to adsorb an object to be adsorbed on the insulator and holding the same, wherein the applied voltage can be supplied in a pulsed manner. Electrostatic chuck. 2. The electrostatic chuck according to claim 1, wherein a constant voltage is applied when the object to be attracted is attracted, and then a pulse-like applied voltage is supplied to hold the object to be attracted. . 3. The electrostatic chuck according to claim 1, wherein an interval and a voltage of the pulsed applied voltage can be arbitrarily set.