JPH11186371A - Bipolar electrostatic chuck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bipolar electrostatic chuck, having a small leakage current at releasing of the voltage, when a body to be sucked is detached. SOLUTION: A pair of electrodes 2a and 2b and an insulating layer 3 provided thereon are provided. A positive voltage is applied on one electrode, and a negative voltage is applied on the other electrode. As a result, in a bipolar electrostatic chuck, which electrostatically sucks the body to be sucked on the insulating layer, the area ratio between the one electrode and the other electrode is made to be in a range of 0.95-1.05.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a semiconductor manufacturing apparatus and the like, and has a pair of electrodes and an insulating layer provided thereon, wherein a positive voltage is applied to one electrode and the other electrode is applied. The present invention relates to a bipolar electrostatic chuck for electrostatically adsorbing an object such as a semiconductor wafer on an insulating layer by applying a negative voltage to the chuck.

[0002]

2. Description of the Related Art In a semiconductor manufacturing apparatus, an electrostatic chuck is used to adsorb and fix a substrate to be processed such as a semiconductor wafer in a reduced-pressure atmosphere. The electrostatic chuck has an electrode and an insulating layer provided thereon, and mounts a substrate to be processed on the insulating layer and supplies power to the electrode, thereby electrostatically charging a substrate to be processed such as a semiconductor wafer. Adsorbs.

[0003] In the electrostatic chuck, depending on the type of electrode,
It is broadly classified into a monopolar electrostatic chuck having a single electrode and a bipolar electrostatic chuck having a pair of electrodes. Among them, the bipolar electrostatic chuck does not need to ground the object to be attracted unlike the monopolar electrostatic chuck, and therefore, the bipolar electrostatic chuck is often used in the semiconductor manufacturing apparatus.

[0004]

However, in the case of the bipolar electrostatic chuck, when the voltage applied to the electrodes for releasing the semiconductor wafer held thereon is released, a leak current is generated. If such leakage current is large, devices formed on the wafer may be damaged.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a bipolar electrostatic chuck having a small leakage current when releasing a voltage when an object to be adsorbed is released.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, the leak current has been reduced by the positive and negative charge amounts induced in the object to be adsorbed when the object is held. Due to the imbalance, if the area ratio between one electrode and the other electrode is set to a specific range close to 1.00, such imbalance between the positive and negative charge amounts is reduced, and the leakage current is reduced. Was found to be small enough to not cause a problem, and the present invention was completed.

That is, the present invention comprises a pair of electrodes and an insulating layer provided thereon, and applies a positive voltage to one of the electrodes and a negative voltage to the other to form an insulating layer. A bipolar electrostatic chuck for electrostatically adsorbing an object to be adsorbed on a layer, wherein an area ratio of one electrode to another electrode is:
A bipolar electrostatic chuck characterized by being in the range of 0.95 to 1.05.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 is a sectional view showing a bipolar electrostatic chuck according to an embodiment of the present invention, FIG.
FIG. 4 is a diagram showing the electrode pattern.

As shown in FIG. 1, a bipolar electrostatic chuck 1
Is configured such that a pair of electrodes 2 a and 2 b are provided between upper and lower insulating layers 3, and is fixed on a base 4.
The electrodes 2a and 2b are made of, for example, copper,
Is made of, for example, ceramics such as alumina or a resin such as polyimide. A DC power supply 5 is connected to the electrodes 2a and 2b, and a negative voltage is applied to the electrode 2a and a positive voltage is applied to the electrode 2b. When power is supplied from the DC power supply 5 to the electrode 2, the semiconductor wafer W, which is the object to be sucked, is placed on the suction surface 3 a of the insulating layer 3 above.
Is electrostatically attracted.

FIG. 2 shows patterns of the electrodes 2a and 2b.
Each of these electrodes 2a and 2b has a substantially semicircular planar pattern, and their area ratio is 0.95 to 0.95.
The range is 1.05. Electrode area ratio is 1.00
However, the area ratio of the electrodes is generally different depending on the shape of the electrostatic chuck, and the area ratio of the electrodes is defined in a very narrow range of 0.95 to 1.05. By doing so, it is possible to reduce the leak current when the voltage is released when the semiconductor wafer W is detached.

That is, when the area ratio is less than 0.95 or more than 1.05, when the semiconductor wafer W is sucked, the imbalance of the positive and negative charges induced on the semiconductor wafer W increases. This imbalance in the amount of electric charge causes a leak current when the wafer leaves the wafer, and this leak current leads to breakage of devices formed on the wafer W. Therefore, by setting the area ratio of these electrodes in the range of 0.95 to 1.05, such an imbalance in charge amount can be reduced, and the leakage current can be reduced to such an extent that device destruction does not pose a problem. can do.

The electrostatic chuck of the present invention is not particularly limited as long as it is a bipolar type, and its shape is not limited as long as the area ratio of the electrodes is within the above range. The material of the insulating layer is desirably the above-described ceramics such as alumina or a resin such as polyimide from the viewpoint of corrosion resistance and the like, but is not limited thereto.

As described above, by applying a positive voltage to one electrode 2b and applying a negative voltage to the other electrode 2a,
In a bipolar electrostatic chuck 1 for electrostatically adsorbing a semiconductor wafer W as an object to be adsorbed on an insulating layer 3, electrodes 2a and 2
By setting the area ratio to b in the range of 0.95 to 1.05, the leak current at the time of leaving the wafer W can be reduced to such an extent that device destruction does not become a problem.

[0014]

Embodiments of the present invention will be described below. A bipolar W electrode having a pattern as shown in FIG. 2 in which the area ratio of the other electrode to one electrode is the value shown in Table 1 is printed on an alumina green sheet, and an alumina green sheet is further pressed thereon. After that, degreasing and firing were performed to produce a bipolar electrostatic chuck. At this time, the size of the electrostatic chuck was 200 mm in diameter and 2 mm in thickness.

The voltage applied to the obtained bipolar electrostatic chuck is ±
After electrostatically attracting an 8-inch wafer at 500 V, the value of the leak current generated when the voltage applied to the electrostatic chuck was released to release the wafer was measured. The results are also shown in Table 1.

[0016]

[Table 1]

As shown in this table, the area ratio of the electrodes is 0.
In Examples 1 to 3 between 95 and 1.05, the leakage current was 1
It became 40 pA or less, and there was no effect on the device.
In Comparative Examples 1 and 2 in which the electrode area ratio was out of the above range, the leak current was 300 pA or more, and it was confirmed that the device formed on the wafer was damaged. From this result, it was confirmed that when the area ratio of the electrodes was within the range of the present invention, the device was prevented from being destroyed by the leak current.

[0018]

As described above, according to the present invention,
The area ratio of the other electrode to one electrode is 0.95
By setting the ratio in the range of 1.05, a bipolar electrostatic chuck having a small leak current when the object to be adsorbed is separated can be obtained. Therefore, the electrostatic chuck according to the present invention can prevent the device from being damaged due to a leak current, and is extremely high in industrial value.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a bipolar electrostatic chuck according to an embodiment of the present invention.

FIG. 2 is a view showing an electrode pattern of the bipolar electrostatic chuck shown in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electrostatic chuck 2a, 2b ... Electrode 3 ... Insulating layer 4 ... Base 5 ... Power supply

Claims (1)

[Claims] 1. A semiconductor device comprising a pair of electrodes and an insulating layer provided thereon, wherein a positive voltage is applied to one electrode and a negative voltage is applied to the other electrode to cover the insulating layer. A bipolar electrostatic chuck for electrostatically adsorbing an adsorbent, wherein an area ratio of one electrode to another electrode is in a range of 0.95 to 1.05.