JP2000156400A - Separating method and separating equipment of substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a separating method and separating equipment of a substrate which can separate a substrate excellently from an electrostatic attracting electrode, while it can be prevented that the substrate jumps or cracks when the substrate of a wafer or the like is pushed up. SOLUTION: Pushing-up pins 5 are protruded a little from the surface of an electrostatic attracting electrode 1 to an electrostatically attracted wafer 4. A load applied to the pins 5 is measured with a load meter 11. The output of a power source is so controlled that the load value is set in a specified range of weight corresponding to the case that the wafer 4 is not electrostatically charged. After the load value has reached the specified range of weight, the wafer 4 is further pushed up by the pins 5 and separated from the electrode 1. As a result, the wafer 4 can be excellently separated from the electrode 1 while it is prevented that the wafer 4 jumps or cracks.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for separating a substrate such as a wafer from an electrostatic chucking electrode.

[0002]

2. Description of the Related Art At present, the line width of a pattern of a semiconductor device is reduced to 0.25 μm or less. In order to obtain a desired pattern shape, it is important to control the temperature of the wafer during the processing. As one of the methods of controlling the temperature of the wafer, there is a method of flowing He gas to the back surface of the wafer that has been electrostatically attracted to cool the wafer, and this method is becoming mainstream.

As shown in FIG. 3, the principle of electrostatic attraction is to form two opposing conductive electrodes 1a and 1b of a comb shape or a spiral type on the surface of an electrostatic attraction electrode (referred to as an ESC electrode) 1 so that a direct current is applied. From the power sources 2 and 3 (see FIG. 2), the conductive electrodes 1a and 1b
By applying positive and negative DC high voltages to the wafer 4, respectively, dielectric polarization (see FIG. 4) occurs in the wafer 4, and the wafer 4 and the ESC electrode 1 are attracted by the Coulomb force due to the electric charge. Then, the wafer 4 attracted to the ESC electrode 1
The temperature of the wafer 4 is controlled by flowing He gas to the back surface of the wafer.

[0004] As shown in FIG. 2, a wafer 4 placed on an ESC electrode 1 is subjected to ESC by electrostatic attraction during processing.
It is adsorbed on the electrode 1. The ESC electrode 1 is provided with a push-up pin 5 that can move back and forth, and the push-up pin 5 is moved up and down by a push-up mechanism 7 provided with a drive motor 6 and the like. After the process is completed, turn off the positive and negative DC high voltages applied from DC power supplies 2 and 3.
Then, the push-up pins 5 are lifted and the wafer 4 is
Lift and separate from C electrode 1. In FIG. 2, reference numeral 8 denotes a control device including a microcomputer for controlling the DC power supplies 2, 3 and the drive motor 6, and the like, and reference numeral 9 denotes a storage device connected to the control device 8.

[0005]

When the positive and negative DC high voltages applied to the ESC electrode 1 are turned off, the wafer 4
Is lost, the Coulomb force is lost and the wafer 4
And the ESC electrode 1 should come off easily. However, in reality, residual charges of dielectric polarization are generated on the wafer 4,
Since the cloning force due to this charge remains, the push-up pin 5
When the wafer 4 is lifted by the
In the worst case, cracking problems have occurred.

As a solution to this, a method is used in which the polarity of the applied voltage is reversed before lifting the wafer 4 and then turned off, or the amplitude is reduced while reversing the polarity like an alternating current and then turned off. However, it was not clear how long and how much voltage should be applied, and there was no other way but to change various conditions and try.

An object of the present invention is to solve the above-mentioned conventional problems, and it is possible to prevent a substrate such as a wafer from jumping or breaking when the substrate is pushed up, and to separate the substrate better from the electrostatic chucking electrode. It is an object of the present invention to provide a method and apparatus for separating a substrate which can be performed.

[0008]

In order to achieve the above object, the present invention provides a method of separating a substrate from an electrostatic chucking electrode, the method comprising: The load acting on the push-up pin is measured with the push-up pin that pushes up the substrate from the suction electrode slightly protruding from the surface of the electrostatic suction electrode, and this load value corresponds to the case where the substrate is not charged with static electricity. The output of the power supply to the electrostatic attraction electrode is controlled so as to be within a predetermined weight range, and after reaching the weight range, the substrate is further pushed up by a push-up pin to be separated from the electrostatic attraction electrode.

According to this, the substrate can be better separated from the electrostatic attraction electrode while preventing the substrate from jumping or breaking at the time of pushing up the substrate.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention according to claim 1 is a method of separating a substrate such as a wafer, which is electrostatically attracted to an electrostatic attraction electrode, from the electrostatic attraction electrode. With the push-up pins that push up the substrate from the surface of the electrostatic chuck electrode slightly protruding from the surface of the electrostatic attraction electrode, the load acting on the push-up pins is measured. To be in the weight range,
The output of the power supply to the electrostatic attraction electrode is controlled, and after reaching the weight range, the substrate is further pushed up by the push-up pin to be separated from the electrostatic attraction electrode.

According to a fourth aspect of the present invention, there is provided a substrate separating apparatus for separating a substrate such as a wafer electrostatically attracted to an electrostatic attraction electrode from the electrostatic attraction electrode, wherein the substrate is pushed up from the electrostatic attraction electrode. A push-up mechanism having a push-up pin;
A load meter that measures the load acting on the push-up pin, and the load acting on the push-up pin is made by slightly projecting the push-up pin from the surface of the electrostatic attraction electrode against the substrate electrostatically attracted to the electrostatic attraction electrode. Control the output of the power supply to the electrostatic attraction electrode so that the load value falls within the weight range corresponding to the case where the substrate is not charged with static electricity, and push up after reaching the weight range. Control means for further pushing up the substrate by means of pins and separating the substrate from the electrostatic chucking electrode.

According to this method and configuration, when the substrate is further pushed up by the push-up pins, the substrate is not charged with static electricity. The substrate can be lifted up and separated better than the electrostatic attraction electrode while preventing the substrate from jumping or cracking.

[0013] The present invention described in claim 2 provides the present invention in claim 1.
In the wafer separation method described above, a load value when the substrate is not charged with static electricity is measured experimentally, and a weight range corresponding to the case where the substrate is not charged with static electricity is measured based on the measured data of the load value. This is set in advance, and according to this method, an accurate weight range can be set.

Hereinafter, an apparatus for separating a substrate according to an embodiment of the present invention will be described with reference to FIG. Note that the same reference numerals are given to those having substantially the same functions as the conventional ones. As shown in FIG. 1, the substrate separating device includes an electrostatic chucking electrode (referred to as an ESC electrode) 1 for electrostatically holding a wafer 4 as a mounted substrate, and a conductive electrode of the ESC electrode 1. DC power supplies 2 and 3 for applying a positive and negative DC high voltage; a push-up mechanism 7 for moving up and down a push-up pin 5 which is provided in the ESC electrode 1 so as to be able to move back and forth; A load cell 11 interposed in 7a for measuring a load acting on the push-up pin 5 and a microcomputer for inputting a signal from the load cell 11 and controlling the DC power supplies 2, 3 and the drive motor 6 of the push-up mechanism 7 And a storage device 13 connected to the control device 12.

In this configuration, when the processing of the wafer 4 is completed and the wafer 4 is separated from the ESC electrode 1, the following control processing operation is performed. First, the control device 12 issues a pin-up command to the drive motor 6 of the push-up mechanism 7 in order to slightly push the push-up pin 5 from the surface of the ESC electrode 1. Then, the load value of the load meter 11 attached to the push-up mechanism 7 is taken into the control device 12. In this state, since the wafer 4 is attracted to the ESC electrode 1, a large load is applied to the push-up pins 5.

As the positive and negative DC high voltages applied to the ESC electrode 1 are reduced, the attraction between the wafer 4 and the ESC electrode 1 decreases, and the value of the load cell 11 also decreases.
Further, the positive and negative DC high voltages are reduced until they have opposite polarities, respectively, so that the value of the load cell 11 falls within a predetermined weight range corresponding to the case where the wafer 4 is not charged with static electricity. Then, when the value of the load cell 11 falls within the predetermined weight range, the positive and negative DC high voltages are returned to 0 V, and then the DC power supplies 2 and 3 are turned off.

Thereafter, the controller 12 further issues a command to raise the pins to the drive motor 6 of the push-up mechanism 7 to lift the wafer 4 from the ESC electrode 1 to a predetermined position.

According to this method and configuration, when the wafer 4 is further pushed up by the push-up pins 5, the wafer 4 has no residual charge and is not charged with static electricity. The wafer 4 can be lifted up and separated better than the electrostatic attraction electrode 1 while preventing the wafer 4 from jumping or cracking without being electrostatically attracted.

The above-mentioned weight range can be determined by simply placing a wafer 4 of the same type in advance on the ESC electrode 1 without applying static electricity, measuring the load value in this state with the load meter 11, and Are obtained by averaging these experimental measurement data, and averaging these experimental measurement data and adopting the average value or a numerical range close to the average value. In this case, with the set weight value being offset, the control process may be performed when the load value becomes zero or the absolute value becomes close to zero.

Instead, immediately before the wafer 4 is electrostatically attracted to the ESC electrode 1, its load value is actually measured by the load meter 11, and after the electrostatic attraction, the load value is adjusted to the above-mentioned value. Alternatively, control may be performed so as to reduce the positive and negative DC high voltages until they have opposite polarities. In this case, it is possible to individually perform control suitable for the weight of the wafer 4. However, in this case, the wafer 4
It is necessary to perform a step of measuring a load before electrostatically adsorbing the ESC electrode 1 on the ESC electrode 1, and thus the processing capacity is improved by adopting the weight range set in advance as described above.

In the above embodiment, the case where the substrate to be separated is the wafer 4 has been described. However, the present invention is not limited to this and can be applied to other substrates such as a glass substrate.

[0022]

As described above, according to the method and apparatus for separating a substrate of the present invention, the push-up pin is slightly projected from the surface of the electrostatic attraction electrode, and the load acting on the push-up pin is measured. The output of the power supply to the electrostatic attraction electrode is controlled so that the load value falls within a predetermined weight range corresponding to a case where the substrate is not charged with static electricity, and after reaching the weight range, the substrate is further pushed up by the push-up pin. By separating the substrate from the electrostatic attraction electrode, the substrate can be better separated from the electrostatic attraction electrode while preventing the substrate from jumping or breaking.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a substrate separation apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a conventional substrate separation apparatus.

FIG. 3 is a diagram showing a configuration of a surface electrode of the electrostatic chucking electrode.

FIG. 4 is a view showing the electrostatic chucking electrode and the dielectric polarization of the wafer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrostatic adsorption electrode 2, 3 DC power supply 4 Wafer (substrate) 5 Push-up pin 11 Load cell 12 Control device 13 Storage device

Claims (5)

[Claims] 1. A method for separating a substrate from an electrostatic attraction electrode, the substrate being electrostatically attracted to the electrostatic attraction electrode, comprising: a push-up pin for pushing up the substrate from the electrostatic attraction electrode; Measure the load acting on the push-up pin while slightly projecting it, and set the load value of the power supply to the electrostatic attraction electrode so that this load value falls within a predetermined weight range corresponding to the case where the substrate is not charged with static electricity. A method of controlling a substrate, wherein the output is controlled, and after reaching the weight range, the substrate is further pushed up by a push-up pin and separated from the electrostatic chucking electrode. 2. A load value when the substrate is not charged with static electricity is measured experimentally, and a weight range corresponding to the case where the substrate is not charged with static electricity is set in advance based on the measured data of the load value. The method for separating a substrate according to claim 1. 3. The method for separating a substrate according to claim 1, wherein the substrate is a wafer. 4. An apparatus for separating a substrate, which separates a substrate electrostatically attracted to an electrostatic chucking electrode from the electrostatic chucking electrode, comprising: a push-up mechanism having a push-up pin for pushing up the substrate from the electrostatic chucking electrode; A load cell that measures the load acting on the substrate and a push-up pin slightly protruding from the surface of the electrostatic attraction electrode to the substrate that is electrostatically attracted to the electrostatic attraction electrode, and the load acting on the push-up pin is measured by the load meter. And control the output of the power supply to the electrostatic attraction electrode so that the load value falls within the weight range corresponding to the case where the substrate is not charged with static electricity. Control means for further pushing up the substrate to separate it from the electrostatic chucking electrode. 5. The apparatus according to claim 4, wherein the substrate is a wafer.