Patent Application
20080055813
The embodiments will be described in detail with reference to the following drawings, in which like reference numerals refer to like elements, and wherein:
Hereinafter, a preferred embodiment according to the present invention will be described in detail with reference to the drawings. Throughout the drawings, like reference numerals are used to designate like elements.
As shown in
The AC power supply 129 is used to supply AC power to the electrode 124 after processing steps have been completed and it is time to remove the substrate S from the chuck 122. In a first embodiment, when it is time to remove the substrate from the chuck 122, the supply of DC power from the DC power supply 127 is cut off and simultaneously the AC power supply 129 is activated to supply the AC power to the electrode 124.
In some embodiments, the AC power supply 129 may be an AC voltage supply or an AC pulse generator. The AC power supply 129 may be selectively used depending on the properties of any residual electric charge which remains in the electrostatic chuck after the DC power supply has been cut off.
If the DC power 127 supply had applied a positive DC voltage to the chuck during the substrate processing steps, and then AC power, where the voltage switches back and forth between negative and positive, is applied to the electrode 124 of the chuck 122 after the processing steps are complete, any residual positive charge left from the application of the positive DC voltage will quickly dissipate. Similarly, if the DC power supply 127 had applied a negative DC voltage to the electrode 124 of the chuck 122 during the processing steps, application of an AC voltage to the electrode 124 will quickly dissipate any residual negative charge remaining on the electrode 124. That is, the applied AC power causes any residual electric charge remaining in the electrostatic chuck 122 to be neutralized. This, in turn, eliminates any residual electrostatic force tending to hold the substrate on the chuck 122. Thus, the substrate S can be easily and safely detached from the electrostatic chuck 122, eliminating the problem of breakage which could be caused by a residual attractive force.
As can be seen in
In some embodiments, a voltage sensor, or more generally, an electric charge detecting sensor 131, can be used to detect a residual electric charge left on the electrode of the chuck. Detecting the residual electric charge with the sensor 131 prevents more power than is necessary from being supplied by the AC power supply. Instead, the sensor 131 is used to adjust the amount of AC power applied by the AC power supply 129 so that only the AC voltage required to neutralize the remaining residual electric charge is applied to the electrode 124 when the DC power supply 127 is shut off.
The sensor 131 may also be used to confirm whether the electrode is completely neutralized as the AC power is supplied. If the residual charge on the electrode 124 is not neutralized, additional AC power can be supplied through the AC power supply 129 to neutralize the electrode 124.
Embodiments of the electrostatic chuck 122 may further include a control unit (not shown) for controlling the DC power supply 127 and the AC power supply 129. As described above, when a process of electrostatically adsorbing a substrate is terminated, the control unit would cut off the DC power and simultaneously operate the AC power supply 129 to supply the AC power to the electrode to eliminate any residual electric charge. The control unit would rapidly decrease the amplitude of the AC power supplied from the AC power supply 129 to rapidly eliminate the residual electric charge remaining on the chuck 122.
The sensor 131 can be grounded via a first switch 133. The switch would control the grounded and non-grounded states of the multi-tester. The switch 133 could also be used to ground the electrode, which would be another way of reducing or neutralizing any residual charge on the electrode 124. Grounding could be used instead of the above-described method in which AC power is supplied through the AC power supply 129 after the DC power is cut off. The grounding method and/or the method of using the AC power supply 129 may be selectively or concurrently used, as desirable.
In addition, the power supply line 128 running to the electrode 124 could be provided with a second switch 135. The second switch 135 would be used to control the application of the DC power and the AC power to the electrode 124. For example, when the electrostatic holding force is to be generated, the AC power supply 129 may be cut off so that only the DC power supply 127 supplies DC power to the electrode. When it is desirable to neutralize the electrostatic holding force, the second switch 135 could supply the AC power from the AC power supply 129 and the DC power supply 127 may be cut off. Further, when it is desirable to supply both DC and AC power together, the second switch 135 can serve to adjust the amplitude of the supplied power.
When it is time to remove the electrostatic holding force, the second switch 135 can be used together with the first switch 133 to eliminate some or all of the residual electric charge on the chuck 122 by grounding the electrode 124 before the AC power supply 129 supplies AC power. This allows some or all of the residual electric charge to be reduced naturally, without the need to supply artificial AC electric power.
A method of using the processing apparatus shown in
Steps S300 and S400 are optional. Thus, in some embodiments, the method may proceed from step S200 directly to step S500. Further, in some embodiments, only step S400 may be skipped. In other words, in some embodiments, the detection step may be performed, and then the method could proceed directly to step S500. Finally, in some embodiments, the detecting step may not be performed. In other words, the method may proceed from step S200 directly to step S400.
Step S300 of detecting the electric charge can be used as a part of a method for adjusting the electric charge of the AC power supplied to neutralize the remaining electric charge in step S500. That is, the remaining electric charge is exactly detected by means of a sensor, so that only the AC power required to neutralize the remaining electric charge is supplied, thereby preventing unnecessary power consumption.
In an electrostatic chuck as described above, when the DC power is cut off, any residual electric charge on the chuck can be quickly eliminated by applying AC power to the chuck. Thus, the time required to eliminate the residual electric charge from an electrostatic chuck so that the substrate can be safely removed is considerably reduced.
Any reference in this specification to “one embodiment,” “an embodiment,” “example embodiment,” etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other ones of the embodiments.
Although a number of illustrative embodiments have been described, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements which would fall within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2006-0083013 | Aug 2006 | KR | national |
