JP3006502B2 - Plasma processing apparatus and plasma processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus and a plasma processing method, and more particularly to a plasma processing apparatus and a plasma processing method for easily peeling off a wafer which is attracted to a lower electrode by electrostatic force during plasma processing. About.

[0002]

2. Description of the Related Art In a conventional plasma processing apparatus, as disclosed in Japanese Patent Application Laid-Open No. 5-283379, for example, when a wafer is electrostatically suctioned, a transfer error due to residual suction force after the plasma processing is solved. A method is used in which a high-frequency power smaller than that during etching is applied to the same electrode as during etching.

FIG. 3 is a structural view showing a conventional plasma processing apparatus. As shown in FIG. 3, an upper electrode 3 and a lower electrode 4 are provided in the chamber 1, and a wafer 8 is disposed on the lower electrode 4. A high-frequency power source 7 is connected to the lower electrode 4 via a matching unit 6. The upper electrode 3 is grounded, high-frequency power is applied to the lower electrode 4, and high-frequency discharge is performed between the upper electrode 3 and the lower electrode 4. To cause plasma processing.

After the plasma processing, when the push-up mechanism 9 is lifted to lift the wafer 8, the wafer 8 is attracted to the lower electrode 4 by electrostatic force, and the wafer jumps to cause a displacement.

Therefore, after the plasma processing, 1/6 high-frequency power during the plasma processing is applied to the lower electrode 4 to eliminate static electricity. Thereafter, the push-up mechanism 9 moves up and the wafer 8
Was lifted, and the wafer 8 was unloaded by the transfer mechanism.

[0006]

In the plasma processing apparatus shown in FIG. 3, when plasma processing is performed, plasma ions and electrons are generated in the chamber 1, and the plasma ions are generally heavier than the electrons and have the property of being difficult to move. is there. As in the conventional example shown in FIG. 3, when the high frequency power for static elimination is supplied to the lower electrode 4 with the upper electrode 3 grounded in the same manner as in the plasma processing, the upper electrode 3 is grounded. , Plasma ions gather on the upper electrode 3 side,
There are many electrons on the wafer 8 side, and it is not possible to generate ions that cancel the electrostatic force adsorbing the wafer 8 to the lower electrode 4. Therefore, even if the above-described high-frequency power for static elimination is applied, , Still the wafer 8 is the lower electrode 4
Is attracted by electrostatic force.

Therefore, when the wafer 8 is lifted from the lower electrode 4 by the push-up mechanism 9, the electrostatic force is overcome and the wafer 8 is forcibly lifted. There is a problem that a mistake occurs in the conveyance.

An object of the present invention is to provide a plasma processing apparatus and a plasma processing method for removing an electrostatic force that causes a wafer to be attracted to a lower electrode after the plasma processing.

[0009]

In order to achieve the above object, a plasma processing apparatus according to the present invention has a changeover switch and a high-frequency power supply, and generates a high-frequency discharge between an upper electrode and a lower electrode to generate a lower-frequency discharge. A plasma processing apparatus for performing plasma processing on a wafer on an electrode, wherein a changeover switch and a high-frequency power supply are operated when the wafer is separated from the lower electrode after the plasma processing, and the changeover switch grounds the lower electrode. Side to ground.
The high-frequency power supply is connected to the upper electrode by the changeover switch and supplies high-frequency power for static elimination to the upper electrode.

[0010] Further, the plasma processing method according to the present invention comprises:
A plasma processing method having a plasma process and a static elimination process, wherein the plasma process supplies high-frequency power to a lower electrode, grounds an upper electrode, and performs a plasma process on a wafer installed on the lower electrode. Yes, static elimination processing
After the plasma processing of the wafer, the lower electrode is grounded, and high-frequency power is supplied to the upper electrode to perform a static elimination process.

Further, the high-frequency power supplied during the static elimination process is set to be smaller than the high-frequency power supplied during the plasma process.

[0012]

The lower electrode to which high-frequency power has been applied during plasma processing is separated from the high-frequency power supply, the lower electrode is grounded, and low-frequency high-frequency power is applied to the upper electrode on which no wafer is installed.

The wafer placed on the lower electrode coated with an insulator is polarized due to the ion sheath generated by the plasma processing, and is attracted to the lower electrode by electrostatic force. When high frequency power is applied from the upper electrode side in this state, sufficient positive ions are supplied to the wafer,
The polarization of the wafer is relaxed, the electrostatic force between the wafer and the lower electrode is weakened, and the wafer can be easily pushed up by the pushing-up mechanism.

[0014]

Next, an embodiment of the present invention will be described in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a configuration diagram showing Embodiment 1 of the present invention.

In FIG. 1, an insulator 4 is placed in a chamber 1.
The lower electrode 4 coated with a and the upper electrode 3 are provided facing each other, and the wafer 8 is arranged on the lower electrode 4. The lower electrode 4 is connected to a lower high-frequency power source 7 via a changeover switch 12 and a lower matching device 6, and the upper electrode 3 is connected to a lower switch 4 and an upper matching device 10 via a matching device 10. The upper-side high-frequency power supply 11 is connected. 9 is a push-up mechanism for pushing up the wafer 8 on the lower electrode 4, 2 is an exhaust system, and 5 is a gas controller.

During the plasma processing, the changeover switch 12
As a result, high-frequency power is applied to the lower electrode 4 from the lower-side high-frequency power source 7, the upper electrode 3 is grounded, and a high-frequency discharge is generated between the upper electrode 3 and the lower electrode 4. At this time, a self-bias is generated in the wafer 8 due to plasma generation, and the wafer 8 is electrostatically attracted to the lower electrode 4.

After the plasma processing, the changeover switch 1
2 applies high-frequency power to the upper electrode 3 from the upper-side high-frequency power supply 11 and grounds the lower electrode 4;
And a lower electrode 4 generates a high-frequency discharge. In this static elimination process, since high frequency power is applied to the upper electrode 3 and the lower electrode 4 is grounded, contrary to the plasma process, plasma ions collect on the wafer 8 side and are charged on the wafer 8 during the plasma process. The negative charge is neutralized, that is, the charge is eliminated.

After this discharge is continued for a while, the upper electrode 3
The application of the high-frequency power to the wafer 8 is stopped, and the wafer 8 is pushed up and carried out by the pushing up mechanism 9.

In the first embodiment, the high frequency power during the static elimination process is set to be smaller than the high frequency power during the plasma process. In addition, the type of gas and the frequency of electric power during the static elimination processing are the same as those during the plasma processing.

Embodiment 2 Next, Embodiment 2 of the present invention will be described in detail with reference to the drawings. Referring to FIG. 2, a second embodiment of the present invention provides a DC constant voltage power supply 13 to lower electrode 4 in order to enhance the adhesion between wafer 8 and lower electrode 4.
Is connected via a switch 14, and a bias voltage is supplied from the DC constant voltage power supply 13 to the lower electrode 4, thereby improving the adhesion between the wafer 8 and the lower electrode 4. The lower electrode 4 is connected to the switch 14 by switching from the DC constant voltage power supply 13 to the ground side.

The lower electrode 4 is provided with a changeover switch 12,
The lower high-frequency power source 7 is connected to the lower high-frequency power source 7 via the lower matching device 6.
To the ground side to be connected. Further, the upper electrode 3 is connected to the ground side by a changeover switch 12, and is switched from the ground side by the changeover switch 12 to the lower side high frequency power supply 7 via the upper side matching device 10.

The wafer 8 is arranged on the lower electrode 4, and a constant DC voltage is applied to the lower electrode 4 from a DC constant voltage power supply 13 by switching a switch 14. At this time, the wafer 8 is electrostatically attracted to the lower electrode 4. In this state, the changeover switch 12 switches the lower high-frequency power source 7 to the lower electrode 4.
By applying a high-frequency power to the first electrode and grounding the upper electrode 3, a high-frequency discharge is generated between the upper electrode 3 and the lower electrode 4, and the wafer 8 is subjected to plasma processing.

At the end of the plasma processing, the lower electrode 4 is switched from the DC constant voltage power supply 13 to the ground side by the switch 14 and grounded. Further, the lower electrode 4 is switched from the lower-side high-frequency power supply 7 to the grounding side by the changeover switch 12 and grounded. On the other hand, the upper electrode 3 is switched from the ground side by the changeover switch 12 to the lower high-frequency power source 7 via the upper matching device 10 and connected to the upper electrode 3. A high-frequency discharge is generated between the lower electrode 3 and the lower electrode 4.

After this discharge is continued for a while, the upper electrode 3
The application of the high-frequency power to the wafer 8 is stopped, and the wafer 8 is pushed up and carried out by the pushing up mechanism 9.

In the second embodiment, the DC constant voltage power supply 13
By supplying a bias voltage to the lower electrode 4 from
Since the adhesion between the wafer 8 and the lower electrode 4 is enhanced, the electrostatic force acting between the wafer 8 and the lower electrode 4 increases.

However, in the static elimination process according to the second embodiment, since high-frequency power is applied to the upper electrode 3 and the lower electrode 4 is grounded, contrary to the plasma process, plasma ions gather on the wafer 8 side and the plasma process is performed. At this time, the electrostatic force (minus charge) between the wafer 8 and the lower electrode 4 is neutralized, that is, static electricity is eliminated.

In the second embodiment, as in the first embodiment, the high-frequency power during the static elimination process is set smaller than the high-frequency power during the plasma process. In addition, the type of gas and the frequency of electric power during the static elimination processing are the same as those during the plasma processing.

[0029]

As described above, according to the present invention, high-frequency power is applied to the upper electrode in a manner opposite to that during the plasma processing.
Since the lower electrode was grounded and a high-frequency discharge was generated between the upper electrode and the lower electrode, sufficient positive ions were supplied to the lower electrode side to neutralize the electrostatic force that attracts the wafer to the lower electrode, When the wafer is pushed up by the push-up mechanism and carried out after the plasma processing, the wafer can be pushed up and carried out without causing the wafer to jump.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a second embodiment of the present invention.

FIG. 3 is a configuration diagram showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Chamber 2 Exhaust system 3 Upper electrode 4 Lower electrode 5 Gas controller 6 Lower matching device 7 Lower high frequency power supply 8 Wafer 9 Push-up mechanism 10 Upper matching device 12 Changeover switch 13 DC constant voltage power supply 14 Switch

Claims (3)

(57) [Claims] 1. A plasma processing apparatus, comprising: a changeover switch; and a high-frequency power supply, wherein high-frequency discharge is generated between an upper electrode and a lower electrode to perform plasma processing on a wafer on the lower electrode. Is operated when the wafer is peeled off from the lower electrode after the plasma processing. The changeover switch is for switching the lower electrode to the ground side to be grounded. The high-frequency power source is set to the upper electrode by the changeover switch. Wherein the plasma processing apparatus is switched and connected to supply high frequency power for static elimination to the upper electrode. 2. A plasma processing method comprising a plasma processing and a static elimination processing, wherein the plasma processing supplies a high-frequency power to a lower electrode, grounds an upper electrode, and forms a plasma on a wafer placed on the lower electrode. A plasma processing method, wherein the static elimination is performed by grounding the lower electrode and supplying high-frequency power to the upper electrode after the plasma processing of the wafer. 3. The high-frequency power supplied during the static elimination process is:
3. The plasma processing apparatus and the plasma processing method according to claim 1, wherein the power is set to be smaller than the high frequency power supplied during the plasma processing.