JPH0831918A - Plasma treatment apparatus and release method of holding force of electrostatic chuck - Google Patents

Abstract

PURPOSE:To release the attracting and holding force of an electrostatic chuck after a plasma treatment has been finished and to easily take out a work. CONSTITUTION:A first electrode 3 and a second electrode 4 which have been arranged to face each other are provided inside a vacuum container 2, and a plasma is generated when high-frequency electric power is applied to the electrodes 3, 4. An electrostatic chuck 5 which is composed of a dielectric is installed on the first electrode 3, and a wafer W is attracted and held when DC electric power is applied to the electrostatic chuck 5. After a plasma treatment to the wafer W has been finished by a grounding switch 19 which sets the potential of the electrostatic chuck 5 to a ground potential, the electrostatic chuck 5 and the wafer W are set to the ground potential.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing technique for performing a plasma process on a work in a state where the work is attracted by an electrostatic force, and a technique for releasing a holding force of an electrostatic chuck to the work after the plasma process.

[0002]

2. Description of the Related Art For example, in the processing of a semiconductor wafer in manufacturing a semiconductor device, C is used for forming a thin film of a desired substance on the surface of the semiconductor wafer as a work.
There are a VD process, an etching process for forming a fine circuit pattern on a work, and an ashing process for removing a resist film that is no longer needed after the resist process in the gas phase from the work. In order to perform these treatments, a plasma treatment apparatus is used.In the plasma treatment, by discharging under a reduced pressure of a reaction gas, reactive species such as electrons, ions and radicals which cannot be stably obtained under normal pressure are generated. This is a technique for generating the above-mentioned chemical vapor deposition and accelerating a predetermined chemical reaction to perform the above-mentioned CVD treatment and the like.

In a plasma processing apparatus for performing the above-mentioned plasma processing on a work, an electrostatic chuck is used to adsorb and hold the work. As a conventional electrostatic chuck, for example, Japanese Patent Laid-Open No. There is one such as that described in JP-A 1-227454.

In an electrostatic chuck which uses a semiconductor wafer as a work and attracts it by electrostatic force, an electrostatic force is generated between the electrostatic chuck and the work due to an electrostatic polarization phenomenon by applying DC power to the electrostatic chuck. The work is thereby attracted to the electrostatic chuck.

After the plasma processing is completed, it is necessary to release the suction holding force of the electrostatic chuck on the work in order to take out the work from the plasma processing apparatus. Just by cutting off the DC power to the electrostatic chuck to release the holding force, the potential of the electrostatic chuck and the work cannot be completely removed, and the electrostatic force remains between the work and the electrostatic chuck. The adsorption force will remain.

If the adsorption force remains, the work cannot be easily taken out from the plasma processing apparatus. Therefore, the potential of the electrostatic chuck and the work is completely removed, and the electrostatic force is completely removed. Need to be completely removed.

In the prior art, as disclosed in the above-mentioned publication, after applying a DC power having a potential opposite to the DC power applied for adsorption to the electrostatic chuck to remove the potentials of the electrostatic chuck and the work, I try to take out the work. On the other hand, a method may be adopted in which the work is mechanically forcibly taken out while the suction force remains.

[0008]

By the way, the present inventor has studied an electrostatic chuck used in a plasma processing apparatus. The following is the technique examined by the present inventor, and the outline thereof is as follows.

That is, in the method of applying the DC power of the reverse potential to remove the potentials of the electrostatic chuck and the work as in the prior art, the DC power at the time of adsorbing the work and the DC power of the reverse potential are applied. However, it has been found that if the DC power of the opposite potential is excessively applied, the electrostatic force between the work and the electrostatic chuck is generated again, and the attraction force is generated.

FIG. 5 shows changes with time in the potential of the work, that is, the wafer and the attraction force at this time.
As shown in the figure, the potential of the workpiece becomes smaller than the initial potential and approaches zero with the application of direct-current power of reverse potential, and the attraction force also decreases with the potential. When the electric potential of the work is zero, the suction force is also zero. However, if the DC electric power having the opposite electric potential is excessively applied, the electric potential passes through zero and has the electric potential opposite to the initial electric potential, and the adsorption force is generated again. Further, as described above, the method of mechanically forcibly peeling off the work has a problem that extra stress is applied to the work.

An object of the present invention is to provide a plasma processing technique in a plasma processing apparatus having an electrostatic chuck, which can release the suction holding force of the electrostatic chuck and easily take out a work after the processing is completed.

Another object of the present invention is to provide a technique for releasing the holding force of an electrostatic chuck, which removes the holding force of the electrostatic chuck on a workpiece.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0014]

Of the inventions disclosed in the present application, a representative one will be briefly described below.
It is as follows.

That is, the plasma processing apparatus of the present invention is
A first and a second arranged in the vacuum container so as to face each other.
It has electrodes and plasma is generated by applying high frequency power to these electrodes. The first electrode is provided with an electrostatic chuck made of a dielectric material, and a DC power is applied to the electrostatic chuck to attract and hold the work. The electrostatic chuck and the work are set to the ground potential after the plasma processing on the work is completed by the switching unit that sets the potential of the electrostatic chuck to the ground potential.

Further, the plasma processing apparatus of the present invention is the first
And a power control means for controlling the high frequency power generation means for applying the high frequency power between the second electrode and the high frequency power after the plasma processing so as to gradually reduce the high frequency power or to gradually reduce the high frequency power.

Further, in the electrostatic chuck holding force releasing method of the present invention, after the plasma treatment of the work, the DC circuit for applying DC power to the electrostatic chuck is set to the ground potential, and both electrodes are connected to each other. It is characterized in that a weak high-frequency power is applied to forcibly set the work to the ground potential to release the suction holding force.

In the electrostatic chuck holding force releasing method of the present invention, after the plasma treatment of the workpiece, the DC circuit for applying DC power to the electrostatic chuck is set to the ground potential, and the two electrodes are connected to each other. It is characterized in that the applied high-frequency power is gradually reduced to be extinguished, and the work is forcibly set to the ground potential to release the suction holding force of the electrostatic chuck.

[0019]

In the present invention having the above-mentioned structure, the potential of the electrostatic chuck is switched to the ground potential after the plasma processing on the work is completed, so that the attraction force by the electrostatic chuck can be surely removed. Therefore, the work can be easily taken out from the electrostatic chuck. Further, by switching the potential of the electrostatic chuck to the ground potential and gradually reducing or gradually reducing the high frequency power applied to both electrodes, the high frequency power for generating plasma is utilized. The electrostatic chuck can be forcibly set to zero potential, and the suction holding force of the electrostatic chuck can be released more quickly.

[0020]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a schematic sectional view showing a plasma processing apparatus according to an embodiment of the present invention. The plasma processing apparatus constitutes a plasma etching apparatus for forming a fine circuit pattern on the surface of a wafer. And has a vacuum container 2 in which a processing chamber 1 is formed. A lower electrode 3 as a first electrode is provided in the vacuum container 2, and an upper electrode 4 is arranged electrically opposite to and electrically insulated from the lower electrode 3, and the upper electrode 4 is a second electrode. Forming electrodes.

An electrostatic chuck 5 is formed by coating a film made of a dielectric on the upper surface of the lower electrode 3, and the electrostatic chuck 5 serves as a wafer W as a workpiece.
Are adsorbed and held.

The vacuum chamber 2 includes a processing chamber 1 and a gas supply device 6.
A gas supply path 7 is connected to the processing chamber 1 and a predetermined processing gas for etching processing is supplied from the gas supply device 6.
Supplied within. The gas supply passage 7 is provided with a mass flow controller 8 for controlling the flow rate of the processing gas.

The vacuum chamber 2 includes a processing chamber 1 and a vacuum pump 10.
A vacuum evacuation path 11 that connects to and is connected, and the inside of the processing chamber 1 is maintained at a predetermined degree of vacuum by the operation of the vacuum pump 10. The vacuum exhaust passage 11 is provided with an automatic pressure control device 12 for controlling the pressure inside the processing chamber 1.

A high-frequency oscillator 15 is connected to the upper electrode 4 and the lower electrode 3 as high-frequency power generation means for supplying high-frequency power, and the high-frequency oscillator 15 is controlled by a power control section (power control means) 16 for each electrode. The power applied to 3 and 4 is controlled to an arbitrary value.

A DC power supply 17 for generating an electrostatic force on the electrostatic chuck 5 is connected to the lower electrode 3 provided with the electrostatic chuck 5, and the electrostatic chuck 5 is connected via the lower electrode 3. Is electrically connected to the DC power supply 17. The lower electrode 3 has a structure grounded by a ground wire 18, and a ground switch 19 is provided on the ground wire 18, and the ground switch 19 constitutes a grounding means. Alternatively, an independent ground wire 18 may be directly connected to the electrostatic chuck 5.

The operation when the wafer W is used as a work by the plasma processing apparatus, the etching process is performed on the work, and the work is taken out after this process will be described below.

After mounting the wafer W on the electrostatic chuck 5, a desired etching processing gas is supplied from the gas supply device 6 through the mass flow controller 8 into the processing chamber 1 of the vacuum container 2 at a desired flow rate. At the same time, the processing chamber 1 is evacuated by the vacuum pump 10 and the processing chamber 1 is controlled to a desired pressure by the automatic pressure controller 12.

Under this condition, the high frequency oscillator 15 applies a relatively low output high frequency power of about 50 to 100 W to the upper electrode 4 and the lower electrode 3 to generate plasma 20. Almost at the same time, by applying DC power from the DC power supply 17 to the lower electrode 3, electrostatic force is generated on the electrostatic chuck 5 made of a dielectric film and the wafer W to generate the wafer W.
To the electrostatic chuck.

After that, 1000 required for the etching process
A relatively high output high frequency power of about 1500 W is applied to the upper electrode 4 and the lower electrode 3 to etch the wafer W. When the desired etching process is completed, the high frequency power and the direct current power are shut off to extinguish the plasma 20. In this state, the wafer W and the electrostatic chuck 5 have a potential, and the attraction force remains.

Therefore, in order to release the suction holding force of the wafer W by the electrostatic chuck 5, the ground switch 19 is operated to bring the electrostatic chuck 5 and the wafer W to the ground potential via the ground wire 18 and these potentials. To remove. FIG. 2 shows how the potential of the wafer W and the attraction force change with time at this time. As shown in FIG. 2, the potential of the wafer W becomes smaller with time as compared with when the ground switch 19 is turned on immediately after the plasma processing is finished, and approaches zero. At the same time, the suction power also decreases and approaches zero. After that, the potential of the wafer W becomes zero,
The adsorption force also becomes zero.

At this time, since the wafer W and the electrostatic chuck 5 are connected to the ground potential, the potential of the wafer W is held at the ground potential after a certain period of time, and the attraction force is also held at zero. Therefore, the phenomenon of having a reverse potential due to the application of excessive DC power, which has been a problem in the past, does not occur. In this way, the potentials of the electrostatic chuck 5 and the wafer W can be completely removed, so that there is no need to mechanically forcibly remove the wafer W.

The cause of the electric potential remaining on the wafer W and the electrostatic chuck 5 when the plasma 20 is extinguished by cutting off the application of the high frequency power to the upper electrode 4 and the lower electrode 3 is that the plasma 20 is generated. The inventor presumed that the reason is that a relatively high output high frequency power is applied. In other words, when high-output high-frequency power is applied, the average potential of the high-frequency power does not become zero potential, and it is speculated that it may have a DC component. On the other hand, it was thought that by applying a low output or a weak high frequency power to the electrodes, it is possible to generate a plasma having an average potential, that is, a DC component as close to zero potential as possible.

Therefore, the high frequency oscillator 15 and the DC power source 17
The energization control of the operation of No. 1 was performed as shown in the time chart of FIG. The DC power source 1 is applied to the lower electrode 3 at the time indicated by reference numeral 21.
DC power is applied from 7 and at the same time 5
A relatively low output high frequency power of about 0 to 100 W is applied to both electrodes 3 and 4. As a result, the wafer W is attracted to the electrostatic chuck 5, and then, as indicated by reference numeral 22, a relatively high output high frequency power required for etching is applied to both electrodes as described above.

When the desired etching process is completed at the time indicated by the reference numeral 23, the DC power is cut off and the ground switch 19 is turned on as described above. At the same time, as shown in FIG. 3, a weak high-frequency power of, for example, about 50 W is applied from the high-frequency oscillator 15 to both electrodes 3, 4. As described above, the weak high-frequency power of this level is considered to have an average potential as close to zero as possible and does not include a direct current component. Therefore, the reduced high-frequency power should be applied to both electrodes 3 and 4. As a result, the lower electrode 3 and thus the wafer W are forcibly set to the ground potential, in combination with the lower electrode 3 being grounded. This allows
The attraction and holding force of the electrostatic chuck 5 can be released more quickly than when the ground switch 19 is simply turned on.

In the case shown in FIG. 3, plasma 20 is used.
After finishing the etching process that generated, the application of high frequency power was made zero after a low output change in one step, but the high frequency power was reduced in multiple steps to terminate the application of high frequency power. May be.

FIG. 4 is a time chart showing another specific example of the method of releasing the suction holding force with respect to the electrostatic chuck 5.
In this case, when the desired etching process is completed,
In 3, the application of DC power is stopped and the ground switch 19 is turned on, and at the same time, a weak high-frequency power of about 50 W is applied to both electrodes 3 and 4 while gently weakening at a rate of reduction of about 10 W per second. As a result, the potentials of the wafer W and the electrostatic chuck 5 are forcibly set to the ground potential,
The electric potential disappears quickly and the adsorption force is removed.

In the illustrated embodiment, a predetermined high frequency power is applied from the time when the wafer W is attracted to the electrostatic chuck 5, but in FIG.
As shown by 4, the high frequency power may be gradually and gradually increased and applied. Even in the application method as shown in FIG. 3, the high frequency power may be gradually and gradually increased for application.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the embodiments and various modifications can be made without departing from the scope of the invention. Needless to say.

For example, the electrodes for generating the plasma are not limited to the parallel plate electrodes as shown in the figure. For example, a microwave generating means for sending a microwave into the processing chamber and a magnetic field are formed in the processing chamber. Plasma is formed by the magnetic field forming means,
Plasma may be formed by the interaction between the microwave and the magnetic field.

In the above description, the case where the invention made by the present inventor is mainly applied to the etching process, which is the field of use thereof, has been described, but the present invention is not limited to this, and for example, a CVD process, an ashing process, or the like can be used. Also in the case of performing it, it can be applied to any case as long as it is performed by plasma.

[0042]

Advantageous effects obtained by typical ones of the inventions disclosed in the present application will be briefly described.
It is as follows.

(1) The application of the DC power to the electrostatic chuck for adsorbing the work is stopped after the plasma treatment is completed, and the work and the electrostatic chuck are grounded to surely release the adsorbing force. Therefore, the work can be easily taken out from the electrostatic chuck after the plasma treatment.

(2). The high frequency power generation means for plasma generation is used to forcibly bring the potential of the electrostatic chuck to zero potential by applying low output high frequency power after the plasma processing is completed. Therefore, the attraction force of the electrostatic chuck can be released more quickly.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a plasma processing apparatus which is an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a state in which the electric potential and the attraction force of the electrostatic chuck and the work change with time when the electrostatic chuck is grounded after the plasma processing.

FIG. 3 is a time chart showing a method of applying high frequency power and DC power.

FIG. 4 is a time chart showing another method of applying high frequency power and DC power.

FIG. 5 is a characteristic diagram showing a state in which the potential and the attraction force of the electrostatic chuck and the work change with time when a reverse potential is applied to the electrostatic chuck after the plasma processing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Processing chamber 2 Vacuum container 3 Lower electrode (1st electrode) 4 Upper electrode (2nd electrode) 5 Electrostatic chuck 6 Gas supply device 7 Gas supply path 8 Mass flow controller 10 Vacuum pump 11 Vacuum exhaust path 12 Automatic pressure control device 15 High-frequency oscillator (high-frequency power generation means) 16 Power control unit (power control means) 17 DC power supply 18 Ground wire 19 Ground switch 20 Plasma W wafer (work)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuru Ogasawara 3-3, Fujibashi, Ome, Tokyo 2-3 Hitachi Hitachi Electronics Co., Ltd. (72) Inventor Hiroshi Marumoshi 3-3, Fujibashi, Ome, Tokyo 2 Hitachi-Higashi In Kyo Electronics Co., Ltd. (72) Inventor Masanari Harashima 3-3 Fujibashi, Ome City, Tokyo 2 Hitachi Tokyo Electronics Co., Ltd.

Claims (5)

[Claims] 1. A first electrode and a second electrode, which are arranged to face each other in a vacuum chamber in which a processing chamber is formed, and generate plasma by applied high-frequency power, and a dielectric provided on the first electrode. An electrostatic chuck that is composed of a body and holds a work by an electrostatic attraction force by the applied DC power; and a grounding unit that switches the potential of the electrostatic chuck to the ground potential after the plasma processing on the work is completed. A plasma processing apparatus characterized by the above. 2. A power control means for controlling a high-frequency power generation means for applying a high-frequency power between the first and second electrodes to gently reduce the high-frequency power after the plasma processing. The plasma processing apparatus described. 3. A power control means for controlling the high frequency power generating means for applying the high frequency power between the first and second electrodes to gradually reduce the high frequency power after the plasma processing. 1. The plasma processing apparatus according to 1. 4. A plasma treatment is performed on the work by a plasma generated between a first electrode provided in the processing chamber of the vacuum container and provided with an electrostatic chuck for adsorbing the work and a second electrode facing the first electrode. After that, a DC circuit for applying DC power to the electrostatic chuck is connected to the ground potential, and a weak high-frequency power is applied between the first and second electrodes to force the work to the ground potential. The electrostatic chuck holding force releasing method is characterized in that the electrostatic chuck holding force for the workpiece is released. 5. A plasma treatment is performed on the work by a plasma generated between a first electrode provided in the processing chamber of the vacuum container and provided with an electrostatic chuck for attracting the work and a second electrode facing the first electrode. After that, a DC circuit for applying DC power to the electrostatic chuck is connected to the ground potential, and the high frequency power applied between the first and second electrodes is gradually reduced to disappear, and the work is A method for releasing the holding force of an electrostatic chuck, which is forcibly set to a ground potential to release the attraction holding force of the electrostatic chuck with respect to the workpiece.