JPH1041280A - Plasma treating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma treating apparatus which never sputters the inner wall of a plasma generator with ions. SOLUTION: A plasma treating apparatus 100, esp. down flow asher, has at least a pair of magnets 144a, 144b to generate a magnetic field generally perpendicular to the direction of an electric field generated between at least a pair of electrodes disposed on the outer wall edges of a plasma generator 127. This causes electrons generated with a plasma in the plasma generator to drift and flows in the direction generally perpendicular to the electric filed between the electrodes and magnetic field between the magnets and hence ions flowing in almost the same direction as the electrons never collide against the inner wall of the plasma generator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a plasma processing apparatus, and more particularly to a downflow ashing apparatus.

[0002]

2. Description of the Related Art Conventionally, in a plasma processing apparatus, for example, an ashing apparatus 10, a mounting table on which an object to be processed can be mounted is provided in an airtight processing chamber, and a vacuum exhaust system is connected to the processing chamber. It is configured such that a predetermined reduced-pressure atmosphere is maintained. And in the upper part of the processing chamber,
As shown in FIG. 6, a plasma generation chamber 12 made of a dielectric material, for example, quartz or ceramic communicates. The plasma generation chamber 12 is composed of a substantially inverted-cup-shaped plasma diffusion section 14 and a substantially tubular plasma generation section 16 connected to the top thereof, and constitutes a so-called bell jar type plasma generation chamber 12. .

[0003] Electrodes, for example, a pair of a first electrode 18a and a second electrode 18b are provided on the outer peripheral edge of the plasma generating section 16 in a substantially parallel direction. Also, the plasma generator 1
A gas supply means is connected to the upper end of 6, so that a predetermined processing gas is supplied into the plasma generator 16.

At the time of plasma processing, the plasma generator 16
A predetermined processing gas is supplied to the first electrode 18.
When a predetermined high-frequency power is applied from the high-frequency power supply 22 to the a and the second electrode 18b via the matching unit 20, the processing gas is turned into plasma. Then, the plasma generated in the plasma generating section 16 is efficiently and uniformly diffused in the plasma diffusing section 14 and guided into the processing chamber in which a predetermined reduced-pressure atmosphere is maintained. The processing is performed.

[0005]

However, in the conventional plasma apparatus, during the ashing process, the inner wall of the plasma generator 16 at the position where the first electrode 18a and the second electrode 18b are provided is generated together with the plasma. Sputtering may occur due to ion collisions, for example, and pinholes may be generated in that portion, and it is necessary to replace the plasma generator 16 in a short time.

Further, the inner wall of the plasma generating section 16 is sputtered to generate irregularities, and the plasma is disturbed, and the plasma density is reduced or non-uniform. The constituent materials adhere to the object to be processed, which is a factor that lowers the production yield.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of a conventional plasma processing apparatus, and has as its object to sputter an inner wall of a plasma generating section by ions generated together with plasma. An object of the present invention is to provide a new and improved plasma processing apparatus capable of preventing the occurrence of plasma and further improving the plasma density.

[0008]

According to a first aspect of the present invention, there is provided a plasma processing apparatus comprising: a mounting table for mounting an object to be processed in a processing chamber; A plasma generating chamber, at least a plasma generating section of the plasma generating chamber is formed of a substantially tubular dielectric, and a predetermined high-frequency power is applied to an electrode provided so as to surround the plasma generating section. In the plasma processing apparatus for performing a predetermined plasma process on the object to be processed on the mounting table by converting the introduced predetermined processing gas into a plasma and introducing the plasma into the processing chamber, A magnet is arranged so as to surround the plasma generating part so that the direction of the magnetic field is formed substantially perpendicular to the direction of the electric field generated when high-frequency power is applied. It is characterized in that was.

Since the plasma processing apparatus according to the present invention is configured as described above, the electrons generated together with the plasma in the plasma generating section cause an E × B drift, and the direction of the electric field generated between the electrodes and the magnet It flows almost perpendicularly to the direction of the magnetic field generated between them. Similarly, ions generated together with the plasma are accelerated by the collision of electrons, so that the ions also flow in substantially the same direction as the electrons.
Therefore, since the inner wall of the plasma generating section is not sputtered by the ions, the plasma generating section does not need to be replaced. Further, since no irregularities are generated, a uniform plasma can be supplied into the processing chamber, and the production yield can be reduced. Can be improved. Further, since the flow of ions can be adjusted, the plasma density can be increased.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
An embodiment in which the plasma processing apparatus according to the present invention is applied to a downflow ashing apparatus will be described in detail. In the following description, components having substantially the same functions and configurations will be denoted by the same reference numerals, and redundant description will be omitted.

In the ashing apparatus 100 shown in FIG. 1, a processing chamber 104 is formed in an airtight, substantially cylindrical processing container 102 made of a conductive material, for example, aluminum whose surface is subjected to oxidized alumite processing. . An object to be processed, for example, a semiconductor wafer (hereinafter, referred to as a semiconductor wafer) is provided in the processing chamber 104.
It is called "wafer". A) A substantially cylindrical stage 106 on which W can be placed is provided via an insulating support 108 made of an insulating material, for example, alumina ceramic.

A heater 112 connected to an AC power supply 110 is provided inside the stage 106. Therefore, when a predetermined AC power is supplied from the AC power supply 110 to the heater 112 via the power adjusting means (not shown), the stage 1
06 is heated, and the wafer W mounted on the stage 106 is also heated.
The temperature is controlled by a heater 1 (not shown).
The AC power supplied to the power supply 12 is adjusted so that a predetermined temperature is maintained.

A lifter 1 serving as a means for raising and lowering the wafer W
Reference numeral 14 denotes a structure in which, for example, three substantially rod-shaped shafts penetrate from the back surface to the front surface of the stage 106 at an intermediate portion between a substantially central portion of the stage 106 and a peripheral portion of the wafer W. Further, the lifter 114 is connected below the stage 106 such that the above-mentioned substantially rod-shaped shaft becomes, for example, one substantially rod-shaped shaft, and the substantially rod-shaped shaft is connected to a motor M116 which is a driving means of the lifter 114. Have been.

Therefore, when performing the plasma processing, when the wafer W is carried into a predetermined position above the stage 106 via the gate valve 118 by the transfer means (not shown), the motor M116 is driven and the lifter 114 is driven. , And the wafer W is placed on the stage. Further, after the plasma processing, the motor M116 is driven to raise the lifter 114, and the wafer W mounted on the stage 106 is carried out by the carrying means (not shown) through the gate valve 118. Have been.

An exhaust pipe 120 is provided at the lower part of the processing vessel 102.
The exhaust pipe 120 is further provided with a valve 12.
2, a vacuuming means P124, for example, a turbo molecular pump is connected. Therefore, the evacuation means P124
By the operation of, the processing chamber 104 is evacuated through the valve 122 and the exhaust pipe 120 so that the inside of the processing chamber 104 has a predetermined reduced-pressure atmosphere.

Above the processing chamber 104, a plasma generating chamber 126 made of a dielectric material, for example, quartz or ceramic is provided. This plasma generation chamber 12
Numeral 6 is a so-called bell jar type chamber composed of a substantially tubular plasma generating portion 127 and a plasma diffusion portion 128 having a substantially tubular upper portion and a substantially inverted bowl shape from a substantially central portion to a lower portion. I have. Plasma generator 127
The upper part of the plasma diffusion part 128 is substantially the same type, and is connected by a pipe joint (not shown) so that the insides thereof penetrate. Therefore, since the plasma generating section 127 and the plasma diffusing section 128 can be separated from each other, they can be separately maintained when a reaction product adheres to them or when they are etched by plasma. I have.

Next, the connection between the plasma diffusion section 128 forming the lower part of the plasma generation chamber 126 and the processing chamber 104 will be described. The upper wall portion of the processing chamber 104 has substantially the same shape as the lower opening surface of the plasma diffusion portion 128 having a substantially inverted bowl shape, and is provided with an opening having substantially the same shape as the wafer W. Therefore, the inside of the processing chamber 104 and the plasma diffusion unit 128
A plasma generation chamber 126 is connected to the upper surface of the stage 106 by a pipe joint (not shown) in a direction substantially perpendicular to the upper surface of the stage 106 so as to penetrate into the plasma generation unit 127. With the above configuration, the plasma generated in the plasma generation unit 127 can be efficiently introduced into the processing chamber 104 and uniformly diffused.

Further, a gas supply pipe 130 is connected to the upper portion of the plasma generating section 127 by a pipe joint (not shown), and at least a portion directly connected to the plasma generating section 127 has substantially the same shape as the plasma generating section 127. , The processing gas can be uniformly introduced into the plasma generating section 127. And again, the gas supply pipe 13
The gas supply source 136 is set to 0 via a valve 132 and a mass flow controller MFC 134 for adjusting the gas flow rate.
Is connected. Therefore, a predetermined processing gas, for example, an O ₂ gas is uniformly supplied from the gas supply source 136 into the plasma generation unit 127 via the mass flow controller MFC 134, the valve 132, and the gas supply pipe 130.

At the outer peripheral edge of the plasma generating section 127,
As shown in FIGS. 1 to 3, the first electrode 138a and the second electrode 138b are provided in substantially parallel directions, respectively.
It is preferable that the surface facing the plasma generator 127 has at least substantially the same shape as the inner wall surface of the plasma generator 127. A high-frequency power source 142 is connected to the first electrode 138a via a matching unit 140, and the second electrode 138b is grounded. Therefore, when a predetermined high-frequency power, for example, 13.56 MHz high-frequency power is applied from the high-frequency power supply 142 to the first electrode 138a via the matching unit 140, an electric field is generated in the plasma generation unit 127 between the first electrode 138a and the second electrode 138b. Is generated, and plasma is generated from the processing gas supplied from the gas supply source 136.

Further, as shown in FIGS. 1 to 3, the first permanent magnet 144a and the second permanent magnet 144b according to the present embodiment are provided on the outer peripheral portion of the plasma generating portion 127.
It is provided in a direction substantially perpendicular to the direction of the electric field generated between the first electrode 138a and the second electrode 138b. That is, the first permanent magnet 144a and the second permanent magnet 144b
Are in substantially parallel directions, and the first electrode 138a and the second
It is provided in a direction substantially perpendicular to the electrode 138b. It is preferable that the surfaces of the first permanent magnet 144a and the second permanent magnet 144b facing the plasma generator 127 have at least substantially the same shape as the inner wall surface of the plasma generator 127.

Here, the flow of electrons in the plasma generator 127 during the plasma processing will be described with reference to FIG. As described above, the first electrode 138a and the second electrode 1
When a predetermined high-frequency electric power is applied to the plasma generating unit 127, an electric field is generated, and plasma, ions, and electrons are generated in the plasma generating unit 127 from the processing gas supplied from the gas supply source 136. Among them, electrons flow in the direction of the electric field when the first permanent magnet 144a and the second permanent magnet 144b according to the present embodiment are not provided. One of the ions is accelerated by the collision of the electrons and flows in substantially the same direction as the electrons, so that the inner wall of the plasma generating unit 126 is sputtered by the ions.

Ashing device 10 according to the present embodiment
0, the first permanent magnet 144a and the second permanent magnet 144b provided in a direction substantially perpendicular to the electric field direction.
The electrons cause an E × B drift and flow in a direction substantially perpendicular to the electric field direction and the magnetic field direction. Therefore, the ions also flow in substantially the same direction as the electrons, and the inner wall of the plasma generation unit 127 is not sputtered by the ions. Therefore, not only does the plasma generation unit 127 need to be replaced, but also the unevenness does not occur. It is possible to supply a suitable plasma into the processing chamber 104. Further, since the flow of ions can be adjusted, the plasma density can be increased.

The ashing device 200 shown in FIG.
As shown in FIG.
Instead of the permanent magnet 144a and the second permanent magnet 144b,
A configuration in which the electromagnet 202 is provided may be employed. In this case, by adjusting the DC power applied from the DC power supply 204 to the coil 206, the magnetic field generated in the plasma generating unit 127 can be adjusted, and the above-described flow of electrons can be maintained in a desired state. It is possible.

Further, the ashing device 30 shown in FIG.
0, a configuration in which the permanent magnet 302 is provided at a position away from the plasma generation unit 127 and only the magnetic field generated from the permanent magnet 302 is propagated into the plasma generation unit 127 by the magnetic field transmission unit 304 made of, for example, iron. It may be.

Although the preferred embodiment of the present invention has been described with reference to the accompanying drawings, the present invention is not limited to this configuration. Within the scope of the technical idea described in the claims, those skilled in the art can come up with various modified examples and modified examples, and these modified examples and modified examples are also within the technical scope of the present invention. It is understood that it belongs to.

In the above embodiment, an example has been described in which a pair of magnets are provided on the outer peripheral portion of the plasma generating portion to generate a magnetic field in the plasma generating portion. However, the present invention is not limited to such a configuration. As long as the direction of the magnetic field is formed in a direction substantially perpendicular to the direction of the electric field generated between the electrodes, a magnet may be provided at any place, and a configuration in which a magnetic field is generated by a plurality of magnets may be employed.

In the above-described embodiment, the configuration in which the magnet is provided on the outer peripheral edge of the plasma generating section has been described as an example. However, the present invention is not limited to such a configuration, and the magnet is provided inside or on the inner wall of the plasma generating section. It is good also as a structure provided.

In the above embodiment, the configuration in which a magnetic field is generated in the plasma generating section by one electromagnet has been described as an example. However, the present invention is not limited to such a configuration.
A configuration in which a magnetic field is generated by a plurality of electromagnets may be employed.

In the above embodiment, an ashing apparatus having a substantially inverted bowl-shaped plasma diffusion section has been described as an example. However, the present invention is not limited to such a configuration, and may be, for example, a substantially flask-shaped or substantially tubular-shaped one. It is also applicable to a configuration having the plasma diffusion portion.

In the above embodiment, an example in which a semiconductor wafer is used as an object to be processed has been described. However, the present invention is not limited to this configuration, and can be applied to an LCD substrate. .

[0031]

As described above, since the plasma processing apparatus according to the present invention is configured as described above,
The electrons generated together with the plasma in the plasma generation section
An E × B drift is caused to flow in a direction substantially perpendicular to the direction of the electric field generated between the electrodes and the direction of the magnetic field generated between the magnets. Therefore, the ions generated with the plasma are
The electrons flow in almost the same direction as the electrons, and they collide with the inner wall of the plasma generating section and no longer sputter. This not only eliminates the need to replace the plasma generating section, but also eliminates unevenness, so that uniform plasma is introduced into the processing chamber. It becomes possible to supply, and the production yield can be improved. And
Since the flow of ions can be adjusted, the plasma density can be increased.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an embodiment of a plasma processing apparatus to which the present invention can be applied.

FIG. 2 is a perspective view schematically showing a plasma generation container of the plasma processing apparatus of FIG.

FIG. 3 is a schematic sectional view showing a magnetic field direction and an electric field direction in a plasma generation chamber of the plasma processing apparatus of FIG.

FIG. 4 is a schematic sectional view showing a magnetic field direction and an electric field direction in a plasma generation chamber of the plasma processing apparatus according to the present embodiment.

FIG. 5 is a schematic sectional view showing a magnetic field direction and an electric field direction in a plasma generation chamber of the plasma processing apparatus according to the present embodiment.

FIG. 6 is a perspective view schematically showing a plasma generation container of a conventional plasma processing apparatus.

[Explanation of symbols]

 Reference Signs List 102 processing container 104 processing chamber 106 stage 112 heater 114 lifter 118 gate valve 120 exhaust pipe 124 evacuation means 126 plasma generation chamber 127 plasma generation unit 128 plasma diffusion unit 130 gas supply pipe 134 mass flow controller 136 gas supply source 138a first electrode 138b Second electrode 140 Matching device 142 High-frequency power source 144a First permanent magnet 144b Second permanent magnet 202 Electromagnet 304 Magnetic field propagation means

Claims (1)

[Claims] An apparatus has a mounting table for mounting an object to be processed in a processing chamber, a plasma generating chamber for generating plasma above the processing chamber, and at least a plasma generating part of the plasma generating chamber has a substantially tubular dielectric. A predetermined high-frequency power is applied to an electrode, which is configured to surround the plasma generation unit, and converts a predetermined processing gas introduced into the plasma generation chamber into a plasma, and the plasma is supplied into the processing chamber. By introducing, in the plasma processing apparatus for performing a predetermined plasma processing on the object to be processed on the mounting table, substantially perpendicular to a direction of an electric field generated when a predetermined high-frequency power is applied to the electrode A plasma processing apparatus, wherein a magnet is arranged so as to surround the plasma generating portion so that a direction of a magnetic field is formed in the direction.