JPH08321494A - Plasma treatment equipment - Google Patents

Abstract

PURPOSE: To prevent transfer of a shadow formed by a meshy metal by a method wherein a part of a second electrode is provided in a part surrounded by an insulator, while the meshy metal is provided on a sample, and an alternating current is superimposed on a coil. CONSTITUTION: A strong ECR plasma is generated in a part being closer to a microwave introducing part 2 than a sample 9 by an introduced microwave, a coil 8 and gas. A high-frequency wave is impressed between a first electrode 10 and a second electrode 11 by a high-frequency power source 12 and a matching unit 14 attached. Moreover, ions are moved in a lateral direction by superimposing an alternating current on the coil 8, so as to avoids transferring a shadow formed by a meshy metal provided in a part on the sample 9 onto the sample 9. According to this constitution, an AC voltage is impressed stably, effectively and without fluctuation and anisotropic plasma treatment is executed stably.

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 more particularly to a plasma apparatus which uses microwaves and AC bias in combination for forming and etching various films during manufacturing of semiconductor elements and the like. is there.

[0002]

2. Description of the Related Art The miniaturization of semiconductor devices is being advanced with the miniaturization and high integration of semiconductor devices. Compared with conventional film formation and etching techniques, the thin film processing method using microwave plasma is already well-established as a method suitable for microfabrication, but when an AC bias is applied to the sample, film quality is improved and film formation and etching are performed. Attention has been paid to the fact that the processing shape can be improved.

FIG. 11 schematically shows a conventional example in which microwave and high frequency bias are used in combination and a magnetic field is used to generate ECR plasma, for example, as described in Japanese Patent Application Laid-Open No. 2-127029. 1 is a microwave generator, 2 is microwave introduction means, 3 is a quartz bell jar, 4 is a metal container, 5 is gas introduction means, 6 is a valve, 7 is exhaust means, 8
Is a coil, 9 is a sample, 10 is a first electrode for supporting the sample, 11 is a second electrode installed for applying an electric potential to plasma, and 12 is an AC generator.

An airtight container is constituted by the quartz bell jar 3 and the metal container 4, and the gas is supplied while the predetermined gas is set to a predetermined pressure by the gas introduction means 5, the valve 6 and the exhaust means 7. The microwave generated from the microwave generator 1 is input into the airtight container via the microwave introducing means 2 such as a waveguide or a coaxial line and the quartz bell jar 3. Electron Cyclotron Resonance (ECR), which is the interaction between the magnetic field of the coil 8 and the microwave.
Due to the phenomenon, the gas in the airtight container is efficiently turned into plasma. The plasmatized ions are attracted by the alternating current applied between the first electrode 10 and the second electrode 11 and applied to the sample surface with good directionality.

[0005]

In the conventional device as described above, the second electrode is installed farther from the microwave incident part than the quartz bell jar which is an insulator. Usually, in order to avoid metal contamination, the coil strength is adjusted so that the microwave is mainly absorbed and the plasma strength is increased in the interior surrounded by the quartz bell jar, and radicals, ions, etc. are efficiently added to the sample. Is configured to be incident. In this case, there is only weak plasma diffused around the second electrode. For this reason,
The potential difference between the strong plasma and the second electrode increases, and the potential difference between the plasma and the first electrode or sample decreases. Further, the voltage difference between the strong plasma and the second electrode has a drawback that it varies depending on the processing conditions and the diffusion state of the plasma, and therefore the potential difference between the strong plasma and the first electrode or the sample also has a drawback. .

[0006]

In order to achieve the above object, the present invention relates to an airtight container for storing a low-pressure gas or a gaseous mixture therein, a means for introducing the gas into the airtight container, and A first electrode that is insulated from the airtight container and is installed inside the airtight container and that supports a sample; and a microwave that is connected to the airtight container and that generates microwaves to generate plasma in the airtight container. A generator, a coil for generating a magnetic field, a second electrode installed in the airtight container for applying an electric potential to the plasma, the frequency is lower than the frequency of the microwave, and its amplitude is adjustable,
And an AC generator applied between the first electrode and the second electrode, and an insulator in a part of the airtight container or a part of the inside of the airtight container, and the insulator is provided inside the insulator. In a plasma processing apparatus configured to generate plasma, at least a part of the second electrode is provided in a portion surrounded by the insulator, a mesh metal is provided on a sample, and an alternating current is applied to the coil. The plasma processing apparatus is characterized by preventing shadow transfer due to mesh metal by superimposing an electric current.

By covering the surface of the second electrode with an insulator, the influence of metal contamination can be reduced. In this case, the thickness of the insulator covering the surface of the second electrode is
By making it thinner than the thickness of an insulating material such as a quartz bell jar installed around the electrode, it is possible to retain the function of applying an electric potential to the plasma.

By providing at least a part of the second electrode at a portion surrounded by an insulator such as quartz bell jar, that is, a portion where strong plasma is generated or a portion closer to the strong plasma, a strong plasma can be obtained. The potential difference between the second electrodes can be reduced, and an AC voltage can be applied between the strong plasma and the first electrode or the sample effectively and without fluctuation.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described below with reference to FIG. The microwave power of 2.45 GHz generated by the microwave generator 1 is introduced into the airtight container 15 via the microwave introduction means 2 such as a waveguide or a coaxial line and the quartz bell jar 3. The airtight container is composed of a quartz bell jar 3 and a metal container 4, to which a gas introducing means 5, a valve 6 and an exhausting means 7 are connected. In an airtight container 15
A sample 9, a first electrode 10 that supports the sample and is insulated from the metal container 4, and a second electrode 11 are installed. Due to the introduction of microwaves, the coil 8 and the gas, the sample 9 has a stronger E near the microwave introduction part.
CR plasma is generated. A high frequency of several + KHz to several + MHz is applied between the first electrode 10 and the second electrode 11 via the high-frequency power source 12 and the matching device 14. Since the second electrode 11 is installed in a portion where the plasma is strong in the portion surrounded by the quartz bell jar 3, the potential difference between the strong plasma and the second electrode 11 is reduced, and the second electrode 11 can be efficiently and varied. Without, high frequency can be applied between the plasma and the sample. By applying this high frequency, it is possible to align the directionality of ions and perform anisotropic and high-rate etching.

2 and 3 show a second embodiment of the present invention, which shows an example of the structure of the second electrode. This is an example of using a metal ring such as aluminum. The surface area of the electrode 11 is preferably larger than that of the sample 9. As the second electrode 11, as shown in the cross-sectional view of FIG. 3, a metal 11-1 such as aluminum is covered with an insulator 11-2 (for example, alumina) having a thickness of several + to several hundreds of micrometers. If the metal is used, the metal contamination can be reduced and the metal consumption by plasma can be reduced.

The microwave introducing means 2 shown in FIG.
It includes means for monitoring incident and reflected waves by an isolator and a directional coupler.

FIG. 4 shows a third embodiment of the present invention, in which the gas discharged from the gas introducing means 5 is made to have a uniform pressure in the gas buffer portion 13, and then the fine holes formed in the metal container 4 are formed. It passes through and is introduced into the airtight container 15 through the space formed by the second electrode 11 and the inner surface of the quartz bell jar 3. That is, a part of the second electrode 11 forms a part of the gas introduction path,
The gas is introduced from the upper part of the second electrode 11. By doing so, the gas can be supplied near the strong plasma.

FIG. 5 shows a fourth embodiment of the present invention, showing an example in which the inside of the second electrode is used as a gas introducing passage. The same effect as in FIG. 4 is obtained. 4 and 5, both the second internal electrode 11 and the metal container 4 are in contact with each other. As described with reference to FIG. 3, the second electrode 11 is connected to the insulator 1
When covered with 1-2, the metal container 4 and the second electrode 11
It is necessary to remove a part of the insulating material so that a metal-metal joint is formed.

FIG. 6 shows a fifth embodiment of the present invention. In order to further reduce the potential difference between the strong plasma and the second internal electrode 11, as shown in the schematic view of FIG. In this case, the portion of the magnetic field strength that causes electron cyclotron resonance (ECR
It is preferable that the second electrode 11 is installed on the side close to the sample 9 and the mesh pitch is set to a large value of 10 mm or more so as not to interfere with ions and particles while avoiding the vicinity of (point).

The shape of the mesh is not limited to the rectangular shape shown in FIG. 7, and for example, a mesh having metal in the circumferential direction and the radial direction can be used. Although FIGS. 6 and 7 describe the case where the mesh is installed at a position closer to the sample 9 than the ECR point, if a metal or a metal coated with an insulator is installed along the electromagnetic field of the microwave, the microwave electromagnetic ECR without disturbing the world
The second electrode 1 is also provided in the part farther from the sample 9 with respect to the point.
A part of 1 can be installed. When a metal is placed on the sample 9, the shadow of the metal may be transferred onto the sample. In this case, it can be avoided by superimposing an alternating current on the coil 8 to move the ions laterally. The description of FIGS. 6 and 7 and the matters described below are not limited to the device in which the periphery of the portion where the strong discharge is generated is surrounded by the insulator, and the periphery of the portion where the strong discharge is generated is surrounded by the metal. Similarly, for the device, there is an advantage that AC power can be efficiently applied to plasma.

FIG. 8 shows a sixth embodiment of the present invention. The airtight container is a metal container 4, an insulator 3-1 installed on a part of the surface of the metal container, and a quartz plate 3-2 for introducing microwaves.
It consists of. By inserting the second electrode 11 to a position inside the airtight container surrounded by the insulator 3-1, the same effect as that shown in FIG. 1 can be obtained.

FIG. 9 shows a seventh embodiment of the present invention. A dielectric 16 made of an insulator or a semiconductor is installed between the first electrode 10 and the sample 9, and the sample 9 is electrostatically attracted to the dielectric 16. A configuration in the vicinity of the first electrode 10 when a so-called electrostatic chuck state is provided will be shown.
The dielectric 16 preferably has a high dielectric constant. The first electrode 10 and the dielectric 16 are insulated from the metal container 4 or a portion having the same potential as the metal container 4 by the insulator 17. As shown in FIG. 10, the surface of the dielectric 11 is provided with irregularities so that the gas source 1
A gas such as helium is introduced from 8 and the dielectric 16 and the sample 9
Improves heat transfer between and. The first electrode 10 or the insulator 17 is provided with a tube through which a heating or cooling fluid is passed to control the temperature of the sample 9. AC generator 1
The alternating current generated in 2 is applied to the first electrode 10 via the matching unit 14 and the capacitor 14-1 in the matching unit 14, and the electrostatic chuck high-voltage power supply 19 also acts on the inductance installed in the matching unit 14. Circuit element consisting of resistor 14-
It is likewise applied to the first electrode 10 via 2. The second electrode 11 includes a metal 11-1 and an insulator 11-2 covering the metal 11-1.
The metal 11-1 is in contact with the metal container 4.
A potential difference with respect to an alternating current is generated at the site of the dielectric 16 or the insulator 11-2, but the relative permittivity ξγ of the constituent material of the dielectric 16 or the insulator 11-2 and its thickness d (mm) are / Ξγ <<
By filling 1 mm, the frequency of AC is 10
Above about 0 kHz, the potential difference can be small.

Although the embodiment has been described so far for the etching apparatus, the invention can be similarly applied to a film forming apparatus such as a sputtering apparatus or a CVD apparatus.

[0019]

According to the present invention, the potential difference between the strong plasma and the second electrode can be reduced, and the alternating voltage can be applied stably and effectively between the strong plasma and the first electrode or the sample without fluctuation. Therefore, there is an effect that the anisotropic plasma treatment can be stably performed. Further, although the mesh-shaped metal is provided on the sample, the effect of preventing the transfer of the shadow by the mesh-shaped metal can be obtained by superimposing an alternating current on the coil.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional configuration diagram of a processing chamber portion of a plasma processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a perspective external view of a second electrode of the plasma processing apparatus of the second embodiment of the present invention.

3 is a vertical cross-sectional view of the second electrode of FIG.

FIG. 4 is a vertical cross-sectional configuration diagram of a processing chamber portion of a plasma processing apparatus according to a third embodiment of the present invention.

FIG. 5 is a vertical cross-sectional view of a processing chamber portion of a plasma processing apparatus according to a fourth embodiment of the present invention.

FIG. 6 is a vertical cross-sectional configuration diagram of a processing chamber portion of a plasma processing apparatus according to a fifth embodiment of the present invention.

FIG. 7 is a perspective external view of the second electrode of FIG.

FIG. 8 is a vertical cross-sectional configuration diagram of a processing chamber portion of a plasma processing apparatus according to a sixth embodiment of the present invention.

FIG. 9 is a vertical cross sectional view of a processing chamber portion of a plasma processing apparatus according to a seventh embodiment of the present invention.

FIG. 10 is a plan view of the dielectric of FIG.

FIG. 11 is a vertical cross-sectional configuration diagram of a processing chamber portion of a conventional example of a plasma processing apparatus.

[Explanation of symbols]

1 ... Microwave generator, 2 ... Microwave introducing means, 3 ...
Quartz bell jar, 3-1 ... Insulator, 3-2 ... Quartz plate, 4 ...
Metal container, 5 ... Gas introducing means, 6 ... Valve, 7 ... Exhausting means, 8 ... Coil, 9 ... Sample, 10 ... First electrode, 11 ...
2nd electrode, 12 ... AC generator, 13 ... Gas buffer, 14 ... Matching device.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C30B 25/02 C30B 25/02 P H01L 21/203 H01L 21/203 S 21/205 21/205 21 / 28 21/28 F 21/285 21/285 C 21/31 21/31 C H05H 1/46 9216-2G H05H 1/46 C (72) Inventor Motohiko Yoshikai 794 Higashitoyo, Higashitoyo, Yamaguchi Prefecture Hitachi Te Kuno Engineering Co., Ltd., Kasado Plant (72) Inventor Yoshinao Kawasaki, 794, Higashi-Toyoi, Kudamatsu City, Yamaguchi Prefecture Stock company Hitachi Ltd., Kasado Plant, (72) Shoji Saikai, 794, Higashi-Toyoi, Shimomatsu, Yamaguchi Prefecture Stock company Hitachi Ltd. Kasado factory

Claims (1)

[Claims] 1. An airtight container for storing a low-pressure gas or a gaseous mixture therein, a means for introducing the gas into the airtight container, and an inside of the airtight container insulated from the airtight container and supporting a sample. A first electrode, a microwave generator that is connected to the airtight container and that generates a microwave for generating plasma in the airtight container, a coil that generates a magnetic field, and a potential for applying the plasma to the plasma. A second electrode installed in the airtight container, an alternating current generator whose frequency is lower than the frequency of the microwave and whose amplitude can be adjusted, and which is applied between the first electrode and the second electrode,
In a plasma processing apparatus having an insulator in a part of the airtight container or a part of the inside of the airtight container and configured so that the plasma is generated inside the insulator, the periphery is surrounded by the insulator. Providing at least a part of the second electrode in the surrounded portion, providing a mesh-shaped metal on the sample,
A plasma processing apparatus, characterized in that transfer of a shadow due to a mesh-shaped metal is prevented by superimposing an alternating current on the coil.