JPH07122495A - Plasma generating equipment - Google Patents

Abstract

PURPOSE:To provide a plasma generating equipment capable of forming an uniform thin film on a substrate large in area, at a high speed. CONSTITUTION:The outer periphery of coaxial waveguides 10a, 10b is connected with a conductor plate 11. The inner axes of the coaxial waveguides 10a, 10b are connected with both ends of a copper wire 14 through a dielectric plate 13. A total reflection terminal or the like is connected with the coaxial waveguide 10a, and a microwave power source is connected with the coaxial waveguide 10b. A strip line type electrode is formed by bendin the copper wire 14 in a zigzag type on the dielectric plate 13. Gas pipes 12a, 12b are arranged on both sides of the strip line type electrode so as to face each other. A plurality of gas discharge holes are bored so as to face the strip line type electrode. Permanent magnets 15a, 15b are arranged on both end portions of the strip line type electrode, and a magnetic field in the Z axis direction is generated. A substrate 16 is arranged above the strip line type electrode, and moved in the direction of an arrow mark A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to plasma CVD for forming large area thin films used in various electronic devices such as amorphous silicon solar cells, thin film semiconductors and photosensors.
The present invention relates to a plasma generator that can be used as a (chemical vapor deposition) device or an etching device.

[0002]

2. Description of the Related Art In recent years, microwaves have been used in CVD equipment,
A technique for forming a film on a large-area substrate at high speed has come to be used for amorphous silicon and the like. For example, T. T
akahashi, S .; Takamura, T .; Oku
da et al. Appl. Phys. Vol. 53, N
O. 10, October 1982 "Meande
r-line slow-wave antenna
for launching lower hybrid
In "d waves in a plasma", an apparatus for generating plasma by using an electric field of microwaves emitted from a stripline electrode is proposed as described below.

A conventional stripline type plasma generator will be described below. FIG. 6 is a perspective view of a conventional stripline plasma generator, and FIG. 7 is a sectional view thereof. In FIGS. 6 and 7, reference numeral 1 is a coaxial waveguide, and the outer periphery 7 thereof is connected to the conductor plate 2. Here, the coaxial waveguide 1 is provided at two places, and one of the coaxial waveguides 1
Is used for introducing microwaves, and the other coaxial waveguide 1 is used when it is desired to change the propagation direction of microwaves. 3 is a dielectric plate made of polytetrafluoroethylene or the like, and a groove is cut on the surface. Reference numeral 4 denotes a copper wire, and both ends of the copper wire 4 are connected to the inner shaft 6 of each coaxial waveguide 1. The copper wire 4 is bent in a zigzag shape along the groove of the dielectric plate 3 to form a stripline type electrode. In order to protect the copper wire 4, a polytetrafluoroethylene coating 5 is thinly applied on the surface.

In the stripline type plasma generator having the above-mentioned structure, first, by introducing a microwave of 289 MHz and 100 W into one of the coaxial waveguides 1, the pitch thereof is formed on the surface of the stripline type electrode. A microwave standing wave with a wavelength longer than its width is generated. Then, argon gas is ^added thereto in an amount of 2 × 10 ^{−4 to} 3 × 10 ⁻⁴ To.
If rr is introduced, argon gas plasma having a density of about 10 ¹⁰ to 10 ¹¹ cm ⁻³ is generated.

An amorphous silicon film can be formed by introducing SiH ₄ gas instead of argon gas and disposing a heated substrate in front of the stripline type electrode.

[0006]

However, the conventional stripline plasma generator having the above-mentioned structure has a problem that the plasma density in the Z-axis direction is not uniform as shown in FIG. It was Therefore, Si
When the H ₄ gas is introduced to form the amorphous silicon film, the film quality in the Z-axis direction becomes inhomogeneous and it becomes difficult to increase the area.

In order to solve the above-mentioned problems of the prior art, it is an object of the present invention to provide a plasma generator capable of forming a uniform thin film at a high speed on a large-area substrate.

[0008]

In order to achieve the above-mentioned object, the structure of the plasma generator according to the present invention has a vacuum chamber whose inside is kept in a depressurized state, and means for introducing a reaction gas into the vacuum chamber. A means for exhausting the inside of the vacuum chamber, a connecting means for introducing high frequency power into the vacuum chamber, a conductor plate attached to the connecting means in the vacuum chamber, and a conductor plate provided on the conductor plate. A dielectric plate, a stripline type electrode disposed on the dielectric plate and formed by bending a conductor in a zigzag shape, and a magnetic field generating means for generating a magnetic field in the vicinity of the stripline type electrode. It is a thing.

Further, in the above structure, the high frequency is 2.
It is preferably 43 to 2.47 GHz. In the above structure, the vacuum chamber is arranged so as to surround the substrate,
It is preferable to deposit the reaction product on the substrate as the substrate passes through the vacuum chamber.

[0010]

According to the structure of the present invention, the electric field of the microwave radiated from the stripline type electrode when the reaction gas is introduced into the vacuum chamber and the magnetic field from the magnetic field generating means provided in the vicinity of the electric field A uniform plasma can be generated over a wide range by the interaction. Therefore, by moving the substrate in parallel with the stripline type electrode, a uniform thin film can be formed at a high speed on a large-area substrate.

[0011]

EXAMPLES The present invention will be described in more detail below with reference to examples. 1 is a perspective view showing an embodiment of a plasma generator according to the present invention, FIG. 2 is a layout view of electrodes in the plasma generator shown in FIG. 1, and FIG. 3 is a vertical sectional view of the plasma generator shown in FIG. is there.

1 and 3, 10a and 10b are coaxial waveguides, and outer peripheries 21a and 21b thereof are conductor plates 11.
It is connected to the. Here, one coaxial waveguide 10b is used to introduce microwaves, and the other coaxial waveguide 10a is used when it is desired to change the propagation direction of microwaves. In order to cause the coaxial waveguides 10a and 10b to function in this way, the coaxial waveguide 10a is connected to a total reflection terminal and the coaxial waveguide 10b is connected to a microwave power source.

Reference numeral 13 is a dielectric plate made of polytetrafluoroethylene or the like, and a groove is cut on the surface. still,
The dielectric plate 13 has an area of 200 mm × 500 mm and a thickness of 4 mm. Reference numeral 14 denotes a copper wire, and both ends of the copper wire 14 are connected to the inner shafts 20a and 20b of the coaxial waveguides 10a and 10b through the dielectric plate 13, respectively. Further, the copper wire 14 is 180 mm × 440 mm along the groove of the dielectric plate 13.
The strip line type electrode is formed by bending in a zigzag shape with a width of 4 mm and a pitch of 20 mm in a width of mm (see FIG. 2). Thereby, the microwave introduced from the coaxial waveguide 10b can be radiated from the strip line type electrode. In order to protect the copper wire 14, a thin polytetrafluoroethylene coating 18 is provided on the surface.
Has been applied.

In FIG. 1, reference numerals 12a and 12b denote gas pipes. The gas pipes 12a and 12b are arranged on both sides of the stripline type electrode so as to face each other, and a plurality of gases are discharged toward the stripline type electrode. Holes are drilled.

As shown in FIGS. 1, 2 and 3, permanent magnets 15a and 15b are arranged at both ends of the stripline type electrode so that a magnetic field in the Z-axis direction can be generated. ing. Here, the permanent magnets 15a, 15
In b, the opposite surface is magnetized, and the permanent magnet 15a is the N pole,
The permanent magnet 15b is an S pole. In addition, above the microstrip type electrode, a width of 40 mm is provided at a position separated by 30 mm.
A substrate 16 of 0 mm is placed so that it can move in the direction of arrow A.

The components described above are housed inside a vacuum chamber (not shown) provided so as to surround the substrate 16, and the vacuum chamber is provided with an exhaust pump (not shown). In FIG. 1, 17 is an infrared heater for heating the substrate 16.

A plasma generator having the above structure
First, from the coaxial waveguide 10b to 2.45 GHz,
Introducing 300W microwave, stripping
A standing wave is generated on the surface of the in-type electrode. At this time, gas
SiH from the tubes 12a, 12b _Four10mTorr gas
10 if introduced¹¹cm^-3Table high density SiH_Fourplasma
Occurs. In addition, Co-S is applied to the permanent magnets 15a and 15b.
magnetism that generates a region of 875G using m.
If you give power to the microwave of 2.45 GHz
Magnetic field satisfying electron cyclotron resonance (ECR) conditions
22 was generated, and was spread in the Z direction by this magnetic field 22.
Plasma 19 is generated. The density of plasma 19 at this time
The degree becomes uniform in the Z-axis direction as shown in FIG.
The density is 10¹¹cm^-3Stand). Then, in this state, the substrate 1
Heat the 6 to about 300 ° C by the infrared heater 17.
For example, deposit an amorphous silicon film on the substrate 16
You can In this case, the substrate 16 is, for example, 1 mm /
If it is moved in the direction of arrow A (Fig. 1) at a speed of 2 seconds, the film thickness
With a uniformity of ± 5% or less, a thickness of about 0.4 μm is formed on the entire surface of the substrate 16.
An amorphous silicon film can be deposited.

In this embodiment, the permanent magnets 15a and 15b are arranged as the magnetic field generating means so as to face both ends of the stripline type electrode, but the present invention is not necessarily limited to this structure. As shown in FIG. 5, the magnetic field generating means may be configured by disposing a plurality of permanent magnets 24 held by the yoke 23 at a position 5 mm above the substrate 16. In this case, although a plurality of arched magnetic fields 25 are generated, the plasma 26 can spread uniformly on the substrate 16 in the Z-axis direction and form a uniform film.

Further, in this embodiment, 2.45 GH
Although the microwave of z is used, the value is not necessarily limited to this value, and 85 is used for the permanent magnets 15a and 15b.
A magnetic field that satisfies the ECR condition is generated even when a microwave of 2.43 to 2.47 GHz is used so as to have a magnetic force that generates a region of 0 to 900 G. As a result, it is possible to generate plasma that spreads uniformly in the Z direction.

In the present embodiment, the case where the plasma generator is used as the film forming apparatus is described as an example, but the present invention is not necessarily limited to this application.
For example, it can be used in the case of uniformly etching a large-area substrate by setting the introduced gas to a gas suitable for etching with the same configuration.

[0021]

As described above, according to the plasma generator of the present invention, the reaction gas is introduced into the vacuum chamber and the electric field of the microwave radiated from the strip line type electrode and the vicinity thereof are provided. It is possible to generate a uniform plasma over a wide range by the interaction with the magnetic field generated by the magnetic field generating means. Therefore, by moving the substrate parallel to the stripline type electrode, a uniform thin film can be formed on a large-area substrate at high speed, and as a result, productivity can be improved. Further, since the structure is simple, various excellent effects such as reduction of maintenance cost, production cost, etc. can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a plasma generator according to the present invention.

FIG. 2 is a layout view of electrodes in the plasma generator shown in FIG.

FIG. 3 is a vertical cross-sectional view of the plasma generator shown in FIG.

FIG. 4 is a density distribution diagram of plasma generated by an embodiment of the plasma generator according to the present invention.

FIG. 5 is a sectional view showing a magnetic field generating means in another embodiment of the plasma generator according to the present invention.

FIG. 6 is a perspective view of a stripline type microwave plasma generator in the prior art.

7 is a sectional view of the stripline type microwave plasma generator shown in FIG.

FIG. 8 is a density distribution diagram of plasma generated by the stripline type microwave plasma generator shown in FIG.

[Explanation of symbols]

 10a, 10b Coaxial waveguide 11 Conductor plates 12a, 12b Gas introduction pipe 13 Dielectric plate 14 Copper wires 15a, 15b, 24 Permanent magnet 16 Substrate 17 Infrared heater 18 Polytetrafluoroethylene coating 23 Yoke iron

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinichi Mizuguchi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] 1. A vacuum chamber whose inside is maintained in a depressurized state,
Means for introducing a reaction gas into the vacuum chamber, means for exhausting the inside of the vacuum chamber, connecting means for introducing high-frequency power into the vacuum chamber, and conductors attached to the connecting means in the vacuum chamber A plate, a dielectric plate provided on the conductor plate, a stripline type electrode disposed on the dielectric plate and formed by bending a conductor in a zigzag shape, and in the vicinity of the stripline type electrode. A plasma generator comprising at least magnetic field generating means for generating a magnetic field. 2. The plasma generator according to claim 1, wherein the high frequency is 2.43 to 2.47 GHz. 3. The plasma generator according to claim 1, wherein a vacuum chamber is arranged so as to surround the substrate, and a reaction product is attached to the substrate when the substrate passes through the vacuum chamber.