JPH0745537A - Electrode used in plasma CVD apparatus and plasma CVD apparatus - Google Patents

Abstract

(57) [Summary] [Purpose] It is possible to reduce the plasma damage to the film-forming target substrate and the film formed thereon, and to prevent the particles from adhering to the film-forming target substrate and various parts inside the vacuum container, and therefore at a higher speed. Provided are an electrode used in a plasma CVD apparatus capable of forming a film and a plasma CVD apparatus provided with the electrode. A plasma used for a plasma CVD apparatus, which is arranged to face a film formation target substrate S1 and includes a high frequency voltage or DC voltage application electrode portion 31 and a ground electrode portion 32, and is capable of confining plasma. An electrode 3 provided with a source gas supply hole 312a and a radical emission window 321a in the plasma, which forms a chamber 35, and a plasma CVD apparatus including the electrode 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a plasma CVD apparatus for forming a film on a substrate and a plasma CVD apparatus for forming a device using a semiconductor such as a thin film transistor and various sensors using a semiconductor, a solar cell and the like. The electrodes to be processed.

[0002]

2. Description of the Related Art Various types of plasma CVD apparatus are known. As a representative example thereof, a parallel plate type plasma CVD apparatus shown in FIG. 3 will be described. This apparatus has a vacuum container 1 and an electrode 2 which also serves as a substrate holder for mounting a substrate S2 therein and faces this electrode. Electrode 8
Is provided.

The electrode 2 is usually a ground electrode, and
A heater 21 for heating the substrate S2 placed thereon to a film forming temperature is additionally provided. The heater 21 is separated from the electrode 2 when the substrate S2 is heated by radiant heat. The electrode 8 is a power application electrode for applying high-frequency power or direct-current power to the film-forming gas introduced between the electrode 2 and plasma, and in the illustrated example, a high-frequency power source 5 via a matching box 4. Are connected.

In the illustrated example, the electrode 8 has a porous electrode plate 82 in the opening of a gas nozzle 81 which constitutes a part of the electrode.
The electrode plate 82 is provided with a large number of gas supply holes each having a diameter of about 0.5 mm so that the gas supplied from the gas nozzle 81 is entirely discharged from each hole between both electrodes. I am doing it. Such a configuration is suitable for forming a film on a wide area substrate.

An exhaust device 6 is connected to the vacuum container 1 by piping, and a gas supply unit 7 is connected to the gas nozzle 81 by piping. The gas supply unit 7 includes one or more mass flow controllers 711, 712 ...
.. and gas sources 731, 732 ... Supplying a predetermined amount of film forming gas via the on-off valves 721, 722.
·It is included.

According to this parallel plate type plasma CVD apparatus, the film-forming target substrate S2 is placed on the electrode 2 in the vacuum container 1, and the inside of the container 1 is brought to a predetermined vacuum degree by the operation of the exhaust pump 6. From the gas supply unit 7 to the nozzle 81 and the electrode plate 82
The film-forming gas is introduced through the gas supply holes of the. Also,
A high-frequency voltage is applied from the power source 5 to the high-frequency electrode 8, the gas introduced thereby is turned into plasma, and a desired film is formed on the surface of the substrate S2 under this plasma.

[0007]

However, in such a plasma CVD apparatus, since the substrate to be formed is directly exposed to plasma, the film formed on the surface of the substrate is damaged by the high-speed particles in the plasma. There's a problem. Further, there is a problem that fine particles generated by a gas phase reaction in plasma adhere to the film formed on the surface of the substrate or are mixed into the film to deteriorate the film quality. There is a problem that fine particles generated by diffusing outside adhere to various parts inside the vacuum container and contaminate them. The fine particles adhering to various parts in the vacuum container may eventually come off and adhere to the substrate to be treated, so that they have to be removed and cleaned, which is troublesome.

In particular, fine particles are formed by a gas phase reaction,
A film having a high possibility of large growth, for example, an amorphous silicon (a-Si) film made of silane (SiH ₄ ) and hydrogen (H ₂ ), silane and ammonia (NH ₃ ) or nitrogen (N ₂ ) or An amorphous silicon nitride (a-SiN) film is formed from both mixed gases, and an amorphous silicon oxide (a-SiO ₂ ) film is formed from silane and dinitrogen monoxide (nitrous oxide) (N ₂ O) or oxygen (O ₂ ). In the film formation to be formed, the size of the fine particles adhering to the film formed on the surface of the substrate or mixed therein is larger than the film thickness of the formed film, and as a result, the film is an insulating film. In this case, if the cleaning process is performed after the film formation, the fine particles become pinholes, causing insulation failure,
If the film is a semiconductor film, there is a problem that semiconductor characteristics are deteriorated.

Further, such a problem hinders high-speed film formation in which the generation of fine particles increases, and the fine particles hinder stable plasma generation, which may lead to defective film formation. Therefore, the present invention can reduce the plasma damage of the film-forming target substrate and the film formed thereon and can prevent the fine particles from adhering to the film-forming target substrate and each part in the vacuum container, and accordingly, the higher speed film formation is possible. It is an object of the present invention to provide an electrode used in a plasma CVD apparatus and a plasma CVD apparatus including the electrode.

[0010]

An electrode of the present invention for solving the above-mentioned problems is an electrode used in a plasma CVD apparatus and arranged to face a film-forming target substrate, and a high-frequency voltage or direct-current voltage applying electrode portion and ground. A plasma chamber for confining plasma including an electrode portion is formed, and a source gas supply hole and a radical emission window that contributes to film formation in plasma are provided in the plasma chamber.

Further, a plurality of the plasma chambers may be arranged in parallel on the electrode. Further, the plasma CVD apparatus of the present invention for solving the above-mentioned problems, in a vacuum container provided with an exhaust device, turns the introduced source gas into plasma under a predetermined vacuum degree by the operation of the exhaust device, A plasma CVD apparatus for forming a film on a target substrate under plasma, comprising: the electrode having one or a plurality of the plasma chambers; and means for supplying a source gas to the plasma chambers. To do.

[0012]

The electrode of the present invention and the plasma CV provided with the electrode
According to the apparatus D, the source gas supplied from the gas supply hole between the high frequency voltage or DC voltage applying electrode portion of the plasma chamber of the electrode and the ground electrode portion is turned into plasma by discharge by these electrodes, and the plasma is generated. Once confined in the plasma chamber, for example, when silane (SiH ₄ ) gas is used as a source gas, SiH radicals and SiH ₂ radicals that have a short life and cause fine particles are extinguished, and the life is mainly reduced. SiH ₃ radicals that contribute to long film formation are emitted toward the film formation target substrate through the radical emission window of the plasma chamber, and are formed on the substrate.

Further, when a plurality of plasma chambers are arranged in parallel, uniform film formation is performed over a large area of the substrate.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of a plasma CVD apparatus having an electrode 3 for applying electric power for plasma generation, which is an embodiment of the present invention. This plasma CVD apparatus employs an electrode 3 including a high-frequency electrode portion 31 and a ground electrode portion 32 in place of the high-frequency electrode 8 in the conventional apparatus shown in FIG. 3, and the matching box 4 is provided in the electrode portion 31. The high frequency power supply 5 is connected via the. In addition, the electrode 2 which also functions as a substrate holder that supports the substrate S1 is usually a ground electrode.

Other points are substantially the same as those of the apparatus of FIG. The same parts as those in the apparatus of FIG. 3 are given the same reference numerals. 2A and 2B both show the electrode 3 of the device shown in FIG. 1. FIG. 2A is a front view of the electrode surface facing the substrate, and FIG. 2B is along the line XX of FIG. FIG. In the electrode 3, the high frequency electrode section 31 is
A porous electrode plate 312 is provided in the opening of a gas nozzle 311 which constitutes a part of the electrode portion, and a large number of gas supply holes 312a are formed in the electrode plate 312. On the other hand, the ground electrode 32 is arranged so as to surround the high-frequency electrode portion 31, and both the electrode portions 31 and 32 are insulated by the insulator 34 and the insulating spacer 33 having a thickness of about 1 mm.
The ground electrode 32 has an electrode plate 321 facing the film-forming substrate, and a plurality of radical emission slits 321a are formed in parallel therewith. A plurality of plasma chambers 35 are formed from the electrode plate 321 and the electrode plate 312 along the radical emission slits 321a. Inside the high frequency electrode part 31, a gas compensating plate 36 having a plurality of gas through holes 361 is arranged in order to distribute the gas to each gas supply hole 312a of the high frequency electrode plate 312 as uniformly as possible. ing.

According to the plasma CVD apparatus described above, the substrate S1 is placed on the electrode 2 in the vacuum container 1, and the inside of the container 1 is brought to a predetermined vacuum degree by the operation of the exhaust pump 6. Next, the film forming raw material gas is introduced from the gas supply unit 7, and is supplied to each plasma chamber 35 through the through hole 361 of the gas compensating plate 36 and the gas supply hole 312a of the porous electrode plate 312 of the electrode unit 31. At the same time, the high frequency electrode section 31
On the other hand, a high-frequency voltage is applied from the high-frequency power source 5 via the matching box 4, and the gas introduced thereby is turned into plasma. The generated plasma is temporarily confined in the plasma chamber 35. When, for example, silane (SiH ₄ ) gas is used as a source gas, SiH ₃ radicals having a long life, which mainly contribute to film formation, pass through the radical emission slits 321a, Emitted between the electrodes 2, 3 and under this radical the desired film is formed on the surface of the substrate S1 even if it has a relatively large area.

Since the substrate S1 is not exposed to plasma during this film formation, plasma damage to the substrate S1 and the film formed thereon is reduced, and fine particles formed by a gas phase reaction in the plasma are deposited on the surface of the substrate S1. A low defect film can be formed with almost no adhesion to the formed film. In addition, the adhesion of fine particles to each part inside the vacuum container 1 is small, and the frequency of removal and cleaning can be reduced. On the other hand, fine particles adhere to the plasma chamber with high density, which can be efficiently removed by using an etching gas. Moreover, since the gas is less likely to be discharged to the outside of the electrode 3 and adhered to the inner surface of the container 1 is suppressed, it may adhere to the film during the next film formation,
Mixing is suppressed.

An example in which a hydrogenated amorphous silicon (a-Si: H) film is formed by the apparatus of FIG. 1 described above will be described. Film-forming conditions Substrate: 5 inches in diameter Silicon wafer gas: SiH ₄ 100 sccm H ₂ 400 sccm Film-forming temperature: 230 ° C. Film-forming gas pressure: 0.4 Torr Applied power: 400 W (frequency 13.56 MH
z) Each size of the electrodes 2 and 3: 360 mm × 360 mm □ Volume of the plasma chamber 35: 15 mm width × 300 mm length
× depth 20 mm, 10 chambers radical emission slit 321a: 7 mm × 300 mm
(Per plasma chamber) Gas supply hole 312a: Diameter 0.5 mm × 13 (per plasma chamber) Electrode interval: 20 mm (ground electrode portion 321-base body S1)
Surface Distance) In this film formation, the number of film surface defects in the a-Si: H film is about 1 × 10 ¹⁰ per cm ² , and the number of fine particles adhering to the film is about 0.3 μm or more. The number was 5, and the cleaning in the vacuum container had to be performed once for every 50 batches.

When an a-Si: H film was formed under the same conditions using a conventional plasma CVD apparatus, the number of film surface defects was about 1 × 10 ¹² per cm ² , and the number of fine particles adhering to the film was The number of particles having a size of 0.3 μm or more was about 50, and it was necessary to clean the inside of the vacuum container once for every 20 batches. As described above, in the film formation according to the example, both film surface defects and the number of fine particles adhering to the film were smaller and the number of times of cleaning the inside of the vacuum container was smaller than the film formation according to the conventional example.

[0020]

According to the present invention, plasma can be confined in a certain space and radicals mainly contributing to film formation in the plasma can be irradiated to the film-forming target substrate, whereby the film-forming target substrate and the film-forming target substrate formed therewith can be irradiated. It is possible to reduce the plasma damage to the film and to prevent the particles from adhering to the substrate to be film-formed or various parts inside the vacuum container, and therefore, to provide an electrode used in a plasma CVD apparatus that enables high-speed film formation and the electrode. It is possible to provide a plasma CVD apparatus.

When a plurality of plasma chambers are arranged side by side in such an electrode, uniform film formation can be performed over a large area of the target substrate. In addition, the frequency of cleaning and removal of fine particles adhering to the inside of the vacuum container can be reduced, while the fine particles adhering to the plasma chamber can be efficiently removed by using the etching gas. In addition, the gas is less likely to be discharged to the outside of the electrode and is prevented from adhering to the inside of the vacuum container, so that the gas is prevented from adhering to or mixing with the film during the next film formation.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an example of a plasma CVD apparatus that employs an electrode according to an embodiment of the present invention.

2 shows an electrode in the device of FIG. 1, FIG. 2 (A) is a front view showing the electrode surface facing the substrate, and FIG. 2 (B) is a sectional view taken along line XX of FIG. is there.

FIG. 3 is a schematic configuration diagram of an example of a conventional plasma CVD apparatus.

[Explanation of symbols]

 1 Vacuum Container 2 Substrate Holder 21 Heater 3 Electrode 31, 8 High Frequency Electrode Part 311, 81 Gas Nozzle 312, 82 Perforated Electrode Plate 312a Gas Supply Hole 32 Grounding Electrode Part 321 Electrode Plate 321a Radical Emission Slit 33 Insulation Spacer 34 Insulator 35 Plasma Chamber 36 Gas Compensation Plate 361 Gas Through Hole 4 Matching Box 5 High Frequency Power Supply 6 Exhaust Device 7 Gas Supply Section 711, 712 Mass Flow Controller 721, 722 Open / Close Valve 731, 732 Gas Source

Claims (3)

[Claims] 1. An electrode for use in a plasma CVD apparatus, which is arranged to face a film-forming target substrate and includes a high-frequency voltage or DC voltage applying electrode portion and a ground electrode portion to form a plasma chamber for confining plasma. An electrode used in a plasma CVD apparatus, wherein the plasma chamber is provided with a source gas supply hole and a radical emission window that contributes to film formation in plasma. 2. The plurality of plasma chambers are arranged in parallel.
The described electrode. 3. In a vacuum container provided with an exhaust device, the introduced raw material gas is made into plasma under a predetermined vacuum degree by the operation of the exhaust device, and the film-forming target substrate is formed under the plasma. A plasma CVD apparatus for forming a film, comprising the electrode according to claim 1 or 2 and means for supplying a source gas to a plasma chamber in the electrode.