JP3259453B2 - Electrode used for plasma CVD apparatus and plasma CVD apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Various types of plasma CVD apparatuses are known. As a representative example, a parallel plate type plasma CVD apparatus shown in FIG. 3 will be described. This apparatus has a vacuum vessel 1, in which an electrode 2 also serving as a substrate holder in which a substrate S2 is placed and opposed to this electrode. Electrode 9
Is provided.

[0003] The electrode 2 is usually a ground electrode.
A heater 21 for heating the substrate S2 mounted thereon to a film forming temperature is additionally provided. When the substrate S2 is heated by radiant heat, the heater 21 is separated from the electrode 2. The electrode 9 is a power application electrode for applying a high frequency power or a DC power to the film-forming gas introduced between the electrode 2 and the plasma to form a plasma, and in the illustrated example, the high frequency power supply 5 through the matching box 4. Is connected.

[0004] In the illustrated example, the electrode 9 is provided with a porous electrode plate 92 at an opening of a gas nozzle 91 constituting a part of the electrode.
In the electrode plate 92, a number of gas supply holes having a diameter of about 0.5 mm are formed, so that the gas supplied from the gas nozzle 91 is entirely discharged from each hole between the two electrodes. It is. Such a configuration is suitable for forming a film on a large-area substrate.

The vacuum vessel 1 is further connected to a gas exhaust unit 6 by piping, and the gas nozzle 91 is connected to a gas supply unit 7 by piping. The gas supply unit 7 includes one or more mass flow controllers 711, 712,.
··· and gas sources 731, 732 ··· that supply a predetermined amount of film forming gas via opening / closing valves 721 · 722 ···
·It is included.

According to the parallel plate type plasma CVD apparatus, the substrate S2 for film formation is set on the electrode 2 in the vacuum vessel 1, and the inside of the vessel 1 is evacuated to a predetermined degree of vacuum by operating the exhaust device 6. A gas for film formation is introduced from the gas supply unit 7 through the gas supply holes of the nozzle 91 and the electrode plate 92. Further, a high-frequency voltage is applied to the high-frequency electrode 9 from the power supply 5, whereby the introduced gas 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 a substrate to be formed is directly exposed to plasma, a film formed on the surface of the substrate is damaged by high-speed particles in the plasma. There's a problem. Further, there is a problem that fine particles generated by a gas phase polymerization reaction in plasma adhere to a film formed on the substrate surface or are mixed therein, thereby deteriorating the film quality.
There is a problem in that the fine particles generated by the plasma being diffused outside the regions opposed to both electrodes adhere to and contaminate the respective parts in the vacuum vessel. The fine particles adhering to each part in the vacuum container may eventually peel off and adhere to the substrate to be processed.

In particular, fine particles are formed by a gas phase reaction,
It is highly likely that the film grows greatly, for example, an amorphous silicon (a-Si) film is formed from silane (SiH ₄ ) and hydrogen (H ₂ ), and silane and ammonia (NH ₃ ) or nitrogen (N ₂ ) or An amorphous silicon nitride (a-SiN) film is formed from the mixed gas, 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 for forming the film, the size of the fine particles adhering to or mixed into the film formed on the substrate surface is larger than the film thickness of the film to be formed. When the film is a film, if the cleaning treatment is performed after the film formation, there is a problem that a portion of the fine particles becomes a pinhole to cause insulation failure, and if the film is a semiconductor film, the semiconductor characteristics are deteriorated.

Further, such a problem hinders high-speed film formation in which the generation of fine particles increases, and hinders stable generation of plasma by the fine particles, which may result in poor film formation. Therefore, the present invention can reduce the plasma damage of the substrate to be formed and the film formed thereon, and can prevent the fine particles from adhering to the substrate to be formed and various parts in the vacuum vessel. It is an object of the present invention to provide an electrode used in a plasma CVD apparatus that can further suppress generation thereof and thus enable high-speed film formation, and a plasma CVD apparatus including the electrode.

[0010]

Means for Solving the Problems The electrode of the present invention to solve the problems described above is used in the plasma CVD apparatus, an electrode disposed opposite to the film-forming target substrate, a voltage application for applying a high frequency voltage or a direct voltage Including an electrode part and a ground electrode part,
The voltage applying electrode section is a gas for introducing a plasma source gas.
Electrode and a voltage applying electrode plate provided in the opening thereof.
Wherein the ground electrode portion is the electrode plate for voltage application.
Including a grounding electrode plate that is opposed to
The space between the electrode plate for voltage application and the electrode plate for grounding.
The space is divided into several parts to confine the plasma.
Number of plasma chambers are juxtaposed, and the voltage applying electrode
The plate supplies plasma source gas to each of the plasma chambers.
And a gas supply hole for supplying the ground electrode.
The plate releases radicals in the plasma from each of the plasma chambers
Having a radical emission window for
Through the gas supply holes of the electrode plate for voltage application.
For distributing the plasma source gas to each plasma chamber,
A gas compensator with a number of gas holes is arranged.
The above-mentioned step facing the film formation target substrate of the above-mentioned grounding electrode plate
A part outside the plasma chamber, other than the radical release window.
A gas discharging portion for discharging a film-forming gas is provided in the portion .

[0011] The plasma CVD apparatus of the present invention to solve the above problems, the electrode having the plasma chamber, the Gasunozu supplies a plasma source gas into said plasma chamber
A gas supply means containing a gas , and a means for supplying a gas for film formation to the gas discharge part of the electrode.

As the gas used for the film formation, for example, in forming an a-Si: H film, H ₂ is used as a plasma source gas and SiH ₄ is used as a film formation gas.
In forming the a-SiN film, NH ₃ or N ₂ or a mixed gas of both is considered as the plasma source gas, and SiH ₄ is considered as the film forming gas. In forming the SiO ₂ film, N ₂ O is used as the plasma source gas. Alternatively, O ₂ and SiH ₄ can be considered as a film forming gas.

[0013]

The electrode of the present invention and a plasma CV provided with the electrode
According to apparatus D, a plasma chamber is formed at the electrode.
Voltage application of high frequency voltage or a direct voltage application electrode unit electrodeposition are
Between the ground electrode plate of the electrode plate and the ground electrode section, it does not contribute to film formation alone plasma source gas voltage from the gas nozzle
The gas is supplied through a gas supply hole of the electrode plate for application , the gas is turned into plasma by a discharge between the electrode plates, and the generated radicals are emitted toward the substrate to be formed through the radical emission window of the plasma chamber. Is done. On the other hand, a gas that can contribute to film formation by itself is emitted from the emission portion of the film forming gas toward the substrate, and the gas reacts with the radicals on the substrate surface to form a film on the substrate.

A plurality of the plasma chambers are provided in parallel.
And the plasma nozzle has a plasma
Gas compensator for distributing raw material gas
Therefore, uniform film formation over a large area of the substrate is performed without significantly complicating the electrode structure .

[0015]

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 power for plasma generation, which is an embodiment of the present invention. This plasma CVD apparatus employs an electrode 3 comprising a high-frequency electrode section 31 and a ground electrode section 32 in place of the high-frequency electrode 9 in the conventional apparatus shown in FIG. The high frequency power supply 5 is connected via the power supply. The gas supply unit 8 for film formation is connected to the ground electrode unit 32. The gas supply unit 8 includes a film forming gas discharge line 321b to be described later.
, And one or more mass flow controllers 811, 812,..., On-off valves 821, 82
.. And gas sources 831, 832. Further, the electrode 2 also serving as a base holder for supporting the base S1 is usually a ground electrode.

The other points are substantially the same as those of the apparatus shown in FIG. Components that are the same as those in the apparatus of FIG. 3 are given the same reference numerals. 2A and 2B show the electrode 3 of the apparatus shown in FIG. 1, wherein FIG. 2A is a front view of the electrode surface directed to the substrate, and FIG. 2B is along the line XX in FIG. It is sectional drawing. In the electrode 3, the high-frequency electrode section 31
A porous electrode plate 312 is provided at an opening of a gas nozzle 311 constituting 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 part 32 is disposed so as to surround the high-frequency electrode part 31, and the two electrode parts 31 and 32 are insulated by an insulator 34 and an insulating spacer 33 having a thickness of about 1 mm. The ground electrode portion 32 is an electrode plate 321 facing the substrate on which the film is to be formed.
, And a plurality of radical emission slits 321a are formed in parallel. A plurality of plasma chambers 35 are formed from the electrode plate 321 and the electrode plate 312 along the radical emission slit 321a. Inside the high-frequency electrode section 31, in order to distribute gas as uniformly as possible to each gas supply hole 312a of the porous electrode plate 312,
The gas compensating plate 36 in which a plurality of gas holes 361 are formed is arranged. Further, along the surface of the electrode plate 321 of the ground electrode portion 32 facing the base S1, the slit 321a is formed.
A plurality of gas discharge gas lines 321b are formed alternately and in parallel with the slits 321a, and a plurality of film formation gas discharge holes 321c are formed in each line. Each gas line 321b is connected to the film forming gas supply unit 8 by a pipe.

According to the plasma CVD apparatus described above,
The substrate S1 is placed on the electrode 2 in the vacuum vessel 1, and the inside of the vessel 1 is evacuated to a predetermined degree of vacuum by operation of the exhaust device 6. Next, a plasma source gas that does not contribute to film formation by itself is introduced from the gas supply unit 7, and the gas supply holes 312 a of the porous electrode plate 312 of the electrode unit 31 and the through holes 361 of the gas compensator 36.
And is supplied to each plasma chamber 35. At the same time, a high-frequency voltage is applied to the high-frequency electrode unit 31 from the high-frequency power supply 5 via the matching box 4, whereby the introduced gas is turned into plasma, and the generated radicals pass through the radical release slits 321 a and pass through the electrodes 2, 3. 3
Released during On the other hand, a film forming gas that can contribute to film formation by itself is introduced from the gas supply unit 8, passes through the gas line 321 b of the porous electrode plate 321 of the electrode unit 32, and the film forming gas supply hole 321 c, and the electrode 3 and the substrate Released between S1 and S1. Under these radicals and gases, a desired film is formed on the surface of the substrate S1, even if it has a relatively large area.

During the film formation, the substrate S1 is not exposed to the plasma, so that the plasma damage of the substrate S1 and the film formed thereon is reduced, and the fine particles formed by the gas-phase polymerization reaction in the plasma reduce the surface of the substrate S1. Hardly adheres to the film formed on the substrate. In addition, by supplying a gas that can contribute to film formation by itself to the substrate surface, generation of fine particles due to a gas phase polymerization reaction can be further suppressed, and a low defect film can be formed.

Further, the amount of fine particles adhering to each part in the vacuum vessel 1 is small, and the frequency of removal and cleaning can be reduced. On the other hand, in the plasma chamber, gas that does not contribute to film formation by itself is turned into plasma, so contamination by fine particles is reduced,
A stable plasma is maintained. A specific example in which an a-SiN: H film and an a-Si: H film are formed by the above-described apparatus of FIG. 1 will be described.

Example 1 (a-SiN: H film formation) Substrate: 5 inches in diameter Silicon wafer gas: 100 sccm of SiH ₄ (film forming gas) NH ₃ 600 sccm (plasma raw material gas) Film forming temperature: 280 ° C. Film forming gas Pressure: 0.8 Torr Applied power: 600 W (frequency 13.56 MH
z) Example 2 (a-Si: H film formation) Substrate: 5 inch diameter Silicon wafer gas: SiH ₄ 100 sccm (film forming gas) H ₂ 400 sccm (plasma raw material gas) Film forming temperature: 230 ° C. Film forming gas pressure : 0.4 Torr Applied power: 400 W (frequency 13.56 MH
z) In addition, both Examples 1 and 2 were carried out using the apparatus shown in FIG.

Each size of electrodes 2 and 3: 360 mm × 3
60mm □ Volume of plasma chamber 35: width 15mm x length 300mm
X depth 20mm, 10 chambers Radical release slit 321a: 7mm x 300mm
(Per plasma chamber) Plasma source gas supply hole 312a: 0.5 mm in diameter x 1
3 (per plasma chamber) Film forming gas discharge hole 321c: diameter 0.5 mm × 1
17 Electrode spacing: 20 mm (ground electrode part 321-substrate S1
(Distance between surfaces) Regarding the film formation under the same conditions as the film formation according to the examples 1 and 2 and the conventional apparatus performed under the same conditions, the number of film surface defects per 1 cm ^{2 and} the size of 0.3 μm or more adhered to the film. The results of measuring the number of fine particles and the number of film forming batches that can be performed for one cleaning in the vacuum vessel are shown below. Example 1 Example Comparative example Number of film surface defects 1 × 10 ¹¹ 1 × 10 ¹³ Number of adhered fine particles About 5 About 50 Batches / cleaning 50 20 Example 2 Example Comparative example Number of film surface defects 1 × 10 ¹⁰ 1 × 10 ¹² Number of attached fine particles Approx. 5 Approximately 50 Number of batches / cleaning 50 20 As described above, the number of film surface defects and the number of attached fine particles to the film are smaller in the film formation in Examples 1 and 2 than in the film formation in Comparative Example. The number of times of cleaning the inside of the vacuum vessel could be reduced.

[0022]

According to the present invention, the plasma is once confined in the plasma chamber, and radicals mainly contributing to the film formation in the plasma can be irradiated to the film formation target substrate. A gas that can reduce the plasma damage of the film, suppresses the attachment of fine particles to the substrate to be processed and various parts in the vacuum vessel, and contributes to the film formation by a reaction on the substrate surface by radical excitation By being supplied to the surface, it is possible to further suppress the generation of fine particles due to a gas phase polymerization reaction, and to provide an electrode used for film formation by a plasma CVD method, which enables film formation by a plasma CVD method at a higher speed than before, and to provide the electrode. A plasma CVD apparatus can be provided.

In addition, a plurality of the plasma chambers are provided in parallel.
And the plasma nozzle has a plasma
Gas compensator for distributing raw material gas
Therefore, it is possible to form a uniform film over a large area of the substrate on which the film is to be formed without significantly complicating the electrode structure . In addition, the frequency of cleaning and removal of fine particles adhering to the vacuum vessel can be reduced. In the plasma chamber, gas that does not contribute to film formation by itself is turned into plasma, so contamination by fine particles is reduced and stable plasma is maintained. can do.

[Brief description of the drawings]

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

2A and 2B show electrodes in the apparatus shown in FIG. 1; FIG. 2A is a front view showing an electrode surface directed to a base; FIG. 2B is a cross-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]

DESCRIPTION OF SYMBOLS 1 Vacuum container 2 Substrate holder 21 Heater 3 Electrode 31, 8 High frequency electrode part 311, 81 Gas nozzle 312, 82 Porous electrode plate 312a Plasma raw material gas supply hole 32 Ground electrode part 321 Electrode plate 321a Radical release slit 321b Gas release gas line 321c Film forming gas discharge hole 33 Insulating spacer 34 Insulator 35 Plasma chamber 36 Gas compensator 361 Gas through hole 4 Matching box 5 High frequency power supply 6 Exhaust device 7 Plasma source gas supply unit 8 Film formation gas supply unit 711, 712, 811 , 812 Mass flow controller 721, 722, 821, 822 On-off valve 731, 732, 831, 832 Gas source

Claims (3)

(57) [Claims] An electrode which is used in a plasma CVD apparatus and is opposed to a substrate on which a film is to be formed. The electrode includes a voltage application electrode section for applying a high frequency voltage or a DC voltage and a ground electrode section.
Only, the voltage applying electrode section is for introducing the plasma raw material gas.
Gas nozzle and voltage application electrode provided in its opening
And the ground electrode portion is provided with the voltage applying voltage.
Includes a grounding electrode plate facing the electrode plate with a space
Between the electrode plate for voltage application and the electrode plate for grounding.
The space is partitioned into spaces to confine the plasma
A plurality of plasma chambers are arranged side by side,
The electrode plate is placed in each of the plasma chambers,
And a gas supply hole for supplying
The electrode plate removes radicals in the plasma from each of the plasma chambers.
A radical release window for releasing the gas;
In the nozzle through the gas supply hole of the voltage applying electrode plate
To distribute the plasma source gas to each of the plasma chambers
A gas compensator having a plurality of gas through holes is arranged,
Further, before the grounding electrode plate is turned to the substrate for film formation.
A portion outside the plasma chamber, the portion being outside the radical release window.
A gas discharge section for discharging the film forming gas is
An electrode for use in a plasma CVD apparatus, characterized in that the electrode is used. 2. A discharge unit for discharging a film-forming gas, comprising:
Provided in a region other than the radical release window of the electrode plate,
The electrode according to claim 1, wherein the electrode is a gas release gas line having a film formation gas release hole . 3. An electrode according to claim 1, wherein said gas is used for supplying a plasma raw material gas to a plasma chamber in said electrode.
A plasma CVD apparatus comprising: gas supply means including a nozzle ; and means for supplying a gas for film formation to the gas discharge part of the electrode.