JP2003188106A - Plasma process apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma process apparatus which has high-performance and uniform processability. <P>SOLUTION: The plasma process apparatus is equipped with a processing chamber 5, a gas intake 7 which introduces material gas into the processing chamber 5, discharge electrodes 2a and 2b, and an AC power source 1 with a plurality of terminals. The plurality of terminals are composed of output terminals and terminals to have a floating potential other than the output terminals. The discharge electrodes 2a and 2b are composed of discharge electrodes connected to the output terminals and discharge electrodes which are held at a ground potential without being connected to the terminals and having the floating potential other than the discharge electrodes connected to the output terminals. The discharge electrodes connected to the output terminals and the discharge electrodes and having the ground potential without being connected to the terminals to have the floating potential can be switched. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a plasma process apparatus, and more specifically, plasma chemistry using a plasma-enhanced chemical vapor deposition method used for manufacturing a semiconductor film or an insulating film in the electronic industry. Vapor deposition equipment,
A dry etching device for performing dry etching for forming a thin film pattern of a semiconductor film or a conductor film, and an asher device for removing a resist used for forming a thin film pattern,
The present invention relates to a plasma process apparatus that decomposes gas by plasma to form or process a thin film.

[0002]

2. Description of the Related Art A method of forming a semiconductor film using plasma to manufacture electronic devices such as integrated circuits, liquid crystal displays, and amorphous solar cells, so-called plasma-enhanced chemical vapor deposition (CVD).
Method) is used for manufacturing various electronic devices because of its excellent simplicity and operability.

The form of the apparatus using the plasma CVD method (plasma chemical vapor deposition apparatus, hereinafter plasma CVD apparatus) is generally as follows, and based on FIG. 6 (perspective view) and FIG. 7 (cross-sectional view). explain.

The processing chamber (vacuum container) 5 is used to form a closed space, in which the electrodes 2a are electrically insulated from each other and are composed of two conductor plates arranged in parallel at opposing positions.
A plasma 11 is generated between 2b, and a material gas is caused to flow therein to decompose and dissociate the gas, and a processing substrate (deposition substrate) 4 such as silicon or glass attached to one electrode 2b.
A semiconductor film or the like is formed on the above.

As a means for generating the plasma 11 for decomposing the material gas for film formation, electric energy such as high frequency having a frequency of 13.56 MHz is usually used. That is, one conductor plate electrode 2b is set to the ground potential, and a voltage is applied to the other opposing electrode 2a to generate an electric field between both conductor plates, and a plasma discharge 11 is generated as a glow discharge phenomenon by the dielectric breakdown phenomenon. To do.

The electrode to which a voltage is applied, that is, the electrode 2a for applying electric energy is called a cathode electrode or a discharge electrode, and a large electric field is formed in the vicinity thereof,
The electrons in the plasma 11 accelerated there accelerate the dissociation of the material gas and generate radicals 12.

The portion of the discharge 11 where a large electric field is formed near the cathode electrode 2a is called the cathode sheath portion. The radicals 12 generated at or near the cathode sheath portion diffuse to the film-forming substrate 4 on the electrode 2 at the ground potential, where they are deposited on the film surface to grow the film. The electrode at the ground potential is called the anode electrode 2b.

Such a plasma CVD method is widely used in various industries. For example, in the manufacturing process of active drive type liquid crystal displays, TFT (Thin F
A switching element called an “ilmTransistor” is manufactured, and in the TFT, a gate oxide film such as an amorphous silicon film or silicon nitride, which is a constituent part of the switching element, plays an important role. In order for each film to play its role, a technique for efficiently forming a high quality film is indispensable.

Similar to the plasma CVD apparatus, the dry etching apparatus for etching the thin film and the asher apparatus for removing the resist are similar to the plasma CVD apparatus by simply replacing the material gas with the etching gas. It is known as a plasma process device.

The method of generating the plasma 11 and the generation of radicals are similar mechanisms, and the radicals reaching the processing substrate 4 remove the thin film and the like.

The difference from the plasma CVD apparatus is not only the presence of radicals but also the fact that physical sputtering by ion bombardment from plasma and energy injection into the processing substrate 4 are utilized for the etching operation.

The electric energy source (hereinafter referred to as the power source 1) of these plasma process apparatuses is as described above.
A high frequency having a normal frequency of 13.56 MHz is used to generate plasma 11, and thereby film formation or etching is performed, so that the material gas is dissociated to generate radicals 12. FIG. 8 shows the configuration of a commonly used power supply 1.

A high frequency of 13.56 MHz is generated in the signal source 21, and the high frequency of 13.56 MHz is amplified by the amplifier 22 of one stage or a plurality of stages so that a desired output level can be obtained. The output impedance of this amplifier 22 is usually 50Ω.

However, the electrode 2a of the plasma process apparatus
Is usually far from 50Ω as an input impedance, so a matching circuit 24 for performing impedance conversion is inserted therebetween. There are various types of matching circuits 24, and they are composed of a large variable capacitance and a large variable inductance. Then, the output of the matching circuit 24 is directly connected to the electrode 2a. The electrode 2bha is grounded.

[0015]

However, there is a limit to the film-forming apparatus that has been established so far, and when a large-area electronic device such as a liquid crystal display / amorphous solar cell is manufactured, a high-quality film is often formed on the film-forming substrate 4. Problems have arisen when making films with good uniformity.

A method for forming a high quality film on the film formation substrate 4 is disclosed in, for example, Japanese Patent Laid-Open No. 11-144892.
The following are proposed.

In this method, as shown in FIG. 9 (perspective view) and FIG. 10 (cross-sectional view), the electrode 2 having a convex surface is used.
By providing a plurality of a and 2b and disposing the film formation substrate 4 at a position away from the electrode 2, a lateral electric field is formed and high quality film formation is possible.

In this way, the film-forming substrate 4 is connected to the electrodes 2a and 2b.
Since the film formation substrate 4 is not exposed to the plasma 11 by being installed at a position away from, the film formation surface of the thin film is not deteriorated by ion bombardment and a high quality film can be formed.

However, in this method, the unevenness of the electrode surface causes a thickness distribution of the film formed on the film formation substrate 4.

That is, the film thickness becomes thicker when the distance between the film forming substrate and the electrode surface is smaller, and becomes smaller when the distance between the film forming substrate and the electrode surface is far. Further, if the distance between the electrode and the film-forming substrate is not sufficient according to the repeating distance of the cathode electrode in which radicals are often generated in the vicinity, a thickness distribution of the film to be formed will occur. That is, the discontinuous distribution of the radical source must be relaxed by the diffusion of radicals, but for that purpose, it is necessary to secure a sufficient distance between the electrode and the film formation substrate.

That is, a method for forming a high quality film with good uniformity has not been established yet. Further, if the dry etching apparatus and the asher apparatus are also configured in the same manner as the apparatus described in JP-A-11-144892, the plasma generating section and the ion bombardment control section can be controlled separately. That is, it is possible to attach the third electrode to the rear of the processing substrate and perform it independently of the plasma generation of the ion bombardment control, and the controllability of the parameters can be improved. However, in this case, there is the same drawback that the amount of radicals incident on the substrate becomes non-uniform in the plane.

Further, a sputtering device is used instead of the plasma process device.
Similarly to Japanese Patent Laid-Open No. 11-144892, it is said that a cathode electrode and an anode electrode are installed at a position apart from the substrate to improve the quality of the sputtered film.
In the case of this device, it is said that it is effective to switch the cathode electrode and the anode electrode in order to improve the quality of the sputtered film. However, a specific method is shown by which means the electrodes are switched. Absent.

That is, as a whole, a plasma apparatus having high workability and good uniformity has not been established yet.

Therefore, an object of the present invention is to provide a plasma device which has high workability and high uniformity.

[0025]

A plasma processing apparatus according to a first aspect of the present invention includes a processing chamber, a gas inlet for introducing a material gas into the processing chamber, a plurality of discharge electrodes, and a plurality of discharge electrodes. The present invention relates to a plasma process device including an AC power supply having a terminal. The plurality of terminals include an output terminal and a terminal having a floating potential other than the output terminal. The plurality of discharge electrodes are a discharge electrode connected to the output terminal and a discharge electrode connected to a ground potential without being connected to a terminal having a floating potential other than the discharge electrode connected to the output terminal. Composed of. It is possible to switch between a discharge electrode connected to the output terminal and a discharge electrode not connected to the floating potential terminal and having a ground potential.

A plasma process apparatus according to a second aspect of the present invention is the plasma process apparatus according to the first aspect, wherein the output of the AC power supply is a pulse, and each pulse is connected to the output terminal. Discharge electrode,
It is characterized in that it is switched to the discharge electrode having the ground potential without being connected to the terminal having the floating potential.

A plasma process apparatus according to a third aspect is the plasma process apparatus according to the first aspect or the second aspect, characterized in that the AC power source has a matching circuit at each of the plurality of terminals.

A plasma processing apparatus according to a fourth aspect of the present invention is a processing chamber, a gas inlet for introducing a material gas into the processing chamber, a plurality of discharge electrodes, and an AC power source having a plurality of terminals. , A processing substrate holder facing the discharge electrode. The plurality of terminals include an output terminal and a terminal having a floating potential other than the output terminal. The plurality of discharge electrodes are a discharge electrode connected to the output terminal and a discharge electrode connected to a ground potential without being connected to a terminal having a floating potential other than the discharge electrode connected to the output terminal. Composed of. During the processing, the discharge electrode connected to the output terminal and the discharge electrode connected to the ground potential without being connected to the terminal having the floating potential are switched. The repeating distance of the discharge electrode connected to the output terminal is shorter than the distance between the discharge electrode and the surface to be processed of the substrate attached to the substrate holder during processing.

A plasma process apparatus according to a fifth aspect of the present invention is the plasma process apparatus according to the fourth aspect, wherein the output of the AC power supply is a pulse, and each pulse is connected to the output terminal. Discharge electrode,
It is characterized in that the discharge electrode having the ground potential is switched without being connected to the terminal having the floating potential.

A plasma process apparatus according to a sixth aspect of the present invention is the plasma process apparatus according to the fourth or fifth aspect, characterized in that the AC power supply has a matching circuit at each of the plurality of terminals.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be specifically described below with reference to the drawings.

Embodiment 1 An apparatus actually manufactured based on the present invention will be described.

In this embodiment, FIGS. 1 and 2 (perspective view).
And a plasma CVD apparatus of the type shown in FIG. 3 (cross section) was used.

A mechanical booster pump and a rotary pump for discharging gas were attached and used as the gas discharging portion.

The material gas used is SiH ₄ (1000s
ccm) and H ₂ (1500 sccm) were used.

The material gas was introduced through the gas inlet 6 arranged in the inter-electrode insulating portion 3, as shown in FIGS. 2 and 3. Frequency 1 to apply electrical energy
A high frequency power supply of 3.56 MHz was used.

As the electrode part, 5 mm × 10 mm × 95
Prepared a number of cm stainless steel rods, and the size was 1m x 1m.
The depth is 10 mm and the width is 5 m so that the stainless steel rod is fitted in the thickness direction of the Teflon (R) plate with a thickness of 20 mm.
m, the groove having a distance of 5 mm was formed at a distance of 5 mm, and a stainless rod was inserted into the groove. The stainless steel rods are grouped by connecting them alternately so that electric discharge occurs between adjacent rods.
Two groups (electrode 2a 'and electrode 2b') were formed.

As the film-forming substrate 4, a glass substrate having a thickness of 1.1 mm was placed at a position apart from the electrodes 2a 'and 2b'.

Although not shown in FIGS. 2 and 3, the film formation substrate 4 is heated (at the film formation substrate temperature of 200 ° C.).
In order to hold the film formation substrate 4, the film formation substrate holder 9 holding the film formation substrate 4
A heater is installed behind.

As the power source, the one shown in FIG. 1 was used. That is, the outputs from the signal source 21 and the amplifier 22 are pulsed, and the system changeover switch 2 is provided for each pulse.
The output is switched to 2 systems at 3. The pulse width is 50 ms and the pulse interval is 50 ms.

A matching circuit 24 is provided for each system, one group of the electrodes 2 in the processing chamber 5 is connected to each matching circuit 24, and the matching circuit 24 and the electrodes 2a 'and 2b' are connected.
An output / ground changeover switch 25 is provided between the two.

The system changeover switch 23 and the output / ground changeover switch 25 are synchronized, and when the system changeover switch 23 operates so as to output an output to one system, the output / ground changeover switch 25 of the system is matched. The output of the circuit 24 and the electrodes 2a 'and 2b' in the processing chamber 5 are directly connected,
At the same time, the output / grounding changeover switch 25 of the other system connects the electrodes 2a 'and 2b' in the processing chamber 5 to the ground potential portion.

That is, when the output is applied to the electrode 2a 'group to serve as the cathode electrode 2a, the electrode 2b' group is connected to the ground potential and serves as the anode electrode 2b. When the output pulse is switched, on the contrary, an output is made to the electrode 2b 'group to become the cathode electrode 2a, and the electrode 2a' group is connected to the ground potential and becomes the anode electrode 2b.

With respect to the apparatus of FIGS. 1, 2 and 3, the gas pressure was 80 Pa, the high frequency power was 500 W, and the film thickness distribution of the produced amorphous silicon film was evaluated. It was

[0045]

[Table 1]

On the other hand, for comparison, a similar operation test was conducted on a device in which a part of the power source of the device of FIG. 2 is as shown in FIG. This device has the following exceptions:
It is similar to the device described above.

The electrode 2a 'group is the cathode electrode 2a and the electrode 2
The output of the power supply 1 was connected so that the b ′ group became the anode 2b, the output of the power supply 1 was always constant, and the electrode function was fixed with time.

As shown in Table 1, in the case of the apparatus shown in FIGS. 1, 2 and 3, the distance 32 between the electrode and the film-forming substrate is 15-2.
Within 5 mm, the in-plane uniformity of film thickness was all ± 5% or less, which was good. Here, the in-plane uniformity of the film thickness is
(Maximum film thickness-minimum film thickness) / (maximum film thickness + minimum film thickness) x 1
It is defined by 00.

On the other hand, in the case of the apparatus shown in FIGS. 8, 2 and 3, the uniformity becomes ± 5% or less only when the electrode-deposition substrate distance 32 is 25 mm. However, the film formation rate was as slow as 3Å / ms and the throughput was a little low. As a result,
The apparatus shown in FIGS. 2 and 3 realized film formation with high uniformity at a high film formation rate.

The results of Table 1 are shown in FIG. 4 and FIG.
This will be described in more detail. In the case of FIG. 4 (a) in Table 1, the cathode electrode 2a appears in both the electrode 2a 'group and the electrode 2b' group, and the repeating distance of the electrode 1 to be the cathode electrode 2a is 10 mm.

The radicals 12 generated in the vicinity of the cathode electrode 2a have a substantially uniform distribution when scattered over a repeating distance 31 of the electrode position which becomes the cathode electrode 2a. Therefore, in the case of FIG. 4, the distance 32 between the electrode and the film formation substrate is 15 to
The film was formed with good uniformity in all cases of 25 mm.

On the other hand, in the case of FIG. 5 (B) of Table 1, the cathode electrode 2a appears only in the electrode 2a 'group, and the repeating distance 31 of the electrode position which becomes the cathode electrode 2a is 20 m.
m. Therefore, the electrode-deposition substrate distance 32 is 1
In the case of 5 to 20 mm, the nonuniformity became large.

However, the distance 32 between the electrode and the film-forming substrate is set to 25.
In mm, although the throughput was a little low, it could be used sufficiently as an apparatus. At this time, the cathode electrode 2a appears at a repeating distance 31 of 20 mm.
That is, generally, when the distance 32 between the electrode and the film formation substrate is longer than the repeating distance 31 of the electrode 1 which becomes the cathode electrode 2a within the processing time, the film can be formed with good uniformity.

Further, the above-mentioned embodiment is a plasma CV.
Although it has been applied to the D apparatus, the present invention is not limited to this, and is widely applicable to a plasma processing apparatus using plasma 11 such as a dry etching apparatus and an ashing apparatus. For example, when applied to a dry etching apparatus, the gas species used are CF ₄ , SF ₆ , C
It may be changed to l ₂ , HCl, BCl ₃ , O ₂ or the like. As a dry etching apparatus, an electrode for controlling ion bombardment is separately attached to the back surface of the film formation substrate 4.

In the embodiment described above, the matching circuit 24 is provided for each system. When the impedances of the electrode groups 2a 'and 2b' are not equal, by providing the matching circuit 24 for each system in this way, equal output can be obtained for each electrode (group).
It can be applied to 2a 'and 2b'. On the other hand, each electrode group 2
When the impedances of a ′ and 2b ′ are substantially equal to each other, even if the matching circuit 24 is not provided for each system but the common matching circuit 24 is provided and the system changeover switch 25 is provided after the matching circuit 24, Equal output is applied to each electrode (group) 2a'.2
applied to b '.

In the above embodiment, the frequency of the power source 1 is 13.56 MHz, but the frequency is not limited to this. The power supply form as described above is effective
It is effective for all high-frequency power sources other than waveguide-type microwaves that have no inner conductor, for example, a frequency of 1 kHz.
As described above, the same function can be realized for those of 100 MHz or less.

The function of the anode electrode 2b needs to be at the ground potential. If it is in the floating potential or high impedance state instead of the ground potential, no discharge occurs between the cathode electrode 2a.

When the electrode to which the output is applied (or a plurality of electrodes) is the cathode electrode 2a, it is necessary to use any one of the other electrodes as the anode electrode 2b. It is necessary to make the electrode of the ground potential. In the case of the power supply 1 described above, this function is satisfied, and the desired result is obtained.

The term "ground potential" used above means
It does not have to be a perfect ground potential, and there is no problem if it can be regarded as a ground potential with a certain resistance value.

The electrode material is not limited to stainless steel, but a metal such as aluminum may be used. The inter-electrode insulating material is not limited to Teflon (R), and a ceramic material such as alumina may be used.

The embodiments disclosed this time are to be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

[0062]

According to the present invention, it is possible to realize a plasma processing apparatus capable of performing film formation and processing on a film formation substrate with high quality and uniformity.

In order to manufacture an active drive type liquid crystal display, T using an amorphous silicon film or the like is used.
Although it is necessary to have an FT section, since the processing substrate has a size of several tens of cm square or more, a high quality TFT substrate can be manufactured by realizing high quality and uniform film formation by such means. Becomes

Alternatively, in fields other than liquid crystal displays, the same effect can be obtained as a film forming apparatus for amorphous silicon which is a light conversion layer of an amorphous silicon solar cell which is also formed by the plasma CVD method.

Further, in the case of manufacturing an active drive type liquid crystal display, when the thin film pattern is formed by dry etching, by using this plasma process apparatus, not only high controllability of parameters can be realized, but also at the same time. It is possible to secure a uniform etching rate in the plane. Further, by applying it to the asher device, it is possible to realize uniform removal of the resist in the plane.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a power supply used in a plasma processing apparatus of the present invention.

FIG. 2 is a perspective view of a plasma processing apparatus used in the present invention.

FIG. 3 is a cross-sectional view of the plasma processing apparatus of the present invention.

FIG. 4 is a diagram for explaining the mechanism when the plasma processing apparatus of the present invention is used.

FIG. 5 is a diagram drawn as a comparison for explaining the mechanism of the plasma process apparatus according to the present invention.

FIG. 6 is a perspective view of a conventional plasma process apparatus.

FIG. 7 is a sectional view of a conventional plasma process apparatus.

FIG. 8 is a conceptual diagram for explaining a power source of a conventional plasma process apparatus.

FIG. 9 is a perspective view of a conventional plasma processing apparatus.

FIG. 10 is a sectional view of a conventional plasma process apparatus.

[Explanation of symbols]

1 power supply, 2a cathode electrode, 2b anode electrode,
2a '1st electrode group, 2b' 2nd electrode group, 3 inter-electrode insulating part, 4 processing substrate, 5 processing chamber, 6 gas inlet,
7 gas retention part, 8 introduction terminal, 9 processing substrate holder, 11 plasma, 12 radical, 13 gas supply part, 14 gas flow, 15 film formed, 21 signal source, 22 amplifier, 23 system selector switch, 24 matching Circuit, 25 output / grounding switch, 31 Repeating distance of electrode position to which output of high frequency power supply is connected, 32
Electrode-treated substrate distance.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4K030 AA06 BA30 CA06 FA01 JA03                       JA20 KA30                 5F004 BA06 BB11 BB13 BD01 BD04                       CA03 DA01 DA04 DA11 DA18                       DA26 DA29                 5F045 AA08 AB04 BB02 DP05 EH04                       EH14 EK07

Claims (6)

[Claims] 1. A plasma process apparatus comprising a processing chamber, a gas inlet for introducing a material gas into the processing chamber, a plurality of discharge electrodes, and an AC power supply having a plurality of terminals, wherein The terminal includes an output terminal and a terminal having a floating potential other than the output terminal, and the plurality of discharge electrodes include a discharge electrode connected to the output terminal and the output terminal. A discharge electrode that is not connected to the terminal that has the floating potential and that has a ground potential other than the discharge electrode that is connected to, and a discharge electrode that is connected to the output terminal and the floating potential. Plasma processing apparatus capable of switching between a discharge electrode that is not connected to the terminal and that has a ground potential. 2. The output of the AC power supply is a pulse,
The plasma process apparatus according to claim 1, wherein a discharge electrode connected to the output terminal and a discharge electrode not connected to the terminal having the floating potential and having a ground potential are switched for each pulse. . 3. The plasma processing apparatus according to claim 1, wherein the AC power supply has a matching circuit at each of the plurality of terminals. 4. A processing chamber, a gas inlet for introducing a material gas into the processing chamber, a plurality of discharge electrodes, an AC power supply having a plurality of terminals, and a processing substrate holder facing the discharge electrodes. Wherein the plurality of terminals are composed of output terminals and terminals having a floating potential other than the output terminals, and the plurality of discharge electrodes are discharge electrodes connected to the output terminals. A discharge electrode connected to the output terminal during processing, the discharge electrode connected to the output terminal other than the discharge electrode connected to the floating terminal and not connected to the floating potential terminal. In a plasma process apparatus in which an electrode and a discharge electrode that is not connected to the terminal that is at the floating potential and is at a ground potential are switched, the repeating distance of the discharge electrode that is connected to the output terminal is The substrate attached to the substrate holder during processing, a plasma processing apparatus is shorter than the distance between the surface to be processed. 5. The output of the AC power supply is a pulse,
The plasma process apparatus according to claim 4, wherein a discharge electrode connected to the output terminal and a discharge electrode having a ground potential without being connected to the terminal having the floating potential are switched for each pulse. 6. The plasma processing apparatus according to claim 4, wherein the AC power supply has a matching circuit at each of the plurality of terminals.