JP4011315B2 - Plasma process equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma process apparatus used for manufacturing a semiconductor film or an insulating film, and in particular, a plasma chemical vapor deposition apparatus for forming a thin film, a dry etching apparatus suitable as an apparatus using plasma enhanced chemical vapor deposition, or The present invention relates to a plasma process apparatus such as an ashing apparatus.
[0002]
[Prior art]
Conventionally, a plasma process apparatus has been used to manufacture semiconductor films such as amorphous silicon (hereinafter referred to as “a-Si”) and insulating films in the electronics industry. As this plasma process apparatus, there are a plasma chemical vapor deposition apparatus for forming a thin film, a dry etching apparatus, an ashing apparatus, etc. suitable as an apparatus using a plasma enhanced chemical vapor deposition method. Hereinafter, an example of a method for manufacturing a semiconductor device using these devices will be described.
[0003]
A method of forming an electronic device such as an integrated circuit, a liquid crystal display, and an amorphous solar cell by forming a semiconductor film using plasma 11, a so-called plasma-excited chemical vapor deposition (CVD) method, Since it is excellent in simplicity and operability, it is used for manufacturing various electronic devices. As a form of an apparatus (plasma chemical vapor deposition apparatus, hereinafter referred to as “plasma CVD apparatus”) using the method, those shown in the following FIG. 7 and FIG. 8 are common.
[0004]
The plasma CVD apparatus constitutes a closed space using a processing chamber (vacuum vessel) 5, and an electrode 2 composed of two conductive plates placed in parallel at opposite positions that are electrically insulated from each other. A semiconductor film is formed on a film-forming substrate 4 such as silicon or glass attached to one electrode 2 by generating a plasma 11 and flowing a material gas therethrough to decompose and dissociate the gas. .
[0005]
As means for generating the plasma 11 for decomposing the material gas for film formation, electric energy such as high frequency with a frequency of 13.56 MHz is usually used. That is, one conductor plate electrode 2 is set to the ground potential, a voltage is applied to the other opposing electrode 2 to generate an electric field between the two conductor plates, and plasma 11 is generated as a glow discharge phenomenon due to the dielectric breakdown phenomenon. .
[0006]
The electrode to which voltage is applied, that is, the electrode 2 to which electric energy is applied is called a cathode electrode 2a or a discharge electrode, and a large electric field is formed in the vicinity thereof. It promotes gas dissociation and generates radicals. The radical thus generated diffuses as a radical flow 12 to the film formation substrate 4 on the electrode 2 at the ground potential and is deposited on the film formation surface, so that the film grows. The electrode 2 at the ground potential is called an anode electrode 2b.
[0007]
Such a plasma CVD method is widely used in various industries. For example, in the process of manufacturing an active drive type liquid crystal display, a switching element called TFT (Thin Film Transistor) is manufactured, but in the TFT, a gate oxide such as an a-Si film or nitrogen silicon is used as a component of the switching element. The membrane plays an important role. In order for each film to play its role, a technique for efficiently forming a high-quality film is indispensable.
[0008]
The dry etching apparatus or ashing apparatus uses the same plasma 11 as described above to remove the thin film or the resist by changing the gas to be used. Similarly, the TFT of the active drive type liquid crystal display It plays an important role in the manufacturing process. An apparatus for depositing and processing a thin film using the plasma 11 is collectively called a plasma process apparatus.
[0009]
However, plasma processing apparatuses that have been used in the past have limitations. For example, when manufacturing electronic devices such as liquid crystal displays and amorphous solar cells as plasma CVD apparatuses, high-quality films are often formed on the deposition substrate 4. As a result, there has been a problem that the plasma CVD apparatus cannot be stably operated.
[0010]
A very general plasma CVD apparatus has a structure as shown in FIGS. As described above, since the plasma 11 is generated between the cathode electrode 2 a and the anode electrode 2 b, the film formation substrate 4 is always exposed to the plasma 11. Therefore, it is difficult to improve the quality of the film because the film-forming surface is damaged by the impact of ions emitted from the plasma 11.
[0011]
Thus, as a method for forming a high quality film on the film formation substrate 4, for example, there is a technique described in Japanese Patent Application Laid-Open No. 11-144892, which will be described below.
[0012]
In this method, as shown in FIGS. 5 and 6, a film formation substrate 4 provided with a plurality of electrodes 2 having a convex surface is placed at a position away from the electrodes 2, thereby forming a lateral electric field and generating high quality. The film is said to be possible. In this way, by positioning the film formation substrate 4 away from the electrode 2, the film formation substrate 4 is not exposed to the plasma 11, and there is no deterioration in film quality due to ion bombardment on the film formation surface of the thin film. A quality film can be formed.
[0013]
[Problems to be solved by the invention]
However, in this method, there arises a problem that unnecessary discharge occurs at the gas introduction port 6 for ejecting gas to the plasma 11 generation space or at the gas retention portion 7 where the gas is retained before ejection. This is because a leakage electric field is generated at the gas introduction port 6 or the gas retention portion 7 because a voltage is applied between a plurality of electrodes in the vicinity of the gas introduction port 6 or the gas retention portion 7 in order to generate a transverse electric field. Thus, the dielectric breakdown phenomenon is reached.
[0014]
When such a discharge occurs, a high molecular weight substance called powder is generated. According to the knowledge of the authors, an unstable discharge such as a leakage electric field tends to generate powder. If the apparatus is continuously operated in such a state, the powder is accumulated in the gas inlet 6 or the gas retention part 7 and the gas inlet 6 is clogged, or the powder is transferred to the plasma 11 generation space together with the material gas. In other words, it is taken into the film on the substrate as it is.
[0015]
That is, the maintenance of the plasma CVD apparatus is frequently required to remove the powder, or the yield of the manufactured TFT substrate is reduced. That is, this method cannot guarantee stable operation of the plasma CVD apparatus. Further, such unnecessary discharge generates extra power consumption, and the net amount of electric power consumed for film formation is unknown, which hinders the control accuracy of the film thickness. That is, a method for forming a high-quality film on a substrate by stably operating a plasma CVD apparatus has not yet been established.
[0016]
Moreover, although the dry etching apparatus or ashing apparatus conventionally used is used with the apparatus similar to the plasma CVD apparatus shown in FIG. 7 and FIG. 8, this also has a problem. In other words, since the plasma 11 is on the entire surface of the film formation substrate 4, the generation control of radicals and the physical etching operation by ions cannot be controlled separately in the plasma 11. In this case, if the method disclosed in Japanese Patent Laid-Open No. 11-144892, that is, the apparatus having the same structure as the plasma CVD apparatus as shown in FIGS. 5 and 6, the controllability is improved, but the gas is ejected. As in the case of the plasma CVD apparatus, unnecessary discharge is generated in the gas introduction port 6 or in the gas retention part 7 where gas is retained before jetting, as in the case of the plasma CVD apparatus, and unstable apparatus operation. Have the problem of inviting. In short, as a plasma process apparatus, an apparatus capable of performing high-quality film formation with a stable operation has not been established so far.
[0017]
The present invention has been made in view of the above-described problems, and an object thereof is to provide a plasma process apparatus capable of performing high-quality film formation and processing with stable operation.
[0018]
[Means for Solving the Problems]
The plasma processing apparatus of the present invention is surrounded by a plasma processing chamber in which film formation is performed using plasma, a cathode electrode provided in the plasma processing chamber, a cathode electrode and a member electrically connected thereto, A gas retaining part for retaining a gas for introducing a plasma generating gas for generating plasma in the plasma processing chamber, an insulating part provided in contact with the cathode electrode, and facing the cathode electrode through the insulating part The anode electrode, the cathode electrode, and the anode electrode that are provided to communicate with each other, the film formation substrate provided through the space in the plasma processing chamber, and the gas retaining portion and the space communicate with each other only through the cathode electrode. And a gas inlet, and the entire inner wall surface of the gas retaining portion is configured to have substantially the same potential.
[0019]
According to such a structure, it can suppress that powder generate | occur | produces according to the influence of the electric field produced by the electric potential difference of each inner wall surface part of a gas retention part. As a result, high-quality film formation can be performed with stable operation.
A plasma processing apparatus according to another aspect of the present invention includes a plasma processing chamber in which film formation is performed using plasma, a cathode electrode provided in the plasma processing chamber, a cathode electrode, and a member electrically connected thereto. A gas retention part in which a gas for introducing a plasma generating gas for generating plasma is generated in the plasma processing chamber, an insulating part provided in contact with the cathode electrode, and an insulating part The anode electrode provided so as to face the cathode electrode, the cathode electrode and the anode electrode are formed through the space in the plasma processing chamber, and the gas stays through both the cathode electrode and the insulating portion. And a gas introduction port for communicating the portion and the space, and the entire inner wall surface of the gas retention portion is configured to have substantially the same potential.
Even with such a configuration, it is possible to suppress the generation of powder due to the influence of the electric field generated by the potential difference between the inner wall surfaces of the gas retention portion. As a result, high-quality film formation can be performed with stable operation.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the plasma processing apparatus of the present embodiment will be specifically described with reference to the drawings.
[0027]
(Embodiment 1)
The plasma process apparatus of the present embodiment will be described by taking a plasma CVD apparatus as shown in FIGS. 1 and 2 as an example. The plasma process apparatus of the present embodiment uses a mechanical booster pump or a rotary pump for discharging gas attached to the apparatus. As a material gas for generating plasma, SiH ₄ (1000 sccm) and hydrogen (1500 sccm) are used. As shown in FIG. 1, the introduction of the material gas is performed from the gas inlet 6 aligned with the striped cathode electrode 2a. A high frequency power source with a frequency of 13.56 MHz is used to apply electrical energy.
[0028]
As shown in FIG. 1 and FIG. 2, a large number of 5 mm × 5 mm × 1000 m aluminum rods and 5 mm × 10 mm × 1000 mm aluminum rods differing only in height from the aluminum rod are used as electrode portions. It is arranged on an aluminum plate having a thickness of 1100 mm × 1100 mm and a thickness of 3 mm. The aluminum plate and the aluminum bar of 5 mm × 10 mm × 1000 mm are fixed by using bolts so as to be surely in electrical contact. The space between the electrode 2a and the electrode 2b is formed by interpolating alumina, which is an insulator, into respective shapes to form an interelectrode insulating layer 3. When a structure in which the electrode 2a and the electrode 2b are combined and the interelectrode insulating layer 3 is called an electrode substrate, the entire electrode substrate has a size of 1100 mm × 1100 mm × 13 mm.
[0029]
A high frequency voltage is applied to the aluminum plate portion of the electrode substrate, and an aluminum bar of 5 mm × 10 mm × 1000 mm functions as the cathode electrode 2a having a high frequency potential. An aluminum bar of 5 mm × 5 mm × 1000 mm insulated by the cathode electrode 2a and the interelectrode insulating layer 3 functions as the anode electrode 2b having the ground potential. The gas retention portion 7 has a structure in which the aluminum plate of the electrode substrate and other inner walls are all made of metal and are electrically at the same potential.
[0030]
In addition, since each gas inlet 6 is also designed to penetrate one aluminum rod that functions as the cathode electrode 2a, the inner wall has a structure that is at the same electrical potential. Furthermore, the inner walls of the gas inlet 6 and the gas retention part 7 are at the same potential.
[0031]
As the film formation substrate 4, a glass substrate having a thickness of 1.1 mm is installed at a position 15 mm away from the cathode electrode 2a. Although not shown in FIGS. 1 and 2, a heater is attached after the film formation substrate holder 9 holding the film formation substrate in order to heat the film formation substrate 4 (at a film formation substrate temperature of 200 ° C.). ing.
[0032]
When the operation state of the apparatus with the gas pressure of 80 Pa and the high-frequency power of 500 W was examined with respect to the plasma process apparatus of FIG. 1, an amorphous silicon film was formed, and a film formation speed of 5 mm / sec was obtained. I was able to. Further, when the gas inlet 6 and the gas retention part 7 were examined after the operation of the apparatus, the generation of powder was not confirmed.
[0033]
On the other hand, for the purpose of comparison, the same operation test was performed on the apparatus shown in FIGS. The plasma process apparatus of FIGS. 5 and 6 is the same as the plasma process apparatus of FIGS. 1 and 2 except for the following points. The conventional plasma processing apparatus shown in FIG. 5 and FIG. 6 is an alumina plate in which the electrode substrate is constituted by a large number of aluminum rods of 5 mm × 5 mm × 1000 mm, the size is 1100 mm × 1100 mm, and the thickness is 10 mm. Is placed on top. The entire electrode substrate has a size of 1100 mm × 1100 mm × 100 mm. That is, it is almost the same as the structure in which the aluminum plate is removed from the electrode substrate of FIG. Since the upper part of the gas retention part 7 is an alumina surface, it is inevitable that a high-frequency electric field due to a high-frequency voltage applied to the electrode on the upper part will enter.
[0034]
Moreover, since each gas inlet 6 is also designed to penetrate the alumina plate which is the interelectrode insulating layer 3, it has a structure in which a high-frequency electric field exists inside. That is, the inner wall surface of the gas inlet 6 is not at the same potential, and the inner wall surface of the gas retention portion 7 is not at the same potential.
[0035]
When the operation state of the apparatus was examined by setting the gas pressure to 80 Pa and the high frequency power to 500 W with respect to the conventional plasma process apparatus shown in FIGS. 5 and 6, as in the case of the plasma process apparatus shown in FIGS. 1 and 2. A film formation rate of 4.5 liters / second at which the amorphous silicon film was formed was obtained. However, when the gas inlet 6 and the gas retention part 7 were examined after the operation of the plasma process apparatus, a large amount of powder was generated, and the entire inner wall of the gas inlet 6 and the gas retention part 7 turned brown due to powder adhesion. It was. The reason why such powder is generated is as follows.
[0036]
Since the inner wall surface of the gas inlet 6 and the inner wall surface of the gas retention part 7 are not at the same potential, the plasma 11 is generated by the leaking high frequency electric field. As a result, powder was generated. Moreover, the reason why the film forming rate was reduced by 0.5 liter / second was that a part of the introduced high-frequency power was spent on abnormal generation of the plasma 11 at the gas inlet 6 and the gas retention part 7. In addition, the decrease in the deposition rate was not grasped until the deposition substrate was taken out and measured. That is, the operation of the film forming apparatus is unstable, and safe operation of the apparatus cannot be expected.
[0037]
As described above, in the plasma process apparatus according to the present embodiment, since the inner wall of the gas retention part 7 has substantially the same potential, the generation of powder is suppressed, and a stable apparatus operation is possible. Here, for example, even when a part of the inner wall of the gas retaining part 7 is made of a dielectric and the potential of the inner wall is slightly different from that part, that is, the potential of the entire inner wall of the gas retaining part 7 is Even if they are not completely the same, plasma 11 and powder are not generated and no problem occurs. That is, the same effect as the above experimental result can be expected if the entire inner wall surface is substantially at the same potential to the extent that unnecessary discharge does not occur in the gas retention portion 7. The same applies to the inner wall of the gas inlet 6. In addition, when the potential difference between the entire inner wall of the gas inlet 6 and the entire inner wall of the gas retaining portion 7 is large, a discharge occurs between the inner wall surfaces and powder generation occurs. From the result, it can be seen that it is desirable that the inner wall of the gas inlet 6 and the inner wall of the gas retention part 7 are exactly the same or substantially the same so that no discharge occurs.
[0038]
The plasma process apparatus of the above embodiment is an apparatus having a size mainly assuming an apparatus in a TFT process for a liquid crystal display, but the same effect can be exhibited regardless of the size of the apparatus. For example, as a film forming / dry etching / ashing apparatus currently used for a process for manufacturing an integrated circuit on a silicon wafer, an apparatus size of about 12 inches is assumed, but such a relatively small plasma process is assumed. In the apparatus, the same effect can be obtained if the structure is as described above.
[0039]
In addition, materials such as aluminum and alumina, which are electrode substrate materials used in the plasma processing apparatus of the present embodiment, are not limited to these materials. For example, the aluminum used for the electrode substrate and the gas retention portion 6 can be replaced with stainless steel and various metal alloys as long as the conductivity can be maintained, and the alumina used for the electrode substrate can be Teflon (R) or photo. Other insulating materials such as veils can be substituted.
[0040]
Furthermore, although the plasma process apparatus of the present embodiment has been described by taking the plasma CVD apparatus as an example, it is not limited to the plasma CVD apparatus, and thin film processing using the plasma 11 widely, such as a dry etching apparatus or an ashing apparatus. Applicable to the device. For example, when applied to a dry etching apparatus, the gas species for generating plasma may be changed to CF ₄ , SF ₆ , Cl ₂ , HC, BCl ₃ , O ₂ or the like. When used as a dry etching apparatus, a substrate bias electrode is separately attached to the back surface of the film formation substrate 1.
[0041]
In this case, if the structure is as shown in FIGS. 5 and 6, the plasma 11 is generated in the gas retention part 6 and the gas introduction part 7, and therefore the electric power consumed to generate the abnormal plasma 11 can be predicted. As a result, there arises a disadvantage that the power specification ratio of how much is actually used in the dry etching operation is unpredictable. On the other hand, by using the plasma process apparatus shown in FIG. 1, it is possible to perform safe operation in a state controlled as an apparatus without generating plasma 11 at the gas retention part 7 or the gas inlet 6.
[0042]
In the plasma process apparatus of the present embodiment, as described above, the gas introduction port 6 is realized by passing a hole through the first conductor component, and the gas retention part 7 is configured by a combination of the second conductor component. It is effective to combine the first conductor component with the second conductor component, or to integrally form the first component and the second component.
[0043]
(Embodiment 2)
The plasma processing apparatus according to the present embodiment will be described below with reference to FIGS. The operation results of the plasma process apparatus of the present embodiment are shown below. The plasma CVD apparatus shown in FIGS. 3 and 4 is used, and the configuration and conditions are the same as those of the first embodiment except for the contents described below. As shown in the drawing, the electrode substrate is composed of a large number of aluminum rods of 5 mm × 5 mm × 1000 mm, and is arranged on an aluminum plate having a size of 1100 mm × 1100 mm and a thickness of 3 mm.
[0044]
The space between the electrodes 2 is filled with alumina, which is an insulating material, processed into each shape. The entire electrode substrate has a size of 1100 mm × 1100 mm × 13 mm. A high frequency voltage is applied to the aluminum plate portion of the electrode substrate, that is, the entire inner wall of the gas retention portion 6, and an aluminum rod of 5 mm × 5 mm × 1000 mm insulated with alumina is at ground potential. That is, the aluminum plate of the electrode substrate functions as the cathode electrode 2a, and the aluminum rod of 5 mm × 5 mm × 1000 mm functions as the anode electrode 2b. The gas retention portion 7 has a structure in which the aluminum plate of the electrode substrate and other inner walls are all made of metal and are electrically at the same potential.
[0045]
In addition, since each gas inlet 6 is designed to penetrate the alumina plate which is the interelectrode insulating layer 3, strictly speaking, the inner wall does not have the same potential, but the potential of the surrounding components is Since it is symmetric with respect to the gas inlet 6, the inner surface of the gas inlet 6 can be regarded as substantially the same electric potential in the horizontal direction in the figure, so that a discharge hardly occurs. In this case, the high-frequency voltage application portion that is the cathode electrode 2a is not exposed to the discharge space, but the high-frequency electric field is held in the discharge space through the upper inter-electrode insulating layer.
[0046]
When the gas pressure was set to 80 Pa, the high frequency power was set to 65 W, and the operation state of the apparatus was examined with respect to the plasma process apparatus shown in FIGS. 3 and 4, an amorphous silicon film was formed, and the film formation rate was 5 mm / sec. Could get speed. Moreover, when the gas inlet 6 and the gas retention part 7 were investigated after the operation of the plasma process apparatus, the generation of powder was not confirmed.
[0047]
According to the plasma process apparatus of the present embodiment as described above, film formation and thin film processing on the film formation substrate 4 can be performed with stable apparatus performance.
[0048]
In addition, in order to produce an active drive type liquid crystal display, it is necessary to have a TFT portion using an amorphous silicon film or the like, but it is possible to form and process a high quality film with stable device operation in the manufacturing process. Thus, improvement can be achieved in terms of ensuring reproducibility of device fabrication, reducing maintenance time, and improving yield.
[0049]
Further, in the fields other than the liquid crystal display, the same effect can be obtained as an amorphous silicon film forming apparatus which is a light conversion layer of an amorphous silicon solar cell which is also formed by the plasma CVD method.
[0050]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
[0051]
【The invention's effect】
According to the above plasma process apparatus, it is possible to suppress the generation of powder due to the influence of the electric field generated by the potential difference between the inner wall surfaces of the gas retention part, so that high-quality film formation is performed with stable operation. be able to.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a plasma chemical vapor deposition apparatus for forming a thin film according to a first embodiment.
2 is a view showing a cross section of the plasma chemical vapor deposition apparatus for forming a thin film according to Embodiment 1. FIG.
FIG. 3 is a diagram showing a schematic configuration of a plasma chemical vapor deposition apparatus for forming a thin film according to a second embodiment.
4 is a view showing a cross section of a plasma chemical vapor deposition apparatus for forming a thin film according to Embodiment 2. FIG.
FIG. 5 is a diagram showing a schematic configuration of a conventional plasma chemical vapor deposition apparatus for forming a thin film.
FIG. 6 is a cross-sectional view of a conventional plasma chemical vapor deposition apparatus for forming a thin film.
FIG. 7 is a diagram showing a schematic configuration of a conventional plasma chemical vapor deposition apparatus for forming a thin film.
FIG. 8 is a cross-sectional view of a conventional plasma chemical vapor deposition apparatus for forming a thin film.
[Explanation of symbols]
1 Power supply (for applying electrical energy), 2 electrodes, 2a cathode electrode, 2b anode electrode, 3 interelectrode insulating layer, 4 deposition substrate, 5 processing chamber (vacuum container), 6 gas inlet, 7 gas retention part , 8 lead-in terminal, 9 film formation substrate holder, 11 discharge (plasma), 12 radical flow, 13 gas supply unit, 14 gas flow.

Claims (2)

A plasma processing chamber in which a film is formed using plasma ;
A cathode electrode provided in the plasma processing chamber;
A gas retaining portion surrounded by the cathode electrode and a member electrically connected thereto, and in which a gas for introducing a plasma generating gas for generating plasma is retained in the plasma processing chamber ;
An insulating portion provided in contact with the cathode electrode;
An anode electrode provided to face the cathode electrode through the insulating portion;
The cathode electrode and the anode electrode are a film formation substrate provided through a space in the plasma processing chamber,
A gas inlet that passes through only the cathode electrode and communicates the gas retention part and the space ;
A plasma processing apparatus configured so that the entire inner wall surface of the gas retention portion has substantially the same potential. A plasma processing chamber in which a film is formed using plasma;
A cathode electrode provided in the plasma processing chamber;
A gas retention part surrounded by the cathode electrode and a member electrically connected thereto, in which a gas for introducing a plasma generating gas for generating plasma is generated in the plasma processing chamber;
An insulating portion provided in contact with the cathode electrode;
An anode electrode provided to face the cathode electrode through the insulating portion;
The cathode electrode and the anode electrode are a film formation substrate provided through a space in the plasma processing chamber,
A gas inlet that penetrates both the cathode electrode and the insulating part to communicate the gas retaining part and the space;
A plasma processing apparatus configured so that the entire inner wall surface of the gas retention portion has substantially the same potential.

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