JP2652292B2 - Plasma processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive column type plasma processing apparatus having a novel container or substrate support (susceptor) structure.

[0002]

2. Description of the Related Art A plasma processing method is a method in which a specific substance is applied with energy such as electromagnetic waves to form a plasma to form radicals having strong activity. The radicals are brought into contact with a substrate to form a film on the substrate, or a material on the surface of the substrate. Means a method for performing plasma processing such as etching and ashing, and a plasma processing apparatus refers to all apparatuses for performing this processing. Such a plasma processing apparatus includes a plasma processing chamber, which is a vacuum vessel provided with a source gas introduction unit and an exhaust unit for plasma generation, and an electromagnetic wave for converting the source gas introduced into the plasma processing chamber into plasma. The apparatus includes an energy supply unit, a substrate to be plasma-processed and a support unit for the substrate, and a heating unit for heating the substrate as necessary.

[0003] Such plasma processing often depends on the activity of radicals, and the degree of plasma processing on a substrate to be processed greatly changes depending on the state of plasma discharge for generating the radicals and the density distribution of the generated radicals. . In order to perform a uniform plasma treatment over a large area, it is necessary to select a state of plasma discharge that generates radicals uniformly and in a large amount over a large area. 13.56 MHz high frequency, microwave, direct current or low frequency electromagnetic wave energy is used as the electromagnetic wave energy for converting the raw material gas into plasma, and plasma discharge by high frequency is often used.

There are two types of such plasma discharges: an inductive coupling type and a capacitive coupling type. The inductive coupling type is a so-called non-polar discharge, and the capacitive coupling type is a well-known parallel plate electrode type. . FIG. 2 is a schematic view of a plasma CVD apparatus as an example of the parallel plate electrode type plasma processing apparatus. Thus, a pair of parallel plate electrodes (100) and (101) are provided in the reaction chamber (106), and each is connected to the high frequency power supply (102). The substrate to be processed (103) is usually mounted on one electrode, and the substrate is heated by a heating means (104) such as a heater.

After the reaction gas is introduced into the reaction chamber through the gas inlet (105), it is decomposed and activated by the high-frequency power supplied to the electrodes, and a film is formed on the substrate (103). In order to perform uniform plasma processing (film formation) on the substrate, it is necessary to realize uniform plasma discharge. FIG.
As described above, the electrode on which the substrate is placed may be rotated to compensate for the uniformity, but there is a drawback that the apparatus becomes complicated and the size becomes large. In general, during plasma processing, the substrate to be processed is usually disposed on a cathode (cathode) or an anode (anode) of a parallel plate electrode or in a cathode dark area or an anode dark area generated in the vicinity thereof. . Therefore, the surface to be processed cannot be made larger than the dimensions of the electrode.

Incidentally, in the manufacturing technology of semiconductor elements and electronic equipment parts, technologies such as plasma CVD and plasma etching have been widely put into practical use, and many such devices for mass production have been proposed. In recent years, the diameter of a substrate wafer of a semiconductor element and the size of the substrate have been remarkably increased. Particularly, in the case of an active matrix type liquid crystal electro-optical device in which a thin film transistor is formed as a switching element of the liquid crystal electro-optical device, the size thereof is remarkably increased, and a semiconductor film for the thin film transistor is formed on a substrate having a size of 15 to 20 inches diagonally. It is necessary to form or perform an etching process. At the same time, it is desired to reduce the processing time for the purpose of reducing the manufacturing cost, and an apparatus capable of improving the throughput of the processing apparatus and processing a large number of substrates has been required.

[0007]

In order to meet such a demand, the size of the plasma processing apparatus has been increased. For example, as one example, the size of the electrode of the apparatus as shown in FIG. Is performed. That is, in the case of the apparatus as shown in FIG. 2, since the substrate is placed directly on the electrodes, the largest area of the electrodes is the simplest method for improving the processing capacity. In the case of such a parallel plate type plasma processing apparatus,
Increasing the electrode dimensions directly leads to an increase in the dimensions of the apparatus, which has been a problem for users who want to process large substrates with an apparatus having a small floor space.

In addition, as the electrode area increases, the density of the plasma in contact with the surface of the substrate to be processed becomes non-uniform (discharge state is non-uniform), so that there is a problem that uniform plasma processing cannot be performed. I was As one means for solving such a problem, a method has been proposed in which a plurality of parallel plate electrode pairs are provided in a reaction chamber and a substrate to be processed is provided on the electrodes. However, there is a problem that the structure of the apparatus becomes complicated. . In addition, even with this method, the nonuniformity of the plasma discharge due to the enlargement of the area remains, and there has been a situation where uniform plasma processing cannot be performed.

As another method, a method has been proposed in which a plurality of substrates are placed at a fixed interval between a pair of substrates and plasma treatment is performed. In other words, the basic idea of this method is to utilize a positive column region of plasma glow discharge and perform a plasma treatment by arranging a plurality of substrates to be processed in the positive column region. A plasma CVD method using this positive column is disclosed in Japanese Unexamined Patent Application Publication No.
59834, 59-59835. This method is shown in FIG. As shown in the figure, a pair of electrodes (10
0) A plurality of substrates (103) are placed between (101) by a substrate susceptor (110). The susceptor is provided as an integral part or an integral part of the container (113), and the substrate is handled by taking the container in and out of the reaction chamber. For simplification, only the vicinity of the plasma discharge region is shown in FIG. In this method, electrode shields (111) and (112) are provided around the electrodes in order to effectively use the positive column of plasma, and a reaction region is limited by the electrode shield and the outer peripheral wall of the container (113). The plasma is confined so that no discharge occurs outside.

In the case of such a system, in order to improve the plasma processing capacity and reduce the volume occupied by the apparatus, it is conceivable to reduce the gap between the substrates and the gap between the substrate susceptor and the electrodes as much as possible. . However, in the case of the conventional method, there is a problem that the plasma discharge becomes unstable, and the discharge disappears or becomes non-uniform, and uniform plasma processing cannot be performed by narrowing these intervals.

[0011]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and provides a novel plasma processing apparatus capable of processing a large substrate to be processed in a short processing time and capable of performing uniform plasma processing. It proposes a simple structure.
Further, instead of performing the plasma processing area on the surface of the limited electrode dark area, the plasma processing is performed in a space called a positive column area, and a plurality of substrates to be processed are arranged in this space.
This plasma space is divided into a plurality of individual plasma processing spaces, the state of the plasma in each of the individual processing spaces is made uniform, and the plasma state in each individual space is not different so that a large amount of plasma is generated. This enables processing and processing of a large-area substrate.

A schematic diagram of FIG. 1 will be described below as an example of the present invention, and the description will be made with reference to this diagram. FIG. 1 is a schematic diagram showing only a portion around a plasma discharge region in a reaction chamber. The discharge region of the plasma processing apparatus according to the present invention is limited to a space (4) surrounded by the electrode shields (1) and (2) and the outer peripheral wall of the container (3). In order to prevent the discharge (parasitic discharge) with the portion (2), it is installed in the immediate vicinity and its potential is installed. The substrate susceptor (5) is in a state where its surface potential is floating (floating). By doing so, the susceptor (5) or the substrate (6)
The atmosphere in which the plasma is in contact with the plasma in the discharge space individually divided into six (in FIG. 1, divided into six) can basically realize a floating state except for a pair of electrodes, thereby achieving a uniform discharge. That is, it is possible to realize uniform plasma processing.

As an example of the means for bringing the surface potential of the susceptor (5) into a floating state, as shown in FIG. 4 (B), a schematic sectional view of a material used for the container or the susceptor is used. (When the substrate susceptor (5) is made of the same material, it can be formed by forming or coating a material that is insulative with respect to the power for plasma discharge to be used over the entire outer periphery thereof. A container and a substrate susceptor are prepared by using a metal material such as aluminum nickel or an alloy material thereof as a base material (20), and an insulating film such as an oxide film or a nitride film of the metal material or an insulating film of another material is formed on the surface thereof. (19) is formed by a technique such as plasma oxidation, plasma nitridation, anodic oxidation, and plasma spraying. The potential of the susceptor surface can provide containers or susceptor to float.

In addition, instead of using such an insulating material to form a container and a susceptor using a material provided on the surface thereof, a container and a substrate susceptor are manufactured using an ordinary metal material. As a structure, a floating susceptor can be realized by electrically insulating the outer container and the container including the inner susceptor. FIG. 4A shows a schematic diagram of this structure. This figure is a schematic view of the container viewed from above, and as shown in the figure, the outer container (1)
Inside 5), an inner container (16) including a susceptor (18) is provided at regular intervals via an insulating material (17). In order to install the container in a predetermined place in the reaction vessel, only the outer container is supported and installed in the reaction chamber. This allows the inner container and susceptor to float.

As described above, if the portion exposed to the plasma atmosphere, such as the susceptor for supporting the substrate and the peripheral wall of the container, has an insulating surface, even if the distance between the holding of the substrate and the distance between the electrode and the susceptor are reduced. It is possible to perform stable discharge and uniform plasma processing. That is, in the case of the conventional positive column type plasma processing apparatus as shown in FIG. 3, when the distance between the substrate holding and the distance between the electrode and the susceptor becomes narrow, a current flows between the electrode (100) and the electrode (101). , Susceptor and substrate surface.
This is shown by the dashed line (115) in FIG. Therefore, even when the plasma discharge is observed at the start of the discharge and the plasma discharge is stopped in a state where there is no reflection with respect to the incident power,
No reflected power is observed. The present invention realizes stable, uniform, large-area plasma discharge by eliminating such a current path.

Therefore, by making the container wall or the susceptor in contact with the plasma discharge atmosphere floating or using an insulating surface, the path of the electric power supplied for generating such plasma is cut off, and stable discharge is realized. Things. Hereinafter, the present invention will be described with reference to examples.

[0017]

Embodiment 1 This embodiment shows an example in which the structure of the discharge region shown in FIG. 1 is applied to a positive column type plasma CVD apparatus. FIG. 5 shows a schematic diagram thereof. As shown in the figure, a substrate carry-in chamber (21), a first reaction chamber (22), a second reaction chamber (23), and a substrate take-out chamber (24) respectively have gate valves (26), (27) and (28). They are connected continuously across them. Further, gate valves (25) and (29) are provided in the substrate loading chamber (21) and the substrate unloading chamber (24), respectively, and are shielded from the outside. In addition, individual room (22)
(23) (24) and (25) have independent evacuation systems (3
0), (31), (32), and (33) are connected, and each chamber can be evacuated and maintained at a predetermined pressure and atmosphere. This exhaust system has a conductance valve (34), a stop valve (35) (36) for adjusting the exhaust flow rate, a turbo molecular pump (37) capable of oil-free vacuum exhaust, and a water for low vacuum exhaust as basic components. Includes a sealed pump (38). In addition, an exhaust bypass system and a plurality of exhaust systems can be installed as necessary.

Further, each of the chambers is provided with an independent gas supply system (40) (41) (42) (43).
A plurality of supply systems are provided to the reaction chambers (22) and (23) so as to supply a reaction atmosphere gas and other gases. These gas supply systems basically include a flow controller (44) and a stop valve (45). In addition, in this embodiment, a halogen lamp heating means is provided in the substrate loading chamber (21) and the reaction chambers (22) and (23) for heating the substrate because of the plasma CVD apparatus. The substrate heating means is installed at a position that cannot be described in the cross section of FIG. 5, that is, at the front and back surfaces of the plane of FIG. 5, from which light is irradiated in a direction parallel to the substrate surface to heat the substrate. It has become. The installation position of the heating means can be provided on the surface on which the upper and lower electrodes are provided in addition to this position, and can be changed as necessary. Also, the heating means can be changed to various modes such as a resistance heating method and an induction heating method other than the halogen lamp method.

The susceptor structure around the discharge region shown in FIG. 1 was applied to the plasma CVD apparatus having such a structure. In this embodiment, the substrate is 600 mm × 800 mm × 1.1 mm
10 glass substrates whose surfaces were polished were placed with a susceptor (5) interposed therebetween. FIG. 6 shows the appearance of the susceptor (5) and the container (3) including the susceptor. As described above, in the present embodiment, the substrate (6) installed on the susceptor has a structure in which all other surfaces are surrounded by the outer peripheral wall of the container except for a pair of outer peripheral surfaces of the container.

In this embodiment, in order to make the potential of the susceptor and the substrate surface floating, the material of the container and the susceptor is aluminum metal.
Produced. Thereafter, the entire outer surface of the container and the susceptor is subjected to anodizing treatment, and the entire outer surface is provided with a thickness of 1 to 1
5 μm In this example, a 5 μm alumina film was formed uniformly. That is, the cross sections of all the containers and the members of the susceptor have a structure as shown in FIG. 4 (B). In the present embodiment, since the substrate is heated, the container and the susceptor thermally expand due to the heat, and the container and the susceptor thermally contract when the substrate is taken out after the processing. At this time, the outer insulating film may be cracked or cracked due to a difference in the degree of warping between the outer insulating film and the inner metal material. Therefore, in the case of the present embodiment, once the outer insulating film is formed thinner than a predetermined thickness, heat treatment is performed, and then the insulating film is formed again, thereby suppressing the occurrence of cracks and cracks in the outer insulating film. Was.

The minimum distance between the discharge electrodes (1) and (2) and the container (3) or the susceptor (5) is 3 to
The distance was 10 mm, and in this embodiment, 6 mm. If the distance is 10 mm or more, the volume of the device is increased, so that the interval is set as small as possible. If too narrow, plasma CVD
Since the substrate is heated for the apparatus, there is a problem that the container, the susceptor, the electrode, etc. are thermally expanded and come into contact with each other. Therefore, a distance of about 3 mm is required depending on the dimensions of the apparatus.

In the case of the plasma CVD apparatus of this embodiment, the positional relationship between the container (3) and the susceptor (5) and the electrodes (7) and (8) and the electrode shields (1) and (2) in the reaction chamber is shown in FIG. The relationship is as follows. That is, FIG.
(A) is a schematic diagram showing the positional relationship as viewed from the same direction as in FIGS. 1 and 5, but the electrode shields (1) and (2) and the container (3) face each other at the ends in the left and right direction. There is a part (13) (14) that is extended
５5 mm In this embodiment, it is 3 mm. By doing so, the container (3) can move in the left-right direction of the drawing. FIG. 7B is a schematic view of a cross section of the plane of FIGS. 1 and 5 in a direction normal to the plane. In this direction, a portion (13) of which only the ends of the electrode shields (1) and (2) are extended in the vertical direction overlaps with the outer peripheral wall of the container (3) at a distance of 2 to 5 mm.

Due to such a relationship between the container (3) and the electrode shields (1) and (2), the container can be moved, and plasma discharge can be caused by the electrode shields (1) and (2) and the outer periphery of the container (3). It becomes possible to confine only in the area surrounded by the wall. Further, as shown in FIG. 7B, there is a feature that the volume of the device can be reduced by extending the end of the electrode shield in the vertical direction.

The substrate (6) installed by the container (3) in the substrate loading room (21) is processed in the processing room (21).
The chamber is evacuated to an ultimate vacuum of 2 × 10 ^-7 Toor, and then heated to 300 degrees by a heating means. Thereafter, under substantially the same pressure conditions as in the first reaction chamber (22),
Open the gate valve (26) and place the container in the first reaction chamber (2).
After moving to 2), the gate valve (26) is closed. In this reaction chamber, after forming the first thin film under predetermined conditions, the chamber is evacuated again, the gate valve (27) is opened under the same pressure as in the second reaction chamber, and the container is placed in the second reaction chamber. Move to the chamber and form a second thin film. Thereafter, the chamber is evacuated again, the gate valve (28) is opened under the same pressure conditions as the substrate unloading chamber (24), and the container is moved. Thereafter, the substrate is left in this chamber, or a refrigerant or a cooling gas is introduced into the extraction chamber (24) until the substrate temperature is lowered, the substrate temperature is lowered, and then the extraction chamber (24) is returned to the atmospheric pressure. Open valve (29) and remove. With such a flow,
Thin film formation is performed on many substrates. In the case of such a device configuration, the present invention can be applied to formation of a gate insulating film and a semiconductor layer of a thin film transistor and manufacture of electronic elements such as a solar cell and a diode.

With such a configuration, the plasma discharge confined in the plasma reaction region is caused by the pair of electrodes (7) and (8), and the discharge power is input on the substrate surface and the susceptor surface. , Does not pass, and almost all the input power is supplied to the gas in the space, thereby achieving a stable discharge and a uniform plasma discharge. Therefore, in the apparatus according to the present embodiment, the film formed on the substrate has good uniformity of film thickness on the substrate surface.
A film thickness uniformity of ± 5% could be achieved within a substrate size of 00 × 800 mm, and a film thickness uniformity of ± 10% could be achieved within the same lot (10 in this embodiment).

There are various methods for making the potential of the susceptor surface floating as in this embodiment. The simplest means is feasible if the container and the susceptor or the susceptor are made of an insulating material, for example, quartz or the like.However, in order to make the substrate-sized container or the susceptor of the present embodiment made of quartz, it is technically necessary. Impossible or very expensive and not practical. Furthermore, since it is very brittle and easily broken when made of quartz, it is difficult to move and install a container by a robot when performing unmanned work in the future, which hinders the line design of automation.

Further, when a metal material is used for a container or a container and a susceptor as in the present embodiment, particularly when the substrate is heated by plasma CVD or the like, the heat uniformity is very good, and the substrate and the container are heated. This is characterized in that the substrate temperature distribution due to the difference in the substrate position is hardly observed. Therefore, as a means for heating the substrate, even if the entire substrate is not heated after uniforming the temperature distribution of the heating means as in the conventional resistance heating or the like, one end or both end directions of the substrate are used as in the present embodiment. Even when heating was performed, uniform heating could be achieved over the entire substrate, and in addition, the heating rate was high, and the time for plasma processing could be shortened.

[Embodiment 2] In this embodiment, the structure of the discharge region is almost the same as that of Embodiment 1, but a container having a double outer frame structure as shown in FIG. Adopted. In other words, using a nickel material,
The container (15) for producing the container (15) and the susceptor (16) has a double frame structure, and an outer frame (18) is provided on the outside thereof via an insulating material (17). The container is supported in the reaction chamber by the outer frame (18). This allows the inner susceptor to be electrically floating. With such a structure, the potential on the susceptor surface can realize a floating state, and such a floating state can be realized using a metal material.
An inexpensive, simple structure and a robust container could be obtained.

As the insulating material (17), an insulator, a heat-resistant rubber or an organic resin can be used, but other materials can be used as long as they do not degas in the vacuum reactor and have heat resistance. . For comparison, the results of measuring the uniformity of the film thickness when a silicon film was formed under the film forming conditions described in Table 1 for the device configuration of the present embodiment and the case of the conventional device configuration (FIG. 3) are shown. It is shown in FIG. Here, in the case of the conventional apparatus configuration, the susceptor is made of a metal material and is connected to the ground as a potential, and the stability of discharge cannot be ensured. A metal susceptor which is 60% of that of the example was used.

[0030]

[Table 1]

[0031]

[Table 2]

As described above, in the case of the present embodiment, the number of substrates to be processed at one time can be increased as compared with the related art.
In addition, since a stable and uniform plasma discharge can be realized, there is a feature that variation in the degree of processing between substrates can be reduced.

[0033]

According to the structure of the present invention, it is possible to realize a plasma processing apparatus capable of processing a large amount of substrates in a very compact apparatus area and volume. Furthermore, the degree of plasma processing in a large-area substrate can be made uniform, and when applied to the production of thin film transistors as switching elements for liquid crystal displays, the production yield of products can be made extremely high. In addition, since the container is inexpensive and robust, there is a secondary effect that it is not necessary to deal with problems such as container breakage when designing an automation line by a robot.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the vicinity of a discharge region of a plasma processing apparatus according to the present invention.

FIG. 2 is a schematic diagram of a conventional plasma processing apparatus.

FIG. 3 is a schematic view of a discharge region of a conventional positive column type plasma processing apparatus.

FIG. 4 is a schematic view of the container and susceptor of the present invention.

FIG. 5 is a schematic diagram showing the configuration of the present invention when a multi-chamber type plasma CVD apparatus is used.

FIG. 6 shows an example of the container and susceptor structure of the present invention.

FIG. 7 is a schematic sectional view showing the relationship between the container and the electrode shield of the present invention.

Continuation of the front page (72) Inventor Shunpei Yamazaki 398 Hase, Atsugi-shi, Kanagawa Prefecture Inspector, Semiconductor Energy Laboratory Co., Ltd. Kazuo Seki (56) References JP-A-2-246111 (JP, A)

Claims (4)

(57) [Claims] At least one reaction chamber provided with a means capable of evacuating to a reduced pressure state, gas supply means capable of supplying a gas to the reaction chamber, and a pair of electrodes installed in the reaction chamber and generating a plasma discharge And the pair of electrodes face each other.
A plasma processing apparatus comprising: an electrode shield covering the electrodes except for a region to be processed; and a container for installing a plurality of substrates to be processed supported by a susceptor between the pair of electrodes, An inner side, a plasma processing apparatus having a container for placing a number of substrates to be processed in a potential floating state on the surface of the susceptor, wherein the inner side of the container and the surface of the susceptor are
The electrode seal is held in a floating state in terms of potential.
Ground of the electrode shield, the electrode shield and the container
And the prescribed area prescribed by the susceptor
Generated by the power supplied from the pair of electrodes.
Plasma characterized by confining generated plasma
Processing equipment. 2. The plasma processing apparatus according to claim 1, wherein the susceptor or the container is made of a material made of a metal or alloy and covered with an insulator. Plasma processing apparatus. 3. The plasma processing apparatus according to claim 1, wherein the container has a double structure, and a susceptor supporting a substrate and one of the outer frame of the double structure are electrically connected to each other. A plasma processing apparatus characterized by being electrically insulated. 4. At least one reaction chamber provided with a means capable of evacuating to a reduced pressure state, a gas supply means capable of supplying a gas to the reaction chamber, and a pair of electrodes installed in the reaction chamber and generating a plasma discharge And the pair of electrodes face each other.
A plasma processing apparatus having an electrode shield covering the electrodes except for a region to be processed, and a container for installing a plurality of substrates to be processed supported by a susceptor between the pair of electrodes.
The container and the susceptor are metal
Or made of an alloy, the inside of the container and the support
The surface of the scepter is coated with an insulator, and the container,
Holds the susceptor electrically floating
Then, the potential of the electrode shield is grounded, and the electrode shield is grounded.
Field, the container, and the susceptor
Is supplied from the pair of electrodes in a defined area.
Patent that plasma confinement that occur by that power
Plasma processing equipment.