JPH03191068A - Microwave plasma device - Google Patents

Abstract

PURPOSE:To obtain a long-sized region for irradiation with plasma and to allow the inline treatment of a large-area substrate by opening one end of plural coaxial tubes arrayed in the longitudinal direction of a microwave waveguide into a vacuum vessel disposed with a substrate to be worked. CONSTITUTION:Microwave electric power 1 for discharge is transmitted in the square waveguide 2 and is branched to 4 pieces of the coaxial tubes 3 arrayed and connected in the longitudinal direction of the waveguide 2. This electric power is controlled in quantity by a variable shorting plate 7 and is transmitted toward the vacuum vessel 6. Gaseous raw materials for film formation supplied into the vessel 6 are ionized to generate the plasma 10 in the vessel. The plasma 10 generated from the respective coaxial tubes 3 is circular in section and spreads and overlaps on each other; therefore, the long-sized plasma long in the direction where the coaxial tubes are arrayed is formed as a whole. The long-sized substrate 12 of the large area for film formation is disposed under this plasma and is transported in the direction perpendicular to the direction where the coaxial tubes 3 are arrayed. The continuous film formation is thereby executed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a film forming device, an etching device, an ion irradiation device, and other surface treatment devices that utilize microwave plasma for thin film processing. This relates to a microwave plasma generator for in-line processing of a large-area processed substrate.

BACKGROUND OF THE INVENTION Conventional thin film processing apparatuses using microwave plasma have been filed by the inventors of the present invention, such as Japanese Patent Laid-Open No. 155535/1983. These methods utilize an electron cyclotron resonance phenomenon caused by microwave power and a magnetic field, and can generate high-density plasma in a high vacuum such as a 10-' Toll platform, but they all rely on a single plasma generation source.

Problems to be Solved by the Invention In recent years, in the field of thin film processing, there has been a desire to develop an apparatus capable of processing large-area substrates, as seen in the demand for larger screens for liquid crystal displays, for example. In order to industrially process large-area substrates, it is necessary to achieve in-line processing, and for this purpose, it is necessary to generate plasma with a long cross section.

However, in the conventional technique described above, a cylindrical resonator is used in the discharge chamber, so the cross-sectional shape of the plasma that can be generated is circular. Moreover, since the inner diameter of the discharge chamber is limited by the resonance conditions, the size of the plasma is also limited. Therefore, the conventional microwave plasma apparatus described above has a problem in that it is not possible to process a large-area substrate in-line.

Means for Solving the Problems The present invention for solving the above problems includes a rectangular waveguide for transmitting microwave power for discharge, and a plurality of rectangular waveguides arranged in a longitudinal direction of the rectangular waveguide. A device having a coaxial tube, one end of the plurality of coaxial tubes opening toward the inside of a vacuum container, and a substrate to be processed to be transported while maintaining a constant distance from the plurality of coaxial tubes in the vacuum container. It is. In the present invention, the interval between the plurality of coaxial tubes arranged in the length direction of the rectangular waveguide is an integral multiple of 1/2 of the tube wavelength of the microwave power transmitted in the rectangular waveguide, and the rectangular waveguide A reflected power amount adjustment means for microwave power is provided for each of the plurality of coaxial tubes arranged in a row, and as the reflected power amount adjustment means for the microwave power,
It is possible to adopt a movable short-circuit plate, or one in which the length of the inner conductor of each of the plurality of coaxial tubes protruding into the vacuum or the length of protruding into the rectangular waveguide is variable.

Furthermore, the conveyance direction of the substrate can be diagonal to the direction in which the plurality of coaxial tubes are arranged, or by extending and folding a rectangular waveguide in which a plurality of coaxial tubes are arranged in a row, the direction of conveyance of the substrate to be processed can be A plurality of rows of coaxial tubes are formed perpendicular to the column, and the coaxial tubes are installed between the plurality of rows while maintaining the installation interval of the coaxial tubes at an integral multiple of 1/2 of the tube wavelength of the rectangular waveguide. It is also possible to arrange them so that they are coaxial with respect to the transport direction axis of the substrate to be processed and do not overlap.

Operation With the above configuration, the microwave power transmitted through the rectangular waveguide is branched and supplied to a plurality of coaxial tubes arranged in line at the wavelength within the rectangular waveguide, and then enters the vacuum vessel. As is well known, inside a vacuum vessel, in addition to electric discharge between the inner and outer conductors of the coaxial tube due to microwave power, electron cyclotron resonance is generated by a magnetic field generated by a magnetic field generating means provided on the outer periphery of the part of the coaxial tube inserted into the vacuum vessel. The processing gas supplied into the vacuum vessel is ionized to generate plasma. The generated plasma is radiated into the vacuum vessel using the inner conductor as an antenna, but the cross-sectional shape of the plasma is the same as that of a coaxial tube, for example, a plasma with a circular cross section, but multiple rows of coaxial tubes are installed. Therefore, at a position away from the coaxial tube, the plasma generated from each coaxial tube overlaps with each other due to the spread of the plasma, making it possible to obtain plasma irradiation with a long cross section suitable for in-line processing as a whole. Therefore, if the substrate to be processed is kept at a constant height and transported to a position where plasma irradiation of a long cross section can be obtained, a large area of the substrate to be processed can be processed.

In addition to the above configuration, if the installation interval of the plurality of coaxial tubes is configured to be an integral multiple of 1/2 of the tube wavelength of the microwave transmitted through the rectangular waveguide, the microwave power can be reached at the highest point of electric field strength. Since the signal is efficiently transmitted to each coaxial tube, an efficient device can be achieved.

In addition, in order to correct the influence on growth caused by uneven microwave power distributed to each coaxial tube, it is possible to correct the influence on growth by moving the position of the movable shorting plate provided on each coaxial tube, or by moving the inner conductor and placing it in a vacuum. By adjusting the protrusion length or the protrusion length into the rectangular waveguide, the amount of microwave power supplied into the vacuum container is adjusted and made uniform.

In addition, to correct the variation in processing amount in the direction in which the coaxial tubes are arranged due to non-uniform plasma flow density between the center and periphery of the coaxial tubes, it is necessary to change the conveyance direction of the substrate to be processed relative to the direction in which the coaxial tubes are arranged. By placing the coaxial tubes in an oblique direction, it is possible to obtain a condition in which the installation interval of the coaxial tubes is reduced, or by providing multiple rows of coaxial tubes perpendicular to the direction of the conveyance axis of the processed substrate, the installation of the coaxial tubes becomes easier. A state in which the spacing is made smaller is obtained, and uniformity of plasma irradiation on a long cross section is improved.

Embodiment A first embodiment of the present invention will be described with reference to FIG.

FIG. 1 is a schematic configuration diagram of an embodiment in which the present invention is applied to an amorphous silicon thin film deposition apparatus, and FIG.
-A' sectional view. In FIG. 1, microwave power 1 for discharging is supplied from a microwave oscillator (not shown), transmitted through a rectangular waveguide 2, and connected to four coaxial It is branched into pipe 3. Rectangular waveguide 2
There are parts in the length direction of the rectangular waveguide 2 where the microwave electric field becomes stronger periodically. The interval is 1/1/1 of the wavelength of the microwave transmitted in the rectangular waveguide 2, that is, the inner wavelength λ.
It is 2. When connecting the coaxial tube 3 to the rectangular waveguide 2, the microwave power 1 is efficiently transmitted to the coaxial tube 3 by connecting it to a portion where the microwave electric field is strong. Therefore,
The respective coaxial tubes 3 are arranged at intervals of 172 times, which is the tube wavelength λ.

Each coaxial tube 3 is composed of an outer conductor 4 and an inner conductor 5, one end of which opens into a vacuum container 6, and a movable shorting plate 7 attached to the other end. This movable shorting plate 7 is for adjusting the microwave power reflected from the coaxial tube 3, or in other words, for adjusting the amount of microwave power branched to each coaxial tube. Further, a microwave transmission window 9 made of alumina is provided in the coaxial tube 3 in the middle to seal a vacuum and transmit microwave power.

Silane gas, which is a film forming raw material, is supplied to the vacuum vessel 6 through a discharge gas supply port 8 . The rectangular waveguide 2 branches into each coaxial tube 3, and microwave power whose amount is adjusted by a movable shorting plate 7 is transmitted toward the vacuum container 6. A permanent magnet 11 is arranged around the outer conductor 4 to cause electron cyclotron resonance, and this magnetic field and microwave power cause the vacuum part of the coaxial tube 3 and the vacuum container 6 to
Inside, silane gas is ionized and plasma IO is generated. The portion of the inner conductor 5 protruding into the vacuum vessel 6 acts as an antenna and radiates the transmitted microwaves into the vacuum vessel 6, so that plasma 10 is simultaneously radiated into the vacuum vessel 6. The plasma 10 generated within each coaxial tube 3 has a circular cross section. For example, the cross-sectional shape of the plasma taken along the line BB' in FIG. 1 is an individual circle as shown in FIG. 3(a). However, at a position away from the coaxial tube 3 as in the c-c' cross section, the plasma generated from each coaxial tube 3 spreads and overlaps with each other, so as shown in FIG. 2(b),
As a whole, the plasma becomes elongated in the direction in which the coaxial tubes are arranged, so that a thin film of amorphous silicon is deposited on the deposition target substrate 12 placed below this plasma. If the film-forming substrate 12 is a long substrate with a large area as shown in FIG. 2, if it is transported in the direction of the arrow perpendicular to the direction in which the coaxial tubes are arranged,
Amorphous silicon can be continuously deposited.

In this embodiment, an example in which four coaxial tubes 3 are connected to a rectangular waveguide 2 has been described, but the number of coaxial tubes may be adjusted to the size of the required substrate, and the length of the substrate 12 The vacuum container 6 is free to hold up to the maximum capacity.

It should be noted that if the ratio of the micro-power transmitted to each coaxial tube 3 is inappropriate, the thickness and modification of the thin film formed on the film-forming substrate 12 will be non-uniform. each coaxial tube 3
Adjustment means for adjusting the power transmitted to the microphone r is essential and difficult. Such adjustment means include means for moving the setting position of the movable short circuit Fi7 in the direction of the axis of the coaxial tube 3σ as shown in FIG.
The length of the portion 5' of the inner conductor 5 that protrudes into the vacuum vessel 6 may be changed, or the length of the portion 5 that protrudes into the rectangular waveguide 2.
It is also possible to change the length of ``.

Next, second, third and fourth embodiments of the present invention will be explained. FIG. 5 and FIG. 6 are drawings relating to the second and third embodiments of the present invention, respectively, and only show a cross-sectional view corresponding to FIG. 2 of the eleventh embodiment. These examples are:
The purpose of this embodiment is to make the distribution of the film thickness formed on the substrate more uniform in the first embodiment.

In the first embodiment described above, the plasma flow is strong directly below each coaxial tube 3, and the film thickness is slightly thicker than that directly below between the coaxial tubes 3, where the plasma flow is somewhat weaker. This film thickness distribution is emphasized and illustrated in Figure 7 (
a).

In order to reduce this non-uniformity in the film thickness distribution, it can be solved by reducing the installation interval of the coaxial tubes 3, but as mentioned above, the installation interval of the coaxial tubes 3 is regulated by the tube wavelength of the rectangular waveguide 2. Therefore, the following solutions are taken in the second and third embodiments.

First, in the second embodiment, as shown in FIG. 5, the direction in which the substrate to be processed 12 is transported is at an arbitrary angle with respect to the direction in which the coaxial tubes 3 are arranged. In this case, the distance between the coaxial tubes 3 is 172 times the tube wavelength λ as in the first embodiment, but by adopting such a conveyance direction, the substrate to be processed 1
The installation interval W of the coaxial tubes 3 when viewed from the conveyance direction of 2 is:
Since the same effect can be obtained as if the installation interval of the coaxial tubes 3 were made smaller than λ/2, the non-uniformity in the distribution of the film thickness can be reduced as shown in FIG. 7(b).

Next, in the third embodiment, as shown in FIG. 6, if the rectangular waveguide 2 in which coaxial tubes 3 are arranged in rows is extended to add a row of folded coaxial tubes 3, two rows of coaxial tubes 3 are formed. Since the rows of coaxial tubes 3 will be arranged overlappingly in the conveyance direction of the processed substrate, the installation interval of each coaxial tube 3 will be set to 1/2 of the tube wavelength of the rectangular waveguide 2.
When the second row of coaxial tubes 3 are arranged in the middle of the row spacing of the first row of coaxial tubes 3 so as not to overlap on the same axis with respect to the conveyance axis direction of the substrate to be processed 12 while maintaining an integral multiple of coaxial tube 3
Even if the installation interval of the rectangular waveguide 2 is 1/2 of the inner wavelength λ of the rectangular waveguide 2, the interval of the coaxial tubes 3 viewed from the direction of the conveyance axis of the substrate 12 to be processed is equal to the inner wavelength λ of the rectangular waveguide 12. The thickness can be reduced to 1/4, and the non-uniformity of the film thickness distribution can be further reduced as shown in FIG. 7(C).

Next, a fourth embodiment of the present invention will be described with reference to FIG. This example is an example in which the present invention is used in a film forming apparatus for amorphous silicon thin film, as in the previous examples, and FIG. 8 is a schematic configuration diagram, and FIG.
' is a cross-sectional view of the line. In the previous embodiments, the vacuum part of the coaxial tube was used as the discharge chamber, but in this fourth embodiment, a rectangular discharge chamber 13 with a permanent magnet 11 arranged around it is provided, and a microwave transmission window 9 is provided. Coaxial tube 3 and discharge chamber 1
3, and an inner conductor 5 protrudes into the discharge chamber 13. This protruding portion of the inner conductor 5 acts as an antenna and radiates the transmitted microwave power into the discharge chamber 13. Therefore, substantially uniform plasma 10 can be generated within the rectangular discharge chamber 13, and uniform plasma with a rectangular cross section suitable for in-line processing can be generated.

In the embodiments described above, the present invention is applied to an amorphous silicon thin film forming apparatus, but it may of course be used in other thin film forming apparatuses, and may also be used in etching apparatuses, ion irradiation apparatuses, and other devices. Needless to say, it can be used in surface treatment equipment.

Effects of the Invention According to the present invention, it is possible to obtain a plasma irradiation area with a long cross-sectional shape, and since the substrate to be processed is transported through this plasma irradiation area, it is possible to process a large-area substrate. When performing plasma irradiation processing, it is possible to widen the plasma irradiation area by arranging multiple coaxial tubes to match the width, and to set the transport distance to match the length direction. Plasma irradiation processing of the substrate can be performed in-line.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram of the first embodiment of the present invention, Fig. 2 is a sectional view taken along the line A-A' in Fig. 1, Fig. 3 is an explanatory diagram of the shape of plasma, and Fig. 4 is a micro 5 is an explanatory diagram of the second embodiment of the present invention, FIG. 6 is an explanatory diagram of the third embodiment of the present invention, and FIG. 7 is an explanatory diagram of the method of adjusting the wave power. FIG. 8 is a schematic configuration diagram of the fourth embodiment of the present invention, and FIG. 9 is a cross-sectional view taken along line DD' in FIG. 8. be. Microwave power rectangular waveguide coaxial tube vacuum container movable short circuit plate microwave transmission window plasma deposition substrate

Claims (7)

[Claims] (1) It has a rectangular waveguide for transmitting microwave power for discharge, and a plurality of coaxial tubes arranged in a longitudinal direction of the rectangular waveguide, and one end of the plurality of coaxial tubes is evacuated. 1. A microwave plasma apparatus, characterized in that the vacuum container has an opening toward the inside of the container, and a substrate to be processed is placed in the vacuum container to be transported while maintaining a constant distance from the openings of the plurality of coaxial tubes. (2) The installation interval of the plurality of coaxial tubes arranged in the length direction of the rectangular waveguide is an integral multiple of 1/2 of the tube wavelength of the microwave transmitted inside the rectangular waveguide. Microwave plasma equipment. (3) The microwave plasma apparatus according to claim 1, further comprising a means for adjusting the amount of reflected microwave power for each of the plurality of coaxial tubes arranged in a row in the rectangular waveguide. (4) The microwave plasma apparatus according to claim 3, wherein the means for adjusting the amount of reflected power of the microwave power is a movable short circuit plate. (5) The microwave plasma apparatus according to claim 3, wherein the means for adjusting the amount of reflected microwave power varies the length of the inner conductor protruding into the vacuum or into the rectangular waveguide. (6) The microwave plasma apparatus according to claim 1, wherein the direction of conveyance of the substrate to be processed is oblique to the direction in which the plurality of coaxial tubes are arranged. (7) A rectangular waveguide with multiple coaxial tubes arranged in a row is extended and folded back to form a section where multiple rows of coaxial tubes are arranged perpendicular to the direction of the conveyance axis of the processed substrate, and the coaxial tubes are installed. The microwave plasma apparatus according to claim 1, wherein the coaxial tubes are arranged so that the positions of the coaxial tubes between the plurality of rows do not overlap in the direction of the conveyance axis of the substrate to be processed, while maintaining the spacing at an integral multiple of 1/2 of the tube wavelength of the rectangular waveguide. .