JPS63121666A - Device for forming functional deposited film by microwave plasma cvd method - Google Patents

Abstract

PURPOSE:To form a functional deposited film having high quality at a high speed on a conductive substrate having a coaxial circular cylindrical shape by forming a film forming chamber to a cylindrical shape consisting of a conductive material and disposing the above-mentioned substrate into said chamber at the time of forming the above-mentioned film by a microwave plasma CVD method on the substrate. CONSTITUTION:The conductive substrate 6 having the coaxial circular cylindrical shape to be formed thereon with the functional deposited film consisting of amorphous silicon, etc., is disposed into a vacuum vessel 1 having the cylindrical shape and after the inside is evacuated to a vacuum through a discharge pipe 5, the reactive gas such as silane, etc., are introduced and microwaves 4 are introduced through a waveguide port 3 and introducing window 2, then plasma 7 is generated to decompose the silane and to form the deposited amorphous silicon film on the surface of the substrate 6. The chamber for generating the plasma 7 in the vacuum vessel 1 is made into the construction which makes coaxial or semicoaxial resonance with the microwaves, by which the surface of the substrate 6 is enveloped with the uniform plasma and the uniform thin amorphous silicon film is deposited at high speed on the substrate.

Description

Detailed Description of the Invention [Technical Field to which the Invention Pertains] The present invention relates to a film deposited on a substrate, particularly a functional film, particularly a semiconductor device, a photoreceptor device for electrophotography, a line sensor for image input, an imaging device, an optical The present invention relates to an apparatus for forming functional deposited films such as amorphous semiconductor films used in electromotive force devices and the like.

(Description of Prior Art) Conventionally, amorphous silicon has been used as element materials for semiconductor devices, electrophotographic photoreceptor devices, line sensors for image input, imaging devices, photovoltaic devices, and various other electronic devices, optical devices, etc. Specifically, for example, amorphous silicon (hereinafter referred to as r a-51 (H,

) have been proposed, and some of them have been put into practical use.

Then, such a deposited film is deposited using a plasma CVD method, that is,
It is known that it is formed by a method in which a raw material gas is decomposed by direct current, high frequency, or microwave glow discharge, and a thin film is formed on a substrate such as glass, quartz, heat-resistant synthetic resin film, stainless steel, or aluminum. The equipment for this purpose is also available for each f! Proposed.

By the way, recently, Bladder 7 was developed by microwave glow discharge decomposition.
CVD method (hereinafter referred to as 'MW-PCVD method').

) has been attracting attention at the industrial level, and the MW-P
An apparatus for forming a deposited film by the CVD method typically has an apparatus configuration shown in a perspective schematic diagram in FIG.

In FIG. 9, 1 indicates the entire vacuum vessel, 2 is a microwave introduction window made of a dielectric material such as alumina ceramics or quartz glass, 3 is a waveguide, and 4 is a microwave,
5 is an exhaust pipe, 6 is a substrate for film formation, and 7 is a film formation chamber N (plasma generation chamber).

Deposited film formation in such conventional deposited film forming equipment is as follows:
This is done as follows.

That is, the inside of the vacuum container 1 is evacuated via the exhaust pipe 5, and the substrate 6 is heated to a predetermined temperature by a heater (not shown) built in a holding table (not shown) of the substrate.
Hold. Next, for example, in the case of forming an amorphous silicon deposited film, silane gas (SiF4)-hydrogen gas (H2
) etc. into the film forming chamber 7 of the vacuum container 1 in a 1 x 1
Supply while maintaining the degree of vacuum below 0-'Torr.

Next, from a microwave power source (not shown), for example, 2.45
A GH microwave 4 is introduced into the film forming chamber 7 via an isolator, a power monitor, a stub tuner (not shown), a waveguide 3, and a microwave introduction window 2. The film forming chamber 7 has a microwave resonator structure surrounded by a microwave introduction window 2 and a conductive substrate 6 arranged on the circumference, and efficiently converts the introduced microwave energy into plasma. Absorb.

Thus, success! ) The raw material gas introduced into K7 is excited by microwave energy and dissociates, producing neutral radical particles, ion particles, electrons, etc., which react with each other to form a deposited film on the surface of the substrate 6. It is formed.

By the way, in such a method of forming a deposited film using the microwave plasma CVD method, since the plasma formed is an ionized body, it acts as an absorber or a reflector for microwaves that have the property of spatially propagating inside a dielectric material. This plasma density decreases as the degree of vacuum increases, as the mean free path of charged particles becomes longer. Therefore, by increasing the degree of vacuum during plasma formation, the propagation distance of microwaves can be increased.

However, when attempting to form a deposited film mainly composed of neutral radical particles, the lower limit of the degree of vacuum is on the order of 10-3 Torr. Therefore, when attempting to form a deposited film on a long substrate such as an electrophotographic drum, there is a problem in that it is difficult to generate plasma uniformly over the entire length of the substrate. For this reason, in the conventional MW-PCVD apparatus, microwave energy is introduced from two locations at the upper and lower ends of the drum to make the plasma uniform.

In addition, in the MW-PCVD apparatus having the configuration shown in FIG. 9, since the plasma is surrounded by the substrate 6, the generated active species can be effectively deposited on the substrate surface. The disadvantage is that a deposited film is formed only in a part of the area (the area exposed to the plasma).

For this reason, in the conventional tW-PCVtl apparatus, a deposited film is uniformly formed over the entire surface of the substrate by rotating the substrate 6.

However, since the same part of the substrate surface alternately passes through the deposited film formation area and the formation area, the thickness of the film deposited by the time it goes around and returns to the same position is the same as that of the film exposed to the plasma. It cannot be more than half of That is, there was a drawback that the deposition rate was reduced to less than half.

Furthermore, the substrate needs to be rotated many times to reach the film thickness (20 μm or more) required for electrophotographic drums.
There was a problem that the deposited films were stacked. In particular, when a large number of laminated interfaces are formed in the photoelectric conversion layer, they block the flow of electrons, preventing the photoelectric conversion ability from being effectively demonstrated and causing a serious problem in that the performance as an electrophotographic drum cannot be fully achieved. do.

[Purpose of the invention]

An object of the present invention is to overcome the problems in the conventional devices as described above, and to provide an element member for use in semiconductor devices, electrophotographic photoreceptor devices, photovoltaic devices, various other electronic devices, optical devices, etc. An object of the present invention is to provide an apparatus capable of forming a functional deposited film stably and at high speed by the MW-PCVD method.

That is, the main object of the present invention is to uniformly deposit an a-5i:H+X+ film by efficiently utilizing microwave energy in an apparatus for forming a functional deposited film by the MW-PCVD method, and at the same time to deposit the a-5i:H+X+ film. The purpose of the present invention is to provide an optimal device for improving speed.

(Structure of the Invention) The present inventor has conducted extensive research in order to overcome the aforementioned problems with conventional methods and devices and achieve the above-mentioned object of the present invention, and has found that a-5i :H:
X: It has been found that in order to form a film efficiently, it is important to surround the entire surface of the substrate with uniform plasma.

It has been found that the means for generating such uniform plasma requires that the plasma generation chamber has a coaxial coaxial or semi-coaxial resonant structure that can satisfy the coaxial resonant mode.

It was also found that as long as the plasma generation chamber satisfies the coaxial resonance mode, there is a degree of freedom in selecting the method of introducing microwaves into the plasma generation chamber. That is, even if the microwave introduction window is in the TE resonance mode, once the microwave enters the plasma generation chamber, it changes to the coaxial mode, that is, the TEa+resonance mode. therefore,
An electric field is formed in the radial direction of the center conductor, and plasma is generated uniformly in the coaxial circumferential direction. Therefore, it has been found that the deposition rate of the deposited film becomes uniform in the circumferential direction, and a uniform deposited film without laminated interfaces can be formed without reducing the deposition rate. Furthermore, it has been found that the film thickness in the central axis direction can also be made uniform by introducing microwaves from the upper and lower ends of the plasma generation chamber having a coaxial structure.

The present invention was completed based on these findings, and the apparatus for forming a functional deposited film by the microwave plasma CVD method of the present invention has a substrate holding means inside a sealed film forming chamber. , comprising a source gas supply means to the film forming chamber and an exhaust means for the film forming chamber, and a part of the wall of the film forming chamber is covered with microwave i! from a microwave power source. Microwave plasma CVD composed of a microwave transmission window that allows lA
A device for forming a functional deposited film using a coaxial or semi-coaxial resonant method, wherein the film forming chamber is formed of a conductive material into a cylindrical shape, and a conductive coaxial cylinder is arranged inside the film forming chamber. It is characterized by its container structure.

The apparatus of the present invention having the above configuration is a five-speed device for carrying out the deposited film forming method by MW-PCVD ti, and the film forming chamber (plasma generation chamber) has a microwave resonant structure. By reducing the reflection loss of the microwaves generated in the film forming chamber, it is possible to efficiently provide plasma generation energy, and at the same time, by generating a coaxial resonance mode within the film forming chamber, the It is characterized by uniform generation of plasma.

The inventor of the invention also obtained the following findings in the present invention.

That is, by arranging a plurality of metal rods parallel to the central axis between the conductive cylinder that forms the film forming chamber and the conductive coaxial cylinder placed inside it, uniformity of the film thickness in the axial direction can be achieved. It became clear that further improvements could be made.

Furthermore, we found that by placing a coaxial ring in the middle of the film forming chamber to the extent that it does not block the microwaves, it is possible to prevent the energy of the microwaves introduced from above and below from being excessively synergized. Ta.

Another apparatus of the present invention, which was completed based on these findings, is that a metal rod as a phase shifter is installed inside the film forming chamber of the apparatus having the above structure, as a phase shifter, for the purpose of making the plasma density uniform. Appropriately select a structure in which a plurality of microwaves are arranged inside the reaction chamber parallel to the substrate, and a donut-shaped metal plate as a microwave reflecting plate for the purpose of adjusting the amount of microwave input is arranged inside the reaction chamber at right angles to the substrate. The present invention is characterized in that the plasma density distribution in the central axis direction of the substrate, that is, the deposited film formation rate distribution is made uniform.

In the apparatus of the present invention, in order to propagate microwaves inside the film forming chamber during plasma generation, the degree of vacuum inside the film forming chamber at the time of introducing the raw material gas is set to less than I It is desirable to have a plurality of dielectric windows for introducing microwaves into the deposition chamber in consideration of wave reflection and breathing.

Furthermore, since the apparatus of the present invention has a structure in which an exhaust pipe is disposed in a part of the film forming chamber as a microwave resonator, the entrance of the exhaust pipe is such that microwaves do not enter the exhaust pipe. In order to prevent the resonant frequency from changing, it is desirable that a shielding material against microwaves be placed so as not to increase the exhaust resistance.

Hereinafter, the apparatus for forming a functional deposited film by the MW-Pi:VD method of the present invention will be explained in more detail with reference to the embodiments of the drawings, but the present invention is not limited thereto.

Figure N1 is a schematic perspective view schematically showing a typical example of a bag lid for forming a functional deposited film by the MW-PCVD method of the present invention.

In the figure, components of the device having the same functions as those of the conventional device described above (shown in FIG. 9) are indicated by the same symbols as in FIG.

In the figure, 1 is a vacuum-tight vacuum container of the device of the present invention, 2 is a dielectric window for introducing microwaves, 3 is a waveguide connected to a microwave power source (not shown), and 4 is a waveguide section connected to a microwave power source (not shown). It's a microwave. Reference numeral 5 denotes an exhaust pipe connected to an exhaust device (not shown) for evacuating the inside of the reaction vessel, and its opening is covered with a microwave shielding material 8. Reference numeral 6 denotes a base body as a conductive coaxial cylinder, which is arranged so as to share a central axis with the vacuum vessel 1. 7 is a plasma generation chamber. Although the microwave introduction window 2 in the figure is configured to have the TE resonance mode, it is converted to the coaxial resonance mode within the vacuum vessel of the present invention, so it may be configured as the TEo+coaxial resonance mode. .

Further, although not shown in the drawings, the apparatus of the present invention is provided with a gas supply means and a gas discharge port for discharging raw material gas into the vacuum container.

Note that the opening size of the gas discharge port needs to be such as to prevent microwaves from entering.

Furthermore, it is assumed that the substrate 6 is heated and maintained from the inside by heating means (not shown) such as a heater so that the surface temperature is suitable for forming a deposited film.

FIG. 2 is a schematic perspective view showing another embodiment of the present invention, in which components having the same functions as those of the embodiment described above will be described using the same symbols.

Unlike the device of the previous example, which radiated microwaves from both the upper and lower ends in the direction of the central axis, this example device has a structure in which microwaves are radiated from the side of the reaction vessel perpendicular to the central axis. It is characterized by Even with such a microwave radiation method, the inside of the plasma generation chamber 7 is in a coaxial resonance mode, and it is possible to exhibit the same performance as the apparatus of the above embodiment.

Furthermore, in the apparatus of this embodiment, the substrate 6 can be carried out and removed in the middle and 0ζ axis directions, which is advantageous when vacuum conveyance of the substrate is considered.

FIG. 3 is a perspective diagram schematically showing another embodiment of the present invention. In the drawings, the same symbols are used for components having the same functions as those of the apparatus of the embodiment.

The device shown in FIG. 3 is an example in which a metal phase shifter 9 is further arranged in the device shown in FIG. They are evenly spaced. The length of the metal rod 9 is 0.0, where the length of the base is L'.
5 L'<L<1. The thickness is preferably within the range of SL', and the thickness is preferably about 21 to 10 mm.

The apparatus of this embodiment is particularly effective as a supplementary means for cases where microwaves are not transmitted to the center of the substrate (that is, cases where the film formation rate at the center decreases).

FIG. 4 is a schematic perspective view schematically showing still another embodiment of the present invention. In the drawings, the same symbols are used for components having the same functions as those of the apparatus of the embodiment.

The device shown in FIG. 4 is an example in which a metal ring 10 is further arranged in the device shown in FIG. It is fixed and held.

The inner diameter of the ring is in the range D≦D'', where D' is the diameter of the base body 6 and D' is the inner diameter of the vacuum vessel 1, in order to partially transmit the microwave energy. It is preferable that the thickness is about 2 mm.

In this example device, in a high vacuum such as 2 x 1O-3 Torr, the electron density in the plasma decreases, so the transmission distance of the microwave increases, and the plasma density increases due to the interaction of the microwaves at the center of the substrate. On the other hand, it acts to suppress this.

As explained above using the embodiment apparatus shown in FIGS. 1 to 4, the apparatus of the present invention has a plasma generation chamber having a coaxial resonator structure, and the purpose is to cover the surface of the substrate with uniform plasma. Therefore, the microwave radiation means, raw material gas supply means, evacuation means, etc. can be selected as appropriate.

In addition, in the apparatus of this example, the substrate was configured as a conductive coaxial cylinder arranged inside, but the method of arranging the substrate is not limited to this. Good too.

Furthermore, in the apparatus according to the embodiment of the present invention, only one vacuum vessel is illustrated, but in practice, the apparatus may be composed of a large number of vacuum vessels. In this case, the microwave may be branched from one power source. Further, there is no problem even if the raw material gas supply means and the exhaust means are used in common.

In addition, in the embodiment device of the present invention, the conductive cylinder of the coaxial resonator is constituted by the vacuum container 1, but the conductive cylinder or the conductive coaxial cylinder inside the conductive cylinder is If configured with a wave shield member, this can be regarded as one film forming chamber, and a large number of these film forming chambers can be used as one film forming chamber.
The structure may be arranged in two vacuum containers.

(Example) Hereinafter, the formation of a functional deposited film using the apparatus of the example will be specifically explained with reference to an example.

In this example, the apparatus shown in FIG. 1 was used.

First, the inside of the reaction vessel 1 is degassed from the exhaust pipe 5 connected to an exhaust device (not shown), and the pressure inside the reaction vessel is reduced to 1 x 1.
Adjusted to 0'''Torr or less.

Next, a heater (not shown) was energized to heat and maintain the temperature of the substrate 6 at 250°C. There, via a raw material gas supply means (not shown) and a gas discharge port (not shown),
Silane gas 500sec, hydrogen gas 200sec
The system pressure is 2 x 1O
-3Torr, and at the same time, the upper and lower microwave power supplies (not shown) were energized to a frequency of 2.45G.
Microwaves 4 of Hz were simultaneously radiated into the reaction vessel through the waveguide 3 and the dielectric window 2 to generate plasma in the plasma reaction chamber 7 to perform open film formation at a predetermined time. After that, heating of the substrate, gas supply, microwave radiation, etc. are stopped.
After allowing the substrate to cool, it was carried out of the system. The same operation was repeated, replacing the dielectric window 2 with one to which no deposited film was attached, and also replacing the substrate 6 to form the deposited film 10 times in total. Here, in the dielectric window 2, when an amorphous silicon film for electrophotography is deposited, a film with a thickness of 20 μm or more is deposited and acts to prevent microwaves from entering the reaction vessel. , it is necessary to replace the base with a new one every time the base is replaced.

The deposition rate of the deposited film thus formed was 100 people/sec. This was more than three times faster than the average deposition rate of 30 persons/sec of the conventional apparatus. Moreover, the film thickness distribution in the circumferential direction of the substrate surface was uniform even though the substrate was not rotated. Furthermore, the film thickness distribution in the central axis direction was also uniform. From the above results, it has become clear that the electric field intensity distribution in the reaction chamber of the apparatus of the present invention is in the coaxial resonance mode.

Furthermore, as a result of measuring the electrical properties of the deposited film, the S/N ratio of electrical conductivity was 4 digits, compared to the deposited film that was only 3 digits thick with conventional equipment due to layered film formation. It was also clear that there was an improvement.

An amorphous silicon deposited film was formed on the substrate in the same manner as in Example 1 except that the apparatus shown in FIG. 3 was used in this example.

Figure 5 shows four metal rods with a length of 35 cm arranged, silane gas and hydrogen gas used as source gases, and a vacuum degree of 8X.
It shows the film thickness distribution in the substrate axis direction of an amorphous silicon film formed at 1O-3Torr and microwave power of 800ω.

FIG. 6 shows the film thickness distribution when the film was formed under the same conditions except that the four metal rods were not arranged.

As is clear from FIG. 5.6, the uniformity of the film thickness distribution was improved by arranging the metal rods as metal phase vessels.

In this example, an amorphous silicon film was deposited on a substrate in the same manner as in Example 1 except that the apparatus shown in FIG. 4 was used.

Figure 7 shows an amorphous silicon film formed using silane gas and hydrogen gas as raw materials, a vacuum degree of 2 x 10'''3 Torr, and a microwave power of 800 ω, with two metal rings lO attached to the base body positions 15 cm and 25 cm. It shows the film thickness distribution of the film in the direction of the substrate axis.

FIG. 8 shows the film thickness distribution when the film was formed under the same conditions except that the metal ring 10 was not disposed.

As is clear from FIG. 7.8, by arranging the metal ring 10, the film thickness distribution at the center of the substrate could be made uniform.

(Summary of the Effects of the Invention) The apparatus of the present invention has a plasma reaction chamber in which a substrate is arranged as a coaxial or semi-coaxial resonator structure, and by surrounding the substrate with uniform plasma, it is possible to coat the substrate surface in the plane direction and thickness direction. In both cases, a uniform a-5I:H:X film can be deposited at high speed.

[Brief explanation of the drawing]

1 to 4 are perspective diagrams schematically showing an embodiment of the present invention. 5 to 8 are diagrams showing the film thickness distribution in the axial direction of the substrate, where the vertical axis indicates the position in the axial direction of the substrate, and the horizontal glaze indicates the film thickness. FIG. 9 is a schematic perspective view showing a typical example of an apparatus for forming a functional deposited film using the conventional MW-PCVD method. In Figures 1 to 4 and 9, 1...vacuum vessel, 2...microwave introduction window 3...waveguide section, 4...microwave, 5...
... Exhaust pipe, 6 ... Base, 7 ... Plasma generation chamber, 8 ... Microwave shielding material, 9 ...
...metal rod, lO...metal ring patent applicant
Canon Co., Ltd. Figure 1 Figure 3 (2m) 7th factor (μm)
Figure 8

Claims (10)

[Claims] (1) A substrate holding means is provided inside a sealed film forming chamber, a means for supplying raw material gas to the film forming chamber, and an exhaust means for the film forming chamber, and a part of the wall of the film forming chamber is provided. An apparatus for forming a functional deposited film by a microwave plasma CVD method, the part of which is formed of a microwave-transmitting window that allows transmission of microwaves from a microwave power source, the film-forming chamber being formed of a conductive material. Formation of a functional deposited film by a microwave plasma CVD method, characterized in that a conductive columnar member is arranged coaxially with the substrate holding means inside the chamber to form a coaxial or semi-coaxial resonator structure. Device. (2) A microwave plasma CVD method according to claim (1), wherein a microwave transmission window that allows microwave transmission is disposed on both end faces, one end face, or side wall of the conductive film forming chamber. A device for forming functional deposited films. (3) The degree of vacuum in the film forming chamber is 1×10^-^2 Tor
An apparatus for forming a functional deposited film by the microwave plasma CVD method according to claim (1), wherein the degree of vacuum is less than or equal to r. (4) A plurality of metal rods are arranged in a space surrounded by the conductive cylinder and the conductive coaxial cylinder, parallel to the coaxial cylinder, and on a concentric circumference with the coaxial cylinder. An apparatus for forming a functional deposited film using a microwave plasma CVD method as described in item 1), item (2), or item (3). (5) Claims (1) and (2) wherein a plurality of metal rings concentric with the coaxial cylinder are arranged in a space surrounded by the conductive cylinder and the conductive coaxial cylinder. An apparatus for forming a functional deposited film using a microwave plasma CVD method according to item 1, item 3, or item 4. (6) The film-forming chamber has exhaust ports provided at a plurality of locations, and the exhaust ports are blocked by a shielding material that blocks microwaves to the extent that the exhaust is not obstructed. ), (2), (3), (4), or (5), an apparatus for forming a functional deposited film using a microwave plasma CVD method. (7) Claim (1), wherein the film forming chamber has a gas supply port provided at a plurality of locations, and the opening size of the gas supply port is smaller than or equal to a size that blocks microwaves; No. (
An apparatus for forming a functional deposited film using a microwave plasma CVD method according to item 2), item (3), item (4), item (5), or item (6). (8) A substrate for forming a functional deposited film is disposed on either or both of the inner wall surface of the conductive cylinder and the outer wall surface of the conductive coaxial cylinder. Section 2), Section (3), Section (4), Section (5), Section (
An apparatus for forming a functional deposited film using the microwave plasma CVD method described in item 6) or item (7). (9) Claims (1) and (2), wherein the conductive cylinder and the conductive coaxial cylinder are formed of a microwave shielding member that does not block exhaust gas.
Formation of a deposited film by the microwave plasma CVD method described in item (3), item (4), item (5), item (6), item (7), or item (8). Device. (10) Claims (1), (2), and (1) in which a coaxial waveguide converter is used as the microwave transmission window.
Section 3), Section (4), Section (5), Section (6), Section (7)
), (8), or (9), an apparatus for forming a functional deposited film using a microwave plasma CVD method.