JP2784784B2 - Method and apparatus for forming functional deposited film by microwave plasma CVD - Google Patents

Description

Description: TECHNICAL FIELD The present invention is useful for functionally deposited films, particularly semiconductor devices, electrophotographic photoreceptor devices, image input line sensors, imaging devices, photovoltaic devices, etc. TECHNICAL FIELD The present invention relates to an improved method for forming a deposited film by a microwave plasma CVD method for a highly crystalline or non-single crystalline functional deposited film and a deposited film forming apparatus.

[Description of Prior Art]

Conventionally, semiconductor devices, photoreceptor devices for electrophotography,
As an element member used for an image input line sensor, an imaging device, a photovoltaic device, other various electronic elements, optical elements, etc., amorphous silicon, for example, amorphous silicon compensated with hydrogen or / and halogen (eg, fluorine, chlorine, etc.) A non-single crystalline deposited film such as [A-Si (H, X)] or a crystalline deposited film such as a diamond thin film has been proposed, and some of them have been put to practical use.

Such a deposited film is decomposed by a plasma CVD method, that is, a source gas is decomposed by a glow discharge using a direct current, a high frequency, or a microwave, and deposited on a substrate such as glass, quartz, a heat-resistant synthetic resin film, stainless steel, or aluminum. It is known to be formed by a method of forming a hologram, and various apparatuses have been proposed.

Especially, plasma using microwave glow discharge decomposition in recent years
The CVD method, that is, the microwave plasma CVD method has attracted industrial attention.

The microwave plasma CVD method has the advantages of a higher deposition rate and higher source gas utilization efficiency than other methods. Microwave plasma CV taking advantage of these advantages
One example of the D technique is described in JP-A-60-186849. The technology described in this publication is an outline in which a base is arranged so as to surround a means for introducing microwave energy so as to form an internal chamber (that is, a discharge space), thereby improving the utilization efficiency of a source gas. It is. Japanese Patent Application Laid-Open No. 61-283116 discloses an improved microwave technology for manufacturing semiconductor members. That is, this publication discloses that an electrode is provided in a plasma space as a plasma potential control, and a desired voltage is applied to the electrode to perform film deposition while controlling ion bombardment on the deposited film to improve the characteristics of the deposited film. It discloses techniques for improving.

Further, Japanese Patent Application Laid-Open No. 63-241178 discloses another technique for improving the characteristics of a deposited film. That is, the publication discloses that a plurality of substrates are provided so as to surround a discharge space in which plasma is generated, and a voltage is applied to at least one substrate so that an electric field is generated between these substrates to control ion bombardment on a deposited film. To disclose the technology.

These conventional techniques have made it possible to produce a relatively thick photoconductive material at a relatively high deposition rate and source gas utilization efficiency. In the case of manufacturing a cylindrical electrophotographic photosensitive member, for example, the conventional method for forming a deposited film improved in this manner is the same as that shown in FIG. 4 (A) and FIG. 4 (B). FIG. 4 (B) is a schematic cross-sectional view.
(A) Schematic cross-sectional view of the apparatus shown in the figure) is performed as follows through the apparatus shown in FIG.

That is, to describe the apparatus shown in FIGS. 4A and 4B, reference numeral 401 denotes a film forming chamber (reaction vessel);
The chamber has a structure capable of maintaining vacuum tightness. Also,
Reference numeral 402 denotes a microwave introducing dielectric window formed of a material capable of efficiently transmitting microwave power into the reaction vessel and maintaining the inside of the reaction vessel in a vacuum-tight manner, such as quartz glass or alumina ceramics. is there. Reference numeral 403 denotes a microwave power transmission unit formed of a waveguide and connected to a microwave power supply (not shown) via a stub tuner (not shown) and an isolator (not shown). The dielectric window 402 is hermetically sealed to the waveguide 403 wall. An exhaust pipe 404 has one end opening into the reaction vessel 401 and the other end communicating with an exhaust device (not shown). Reference numeral 406 denotes a discharge space formed by being surrounded by the plurality of cylindrical substrates 405.
Note that each of the cylindrical substrates is provided on a cylindrical holder containing a heater 407, and each holder can be appropriately rotated by a driving means (rotary motor) 410.

FIG. 5 is a block diagram showing an example of a circuit of the DC power supply 411 in the conventional device shown in FIG. 4 (A), and comprises a rectifier, a smoothing device, and a power monitor.

The deposition film formation by the conventional deposition film forming method using such an apparatus is performed as follows. First, the inside of the reaction vessel 401 is evacuated by a vacuum pump (not shown) through an exhaust pipe 404, and the pressure in the reactor, that is, the internal pressure is reduced to 1 × 1.
Adjust to less than 0 ^-7 Torr. Next, the heater 407 heats and maintains all the cylindrical substrates (405) at a temperature suitable for film deposition. In the case where an amorphous silicon deposition film is formed, for example, through a gas introduction means provided behind the cylindrical substrate (not shown), the source gas is supplied with a source gas such as silane gas or hydrogen gas into the reaction vessel 401. To be introduced. At the same time, a microwave having a frequency of 500 MHz or more, preferably 2.45 GHz, is generated by a microwave power supply (not shown), and the microwave is generated in the reaction vessel 401 through the waveguide 403 and the dielectric window 402. To be introduced. Further, a DC voltage is applied between the electrode 412 provided in the discharge space 406 and the cylindrical substrate 405. Thus, in the discharge space 406 formed by being surrounded by the plurality of cylindrical substrates (405), the raw material gas is excited and dissociated by the energy of the microwave, and furthermore, becomes constantly cylindrical by the electric field with the cylindrical substrates. While receiving the ion bombardment on the substrate, a deposited film is formed on the surface of all the cylindrical substrates (405). At this time, the deposited film is formed on the entire surface of each cylindrical substrate by rotating all the cylindrical substrates (405) around the apparent central axis in the reaction vessel in the generatrix direction of the substrates.

According to such a conventional method for forming a deposited film, it is possible to obtain a deposited film having practical characteristics and uniformity at a certain deposition rate. If the inside of the reaction vessel is strictly cleaned, it is possible to obtain a deposited film with few defects.
However, in such a conventional method of forming a deposited film, particularly in a region where a deposition rate is high, a relatively thick deposited film having a large area such as an electrophotographic photosensitive member is required. It is said that considerable skill is required to constantly and stably obtain a deposited film that satisfies the requirements of various electrical characteristics and has few defects causing image defects and the like with a high yield (high yield). There's a problem.

That is, when a desired deposited film is formed at a high speed on a large-area substrate such as an electrophotographic photosensitive member, strict control of the plasma potential is necessary. The operation of applying a voltage to a part of the surrounding cylindrical substrate is an important matter. However, when an electric field is applied to the discharge space as described above, the number of defects in the deposited film, which causes image defects and the like, often rapidly increases depending on the voltage applied to the electrodes or a part of the cylindrical substrate. For this reason, it is difficult to obtain a deposited film having good electrical characteristics and few defects even in a large area constantly at a high speed and a high yield by the conventional deposited film forming method by the microwave plasma CVD method.

6 (A) and 6 (B) show an apparatus for performing another conventional method for forming a deposited film. FIG. 4 (A) and FIG.
FIG. 6 (A) is an apparatus of the type in which a voltage is applied to an electrode provided in a discharge space surrounded by a plurality of cylindrical substrates to control a plasma potential. In the apparatus shown in FIG. 6 (B), a plurality of cylindrical substrates are provided so as to surround a discharge space where plasma is generated, and a voltage is applied to at least one substrate so that an electric field is generated between these substrates. The apparatus controls the ion bombardment of the deposited film.

Also in such an apparatus, a power supply (611) for controlling the plasma potential is usually used which has a circuit as shown in FIG.

However, even in such a method of forming a deposited film through the apparatus shown in FIGS. 6A and 6B, an electrophotographic photosensitive member that requires a relatively large deposited film with a large area is required. In the case of manufacturing such as, a deposited film having uniform film quality, satisfying the requirements of optical and electrical characteristics, and having few defects causing image defects and the like is constantly and stably provided with a high yield (high yield). )
In order to obtain it, considerable skill is still required.

[Object of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to overcome the above-mentioned problems in the conventional method for forming a deposited film, and to provide a semiconductor device, a photoconductor device for electrophotography, a line sensor for image input, an imaging device, a photovoltaic device, and various other electronic devices. Microwave plasma-enhanced functional deposition films with excellent properties useful for element members used for elements, optical elements, etc.
It is an object of the present invention to provide an improved method and apparatus for forming a deposited film that can be formed stably at a high yield and at a high deposition rate.

It is a further object of the present invention to provide a non-monocrystalline deposited film such as an amorphous silicon deposited film and a monocrystalline deposited film such as a diamond deposited film, which can form a film having excellent characteristics and few defects. It is an object of the present invention to provide an improved method and apparatus for forming a deposited film by a microwave plasma CVD method.

[Structure and effect of the invention]

In the method for forming a deposited film according to the present invention, a plurality of substrates are arranged in a reaction vessel that can be substantially sealed so as to surround a discharge space, and a reactant contributing to film formation derived from a source gas in the discharge space. Forming a deposited film on the surface of the substrate by forming a discharge plasma including: forming an electric field between the substrate and at least one substrate other than the substrate on at least one of the substrates. Thus, an AC voltage having a frequency of 500 Hz or more and 2 MHz or less is applied.

Further, the deposited film forming apparatus of the present invention is suitable for performing the above-described deposited film forming method of the present invention.
In a reaction vessel that can be substantially sealed, a plurality of substrates are arranged so as to surround the discharge space, and in the discharge space, discharge plasma containing a reactant that contributes to film formation derived from a source gas is formed. An apparatus for forming a deposited film on the surface of the substrate, wherein an AC power supply for generating an AC voltage having a frequency of 500 Hz or more and 2 MHz or less is provided on at least one of the substrates so that an electric field is formed between the substrates. It is characterized by being electrically connected.

The method and apparatus for forming a deposited film according to the present invention having the above-described configuration overcome the above-mentioned problems in the conventional method and apparatus for forming a deposited film.

The present invention has been accomplished by the inventors of the present invention to achieve the above-described object of the present invention, and has obtained the findings described below. is there.

In the microwave plasma CVD method, when a deposited film is formed at a high speed on a large-area base such as an electrophotographic photosensitive drum, a plasma potential is controlled on an electrode provided in a discharge space or a part of the base. It is important to apply a voltage for the purpose. This is because such a microwave plasma CVD method has a high deposition rate and is not sufficient at the basic temperature alone.To compensate for the energy required for desorption of excess hydrogen atoms and rearrangement of silicon atoms, an electric field This is because it is essential to accelerate the ions in the discharge space and collide with the substrate to locally anneal the deposited film. At this time, the voltage applied to the electrode or a part of the substrate contributes to the improvement of the characteristics of the deposited film on the opposing substrate only when a component of the positive voltage is included.

However, the present inventors have found that when a DC electric field is applied to the discharge space as described above, the defects of the deposited film rapidly increase depending on the voltage. That is, when the cross sections of these defects were observed with a microscope, it was observed that abnormal growth of the film occurred in the middle of the deposited film with foreign matter having a size of several microns to several tens of microns as a nucleus. When the DC voltage applied to an electrode or a part of a substrate is increased in order to improve the electrical characteristics of the deposited film, the number of minute foreign substances that cause defects in the deposited film rapidly increases. There was found. The mechanism of this phenomenon is that not only are the ions accelerated by the electric field and collide with the substrate, but also small fragments of the deposited film peeled off from the reaction vessel walls and the substrate are charged up by the plasma and accelerated by the electric field as in the case of the ions. It was considered that the particles adhered to the substrate.

Based on such knowledge, the inventors of the present invention have formed various films to achieve both the improvement of the characteristics by the aforementioned ions and the suppression of the fragments of the charged film deposited on the substrate surface by the action of the electric field. As a result of the examination under the conditions, a voltage is applied to a part of the plurality of substrates, and the resulting electric field is an AC electric field having a frequency that the ions can follow, but the charged fragments cannot follow. Is achieved.

According to the study of the present inventors, it is estimated that such an action of the AC frequency is as follows. That is, it is in the sheath region of the plasma that the ions are actually accelerated by the electric field. Also, the sheath region is depleted of ions.

Therefore, if the time required for ions of mass (m) and charge amount (q) to pass through the sheath region (distance d) under an electric field (E = V / d) is (t), then d = (qE / 2m) × t ² = (q / 2m) × (V / d) × t ² , and for ions to reach the electrode (substrate) under the frequency (F), F ≦ 1 / t, ie, F ≦ (qV / 2md ² ) ^1/2 , and there is an upper limit of the frequency.

On the other hand, the same can be considered for the fragments of the deposited film. In order that the fragments do not reach the substrate, the mass (M) and the charge amount (Q) of the fragments are expressed as follows. The frequency (F) is expressed as F ≧ (QV / 2Md ² ) ^1/2 .

When the charge amount (Q) is constant, the frequency (F) increases as the mass (M) of the fragments decreases. In order for the mass (M) of the fragments to be of a size that does not hinder the growth of the defect in practice, a certain frequency or higher is required, and there is a lower limit of the frequency.

The present inventors have studied this point by repeating experiments, and have reached the above conclusion. In other words, an AC electric field having a frequency of 2 MHz or less, more preferably 500 kHz or less is required for improving the characteristics, and 500 Hz or more for reducing the defects of the deposited film. 2kH
It turned out that an alternating electric field of a frequency of z or more was necessary.

Further, in addition to these facts, setting the frequency to 500 Hz or more means that the base is arranged so as to surround the discharge space shown in FIG. 1 and the base is rotated so that the surface of the base passes through the discharge space at a constant period. It has also been found that when a deposited film forming apparatus having a structure to be used is used, there is an effect of preventing the occurrence of characteristic unevenness of the deposited film depending on the position on the substrate. That is, in the deposited film forming apparatus shown in FIG. 1, the surface of the substrate on which the deposited film is deposited alternately passes through a discharge space and a space without discharge due to the rotation of the substrate. At this time, it has been found that if the frequency of the alternating current applied to a part of the substrate is low, the effect of improving the deposited film due to the electric field varies depending on the position on the substrate, and the characteristics appear uneven.

Also, at this time, the rotation speed of the base is 0.1 rpm to 50
It is also found that the rpm is appropriate, and that the AC frequency must be 500 Hz or more in order to surely eliminate the characteristic unevenness in this range.

The present invention has been completed based on the above-described facts, and in the present invention, the base itself also serves as an electrode for controlling ions for improving characteristics without providing another electrode in the discharge space. The main feature is the configuration described above.
As a result, the conventional technique described above causes a problem that the electrode is actively provided in the discharge space, a deposited film is deposited on the electrode, and the utilization efficiency of the raw material gas is reduced due to the problem. This solves the problem that the film deposited on the electrode is peeled off and the number of defects increases in the deposited film on the substrate. In the present invention, since the base itself is used as an electrode without providing a specific electrode as in the prior art, the so-called electrode surface area can be made sufficiently large and the current density can be reduced. Therefore, it is possible to prevent the abnormal discharge as seen in the related art.

The details of the deposited film forming method and the deposited film forming apparatus of the present invention will be described in detail with reference to the drawings.

FIGS. 1 (A), 1 (B), 2 and 3 are explanatory views for explaining a deposited film forming method and a deposited film forming apparatus according to the present invention. In FIGS. 1A and 1B, reference numeral 101 denotes a film forming chamber (reaction vessel), which has a structure capable of maintaining vacuum tightness. Reference numeral 102 denotes a microwave introduction dielectric window formed of a material capable of efficiently transmitting microwave power into the reaction vessel and keeping the inside of the reaction vessel airtight, for example, quartz glass, alumina ceramics, or the like. It is. Reference numeral 103 denotes a microwave power transmission unit which is formed of a waveguide, and includes a stub tuner (not shown),
It is connected to a microwave power supply (not shown) via an isolator (not shown). Dielectric window 102 is waveguide 1
03 Airtightly sealed on the wall. An exhaust pipe 104 has one end opened into the reaction vessel 101 and the other end connected to an exhaust device (not shown). 106 is a plurality of cylindrical substrates (105-1 to 10-1)
5-6) shows a discharge space formed by being surrounded by 5-6).
The power supply units 111 to 113 are AC power supplies for applying an AC voltage having a frequency of 500 Hz or more and 2 MHz or less to at least one of the bases 105-1 to 105-6. Has a basic circuit consisting of The power supply unit is electrically separated from the reaction vessel 101 wall,
Further, it is electrically connected to at least one of the bases 105-1 to 105-6.

Further, the film introducing gas introducing means is not shown, but the means is, as in the above-mentioned known apparatus, a substrate.
Means for introducing a source gas for film formation from the back of 105-1 to 105-6 toward the discharge space 106 may be used. Alternatively, each substrate in which the substrates 105-1 to 105-6 are arranged and each substrate A gas discharge pipe having a plurality of holes for discharging gas toward the discharge space in a gap between the substrate and the substrate may be provided in parallel with and perpendicular to the substrate, thereby introducing a source gas for film formation.

When at least one of the substrates 105-1 to 105-6 is electrically separated from the wall of the reaction vessel 101 and electrically connected to the AC power supply 111, the rotating shaft electrically connected to the substrate 105 FIG. 2 shows an example of a part where the 109 is electrically separated from the wall of the reaction vessel 101 and is electrically connected to the AC power supply units 111 to 113. In the figure, 201 indicates a part of the reaction vessel. 209 is a rotation shaft made of a conductive material. The inside of the rotating shaft 209 has a double pipe structure, and cooling water is introduced and circulated from cooling water introducing means 220 electrically separated from the reaction vessel 201 by an electric insulating means 221. The rotating shaft 209 is introduced from outside the reaction vessel 201 to the inside of the reaction vessel by vacuum sealing means 213 made of a magnetic fluid. Rotating shaft 209
Is fixed to the vacuum sealing means 213 by fixing means 214 so as not to move in the vertical direction. The vacuum sealing means 213 is connected to the reaction vessel wall by an O-ring and an insulator 215 such that the vacuum tightness of the reaction vessel 201 is maintained and the rotating shaft 209 is electrically separated from the reaction vessel.
The rotation shaft 209 can be rotated at a predetermined rotation speed by a rotational motion transmitting means 216 that has been subjected to electrical insulation processing such as using a ceramic sprocket. Axis of rotation
The voltage is applied to the brush 209 by the brush 217 which is always in electrical contact even when the rotating shaft 209 rotates. Brush 2
17 is fixed to an insulator 218, and is electrically connected to an AC power supply (not shown) by a coaxial cable 219.

FIG. 3 is a block diagram showing the AC power supply units 111 to 113 in FIG. 1A in more detail. The AC voltage having a predetermined frequency oscillated by the oscillator is amplified by an amplifier and passes through a band-pass filter. In the present invention, since the frequency of the AC voltage applied to the substrate greatly affects the quality of the deposited film and the occurrence of defects, it is important to include these bandpass filters that cut off frequency components other than the predetermined frequency. That is. Subsequently, after matching of the impedance with the reaction vessel is performed by a matching circuit, an AC voltage is applied to the substrate.

In the present invention, if an electric field is applied between the substrates, one or more substrates to which an AC voltage is applied may be used. However, applying the same voltage to all the substrates at this time is not included in the configuration of the present invention because a sufficient electric field is not generated between any of the substrates and the plasma potential cannot be controlled.

A preferred method of applying a voltage in the present invention is to apply an AC voltage to an arbitrary one (for example, the base 105-1) in an apparatus in which the number of bases surrounding the discharge space is six as shown in FIG. A configuration in which the other five (105-2 to 105-6) are electrically grounded can be exemplified as a preferable configuration.

In addition, every other (for example, 105-1, 105-3, 105-
5) Apply an AC voltage to the other substrates (105-2, 105-
4, 105-6) is grounded electrically, the electric field in the discharge space becomes uniform, and the area of the substrate to which voltage is applied is equal to the area of the substrate to which voltage is not applied. This is a more preferable configuration because the uniformity of the electrical characteristics between the deposited films above is good and abnormal discharge hardly occurs.

In the present invention, if an electric field is generated between the substrates, any configuration other than the above-described configuration for applying a voltage to an arbitrary number of substrates is possible in order to achieve the object of the present invention.

In the case where the number of substrates is eight or more, as in the case of six, good results can be obtained by the above-described configuration. In the case where the number of substrates is an odd number, any suitable voltage application method can be adopted, although a structure for applying a voltage every other substrate cannot be adopted.

The AC waveform used in the present invention may be any of a sine wave and a rectangular wave. Further, a DC voltage may be superimposed in a range that maintains the effects of the present invention such as improvement of characteristics and reduction of defects.

In the present invention, as a material of a window for introducing a microwave into a film forming furnace, alumina (Al ₂ O ₃ ), aluminum nitride (Al
N), boron nitride (BN), silicon nitride (SiN), silicon carbide (SiC), silicon oxide (SiO ₂ ), beryllium oxide (BeO),
A material with low microwave loss such as Teflon or polystyrene is selectively used.

In the present invention, the effect is exhibited in any range of the pressure in the discharge space, but particularly good results can be obtained with good reproducibility when the pressure is 100 mTorr or less, preferably 50 mTorr or less.

As the base material, for example, stainless steel, Al, Cr, Mo, A
Metals such as u, In, Nb, Te, V, Ti, Pt, Pd, Fe, alloys of these, or synthetic resins such as polycarbonate whose surface is conductively treated,
Glass, ceramics, paper and the like can be appropriately selected and used.

The substrate may have any shape, but is preferably a cylindrical shape. The size of the substrate is not particularly limited, but is practically preferably from 20 mm to 500 mm in diameter and from 10 mm to 1000 mm in length. The distance between the substrates is preferably 1 mm or more and 50 mm or less. The number of substrates may be any number as long as a discharge space can be formed, but is preferably 3 or more, and more preferably 4 or more.

The method of heating the substrate in the present invention may be any heating element having a vacuum specification, and more specifically, an electric resistance heating element such as a wound heater of a sheath heater, a plate heater, or a ceramic heater, a halogen lamp, or an infrared lamp. And the like, and a heating element using a heat exchange means using a liquid, a gas, or the like as a heating medium. As the surface material of the heating means, metals such as stainless steel, nickel, aluminum, and copper, ceramics, heat-resistant polymer resins, and the like can be used.

In addition, other means such as providing a container dedicated to heating other than the reaction container, heating, and then transporting the substrate into the reaction container in a vacuum can be employed.

The substrate temperature at the time of forming a deposited film in the present invention may be any temperature as long as the film is formed. For example, when an amorphous silicon (A-Si) film is deposited, it is preferably 20 ° C. The temperature is not less than 500 ° C and more preferably not more than 50 ° C and not more than 450 ° C.

As the source gas for forming the deposited film, any known gas can be selectively used depending on the type of the film to be formed. For example, in the case of forming an A-Si based functional deposition film, for example, silane (SiH ₄ ), disilane (Si ₂ H ₆ ) and the like are mentioned as preferable source gases, and another functional deposition film is formed. If so, a raw material gas such as germane (GeH ₄ ) or methane (CH ₄ ) or a mixed gas thereof may be used. Examples of the carrier gas include hydrogen (H ₂ ), argon (Ar), helium (He), and the like.

Further, as a characteristic improving gas for changing the band gap width of the deposited film, for example, an element containing a nitrogen atom such as nitrogen (N ₂ ) and ammonia (NH ₃ ), oxygen (O ₂ ), nitrogen oxide (NO) ), Elements containing oxygen atoms, such as nitrous oxide (N ₂ O),
Methane (CH _4), ethane (C ₂ H _6), ethylene (C ₂ H _4),
Hydrocarbons such as acetylene (C ₂ H ₂ ) and propane (C ₃ H ₈ ),
Examples thereof include fluorine compounds such as silicon tetrafluoride (SiF ₄ ), disilicon hexafluoride (Si ₂ F ₆ ), and germanium tetrafluoride (GeF ₄ ), or a mixed gas thereof.

It is equally effective in the present invention to simultaneously introduce dopant gases such as diborane (B ₂ H ₆ ), boron fluoride (BF ₃ ), and phosphine (PH ₃ ) into the discharge space for doping. .

An example of a procedure for actually forming a deposited film by the method and apparatus of the present invention as described above is shown in FIG.
This will be described below with reference to FIG. That is, first, the inside of the reaction vessel 101 is evacuated by a vacuum pump (not shown) through the exhaust pipe 104, and the pressure in the reaction vessel, that is, the internal pressure is reduced to 1 × 10 ⁻⁷ To
Adjust to less than rr. Then, by heater 107,
All cylindrical substrates (105-1 to 105-6) are heated and maintained at a temperature suitable for film deposition. Therefore, in the case of forming an amorphous silicon deposition film, for example, a source gas such as a silane gas or a hydrogen gas is introduced into the reaction vessel 101 via a gas introduction unit (not shown). Simultaneously therewith, a microwave having a frequency of 500 MHz or more, preferably 2.45 GHz is generated by a microwave power supply (not shown), and the microwave is generated in the reaction vessel 101 through the waveguide 103 and the dielectric window 102. To be introduced. Further, at least one of the bases 105-1 to 105-6 has a frequency of 50 from the AC power supply units 111 to 113.
Apply an AC voltage of 0 Hz or more and 2 MHz or less. Thus, in the discharge space 106 formed by being surrounded by the plurality of cylindrical substrates (105-1 to 105-6), the raw material gas is excited by microwave energy to be dissociated, and further, the electric field between the raw material gas and the cylindrical substrates is increased. While constantly receiving ion bombardment on the cylindrical substrate, all the cylindrical substrates (105-1 to 105-
This is where the deposited film is formed on the surface of 6). At this time, by rotating all the cylindrical substrates (105-1 to 105-6) around the apparent central axis in the reaction vessel in the generatrix direction, the individual cylindrical substrates are deposited on the entire surface thereof. A film is formed.

Hereinafter, the effects of the present invention will be specifically described using experimental examples.

<Experimental Example 1 and Comparative Experimental Example 1> Using the apparatus shown in FIGS. 1 (A) and 1 (B),
According to the conditions for forming the deposited film shown in Table 1, a deposited film was formed on an aluminum cylindrical substrate having a diameter of 108 mm, a length of 358 mm, and a thickness of 5 mm according to the procedure described above. (Experimental Example 1) On the other hand, a deposited film was formed in the same manner as in Experimental Example 1 except that the method of applying a voltage to the substrate in Table 1 was changed as shown in Table 2.

(Comparative Experimental Example 1) Defects of the two types of samples prepared in this manner were compared and evaluated by microscopic observation of the surface, and a DC electric field was applied to a discharge space by applying a DC voltage to one of the conventional substrates. Compared to the sample in which the deposited film was formed on the substrate (Comparative Experimental Example 1), in the sample of Experimental Example 1 according to the present invention to which the AC voltage of the specific frequency was applied, the number of defects observed on the surface of the deposited film was very small. Turned out to be less.

<Experimental Example 2> The frequency of the AC voltage applied to the base 105-1 was changed from 60 Hz to 3
A deposited film was formed in the same manner as in Experimental Example 1 except that the frequency was changed to MHz. The measurement results of the surface defects and the electrical characteristics of the sample thus manufactured were compared with those of Comparative Example 1 described above.
The results are shown in Table 3 together with the results.

In Table 3, the electrical characteristics were evaluated by placing the prepared sample in a copier NP7550 manufactured by Canon Inc. modified for characteristic evaluation, applying a voltage of 6 kV to the charger, and charging. A probe of a surface electrometer 344 manufactured by Trek was installed at the position of the developing device of the copying machine, and the surface potential of the dark part and the surface potential of the bright part on the sample were measured. Among the evaluation items, the characteristic unevenness was represented by the difference between the dark area surface potential of the sample to which a voltage was applied during the formation of the deposited film and the sample to which no voltage was applied. The evaluation of the number of image defects was performed by counting the number of white spots of 0.3 mm or more within a certain area of the image sample obtained when the sample was placed in the remodeling apparatus, the black original was placed on the platen, and the image was copied. . For both characteristic unevenness and image defects, the measurement results obtained when a DC voltage was applied to the substrate during formation of the deposited film (sample of Comparative Experimental Example 2) were 10%.
The relative values were set to 0%. (The smaller the number, the better the result.) As is clear from these experiments, in order to obtain a deposited film having good electric characteristics at high speed, a voltage is applied to a part of the base and an electric field is applied to the discharge space. However, in order to obtain a deposited film with good electrical characteristics and few defects at high speed, the voltage applied to a part of the substrate is set to AC, and the frequency is 500 Hz or more, 2 MHz or less, Better than 2kHz, 500
It turned out that it is necessary to set it to kHz or less.

Hereinafter, the present invention will be described with reference to examples and comparative examples, but the present invention is not limited to these examples.

<Example 1> An AC voltage was applied to three substrates No. 105-2, 105-4 and 105-6, and the other conditions were the same as in Experimental Example 1 except that the other substrates were grounded. An electrophotographic photosensitive drum was manufactured. The manufactured photosensitive drum is manufactured by Canon Inc.
When an image was copied using the NP8582 copying machine, a very good image with good image contrast, excellent gradation reproducibility and excellent image resolution with no image defects was obtained.

<Example 2> An electrophotographic photosensitive drum was manufactured under the same conditions as in Examples 1 and 2, except that the number of substrates 105 surrounding the discharge space 106 was changed.

When the number of bases 105 was increased from six to eight, and even to ten each, as long as the substantial volume of the discharge space 106 did not change significantly, good results almost similar to those obtained in Example 1 were obtained. was gotten.

Comparative Example 1 An electrophotographic photosensitive drum was manufactured using the deposition film forming apparatus shown in FIGS. 6A and 6B under the conditions shown in Table 1. At this time, no voltage was applied to any of the substrates 605-1 to 605-6, and the substrates were grounded. Microscopic observation showed that the deposited film thus produced had very few defects and was good, but good images could not be obtained because of its low electrical chargeability and large residual potential.

<Comparative Example 2> Electrophotographic exposure was performed under the same conditions as in Comparative Example 1 except that a DC voltage was applied to the electrode 412 in the discharge space by the deposition film forming apparatus shown in FIGS. 4 (A) and 4 (B). A drum was made. By increasing the voltage applied to the electrode 412,
The electrical characteristics of the deposited film on the substrate 405 improved, and at 50 V, the quality reached a product level, and an image with good contrast was obtained. However, image defects increase as the voltage applied to the electrode 412 increases, and when the voltage is 50 V or higher, the yield of the product is reduced and the cost is increased.

<Comparative Example 3> Electrophotography was performed in the same manner as in Comparative Example 1 except that a DC voltage was applied to one base 605-1 by the deposition film forming apparatus shown in FIGS. 6 (A) and 6 (B). A photosensitive drum was manufactured. Substrates 605-2 to 605-6 other than the substrate 605-1 were grounded. Although the electrical characteristics of the base 605-1 were not improved by increasing the voltage applied to the base 605-1, the base 605-1 to which no DC voltage was applied was observed.
The electrical properties of the deposited film on 2-605-6 improved,
At 0 V, it reached the level of the product and an image with good contrast was obtained. However, image defects increase as the voltage applied to the substrate 605-1 increases, and if the voltage is 50 V or more, the yield of products is reduced and the cost is increased.

Comparative Example 4 The same as Comparative Example and Comparative Example 2 except that a 60 Hz sine wave AC voltage was applied to the base 605-1 in the deposited film forming apparatus shown in FIGS. 6 (A) and 6 (B). An electrophotographic photosensitive drum was produced by the method. By increasing the voltage applied to the base 605-1, the base 605-1 and the other base 605-2 are increased.
The electrical properties of the deposited film on 605-6 increase,
In the case of V, all the photosensitive drums reached the product level, and images with good contrast were obtained. However, at any voltage, the characteristic unevenness due to the position of the deposited film is large, and the image defect due to the defect of the deposited film increases as the voltage applied to the base 605-1 increases. Yield decreased and product cost increased.

[Brief description of the drawings]

1 (A), 1 (B), 2 and 3 are views for explaining a deposited film forming apparatus of the present invention. 4th
(A), FIG. 4 (B), FIG. 5, FIG. 6 (A), and FIG. 6 (B) are views for explaining a conventional deposited film forming apparatus. In the figure, 101,201,401,601 ... film forming furnace, 102,402,602 ... microwave introduction window, 103,403,603 ... waveguide, 104,404,604 ... exhaust tube, 105,405,605 ... substrate, 106,406,606 ... discharge space, 107,407,607 ... heater, 109,209,409,609 ... Rotating shaft, 110, 410, 610: Motor, 111: Oscillator, 112
... Filter part, 113 matching part, 411, 611 DC power supply, 412 electrode, 213 vacuum sealing means, 214 fixing means, 215, 218, 221 insulator, 216 rotational transmission means, 217 …… Brush, 219 …… Coaxial cable, 220…
... Cooling water introduction means.

Claims (4)

(57) [Claims] A plurality of substrates are disposed in a substantially hermetically sealable reaction vessel so as to surround a discharge space for performing discharge by microwave energy from microwave introduction means. A method for forming a deposition film on the surface of the substrate by forming a discharge plasma containing a reactant contributing to film formation derived from the method, wherein at least one of the substrates includes the substrate and at least one other than the substrate. The frequency is 500Hz or more, so that an electric field is formed between
A method for forming a functional deposited film, characterized by applying an AC voltage of MHz or less. 2. The method of claim 1, wherein said substrate is cylindrical. 3. A plurality of substrates are arranged in a substantially hermetically sealable reaction vessel so as to surround a discharge space in which discharge by microwave energy from microwave introduction means is performed. An apparatus for forming a deposited film on the surface of a substrate by forming discharge plasma containing a reactant contributing to film formation derived from the substrate, wherein the substrate is formed so that an electric field is formed between the substrate and the substrate. An AC power supply for generating an AC voltage having a frequency of 500 Hz or more and 2 MHz or less is electrically connected to at least one of the above. 4. The apparatus according to claim 3, wherein said substrate is cylindrical.