JPS6247484A - Device for forming deposited film by plasma cvd - Google Patents

Abstract

PURPOSE:To form a good-quality deposited film without any damage on a substrate uniformly, homogeneously, steadily and stably by providing an electrode for collecting charged particles on the central part of a reaction vessel and circumferential arranging a rotatable cylindrical substrate with the electrode as the center. CONSTITUTION:A rotatable cylindrical substrate 6 is held by a holding means 61 equipped with a heating means 62 in a reaction chamber B, a high-frequency wave or a microwave generated from an oscillator 32 is introduced through a dielectric window 3 to generate plasma to excite a raw gas supplied from an inlet 5, and a thin film is deposited on the substrate 6 by the reaction in a deposited film forming device A by CVD. In the device, an electrode 7 for collecting charged particles is provided on the central part of the reaction chamber B and the cylindrical substrates 6 are coaxially and circumferentially arranged with the electrode 7 as the center. A negative voltage is impressed on the electrode 7 by a DC electric power source 72. The charged particles are collected and discharged by an exhauster 42 from a gap part 4. Consequently, neutral radical particles are moved to a side wall 1 and a deposited film is efficiently formed on the substrate 6.

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 photosensitive device for electrophotography, a line sensor for image input, and an imaging device. The plasma C
This invention relates to a device using the VD method.

[Description of prior art]

Conventionally, semiconductor devices, photosensitive devices for electrophotography,
Element members used for image input line sensors, imaging devices, photovoltaic elements, etc. include amorphous silicon, such as amorphous silicon (hereinafter referred to as RA) compensated with hydrogen and/or halogen (e.g. fluorine, chlorine, etc.)
5i (denoted as h, χ month) membranes, etc. have been proposed, and some of them have been put into practical use.
i (H, χ) together with their a-3i (H, X)
Several methods for forming films and equipment have been proposed, including vacuum evaporation, ion blating, so-called CVD, plasma CVD, and photo-CVD.
Among them, the plasma CVD method has been put into practical use as the most suitable method and is generally widely used.

By the way, in the plasma CVD method, a deposited film forming gas is excited and speciated (radicalized) in the vicinity of the substrate surface using high frequency or microwave energy to cause chemical interaction, and a film is deposited on the substrate surface. However, the devices shown in FIGS. 5 and 6 have been proposed as an alternative device.

That is, FIG. 5 is a schematic cross-sectional view of a deposited film forming apparatus using the conventional plasma CVD method, and FIG. 6 is a schematic cross-sectional view of the apparatus shown in FIG. 5 taken along line 1--1.

In the figure, A represents the side wall 11, the bottom wall 11', and the lid part 11.
The whole apparatus having a reaction chamber B formed in a sealed manner is shown in FIG. 13 is a cylinder made of a conductive material such as metal, and has a plurality of perforations in the side wall; 15. The cylinder is erected in the center of the reaction chamber B with its bottom fixed to the central axis, and its bottom is connected to an exhaust system 14 provided outside. 12,12. . . , a cylindrical substrate placed on a substrate holding means incorporating a heating means 17 and mechanically connected to the rotation means 16 at the bottom, as shown in No. 6i4, VC centered on Yen 1 and 13,
They are arranged and installed on the same circumference with predetermined intervals maintained. and base bodies 12, 12. ... are electrically grounded 19 together with the side wall 11 so that both are held at the same potential. Reference numeral 15 denotes a gas introduction system, through which raw material gas is supplied into the reaction chamber B through pipe means. Reference numeral 18 denotes a high frequency power generation source, one end of which is electrically connected to the conductive cylinder 1, and the other end electrically grounded 19. Note that the conductive cylinder 16 and the cylindrical base 1
2,12. ... respectively act as a cathode electrode and the latter as an anode electrode during operation of the device.

The above-described film forming operation using a deposited film forming apparatus using the conventional plasma CVD method is performed in the case where, for example, an a-3i (H, χ) deposited film is formed. The cylindrical substrates 12 and 1 are placed in the cylindrical substrates 12 and 1 by operating the exhaust system 14 to create a vacuum inside the reaction chamber B.
2. ... are heated to a predetermined temperature by their respective heating means 17, and the raw material gas Nrankas is introduced into the reaction chamber B via the gas j9 human system 15, and at the same time, coupled to the high frequency power generation source 18. Then, high-frequency power is applied to the quadrilateral cylinder 13, and the rotation mechanisms 16, 16° . . . This is done by rotating... When operated in this manner, the cylinder 16 acts as a cathode electrode and the cylindrical substrate 12, 12 . acts as an anode electrode. A plasma discharge is generated between them, thereby exciting and decomposing the /lan gas, and chemical interaction occurs between them, so that a-31, (H, X) A film is deposited.

(The conventional plasma CVD shown in FIGS. 5 and 6)
Although the apparatus for forming a deposited film by the method has been adopted as a suitable one, there are some problems in operation.

That is, when a high frequency voltage is applied to the cylinder 15, the reaction chamber B
The gas molecules of the raw material gas (for example, run gas) introduced into the chamber are excited and decomposed to become plasma, and become electrons, ion particles, neutral radical particles, etc. These particles are deposited on rotating cylindrical substrates 12, 12 . ... fly to the vicinity of each surface and form a deposited film. Here, what contributes to the formation of the deposited film is mainly neutral radical particles, but there are also many electrons and ion particles in the plasma, so in the process of film formation, the electrons and ion particles The ion particles collide with the deposited film during or after formation, resulting in the creation of structural defects such as gungling bonds and voids, which deteriorate the quality of the formed film. This has been a major problem in forming a deposited film of high quality and uniform properties.

[Purpose of the invention]

The present invention overcomes the problems in conventional devices as described above, and provides semiconductor devices, photosensitive devices for electrophotography, line sensors for image input, imaging devices, photovoltaic devices, various other electronic devices, optical devices, etc. The deposited film as an element member used for
The purpose of this invention is to provide a wafer device that can be formed stably on a regular basis.

That is, the main object of the present invention is to eliminate damage to the deposited film due to plasma collision, to make it uniform and homogeneous, and to constantly and stably form a deposited film of good quality and excellent desired characteristics. An object of the present invention is to provide an apparatus for forming a deposited film using a CVD method.

Still another object of the present invention is to provide a plasma that can easily control the thickness and quality of the deposited film to be formed, and can form a deposited film with a uniform thickness distribution and uniform quality. An object of the present invention is to provide an apparatus for forming a deposited film using a CVD method.

[Structure and effect of the invention]

The present inventor has discovered the conventional plasma CV shown in FIGS. 5 and 6.
As a result of extensive research in order to overcome the above-mentioned problems with the D-method deposited film forming apparatus and achieve the above objectives, we found that when a charged particle collection electrode is provided in the center of the conventional apparatus, The present invention has been completed by solving the various problems described by AiT regarding the conventional device and by obtaining knowledge that enables the above-mentioned object of the present invention to be achieved.

That is, in the apparatus of the present invention, on a substrate installed in a reaction chamber,
In a deposited film forming apparatus using a plasma CVD method that uses high frequency waves or microwaves to form a deposited film, an electrode for capturing charged particles is provided in the center of the reaction chamber, and a concentric circle is formed around the electrode. It is characterized by being provided with a rotatable base body installation means.

In the apparatus of the present invention, charged particles that are undesirable for film formation are captured by the collection electrode, so there is no chance for such charged particles to reach the substrate surface, and therefore, they may not be present during or after formation. This eliminates the possibility of colliding with the deposited film and causing structural defects in the deposited film, and (1) uniformity of the electric field strength distribution of the emitted high frequency or microwave near the substrate is promoted, which makes it possible to improve the efficiency of the conventional device described above. In addition to being able to significantly improve the film formation speed in comparison, it is also possible to constantly and stably mass produce deposited film products that are excellent in all aspects such as quality, thickness, and electrical, optical, and photoconductive properties. .

The raw material waste used to form the deposited film by the apparatus of the present invention is of the kind that is excited by frequency or microwave energy and chemically interacts with it to form the desired deposited film on the substrate surface. Any type of material can be used as long as it is, but for example, a-8i (H,
X) If a film is to be formed, specifically, materials in a gaseous state such as 7ranes and halogenated silanes in which hydrogen, halogen, or hydrocarbon, etc. are bonded to silicon, or materials that are easily gasified. Gasified materials can be used. You can use one type of these raw material gases (
Alternatively, two or more types may be used in combination.

Further, these raw material gases may be used after being diluted with an inert gas such as He or Ar. Furthermore, a-3i
(The E(, / and can be mixed with a diluting gas and introduced into the reaction chamber.

The substrate may be conductive, semiconductive, or electrically insulating, and specific examples thereof include metal, ceramics, glass, and the like. The substrate temperature during the film forming operation is not particularly limited, but is generally in the range of 30 to 450°C, preferably 50 to 350°C.

In addition, when forming a deposited film, the pressure inside the reaction chamber is set to 5X10-6 Torr at rq+j where the raw material gas is introduced.
Hereinafter, it is preferably 1X1O-6 Torr or less, and when the raw material gas is introduced, the pressure inside the reaction chamber is 1X10''.
~I Torr, preferably 5 X 10-” ~I
It is desirable to set it to Tarr.

Note that the deposited film formation by the apparatus of the present invention is usually performed without pre-treating (exciting speciation) the raw material gas as described above (introducing it into a reaction chamber, where it is excited and specidizing with high frequency or microwave energy). This is carried out by causing chemical interaction, but when using two or more types of raw material gases, it is also possible to excitedly species one of them in advance and then introduce it into the reaction chamber. .

Hereinafter, the apparatus for forming a deposited film using the plasma CVD method of the present invention will be explained in more detail with reference to the embodiments shown in FIGS. 1 to 4, but the apparatus is not limited thereto.

1 and 2 are schematic cross-sectional views of a deposited film forming apparatus using the plasma CVD method of the present invention, and FIGS. 3 and 4 are cross-sectional views of the apparatus along the II-In line and the III-In line, respectively. This is a schematic diagram.

In FIG. 1, A shows the entire apparatus for forming a deposited film by the plasma CVD method of the present invention, which has a reaction chamber B sealed with a side wall 1, a bottom wall 1', and a removable lid part 2.

The lower side is a dielectric window through which high frequency or microwave waves propagating through the waveguide 61 from the high frequency or microwave oscillator 32 are radiated into the reaction chamber B. As shown in FIG. 6, reference numeral 4 denotes an exhaust gap portion that circularly surrounds the dielectric window 3, is insulated from the waveguide 31, and is open into the reaction chamber B. , communicates with a conduit 41 which is connected via a valve 43 to an exhaust device 42 . 5 is an inlet for introducing raw material gas into the reaction chamber B, and is connected to a gas supply source 51 via a valve 52 .

Reference numeral 7 denotes an electrode for capturing charged particles, which is made of a conductive material such as aluminum or stainless steel, and its tip is located at the center of the space above the dielectric window B, that is, at the center of the reaction chamber B. As shown in FIG. They are connected via means 76. 61
is a holding means for the cylindrical substrate 6 containing a heating means 62, and as shown in FIG. 6, is located in the reaction chamber B,
A plurality of electrodes are installed around the charged particle collection electrode 7 and coaxially with the charged particle collection electrode 7 on the same circumference at a predetermined interval (at least one distance). The substrate holding means 6i, 6i, .
. . , and the supporting legs are respectively supported by external rotary drive means 64, 64 . It is mechanically connected to... and can rotate in either left or right direction.

The support legs 63 , 63 , . . . are respectively attached to the side wall 1
Both are electrically grounded 8 and held at the same potential.

In the deposited film forming apparatus A according to the plasma CVD method of the present invention shown in FIGS. 1 and 3 described above, high-frequency or Plasma discharge is induced by the microwave radiation, which excites and decomposes the source gas, but the charged particles that are generated at this time and are undesirable for film formation are drawn into the collection electrode and are exhausted by the exhaust device 42. As a result, neutral radical particles, etc., which are generated and which contribute to film formation, descend in the system and are discharged from the gap 4.
For example, if the source gas is SiH4, Si", SiH"
, SiH2'', etc., proceed in the direction of the side wall of the reaction chamber B due to the shoring action of the rotating cylindrical substrate 6, 6, etc., and are uniformly dispersed near the surface of each substrate. A deposited film is formed by uniformly depositing on each substrate surface through reactions with the substrate surface, reactions with each other, reactions with specific components in the introduced raw material gas, etc. In the device of the present invention, problems of structural defects caused by collisions of electrons and ion particles and problems of impurity contamination, which are seen in conventional devices, do not occur, and problems such as quality, thickness, electrical, optical, and photoconductive properties do not occur. A desired deposited film product excellent in all aspects of physical properties can always be obtained stably and efficiently.

The apparatus shown in FIGS. 2 and 4 is similar to that shown in FIGS.
This is a modification of the apparatus shown in the figure, and is also a preferred embodiment of the apparatus for forming a deposited film by the plasma CVD method of the present invention.

In the apparatus shown in FIGS. 2 and 4, the exhaust port is an opening 4 in the side wall 1 of the reaction chamber B, and a dielectric window 6 for radiating high-frequency waves or microwaves into the reaction chamber B is provided. A high frequency or microwave waveguide 601 is sealed in the notch cut out in the center of the bottom wall of the reaction chamber and communicated with a high frequency or microwave oscillator 62 in the conductive window. is fixed. And charged particle collection electrode 7
As shown in FIG. 2, the electrode 01 has a closed end and a tubular shape having a large number of perforations 701', 701', . A raw material gas supply pipe communicating with a gas supply source 51 is provided as piping 50 . The electrode 701 is sealed and insulated 702 and fixed thereto at the penetration part of the lid part 2, and the electrode member is electrically connected to a DC power source 72 provided outside by a connecting means 73. There is.

In the deposited film forming apparatus A using the plasma CVD method of the present invention illustrated in FIGS. 2 and 4 described above, high frequency waves or microwaves are radiated into the reaction chamber B through the dielectric window 6. A plasma discharge is induced. Then, the holes 701', 701', . . . of the charged particle electrode 701
The raw material gas discharged in the direction of the arrow shown in the figure is excited and decomposed by the action of the plasma discharge caused above.
Charged particles that are generated at this time and are unfavorable for film formation are attracted along the wall surface of the member of the collection electrode 701, while neutral Rancal particles that contribute to film formation, for example, Si when the source gas is Si H4. ”, SIH”, SiH2”
etc. are the effects of the raw material gas flow discharged horizontally in the direction of the side wall of the reaction chamber B through the holes 701', 701', .
And rotating cylindrical bases 6,6. The action of...
Furthermore, due to the exhaust action of the exhaust device, the gas proceeds toward the side wall of the reaction chamber B and is uniformly dispersed near each substrate surface, causing reactions with the substrate surface, reactions with each other, and reactions in the introduced raw material gas. A desired deposited film is formed by uniformly depositing it on the surface of each substrate through reaction with a specific component, etc., as in the apparatuses shown in FIGS. 1 and 6.

Hereinafter, the formation of a deposited film by operating the deposited film forming apparatus using the plasma CVD method of the present invention will be explained using an example, but the following example does not have a limiting meaning to the operation of the apparatus. .

EXAMPLE A photoconductive deposited film was formed on the surface of an At cylindrical substrate by operating the deposited film forming apparatus using the plasma CVD method of the present invention shown in FIGS. 1 and 6.

That is, the thin At cylindrical substrates 6, 6, . . . are attached to the substrate holding means 61, 61, .・・・
・ was placed in the reaction chamber B, and the exhaust device 42 was operated and the valve 43 was adjusted to create a vacuum of about 10 −5 Torr. Then, the substrate temperature was maintained at about 300° C. by heating means 62. Next, SiH, which is the raw material waste for forming the deposited film, is
4 was diluted with hydrogen gas and introduced into the reaction chamber A through the inlet 5. When the gas flow rate becomes stable, adjust the exhaust valve 46 to reduce the internal pressure of reaction chamber B to approximately 2 x 10-' Torr.
It was set as r. When the internal pressure becomes constant, the rotation of the substrate holding means 6L61° is started, and then a negative DC voltage is applied to the electrode 7, and a microwave of 2.45 [) Hz is applied to the reaction chamber B. radiated. This state is maintained for 20 minutes, and the cylindrical bases 6, 6. ...a-8i(H,X
) was formed. After that, when the substrates were cooled to a predetermined temperature, they were taken out of the system and tested, and it was found that uniform and homogeneous deposited films were formed on all substrates, and all of them were rich in properties. Met.

[BRIEF DESCRIPTION OF THE DRAWINGS] Figures 1 and 2 are schematic cross-sectional views of the apparatus for forming a deposited film using the plasma CVD method of the present invention, and Figures 3 and 4 are the lines -■ and -, respectively, of the apparatus. ■It is a schematic cross-sectional view along the line. FIG. 5 is a schematic cross-sectional view of a deposited film forming apparatus using a conventional plasma CVD method, and FIG.
It is a schematic cross-sectional view taken along one line. In Figures 1 to 4, 1... side wall, 1'... bottom wall, 2... lid, 6...
- Dielectric window, 31... Waveguide, 62... High frequency or microwave oscillator, 4... Exhaust gap, 41...
Conduit, 42...Exhaust device, 43...Valve, 5...
Raw material gas inlet, 51... Raw material gas supply source, 52...
) i-lube, 6... Cylindrical base, 61... Base holding means, 62... Heating means, 66... Support leg, 64...
- Rotation drive means, 7... Charged particle collection electrode, 71...
・Insulation part, 72...DC power supply, 76...Lead wire,
A... Entire device, B... Reaction chamber, '501... Waveguide, 50... Piping connection part, 701... Charged particle collection electrode, 701'... Perforation, 702...・Insulation section. In FIGS. 1 and 2, 11...side wall, 11'...bottom wall, 11a...lid part,
12... Cylindrical base body, 13... Metal cylinder, 13a.
...perforation, 14...exhaust system, 15...gas introduction system,
16... Rotating mechanism, 17... Heating means, 18...
High frequency power generation source, 19...ground.

Claims (1)

[Claims] In a deposited film forming apparatus using a plasma CVD method that forms a deposited film on a substrate placed in a reaction chamber using high frequency waves or microwaves, an electrode for capturing charged particles is provided in the center of the reaction chamber. . A deposited film forming apparatus using a plasma CVD method, comprising: a base mounting means that is rotatable coaxially and circumferentially about the electrode.