JPS61238962A - Method and apparatus for forming film - Google Patents

Abstract

PURPOSE:To form a high-hardness carbon film, etc., having uniform quality with high efficiency in an optional range with the less elevation of base body temp. by exciting a carrier gas and gaseous monomer to the plasma state and injecting the plasma to the base body while accelerating the ion seeds in the plasma. CONSTITUTION:The base body 11 to be formed with the film is disposed in the 2nd vacuum vessel 2 and the inside of the 1st vacuum vessel 1 made of a non-magnetic material and the vessel 2 are evacuated to a vacuum. The carrier gas 5 and the gaseous monomer 6 are introduced into the vessel 1 when the degree of vacuum attains a prescribed value. After the inside of the vessel 1 is regulated to the prescribed gaseous pressure, high-frequency electric power is impressed to an excitation coil 3, then the gas in the vessel 1 is excited to form plasma. The ions in the plasma are accelerated toward the base body 11 when a prescribed potential difference is provided between an acceleration electrode 9 and the base body 11 disposed in the vessel 1. The ions are injected from a plasma injection part 13 and collide against the surface of the base body 11. The electrons, neutral seeds and active seeds in the plasma arrive together with the ions in the viscous flow state of the gaseous plasma at the surface of the base body 11.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a plasma CVD method in which a single gas or a mixture of a carrier gas and a monomer gas is turned into plasma, and ion species in the plasma are accelerated and injected onto a substrate to form a film. and its manufacturing equipment.

BACKGROUND OF THE INVENTION Conventional technology is rapidly progressing, and the formation of polymer thin films and etching of silicon wafers have been put into practical use industrially. Recently, it has been reported that plasma is used to form a high-hardness carbon film that exhibits properties such as hardness, coefficient of friction, thermal conductivity, light transmittance, and specific resistance that are close to those of diamond. (Setaka et al., Proceedings of the Japan Society of Applied Physics Academic Lectures, Autumn 1982 J30
p-Y-8, etc.) High-hardness carbon films are used as solid lubricant films and passivation films for semiconductors because their properties are similar to those of diamond.

Although it is expected to be applied as a protective film for optical components, it is still in the laboratory prototype stage and has not yet been put into practical use.

Conventional methods and apparatus will be described below, taking the formation of a high-hardness carbon film as an example.

Conventionally reported methods for forming hard carbon films using plasma are broadly classified into PVD methods and CVD methods. FIG. 4 shows a conventional example of the plasma CVD method, which is an example of the CVD method. (Tezuka et al. [Proceedings of the 45th Japan Society of Applied Physics Academic Conference J, 1984, I) 214] In this conventional example, acetylene gas 21 is used as the monomer gas, and it is introduced into the glass tube 14 and brought to an appropriate pressure. Hold. A DC voltage is applied between the negative electrode 16 and the positive electrode 19 by the DC power source 19 to generate DC glow discharge plasma, and the thermal decomposition of the acetylene gas 21 by the filament 16 and thermionic electrons emitted from the filament 16 generate a DC glow discharge plasma. Promoting plasma formation. In this conventional example, in order to decompose carbon-hydrogen bonds using thermal energy on the substrate 18, reduce residual hydrogen in the formed film, and improve film properties, the substrate 18 is energized to SOO~1ooQ°C by the substrate heating power source 20. It's heating up.

In addition, the film forming speed of this conventional example is approximately 400A/
It is min.

FIG. 6 shows an outline of the ionization vapor deposition method, which is an example of the PVD method. (Kumada et al., Proceedings of the Academic Lectures of Japan Society of Applied Physics, 1986)
Autumn, 9a-T-4). In this conventional example, methane gas is used as a monomer gas, and thermal decomposition and ionization are performed by the heated filament 26 and thermionic electrons emitted by the filament 26.

At this time, an external coil 27 provided outside the filament 26
By generating a magnetic field, thermionic electrons move in a spiral pattern, promoting ionization. The ionized particles are accelerated by applying a negative bias to the upper mesh electrode 24 to form a film on the base 29. In this conventional example, the base 29 is also used to remove residual hydrogen in the formed film.
is heated by a heater 22. In addition, the ion particles accelerated at high speed collide with the base 29, causing the base 2 to
9 Temperatures rise, reaching as much as 400-700'C.

Problems to be Solved by the Invention Among the conventional methods for forming high-hardness carbon films, it has been reported that films having properties and structures extremely similar to those of diamond are formed. However, all of these are at the laboratory stage, and there are many problems with practical application. The problems are described below.

The first problem is an increase in temperature of the substrate. This is a problem common to both CVD and PVD methods. In particular, in the CVD method, as mentioned above, it is necessary to thermally decompose the C-H bond using thermal energy, and the substrate temperature is lowered to 700°C using electrical heating, a heater, a filament, etc. The temperature has already risen above ℃. Even in the PVD method, the temperature of the substrate is still increased as a means of reducing residual hydrogen in the formed film, or in many PVD methods, a negative bias voltage is applied to the substrate or an electrode provided near the substrate to ionize particles. are accelerated toward the substrate, and as the accelerated particles collide with the substrate, the temperature of the substrate inevitably increases. In this way, the conventional method increases the substrate temperature, so the substrate materials that can be used are limited.
The field of application will be extremely narrow.

The second problem is that the film formation rate is low.

In the conventional method of forming a high-hardness carbon film, plasma formation is promoted by applying a magnetic field using an external coil, using thermoelectrons from a filament, etc., but the film forming speed is several tens to several hundreds.
, A/'min is the most, and the maximum is 1000.
A/'min, making it difficult for industrialization.

A third problem is the use of hydrogen as a carrier gas. In the conventional method, hydrogen gas is introduced for the purpose of removing residual hydrogen in the formed film, promoting the reaction of active species in the plasma, and suppressing graphitic carbon that progresses at the same time as diamond growth. Hydrogen gas has the danger of exploding when it reacts with oxygen gas, so leaks from vacuum containers and residual air must be carefully controlled, and exhaust treatment must be done by mixing inert gas to ensure that the concentration is below explosive. Special treatment such as evacuation is required.

The fourth problem is that the device configuration becomes complicated. As mentioned earlier, since hydrogen, an explosive gas, is used, special structures such as explosion-proof measures are required. Also, PvD
In this method, a high vacuum device of at least 10 tons or more is required to sufficiently accelerate the ions in the plasma. CVD
As mentioned above, in this method, a device for heating the substrate (for example, a heater) is required, making the device configuration complicated. As described above, the conventional high-hardness carbon film forming apparatus has a complicated structure and is not suitable for industrialization.

In addition, with conventional equipment, it is difficult to locally form a film because the entire substrate is exposed to plasma, and it is difficult to apply it to existing vacuum equipment (e.g., evaporation equipment, sputtering equipment, etc.) without damaging its function. I can't. Therefore, when introducing a high-hardness carbon film forming process to an existing production line, a completely new dedicated vacuum device is required, resulting in a huge equipment cost.

In order to solve the above problems, we have devised a new method and apparatus for forming a high-hardness carbon film.

This is equipped with a plasma generation section, a plasma acceleration section that accelerates ions in the plasma, and a plasma injection section that sprays plasma containing accelerated ions onto a substrate in one vacuum container.
Ions in the plasma are accelerated by an acceleration method in which at least one or more acceleration electrodes are provided in the plasma generation section and the plasma injection section, and a potential difference is provided between the acceleration electrode and the substrate/substrate installation stand or between the acceleration electrodes. It is sprayed onto the substrate. At this time, since the plasma flow in the vacuum container is a viscous flow, electrons, neutral species, and active species are also injected together with accelerated ions to form a film. We call this film-forming method the plasma injection CVD method (hereinafter referred to as Pl-CVD).
Figure 6 shows an example of the PI-CVD method. Argon gas is used as a carrier gas, and hydrocarbon gas (for example, CH4 gas) is used as a monomer gas, and these are introduced into the first vacuum container 31. By applying high frequency power from a high frequency power source 3a to an excitation coil 3o wound outside the first vacuum container 31, the introduced gas is turned into plasma. A potential difference is created between the accelerating electrode 33 provided in the plasma generation section or the injection section and the base 34 or the base mount 35, with the accelerating electrode 33 being at a ground potential and the base 34 and the base mount 35 being at a negative potential. The ions are accelerated in the direction of the substrate 34. At this time, since the plasma flow in the first vacuum container 31 is a viscous flow, plasma containing electrons and neutral species is injected onto the substrate 34 together with accelerated ions to form a film. The quality of the film formed by this method changes greatly depending on the negative potential value of the substrate 34 and the substrate mounting table 35, and as shown in FIG. 7, the film becomes harder as the negative potential value becomes larger. The potential state between the accelerating electrode 4 and the base 39 is shown in FIG. Potential gradient is accelerating electrode (ground potential)
It is not constant between 41 and the base body 39, but sharply increases in the vicinity of the base body 39. (Generally, the region where the potential gradient increases rapidly is called the sheath region).

Therefore, ions in the plasma are also rapidly attracted and accelerated near the base 39 and collide with the substrate 34 to form a film.

However, this method also has the following problems. The first problem is that since the base 34 and base mounting table 36 to which a negative potential is applied are installed in the second vacuum vessel 32, the inner wall of the second vacuum vessel and the base 34, which are at the same potential as the accelerating electrode 33,
Discharge is likely to occur between the substrate mounting table 35 and it becomes difficult to apply a sufficient negative potential. Second
The problem with this is that the film formation rate is slow. This is because an accelerating electrode 33 is placed between the excitation coil 30 and the plasma injection section 38.
is installed, the high-frequency power does not reach the injection part 38 and no plasma is generated thereby, and some of the ions, neutral species, etc. in the plasma generated in the plasma generation part are trapped in the accelerating electrode 33. It's useless.

The present invention solves the above-mentioned problems, and makes use of the advantages of the Pl-CVD method described above, while also making it difficult to generate electric discharge between the substrate/substrate installation stand and the inner wall of the second vacuum container.
The present invention provides a new PI-CVD method and apparatus with faster film formation speed.

Means for Solving the Problems The technical means of the present invention for solving the above-mentioned problems is to provide an apparatus consisting of two vacuum containers, in which a hydrocarbon gas is contained in the first vacuum container made of a non-magnetic material.

a plasma generation section that excites a mixed gas containing argon gas as a main component; an acceleration section that accelerates ions in the plasma;
The invention is equipped with a plasma injection unit that injects plasma onto a substrate placed in a second vacuum container, and is accelerated by an accelerating means configured such that at least a part of an excitation coil is located between an accelerating electrode and the substrate. A high-hardness carbon film or the like is formed by completely injecting a plasma stream containing the ions onto the substrate.

Function The present invention has the above-mentioned device configuration, thereby forming a highly efficient and homogeneous high-hardness carbon film etc. by injecting the plasma onto the substrate without loss while accelerating the ions in the plasma excited in the plasma generation section. can do. Furthermore, since the entire substrate is not exposed to plasma, the temperature of the substrate increases little, and by changing the shape of the plasma injection part, it is possible to form a film in any desired range. Further, a plasma generation section is provided within the first vacuum container.

By providing a plasma acceleration section and a plasma injection section, if the two vacuum vessels can be separated, the first vacuum vessel can be handled as a single unit, and the function of existing vacuum equipment will not be impaired. It can be easily applied and installed.

Embodiment FIG. 1 is a schematic diagram showing an embodiment of the Pl-CVD apparatus of the present invention. Place the substrate 11 on which a film is to be formed on the substrate installation stand 12 inside the second vacuum container 2, operate the vacuum pump with the needle pulps 7a and 7b closed,
The insides of a first vacuum container and a second vacuum container made of non-magnetic material are evacuated. After the degree of vacuum reaches at least about 10 Pa, gas to be turned into plasma (carrier gas 5, monomer gas 6) is introduced into the first vacuum container 1. In the embodiment, argon gas is used as the carrier gas and hydrocarbon gas is used as the monomer gas, and they can be supplied singly or simultaneously by adjusting the needle pulps 7a and 7b as necessary. After setting the gas pressure in the first vacuum container to a pressure of about 10 to 20 Pa by introducing a predetermined gas, when high-frequency power is applied from the high-frequency power 8 to the excitation coil 3, the gas in the first vacuum container 1 increases due to inductive coupling. It is excited and turns into plasma.

In this state, the DC power supply 1o is connected to the acceleration electrode 9 (for example, a mesh electrode) arranged in the first vacuum container 1 and the base 11.
When a potential difference of several hundreds 7 or more is provided between the plasma and the substrate installation table 12, ions in the plasma are accelerated toward the substrate 11, are ejected from the plasma injection part, and collide with the surface of the substrate 11.

At this time, the plasma gas is in a viscous flow state, and along with ions, electrons, neutral species, and active species in the plasma also flow into the substrate 1.
Reach the surface of 1.

It is desirable that the accelerating electrode 8 in the first vacuum vessel 1 be arranged such that at least a portion of the excitation coil 3 is located between the accelerating electrode 8 and the plasma injection section 13. This is because when the accelerating electrode 9 is placed between the excitation coil 3 and the plasma injection section 13, the high frequency is cut off by the accelerating electrode 9 between the accelerating electrode 9 and the plasma injection section 13, making it difficult for the gas to be excited. This is also to prevent part of the ions and active species in the plasma generated by the excitation coil 3 from becoming trapped in the accelerating electrode 9, which would slow down the film formation rate. FIG. 2 shows, for example, the argon gas pressure 5.
0Pa, hydrocarbon gas5. OPa, acceleration electrode 9 and substrate 1
The relationship between the high-frequency power and the film-forming rate when the position of the accelerating electrode 9 is changed by setting the potential difference between 1 and 1 at o and sKV is shown.

As is clear from FIG. 2, the acceleration electrode 9 is connected to the excitation coil 3.
If the excitation coil 3 is disposed between the acceleration electrode 9 and the plasma injection section 13, the deposition rate will not change even if the high frequency power is increased. When the accelerating electrode 9 is placed between the power source 13 and the power source 13, the deposition rate increases as the high frequency power increases and becomes constant at several tens of W or more. The film formation rate at this time is approximately 1.5 times as high as that in the configuration in which the accelerating electrode 9 is disposed between the excitation coil 3 and the plasma injection section 13.

Furthermore, when a potential difference is provided between the accelerating electrode 9 and the base 11 or the base 12, the base 11. The base mounting table 12 is preferably at ground potential. As mentioned earlier, this is the base 11
- If the substrate mounting table 12 has a negative potential, electric discharge is likely to occur between it and the inner wall of the second vacuum container 2, making it impossible to set a sufficient potential difference with the accelerating electrode 9. FIG. 3 shows a potential gradient when a potential difference is provided between the accelerating electrode 9 and the base 11 with the base 11 at ground potential. Ions in the plasma generated by the excitation coil 3 are rapidly accelerated toward the base 11 by the Coulomb repulsion with the accelerating electrode 9 in the sheath region.
Thereafter, it collides with the base 11 while gradually losing energy. In addition, at this time, the plasma gas is in a viscous flow state, which is also helped by the acceleration of the ions, and the electrons in the plasma together with the ions.

The neutral species and the active species simultaneously reach the surface of the substrate 11 and form a film. When plasma of a mixed gas of argon and hydrocarbon is injected onto the surface of the base 11 while accelerating the ions in the plasma, a carbon film containing trace amounts of argon and hydrogen is formed on the base 11, and the bond between them is Macroscopically it is amorphous, but microscopically it contains bonds similar to diamond and has extremely high hardness. In this example, a high-hardness carbon film having a micro-Vickers hardness of 3000 kLj/- or more could be formed. The film is transparent and has a refractive index of 2.
It was 0 to 2.4 (wavelength 6328 people).

As mentioned earlier, the film formation rate is 2000 to 3000V, which is about 2 to 1° higher than that of conventional CVD and PVD methods, and there is almost no temperature rise in the substrate 11 during the film formation process. The temperature was maintained at room temperature (the temperature rose by about 5° C. in 10 minutes of film formation). In this embodiment, inductive coupling using high frequency waves is used as a means for turning the mixed gas into plasma, but DC glow discharge or microwave discharge may also be used.

As mentioned above, in this example, the formation of a high-hardness carbon film has been explained, but there are other ways to form a film from a gaseous state (for example, S I H4 gas + CH4 gas → SiC film, TLCt
The P I -CVD method of the present invention is effective in cases where the film is formed using a gas (e.g., NH3 gas → Ti3N4 film, etc.).

Effects of the Invention As described above, according to the present invention, a high-hardness carbon film can be formed with high efficiency without heating the substrate, and it can be easily installed in existing vacuum equipment without impairing its function. It is extremely useful in practice.

[Brief explanation of drawings]

FIG. 1 is a principle diagram of a film forming apparatus in an embodiment of the present invention;
Fig. 2 is a characteristic diagram showing the results of an experiment using the same example, Fig. 3 is a characteristic diagram showing the potential state in the first vacuum vessel in the same example, and Fig. 4 is a characteristic diagram showing the potential state in the first vacuum vessel in the same example. FIG. 5 is a principle diagram showing an example of a conventional PVD device. FIG. 6 is a principle diagram showing an example of a conventional Pl-CVD device. FIG. 7 is a principle diagram showing an example of a conventional PVD device. A characteristic diagram showing a result of an experiment using an example of a Pl-CVD apparatus. FIG. 8 is a characteristic diagram showing the potential state in the first vacuum vessel in an example of a conventional Pl-CVD apparatus. It is a diagram. DESCRIPTION OF SYMBOLS 1...First vacuum container, 2...Second vacuum container, 3...Excitation coil, 9...Acceleration electrode, 11... -Base body, 13...Plasma injection part. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 High-frequency power (W) Figure 4 Figure 5 Figure 6 To the vacuum pump Figure 7 Basic 6th body installation table potential (KV) Figure 8 (1 Oka 111'' = Hino

Claims (6)

[Claims] (1) A film forming method in which a carrier gas and a monomer gas are excited into a plasma state containing ion species, radical species, neutral species, and electrons, and the ion species in the plasma are accelerated and injected onto a substrate to form a film. (2) The film forming method according to claim 1, which utilizes Coulomb repulsion as a method for accelerating ion species. (3) a first vacuum vessel, an excitation coil wound around the outside of the first vacuum vessel, and a plasma generation unit that converts carrier gas and monomer gas introduced into the first vacuum vessel into plasma by high-frequency inductive coupling; , an accelerating means for accelerating ion species in the plasma generated in the plasma generating section; a plasma injection port facing the second vacuum container and the substrate for injecting the plasma onto the substrate installed in the second vacuum container; A film forming device equipped with (4) The accelerating means for accelerating ion species in the plasma includes an accelerating electrode facing the plasma injection port in the plasma generation section, and the accelerating electrode is connected to a high potential between the accelerating electrode and the base or the base mounting table. 4. The film forming apparatus according to claim 3, wherein a potential difference is provided such that the film forming apparatus has a structure such that a potential difference is provided. (5) The film forming apparatus according to claim 4, wherein the accelerating electrode is arranged so that at least a part of the excitation coil is located between the accelerating electrode and the substrate or the substrate mounting table. (6) The film forming apparatus according to claim 4, wherein the substrate or the substrate mounting table is set to a ground potential.