JPH03274276A - Device for synthesizing thin film - Google Patents

Abstract

PURPOSE:To stably synthesize a thin film uniform in quality and thickness by converting a raw gas to plasma between a grounded electrode and substrate close to the gas outflow port to a second vacuum vessel in a first vacuum vessel and controlling both the vessels to a specified pressure. CONSTITUTION:The raw gas 9 contg. a thin film constituting element such as C6H6 is introduced into the first vacuum vessel 5. A grounded electrode 7 is set in the vessel 5, and the raw gas 9 is converted to plasma 6 between the electrode 7 and a substrate 1 on a substrate holder 2 connected to a high-frequency power source 3. Consequently, the raw gas 9 is excited and decomposed, and a thin film of a diamondlike substance, etc., is synthesized on the substrate 1. In this thin film synthesis device, the raw gas 9 is passed through the first vacuum vessel 5 and introduced into the second vacuum vessel 10 from a gas outflow part 4, and the substrate 1 is arranged close to the gas outflow part 4. Besides, the substrate 1 is set at such a position that the pressures of the vessels 5 and 10 are controlled respectively to >=0.01Torr and to <=5X10<-3>Torr. The plasma 6 is made uniform and stable in this way, and the quality and thickness of the thin film are uniformized.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a thin film synthesis apparatus for synthesizing thin films using ions in plasma.

2. Description of the Related Art Conventionally, various types of apparatuses for synthesizing diamond-like/If films have been disclosed. The RF plasma CVD apparatus shown in Fig. 3 will be explained below as an example of a conventional diamond-like thin film synthesis apparatus (for example, the 33rd Applied Physics Association Lecture Proceedings 3p-ZD-14).
etc.). FIG. 3(a) is a schematic configuration diagram of this device, and FIG. 3(b) shows the potential near the electrodes of the device. 5iO2 (glass) is placed as the base 25 on the lower electrode 26. Using benzene gas 24 as the raw material gas, 13.56MHz
When high frequency power is applied to the lower electrode 26 using the high frequency type R27, plasma 30 is generated, and a diamond-like thin film having a hardness of about 3000 is synthesized on the base 25.

As is clear from this conventional example, high-quality diamond-like thin films can be synthesized even on insulating substrates such as glass by using alternating current power such as high-frequency power.

In addition to this conventional example, an example is Patent No. 147943
2, the DC plasma CVD device, etc.
Various apparatuses for synthesizing diamond-like thin films are known;
In either case, it is generally believed that high-quality diamond-like thin films can be synthesized by bombarding the surface of the substrate with sufficient kinetic energy by ions in the plasma. Third
Figure (b) explains the principle by which a high-quality diamond-like thin film is synthesized using the conventional synthesis apparatus. Same (b
), 2 indicates a so-called self-bias voltage generated in the base 25, and 2 indicates a self-bias voltage generated in the upper electrode 23. This self-bias voltage is generated so that the substrate and the electrode have a relatively low potential with respect to the plasma. The ions are accelerated in the direction of the substrate 25 by this (1) and impact the surface thereof. Here, Vl and ■2 are the area of the lower electrode 260 A1 and the plasma 3 in the conventional example.
If the area of the upper electrode 23 and the vacuum vessel 28 that are in contact with 0 is written as A2, it is expressed as Vl/V2= (A2/AI) n (for example, from Brian N. Chapman, Translated by Yukio Okamoto, Basics of Plasma Processing, see p. 145, etc.). Here, n depends on the plasma state, the shape of the device, etc., and is generally 1 to 4. As shown in Figure 3,
Since A2 also includes the vacuum vessel 28, A + < A 2 and V2 < Vl.

In addition, since the absolute value of v2, ■1 depends on the plasma density, the value of ■1 can be checked by the magnitude of the high frequency power applied, and as specified in the conventional example above, it is sufficient It is possible to make it larger. As a result, a diamond-like thin film with sufficient ion kinetic energy and high quality was synthesized.

Problems to be Solved by the Invention However, in the conventional technique, the diamond-like thin film synthesized on the substrate 25 suffers from unevenness in film quality such as hardness, and unevenness in film thickness, which poses a problem.

This is because, as shown in Figure 3(a), in conventional thin film synthesis equipment, unevenness occurs in the gas flow state, gas pressure, and even plasma state due to the substrate, electrodes, vacuum container, etc. .

Furthermore, depending on the synthesis conditions, such as when high-frequency power is increased, abnormal discharge such as arc discharge may easily occur between the lower electrode 26 and the vacuum vessel 28 shown in FIG. It was difficult to synthesize it stably. This is because, as mentioned above, the gas pressure on the second day of the vacuum vessel is close to the pressure near the electrode where the membrane is synthesized, and the vacuum vessel 28 also serves as a ground electrode with respect to the lower electrode 25 to which power is applied. This is because plasma is generated throughout the vacuum container 28, and arc discharge is likely to occur on deposits, protrusions, etc. of the vacuum container 28.

Means for Solving the Problems A first aspect of the present invention is a first vacuum vessel which is provided with a flow part and an outflow part for raw material gas containing constituent elements of a thin film, and which converts this gas into plasma; a second vacuum container connected to the first vacuum container so that gas can flow between a ground electrode installed in the container and a gas outlet of the first vacuum container; The first vacuum container includes a base disposed close to the gas outlet so as not to obstruct the outflow of the gas from the gas outlet, and an AC power source that applies AC power to the base. A thin film characterized in that the substrate is placed at a position where the pressure in the first vacuum container is 0.01 Torr or more and the pressure in the second vacuum container is 5 X 10-3 Torr or less during synthesis. It is a synthesis device.

A second aspect of the present invention includes a first vacuum container that includes an inlet and an outlet for raw material gas containing constituent elements of the thin film, and that converts the gas into plasma; an electrode installed in the first vacuum container; a second vacuum container connected to the first vacuum container such that gas can flow between the first vacuum container and the gas outlet of the first vacuum container; a base disposed close to the gas outflow portion so as not to obstruct the gas outflow, an AC power source for applying AC power to the electrode, and a grounding member for the base; A thin film synthesis apparatus characterized in that the substrate is installed at a position where the pressure of the first vacuum container is 0.01 Torr or more and the pressure of the second vacuum container is 5 x 10-3 Torr or less. be.

In the first aspect of the present invention, the gas flow state, gas pressure, and plasma state at the thin film synthesis position are made uniform, so that the film quality and thickness become uniform. Furthermore, since the pressure in the first vacuum container is 0.01 Torr or more, which is higher than the pressure in the second vacuum container, plasma is likely to be generated in the first vacuum container. Furthermore, since the pressure in the second vacuum vessel outside the thin film synthesis section is set to 5X 10-3 Torr or less, generation of plasma and arc discharge in the second vacuum vessel are suppressed. As described above, the first invention solves the problems encountered in the prior art. In addition, the self-bias voltage (denoted as V3) generated on the substrate, which was necessary to synthesize a high-quality diamond-like thin film, is determined by dividing the self-bias voltage of the ground electrode by ■4 and the area of the substrate in contact with the plasma by A3. , if the area of the ground electrode is written as A4, then
As in the conventional example, V3/V4=(A4/A3)'. Therefore, the magnitude of the AC power to be applied, A4, A3
By adjusting V3 according to the ratio of ions, ions obtain sufficient kinetic energy, and a high quality diamond-like thin film can be synthesized.

Further, the second invention maintains the advantages of the first invention, such as being able to synthesize a thin film with uniform thickness and quality, and also exhibits the following effects. In the first invention, AC power is applied to a substrate placed in a second vacuum container. Therefore, the second vacuum vessel becomes a ground electrode for this substrate. In this case, the pressure in the second vacuum container is 5 x 10-3
Even with Torr, for example, if the applied AC power becomes larger than a certain level, plasma may also be generated in the second vacuum container, which is not very preferable. Further, when synthesizing a diamond-like thin film while rotating a cylindrical substrate, for example, the thin film synthesizing apparatus of the first invention cannot be said to be the best. The joint that applies AC power to the cylindrical base has a complex multi-point contact structure, and the impedance of this joint is high, so AC power is consumed and the temperature tends to increase. This is because abnormal discharges such as arc discharges are likely to occur. As a result, it is somewhat difficult to stably synthesize a diamond-like thin film on such a rotating cylindrical substrate. The second invention is a thin film synthesis apparatus that can further solve these disadvantages. In the second invention, AC power is applied to an electrode installed inside the first vacuum container, and the base is grounded, so that the base and the second vacuum container are at the same ground potential. As a result, generation of plasma in the second vacuum container can be suppressed more than in the first invention. Furthermore, problems such as power consumption, heat generation, and arc discharge at the joint where AC power is applied to the rotating cylindrical base as described above can be solved. In addition, the self-bias voltage (denoted as V5) generated on the substrate, which was necessary to synthesize a high-quality diamond-like/iI film, is determined by the self-bias voltage of the ground electrode being V6, and the area of the substrate in contact with the plasma. If A5 is the area of the ground electrode, and A6 is the area of the ground electrode, in this case as well, VS/V6=(AI3/A5)' as in the conventional example. Therefore, the magnitude of the AC power to be applied is 80, A5
By adjusting (5) according to the ratio, ions obtain sufficient kinetic energy and a high-quality diamond-like thin film can be synthesized.

Examples Examples of the present invention will be described below with reference to the drawings. 1st
The figure shows an embodiment of a thin film synthesis apparatus based on the first invention. Ordinary blue plate crow (thickness 1rl) is used as the insulating substrate l.
After installing the IITl) on the base holding member 2 made of stainless steel 'i14 and adjusting the interval between the gas flow parts 4 to 2 mm, the first vacuum container 5 and the second vacuum container 10 are connected to the vacuum pump 1.
1, and evacuated the second vacuum container 10 to 10"'To
It should be about rr. Next, benzene gas 6 is introduced into the first vacuum container 5 from the gas inlet 8 at 0.1 Torr, and 170 W of high frequency power is applied from the 13.56 MHz high frequency type R3 to the substrate holding member 2. Plasma 6 was generated between the insulating substrate 1 and the ground electrode 7 in the vacuum container 5 . At this time, the pressure in the second vacuum vessel 1O was 7×10-' Torr, and no plasma was generated in this vacuum vessel. Further, the self-bias voltage at the substrate 1 was 560 . In this state 1
Synthesized for 0 minutes. The synthesized film has a Knoop hardness of 3000
to 3100A, and the film thickness is 5500A to 57A.
It is a diamond-like thin film with a uniform quality of 00A.

In addition, increasing the high frequency power increases the synthesis rate of the diamond-like thin film, which is advantageous in terms of production. Arc discharge started to occur.

Furthermore, in the embodiment shown in FIG. 1, if the base body 1 is installed at a position where the interval between the gas outlet portions 4 is 10ffI111, the pressure of the first vacuum vessel 5 is 0 and I Torr, and the second vacuum vessel 10 is The pressure is 9 x 10-3 Torr
It became r. When high frequency power of 100 W was applied in this state, plasma was generated throughout the second vacuum vessel 10.

In addition, the Knoop hardness of the synthesized film is 1
The film thickness varied from 800A to 2900A at the center, and the film thickness also varied from 2600A at the periphery to 4100A at the center. Note that the above-mentioned interval varies depending on the size of the first vacuum container 5, the size of the second vacuum container 1O, the exhaust capacity of the vacuum pump 11, etc., and the present invention is not limited thereto.

Further, in the present invention, a diamond-like thin film can be synthesized under synthesis conditions other than those in the above embodiments. For example, if the power source is an AC power source, a thin film on diamond can be synthesized on an insulating substrate, and the frequency of the high frequency power source may be 27 MHz, or an audio frequency of about 100 kHz may be used. Various hydrocarbon gases such as ethylene and methane can also be used as the raw material gas. Other synthesis conditions are not limited to those described above. Further, a DC voltage may be superimposed at the same time as the AC power is applied.

It goes without saying that high-quality diamond-like thin films can be synthesized even when the substrate is conductive.

Furthermore, the present invention is applicable to the synthesis of thin films other than diamond-like thin films. Further, the first vacuum container 5 is taken out to the outside of the second vacuum container 10, a hole is made in the arm of the second vacuum container 10, and the gas outlet part 4 of the first vacuum container 5 is connected to the hole. It may be configured as follows.

FIG. 2 shows an embodiment of a thin film synthesis apparatus based on the second invention. In this embodiment, a tram-shaped device 41!, which is widely used in copying machines and the like, is used. Demonstrates the synthesis of a diamond-like thin film on a sensual body. FIG. 2 shows a side view of the organic photoreceptor. The organic photoreceptor (indicated by a base 12 in FIG. 2) has an organic insulating layer 1 on a conductive member 12-2 such as aluminum.
2-1 is formed. This organic photoreceptor is installed on a rotating support member (not shown), and the conductive member 12-2 is grounded by a grounding member 22. Further, after adjusting the interval between the gas flow sections 130 to 2 mrn, the first vacuum container 14 and the second vacuum container 19 are evacuated by the vacuum pump 21, and the second vacuum container 19 is heated to 10-5 Torr. degree. Next, benzene gas 18 is introduced into the first vacuum container 14 from the gas inlet 17 at a pressure of 0.1 Torr, and at a pressure of 1 Torr.
When 170 W of high frequency power was applied to the electrode 16 from the 3.56 MHz high frequency power source 20, plasma 15 was generated between the base 12 and the electrode 16 in the first vacuum vessel 14. At this time, the pressure in the second vacuum container 19 is 8
10-' Torr, and no plasma is generated in this vacuum vessel.

Further, the self-bias voltage of the substrate 12 was 560V. Synthesis was carried out in this state for 10 minutes. The synthesized film had a Knoop hardness of 3,000 to 3,100, and a uniform film thickness of 6,500 to 5,700 A, which was a diamond-like thin film of good quality.

Furthermore, although increasing the high frequency power increases the synthesis rate of the diamond-like thin film, in this example, no plasma was generated in the second vacuum vessel 19 even at approximately 1000 W.

Furthermore, in the embodiment shown in FIG. 2, if the interval between the gas outlet parts 13 is 10 mm, the pressure in the first vacuum container 14 is 0,
At 11'orr, the pressure in the second vacuum vessel 19 is 0.
．． It became 02 Torr. In this state, the high frequency power is
When 0 is applied, the plasma 15 leaks from the gas outlet part 13 to the second vacuum container 19.
Plasma was generated throughout. In addition, the Knoop hardness of the synthesized film ranges from 1800 at the periphery of the composite area to 2 at the center.
900, and on the other hand, the film thickness was 260 in the peripheral area.
Unevenness occurred from 0 A to 4100 A in the center. In addition,
The distance varies depending on the size of the first vacuum vessel 14, the size of the second vacuum vessel 190, the evacuation capacity of the vacuum pump 20, etc., and the present invention is not limited thereto.

Further, in the present invention, a diamond-like thin film can be synthesized under synthesis conditions other than those in the above embodiments. For example, if the power source is an AC power source, a thin film on diamond can be synthesized on an insulating substrate, and the frequency of the high frequency power source may be 27 MHz, or an audio frequency of about 100 kHz may be used. Various hydrocarbon gases such as ethylene and methane can also be used as raw material gases. Other synthesis conditions are not limited to those described above. Further, a DC voltage may be superimposed at the same time as the AC power is applied. It goes without saying that a diamond-like thin film of good quality can be synthesized even if the substrate is conductive.

Furthermore, the present invention provides diamond-like 1i11! It can also be applied to the synthesis of other thin films.

Effects of the Invention As is clear from the above explanation, the thin film synthesis apparatus of the present invention is capable of synthesizing a high-quality diamond-like thin film on an insulating substrate with uniform thickness and quality, and is capable of producing a diamond-like thin film with uniform thickness and quality. It can be widely applied to surface protective films of various electronic devices, optical parts, etc., and has great industrial effects.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of the thin film synthesis apparatus of the first invention, FIG. 2 is a schematic sectional view showing an embodiment of the thin film synthesis apparatus of the second invention, FIG. 3 is a schematic sectional view showing a conventional thin film synthesis apparatus. 1.12...Base, 3,20...High frequency 'F#LH
14゜13... Gas outflow part, 5, 14... First vacuum container, 6.15... Plasma, 7... Ground electrode,
16... Electrode, 10.19... Second vacuum container.

Claims (2)

[Claims] (1) a first vacuum container that includes an inlet and an outlet for a raw material gas containing constituent elements of the thin film and converts the gas into plasma;
A second vacuum container is connected to the first vacuum container so that gas can flow between a ground electrode installed in the first vacuum container and a gas outlet of the first vacuum container. a vacuum container; a base body disposed close to a gas outlet portion of the first vacuum container so as not to obstruct gas flow from the gas outlet portion; and an AC power source for applying alternating current power to the base body; and the pressure in the first vacuum container is 0 during synthesis of the thin film.
．． 01 Torr or more and the pressure of the second vacuum container is 5×
A thin film synthesis apparatus characterized in that the base body is installed at a position where the pressure is 10^-^3 Torr or less. (2) a first vacuum container that includes an inlet and an outlet for a raw material gas containing constituent elements of the thin film and converts this gas into plasma;
a second vacuum container connected to the first vacuum container so that gas can flow between an electrode installed in the first vacuum container and a gas outlet of the first vacuum container; a base body disposed close to the gas outlet part of the first vacuum container so as not to obstruct the outflow of the gas from the gas outlet part; an AC power source that applies alternating current power to the electrode; and a grounding member for the base body, and the pressure in the first vacuum container is 0.01 Torr or more and the pressure in the second vacuum container is 5×10^-^3 Torr or less during synthesis of the thin film. A thin film synthesis device characterized in that a base is installed.