JPH0456773A - Plasma CVD equipment - Google Patents

Abstract

PURPOSE:To form a high-quality thin film excellent in adhesion by generating a plasma discharge region having an optimum density for exciting and decomposing the raw gases for each raw gas. CONSTITUTION:When a TiCN film is formed, a supply system 7, nozzle 3 and mesh electrode 5 are provided for each of the raw gases such as TiCl4, NH3 and CH4, and an optimum high-frequency power for exciting and decomposing each gas is supplied from the respective high-frequency power sources 9. The raw gas is blown off from the blowoff port 4 of the nozzle 3, excited and decomposed in the plasma discharge region, and the positive ion necessary to form a thin film is strongly attracted by a substrate 6 which is heated to an appropriate temp. by a heater (not shown in the figure) provided at the bottom of a holder 2, etc., and provided with a negative potential by a DC power source 8. Consequently, a high-quality thin film excellent in adhesion is formed on the substrate 6 by the bonding of the ions.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plasma CVD apparatus capable of coating thin films of metals, fine ceramics, etc. with excellent adhesion at low temperatures.

[Conventional technology]

In recent years, it has become common practice to coat base materials such as steel with metals, ceramics, etc. to improve wear resistance and increase the reliability of the base material. This is carried out by a plasma CVDN1 such as the above.

As shown in the figure, from the center of the vacuum chamber 11 there is a raw material gas supply pipe +2, an inner cylindrical electrode 13, and an outer cylindrical electrode I4.
are arranged coaxially (see figure (0)). First, the raw material gas supply pipe 12 has a coaxial double pipe structure, has a large number of pores 12a along the outer circumferential direction and the longitudinal direction of each pipe, and is connected to the raw material gas supply system 18. Next, an inner cylindrical electrode 13 located on the outer periphery of the pipe 12 is connected to a high frequency power source 15 with a mesh structure. Furthermore, an outer cylindrical electrode 14 located on the outer periphery of the inner cylindrical electrode 13
also has the role of a substrate holder, on the inner periphery of which the substrate 17 can be attached, and is connected to the negative terminal of the DC power source I6.

Then, the inside of the vacuum chamber Il is set to a predetermined pressure, the base material is heated to a predetermined temperature, and the raw material gas is supplied from the pores 12a,
A predetermined power is applied from both sources 1B and 17. Then, the source gas is excited and decomposed in the plasma discharge region, forming a thin film on the surface of the base material.

[Problem to be solved by the invention]

By the way, in the conventional apparatus described above, all the raw material gases necessary for coating are supplied from the pipe 2 connected to a single supply system 18, and the high frequency power to be applied is also supplied from a single power supply 16.

However, each type of raw material gas molecule has its own ionization potential, and the degree of excitation and decomposition of each type is very often different at the same plasma density. For example, when coating a composite film of TIN and Tic or a thin film of TlCN, TiCl4 + is used as the raw material gas.
NH3 and CH4 are used, and the first ionization potential of each is +1.78.10.15.12.75eV
Unlike, IIH3 is easily decomposed by plasma discharge, whereas CH14 is difficult to decompose.

For this reason, it is not only difficult to obtain a stoichiometric film, but also unreacted carbides are incorporated into the film, causing a decrease in the performance of the film.

In addition, in order to completely decompose CH4, by increasing the radio frequency power and increasing the plasma density, N[13, TlCl
Radicals generated from No. 4 and higher-order radicals generated by reactions between radicals were generated, causing abnormal discharge.

Therefore, an object of the present invention is to provide a plasma CVD apparatus that can generate a plasma discharge region with an optimal density to excite and decompose each raw material gas, and can perform high-quality coating, in order to solve the above-mentioned drawbacks. There is a particular thing.

[Means to solve the problem]

In order to achieve the above object, the plasma CVD apparatus of the present invention includes a plurality of nozzles arranged in a vacuum chamber, each connected to an independent raw material gas supply system, and with its outlet facing toward the substrate. , Mesh electrodes of the same number as the nozzles are arranged between the holder to which the base material can be attached and each of the nozzles, facing each of the nozzles, each of the nozzles is grounded, and each of the mesh electrodes is connected to an independent high-frequency power source. The holder is connected to the negative terminal of a DC power source so that a negative potential can be applied to the base material, and a heater is provided outside or inside the vacuum chamber.

[Effect]

As mentioned above, for each type of raw material gas, the supply system, nozzle,
By making mesh electrodes independent, each source gas is excited,
It can supply the optimal high frequency power for decomposition. This solves the problem that existed in conventional devices, where depending on the type of raw material gas, there would be an excess or deficiency in the high-frequency power required for excitation and decomposition.

Further, the raw material gas blown out from the nozzle is excited and decomposed in the plasma discharge region and turns into positively charged ions and negatively charged electrons, but the components necessary for forming a thin film are positive ions. In order to form a thin film with excellent adhesion on the surface of a substrate, it is necessary to attract these ions to the substrate and increase the degree of impact on the substrate. Therefore, by applying a negative potential to the base material, positive ions are strongly attracted to each other, and a thin film with excellent adhesion is formed on the base material due to the bonds between the ions.

〔Example〕

The present invention will be explained below based on the embodiment shown in FIG.

First, let's start with the mechanical configuration of the device.

■Vacuum chamber 1 This is cubic in shape and has an exhaust system (not shown)
The internal pressure can be adjusted to a predetermined level.

■Holder 2 This is a cylindrical pedestal located approximately in the center of the vacuum chamber 1, and is used to mount the base material 6. Note that the substrate may be configured to be rotatable.

■Nozzle 3 It has a shape that widens at the tip, and is equipped with a large number of air outlets 4 at the tip. In the example, 8) are arranged. Each of these nozzles 3 is connected to an independent raw material gas supply system 7, and by setting different types of raw material gas in each supply system 7, a different raw material gas can be blown out from each nozzle.

(2) Mesh electrodes 5 Mesh electrodes 5 have the same number of mesh electrodes as the nozzles 3, and are arranged between the holder 2 and the nozzle 3, facing the nozzle 3. The dimensions of this mesh are such that they do not impede the flow of the raw material gas, and each mesh electrode has a configuration in which the distance from the nozzle 3 (or the distance from the base material) can be adjusted independently, making it easy to form a thin film. The optimum spacing can be selected (for example, if the mesh electrode is too close to the substrate, a mesh pattern may be formed on the thin film).

■Heater (not shown) Heats and adjusts the substrate to a predetermined temperature, and is provided inside the vacuum chamber (inner wall of the vacuum chamber, bottom of the holder 2, etc.) or outside.

Next, let's talk about the electrical configuration.

■Holder 2 Connected to the negative terminal of the DC power supply 8. Since the base material mounting surface of the holder 2 is conductive, a negative potential can be applied to the base material from the power source 8.

Note that the positive terminal of the power source 8 is grounded.

■Nozzle 3 Each is grounded (not shown).

■Mesh electrodes 5 Each is connected to one terminal of an independent high frequency power source 9. This allows the high frequency power to be controlled independently for each mesh electrode.

The other terminal of the power source 9 is grounded.

■High frequency power supply All power supplies 9 are connected to an out-of-phase signal generator 10.

Therefore, the high frequency signals of each power source 9 can generate plasma without interfering with each other.

The base material is installed in the above-mentioned apparatus, and the pressure in the vacuum chamber and the temperature of the base material are maintained at predetermined conditions. Then, while supplying each raw material gas, the optimal high-frequency power to excite and decompose it is supplied to Metsu7.
A thin film is formed by applying a negative potential to the Y electrode and further applying a negative potential to the base material.

[Test example]

A TlCN film was coated using the above apparatus.

Using a cubic vacuum chamber with sides of 60 cm, a base material of 2 hm x 20 mm and 3 mm thick was placed on a holder of 20 CIlφ.
I installed the SK■9 board. In addition, as a raw material gas for TlCN, TlCl4. NH,,CH2 are used, but TlC
Since l4 is a liquid at room temperature, H2 is used as a carrier gas,
Ar was used to stabilize the plasma. The nozzles that blow out each of these raw material gases are for mixed gas of TLC14 and ■2,
Four electrodes, one for Ar, one for Ni13, and one for CH2, are used, and the electrodes facing each nozzle are each IKv.

High-frequency power of 1.5 Kv, 1.5 Kw, and 3 Kv is applied.

The mesh electrode used here had a mesh size of 5 io+, and the DC bias applied to the base material was -200V. Then, the inside of the vacuum chamber was evacuated to 0.2 Torr, and the substrate temperature was heated to 500°C using a resistance heating type heater.
Time coating was done.

As a result, the film thickness was 2. TlC with a mountain glossy purple color
A N film could be formed. The adhesion of this Tl0N film was measured using A and E scratch testers.
The value was as high as 0 to 35N, and it was confirmed that the adhesive had excellent adhesion.

〔Effect of the invention〕

As explained above, by generating a plasma discharge region with the optimum density for each source gas to be excited and decomposed, and eliminating negative effects such as residual unreacted gas and abnormal discharge due to higher-order radicals, A thin film with excellent adhesion and high quality can be formed.

[Brief explanation of drawings]

FIG. 1 is a plan view of an apparatus according to an embodiment of the present invention, and FIG. 2 shows a conventional apparatus, in which (a) is a longitudinal sectional view and (b) is a cross-sectional view. 1, ll... Vacuum chamber, 2... Holder 3... Nozzle, 4... Air outlet, 5... Mesh electrode, 6.1
7... Base material, 7.18... Raw material gas supply system, 8.1
6...DC power supply, 9.15...High frequency power supply, IO/
...Different phase signal generator, 12... Raw material gas supply pipe,
12a... Pore, 13... Inner cylindrical electrode, 14...
・Outer cylindrical electrode.

Claims (1)

[Claims] (1) A vacuum chamber is equipped with a plurality of nozzles each connected to an independent raw material gas supply system and arranged with their blow-off ports facing the direction of the substrate, and a holder on which the substrate can be attached and a holder for each of the nozzles. In between, the same number of mesh electrodes as the nozzles are arranged facing each nozzle, each nozzle is grounded, each mesh electrode is connected to an independent high frequency power source, and a negative potential is applied to the base material. A plasma CVD apparatus characterized in that the holder is connected to a negative terminal of a DC power supply to enable the plasma CVD to be carried out, and a heater is provided outside or inside the vacuum chamber.