JPH02215522A - Composite laminated film - Google Patents

Abstract

PURPOSE:To stick a film consisting mainly of a carbon film onto the surface to be formed, by a method wherein the film, whose stress is the lowest, out of the films to be laminated is formed by coming directly into contact with a board, a film, whose stress is low next to that of the first film, is formed over the first film and the film whose stress is higher is formed likewise in order. CONSTITUTION:Composite laminated films 23 are formed of a laminated structure comprised of silicon nitride and carbon films 24, 25 on a ground base material 22. Even if a thickness is varied from 50Angstrom to 5,000Angstrom in a laminated ply of silicon nitride, the same falls within a range of compression stress of 1X10<9>dyn/cm<2> to 2.7X10<9>dyn/cm<2> and does not shown so much dependence on a film thickness. However, the dependence of the film thickness of a silicon nitride film of a lower layer is generated, the whole stress in a sphere where the film thickness is thin is great, and mitigation effect is not displayed, by laminating the carbon film by 5,000Angstrom . However, even though compression stress is same, the whole stress is reduced, in a film thickness sphere around thousands of Angstrom .

Description

Detailed Description of the Invention "Field of Application of the Invention" The composite coating of the present invention improves interfacial properties, especially adhesion, to a base substrate, especially a substrate having an oxide surface. coating (hereinafter referred to as carbon-based coating)
This maximizes the opening characteristics of the steel, such as wear resistance, high smoothness, and high hardness.

``Prior Art'' Previous attempts have been made to form carbon-based films on a wide variety of base materials, but the current situation is that satisfactory interfacial properties, especially adhesion, cannot always be achieved due to differences in the underlying base materials. Therefore, the advantages of the carbon-based coating cannot be fully demonstrated.
There is an urgent need to develop new technologies.

``Problems with conventional technology'' Conventional single-layer carbon films have poor interfacial adhesion with the underlying substrate, for example, when a carbon film formed at a high temperature of 350°C or higher is returned to room temperature. The carbon film may detach or peel off, or the carbon film formed at room temperature may be heated to 400°.
When heat-treated at a high temperature of C or higher, spotty peeling or detachment of the film may occur in some areas. The former is generally referred to as thermal stress, and stress is inherent due to the difference in thermal expansion (contraction) rate with the substrate, while the latter is due to a decrease in the C-H bonds (hydrogen content) in the film, resulting in hydrogen stress. This is because the effect of relieving stress is reduced.

The present invention aims to solve the above-mentioned problems and to provide a coating mainly composed of a carbon-based coating on a surface to be formed with good adhesion.

[Means to solve the problem]

In the present invention, in a composite coating in which two or more coatings are laminated on a substrate, the layer in contact with the substrate is provided with a coating having the smallest internal stress among the laminated coatings, and as the layer moves away from the substrate in the lamination direction, Therefore, the above objective is achieved by sequentially laminating coatings with large internal stresses.

In other words, for the coatings that are formed in direct contact with the substrate, the one with the lowest stress among the stacked coatings is formed, and then the one with the lowest stress is formed on top of that coating, and so on. Let it form.

For example, when considering a carbon-based coating, the present invention does not discuss it in terms of a single layer, but rather provides it on the surface to be formed with good adhesion and good consistency to the surface to be formed, and as a result, the film has carbon or carbon as the main component. This method forms a composite laminated film that can maximize the advantages of the film, and the relative relationship between thermal stress and hydrogen content in the film is controlled by the selection of the starting material gas and film formation conditions, and the final film is The above objective is achieved by controlling the residual stress of

The following will be explained according to examples.

〔Example〕

In this example, silicon nitride was formed as a layer in contact with the substrate, and a carbon-based film was formed thereon.

Figure 1 shows a parallel plate type plasma apparatus.In the gas system (1), a reactive gas such as hydrogen silicide gas such as silane or disilane ( 2) Nitrogen and ammonia are introduced into the reaction system ODO from nozzle 0 through the flowmeter (8) and pulp (9) from (4).

On the other hand, when forming a carbon-based film, a hydrocarbon gas as a reactive gas is introduced from (3), and nitrogen is introduced from (4) through a flow meter (8) and a valve (9) in the same manner.

Examples of hydrocarbon gases include gases such as methane, ethane, ethylene, and methane hydrocarbons (CnHz-4g), or tetramethylsilane ((CH
z) n5i), tetraeralsilane ((ctus)
It may be silicon carbide such as 4Si) or carbon chloride such as carbon tetrachloride (CC14).

Carbon trifluoride (5), which is a gas for etching the film,
It is also possible to introduce oxygen (6) or, depending on the base material, an inert gas such as argon (7) as a pretreatment gas since plasma cleaning is required.

In reaction system 00, a silicon nitride film and a carbon-based film are formed and their etching process is performed under reduced pressure.
In D, a high frequency power source (16) and a matching transformer 07) are installed between the first electrode 0■ and the second electrode 04, that is, a pair of electrodes 03) and Q4) installed on the high frequency power supply side.

Electrical energy is applied by the DC bias power source 0, and plasma 0ω is generated.

As a result, the desired silicon nitride film and carbon-based film are formed.

Unwanted materials after the reaction are removed from the exhaust system using pressure regulating pulp 09. It is exhausted through a turbo molecular pump (to) and a rotary pump (21).

As a result of the above, the composite laminated film (23) is formed on the underlying base material (22) shown in FIG.
A method for forming a film was established to solve the problems of the conventional method.

In this example, the film forming conditions were as follows: for silicon nitride film, reaction temperature: 150°C to 350°C, reaction pressure: o, oi to 0.5°C.
torr, high frequency power density 0.1 to 0.3 W/cmg, self bias voltage -150 to -250 V, and raw material gases 5iHa and Nt have a 5ins/Ng ratio of 0.05.
The hydrogen content in the film could be controlled in a similar manner in consideration of the film stress by varying the stoichiometric composition ratio by varying the range of 0.5 to 0.5. Furthermore, the same method was basically used for carbon-based coatings.

That is, reaction temperature 150℃~350℃ 1 reaction pressure 0.01~
0.5torr+high frequency power density 0.1~0.3W/c
m'' self-bias voltage is -150 to -250v.

Figure 3 shows the film stress when varying the film thickness of the silicon nitride film that forms the layer in contact with the underlying base material in the composite laminated film according to the present invention, and the total stress when a carbon-based film is further laminated. However, in a single layer of silicon nitride, the compressive stress ranges from 1 x 10 drop dyn/cm" to 2.7 Although it does not show much, by stacking 5000 carbon-based films, a dependence on the thickness of the underlying silicon nitride film occurs, and the total stress is large in areas where the film thickness is thin.
Although the relaxation effect is not exerted, the total stress tends to decrease even though the compressive stress remains the same in the film thickness region of around several thousand layers.

This is because stress strain is alleviated by improving lattice mismatch and thermal stress due to the presence of silicon nitride.

Figure 4 shows the stress when the film thickness of the upper carbon-based single layer is varied in the composite laminated film according to the present invention. It can be seen that there is a strong tendency for the stress integrated in the direction to become high, and that some means is necessary to get the most out of the report.

When applying this film as a single layer, if the desired film thickness is thin,
Although this is not a problem, it has physical properties that can lead to cracks, beading, etc. due to the release of stress due to its thickness.

``Effects'' According to the present invention, when applying carbon-based coatings, which have been considered difficult in the past, the concept of composite laminated coatings can significantly improve interfacial properties, especially changes in adhesion, both initially and over time. It is something.

That is, it has become industrially practical for the first time due to the effect of inhibiting interfacial C--O bonds on the surface to be formed and the control of thermal stress by controlling the hydrogen content in the film, that is, the reduction of the total residual stress of the film.

[Brief explanation of the drawing]

FIG. 1 shows an outline of a parallel plate plasma apparatus used to carry out the present invention. FIG. 2 shows a cross section of a composite laminated coating prepared according to the present invention. FIG. 3 and FIG. 4 are diagrams showing the relationship between the film thickness of the film and the film stress.

Claims (1)

[Claims] 1. In a composite film in which two or more films are laminated on a substrate, the layer in contact with the substrate is provided with the film with the smallest internal stress among the laminated films, and A composite laminated coating characterized by coatings with increasing internal stress being stacked one after another as they move away from each other. 2. A composite laminated film according to claim 1, characterized in that a silicon nitride film is formed on the layer in contact with the substrate, and a carbon or carbon-based film is formed on the layer.