JPH11268164A - Base material with carbon film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film containing a carbon film as a main component on a surface to be formed with good adhesive properties by providing a film having a small internal stress on a layer in contact with a base plate, and laminating films having sequentially larger internal stresses as separating from the plate in a laminating direction. SOLUTION: Films having sequentially larger stresses are formed likewise by forming a film to be laminated and having a smallest stress and then a film to be laminated and having next smaller stress on the previous film on a film formed in direct contact with a base plate. For example, a silicon nitride 24 is formed on a layer in contact with the plate, and a carbon film 25 is formed thereon. To this end, a hydrogen silicide gas such as, for example, a silane, nitrogen, ammonia are introduced into a reaction system, and then a hydrocarbon gas and nitrogen are similarly introduced. As the hydrocarbon, a gas of a methane hydrocarbon or the like, a silicon carbide like a tetramethylsilane partly containing silicon or a carbon chloride like a carbon tetrachloride may be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The composite coating according to the present invention is a coating containing carbon or carbon as a main component (hereinafter referred to as a carbon-based coating) by improving interfacial properties, particularly adhesion, to an underlying substrate, particularly a substrate having an oxide surface. This is to maximize the characteristics such as abrasion resistance, high smoothness, and high hardness, which are the characteristics of the film.

[0002]

2. Description of the Related Art Conventionally, attempts have been made to form carbon-based coatings on a wide variety of base materials. However, satisfactory interfacial properties, especially adhesion, cannot be obtained due to differences in base materials. At present, the advantages of carbon-based coatings cannot be fully demonstrated, and the development of new technologies is urgent.

[0003]

The conventional single-layer carbon-based coating has poor interfacial adhesion with the base material in application thereof,
For example, when a carbon film formed at a high temperature of 350 ° C or more is returned to room temperature, the carbon film is detached or peeled off, or when a carbon film formed at a room temperature is heat-treated at a high temperature of 400 ° C or more, In this case, spot-like peeling or detachment of the film occurs.

[0004] The former is generally called thermal stress, in which stress is inherent due to a difference in thermal expansion (shrinkage) rate with the substrate, and the latter is caused by a decrease in CH bonds (hydrogen content) in the film. This is because the effect of relaxing the stress by hydrogen is reduced. An object of the present invention is to solve the above problems and to provide a film having a carbon-based film as a main component on a surface on which a carbon film is to be formed with good adhesion.

[0005]

According to the present invention, there is provided a composite coating in which two or more coatings are laminated on a substrate, wherein a layer in contact with the substrate is provided with a coating having the smallest internal stress among the coatings laminated. The above object has been achieved by sequentially laminating films having large internal stresses as they move away from the substrate in the laminating direction.

That is, a coating formed in direct contact with the substrate is formed by forming a coating having the smallest stress among the coatings to be laminated, and then forming a coating having the next lowest stress on the coating. They make a big thing.

In the present invention, for example, when considering a carbon-based coating, it is not discussed in a single layer, but is provided with good adhesion on the surface to be formed and good consistency with the surface to be formed. The purpose of this method is to form a composite laminated film that can make the most of the advantages of the film as a component.The relative relationship between the thermal stress and the hydrogen content in the film is controlled by the selection of the starting material gas and the film forming conditions. The above-mentioned object is achieved by controlling the residual stress of the film. Hereinafter, description will be made in accordance with embodiments.

[0008]

EXAMPLE In this example, silicon nitride was formed on a layer in contact with a substrate, and a carbon-based film was formed thereon. FIG. 1 shows a parallel plate type plasma apparatus. In a gas system (1), first, in order to form silicon nitride forming an interface with an underlying substrate, a hydrogen silicide gas such as silane, which is a reactive gas, is used.
Disilane is introduced from (2) into nitrogen and ammonia is introduced from (4) through a flow meter (8) via a valve (9) into a reaction system (11) from a nozzle (10).

On the other hand, when forming a carbon-based coating, 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 the hydrocarbon gas include methane, ethane, ethylene,
Gases such as methane-based hydrocarbons (C _n H _{2n + 2} ) or when partially containing silicon, tetramethylsilane ((CH ₃ ) ₄ Si), tetra-eral silane ((C ₂ H ₅ ) ₄ Si) And carbon chloride such as carbon tetrachloride (CCl ₄ ).

Inert gas is used as a pre-treatment gas because carbon trifluoride, which is an etching gas for the film, is derived from (5), oxygen is derived from (6), and depending on the base material, plasma cleaning is required. It is also possible to introduce a gas, for example argon (7).

In the reaction system (11), the formation of a silicon nitride film and a carbon-based film and the etching thereof are performed under reduced pressure. In the reaction system (11), the first electrode (13) and the second electrode (13)
, A pair of electrodes (13) and (14) installed on the high-frequency power supply side, a high-frequency power supply (16),
Matching transformer (17), DC bias power supply (1
From 8), electric energy is applied and plasma (15)
Occurs. As a result, desired silicon nitride films and carbon-based films are formed.

Unnecessary substances after the reaction are exhausted through a pressure adjusting valve (19), a turbo molecular pump (20), and a rotary pump (21) of an exhaust system. As described above, the composite laminated film (23) is formed on the base material (22) shown in FIG. 2 in a laminated structure of the silicon nitride (24) and the carbon-based film (25). Is established.

In this embodiment, the film formation conditions are as follows: a silicon nitride film has a reaction temperature of 150 ° C. to 350 ° C. and a reaction pressure of 0.01 to 0.
5 torr, an RF power density 0.1 ~0.3W / cm ² self-bias voltage _{-150~-250V, SiH 4, N} 2 is SiH ₄ as a raw material gas
By varying the / N ₂ ratio in the range of 0.05 to 0.5, the stoichiometric composition ratio was controlled, and the hydrogen content in the film could be similarly controlled in view of the film stress. Basically, the same method was used for the carbon-based coating.

That is, the reaction temperature is 150 ° C. to 350 ° C., and the reaction pressure is 0.
01 to 0.5 torr, high frequency power density 0.1 to 0.3 W / cm ² self-bias voltage -150 to -250V.

FIG. 3 shows the film stress when the thickness of the silicon nitride film forming the layer in contact with the base substrate in the composite laminated film according to the present invention is varied, and the total stress when the carbon-based film is further laminated. However, in the silicon nitride single layer,
1 × 10 ⁹ dyn / cm ² to 2.7 even if variable from 50Å to 5000Å
It is a range of compressive stress of × 10 ⁹ dyn / cm ² and does not show much dependency on film thickness.However, lamination of a carbon-based film 5,000 mm results in film thickness dependency of the underlying silicon nitride film, In a thin region, the total stress is large, and the relaxation effect is not exhibited. However, in a film region around several thousand mm, the total stress tends to decrease while having the same compressive stress.

This is because the presence of silicon nitride alleviates lattice mismatch, and alleviates stress strain by improving thermal stress.

FIG. 4 shows a composite laminated film according to the present invention.
This graph shows the stress when the thickness of the single layer of the upper carbon-based film is varied. The film stress of this film tends to increase with the film thickness as a whole stress, that is, the stress integrated in the film thickness direction. It turns out that some means is necessary to bring out the maximum.

When this film is applied as a single layer, there is no problem if the desired film thickness is small, but if the film thickness is large, the film has properties that spread to cracks and peeling due to release of stress. It is.

[0019]

According to the present invention, in the application of a carbon-based coating which has been regarded as difficult in the past, a great improvement effect can be obtained by forming the composite multilayer coating on the interface characteristics, especially the initial stage and the change with time of the adhesion. Is caused. That is, it has become industrially practical for the first time by controlling the thermal stress by controlling the interfacial CO 2 bonding on the surface to be formed and controlling the hydrogen content in the film, that is, by reducing the total residual stress of the film.

[Brief description of the drawings]

FIG. 1 is a schematic view of a parallel plate plasma apparatus used for carrying out the present invention.

FIG. 2 is a cross-sectional view of a composite laminate film produced according to the present invention.

FIG. 3 is a graph showing a relationship between a film thickness and a film stress.

FIG. 4 is a diagram showing a relationship between a film thickness and a film stress of a film.

Claims (3)

[Claims] 1. A base material having an oxide surface, a first non-oxide film formed on the base material, and a carbon-based film formed on the first film. A substrate having a carbon-based coating characterized by having a carbon-based coating. 2. The substrate according to claim 1, wherein the internal stress of the first coating is smaller than the internal stress of the carbon coating. 3. The substrate according to claim 1, wherein the first coating is a silicon nitride coating.