JPH0254754A - Formation of film having controlled gradient composition - Google Patents

Abstract

PURPOSE:To form a thin film having a precise gradient composition with high efficiency by using plural targets dissimilar in components and moving a base material in the course of sputtering. CONSTITUTION:Plural targets different in components, such as SiO and C, are used, and a base material is moved in the course of sputtering and, if necessary, electric power to be impressed on respective targets is changed. The base material-moving velosity and the proportion of changes in the electric power impressed on the targets are properly selected, respectively, by which the composition in a film-thickness direction can be arbitrarily changed. By this method, the thin film having a gradient composition can be formed on the surface of all sorts of materials. Further, since the necessity of changing the components of an atmospheric gas in the course of sputtering is obviated, plasma is stabilized and the thin film can be formed with high efficiency.

Description

[Detailed Description of the Invention] <Industrial Application Fields> The present invention is applicable to electronic devices such as LSIs and wear-resistant coatings for mechanical sliding surfaces, as well as other functions on the surface of a substrate in various fields. The present invention relates to a method of forming a film with

(Prior art) The attachment of various coatings to the surface of a certain substrate that have properties that the substrate does not have is necessary in many other fields to enhance wear resistance and corrosion resistance. ing. The characteristics required of such a coating are that the outermost surface has a function that meets the purpose for which the coating is attached, such as wear resistance, and that it has a strong adhesion to the substrate and does not peel off easily. However, the two types of foreign substances that are commonly found are
The greater the difference in composition, the worse the adhesion, and since the coefficients of thermal expansion are also different between the two, they tend to peel off more easily. Therefore, for example, a method of changing the composition ratio of Si and C of a film in the thickness direction by applying it to the CVD method was published in JP-A-60-1.
84681, and a method of applying so-called reactive sputtering to similarly vary the composition of the film in the thickness direction was proposed in Japanese Patent Application Laid-Open No. 60-22156.
As shown in Publication No. 2, these methods all change the composition of the film in the thickness direction,
This technique aims to obtain a coating that satisfies both the properties required for the coating itself and the property that the coating firmly bonds with the substrate.

<Problem to be solved by the invention> However, the technique disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 184681/1981 uses a CVD method, and the film formation process requires a considerably high temperature atmosphere. Therefore, of course, plastic cannot be selected as the base material.
Even if it is metal, it is not possible to select materials that are sensitive to high temperatures, so there are limitations to the base material.Furthermore, the composition of the coating is limited to products of chemical reactions, and in general, pure metal coatings cannot be made. Furthermore, the coating produced by the CVD method has high crystallinity and is therefore unsuitable when an amorphous coating is desired.

Furthermore, although the technique disclosed in Japanese Patent Application Laid-open No. 60-221562 uses sputtering, it is reactive sputtering and therefore uses a reactive gas mixed with argon. At this time, the sputtering rate of the reactive gas is lower than that of argon, and as the rate increases, the rate of thin film formation decreases. Furthermore, since compounds are gradually formed not only on the substrate but also on the target due to the reactive gas, the sputtering rate further decreases, and the formation rate of the Fji film becomes extremely slow. Furthermore, since this method requires a certain gas partial pressure to be changed during sputtering, the plasma becomes considerably unstable, and it is considered that it is difficult to form a precise composition gradient in practice.

It is an object of the present invention to provide a method for solving the problems of the prior art described above and forming a thin film with high efficiency and a precise composition gradient.

Means for Solving the Problems> The above objects of the present invention can be achieved by employing the following means. That is, it is a method of forming a thin film on the surface of a substrate by sputtering, in which multiple targets with different compositions are used and the substrate is moved during sputtering, so that the formed film is directed in the direction of its thickness and the composition is adjusted. A method of arbitrarily controlling the amount of sputtering, and a method of forming a thin film on the surface of a substrate by sputtering, in which the thin film is formed by using multiple targets with different components and changing the power applied to each target during sputtering. This is a method in which the composition of the film is arbitrarily controlled in the direction of its thickness, and furthermore, it is a method in which the substrate is moved during sputtering and the power applied to each target is varied.

Effect> During sputtering, the method of the present invention uses a plurality of targets and sequentially moves the substrate, or changes the applied power to each target, while the atmosphere remains constant without any change. Since a means for performing both simultaneously is adopted, the composition in the thin film can be arbitrarily changed in the direction of the film thickness.

That is, first, if we explain in detail the case of moving the base,
For example, if we consider sputtering a certain substrate using two targets: a target made of material A and a target made of material B placed a certain distance apart, if the substrate is near the target made of material A, then The thin film formed on the top surface of the substrate has a composition rich in substance A and low in substance B, and the opposite is true when the substrate is near the target of substance B. Therefore, when the substrate is moved from the target side of substance A to the target side of substance B at a certain constant speed, the composition of the thin film will have a distribution as shown in the graph shown in FIG. 1, for example. In Figure 1, the horizontal axis represents the position in the film thickness direction, where a is the thin film surface position formed when the substrate was closest to the target of substance A, and a is the position of the thin film surface formed when the substrate was closest to the target of substance B. It shows the position of the thin film surface formed when it was in position.

Next, to explain in detail the case of changing the applied power to a plurality of targets, for example, two targets, a target made of substance C and a target made of substance placed at a certain distance from each other, are applied to a certain base. Considering the case where sputtering is performed by placing both targets at the same distance from the substrate, first, the applied power to the material target is set to 0, and the applied power to the -old material C target is set to a sufficiently high value before sputtering. and
After that, the applied power to the material target is increased while decreasing the applied power to the material target, and finally, the applied power to the material target is raised sufficiently, and the applied power to the material target is reduced to 0. Then, the composition of the thin film has a distribution as shown in the graph shown in FIG. 2, for example. Second
In the figure, the horizontal axis represents the position in the film thickness direction, C is the thin film surface formed when sufficient power is applied only to the target of material C without applying it to the target of material C, and d is the surface of the thin film formed when sufficient power is applied only to the target of material C.
The figure shows the surface position of the thin film formed when sufficient power is applied only to the target material C without applying it to the target material C.

Note that FIGS. 1 and 2 above are examples when the moving speed of the base body is constant and the rate of increase/decrease of the applied power to both targets is constant. As shown in the figure, a straight line is obtained, but By changing the power increase/decrease rate stepwise or at a desired rate, the composition can also be changed stepwise or in a curved manner.

In addition, when considering the above explanation, it will be obvious that if the applied power is changed along with the movement of the substrate, a gradient composition film can be obtained more easily and precisely.

Note that the substances A, B, C, and D mentioned in the above description may be either pure metals or compounds.

In the case of compounds, they are decomposed into two atomic molecules during the subinterning process, and sometimes volatile substances or substances with high vapor pressure are generated, and these substances are not completely incorporated into the thin film. There may be a deficiency in a certain composition, and in such a case, a so-called reactive sputtering method may be used in which a gas containing the above-mentioned component that is likely to be depleted is mixed into the discharge gas.

<Example> Hereinafter, the present invention will be described in detail while showing examples thereof.

Using a semicircular graphite and silicon carbide target 1 with a diameter of 4 inches, a planar magnetron type high-frequency sputtering method is used to deposit a 3-thickness layer on the substrate 2.
A graded composition film of μ's was formed at room temperature. First, the substrate 2 is set on the graphite target side of the anode 4 of the vacuum chamber 3, and after the degree of vacuum in the vacuum chamber 3 reaches 5 x 10"7 Torr, argon gas is introduced to reduce the vacuum to 5 x 10 Torr.
I made it. Next, the main valve was gradually closed, and the gas pressure in the vacuum chamber 3 was set to 4×1 O −2 Torr. After bliss sputtering was performed for 20 minutes with the shutter closed at a high frequency power of 200 W, the high frequency power was increased to 400 W, the shutter was opened, and the substrate was moved toward the silicon carbide targen at a speed of 0.5 m/min. I did this spanta for 2 hours while doing this.

In order to confirm whether the composition of the formed thin film is inclined in the film thickness direction, we deposited a large number of small substrates on the anode as shown in Figure 3, and measured the thickness of these thin films. The composition was investigated using an X-ray photoelectron spectrometer (ESCA). The results are shown in FIG.

As is clear from FIG. 4, the composition of the produced thin film is continuously graded between the silicon carbide side and the graphite side of the target. Moreover, the hardness of those thin films is shown in FIG. It can be seen from FIG. 5 that as the composition becomes more gradient, the hardness also becomes more gradient.

Example 1: Using a high-frequency sputtering device equipped with two planar magnetron cathodes and capable of independently controlling high-frequency power, a 1 μm-thick composition-grading controlled film was formed on the substrate 2 at room temperature. The equipment used is shown in Figure 6. For target 1, graphite and silicon carbide each having a diameter of 3 inches were used.

First, the substrate is set on the anode 4 of the vacuum chamber, and the substrate is placed on the anode 4 of the vacuum chamber.
After the vacuum level reached 5 x 10 Torr, argon gas was introduced to make the vacuum level 5 x 10 Torr. Next, gradually close the main valve and increase the gas pressure in vacuum chamber 3 to 4X 1
It was set to O-2 Torr. After bliss sputtering was performed for 20 minutes with the shutter closed and the cathode power of graphite and silicon carbide set to 200 watts, respectively, the shutter was opened with the cathode power of graphite and silicon carbide set to 400 watts and 0 watts, respectively, and the substrate 2 was sputtered. 5 r,
Main sputtering was started while rotating at p and m. Main sputtering was performed for 8 hours while decreasing the graphite cathode power at a rate of 50 watts/hour and increasing the silicon carbide cathode power at the same rate. The cathode powers of graphite and silicon carbide immediately before the end of the main sputtering were 0 watts and 400 watts, respectively.

In order to confirm whether the composition of the produced thin film is inclined in the film thickness direction, the composition of the thin film produced with various cathode powers was examined by ESCA.

The results are shown in FIG. As is clear from Figure 7,
The composition of the produced thin film is graded corresponding to the respective cathode power ratios. In addition, the hardness of those thin films was
As shown in the figure. From FIG. 8, it can be seen that the hardness also gradients as the composition gradients.

<Effects of the Invention> As described above, according to the method of the present invention, the operation is simple, and since the sputtering method is adopted,
Since there is no need to heat the substrate, thin films can be formed on the surfaces of all kinds of materials, such as materials that decompose or change in quality at high temperatures, metals with low melting points, plastics, etc. Since there is no need to change the components of the atmospheric gas during sputtering, the plasma is stable and a thin film can be formed with high efficiency.

In addition, the composition of the obtained thin film can be arbitrarily changed in the film thickness direction in two continuous steps or in a curved manner by appropriately selecting the moving speed of the substrate and/or the rate of change in the power applied to the target. As a result, near the surface of the substrate, the composition is the same as that of the substrate, but as a result, near the substrate, the composition and coefficient of thermal expansion can be made equal to those of the substrate. The film has high adhesion and crack resistance, and the outermost layer is a thin film having desired physical properties including wear resistance.

Furthermore, since the method of the present invention uses a sputtering method, the thin film obtained is highly amorphous, and therefore has a unique function that is not found in a thin film produced by the CVD method, which has a high crystallinity.

[Brief explanation of the drawing]

Figures 1 and 2 are graphs for explaining the method of the present invention, Figure 3 is an explanatory diagram of the confirmation test conducted in Example 1, Figure 4 is a graph showing the results of Example 1, and Figure 5 is a graph showing the results of Example 1. The figure is a graph showing the hardness change of the thin film obtained in Example 1, Figure 6 is an explanatory diagram of the apparatus used in Example 2, Figure 7 is a graph showing the results of Example 2, and Figure 8 is a graph showing the results of Example 2. Graph showing changes in hardness of the thin film obtained in Example 2. In the figure l: Target 2: Substrate 3: Vacuum chamber 4: Anode

Claims (1)

[Claims] 1. A method of forming a thin film on the surface of a substrate by sputtering, using a plurality of targets with different components and moving the substrate during sputtering,
A method for forming a gradient composition control film, characterized in that the composition of the film to be formed is arbitrarily controlled in the film thickness direction. 2. Formation of a gradient composition control film in the method according to claim 1, characterized in that silicon carbide and carbon are used as targets, and the composition ratio of silicon and carbon is arbitrarily controlled in the film thickness direction. Law. 3. A method of forming a thin film on the surface of a substrate by sputtering, in which multiple targets with different components are used and the power applied to each target during sputtering is varied to control the thickness of the formed film. A method for forming a gradient composition control film characterized by arbitrarily controlling the composition in a direction. 4. Formation of a gradient composition control film in the method according to claim 3, characterized in that silicon carbide and carbon are used as targets, and the composition ratio of silicon and carbon is arbitrarily controlled in the film thickness direction. Law. 5. A method of forming a thin film on the surface of a substrate by sputtering, which uses multiple targets with different components, moves the substrate during sputtering, and changes the applied power to each target. A method for forming a film with a gradient composition, characterized in that the composition of the film is arbitrarily controlled in the film thickness direction. 6. Formation of a gradient composition control film in the method according to claim 5, characterized in that silicon carbide and carbon are used as targets, and the composition ratio of silicon and carbon is arbitrarily controlled in the film thickness direction. Law.