JPH0633235A - Formation of protective film - Google Patents

Abstract

PURPOSE:To provide a method for forming a protective film which is sufficiently provided with a function as a protective film excellent is resistance to oxidation. etc., and is easily removable while suppressing damage to the treated surface of a substrate to minimum. CONSTITUTION:First, the protective film 16 is formed on the treated surface of the substrate 14 by a vacuum deposition method using an evaporating source 6. Then, he ions 12 drawn from an ion source 10 are injected into the protective film so as to make the intruding depth thereof smaller than the film thickness of the protective thickness 16. Damage given to the treated surface of the substrate is thus suppressed to the minimum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protective film for forming a protective film on a treated surface of a substrate which has been subjected to treatment such as film formation under vacuum, to prevent the treated surface from being exposed to the atmosphere. It relates to a forming method.

[0002]

BACKGROUND ART As a method for forming a film on a substrate, there are typically a CVD method (chemical vapor phase method) and a PVD method (physical vapor phase method). Each has its own characteristics.

Generally, the CVD method has a high film deposition rate and good throwing power. However, since the film is formed while heating the substrate, the type of substrate is limited. Also,
It is undeniable that the substrate will be damaged when exposed to high temperatures.

On the other hand, the vacuum vapor deposition method, which is a type of PVD method, can form a film without exposing the substrate to a high temperature, so that the type of the substrate is not limited, but the adhesion of the film is inferior to the CVD method.

Therefore, these film forming methods are properly used according to the type of the substrate, the purpose of the film to be attached, and the like.

When a plurality of film forming processes are combined to form a film, for example, a multi-layer film on a substrate, it may be necessary to use a plurality of film forming apparatuses. In that case, the treated substrate must be exposed to the atmosphere when finishing the previous treatment step and moving to the next treatment step. At this time, the treated surface of the substrate (that is, the surface of the film if the substrate is subjected to a film-forming treatment) is exposed to the atmosphere and is oxidized, contaminated, or corroded, whereby the treated surface or its There is a risk of adversely affecting the properties of the film formed in the next step.

Therefore, in order to avoid this, when forming, for example, a multilayer film on a substrate using a plurality of film forming apparatuses, the substrate is exposed to the atmosphere when moving from the previous film forming step to the next film forming step. However, the same applicant has separately proposed a method of forming a protective film so that the treated surface is not oxidized, contaminated, or corroded.

That is, the protective film is formed on the surface of the substrate (more specifically, the film formed thereon) which has been treated in the previous step without exposing the substrate to the atmosphere in the same film forming apparatus. To form. After that, in the film forming apparatus for performing the next step, before performing the next film forming step, the protective film is removed and the target step is started. Through such a process, even if the substrate is once exposed to the atmosphere, the treated surface of the substrate is not oxidized, contaminated or corroded.

[0009]

The protective film has so far been formed mainly by the sputtering method or the vacuum deposition method.

However, when the above-mentioned protective film is formed by the sputtering method, the energy of sputtered particles is large and it is difficult to control the energy, so that the treated surface of the substrate is easily damaged. Further, since the energy of the sputtered particles is large, the adhesion between the treated surface of the substrate and the protective film is large, and therefore it is difficult to remove the protective film without damaging the treated surface of the substrate as much as possible.

On the other hand, in the vacuum vapor deposition method, the energy of vapor deposition particles is small, damage to the treated surface of the substrate is minimized, and the protective film can be easily removed. However, this method makes it difficult to form a dense protective film. Therefore, the oxidation resistance of the protective film is poor.

Therefore, the present invention forms a protective film which has a sufficient function as a protective film such as excellent oxidation resistance while minimizing damage to the treated surface of the substrate, and which is easy to remove. The main purpose is to provide a method capable of doing so.

[0013]

In order to achieve the above object, the method of forming a protective film according to the present invention is such that the protective film as described above is first formed by a vacuum vapor deposition method, and then an ion is added to the protective film. The feature is that the ion implantation is performed such that the penetration depth is smaller than the film thickness of the protective film.

[0014]

According to the above method, since the protective film is formed by the vacuum evaporation method, the damage given to the treated surface of the substrate can be minimized.

Further, after forming the protective film by the vacuum deposition method,
Since the ion implantation is performed in the protective film, the protective film becomes dense due to the packing action of the vapor deposition atoms by the ions, and the invasion / diffusion of oxygen from the surface layer of the protective film to the inside is suppressed,
A film having a sufficient function as a protective film can be obtained.

Further, since the penetration depth of ions is made smaller than the film thickness of the protective film, it is possible to prevent mixing due to ions at the interface between the protective film and the treated surface of the substrate,
Therefore, removal of the protective film is easy.

[0017]

FIG. 1 is a sectional view showing an example of a film forming apparatus for carrying out the method of forming a protective film according to the present invention. This apparatus includes a vacuum container 2 that is evacuated by a vacuum exhaust device (not shown), and a substrate 14 housed in the vacuum container 2.
An evaporation source 6 that forms a protective film 16 by vapor-depositing an evaporation substance 8 on the substrate, and an ion source 10 that irradiates the substrate 14 with ions 12. Inside the vacuum container 2, a holder 4 that holds the base 14 is provided.

Using such an apparatus, the protective film 16 is formed on the treated surface of the substrate 14 as follows. That is, first, the evaporation source 6 is operated to evaporate a desired evaporation substance (eg, silicon, metal, etc.) 8 for forming a protective film from the evaporation source 6, and this is evaporated on the treated surface of the substrate 14, and such a vacuum evaporation is performed. By the method, the protective film 16 having a desired film thickness is formed on the treated surface of the substrate 14.

Next, desired ions (for example, inert gas ions such as argon, nitrogen ions,
(Oxygen ions, etc.) 12 are extracted and injected into the protective film 16 formed as described above to perform ion injection.

At the time of the ion implantation, referring to FIG. 2, the penetration depth (also referred to as a projection range) R _P of the ions 12 is made smaller than the film thickness d of the protective film 16. This is because when the penetration depth R _P of the ions 12 becomes larger than this, the ions 12 reach the treated surface of the substrate 14 over the protective film 16, and then the mixing action of the ions 12 causes the protective film 16 to be processed. At the interface between the protective film 16 and the treated surface of the substrate 14, a mixed layer composed of the substances that form the treated surface of the protective film 16 and the substrate 14 is formed, and this acts like a wedge to increase the adhesion strength of the protective film 16. This is because not only the removal of the protective film 16 becomes difficult, but also the treated surface of the substrate 14 is damaged by the implanted ions 12.

Next, more specific examples according to the present invention and comparative examples for comparison therewith will be described.

(Example) On a Cu film (which is the treated surface in this case) formed on the surface of a substrate, Si was formed as a protective film by a vacuum deposition method to a film thickness of 300 Å, and then this protective film was formed. Ar ions were implanted into the film at an energy of 2 KeV at 1 × 10 ¹⁵ ions / cm ² . The ion penetration depth at this time is about 150 Å.

(Comparative Example) Si was formed as a protective film on the same Cu film as described above to a film thickness of 300 Å by a vacuum deposition method, but subsequent ion implantation was not performed.

(Evaluation) The samples of the above-mentioned Examples and Comparative Examples were both left in the atmosphere for one week, and thereafter, component analysis in the depth direction was carried out by Auger electron spectroscopy. The results are shown in FIG. 3 (Example) and FIG. 4 (Comparative example). In both figures, the sputtering time on the horizontal axis corresponds to the depth direction from the surface.

As can be seen from FIG. 3, the samples of the examples are
Oxygen (O) was detected only on the surface of the Si film, which is a protective film, and was not diffused into the Cu film. On the other hand, FIG.
As can be seen from the above, the sample of the comparative example has a protective film of Si.
Oxygen is detected not only on the surface of the film but also in the film, and C
It can be seen that it reaches the interface with the u film. From this, it can be seen that the Si film of the example sufficiently functions as a protective film, but the Si film of the comparative example does not function as a protective film.

Further, in the embodiment, it takes a longer time to sputter the Si film because of the ion implantation.
This is an indication that the film is dense.

[0027]

As described above, according to the present invention, since the protective film is formed by the vacuum vapor deposition method, it is possible to minimize damage to the treated surface of the substrate.

Further, after the protective film is formed, the surface of the protective film is ion-implanted, so that the protective film becomes dense, and the penetration and diffusion of oxygen from the surface layer to the inside is suppressed. The one with sufficient function is obtained.

Further, since the depth of penetration of ions is made smaller than the film thickness of the protective film, it is possible to prevent mixing by ions at the interface between the protective film and the treated surface of the substrate,
Therefore, removal of the protective film is easy.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a film forming apparatus for carrying out a method of forming a protective film according to the present invention.

FIG. 2 is an enlarged cross-sectional view of a substrate and a protective film on its surface.

FIG. 3 is a diagram showing the results of component analysis in the depth direction by Auger electron spectroscopy for samples of Examples.

FIG. 4 is a diagram showing the results of component analysis in the depth direction by Auger electron spectroscopy for the sample of the comparative example.

[Explanation of symbols]

 2 vacuum container 6 evaporation source 8 evaporation material 10 ion source 12 ions 14 substrate 16 protective film

Claims (1)

[Claims] 1. A method of forming a protective film on a treated surface of a substrate that has been subjected to treatment under vacuum, which prevents the treated surface from being exposed to the atmosphere. First, the protective film is formed by a vacuum vapor deposition method. Then, a method for forming a protective film is characterized in that ion implantation is performed in the protective film such that the depth of penetration of ions is smaller than the film thickness of the protective film.