JPH036373A - Production of thin super-smoothed film - Google Patents

Abstract

PURPOSE:To smoothen the surface of a thin film at an atomic level by forming a thin film by irradiating a substrate with an assistant ion beam simultaneously with irradiating a target with a sputter ion beam and then irradiating the resulting thin film with the assistant ion beam. CONSTITUTION:A target 5 (carbon graphite) is set in a holder 4 in a vacuum vessel 1 and a substrate 3 is also set in a holder 2, and the pressure inside the vacuum vessel 1 is regulated to about 3X10<-6>Torr. Subsequently, the target 5 is irradiated with Ar ions by means of an ion gun 6 for sputtering, by which the substrate 3 is irradiated with carbon atoms. Simultaneously, the substrate 3 is irradiated with hydrogen ions by means of an assistant ion gun 7, by which a thin diamond film is formed on the substrate 3. Further, the resulting thin film is irradiated with helium ions from the assistant ion gun 7, and simultane ously, the substrate holder 2 is slowly turned at about 10-20rpm, by which irradi ation is carried out so that irradiation angle is regulated to about 60 deg.. By this method, the surface of the thin diamond film can be finished to the roughness of atomic level.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to smoothing of thin films formed by ion beam method.

(b) Conventional technology The ion beam method is a well-known technique for forming a thin film on a substrate, and in particular, as a method for forming a semiconductor thin film, for example, It is described in Publication No. 63-217655.

By the way, when trying to form a diamond thin film (graphitized carbon thin film) on a substrate, it is generally difficult to form this diamond thin film at low temperatures.
It is usually performed using a high temperature process such as CVD.

In addition, the diamond thin film formed in this way has a large surface unevenness, which is treated at the atomic level (
Even with techniques such as poly7ing, it is impossible to smooth the surface to a roughness of 1 nm or less (approximately 10 nm at most).
It is.

Furthermore, even when surface finishing a thin film at this level, the thin film must be removed from the forming apparatus, which is very time consuming.

(c) Problems to be Solved by the Invention The problems to be solved by the present invention are to form a thin film such as a diamond thin film, which is difficult to form at low temperatures, at a low temperature using an ion beam method, and at the same time to improve the surface of the thin film at an atomic level. It is to smooth.

(d) Means for Solving the Problem A substrate and a target, an assist ion gun provided opposite to the substrate, and a sputtering ion gun provided opposite to the target are arranged in a vacuum state. , simultaneously irradiating constituent atoms of the target onto the substrate with an ion beam irradiated from the sputtering ion gun, forming a thin film on the substrate with the ion beam irradiating from the assist ion gun, and further applying a thin film to the formed thin film. A ion beam is irradiated from the assist ion gun to smooth the thin film.

(e) Operation A series of sea fences can perform everything from forming a thin film to smoothing the surface while the substrate remains inside a vacuum container or the like.

(f) Example The method for producing an ultra-smoothed thin film of the present invention will be explained in detail below with reference to an example of the drawings.

FIG. 1 is a side view showing a thin film forming apparatus, in which (1) is a vacuum container that can maintain a high vacuum state of about 3 x 10-' Torr, and (2) is a vacuum container that is placed inside the container (1). A substrate holder (4) holds the substrate (3) on which the thin film is to be formed, and (4) is a target (5) (graphitized carbon) which is also placed approximately in the center of the container and becomes the constituent atoms of the thin film. Target holder, which holds (
6) is an ion gun for sputtering that is provided on the - side of the container (1) in opposition to the target (5) and irradiates the target (5) with argon ions (Ar") to sputter the target (5). , (7) are provided on the other side of the container (1) facing the substrate (3), and the substrate (3)
This is an assist ion gun that irradiates helium ions (He+) to form a thin film on.

Here, the substrate holder (2) can be heated and cooled, and the assist ion gun (7) adjusts the irradiation angle of the helium ions (He'') irradiated from here to the substrate (3) to 0° (vertical). The angle can be set arbitrarily from the angle of incidence to 90° (60' is preferred), and can also rotate within the same angular range.

Next, the formation of a thin film will be explained using the formation of a diamond thin film as an example.

First, carbon graphite is used as a target (5) and set in a target holder (4).

Further, the substrate (3) is set in the substrate holder (2), and the inside of the vacuum container (1) is brought into a high vacuum state of about 3×10-' Torr.

Next, the beam voltage of the sputtering ion gun (6) is set to several hundreds of volts to several kV, and the beam current of one of the sputtering guns is set to about several tens of mA and started, and argon ions are applied to the target 7) (5). By irradiating, carbon atoms are irradiated onto the substrate (2).

At this time, hydrogen ions (H+) are simultaneously irradiated from the assist ion gun (7) to form a diamond thin film on the substrate (3). Note that the hydrogen ion energy of the assist ion gun (7) is preferably about 50 to 200 eV.

Now, it is difficult to say that the diamond thin film thus formed has an ultra-smooth surface due to changes in the ion beam current density distribution, etc.

Therefore, next, using the assist ion gun (7) again,
The previously formed diamond thin film will be ultra-smoothed. Note that it is not necessary to take out the substrate (3) when moving from the above step to this step.

In this process, helium ions (H
e+) is used. Then, the substrate holder (2) is
While rotating slowly at ~20 rpm, the irradiation angle from the assist ion gun (7) to the substrate (5) was set to 6.
The helium ions are irradiated at about 0°.

By the way, in the smoothing step, the beam voltage of the assist ion gun (7) is gradually decreased as the processing time increases, and as shown in Fig. 2, the irradiated helium ion energy is adjusted as the processing time progresses. Accordingly, the surface smoothing process is performed by gradually changing the direction of decrease.

Finally, the helium ions from the assist ion gun (7) are reduced to the minimum energy value necessary to reach the substrate (3), and a smoothing process is performed for about 30 minutes.

In the smoothing process, the energy of the first helium ion is large as shown in FIG. 2, and therefore several carbon atoms on the surface layer of the diamond thin film on the substrate (3) are repelled. When this helium ion energy is decreased with processing time, the number of carbon atoms that one helium ion repels gradually decreases.

Eventually, when the energy reaches the minimum required to reach the substrate (3), one carbon atom is taken away from the surface layer of the diamond thin film by the interaction force with the helium ions, resulting in the thin film becoming rough on the atomic level. It can be finished with

FIG. 3 shows the relationship between processing time (about 30 to 40 minutes is sufficient) and surface roughness of a diamond thin film formed by the method described above. In the same figure (A), unevenness is seen in the range of + and -50 people from the reference surface (0) because it is not smoothed, whereas in (B), the helium ion irradiation by the assist ion gun (7) As a result of processing for 1 hour, a substantially uniform surface was obtained.

(G) Effects of the Invention As described above, the present invention enables the formation of thin films and ultra-smoothing with the same device, which improves productivity during thin film formation, and also makes it possible to use ions as an atomic tool. By changing the beam voltage, that is, the ion energy used for smoothing, the surface of thin films can be smoothed at the atomic level, making it possible to smooth the surface of thin films at the atomic level. This will greatly contribute to the application of this technology.

[Brief explanation of the drawing]

Figure 1 is a side view showing the thin film manufacturing apparatus of the present invention, Figure 2 is a diagram showing changes in helium ion energy from the assist ion gun with respect to smoothing time, and Figure 3 (A) is when smoothing is not performed. A diagram showing the surface roughness of a thin film of
(B) is a diagram showing the surface roughness of the thin film after smoothing for 1 hour. (1) Vacuum vessel, (3) Substrate, (5) Target, (7) Assist ion gun, (6) Sputtering ion gun.

Claims (1)

[Claims] (1) Under a vacuum condition, a substrate and a target, an assist ion gun provided opposite to the substrate, and a sputtering ion gun provided opposite to the target;
and irradiating constituent atoms of the target onto the substrate with an ion beam irradiated from the sputtering ion gun, and at the same time forming a thin film on the substrate with the ion beam irradiated from the assist ion gun, further forming a thin film. A method for producing an ultra-smoothed thin film, which comprises smoothing the thin film by irradiating the thin film with an ion beam from the assist ion gun.