JPH0261060A - How to generate thin films - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for producing a thin film of a desired material on a substrate, and more particularly to a method for producing a thin film of a desired material on a substrate, and more particularly, a method for producing a thin film of a desired material on a substrate, and more particularly, a method for producing a target sputtered out with an ionized inert gas in the physical vapor deposition method. The present invention relates to a method for producing a thin film in which components of the above are produced on the surface of a substrate.

Conventional technology Thin film production technology using physical or chemical vapor deposition methods is used in many industrial fields, mainly in the semiconductor field.
The desired properties (purity) of the produced thin film.

Various methods have been developed and put into practical use to provide crystallinity (crystallinity, etc.).

Under these circumstances, the sputtering method has been put into practical use as a biofilm method that produces denser films than the vacuum evaporation method, but among these methods, the ion beam sputtering method (IBD method) is: ■ Sputtering in a high vacuum As a result, a highly pure film can be obtained with less atmospheric gas mixed into the produced film.

(2) Since the substrate is located outside the plasma region where gas is ionized, the temperature rise of the substrate is small, making it possible to form a thin film on a substrate made of a low melting point material.

It has been put into practical use as a method with the following characteristics.

In general, the ion beam sputtering method, as shown in Figure 1,
It consists of an ion gun that generates an ion beam, a generation chamber where a substrate is placed, and an exhaust system. They are geometrically arranged so that an accelerated ion beam (usually human ions) generated by an ion gun collides with the target, and sputtered target material adheres to the substrate surface.

In this type of ion beam sputtering method, the ion beam irradiated onto the target is electrically or magnetically focused and irradiated onto the target, but the generated ions are electrically accelerated on a grid. The intensity of the beam has a distribution as shown in FIG. 2, and is not completely concentrated onto the target, but is dispersed with a certain probability. On the other hand, in order to increase the purity of the produced film when producing thin films, materials with low sputtering efficiency are used as constituent materials around the target, but the effect is not sufficient and some of the produced films do not contain the target. Surrounding constituent materials were contained as impurities. In order to prevent the contamination of such impurities and produce a highly pure film, it is possible to solve the problem by using a target that is sufficiently large for the diameter of the ion gun, but the area for attaching the target in the vacuum container is limited. In addition, the price of the target has become expensive, and there are technological limits to the size of the target, making it difficult to produce a film of sufficiently high purity.

Problems to be Solved by the Invention The present invention, in the above-mentioned thin film production method, prevents components other than the target material from being mixed into the thin film, and stably produces a thin film on a substrate with a composition close to the target purity. The purpose is to

Means for Solving the Problems In order to solve the above problems, the present invention selects and introduces a gas that does not react with the target or substrate into a vacuum atmosphere.

In active ion beam sputtering, when a reactive gas is introduced and a sputtered target material is reacted with the gas to form a film, the surface of the target preferentially reacts with the gas due to ion bombardment, resulting in a slow production rate. However, when producing a reactive film using ion beam sputtering, a second gun is used to irradiate the surface of the substrate with ions from the reacting gas. Efforts have been made to avoid mixing reactive gases.

The present invention makes use of such a conventional phenomenon, and by introducing a gas into the atmosphere that does not affect the target or substrate material, the sputtering rate of the material surrounding the target is reduced by ion irradiation. This improves the purity of the produced film by reducing the purity of the produced film and preventing the contamination of peripheral materials into the produced film.

EXAMPLES Hereinafter, the present invention will be explained in detail using examples together with drawings.

(Example) A gold target 16 with a diameter of 3 inches and a purity of 3-H was placed in the ion beam sputtering apparatus shown in FIG.
i) and set it in a target holder made by 10' (Tor
After evacuation up to r), the human r gas is introduced into the ion gun 11.
After generating a human ion beam by maintaining the gas pressure in the generation chamber 12 at x10' (Torr), oxygen gas is introduced and
A gold film with a thickness of 1 μm is formed on the surface of a quartz substrate 170 heated to 50° C. In FIG. 1, 11 is an ion gun, 12 is a generation chamber, 13 is an exhaust path, 14 is a murine gas introduction valve, 15 is active gas introduction pulp, 16 is a target, and 17 is a quartz substrate. Further, FIG. 2 shows the relationship between the distance from the beam axis of the sputtering apparatus shown in FIG. 1 and the ion beam intensity ratio.

(Comparative Example-1) A titanium (Ti) gold target with a diameter of 3 inches and a purity of 3-H was placed in the ion beam sputtering apparatus shown in Figure 1.
Place it in a target holder manufactured by Tor
After evacuation to r), introduce mur gas into the ion gun and 1x1
A uniform ion beam is generated while maintaining the gas pressure in the generation chamber at o-' (Torr) to form a 1 μm thick gold film on the surface of a quartz substrate heated to 260°C.

(Comparative Example-2) A titanium (Ti) target with a diameter of 5 inches and a purity of 3 to N was placed in the ion beam sputtering apparatus shown in Figure 1.
) and set it in a target holder made of 10' (To
After exhausting to rr), introduce Ar gas into the ion gun and
A 1 μm thick gold film is generated on the surface of a quartz substrate heated to 250° C. by generating a uniform ion beam while maintaining the gas pressure in the generation chamber at 10 Torr.

Among the impurities contained in the films produced under the conditions of Examples and Comparative Examples, the content of Ti, which is the material of the target holder, was investigated by mass spectrometry. As a result, as shown in Table 1, the films formed according to the present invention In the example, the intensity ratio of Ti ions to gold ions is lower (it can be seen that less Ti is mixed in) than in Comparative Example-1 and Comparative Example-2, which are conventional methods.

Furthermore, when the electrical resistance of the produced film is measured using the four-terminal method,
As shown in FIG. 3, the gold film produced in the example is the comparative example
1. Compared to the gold film according to Comparative Example 2, the specific resistance is lower and a value close to that of the bulk material is obtained.

Table 1: Amount of impurities in the produced film (Ti intensity ratio = (Ti+)/(MuU+)) Effects of the invention As described above, the present invention reduces the amount of impurities when forming a film on a substrate using the sputtering phenomenon. It becomes possible to prevent contamination and to stably maintain the purity of the produced film. Furthermore, according to the present invention, it is possible to generate a highly pure film regardless of the degree of focusing of the ion beam, so it is possible to maintain the purity of the generated film even with a target having a small diameter, reducing target costs. This makes it possible to improve usage efficiency.

Furthermore, according to the present invention, it is possible to achieve high purity of the produced film without improving the constituent materials of the device or the shape of the ion gun, and it is also highly resistant to changes in the ion beam profile due to changes over time during device operation. This makes it possible to stably maintain the purity of the produced film.

In the present invention, the effect has been explained using an example in which gold is used as the film and ion beam sputtering is used as the production method, but this effect is also applicable to other chemically stable materials such as platinum in addition to gold. It is also possible to obtain the same effect. However, the same effect can be obtained by a sputtering method in which a target and a substrate are placed in a plasma region.

Furthermore, although the present invention has been explained in detail with reference to an example in which oxygen gas is used as the gas to be introduced, the same effect can be obtained even if the gas to be introduced is nitrogen gas or air (mixed gas of oxygen and nitrogen). It will be done.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a thin film production apparatus for carrying out the method of the present invention, Fig. 2 is a characteristic diagram showing the ion beam profile, and Fig. 3 is a ratio of the produced films obtained by the present invention and the conventional technology. FIG. 3 is a characteristic diagram showing a comparison of resistances. 11. Ion gun, 12... Generation chamber, 1
3...Exhaust route, 14...Mur gas introduction valve, 16...Active gas introduction pulp, 16
...Target, 17...Quartz substrate. Name of agent: Patent attorney Shigetaka Awano and one other person

Claims (2)

[Claims] (1) When producing a thin film using a sputtering phenomenon in a reduced pressure atmosphere, there is a gas in the atmosphere that does not react with the target material or the substrate, but reacts with the materials constituting other parts by assisting with ion bombardment. A method for producing a thin film characterized by selection and introduction. (2) The method for producing a thin film according to claim 1, wherein the target material is gold or platinum, and the gas introduced into the atmosphere is oxygen, nitrogen, or a mixture of both.