JPH03162571A - Formation of thin film by reactive sputtering in opposed target type sputtering method - Google Patents

Abstract

PURPOSE:To efficiently form a thin film having a desired compsn. without receiving damages by introducing gaseous Ar into the space part between targets disposed to face each other to form plasma and bringing the target atoms into reaction with a separately introduced reactive gas. CONSTITUTION:A voltage is impressed between a pair of the targets 3, 3 disposed to face each other in a vacuum vessel 1 and the gaseous Ar is introduced from an introducing port 8 facing the space part 5 between both into this space part. The plasma space is formed in the above-mentioned space part 5 in such a manner and the target atoms are splashed by sputtering the targets 3. The plasma is introduced onto substrates 7 disposed alongside the above-mentioned space part 5. Further, the reactive gas, such as 02, is supplied from the introducing port 9 disposed alongside the substrates 7. This reactive gas is brought into reaction with the target atoms in the plasma on the front surface of the substrate 7. Thus, the thin film having the desired compsn. is adequately and efficiently formed without receiving the damage of the plasma, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is applicable to Si02, S!, which is used as a protection film for a magnetic thin film of a magneto-optical disk, for example. J<, Ah(h,
The present invention relates to a method for forming a single film by reactive sputtering in a facing target sputtering method suitable for forming thin films of metal oxides such as AN, metal nitrides, etc.

(Prior Art) Conventionally, as a means for forming a thin film by reactive sputtering, as shown in FIG. There is a method for sputtering the targets 3el to 3e while introducing a mixed gas of a gas and a reactive gas (for example, a mixed gas of Ar and O.) or only a reactive gas alone.

Furthermore, a reactive sputtering method different from the above-mentioned method has been proposed in Japanese Patent Application Laid-Open No. 63-76868.

Such means uses a magnetron sputtering device, and as shown in FIG. 4, the argon gas Ar and the reactive gas 02 are introduced into the vacuum chamber lf in which the target 3f and the substrate 7f are arranged through separate introduction ports 20. This is to be done from 21 onwards. Conventionally, after the argon gas and the reactive gas are simultaneously introduced into the vacuum chamber 1f, the target 3 is
f sputtering was performed.

(Problem to be Solved by the Invention) However, in the former conventional means shown in FIG. 3, sputtering is started by introducing a reactive gas or a mixed gas of a reactive gas and argon gas into the vacuum chamber 1e. Therefore, when a plasma space is formed in the space 5e between the targets, the surface of the targets 3e+3e reacts with the reactive gas, causing a phenomenon in which an insulating film or an oxide film is generated and adhered to the target surface. However, if an insulating film is attached to the target surface in this way, there is a problem in that target sputtering using a DC power source becomes difficult.

In order to solve this problem, a high frequency power source (R
However, when using the RF power source, the two points i! This shows a tendency for the plasma space to expand to the area A shown by the # line. Therefore, if an RF power source is used, the substrate surface will be damaged by the plasma that protrudes outside the space 5e, making it unsuitable for forming a high-quality thin film.

Furthermore, even if oxides other than insulators are attached to the target surface, the composition of the thin film deposited on the substrate surface will also change due to changes in these substances attached to the target surface. produce a phenomenon.

Therefore, conventional methods have had the problem that it is difficult to form a thin film with a desired composition on a substrate.

On the other hand, in the latter conventional means shown in FIG. 4, although the introduction positions for argon gas and reactive gas are provided separately, they are placed in the vicinity of the target 3f at the start of the sputtering operation, as in the former means. Since both the argon gas and the reactive gas coexist, an insulating film and an oxide film are formed and adhered to the surface of the target to be sputtered. Furthermore, although the phenomenon of adhesion of insulating films, etc. should stop at the initial stage of sputtering work, in reality, the oxide film, etc. adhering to the target surface is sputtered and exists as ions in the plasma space. This attracts the reactive gas introduced into the substrate If side to the plasma space side, resulting in a phenomenon in which the reactive gas continues to enter the plasma space.

Therefore, even with the latter method, the efficiency of the sputtering operation is poor like the former method, and the composition of the thin film formed on the surface of the substrate is not constant due to the influence of the reactive gas in the plasma space. The composition makes it difficult to form a thin film.

Furthermore, in the latter method using a magnetron sputtering device, in order to cause the reactive gas to react appropriately with the scattered atoms of the target, a special device for ionizing the reactive gas is required, or a substrate Since 7f is directly exposed to plasma, it is disadvantageous compared to the former facing target sputtering method in terms of forming a thin film with good film quality and little damage.

Therefore, the present invention allows a desired thin film structure to be damaged by plasma or the like without causing undue changes in the thin film structure formed on the substrate surface by reacting a reactive gas with the target surface. The purpose of this is to properly and efficiently make a difference without any problems.

(Means for solving the problem) The present invention utilizes a facing target sputtering method, and
Rather than introducing the reactive gas into the vacuum chamber at the start of sputtering as in the conventional methods described above, the reactive gas is introduced into the vacuum chamber after forming a plasma space in the space between the targets. We have attempted to solve the above conventional problems by adopting a completely new method that does not exist in the past, which is to introduce a reactive gas into the plasma space and prevent it from having any adverse effects on the plasma space and the target surface. do.

That is, in the present invention, under conditions in which argon gas is introduced into a vacuum chamber 1 in which a pair of targets 3, 3 are provided facing each other, and no reactive gas is introduced, the targets 3,
After forming a plasma space in which target atoms are scattered in the space 5 between the targets by applying a voltage to 3, a reactive gas is separately introduced into the vacuum chamber 1, and the side of the space 5 between the targets is This is a method of forming a thin film by reactive sputtering in the facing target sputtering method, in which reactive gas is reacted with target atoms deposited on the substrate 7 placed on the opposite side at a position outside the plasma space.

Further, in the above structure, the present invention introduces argon gas through a gas inlet 8 provided facing the space 5 between the targets.
In addition, the reactive gas is introduced along the surface of the substrate from a gas introduction port 9 provided on the side of the position where the substrate 7 is disposed.

(Function) In the thin film forming method characterized by the above-mentioned horizontal holes, the plasma space is formed in the inter-target space 5 in an argon gas atmosphere in which no reactive gas is present, and then the vacuum chamber 1 is A thin film of a desired material can be formed by reacting the reactive gas introduced into the substrate with target atoms attached to the substrate surface.

Since the plasma space formed in the inter-target space 5 is formed in an atmosphere of only argon gas, there is a reactive gas that attracts the reactive gas introduced later into the plasma space. Gas ions are not mixed. Therefore, even if a reactive gas is introduced into the vacuum chamber 1 after forming a plasma space in the inter-target space 5, a phenomenon in which the reactive gas is actively attracted into the plasma space is unlikely to occur. becomes.

As a result, there is no possibility that reactive gas ions will enter the plasma space and a reactive gas compound (oxide film, insulating film, etc.) will be deposited on the target surface. Therefore, there is no possibility that the composition of the thin film on the substrate surface will change unduly due to changes in these compounds. Since the target atoms scattered by sputtering only react with the reactive gas in the region outside the plasma space, it is possible to form a thin film of stable material and structure.

Additionally, by eliminating the risk of an insulating film being deposited on the target surface, there is no need to use a high frequency power source for target sputtering, and appropriate sputtering can be continued even with a DC power source. Become.

Furthermore, since the reactive gas does not easily enter the plasma space of the inter-target space 5, the target can be sputtered and eroded at high speed by the 7Rgon ions, increasing the speed of film formation on the substrate surface. Can be done.

Further, the latter argon gas is introduced through a gas introduction port 8 provided facing the space 5 between the targets, and the reactive gas is introduced through a gas introduction port 9 provided on the side of the placement position of the substrate 7. In the method of introducing along the substrate surface,
This makes it possible to efficiently cause the argon gas to react with the sputtering force of the target and the reactive gas with the scattered atoms of the target.

(Example) Examples of the present invention will be described below.

This embodiment will be described by taking as an example a case where a thin film of aluminum oxide (A1203) is formed.

First, on the birch shown in FIG.
In the initial state in which the vacuum chambers 1 and 1 are mounted facing each other, the inside of the vacuum chamber 1 is evacuated from the exhaust port 4 to achieve a predetermined low pressure condition. Thereafter, only argon gas is introduced from the inlet 8 provided facing the space 5 between the targets 3.3, the argon gas pressure is set to, for example, 5 mTorr, and a negative pressure is applied to the target 3.3. Apply voltage. Board 7
may be placed in advance on the side of the inter-target space 5 by being supported by a holder 13 or the like.

Under such sputtering conditions, a plasma space in which 7luminium ions, gamma electrons, and argon ions as target atoms are mixed is formed in the inter-target space 5 where a perpendicular magnetic field is formed by the magnets 6 . Since no reactive gas is introduced into the vacuum chamber 1 at the initial stage of forming the plasma space, there is naturally no risk of an oxide film forming or adhering to the target surface.

Next, after confirming that the plasma space has been formed, oxygen as a reactive gas is introduced into the vacuum chamber 1 for the first time. Note that the introduction of the argon gas is continued. Oxygen may be introduced to the surface of the substrate 7 through an inlet 9 provided on the side of the substrate 7.

As a result, the inter-target space 5 is formed by sputtering.
The aluminum atoms (ions) that reach the surface of the substrate 7 and are deposited thereon are oxidized and formed as aluminum oxide on the surface of the substrate 7.

Since the oxygen discharged from the inlet 9 is supplied along the surface side of the substrate 7, even if the amount of oxygen supplied is small, it reacts accurately with the aluminum atoms, and a thin film of aluminum oxide is reliably formed. be decapitated.

Since the plasma space formed in the inter-target space 5 is formed only in an argon gas atmosphere, oxygen present outside the plasma space is attracted into the plasma space. Oxygen ions are not present. Therefore, the phenomenon in which oxygen introduced from the inlet 9 actively enters the plasma space and an oxide film is formed on the target surface is extremely unlikely to occur.

As a result, the targets 3, 3 are efficiently sputtered and eroded by the plasma mainly composed of 7 irgon ions containing oxygen, and the film deposition rate becomes high. In addition, since the oxidation of 7-aluminium is only carried out at a certain stage from the plasma space region to the time when aluminum is formed on the surface of the substrate 7, the oxidation reaction is stable and the quality of the thin film formed is stable. This makes it possible to keep the composition constant.

The inventor of the present invention conducted an experiment to form a thin film of hepta-luminium oxide similar to the above example, and obtained the following results.

Target material: aluminum (purity 99.99%)
Target size: 100 mm x 100 mm Distance between targets: 140 mm Distance from target center to substrate: 130 mm Argon gas pressure: 5 mTorr (flow rate 20 secM)
Oxygen gas flow rate: 15secM? Sputtering input power: l, 5kw (voltage 470V, discharge current 3.5A) In sputtering work under the above conditions, the deposition rate was 800A/
A thin film of 7 aluminum oxide (AI 03) was obtained by min. Furthermore, the same results were obtained when the argon flow rate was set to 4QsccM.

In the conventional method shown in FIG. 3, the desired AI203 could not be obtained unless the flow rate ratio of argon and oxygen was 1:1 or more, but in the present invention, the desired aluminum oxide could be obtained at a lower ratio as described above. Obtained.

This is because oxygen does not enter the plasma space in the inter-target space and the target is sputtered exclusively by 7-Rgon ions.

Incidentally, in the above embodiment, the film-forming operation of hepta-luminium oxide was explained as an example, but the specific material of the thin film formed in the present invention is by no means limited to this.

Therefore, the types of targets and reactive gases are not limited to 7-luminium or oxygen, and can be applied to various other types of thin film forming operations.

Further, in the present invention according to claim 1, it is not necessary to provide separate introduction ports for argon gas and reactive gas, or to provide reactive gas on the side of the substrate 7. .

For example, as shown in FIG. 2, the argon gas Ar and the reactive gas 02 may share the inlet 10, and
The timing of starting supply of reactive gas 02 may be delayed from the timing of starting supply of argon gas Ar by the operation. In such cases, 0 reactive gas. Since the reactive gas is not directly supplied to the surface of the substrate 7, the reaction efficiency of the reactive gas against the target scattered atoms is reduced, but the reactive gas still reacts with the target atoms in the area outside the inter-target space 5. This allows the work of forming a thin film of a desired material to be performed appropriately. In the present invention according to claim 1, the specific position, number, etc. of the gas introduction ports are never specified.

Furthermore, in the present invention, the specific sputtering work conditions and the specific configuration of the equipment used are not limited as in the above embodiments.
All of the working steps of the present invention may be modified within the intended scope of the present invention.

(Effects of the Invention) As described above, the present invention involves forming a plasma space in advance in the inter-target space in an atmosphere of only argon gas without introducing any reactive gas, and then introducing the reactive gas into a vacuum chamber. By introducing the reactive gas into the vacuum chamber, it is possible to obtain a thin film of the desired material by reacting the reactive gas with the target atoms. In this way, reactive gas ions are not mixed in the plasma space formed in the space between targets, so oxide films and insulating films are not formed or adhered to the target surface, or reactive gases introduced afterwards This makes it possible to appropriately eliminate the phenomenon in which particles are unduly attracted into the plasma space.

As a result, in the present invention, the material and composition of the thin film formed on the substrate surface are not unduly changed due to the oxide film, insulating film, etc. that adheres to the target surface, unlike conventional methods, and the desired material and composition can be changed. This has the special effect of allowing the thin film formation work of the assembly to be carried out appropriately.

In addition, by eliminating the formation and adhesion of insulating films, etc. on the target surface, high-frequency power is applied to the target, and the plasma space tends to expand outside the inter-target space, which tends to deteriorate the film quality of the thin film on the substrate surface. There is also the advantage that there is no need to forcefully use a power source, and high-quality thin film formation can be performed by selectively using a DC power source.

Furthermore, since reactive gases do not enter the plasma space, target sputtering can be efficiently performed using argon ions, and even when depositing an insulating thin film, target sputtering speed and This method also has the unexpected effect of increasing the rate of film formation on the substrate surface.

Furthermore, according to the facing target sputtering method according to the present invention, it is possible to easily cause a reactive gas to react with target atoms without actively ionizing the reactive gas using a special device, and the plasma space can be directly connected to the substrate. You can avoid exposing it to the surface. Ideal for forming high-quality thin films.

Further, according to the method of the present invention, the argon gas is introduced from a gas introduction port provided facing the space between the targets, and the reactive gas is introduced from another gas introduction port along the substrate surface. Each gas can be supplied to efficiently effect sputtering and reaction with target atoms, which has the advantage of reducing the consumption of these gases, ensuring each reaction action, and further improving the film quality of the thin film.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing one embodiment of a facing target type sputtering apparatus used for carrying out the thin film forming method according to the present invention. FIG. 2 is an explanatory diagram showing another embodiment of the present invention. FIG. 3 and FIG. 4 are explanatory diagrams showing a conventional example. 1... Vacuum chamber 3, 3... Target 5.
...Space part 7... Board 8.9... Inlet

Claims (1)

[Claims] 1. A voltage is applied to the targets 3, 3 under conditions in which argon gas is introduced into a vacuum chamber 1 in which a pair of targets 3, 3 are provided facing each other, and no reactive gas is introduced. is applied to form a plasma space in which target atoms are scattered in the space 5 between the targets, and then, after the formation of the plasma space, a reactive gas is separately introduced into the vacuum chamber 1. Formation of a thin film by reactive sputtering in a facing target sputtering method characterized by reacting a reactive gas with target atoms deposited on a substrate 7 placed on the side of the substrate 7 at a position outside the plasma space. Method. 2. In claim 1, argon gas is introduced from the gas inlet 8 provided facing the space 5 between the targets, and the reactive gas is introduced to the side of the placement position of the substrate 7. A method for forming a thin film by reactive sputtering in a facing target sputtering method, characterized in that the gas is introduced from a gas inlet 9 along the substrate surface.