JP3020189B2 - Thin film formation method by bias sputtering - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bias sputtering method in which a high-frequency power is applied to both a target and a substrate electrode to form a plasma between both electrodes by discharge, thereby forming a thin film on the substrate surface.

[0002]

2. Description of the Related Art Conventionally, when a thin film is formed on a substrate having a step on the surface, the above-described bias sputtering method has been adopted in order to improve the coverage of the step.

For example, in the process of forming an alumina protective film of a thin film head for writing and reading data on and from a magnetic recording medium, a target and a target are formed in a short time to form a thick film (several tens of μm) over a large area. This bias sputtering method is employed by setting the distance between the substrate electrodes as short as 20 to 40 mm.

[0004]

In the above-described bias sputtering method, when the distance between the target and the substrate electrode is set short, there is a problem that it is difficult to start discharge for sputtering.

In a sputtering apparatus, a discharge can be started by a method of temporarily increasing the pressure in a vacuum vessel containing a target and a substrate electrode, or by starting an arc discharge with another electrode placed around the target. Then, a method of inducing a discharge between the target and the substrate electrode, a method of emitting thermoelectrons from the filament to supply electrons for discharge between the target and the substrate electrode, and the like are known.
When the distance between the target and the substrate electrode was set short, none of the methods was effective for starting discharge.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object to provide a method of forming a thin film by bias sputtering which facilitates discharge initiation.

In the method of forming a thin film by bias sputtering according to the present invention, which achieves the above object, a high-frequency power is applied to both a target and a substrate electrode to form a plasma between both electrodes by discharge, thereby forming a thin film on the substrate surface. In the bias sputtering method, after the distance between the target and the substrate electrode is set to a distance at which discharge can be started and discharge is started, the distance between the target and the substrate electrode is changed while maintaining the discharge state . Thin film formation at difficult distances to start
The method is characterized in that a required thin film is formed on the substrate surface by setting the distance to an excellent value .

Prior to the proximity of the target and the substrate electrode, a sputter etch for cleaning the substrate surface and a pre-sputter for the purpose of cleaning the target surface may be performed by interposing a shutter plate between the two electrodes. good.

[0009]

According to the present invention, after the discharge is started, the target and the substrate electrode are brought close to each other to maintain the discharge.
The process of forming a thin film over a large area in a short time can be efficiently advanced.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.
FIG. 1 is a configuration diagram of a bias sputtering apparatus used in the embodiment. A target 2 and a substrate electrode 3 are placed inside a vacuum vessel 1.
Are installed facing each other. The target 2 is bonded to a base 5 attached to a target electrode 4. The substrate electrode 3 is configured such that the substrate 6 can be placed on the upper surface.

The substrate electrode 3 and the target electrode 4 can be cooled by a water cooling structure (not shown), respectively, and high-frequency power sources 7 and 8 are connected to supply high-frequency power between the target 2 and the substrate 6. It has been like that.

The inside of the vacuum vessel 1 can be evacuated by a vacuum pump 9, and an argon gas or other sputtering gas can be introduced from a gas introduction system (not shown) through an introduction port 10. At the time of sputtering, the inside can be adjusted to an atmosphere of a predetermined pressure. In the figure, reference numeral 11 denotes an insulating member.

The substrate electrode 3 is provided on the bottom wall 1a of the vacuum vessel 1.
Is supported by an elevator 13 provided via a bellows 12, and the elevator 13 is moved up and down by an air cylinder 14 installed between the bottom electrode 1 a and the substrate electrode 3. It can be separated and connected.

The vacuum vessel 1 has a retreat space 16 for a shutter plate 15 on one side. Shutter plate 15
Is provided by the moving mechanism (not shown) in the evacuation space 16.
, And can move between the opposing space 17 between the target 2 and the substrate electrode 3.

FIG. 1 shows a structure in which a target 2 and a substrate electrode 3 are used in order to increase the film forming speed and secure a large surface treatment area.
This indicates a state in which the facing distance between them is as close as possible. In this state, it is difficult to cause a discharge between the target 2 and the substrate electrode 3.

Therefore, when forming a thin film on the surface of the substrate 6, first, as shown in FIG.
Is operated, the substrate electrode 3 is lowered via the elevating table 13, the facing distance to the target 2 is set to a distance at which discharge can be started, and power is supplied from the high frequency power supplies 7 and 8 to connect the target 2 to the target 2. A discharge is generated between the substrate electrodes 3 to start bias sputtering.

Next, the air cylinder 14 is operated,
When the substrate electrode 3 is raised via the lifting table 13 and brought into the proximity state as shown in FIG. 1, the discharge can be continued without interruption, and the substrate can be formed over a wide area at a high film forming speed. 6 can be performed.

An example of the distance between the target 2 and the substrate electrode 3 is about 35 at the start of discharge (the state shown in FIG. 2).
mm, and about 15 mm when forming a thin film (the state of FIG. 1).

FIG. 3 shows a case where the substrate plate 3 is lowered to a position farther away at the start of the discharge so that the shutter plate can be moved into the space 17 between the target 2 and the substrate plate 3. is there.

When the shutter plate 15 is inserted between the electrodes at the start of the discharge, the discharge between the shutter plate 15 and the substrate electrode 3 causes the substrate 6 placed on the substrate electrode 3 to discharge.
Can be cleaned by sputter etching.

Further, the surface of the target 2 can be cleaned by pre-sputter by the discharge between the shutter plate 15 and the target 2.

Accordingly, after the sputter etching and the pre-sputtering are performed with the interval between the target 2 and the substrate electrode 3 as shown in FIG. 3, the shutter plate 15 is retreated to the retreat space 16 and the substrate electrode 3 is raised. As shown in FIG. 1, by maintaining the discharge in the proximity state, a thin film having a small amount of impurities can be formed over a wide area at a high film forming speed.

In a conventional bias sputtering apparatus in which a target and a substrate electrode are brought close to each other, it is extremely difficult to start discharge when a shutter plate is inserted between the two electrodes. Therefore, the shutter plate is configured to be able to be inserted at a position very close to the substrate electrode so as to be as far away from the target as possible.In a state where the shutter plate is retracted, first the substrate side is sputter-etched, and then the shutter plate is inserted. A method of pre-sputtering a target has been adopted. Therefore, in the pre-sputtering, it is necessary to remove the film adhered to the target at the time of the sputter etching, and a long-time treatment is required.

[0024]

As described above, according to the present invention, the discharge can be easily and reliably started, and the substrate surface can be treated at a high film forming speed over a wide area.

Before bringing the target and the substrate electrode close to each other,
If a shutter plate is inserted between both electrodes and sputter etching of the substrate surface and pre-sputtering of the target are performed,
A thin film with few impurities can be formed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a bias sputtering apparatus used in an embodiment of the present invention.

FIG. 2 is an explanatory diagram at the start of discharge in an embodiment of the present invention.

FIG. 3 is an explanatory diagram of another embodiment of the present invention at the start of discharge.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum container 2 Target 3 Substrate electrode 4 Target electrode 6 Substrate 7, 8 High frequency power supply 9 Vacuum pump 12 Bellows 13 Lifting table 14 Air cylinder 15 Shutter plate

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 21/203 H01L 21/208 C23C 14/00-14/58

Claims (2)

(57) [Claims] In a bias sputtering method in which high-frequency power is applied to both a target and a substrate electrode to form plasma by discharge between the two electrodes and form a thin film on a substrate surface, a distance between the target and the substrate electrode is increased. Start the discharge
After setting allows the distance to initiate the discharge, while maintaining the discharge state, discharging the distance between the target and the substrate electrode
At a distance where it was difficult to start
A method of forming a thin film by bias sputtering, wherein a desired thin film is formed on a substrate surface by setting . 2. A thin film forming method by bias sputtering according to claim 1, wherein a sputter etching and a pre-sputtering are performed by interposing a shutter plate between the two electrodes before the target and the substrate electrode are brought close to each other.