JPH05331634A - Sputtering device - Google Patents

Abstract

PURPOSE:To prevent abnormal discharge and to form a film of uniform quality on the surface of a substrate at an excellent film forming rate by intermittently impressing positive voltage or zero voltage in a short time on a cathode fixed with a target in a sputtering device. CONSTITUTION:In the objective sputtering device, at the time of impressing negative voltage on a cathode 2 fixed with a target by a DC power source 1, introducing Ar and a reactive gas therein to generate plasma 3 by glow discharge, ionizing the gaseous Ar and bombarding the target with it to form the thin film of the target material on the surface of a substrate 4, the cathod 2 is made rotary and the voltage to be applied is changed so that the positive potential or zero potential will be formed with the negative voltage, by which the generation of an arcing phenomenon caused by abnormal discharge is remarkably reduced, and the thin film of uniform and excellent quality by the target material or the compound in the target material is formed at a high speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering device. In particular, the present invention provides a sputtering apparatus capable of preventing arcing and performing high-quality film formation at high speed.

[0002]

2. Description of the Related Art Cathodes for direct current sputtering (hereinafter, sputtering may be simply referred to as sputtering) cannot perform high-quality film formation at high speed unless the problem of abnormal discharge is solved. The abnormal discharge that occurs around the cathode depends on various causes, but electric charges are accumulated in the minute area of the insulator that is deposited or generated on the target material surface,
It is the surrounding substrate, the anode electrode, the inner wall of the vacuum chamber,
Or, it is often due to an abnormal discharge of a kind (hereinafter referred to as arcing) that causes arc discharge temporarily toward a potential-opposed portion such as the target surface.

Arcing often occurs especially when a product of an insulator is produced from a conductive target material by reactive sputtering. When arcing occurs, glow discharge that is effective for sputtering cannot be sustained stably, the film formation rate becomes extremely unstable, and uniform quality film formation cannot be achieved.In some cases, arc discharge causes film formation. This has an adverse effect such as damage to the substrate on which the film is formed. A conventional method for avoiding this is 13.56.
A method using a high frequency power of MHz is popular.

[0004]

However, in consideration of the purpose of applying a larger amount of power to form a high-quality film at a higher speed, a sputtering apparatus using a 13.56 MHz high-frequency power supply has an output of 10 kW or more. However, it was difficult to realize it because the power supply for the power supply became bulky and expensive, and a high-voltage, large-current impedance matching circuit was required.

[0005]

In order to reduce the occurrence of arcing described above, the present invention is characterized in that a DC power source for applying an intermittent DC voltage is provided to a cathode arranged in a vacuum chamber. Is provided.

The present invention also provides a sputtering apparatus characterized in that a plasma gun capable of supplying plasma and a power source for applying an intermittent DC voltage to the cathode are provided around the cathode arranged in a vacuum chamber. Is.

Sputtering is carried out by bombarding the constituent atoms of the target material by causing positively charged gas ions in the plasma to collide with the cathode to which the target material kept at a negative potential is fixed. At this time, if there is an insulator having a small area that is deposited or generated on the target surface, gas ions accumulate there, and the insulator has a positive potential and a potential difference occurs on the target surface. This is the trigger for arcing.

In order to suppress the arcing, it suffices to suppress the charging of the insulator, and for that purpose, the target potential may be temporarily set to zero or positive to neutralize the charging of the insulator. That is, the electrons in the plasma near the target may be attracted. For that purpose, intermittent DC voltage may be applied so that sputtering can be performed.

Therefore, the present inventor has invented a sputtering apparatus using a DC power supply capable of intermittently turning on and off the output at a speed of up to several tens of microseconds, which can be realized by recent large current, high speed switching transistor circuit technology.

In normal glow discharge, glow plasma remains on the order of m seconds even immediately after the voltage of the cathode is cut off. This is called afterglow. Therefore, if the potential of the cathode is set to zero or positive while the afterglow remains, the electrons in the afterglow can neutralize the charge of the insulator on the surface of the target material.

FIG. 1 is a block diagram for explaining an embodiment of the present invention. 1 is a DC power supply, 2 is a cathode, 3 is plasma,
Reference numeral 4 is a substrate on which a thin film is formed by sputtering.

When the potential of the cathode becomes positive, the action of neutralizing the potential of the insulator is instantaneously performed. Therefore, as shown in FIG. 2, when the output waveform is longer when the cathode is negative and when the cathode is positive, the sputtering can be performed more efficiently. Also,
The same effect can be obtained by temporarily setting the potential to zero as shown in FIG.

The above-mentioned effects can be realized by a normal planar type cathode, a planar type magnetron cathode and a rotating cathode.

Since the rotating cathode has a higher cooling efficiency than the ordinary planar magnetron cathode, it has the advantages of being able to apply a large amount of electric power, increasing the film forming speed, and being highly efficient in using the target material. Having has US Pat. Nos. 4,356,073, 442,291
No. 6, JP-A-58-500174, JP-A-60-59.
No. 067 and the like.

Further, since the effect of the present invention is obtained if the plasma exists near the cathode when the cathode potential becomes zero or positive, it is possible to introduce the plasma generated by means such as a plasma gun to the vicinity of the cathode. The effect of the present invention can be realized.

[0016]

【Example】

[Example 1] An intermittent DC voltage (-600 V, application time 9 msec, non-application time 1 msec repeated) was applied to one rotating cathode to perform reactive sputtering. The target material is Si to which Al is added by 2 to 3%. A gas in which Ar and O2 were mixed at a ratio of 1: 1 was used as an introduction gas so that Al-doped SiO2 could be formed as a reaction product.
The pressure during discharge was maintained at 2.0.times.10@-3 Torr. The input power was 10 kW. At this time, the average number of arcing generated per second was 0.01 times.

Comparative Example 1 A non-intermittent DC power source was simultaneously applied to the same rotating cathode as in Example 1 under the same conditions. The input power was 10 kW. At this time, the average number of arcing generated per second was about 10.

Example 2 The rotating cathode of Example 1 was used, and a plasma flow was introduced in the vicinity of the cathode from a plasma gun which was placed adjacent to the rotating cathode and utilized arc discharge. The same intermittent DC power supply as in Example 1 was connected to the cathode, and reactive sputtering was performed. The target material, the type of introduced gas, and the pressure during discharge were the same as in Example 1. The input power was 10 kW, and the plasma gun was about 60 V and 100 A.
At this time, the effect of reducing arcing was similar to that in Example 1.

Comparative Example 2 Instead of the intermittent DC voltage of Example 2, a non-intermittent DC voltage was used. Example 2 other than this
Same as. As a result, the average number of arcing was about 10 times per second.

[Embodiment 3] Intermittent DC voltage (-600)
V, application time 9 ms, non-application time 1 ms) was applied to one planar magnetron cathode for reactive sputtering. Target material is 2-3% Al
It is the added Si. Ar and O2 as the introduction gas are 1:
A gas mixed in a ratio of 1 was used to allow Al-doped SiO2 as a reaction product. The pressure during discharge is
It was maintained at 2.0.times.10@-3 Torr. Input power is 10kW
And At this time, the average number of arcing generated per second was 0.01 times.

Comparative Example 3 A discontinuous DC power supply was simultaneously applied to the same planar type magnetron cathode as in Example 3 under the same conditions. The input power was 10 kW. At this time, the average number of arcing per second is about 1
It was 0 times.

Example 4 The planar magnetron cathode of Example 3 was used, and a plasma flow was introduced in the vicinity of the cathode from a plasma gun which was placed adjacent to the planar magnetron cathode and utilized arc discharge. The same intermittent DC power supply as in Example 3 was connected to the cathode, and reactive sputtering was performed. The target material, the type of introduced gas, and the pressure during discharge were the same as in Example 3. Input power is 10kW, plasma gun is about 60
V and 100A. At this time, the effect of reducing arcing was similar to that in Example 3.

Comparative Example 4 Instead of the intermittent DC voltage of Example 4, a non-intermittent DC voltage was used. Example 4 other than this
Same as. As a result, the average number of arcing was about 10 times per second.

[0024]

According to the sputtering apparatus of the present invention,
Even when reactive sputtering is performed, the frequency of occurrence of arcing can be reduced, and more electric power can be stably supplied to the cathode, so that an apparatus having high film forming ability can be realized.

[Brief description of drawings]

FIG. 1 is a configuration diagram illustrating an embodiment of the present invention.

FIG. 2 is a graph showing an output waveform of an example of an intermittent DC power supply used in the present invention.

FIG. 3 is a graph showing an output waveform of an example of an intermittent DC power supply used in the present invention.

[Explanation of symbols]

 1: Intermittent DC power supply 2: Cathode 3: Plasma 4: Substrate on which thin film is formed

Claims (5)

[Claims] 1. A sputtering apparatus characterized in that a DC power supply for applying an intermittent DC voltage is provided to a cathode arranged in a vacuum chamber. 2. A sputtering apparatus provided with a plasma gun arranged in a vacuum chamber capable of supplying plasma around the cathode, and a power source for applying an intermittent DC voltage to the cathode. 3. A sputtering apparatus according to claim 1, wherein a rotating cathode is used as the cathode. 4. A DC voltage having a voltage waveform in which the time when the voltage becomes zero as the intermittent DC voltage is shorter than the time when the voltage is applied is used. Sputtering equipment. 5. A DC voltage having a voltage waveform in which the time when the voltage becomes positive as the intermittent DC voltage is shorter than the time when the negative voltage is applied is used. Item of sputtering equipment.