JP3269834B2 - Sputtering apparatus and sputtering method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION This invention relates to a sputtering apparatus and vinegar
Related to the putting method . In particular, the perform sputtering apparatus of high quality film formation at high speed to prevent arcing
It relates to a sputtering method .

[0002]

2. Description of the Related Art A cathode for direct current sputtering (hereinafter, sputtering is sometimes simply referred to as sputtering) cannot perform high-speed 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.Electric charge is accumulated in a small area of insulator deposited or generated on the surface of the target material, and the charge is accumulated on the surrounding substrate, anode electrode, vacuum chamber wall, or In many cases, the discharge is caused by an abnormal discharge (hereinafter, referred to as arcing) that temporarily causes an arc discharge toward a potential counter electrode such as a target surface.

[0003] Arcing often occurs particularly when an insulating product is produced from a conductive target material by reactive sputtering. When arcing occurs, glow discharge effective for sputtering cannot be stably maintained, the film forming speed becomes extremely unstable, and film forming of uniform quality cannot be performed. Further, in some cases, there is an adverse effect such as damaging a substrate on which a film is formed by arc discharge. Conventionally, as a method of avoiding this, a method using 13.56 MHz high frequency power is often used.

[0004]

However, in order to perform high-quality film formation at a higher speed by supplying a larger power, a sputtering apparatus using 13.56 MHz high-frequency power requires 1) an output of 10%. k W more power is expensive becomes large-scaled, 2) pressure, is achieved because of such an impedance matching circuit of a large current is required it is difficult.

[0005]

According to the present invention, there is provided a sputtering apparatus having at least two rotating cathodes arranged close to each other in a vacuum chamber in order to reduce the occurrence of the arcing described above. And the same number of AC power supplies as the number of rotating cathodes that apply an AC voltage having a frequency of 100 kHz or less out of phase with each other, or 2) an intermittent DC voltage in which the turning on and off timings of each rotating cathode are shifted from each other providing the cathode and the same number of DC power source for applying a, using the sputtering apparatus and the sputtering apparatus according to claim Supattari
Provide a method of

[0006]

[0007] Sputtering is carried out by colliding positively charged gas ions in plasma with a cathode to which a target material maintained at a negative potential is fixed, and forcing out constituent atoms of the target material. At this time, if an insulator having a small area deposited or generated on the target surface is present, gas ions accumulate there, and the insulator has a positive potential and a potential difference is generated on the target surface. This is the trigger for arcing.

In order to suppress arcing, it is only necessary to prevent the insulator from being charged. To this end, the target potential may be temporarily set to zero or positive to neutralize the insulator's charge. That is, it is only necessary to attract the electrons in the plasma near the target, and for that purpose, the sputtering may be performed by applying an AC voltage or an intermittent DC voltage.

The inventor of the present invention has designed a power supply having a frequency of 100 kHz or less, which is easy to apply a large power to the cathode, such as being inexpensive and relatively easy to obtain a relatively large output and being able to perform impedance matching even with a transformer. The invented sputtering apparatus was used. The inventor has also 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.

[0010] It has been considered that a self-bias does not occur at an alternating voltage of a low frequency such as 100 kHz or less, so that the discharge does not continue and stable sputtering cannot be performed. Therefore, at least two cathodes are arranged close to each other, and when one of the cathodes becomes positive voltage or zero, the other cathode becomes negative and sustains discharge.

As a result, the neutralization of the insulator on the surface of the target material at the cathode having a positive or zero potential is performed by the electrons in the plasma generated by the other cathode having the negative potential.

[0012] Sputtering was performed while alternately performing the above operations between the two cathodes, thereby successfully reducing arcing. Further, the above-described sputtering method also has an effect of preventing generation of foreign matter due to remaining insulating material, which is a problem of conventional DC sputtering.

FIG. 1 is a schematic diagram for explaining an embodiment of the present invention. 1a and 1b are AC power supplies having a phase of 180
An AC voltage with a frequency shifted by 100 ° or less is generated. 2a and 2b are cathodes, 3 is plasma generated by an AC power supply, and 4 is a substrate on which a thin film is formed by sputtering. FIG. 1 shows an example in which there are two cathodes and two power supplies, but the present invention is not limited to this, and three or more cathodes and the same number of power supplies as cathodes can be used. When there are n cathodes, the phase of the AC voltage may be shifted by (360 ° / n).

When the potential of the cathode becomes positive, the action of neutralizing the potential of the insulator is instantaneously performed. Therefore, instead of the AC voltage, an intermittent DC voltage having an output waveform as shown in FIG. Is applied, the effect of arcing reduction is the same.
In the case of FIG. 2, the time when the cathode potential is negative is longer than the time when the cathode potential is positive, so that sputtering can be performed more efficiently. Further, even if the cathode potential is not made positive, the same effect can be obtained by temporarily making the potential zero as shown in FIG. 2 and 3, reference numerals 5 and 7 indicate voltages applied to one cathode, and reference numerals 6 and 8 indicate voltages applied to the other cathode.

In the present invention, it is preferable to use, as the intermittent DC voltage, a DC voltage having a voltage waveform in which the time when the voltage becomes zero is shorter than the time when the voltage becomes negative.
Further, as the intermittent DC voltage, it is preferable to use a DC voltage having a voltage waveform in which the time when the voltage becomes positive is shorter than the time when the voltage becomes negative.

[0016]

[0017]

[0018]

In order to sufficiently exhibit the effects of the present invention, it is preferable that at least two cathodes are arranged close to each other, and the plasma generated by one of the cathodes reaches the other cathode.

The rotating cathode has advantages such as higher cooling efficiency, higher power can be supplied, higher deposition rate, and higher target material use efficiency, as compared with a normal planar magnetron cathode. Are described in U.S. Pat. Nos. 4,356,073 and 4,422,916.
No. 58-500174, JP-A-60-590
No. 67 and the like.

Further, when the rotating cathode is used with the same operating power as the planar type, the whole cathode can be reduced in size. Therefore, two rotating cathodes are conventionally installed adjacent to a position where one planar magnetron cathode is mounted. Can also. Further, it is also effective to arrange the magnet (magnetic field generating means) 15 for converging the plasma in the rotating cathode 14 at an angle as shown in FIG. 4 so that the plasma 16 can efficiently reach around the other cathode. That is, a rotating cathode is provided as a cathode, and magnetic field generating means for plasma convergence in at least two rotating cathodes are arranged at an angle to each other, and plasma generated by at least one of the cathodes also reaches the periphery of another cathode. You can also do so.

[0022]

Also, the above-mentioned effect can be effectively reduced by using a so-called unbalanced magnetron technique in which the magnet outside the magnetron is made stronger than the inside, so that the plasma spreads more to the target surface and the substrate surface. Effective to do.

[0024]

[Example 1] Reactive sputtering was performed by applying AC voltages having phases shifted by 180 ° from two AC power sources to two rotating cathodes arranged in close proximity to each other. The target material is Al
3% added Si. A gas in which Ar and O ₂ are mixed at a ratio of 1: 1 is used as an introduction gas, and A is used as a reaction product.
1-doped SiO ₂ was made available. The pressure during the discharge was maintained at 2.0 × 10 ⁻³ Torr. Frequency is 50k
Hz, the voltage is 400 V, and the power input is 10
kW. At this time, the average number of arcing generated per second was about 0.01 per cathode for both cathodes.

Comparative Example 1 A non-intermittent DC voltage was simultaneously applied to the same rotating cathode as in Example 1 under the same conditions, and a power of 10 kW was applied to each rotating cathode. At this time, the average number of arcing generated per second was about 10 per cathode for both cathodes.

Example 2 DC voltages (-600 V, application time of 9 ms, repetition of non-application time of 1 ms) as shown in FIG. did. The input power was 10 kW per line. The other conditions were the same as in Example 1. As a result, arcing was reduced, and the same effect as in Example 1 was obtained.

[0027]

Comparative Example 2 As in Example 1, a DC voltage was applied to one of the two rotating cathodes arranged close to each other, and an AC voltage having a frequency of 50 kHz was applied to the other rotating cathode. Sputtering was performed. The input power was 10 kW for both, and the target material, the type of the introduced gas, and the pressure during discharge were the same as in Example 1. The average number of times of arcing was about 10 times per second for the rotating target to which a direct current was applied, and about 0.01 times for the one to which an alternating voltage was applied.

Comparative Example 3 Only one rotating cathode similar to that of Comparative Example 2 was used, and an AC voltage of 50 kHz was applied to the cathode to apply 10 kW.
Other than that, the same power as in Comparative Example 2 was applied. Even if an AC voltage of 50 kHz was applied, stable sputtering was impossible.

[0030]

[0031]

[0032]

[0033]

According to the sputtering apparatus of the present invention,
Even in the case where reactive sputtering is performed, the frequency of arcing can be reduced and more power can be stably supplied to the cathode, so that the film forming ability is excellent.

[Brief description of the drawings]

FIG. 1 is a schematic 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.

FIG. 4 is a configuration diagram illustrating another embodiment of the present invention.

[Explanation of symbols]

1a, 1b: AC power supply of 100 kHz or less shifted in phase from each other 2a, 2b: Cathode 3: Plasma 4: Substrate on which thin film is formed

Continuation of front page (56) References JP-A-63-190164 (JP, A) JP-A-61-41766 (JP, A) JP-A-63-140077 (JP, A) JP-A-3-56671 (JP) JP-A-63-76871 (JP, A) JP-A-64-15370 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C23C 14/00-14/58

Claims (4)

(57) [Claims] At least two adjacently disposed in a vacuum chamber
In the sputtering device provided with a number of rotary cathode, 1) in each of the rotating cathode, to the provision of the rotating cathode and the same number of alternating current power source for applying a frequency less than 100kHz of the AC voltage phase-shifted from one another, or, 2) rotating each of the cathode, providing the cathode and the same number of DC power supply for applying an intermittent DC voltage shifted from each other the timing of switching on and off, the sputtering apparatus according to claim. 2. The sputtering apparatus according to claim 1, wherein the intermittent DC voltage is a DC voltage having a voltage waveform in which the time when the voltage becomes zero is shorter than the time when the voltage becomes negative. . 3. The sputtering apparatus according to claim 1, wherein the intermittent DC voltage uses a DC voltage having a voltage waveform in which the time when the voltage becomes positive is shorter than the time when the voltage becomes negative. . 4. The spatter according to claim 1,
A sputtering method using a tarring device.