JPH0953176A - DC reaction sputtering device - Google Patents

Abstract

(57) Abstract: The present invention effectively prevents abnormal discharge that occurs between the first and second electrodes in a direct current reaction sputtering device. An overvoltage absorption circuit in which a diode and a varistor are connected in series is connected in parallel to a power supply input terminal of an electrode section in which first and second electrodes are opposed to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC reaction sputtering device, which can be applied to a device for preventing abnormal discharge in a sputtering device.

[0002]

2. Description of the Related Art Conventionally, there is a DC reactive sputtering apparatus which performs reactive sputtering by adding an auxiliary power source to the DC power source of the DC sputtering apparatus. As shown in FIG. 3, in the DC reaction sputtering apparatus 1, the DC voltage of the DC power supply 2 is applied to the electrode unit 4 via the auxiliary power supply 3. A target electrode 5 made of a conductor is arranged above the electrode portion 4, and a target substance (not shown) is placed on the target electrode 5. Further, in the electrode portion 4, the work electrode 6 is arranged below so as to face the target electrode 5.
A work (not shown) is placed on top.

The DC reaction sputtering apparatus 1 is filled with the depressurized gas between the target electrode 5 and the work electrode 6 and applies a constant negative voltage shown in FIG. 4 to the target electrode 5 from the DC power supply 2. As a result, as shown in FIG. 5, the negative charge 7 appears on the target electrode 5 and gas plasma is generated in the gas atmosphere. The ionized gas collides with the target of the counter electrode and knocks out the atom of the target substance from the target. The ejected target material chemically reacts with the plasma gas and is deposited as a compound of a gas component on a work such as a semiconductor substrate placed on the work electrode 6.

When a negative charge 7 appears on the target electrode 5,
The reactive compound is attracted to the target electrode 5. If this phenomenon is left as it is, as shown in FIG. 6A, a non-conductor film 8 made of a reactive compound is formed on the surface of the target electrode 5. This film 8 accumulates a positive charge 9 on the surface and prevents atoms of the target material from jumping out of the target. Therefore, it takes a long time to deposit the compound of the gas component on the work.

On the other hand, the auxiliary power supply 3 periodically generates a positive pulse voltage and applies it to the target electrode 5 to generate a negative charge 7.
Are periodically emitted from the work electrode 6. This allows
As shown in FIG. 7, while the positive voltage is being applied to the target electrode 5, the positive charge 9 accumulated on the surface of the target electrode 5 is neutralized as shown in FIG. 6 (B). Therefore,
The non-conductive film is not formed on the target electrode 5, the amount of the target substance jumping out from the target is stabilized, and the time for depositing the reactive spatula compound is shortened.

In the DC reaction sputtering device 1, when the gas pressure, gas type, applied voltage, etc. are changed, a large abnormal discharge may occur on the work side (work electrode 6 side) and damage may occur on the work side. Therefore, as shown in FIG. 8, in an ordinary DC sputtering device, the anode and cathode of the diode 10 are connected to the target electrode 5 and the work electrode 6, respectively. Thereby, the large voltage generated by the abnormal discharge is bypassed by the diode 10, and the abnormal discharge can be avoided.

[0007]

In the DC reaction sputtering device 1 described above, it is conceivable to simply connect the diode to the target electrode 5 and the work electrode 6.
However, in this method, the positive voltage periodically applied to the cathode is also bypassed by the diode, and the positive charge attracted to the target electrode 5 cannot be neutralized. Therefore, when an abnormal discharge occurs and an excessive reverse voltage is generated, it is inevitable that the abnormal discharge occurs again from a part of the work.

The present invention has been made in consideration of the above points, and an object thereof is to propose a DC reaction sputtering device which prevents abnormal discharge occurring between the first and second electrodes.

[0009]

In order to solve such a problem, the present invention has an electrode portion in which a first electrode faces a second electrode, and a negative voltage generated by a first DC power source is used. , The positive voltage generated by the second DC power source periodically,
In the DC reaction sputtering device for applying to the electrode, the overvoltage absorption circuit is connected in parallel with the power input terminal of the electrode section. In the overvoltage absorption circuit, a diode and a varistor are connected in series. By connecting the overvoltage absorption circuit in which the diode and the varistor are connected in series to the power input terminal of the electrode portion in parallel, it is possible to effectively prevent abnormal discharge that occurs between the first and second electrodes.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1, in which parts corresponding to those in FIG. 3 are designated by the same reference numerals, shows a DC reaction sputtering device 11 as a whole.
The DC reaction sputtering device 11 is a DC reaction sputtering device 1.
In this configuration, the electrode portion 12 is provided instead of the electrode portion 4. The electrode section 12 has an overvoltage absorption circuit 13 in addition to the configuration of the electrode section 4, and the overvoltage absorption circuit 13 is connected in parallel to the power supply input terminal.

In the overvoltage absorption circuit 13, a diode 14 and a varistor 15 are connected in series. Diode 1
An anode 4 is connected to a first electrode, for example, a target electrode 5, and a cathode is connected via a varistor 15 to a second electrode, for example, a work electrode 6. As shown in FIG.
The varistor 15 exhibits non-conductivity when the voltage applied across the varistor voltage is below a certain value, the so-called varistor voltage. When the voltage applied across the varistor voltage exceeds the varistor voltage, the varistor 15 exhibits extremely high conductivity and a large current. Shed. As a result, the overvoltage absorption circuit 13 separates the low reverse voltage required for the target electrode 5 and the unnecessary excessive reverse voltage, and bypasses only the excessive reverse voltage to the work electrode 6.

In the above structure, when a negative voltage is applied to the target electrode 5, the overvoltage absorption circuit 13 maintains the non-conduction state because the diode 14 is non-conduction. Next, when a low negative pulse voltage is applied to the work electrode 6 by the second power source, for example, the auxiliary power source 3, the positive charges attracted to the target electrode 5 are neutralized. At this time, the diode 14 becomes conductive. On the other hand, the varistor 15 maintains the non-conductive state because the pulse voltage is lower than the varistor voltage. As a result, the overvoltage absorption circuit 13 maintains the non-conduction state.

Next, when an excessive reverse voltage due to abnormal discharge or the like is applied between the target electrode 5 and the work electrode 6, the diode 14 and the varistor 15 simultaneously conduct, bypassing the excessive reverse voltage to the work electrode 6. As a result, abnormal discharge is effectively suppressed. Therefore, the work placed on the work electrode 6 can be prevented from being damaged by the abnormal discharge.

According to the above structure, the overvoltage absorption circuit 13 in which the diode 14 and the varistor 15 are connected in series is connected in parallel to the power input terminal of the electrode portion 12, so that it is generated between the target electrode 5 and the work electrode 6. It is possible to effectively prevent the abnormal discharge that occurs.

[0016]

As described above, according to the present invention, the overvoltage absorption circuit in which the diode and the varistor are connected in series is connected in parallel to the power supply input terminal of the electrode portion where the first and second electrodes are opposed to each other. As a result, it is possible to realize a DC reaction sputtering device that can effectively prevent abnormal discharge that occurs between the first and second electrodes.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of a DC reaction sputtering device according to the present invention.

FIG. 2 is a characteristic curve diagram showing varistor characteristics.

FIG. 3 is a schematic diagram showing a conventional DC reaction spatula device.

FIG. 4 is a schematic diagram showing a voltage applied by a DC power supply.

FIG. 5 is a schematic diagram showing a state of a target electrode in the case of DC sputtering.

FIG. 6 is a schematic diagram showing a state of charge accumulation and neutralization with respect to a target electrode.

FIG. 7 is a waveform diagram showing a combined applied voltage by a DC power supply and an auxiliary power supply.

FIG. 8 is a connection diagram showing an abnormal discharge prevention circuit added to an electrode portion.

[Explanation of symbols]

1, 11 ... DC reaction sputtering device, 2 ... DC power supply,
3 ... Auxiliary power source, 4, 12 ... Electrode part, 5 ... Target electrode, 6 ... Work electrode, 7 ... Negative charge, 8 ... Non-conductive film, 9 ... Positive charge, 10, 14 ... … Diodes, 1
3 ... Overvoltage absorption circuit, 15 ... Varistor.

Claims (1)

[Claims] 1. A negative voltage generated by a first direct-current power supply and a positive voltage periodically generated by a second direct-current power supply having an electrode portion in which a first electrode faces a second electrode. In the direct current reaction sputtering device for applying the above-mentioned to the first electrode, a diode and a varistor are connected in series, and a direct current reaction characterized by comprising an overvoltage absorption circuit connected in parallel with the power input terminal of the electrode part is provided. Spatter device.