JPH07243039A - Dc-magnetron reactive sputtering method - Google Patents

Abstract

PURPOSE:To conduct stabilized sputtering for a long time. CONSTITUTION:In this DC-magnetron reactive sputtering method, the magnetic field of a magnet 3 disposed on the rear side of a target 4 is moved to form an erosion region over the whole surface of the target, hence the formation of a reaction product layer is suppressed on the target surface, and further a negative DC voltage contg. a pulse having a positive peak voltage is impressed on a magnetron cathode 2 to doubly prevent the generation of an abnormal discharge on the target surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC magnetron type reactive sputtering method.

[0002]

2. Description of the Related Art Conventionally, in the DC magnetron type reactive sputtering method, an insulator target is treated by introducing a reactive gas into the film forming chamber during sputtering. Due to the film formation on the material, a thin insulator is created on the target surface, which is a conductor, in a short time, which causes a charge-up phenomenon, and abnormal discharge (arc discharge) occurs due to this charge-up phenomenon. However, there is a problem that sputtering cannot be performed stably. Therefore, JP-A-64-153
No. 70 publication, a DC voltage is intermittently applied to the cathode,
That is, a method has been proposed in which a DC power supply is provided with a circuit for turning power on and off and a negative voltage is applied to the cathode to prevent abnormal discharge.

However, since the peak voltage applied intermittently is 0 V (ground level), the charge-up cannot be sufficiently canceled, and it is difficult to maintain stable discharge for a long time. did. On the other hand, in the DC magnetron-type reactive sputtering method, in the non-erosion region of the target with a small parallel magnetic field component to the target, a reactant generation layer that is an insulator is formed and increases over time, which also stabilizes the discharge. It has been found that this is one of the causes that prevent the conversion.

[0004]

In order to solve the above problems, the present invention is directed to a direct current magnetron type reactive sputtering method in which the magnetic field of a magnet disposed on the back surface side of the target is moved so that the erosion region of the target is changed. A negative DC voltage including a pulse having a positive peak voltage is applied to the magnetron cathode while being formed on the entire surface.

[0005]

As described above, according to the present invention, the erosion region moves on the surface of the target, and the entire surface becomes the erosion region, so that the reactant generation layer that increases with time is not formed on the target. Moreover, since the peak voltage is a pulsed DC voltage having a positive voltage, charge-up on the target surface due to an extremely thin insulator formed on the target surface in an extremely short time is suppressed.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an outline of a DC magnetron type reactive sputtering apparatus to which the present invention is applied.
Is supplied with a discharge gas and is connected to an exhaust means so that the inside of the vacuum film forming chamber 1 has a predetermined pressure. Reference numeral 2 is a magnetron cathode attached to the vacuum film forming chamber 1. Inside the magnetron cathode 2, a permanent magnet 3 described below is arranged to apply a magnetic field to the surface of the target 4. In addition, 5 is a board | substrate. A direct current power supply 6 is connected to the magnetron cathode 2 and a circuit for applying the following peak voltage to the magnetron cathode 2 is provided in the direct current power supply 6.

Next, the magnetron cathode 2 and the target 4 will be described in detail. First, when the magnetron cathode 2 and the target 4 are round, the permanent magnet 3 is arranged as shown in FIG. 2, and the permanent magnet 3 is rotated by a motor or the like with the center of the target 4 as an axis. That is, when the permanent magnet 3 of FIG. 2 is illustrated, the erosion area on the target 4 generated by the permanent magnet 3 is as indicated by the diagonal lines of FIG. 3, and when the permanent magnet 3 rotates as described above, the erosion area is generated. Will be formed on the entire surface of the target 4.

FIG. 4 shows a case where the magnetron cathode 2 and the target 4 are rectangular. The permanent magnet 3 has an oval shape, and by moving the permanent magnet 3 left and right as shown in FIG. The entire surface of the target 4 is used as an erosion area. In FIGS. 2 and 4, the horizontal direction and the vertical direction refer to the paper surface. Also,
As the arrangement of the permanent magnets 3, various arrangements other than those shown in FIGS. 2 and 4 are applied.

Next, the sputtering method of the sputtering apparatus having the above structure will be described. The substrate 5 is attached to a holder (not shown), the discharge gas is supplied into the vacuum film forming chamber 1 and a predetermined pressure is set, and the permanent magnet 3 is rotated or reciprocated while the DC power source 6 is applied to the magnetron cathode 2 to -200 ≦ V. A cathode potential of ≦ −1500 (V) is applied, and a peak voltage of 0 <V ≦ 300 (V) in which the positive potential peak is on the positive potential side of the anode (earth) potential is applied. In this case, the pulse frequency is 100
Hz to 100 kHz (see FIG. 6).

The peak voltage is applied to periodically neutralize the extremely thin surface insulating layer locally generated on the surface of the target 4 during sputtering, and the electric charge charged up in the space surrounding the surface insulating layer, thereby causing abnormalities. Prevent the occurrence of discharge.

The peak voltage has no effect of charge neutralization unless the potential of the magnetron cathode 2 is instantaneously at least on the plus side of the anode (earth) potential. On the contrary, the above range is preferable because abnormal discharge is caused.

If the pulse frequency is too low, charge neutralization will not be in time and abnormal discharge will occur. On the contrary, if the pulse frequency is too high,
The above range is preferable because the film forming efficiency is lowered and the temperature of the substrate 5 is increased.

On the other hand, in the target 4, as the permanent magnet 3 moves, its magnetic field also moves, and the entire surface of the target 4 is set as an erosion region. Therefore, the permanent non-erosion region in the target 4 disappears, and the surface of the target 4 disappears. The growth of the reactant generation layer in the above is suppressed, and the discharge can be stabilized. For example, in DC magnetron type reactive sputtering of a SiN film using a conductive Si target, stable discharge is possible for about 30 minutes to 1 hour at the initial stage of film formation when only a pulse voltage is applied.
Above that, the amount of growth of the reactant generation layer on the target surface increased and discharge became unstable. If only the magnet is moved, growth of the reaction product generation layer on the target surface can be prevented, but the cause of abnormal discharge due to the thin insulator that occurs in a very short time during the movement of the magnet remains, and there is no tendency to increase with time. However, some abnormal discharge was observed from the initial stage of discharge. As described above, the present invention achieves stable discharge for 7 hours or more by combining pulse voltage application and magnetic field movement.

Although the permanent magnet 3 is used as the magnet in the above embodiment, the present invention is not limited to this, and an electromagnet may be used to change the current.

[0015]

As is clear from the above description, according to the present invention, the erosion region moves over the entire surface of the target, so that the growth of the reaction product layer on the target surface is suppressed and the discharge is stabilized. be able to. In addition, since a pulsed DC voltage having a positive peak voltage is applied,
Prevents abnormal discharge by suppressing charge-up on the target surface. As described above, according to the present invention, the above-described effects are combined, and the stable film formation operation can be performed for a long time (7 hours or more).

[Brief description of drawings]

FIG. 1 is a schematic diagram of a DC magnetron type reactive sputtering apparatus to which the present invention is applied.

FIG. 2 is a diagram showing a relationship between a target and a permanent magnet.

FIG. 3 is a diagram showing an erosion region of a target in the state of FIG.

FIG. 4 is a diagram showing another embodiment of FIG.

FIG. 5 is a diagram showing an erosion region of a target in the state of FIG.

FIG. 6 is a waveform diagram showing a voltage applied to a magnetron cathode (target).

[Explanation of symbols]

1 ... Vacuum film forming chamber, 2 ... Magnetron cathode, 3 ... Magnet, 4 ... Target, 5 ... Substrate.

Front page continuation (72) Inventor Eiji Furuya 2-4-7 Kyomachibori, Nishi-ku, Osaka-shi, Osaka Chugai Furnace Industry Co., Ltd.

Claims (1)

[Claims] 1. In the direct current magnetron type reactive sputtering method, the magnetic field of a magnet disposed on the back surface side of the target is moved to form an erosion region on the entire surface of the target, and the peak voltage of the magnetron cathode is a positive voltage. DC magnetron-type reactive sputtering method characterized in that a negative DC voltage including a pulse is applied.