JP5850713B2 - Magnetron sputtering apparatus and magnetron sputtering method - Google Patents

Description

  The present invention relates to sputtering, and more particularly to a technique of magnetron sputtering using a magnet.

Conventionally, various types of magnetron sputtering are known (for example, see Patent Documents 1 and 2).
In recent years, for example, a process of forming an insulating material such as alumina (Al ₂ O ₃ ) by reactive sputtering in an oxygen (O ₂ ) gas atmosphere has attracted attention.

  However, when performing such a process, there are various problems. That is, during sputtering, when the flow rate of oxygen to be introduced is gradually increased while the discharge power is kept constant, the discharge voltage suddenly decreases at a certain point and then stabilizes at a low value.

On the other hand, when the flow rate of oxygen to be introduced is gradually reduced, the voltage suddenly increases at a certain oxygen flow rate and returns to a high value, and the path becomes a hysteresis.
Such a state is generally referred to as “metal mode”, “oxidation mode”, and “transition mode” between them.

Film formation in the metal mode has a high film formation speed, but a film in which the metal having an Al element ratio larger than the atomic composition ratio Al: O = 2: 3 of alumina is excessive is formed.
On the other hand, in the oxidation mode, the surface of the Al target is also oxidized and the amount of aluminum spatter is reduced. In this oxidation mode, crystalline alumina is easily formed, but the film formation rate is extremely low.

Therefore, in order to obtain both a high film formation rate and crystalline alumina, it has been attempted to form a film in a transition mode.
As a conventional technique for forming a film in the transition mode, a technique is known in which the discharge voltage is kept constant by controlling the amount of oxygen gas to be introduced by PID control.

  However, when shifting from the oxidation mode to the transition mode, for example, as shown by graphs A and B in FIG. 6A, the value of the discharge voltage rapidly decreases. Therefore, it is difficult to stabilize the discharge voltage to a desired value because the oxygen gas cannot catch up and the amount of oxygen gas introduced is too large or too small.

On the other hand, in magnetron sputtering, in order to improve the use efficiency of the target, the magnet is moved (swinged) with respect to the target.
In this method, for example, as shown in FIG. 7, the magnet 103 is reciprocated in the direction parallel to the surface of the target 101 in the vicinity of the target 101 attached to the backing plate 102. As shown in FIG. 6B, the fluctuation of the discharge voltage is larger than that when the magnet is fixed (shown by graphs C and D). In particular, it is very difficult to make the discharge voltage constant in the transition mode.

JP-A-7-258842 JP 2004-149852 A

  The present invention has been made to solve the above-described problems of the conventional technology, and an object of the present invention is to provide a discharge voltage in a magnetron sputtering apparatus including a magnet that can move relative to a target. It is in providing the technique which can stabilize.

The present invention has been made in order to achieve the above object, moving a Ma grayed magnetron sputtering apparatus, a pair of electromagnets arranged in the vicinity of both end portions of the target, between the pair of electromagnets in the vicinity of said target A permanent magnet configured to perform discharge, a discharge power source that applies a discharge voltage to the target, feeds back the value of the discharge voltage, and outputs it to the PID control unit, and an energization amount to the pair of electromagnets An electromagnet control power source for controlling the power supply, and the PID control unit determines the energization amount for the pair of electromagnets based on the discharge voltage value input from the discharge power source and the target discharge voltage value. It is configured to perform PID control .
Hand, the present invention provides a method of performing sputtering using Ma grayed magnetron sputtering apparatus described above, during the sputtering, the value of the discharge voltage that is input to the PID controller from the discharge power supply, the target The step of performing PID control so as to increase the energization amount to the pair of electromagnets so as not to exceed the value of the discharge voltage.

  According to the present invention, a discharge voltage can be stabilized in a magnetron sputtering apparatus including a magnet that can move relative to a target.

Sectional drawing which shows the internal structure of embodiment of the magnetron sputtering apparatus which concerns on this invention (A): Plan view showing an external configuration of an example of a magnet in the present invention (b): AA line sectional view of FIG. 2 (a) (A) (b): Explanatory drawing showing the principle of the present invention (A): Plan view showing the external configuration of another example of the magnet in the present invention (b): BB sectional view of FIG. 4 (a) (A): Plan view showing an external configuration of another example of the magnet according to the present invention (b): CC sectional view taken on line in FIG. (A) (b): The figure for demonstrating the subject of a prior art Diagram for explaining the problems of the prior art

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a sectional view showing an internal configuration of an embodiment of a magnetron sputtering apparatus according to the present invention.

As shown in FIG. 1, the magnetron sputtering apparatus 1 of the present embodiment has a vacuum chamber 4 connected to an evacuation system 2 and a gas introduction pipe 3.
A substrate 6 held by a substrate holder 5 is arranged, for example, in the upper part of the vacuum chamber 4.
A plurality of targets 8 made of a metal such as aluminum (Al) or silicon (Si) are placed on the backing plate 7, for example, in the lower part of the vacuum chamber 4.

In the case of the present embodiment, each target 8 is connected to an AC power source 9 provided outside the vacuum chamber 4 via a backing plate 7, for example.
The configuration of the present embodiment is a so-called dual cathode, and is configured to alternately apply an AC voltage (for example, 30 to 100 kHz) to the two targets 8.

A PID control unit 10 is connected to the AC power source (discharge power source) 9.
As will be described later, the PID control unit 10 has a function of controlling the control of the input value by three elements of the deviation between the output value and the target value, its integration, and differentiation, and is connected to the electromagnet power supply 11. ing.

  Furthermore, as will be described later, the electromagnet power supply 11 is connected to a magnet 12 having an electromagnet. And based on the command from the PID control part 10, it is comprised so that the energization amount with respect to the electromagnet of the magnet 12 from the power supply 11 for electromagnets may be increased or decreased.

For example, the magnets 12 are arranged in the vicinity of each target 8 outside the vacuum chamber 4.
Here, as will be described later, the magnet 12 has a main magnet 13 that moves (swings) in parallel with the particle emission surface of each target 8 by a driving means (not shown).

FIG. 2A is a plan view showing an external configuration of an example of a magnet according to the present invention, and FIG. 2B is a cross-sectional view taken along line AA of FIG.
As shown in FIGS. 2A and 2B, the magnet 12 of the present invention has a main magnet 13 made of permanent magnets and auxiliary magnets 14 and 15 made of electromagnets.

The main magnet 13 has an elongated shape, and is configured such that an N-pole magnet 17 made of an N-pole permanent magnet and an S-pole magnet 18 made of an S-pole permanent magnet are provided on a rectangular magnet plate 16. ing.
The N-pole magnet 17 is formed in a rectangular ring shape, and a linear rod-shaped S-pole magnet 18 is disposed at a position surrounded by the N-pole magnet 17.

On the other hand, the auxiliary magnets 14 and 15 have a straight bar-shaped core (magnetic core) 19 having a length equivalent to that of the N-pole magnet 17 of the main magnet 13. The core 19 is made of a magnetic material, and a coil 20 is wound around the core 19 to form auxiliary magnets 14 and 15.
Here, the coil 20 is connected to a power source for an electromagnet (not shown), and the winding direction and the energization direction are determined so that the surface of the core 19 on the target (not shown) side becomes an N pole.

In the present embodiment, for example, as shown in FIG. 3B, the auxiliary magnets 14 and 15 described above are arranged at both ends of the target 8.
Then, as shown in FIG. 2B, for example, the main magnet 13 is moved between the auxiliary magnets 14 and 15 in a direction parallel to the particle emission surface (not shown) of the target by a moving means (not shown). ing.

3A and 3B are explanatory views showing the principle of the present invention.
Hereinafter, the case where the magnetron sputtering apparatus 1 shown in FIG. 1 and the magnet 12 shown in FIGS. 2A and 2B are used will be described as an example.

  In general, in magnetron sputtering, as shown in FIG. 3 (a), it is known that the magnetic field strength and the discharge voltage on the target surface increase with increasing the magnetic field strength on the target surface. Yes.

Therefore, in the present invention, based on such a fact, PID control is performed to operate the magnet 12 so that the discharge voltage during sputtering approaches a predetermined target value (V ₁ ).
Specifically, when the value of the discharge voltage input from the AC power supply 9 to the PID control unit 10 (see FIG. ₁ ) exceeds the target value (V ₁ ) through the sputtering process, PID control is performed so as to increase the voltage to the electromagnet power supply 11 (see FIG. 1) and the auxiliary magnets 14 and 15 according to the three elements of deviation, integration, and differentiation.

On the other hand, when the value of the discharge voltage input from the AC power source 9 to the PID control unit is lower than the target value (V ₁ ), the electromagnet is used according to three elements: deviation from the target value, integration, and differentiation. PID control is performed so as to decrease the voltage from the power supply 11 to each auxiliary magnet 14 and 15.
In these cases, input / output responses are measured in advance in order to determine an appropriate proportional gain, integral gain (or integration time), and differential gain (or differentiation time).

  In practice, in the apparatus that performs sputtering while moving the magnet 12 as in the present embodiment, as described above, the discharge voltage rapidly increases when the magnet 12 is positioned at both ends of the target 8. 3B, when the magnet 12 is positioned at the left end 8L of the target 8, the energization amount of the auxiliary magnet 14 on the left side of the magnet 12 is increased. When the magnet 12 is positioned at the right end 8R of the target 8, the magnet 12 Control is performed so that the energization amount to the right auxiliary magnet 15 is increased.

As a result, the magnetic field strength of the surface of the target 8 is increased at the left end portion 8L and the right end portion 8R of the target 8 by the magnetic forces 14g and 15g from the auxiliary magnets 14 and 15, as shown in the graph of FIG. An increase in discharge voltage can be suppressed (V _MAX → V ₁ ).

Moreover, according to the present invention, since the current to the electromagnet is controlled, the response speed of the control is remarkably increased as compared with the case of increasing or decreasing the amount of oxygen gas introduced as in the prior art. be able to.
Therefore, according to the present invention, the discharge voltage can be stabilized in the transition mode in which the fluctuation of the discharge voltage is unstable, and crystalline material such as alumina can be formed at a high film formation rate.

4A is a plan view showing an external configuration of another example of the magnet according to the present invention, and FIG. 4B is a cross-sectional view taken along the line BB in FIG. 4A. Corresponding parts are denoted by the same reference numerals, and detailed description thereof is omitted.
As shown in FIGS. 4 (a) and 4 (b), the magnet 22 of this example is composed only of an electromagnet.

  The magnet 22 has an elongated shape. For example, first and second electromagnets 25 and 26 are mounted on a support plate 21 driven by a moving means (not shown), whereby the magnet 22 is integrated with the target. It is configured to move in a direction parallel to the particle emission surface (not shown).

The first electromagnet 25 has a core 27 formed in a rectangular ring shape, and a coil 28 is wound around the outer side surface and the inner side surface of the core 27.
Here, the coil 28 of the first electromagnet 25 is connected to an electromagnet power supply (not shown), and the winding direction and the energization direction are determined so that the surface 27a on the target side of the core 27 has an N pole.

On the other hand, the second electromagnet 26 has a straight bar-shaped core 29 disposed at a position surrounded by the first electromagnet 25, and a coil 30 is wound around the side surface of the core 29.
Here, the coil 30 is connected to an electromagnet power source (not shown), and its winding direction and energization direction are determined so that the target-side surface 29a of the core 29 has an S pole.
Even when the magnet 22 of this example having such a configuration is used, the discharge voltage can be stabilized as in the above example.

FIG. 5A is a plan view showing an external configuration of another example of the magnet according to the present invention, and FIG. 5B is a cross-sectional view taken along the line CC of FIG. 5A. Corresponding parts are denoted by the same reference numerals, and detailed description thereof is omitted.
As shown in FIGS. 5 (a) and 5 (b), the magnet 32 of this example is composed only of an electromagnet.

  The magnet 32 has an elongated shape. For example, a first electromagnet group 33 and a second electromagnet group 34 made of a large number of electromagnets are mounted on a support plate 21 driven by a moving means (not shown). Are integrally moved in a direction parallel to a particle emission surface (not shown) of the target.

  The first electromagnet group 33 includes a plurality of first electromagnets 37 each having a coil 36 wound around a side surface of a core 35 formed in, for example, a prismatic shape, and the plurality of first electromagnets 37 are supported by the support plate 21. Are arranged in an annular shape on the edge of the.

Here, the coils 36 of the first electromagnet 37 are respectively connected to an electromagnet power source (not shown), and the winding direction and the energization direction are determined so that the surface 35a on the target side of the core 35 has an N pole.
On the other hand, similarly to the first electromagnet 37, the second electromagnet group 34 includes a plurality of second electromagnets 40 each having a coil 39 wound around a side surface of a core 38 formed in a prismatic shape, for example. A plurality of second electromagnets 40 are linearly arranged at positions surrounded by the first electromagnet group 33.

Here, the coil 39 of the second electromagnet is connected to an unillustrated electromagnet power source, and its winding direction and energization direction are determined so that the surface 38a on the target side of the core 38 becomes the S pole.
When the magnet 32 of this example having such a configuration is used, in addition to the above-described effects, the energization amounts of the first and second electromagnets 37 and 40 can be controlled, respectively. The magnetic field strength can be controlled in units of small regions, and there is an effect that the discharge voltage distribution can be suppressed more uniformly.

The present invention is not limited to the above embodiment, and various modifications can be made.
For example, in the above-described embodiment, the magnetic forming means of the system that moves the magnet with respect to the stationary target has been described as an example. However, the present invention is not limited to this, and the above-described electromagnet is provided in a rotatable cylindrical target. The present invention can also be applied to a so-called cylindrical magnetic forming means in which a magnet having a magnet is disposed.

DESCRIPTION OF SYMBOLS 1 ... Magnetron sputtering apparatus 8 ... Target 9 ... AC power supply (power supply for discharge)
DESCRIPTION OF SYMBOLS 10 ... PID control part 11 ... Electromagnet power supply 12 ... Magnet 13 ... Main magnets 14, 15 ... Auxiliary magnet

Claims (2)

It is between grayed magnetron sputtering apparatus,
A pair of electromagnets disposed near both ends of the target;
A permanent magnet configured to move between the pair of electromagnets in the vicinity of the target;
A discharge power supply for applying a discharge voltage to the target and feeding back the value of the discharge voltage to the PID control unit;
An electromagnet control power source for controlling an energization amount for the pair of electromagnets;
The PID control unit is configured to PID-control the energization amount to the pair of electromagnets based on the discharge voltage value input from the discharge power supply and the target discharge voltage value. . A method of performing sputtering using a magnetron sputtering apparatus according to claim 1,
During the sputtering, PID control is performed so as to increase the energization amount of the pair of electromagnets so that the value of the discharge voltage input from the discharge power supply to the PID control unit does not exceed the target value of the discharge voltage. A magnetron sputtering method comprising the steps of:

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