JP2020084230A - Sputtering method and sputtering apparatus - Google Patents

Abstract

To provide a technique capable of constantly maintaining a film deposition rate when forming an insulation film of oxide, nitride and the like for a long term by sputtering using high frequency electric power.SOLUTION: A sputtering method comprises: arranging an unevenness anode electrode part 8 having an uneven structure forming potential equal to that of an anode electrode during sputtering in a discharge space; rotating and moving an anode area control member 9 including a shield part 9B for shielding the substrate side recessed part 8a of the unevenness anode electrode part 8 to the discharge space and an anode area control hole 9a for exposing the substrate side recessed part 8a to the discharge space; and controlling the self-bias voltage of high frequency electric power so as to be constant by changing the exposed area of the substrate side recessed part 8a of the unevenness anode electrode part 8 in the discharge space to increase the area of the anode electrode.SELECTED DRAWING: Figure 1

Description

The present invention relates to an apparatus for forming a film by sputtering, and particularly to a technique of a sputtering apparatus for forming an insulating film by RF (radio frequency) sputtering.

2. Description of the Related Art In recent years, with the miniaturization of devices due to higher performance and higher functionality, the film thickness of the thin film forming the device has become thinner and thinner. Therefore, it is more important than ever to control the film thickness.

When a thin film is formed by a sputtering method using high frequency power, the area of the anode electrode plays a very important role in controlling the film formation rate.

In particular, when the material to be deposited on the substrate on the stage is an insulating material such as oxide or nitride, the impedance of the anode electrode surface increases due to the deposition of the insulating film on the anode electrode surface, making it difficult to function as an anode electrode. Become.

That is, it is known that when an insulating film is formed over a long period of time by a sputtering method using high frequency power, the area of the anode electrode is gradually decreased and the film formation rate is gradually decreased.

As a method of suppressing this problem, conventionally, an anode electrode portion facing a target is provided around a stage on which a substrate is installed, and a circular concave structure having a diameter of about 10 mm facing the target (a structure such as a pencil stand). ) Is known (see, for example, Patent Document 1).

This structure increases the area of the anode electrode, and since it is difficult for the insulating film to deposit inside the recess, it is used as a method of suppressing changes in the film formation rate when forming the insulating film for a long period of time. ing.

However, even when the change in the film formation rate is suppressed by such means, when the insulating film is deposited on the surface of the anode electrode portion, the initial cycle of the film formation cycle is longer than that in the case of long-term film formation. In comparison, the film forming rate slightly changes (decreases) near the end of the film forming cycle, which may cause a problem.

JP, 2002-38263, A

The present invention has been made in view of the above problems of the conventional technique, and its object is to form an insulating film such as an oxide or a nitride for a long time by sputtering using high frequency power. Another object of the present invention is to provide a technique capable of keeping the film formation rate constant.

The present invention made to achieve the above object is to supply alternating power between a cathode electrode and an anode electrode in a vacuum to cause discharge in a discharge space, and to sputter a target to form an insulating film on a substrate. In the sputtering method, a concavo-convex anode electrode portion having a concavo-convex structure having a potential equal to that of the anode electrode during sputtering is arranged in a discharge space, and a predetermined concave portion of the concavo-convex anode electrode portion is shielded from the discharge space. The self-bias voltage of the alternating power is changed by moving the anode area adjusting member having the function of changing the exposed area of the predetermined concave portion of the uneven anode electrode section in the discharge space to change the area of the anode electrode. Is a sputtering method having a step of adjusting
According to the present invention, the anode self-bias voltage of the alternating electric power is made constant by moving the anode area adjusting member so as to increase the exposed area of a predetermined concave portion of the uneven anode electrode section in the discharge space. This is a controlled sputtering method.
The present invention is the sputtering method, wherein the alternating power supplied between the cathode electrode and the anode electrode is high frequency power or pulsed DC power.
The present invention provides a vacuum chamber having a discharge space, an alternating power source for supplying alternating power between a target and an anode electrode via a cathode electrode in the vacuum chamber, and a vacuum chamber provided in the vacuum chamber, A concave portion in the portion, and the concave and convex anode electrode portion of the concave and convex structure that becomes the same potential as the anode electrode during sputtering, and provided on the discharge space side with respect to the concave and convex anode electrode portion in the vacuum chamber, While having a potential equivalent to that of the anode electrode during sputtering, it has a shield portion that shields the concave portion of the uneven anode electrode portion with respect to the discharge space, and an exposed portion that exposes the concave portion with respect to the discharge space, An anode area adjusting member configured to adjust the exposed area of the concave portion of the concave and convex anode electrode portion by changing the positional relationship between the shielding portion and the exposed portion and the concave portion of the concave and convex anode electrode portion due to the movement; The sputtering apparatus includes a drive unit that drives the anode area adjusting member to move the anode area adjusting member in a predetermined direction.
According to the present invention, the uneven anode electrode portion has a plurality of recesses, and a plurality of anode area adjusting holes formed in a shape corresponding to the shape of the recesses of the uneven anode electrode portion are provided as exposed portions of the anode area adjusting member. It is a sputtering device that has.
The present invention is the sputtering apparatus in which the opening of the concave portion of the uneven anode electrode portion and the anode area adjusting hole of the anode area adjusting member are formed in a circular shape.
According to the present invention, a plurality of concave portions are arranged in a predetermined circle on the uneven anode electrode portion, and a plurality of anode area adjusting holes of the anode area adjusting member correspond to the concave portions of the uneven anode electrode portion, respectively. In the sputtering device, the anode area adjusting member is configured to rotate about the circle in which the plurality of concave and convex portions of the uneven anode electrode portion are arranged.
The present invention has, as the concave portions of the concave-convex anode electrode portion, a plurality of substrate-side concave portions provided on the side closer to the substrate that is the film formation target and a plurality of outer concave portions provided outside the substrate-side concave portions. The anode area adjusting hole of the anode area adjusting member is provided at a position corresponding to the concave portion on the substrate side of the uneven anode electrode portion.

According to the present invention, the concave and convex portions of the concave and convex anode electrode portion having the concave and convex structure having the same potential as the anode electrode during the sputtering are arranged in the discharge space toward the discharge space side, and the concave and convex anode electrode portion is formed with respect to the discharge space. By moving the anode area adjusting member having a function of shielding the predetermined concave portion of, and changing (for example, increasing) the area of the anode electrode by changing the exposed area of the predetermined concave portion of the uneven anode electrode portion in the discharge space, By adjusting the self-bias voltage of the alternating electric power to increase, for example, when forming an insulating film such as an oxide or nitride for a long time by sputtering using high frequency electric power, the alternating electric The self-bias voltage of electric power can be returned to the initial state of film formation to keep the film formation rate constant.

Sectional drawing which shows the structure of embodiment of the sputtering apparatus which concerns on this invention. (A)-(c): It shows an example of the uneven anode electrode portion used in the present invention, FIG. 2(a) is a plan view, and FIG. 2(b) is a sectional view taken along line AA of FIG. 2(a). 2(c) is a sectional view taken along line BB of FIG. 2(a). 3A and 3B show examples of the anode area adjusting member used in the present invention, FIG. 3A is a plan view, and FIG. 3B is a sectional view taken along line CC of FIG. 3A. (A) and (b): Plan views showing an example of the operation of the present embodiment and the operation of the present invention (No. 1) (A) and (b): Plan views showing an example of the operation of the present embodiment and the operation of the present invention (No. 2)

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

2A to 2C show an example of the uneven anode electrode portion used in the present invention. FIG. 2A is a plan view and FIG. 2B is A-A in FIG. 2A. 2C is a sectional view taken along line BB in FIG. 2A.

3(a) and 3(b) show an example of the anode area adjusting member used in the present invention. FIG. 3(a) is a plan view and FIG. 3(b) is a line C-C in FIG. 3(a). FIG.

As shown in FIG. 1, the sputtering apparatus 1 of the present embodiment has a vacuum chamber 2 in which the substrate 20 is placed on the mounting surface 2S of the stage 2a.

The vacuum chamber 2 is connected to a vacuum exhaust device (not shown), is configured to introduce a process gas such as argon gas, and is grounded. Therefore, this vacuum chamber 2 serves as an anode electrode.

In the case of the present embodiment, the stage 2a in the vacuum chamber 2 is electrically connected to the vacuum chamber 2 and is set to the ground potential, and functions as an anode electrode. The stage 2a may have a floating potential.

A target 4 held by a backing plate 3 as a cathode electrode is provided in a portion of the vacuum chamber 2 facing the mounting surface 2S of the stage 2a.

Then, the high frequency power supply 5 provided outside the vacuum chamber 2 supplies high frequency power to the target 4 via the backing plate 3.

In the present embodiment, the backing plate 3 is electrically insulated from the vacuum chamber 2 by the flange member 6 surrounding the backing plate 3 and made of an insulating material.

A known magnet device 7 for magnetron sputtering is provided on the back side of the backing plate 3.
On the other hand, an uneven anode electrode portion 8 is provided near the stage 2a in the vacuum chamber 2.

As shown in FIGS. 1 and 2(a), the uneven anode electrode portion 8 of this example is formed in a cylindrical shape having a through hole 8A in the central portion, and the inner edge portion of the through hole 8A surrounds the stage 2a. It is provided so as to be close to and surround the stage 2a.

In this example, the mounting surface 2S of the stage 2a (the surface facing the target 4) is formed in a flat shape, and the surface of the uneven anode electrode portion 8 on the side of the discharge space (hereinafter, referred to as “discharge space side surface”). .) 8S is also formed in a planar shape.

The uneven anode electrode portion 8 is made of, for example, aluminum, is electrically connected to the vacuum chamber 2 and is set to the ground potential, and serves as an anode electrode.

Then, the discharge space side surface 8S of the uneven anode electrode portion 8 is provided, for example, substantially flush with the mounting surface 2S of the stage 2a, and a bottomed, for example, cylindrical concave portion 80 is formed on the discharge space side surface 8S. It is provided (see FIG. 2B).

Here, the concave portion 80 of the concave-convex anode electrode portion 8 includes the substrate-side concave portion 8a provided on the through hole 8A side, that is, the stage 2a side on which the substrate 20 is mounted, and the outer concave portion 8b provided outside the substrate-side concave portion 8a. And have.

The substrate-side recessed portion 8a and the outer recessed portion 8b of this example are each formed in a shape extending in a direction toward the target 4, that is, for example, perpendicularly to the discharge space side surface 8S of the uneven anode electrode portion 8.

The substrate-side recessed portion 8a and the outer recessed portion 8b are arranged concentrically with a predetermined distance from the center point O of the circular surface of the uneven anode electrode portion 8 on the discharge space side.

In this example, the size and number of the substrate-side recesses 8a are set so that the distance between the adjacent substrate-side recesses 8a is larger than the diameter of each opening.

As shown in FIG. 1, an anode area adjusting member 9 is provided near the discharge space side surface 8S of the uneven anode electrode portion 8 in the vacuum chamber 2.

The anode area adjusting member 9 is made of, for example, a metal material such as aluminum or an inorganic material such as ceramics. The anode area adjusting member 9 does not need to be electrically connected to the uneven anode electrode portion 8 and may be set to a floating potential.

The anode area adjusting member 9 of this example has a hole 9A having an inner diameter larger than the outer diameter of the stage 2a, and a ring-shaped flat plate having an outer diameter smaller than the outer diameter of the discharge space side surface 8S of the uneven anode electrode portion 8. It is composed of members.

Further, the outer diameter of the anode area adjusting member 9 of this example is set so that it does not overlap with the outer recesses 8b of the uneven anode electrode portion 8 (see FIG. 1 and FIG. 4A described later). ..

In the present example, the outer diameter of the anode area adjusting member 9 is set to such a size because the substrate 20 is larger than the region apart from the substrate 20 with respect to the discharge space side surface 8S of the uneven anode electrode portion 8. The anode area in the region close to the substrate 20 is increased in consideration of the fact that a film by sputtering is easily deposited in the close region.

The anode area adjusting member 9 is arranged in parallel to the discharge space side surface 8S of the uneven anode electrode portion 8 and concentrically with the uneven anode electrode portion 8.

As shown in FIGS. 3A and 3B, the anode area adjusting member 9 has a circle centered on the center point O of the ring, that is, the center point O of the circular surface on the discharge space side of the uneven anode electrode portion 8. Is provided with a plurality of circular anode area adjustment holes 9a (exposed portions).

Further, a portion of the anode area adjusting member 9 where the anode area adjusting hole 9a is not provided has a shielding portion 9B having a function of shielding the substrate-side concave portion 8a of the uneven anode electrode portion 8 from the discharge space in the vacuum chamber 2. Is provided.

In this example, the anode area adjusting hole 9a of the anode area adjusting member 9 has the same diameter as the substrate-side concave portion 8a of the uneven anode electrode portion 8 and has the same diameter as the substrate-side concave portion 8a of the uneven anode electrode portion 8. A plurality of anode area adjusting holes 9a are provided at equal intervals.

In the case of the present invention, although not particularly limited, from the viewpoint of improving the adjustment efficiency of the anode area, the area of the anode area adjusting hole 9a of the anode area adjusting member 9 is set to be the substrate-side concave portion 8a of the uneven anode electrode portion 8. It is preferable to set each diameter so as to be equal to or larger than the area.

Specifically, when the diameter is about 5 mm or less, the substrate-side concave portion 8a of the uneven anode electrode portion 8 and the anode area adjusting hole 9a of the anode area adjusting member 9 do not pass plasma and serve as the anode electrode. Since it will not function, it is necessary to set each diameter to 6 mm or more, and a more preferable diameter is 10 mm or more.

The anode area adjusting member 9 is connected to a motor 30 that is a drive source provided outside the vacuum chamber 2 (see FIG. 1), and is centered on the center point O of the discharge space side surface 8S of the uneven anode electrode portion 8 described above. It is configured to rotate and move in the direction of by a predetermined angle.

4(a)(b) to FIG. 5(a)(b) are plan views showing an example of the operation of the present embodiment and the operation of the present invention.

In the case where the insulating film is formed by sputtering in the present embodiment, the anode area adjusting hole 9a of the anode area adjusting member 9 is uneven as shown in FIG. The anode electrode portion 8 is arranged at a position where it does not overlap the substrate-side concave portion 8a.

As a result, the substrate-side concave portion 8a of the uneven anode electrode portion 8 is shielded from the discharge space by the shield portion 9B of the anode area adjusting member 9.

On the other hand, the discharge space side surface 8S of the uneven anode electrode portion 8 is exposed inside the anode area adjustment hole 9a of the anode area adjustment member 9, and the discharge space side surface 8S faces the surface of the target 4.

When film formation is performed by sputtering for a while in this state, an insulating film is deposited on the surface of the uneven anode electrode portion 8 and the surface of the anode area adjusting member 9, and the area of the entire anode electrode is reduced, which reduces the film formation rate. To do.

In that case, the motor 30 shown in FIG. 1 is operated, and as shown in FIG. 4B, the anode area adjusting member 9 is rotationally moved around the center point O so that the anode area adjusting hole 9a has the uneven anode electrode. It is arranged to partially overlap the opening of the substrate-side recess 8a of the portion 8.

As a result, the inner surface of each substrate-side concave portion 8a of the uneven anode electrode portion 8 is partially exposed via each anode area adjusting hole 9a of the anode area adjusting member 9, and as a result, the area of the uneven anode electrode portion 8 increases. As a result, the area of the entire anode electrode increases.

In this case, control is performed so that the inner surface of each substrate-side concave portion 8a of the uneven anode electrode portion 8 is exposed so that the self-bias potential (Vdc) of the high-frequency power supplied to the target 4 becomes equal to the initial value of sputtering. Good to do.

The angle at which the anode area adjusting member 9 is rotated can be determined by measuring the self-bias potential of the high frequency power supplied to the target 4.

Further, the self-bias potential of the high frequency power supplied to the target 4 in the process is measured in advance, and the anode area adjusting member 9 is rotated by a predetermined angle at a predetermined timing based on the obtained result. You can also

After that, when film formation by sputtering is continued, an insulating film is deposited on the surface of the uneven anode electrode portion 8 and the surface of the anode area adjusting member 9, the area thereof is reduced, and the film formation speed is reduced.

In this case, the motor is operated again, and as shown in FIG. 5A, the anode area adjusting member 9 is rotationally moved about the center point O to form the anode area adjusting hole 9a and the substrate of the uneven anode electrode portion 8 on the substrate. The self-bias potential of the high-frequency power supplied to the target 4 by the above-described method is made equal to the initial value of sputtering by increasing the area overlapping the opening of the side recessed portion 8a to increase the exposed area of the uneven anode electrode portion 8. Control to be.

The example shown in FIG. 5B shows a case where the anode area adjusting hole 9a of the anode area adjusting member 9 completely overlaps with the opening of the substrate-side concave portion 8a of the uneven anode electrode portion 8. This is the case where the area of the entire electrode is maximum.

In the present embodiment described above, the uneven anode electrode portion 8 having the uneven structure having the same potential as the anode electrode at the time of sputtering is arranged in the discharge space, and the substrate side concave portion 8a of the uneven anode electrode portion 8 with respect to the discharge space. The anode area adjusting member 9 having the shielding portion 9B for shielding the discharge area and the anode area adjusting hole 9a for exposing the substrate side concave portion 8a to the discharge space is rotationally moved to form the concave and convex anode electrode portion 8 in the discharge space on the substrate side. By adjusting the exposed area of 8a and increasing the area of the anode electrode, the self-bias voltage (Vdc) of the high frequency power is adjusted to increase the insulation of oxides, nitrides, etc. by sputtering using the high frequency power. When forming a film for a long period of time, if the film forming rate is lowered, the self-bias voltage of the high frequency power can be returned to the initial state of the film forming to keep the film forming rate constant.

The present invention is not limited to the above embodiment, and various changes can be made. For example, in the above embodiment, the uneven anode electrode portion 8 is provided around the stage 2a in the vacuum chamber 2, and the anode area adjusting member 9 is arranged near the uneven anode electrode portion 8 on the discharge space side. However, the present invention is not limited to this, and as long as it has the same configuration including the uneven anode electrode portion 8 and the anode area adjusting member 9 of the above-described embodiment, it may be provided near the target 4 in the discharge space. Alternatively, it may be arranged between the target 4 and the stage 2a.

Here, when the uneven anode electrode portion 8 and the anode area adjusting member 9 are provided in the vicinity of the target 4, the substrate side concave portion 8a of the uneven anode electrode portion 8 is directed to the discharge space side and the anode area adjusting member 9 is uneven. It may be arranged on the discharge space side with respect to the anode electrode portion 8.

Further, in the above-described embodiment, the concave and convex anode electrode portion 8 is provided with the concave portion 80 having a circular opening (the substrate side concave portion 8a), and the anode area adjusting member 9 is provided with the circular anode area adjusting hole 9a as the exposed portion. Although the present invention is not limited to this, the openings of the concave-convex anode electrode portion 8 on the substrate side and the anode area adjusting hole 9a of the anode area adjusting member 9 may be provided in various shapes (elliptical shape, polygonal shape). , Oblong hole shape) can be adopted, and the number thereof can be appropriately changed.

Further, the anode area adjusting member 9 may be provided with notches as the exposed portions instead of the holes.

Further, in the above-described embodiment, the exposed area of the substrate-side concave portion 8a provided in the uneven anode electrode portion 8 is changed by the rotational movement of the anode area adjusting hole 9a provided in the anode area adjusting member 9. The area adjusting member 9 may be configured to change the exposed area of the substrate-side concave portion 8a provided in the uneven anode electrode portion 8 by moving in a linear or curved manner.

Furthermore, although cases have been described with the above embodiment as examples where sputtering is performed using high-frequency power, the present invention is not limited to this, and sputtering is performed using pulsed DC power having a frequency of 10 kHz or higher, for example. It can also be applied in cases.

When such pulsed DC power is used, the frequency of the power supplied is smaller than when high frequency power is used, and the increase rate of impedance with respect to the thickness of the insulating film deposited on the anode electrode is large.

That is, when the frequency of the power to be supplied is smaller than when high-frequency power is used as in the case of using pulsed DC power, even if the insulating film deposited on the anode electrode is thin, the film of the above-mentioned insulating film is formed. Since the impedance with respect to the thickness is relatively large, the area of the anode electrode is likely to be smaller than when high frequency power is used, and as a result, the effect of adjusting the anode electrode area according to the present invention tends to be more remarkable.

1... Sputtering device 2... Vacuum chamber (anode electrode)
2a... Stage (anode electrode)
3... Backing plate (cathode electrode)
4... Target 5... High-frequency power source 8... Concavo-convex anode electrode portion 8a... Substrate side concave portion 8b... Outer concave portion 8S... Discharge space side surface 9... Anode area adjusting member (shielding means)
9a... Anode area adjusting hole (exposed part)
9B... Shielding section 20... Substrate 30... Motor (driving section)

Claims (8)

A sputtering method in which alternating electric power is supplied between a cathode electrode and an anode electrode in a vacuum to cause discharge in a discharge space, and a target is sputtered to form an insulating film on a substrate.
An uneven anode electrode portion having an uneven structure having the same potential as the anode electrode during sputtering is arranged in the discharge space,
By moving an anode area adjusting member having a function of shielding a predetermined concave portion of the concave-convex anode electrode portion with respect to the discharge space, and changing an exposed area of the predetermined concave portion of the concave-convex anode electrode portion in the discharge space, A sputtering method comprising the step of adjusting the self-bias voltage of the alternating electric power by changing the area of the anode electrode. The self-bias voltage of the alternating electric power is controlled to be constant by moving the anode area adjusting member so as to increase an exposed area of a predetermined concave portion of the uneven anode electrode portion in the discharge space. 1. The sputtering method according to 1. The sputtering method according to claim 1, wherein the alternating power supplied between the cathode electrode and the anode electrode is high-frequency power or pulsed DC power. A vacuum chamber having a discharge space,
An alternating power source for supplying alternating power between the target and the anode electrode via the cathode electrode in the vacuum chamber,
A concave-convex anode electrode portion provided in the vacuum chamber, having a concave portion on the discharge space side, and having a concave-convex structure having a potential equivalent to that of the anode electrode during sputtering,
It is provided on the discharge space side with respect to the uneven anode electrode portion in the vacuum chamber, has a potential equal to that of the anode electrode during sputtering, and shields the concave portion of the uneven anode electrode portion with respect to the discharge space. The uneven anode electrode has a shield portion and an exposed portion that exposes the concave portion with respect to the discharge space, and the movement of the shield portion and the exposed portion changes the positional relationship between the concave portion and the concave portion of the uneven anode electrode portion. An anode area adjusting member configured to adjust the exposed area of the concave portion of the portion,
A sputtering apparatus comprising: a drive unit that drives the anode area adjustment member to move it in a predetermined direction. 5. The uneven anode electrode section has a plurality of recesses, and the anode area adjusting member has a plurality of anode area adjusting holes formed in a shape corresponding to the shape of the recesses of the uneven anode electrode section as exposed portions. The sputtering apparatus described. The sputtering device according to claim 4, wherein the opening of the concave portion of the uneven anode electrode portion and the anode area adjusting hole of the anode area adjusting member are formed in a circular shape. A plurality of concave portions are arranged in a predetermined circle on the uneven anode electrode portion, and a plurality of anode area adjusting holes of the anode area adjusting member are provided at positions corresponding to the concave portions of the uneven anode electrode portion. The sputtering apparatus according to any one of claims 4 to 6, wherein the anode area adjusting member is configured to rotate around the circle in which the plurality of recesses of the uneven anode electrode portion are arranged. As the recesses of the uneven anode electrode portion, there are a plurality of substrate-side recesses provided on the side close to the substrate that is the film formation target, and a plurality of outer recesses provided outside the substrate-side recesses. 8. The sputtering apparatus according to claim 4, wherein the anode area adjusting hole of the area adjusting member is provided at a position corresponding to the concave portion on the substrate side of the uneven anode electrode portion.

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