JPH10176267A - Sputtering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sputtering device by which formation of a dust generating source is suppressed at the time of executing a film-forming treatment by collimation sputtering. SOLUTION: The sputtering device 10 is provided with an upper shield 62 and an intermediate shield 70 of tube shape respectively between a target 14 and a collimator and between the collimator and a pedestal 16. By this constitution, formation of shadow part with respect to the target 14 is suppressed and thereby possibility of formation of a film which is easily dust generating, of low density and fragile by sputtering particles losing directivity after passing through the collimator 48 is low. Further the intermediate shield 70 is inclined inward and the sputtering particles passing through the collimator 48 and having high directivity directly stick to an inner peripheral wall thereof to form a hardly dusting and dense film. By the same reason, an outer peripheral wall of an annular clasp ring 66 clasping a semiconductor wafer 18 on the pedestal 16 is inclined outward.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering apparatus, and more particularly to a means for suppressing dust generation inside the apparatus.

[0002]

2. Description of the Related Art With the recent progress of high integration and miniaturization of semiconductor devices, multilayer wiring structures have been rapidly adopted in the field of metal wiring forming technology. For example, when an aluminum film is used as a wiring layer, a titanium nitride (TiN) film is generally formed as a base layer.

[0003] Film formation of TiN is usually performed using a reactive sputtering technique. That is, a mixed gas of argon (Ar) and nitrogen (N ₂ ) is introduced into the vacuum chamber,
Ti sputtered from a titanium (Ti) target
Reacts with N ₂ in the processing chamber to form TiN;
This TiN is deposited on a semiconductor wafer to form a film.

In the metal wiring forming technique, a method called a collimator, which is provided with a number of holes called a collimator between a target and a semiconductor wafer to form a film, is used. In this collimation sputtering method, the sputtered particles, which are originally non-directional, have directivity by passing the sputtered particles through the holes of the collimator. As a result, only the vertical component sputter particles are mainly deposited on the semiconductor wafer, so that a sufficient bottom coverage rate required with recent thinning of design rules is secured.

[0005]

However, in the conventional configuration, since the collimator is provided in the vacuum chamber, a portion where directional sputtered particles reach only by diffusion (hereinafter referred to as a "shadow portion") is inside the vacuum chamber. Will be present. In this shadow portion, the directional sputtered particles that have passed through the collimator do not directly adhere with high energy, but adhere with low energy due to gas diffusion in the vacuum chamber.

In the vacuum chamber, a cylindrical shield is provided for preventing sputter particles from adhering to the inner wall of the chamber, and a clamp ring is provided for holding a semiconductor wafer. However, in conventional shields and clamp rings, since the inner wall surface of the shield and the outer wall surface of the clamp ring are substantially parallel to the direction in which the sputtered particles travel, there are portions where only low-energy sputtered particles adhere like shadows. I do.

[0007] For this reason, the surface diffusion caused by the interaction between the adhering particles and the flying particles on the surface perpendicular to the target on the shadow portion, the inner wall surface of the shield below the collimator, and the outer wall surface of the clamp ring is hardly caused. Since they do not, the density of the films formed on them is very low. Such a low-density film has a small adhesive force and is easily peeled. For this reason, in the vacuum chamber, this film becomes a dust generation source, and may be a contaminant when performing another processing of the semiconductor wafer.

Accordingly, an object of the present invention is to provide a sputtering apparatus characterized by the shape of a shield that suppresses the formation of a dust source as described above when performing a film forming process by collimation sputtering. I do.

[0009]

According to the present invention, there is provided a sputtering apparatus, comprising: a vacuum chamber, a pedestal for supporting a substrate in the vacuum chamber, and a surface of the substrate supported by the pedestal. And a target from which particles are emitted by sputtering, a disk-shaped collimator disposed between the pedestal and the target, and having a number of holes formed to selectively pass particles from the target. In the sputtering apparatus having, between the target and the collimator,
A cylindrical shield for protecting the inner wall of the vacuum chamber is provided, and the inner edge of the lower end of the shield is located outside the outer edge of the collimator. The presence of this shield substantially eliminates the existence of shadows, so that the formation of the above-mentioned dust source is suppressed and the TiN particles are removed from the holes 50 of the disc-shaped plate 52.
, And diffuses above the support ring 58 and does not adhere to the inner wall surface of the vacuum chamber.

[0010] Further, another cylindrical shield is provided between the collimator and the pedestal to suppress diffusion of particles from the target passing through the collimator, and the inner edge of the upper end of the shield is formed outside the collimator. It is characterized in that it is arranged inside the periphery. Due to the characteristics of this shield, the formation of a dust generation source is suppressed without generating a shadow portion. Further, the inner diameter of the shield may be reduced from the collimator toward the pedestal so that particles from the target directly adhere and cause surface diffusion. Specifically, the inner wall surface of the shield is tapered,
Preferably, the taper angle is in the range of 5 ° to 15 °.

Further, the sputtering apparatus of the present invention may be provided with a clamp ring for gripping a peripheral portion of the substrate supported by the pedestal in cooperation with the pedestal. The outer diameter of the clamp ring may be increased from the collimator toward the pedestal for the same reason that the diameter is reduced toward the pedestal. Specifically, the outer wall surface of the clamp ring is tapered, and the taper angle is preferably set to 20 ° or more.

When the collimator is larger than the pedestal, it is inevitable that the back surface of the collimator becomes a shadow, and a shadow is remarkably formed on the collimator. In such a case, the collimator may be coaxially opposed to the pedestal and have a diameter substantially equal to the substrate supported by the pedestal, and a gap may be formed between the collimator and the vacuum chamber. This reduces shadows in the collimator. The gap may be formed by supporting the collimator with respect to the vacuum chamber by a plurality of radially arranged arms. Alternatively, the arm may be provided integrally on the outer peripheral surface of the collimator.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals.

FIG. 1 is a side sectional view showing a sputtering apparatus 10 to which the present invention is applied. This sputtering apparatus 10
It is for forming a TiN film, and includes a vacuum chamber 12 and a target 14 made of Ti disposed in an upper opening of the vacuum chamber 12. Inside the vacuum chamber 12, a pedestal 16 serving as a substrate supporting means is arranged coaxially with the target 14. The pedestal 16 is configured to support a semiconductor wafer 18 which is a substrate to be processed on an upper surface thereof. Further, the pedestal 16 is made of a conductive material, and preferably has a high compatibility with the TiN film forming process.
Made from i. A drive shaft 20 having an elevating mechanism (not shown) is connected to the lower surface of the pedestal 16 in a state protected by a bellows 22, so that the pedestal 16 can move up and down.

The vacuum chamber 12 basically includes a chamber main body 24 made of a conductive material and a process kit disposed on the chamber main body 24. The process kit includes an annular lower adapter 28 detachably attached to an upper flange 26 of the chamber main body 24, and an annular upper adapter 30 detachably attached to the upper surface of the lower adapter 28. These adapters 28, 30
Is made of a conductive material and is usually made of stainless steel, aluminum (Al), Ti or the like. A peripheral flange 34 of the target 14 is placed on an upper surface of the upper adapter 30 via an insulating ring 32 made of quartz, alumina, or the like, and is detachably fixed.

As shown in FIG. 2, an Ar gas supply source 36 and a N ₂ gas supply source 38 are connected to the vacuum chamber 12 as process gas supply means. Vacuum pump 4 for
0 is connected. An O-ring may be provided between the members to keep the vacuum chamber 12 airtight.

In the target 14 which is insulated from the chamber main body 24 and the like by the insulating ring 32, as shown in FIG.
Are connected by an electric wiring 46 interposed therebetween, and the positive terminal of the DC power supply is connected to the vacuum chamber 12 and grounded.

The process kit of the illustrated embodiment has a collimator 48. The collimator 48 is of a conventionally known type. That is, a disc-shaped plate 5 made of Ti having holes 50 having a hexagonal cross section arranged in a honeycomb shape.
The support frame 54 is attached to the outer peripheral portion of the second member 2. The collimator 48 is supported by a support ring 58 made of a conductive material such as stainless steel, Al or Ti mounted on an inner flange 56 projecting inward from the inner peripheral surface of the lower adapter 28. More specifically, the collimator 48 is mounted on the protrusion 60 extending inward from the lower edge of the inner peripheral surface of the support ring 58 in parallel and coaxially with the target 14 and the pedestal 16. This allows the target 14 and the pedestal 16 to be arranged parallel and coaxial with them.

The process kit is provided with a cylindrical upper shield 62 and a cylindrical lower shield 64 in order to prevent the inner wall surface of the vacuum chamber 12 from being coated with sputter particles. These shields 6
2, 64 are made of a conductive material, preferably made of Ti.

Basically, the upper shield 62 is for protecting the inner wall surface of the chamber between the upper adapter 30 and the collimator 48. Referring to FIG.
The upper edge of the upper shield 62 is screwed to the lower surface of the upper adapter 30, and the lower edge of the upper shield 62 extends near the upper surface of the collimator 48 while being separated from the collimator with a certain gap. , The upper shield 62 surrounds the target 14.

The lower shield 64 is basically for protecting the inner wall surface of the chamber between the pedestal 16 and the collimator 48 at the position where the film can be formed by raising the shield. Referring to FIG. 1, the lower shield 6
4 is screwed to the lower surface of the support ring 58 and extends around the pedestal 16 so as to surround the collimator 48 and is raised to a position where it can be processed. The free edge of the lower shield 64 is folded upward so that it supports the clamp ring 66 when the pedestal 16 is lowered. Clamp ring 6
6 moves the semiconductor wafer 18 to the pedestal 16 when the pedestal 16 is raised during processing of the semiconductor wafer 18.
The pressure is uniformly applied to the back surface of the wafer 18 for gas heating. Also,
An opening 68 is provided above the lower shield 64, and the lower shield 64 is
The space surrounding is evacuated.

In order to protect the shadow formed on the lower part of the support ring 58 in the lower shield 64,
A cylindrical intermediate shield 70 is provided between the collimator and the pedestal. The intermediate shield 70 is screwed at the same position as the lower shield 64 with the outward flange 74 extending outward from the upper peripheral edge thereof.
It is supported on a support ring 58.

As understood from the above description, the chamber body 24, the upper and lower adapters 28 and 30, the collimator 48, the upper and lower shields 62 and 64, and the intermediate shield 7
0 and the support ring 58 are electrically connected to each other. On the other hand, the pedestal 16 is electrically insulated from the chamber main body 24.

When a TiN film is formed on the surface of the semiconductor wafer 18 by the reactive sputtering method in the sputtering apparatus 10 having such a configuration, first, the vacuum pump 40 is operated to evacuate the inside of the vacuum chamber 12 to a predetermined vacuum degree. After reducing the pressure to a predetermined flow rate, Ar gas and N ₂ gas are supplied from the Ar gas supply source 36 and the N ₂ gas supply source 38 to form a mixed gas,
It is introduced into the vacuum chamber 12. Next, the semiconductor wafer 18 is placed on the upper surface of the pedestal 16, and the pedestal 16 is lifted and arranged at the processing position. When the switch is closed and the DC power supply 42 is turned on to apply a negative bias to the target 14, plasma is generated between the target 14 and the pedestal 16, more specifically, between the target 14 and the collimator 48. Generated and positive Ar ions in the plasma cause the target 14 to be negatively charged.
Shock. When Ar ions collide with the target 14, the target atoms from the target 14, that is, Ti
Particles are ejected. This Ti reacts with N ₂ in the vacuum chamber 12 to become TiN, and is deposited on the semiconductor wafer 18 to form a TiN film.

In this film forming process, the target 1
Since the grounded collimator 48 is arranged between the pedestal 4 and the pedestal 16, only the TiN particles traveling from the target 14 toward the pedestal 16 in the substantially vertical direction are disc-shaped plates of the collimator 48. 5
2 through hole 50. Therefore, when the TiN particles are deposited on the semiconductor wafer 18 to form a film, the bottom coverage ratio of the wafer is increased.

On the other hand, TiN particles other than the vertical component adhere to the upper surface of the disk-shaped plate 52 and the inner surface 51 of the hole 50 to form a TiN film. Also, TiN particles passes through the disk-like plate 52 loses directivity by collision with Ar and N _2, which may be diffuse.

In the sputtering apparatus 10 of the present embodiment, FIG.
Since the lower edge of the upper shield 62 extends to the peripheral edge of the upper surface of the support frame 54 of the collimator 48, no shadow is formed on the upper surface of the collimator 48, as shown in FIG. Further, the TiN particles do not pass through the holes 50 of the disk-shaped plate 52 and diffuse above the support ring 58.
Therefore, formation of a dust generation source is suppressed. The position of the lower edge of the upper shield 62 is not limited to that shown in FIG.
If the support frame 54 is provided outside the peripheral edge of the upper surface of the support frame 54, no shadow portion is formed on the upper surface of the collimator 48. Also, the intermediate shield 70 is provided so that the inner diameter of the shield is smaller than the outer diameter of the disc-shaped plate 52 as clearly shown in FIG. 1 so that no shadow is formed on the inner wall surface.

By the way, some of the directional TiN particles that have passed through the collimator 48 do not contribute to the film formation. In the present embodiment, as shown in FIG. 1, the wall of the intermediate shield 70 is formed as an inwardly inclined surface 72 that extends inwardly below the lower peripheral edge of the support frame 54 of the collimator 48. Therefore, the directional, high-energy TiN particles that have passed through the collimator 48 are directly adhered with some directivity remaining.

The taper angle (θ) of the inwardly inclined surface 72 inclined inwardly with respect to the vertical surface as shown in FIG. 1 is determined by the thickness of the disk-shaped plate 52 through which sputtered particles pass. And the size of the hole 50. When a normal collimator is used, the value is 5 ゜ to 15１５.
It is preferable to be within the range of ゜. In the illustrated embodiment, the lower edge of the intermediate shield 70 is preferably provided at a position lower than the opening 68 of the lower shield 64 in order to optimize the conductance in the lower shield 64 during evacuation.

For the same reason that the inwardly inclined surface 72 of the intermediate shield 70 is configured as described above, the outer peripheral surface of the clamp ring 66 has an outwardly inclined surface 76 that is downwardly outwardly inclined. Is provided. Also for the outwardly inclined surface 76, the taper angle (φ) inclined outwardly with respect to the vertical surface is determined by the thickness of the disk-shaped plate 52 through which sputtered particles pass, the size of the hole 50, and the like. When a well-known collimator is used, its value is preferably set to 20 ° or more. Also, the clamp ring 66
In consideration of only the replacement, it is preferable that the inner diameter of the lower edge of the inwardly inclined surface 72 of the intermediate shield 70 be larger than the outer diameter of the lower edge of the outwardly inclined surface 76 of the clamp ring 66.

As described above, the TiN particles have the inwardly inclined surface 7.
The TiN film formed is dense because it can directly adhere to the second and outward inclined surfaces 76 and sufficiently diffuse the surface. Therefore, in the vacuum chamber 12, the formation of a low-density and fragile film, which is easily peeled off, is suppressed, and contaminant particles do not occur in other processes.

The sputtering apparatus of the present invention is not limited to the above. For example, when the diameter of the semiconductor wafer is significantly smaller than the outer diameter of a normal collimator, the shadow portion may increase on the lower surface of the collimator. In such a case, in the present embodiment, the collimator is defined as a portion which substantially contributes to film formation on the semiconductor wafer and a portion which does not, so that the shadow portion is reduced as much as possible. That is, as shown in FIG. 3, the outer peripheral wall of the support frame 54 attached to the outer periphery of the disk-shaped plate 52 having the same outer diameter as the wafer has the shape arranged at equal intervals in the circumferential direction. The one integrally connected to the annular external support frame 55 via the arm 53 having the same size is the collimator 48 of the present embodiment.

When this collimator 48 is provided in the sputtering apparatus 10 shown in FIG. 1, a gap 57 is formed between the disc-shaped plate and the external support frame 55, so that the sputtering film forming process is performed. In this case, almost no shadow is formed. Further, the sputtered particles having no directivity passing through the gap 57 hardly contribute to the film formation of the semiconductor wafer 18, and the lower shield 64 and the intermediate shield 7 do not contribute to the film formation.
Directly adheres to 0 etc. Therefore, in this embodiment, even if the collimator shown in FIG. 3 is used, the formation of the above-mentioned dust source is suppressed. The above-described gap may be filled in the lower surface of the collimator in which the outer diameter of the disk-shaped plate 52 is substantially the same as the outer diameter of the semiconductor wafer 18 so that the shadow portion is reduced as much as possible.
As described above, to make the disk-shaped plate 52 and the semiconductor wafer 18 the same size, it is necessary that the sputtering apparatus 10 according to the present embodiment allows the target 14 to be sputtered uniformly.
This is effective when applied to a magnetron sputtering device.

Although the preferred embodiments of the present invention have been described in detail, it goes without saying that the present invention is not limited to the above embodiments. For example, in the above embodiment, the target of peeling prevention is the TiN film, but it is also possible to prevent peeling of a film made of another material, for example, tungsten. The sputtering method is magnetron sputtering,
It is not limited to the above, as long as high-frequency sputtering or any other method is used in which the target atoms are emitted by colliding particles with the target.

[0035]

As described above, the sputtering apparatus of the present invention prevents sputter particles from the target from adhering to the shadow portion, and forms a high-density dense film without peeling. ing. With this, when the film formed by sputtering becomes a contaminant in another process,
Since it does not become a source of dust that is peeled off and diffused, the yield of semiconductor devices as final products is improved.

Further, it is possible to carry out the film forming process for a long time without replacing the shields. That is, when replacing the shields, it is necessary to open the vacuum chamber, and it takes a considerable time to reduce the pressure inside the chamber to a predetermined degree of vacuum again. Although the production efficiency is reduced, according to the present invention, since the number of replacements of the shields is reduced, productivity and cost of ownership are significantly improved.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing one embodiment of a sputtering apparatus of the present invention.

FIG. 2 is a schematic diagram showing a gas system and an electric system of the sputtering apparatus in the embodiment of FIG.

FIG. 3 is a perspective view of a collimator used in another embodiment of the sputtering apparatus of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Sputter apparatus, 12 ... Vacuum chamber, 14 ... Target, 16 ... Pedestal, 18 ... Semiconductor wafer, 2
4 ... chamber body, 28 ... lower adapter, 30 upper adapter, 48 ... collimator, 52 ... disk-shaped plate, 53
... arm, 55 ... outer support frame, 57 ... clearance, 62 ... upper shield, 64 ... lower shield, 66 ... clamp ring, 70 ... intermediate shield, 72 ... inwardly inclined surface, 76 ...
Outward slope.

Claims (15)

[Claims] A vacuum chamber, a pedestal for supporting a substrate in the vacuum chamber, a target provided to face a surface of the substrate supported by the pedestal, and from which particles are emitted by sputtering; A sputter apparatus, which is disposed between the pedestal and the target and has a disk-shaped collimator in which a number of holes are formed so as to selectively pass particles from the target, wherein the target and the collimator Between them, a cylindrical shield for protecting an inner wall of the vacuum chamber is provided, and a lower end inner edge of the shield is arranged outside an outer peripheral edge of the collimator. . 2. A vacuum chamber, a pedestal for supporting a substrate in the vacuum chamber, and a target provided to face a surface of the substrate supported by the pedestal and emitting particles by sputtering, A sputtering apparatus, which is disposed between the pedestal and the target and has a disk-shaped collimator in which a number of holes are formed so as to selectively pass particles from the target, wherein the collimator and the pedestal A cylindrical shield for suppressing the diffusion of particles from the target that has passed through the collimator is provided therebetween,
A sputter apparatus, wherein an inner edge of an upper end of the shield is arranged inside an outer edge of the collimator. 3. The sputtering apparatus according to claim 2, wherein the inner diameter of the shield is reduced from the collimator toward the pedestal. 4. The sputtering apparatus according to claim 2, wherein the inner wall surface of the shield has a tapered shape, and the taper angle is in a range of 5 ° to 15 °. 5. A vacuum chamber, a pedestal for supporting a substrate in the vacuum chamber, a target provided to face a surface of the substrate supported by the pedestal, and from which particles are emitted by sputtering, A sputtering apparatus, which is disposed between the pedestal and the target and has a disk-shaped collimator in which a number of holes are formed so as to selectively pass particles from the target, wherein the collimator and the pedestal A cylindrical shield for suppressing the diffusion of particles from the target that has passed through the collimator is provided therebetween,
An inner diameter of a cylindrical shield is reduced from the collimator toward the pedestal. 6. The sputtering apparatus according to claim 5, wherein the inner wall surface of the shield has a tapered shape, and the taper angle is in a range of 5 ° to 15 °. 7. A vacuum chamber, a pedestal for supporting a substrate in the vacuum chamber, a target provided to face a surface of the substrate supported by the pedestal, and emitting particles by sputtering, A sputtering apparatus provided between the pedestal and the target and having a disk-shaped collimator having a large number of holes formed to selectively pass particles from the target; and a substrate supported by the pedestal. A clamping ring for gripping a peripheral portion of the pedestal in cooperation with the pedestal, and an outer diameter of the clamping ring is increased from the collimator toward the pedestal. 8. The sputtering apparatus according to claim 7, wherein an outer wall surface of the clamp ring has a tapered shape, and a taper angle thereof is 20 ° or more. 9. A vacuum chamber, a pedestal for supporting a substrate in the vacuum chamber, a target provided to face a surface of the substrate supported by the pedestal, and emitting particles by sputtering, A disc-shaped collimator disposed between the pedestal and the target and having a plurality of holes formed to selectively pass particles from the target, wherein the collimator is coaxial with the pedestal. A sputtering apparatus having a diameter substantially equal to a diameter of a substrate supported by the pedestal and opposed to the pedestal, wherein a gap is formed between the collimator and the vacuum chamber. 10. The sputtering apparatus according to claim 9, wherein the collimator is supported by the plurality of radially arranged arms with respect to the vacuum chamber. 11. The sputtering apparatus according to claim 10, wherein said arm is provided integrally on an outer peripheral surface of a collimator. 12. A vacuum chamber, a pedestal for supporting a substrate in the vacuum chamber, a target provided to face a surface of the substrate supported by the pedestal, and emitting particles by sputtering, Disposed between the pedestal and the target,
A disk-shaped collimator having a large number of holes formed to selectively pass particles from the target, and a cylindrical shape provided to protect an inner wall of the vacuum chamber between the target and the collimator. A first shield, a cylindrical second shield provided between the collimator and the pedestal to suppress diffusion of particles from the target that have passed through the collimator, and the pedestal. A clamp ring for gripping a peripheral portion of the substrate supported by the pedestal in cooperation with the pedestal, wherein a lower inner edge of the first shield is disposed outside an outer peripheral edge of the collimator; The inner edge of the upper end of the second shield is disposed inside the outer peripheral edge of the collimator, and the outer diameter of the clamp ring is Sputtering apparatus characterized by towards Isutaru is larger. 13. The sputtering apparatus according to claim 12, wherein an inner diameter of the second shield is reduced from the collimator toward the pedestal. 14. The sputtering apparatus according to claim 12, wherein an inner wall surface of the second shield has a tapered shape, and a taper angle is in a range of 5 ° to 15 °. 15. The sputtering apparatus according to claim 12, wherein an outer wall surface of said clamp ring has a tapered shape, and a taper angle thereof is 20 ° or more.