JP3366391B2 - Sputtering apparatus and sputtering film forming method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for forming various thin films by sputtering in a semiconductor device manufacturing process, and more particularly to a sputtering apparatus and a sputtering film forming method using a collimator.

[0002]

2. Description of the Related Art In a conventional sputtering apparatus, for example, as shown in FIG. 5, an electrode 22 having a target 21 which is a base material of a thin film and an electrode 24 having a wafer 23 which is a substrate for forming a thin film are installed. In the chamber 25, they are opposed to each other at a predetermined interval. Then, the inside of the chamber 25 is evacuated from the exhaust pipe 27 by the vacuum pump 32, Ar gas, for example, is introduced from the gas introduction pipe 26, and a voltage is applied between the electrodes 22 and 24 by the DC power supply 28, for example, and the chamber 25 is It is designed to generate plasma.

In the above sputtering apparatus, when Ar ⁺ ions accelerated in plasma collide with the surface of the target 21, the electrons are neutralized by the field-emitted electrons in the vicinity of the surface to become neutral, but the momentum is preserved as it is. Then, it plunges into the target 21. The ions gradually lose their energy and stop while colliding with atoms and molecules formed inside the target 21 (in the vicinity of the surface). Target 21
The crystal is damaged by the intrusion of foreign particles,
The atoms constituting the crystal lattice repeatedly collide with each other, and finally the surface of the target 21 emits neutral atoms and molecules (hereinafter referred to as sputtered particles) to the outside.

The sputtered particles thus ejected from the surface of the target 21 fly to the wafer 23 on the electrode 24 from a random direction in the chamber 25 and adhere to the wafer 23 to form a thin film. It

By the way, in order to increase the density of semiconductor integrated circuits, multilayer wiring is being advanced. In recent years, due to the miniaturization, contact holes for connecting a semiconductor substrate and metal wiring and wiring of upper and lower layers are formed. Beer holes that connect between the
The aspect ratio (depth / width) is increasing.

However, in the case of forming a thin film on a contact hole or a via hole having a large aspect ratio, the target 21 is used in the above-mentioned sputtering method.
Since the sputtered particles emitted from the wafer flew to the wafer 23 from various directions, they did not reach the bottoms of contact holes, via holes, etc., and the embedding characteristics (bottom coverage ratio) thereof deteriorated. .

As a measure against the above problem, Japanese Patent Laid-Open No. 1-116 has been proposed.
A collimating sputtering method as described in Japanese Patent Laid-Open No. 070 is known. This summary is as shown in FIG.
A collimator 30 having a large number of through holes 29 with a high aspect ratio is arranged in parallel between the target 21 and the wafer 23 to form a film.

According to this collimating sputtering method, sputtered particles 31 flying obliquely with respect to the wafer 23.
Are blocked by adhering in the many through holes 29 of the collimator 30. On the other hand, the sputtered particles 31 flying in a direction substantially perpendicular to the wafer 23 have a large number of through holes 2.
Pass through 9. As a result, only the sputtered particles 31 which are incident on the wafer 23 substantially perpendicularly are made into the wafer 2.
Since the film is attached to and deposited on the substrate 3, the burying property at the bottom of the contact hole, the via hole, etc. can be greatly improved.

[0009]

However, in the collimating sputtering method in which a thin film is formed using the collimator 30 having a large number of through holes 29 as described above, sputtered particles 31 flying obliquely are formed by the through holes 29. Due to the characteristic of blocking, a thin film of sputtered particles 31 is also formed on the sidewall of the through hole 29 during film formation on the wafer 23. Therefore, if the sputter film formation is performed for a long time, the thin film formed on the side wall of the through hole 29 is gradually thickened, and eventually cracks and peels off. Since the peeled thin film is much larger (order of magnitude) than the sputtered particles 31, it causes the generation of particles in the chamber 25 and adheres to the wafer 23 as a foreign substance, which significantly reduces the product yield. There was a problem.

Further, since the sputtered particles 31 adhere to the collimator 30 as described above, it has conventionally been necessary to periodically replace the collimator 30 with a new one or clean it. Generally, the replacement frequency of the collimator 30 is several times higher than the replacement frequency of the target 21, and since the replacement of the collimator 30 needs to be performed with the chamber 25 open to the atmosphere, the cost is significantly increased and the operating rate of the apparatus is high. There was also a problem that

Therefore, according to the present invention, when a thin film is formed by using a collimator having a large number of through holes, the thin film is not formed in the collimator and the generation of particles in the chamber can be prevented. An object is to provide a film forming method.

[0012]

In order to achieve the above object, the sputtering apparatus of the present invention comprises a collimator having a large number of through holes between a target electrode and a substrate electrode arranged in a chamber. In the provided sputtering apparatus, the material of the collimator is the same as the material of the target, and the collimator is configured to be capable of discharging in the large number of through holes. Another sputtering apparatus of the present invention is a sputtering apparatus including a collimator having a large number of through holes between a target electrode and a substrate electrode arranged in a chamber, wherein the plurality of through holes of the collimator are provided. Since it is configured to discharge in the hole,
The plurality of through-holes of the collimator are formed by arranging a plurality of bent metal plates so as to face each other, and an electric discharge is generated between two metal plates facing each other of the plurality of metal plates. There is something.

Further, in the sputter film forming method of the present invention, among the sputtered particles emitted from the target, the sputtered particles that obliquely fly to the substrate are blocked by the collimator having a large number of through holes, and the sputtered particles are projected onto the substrate. On the other hand, in a sputtering film forming method for selectively passing only sputtered particles flying in a substantially vertical direction to form a thin film on the substrate, the material of the collimator is the same as that of the target, and the collimator is the same. The electric discharge is generated in the large number of through holes, and the sputtered particles that are blocked by the large number of the through holes and adhere to the through holes are re-sputtered. Further, in another sputter film forming method of the present invention, among the sputtered particles emitted from the target, the sputtered particles that fly obliquely to the substrate are blocked by a collimator having a large number of through holes, and In the sputtering film forming method of selectively passing only sputtered particles flying in a substantially vertical direction to form a thin film on the substrate, a plurality of bent metal plates are arranged to face each other, and A plurality of through holes are formed, and the plurality of metal plates face each other 2
A discharge is generated between each of the metal plates, and the sputtered particles that are blocked by the large number of through holes and adhere to the through holes are re-sputtered.

[0014]

According to the present invention configured as described above, among the sputtered particles emitted from the target during plasma discharge in the chamber, sputtered particles flying obliquely to the substrate penetrate a large number of collimators. Blocked by holes. However, apart from the plasma discharge in the chamber,
Since plasma discharge occurs in many through holes of the collimator, even if sputtered particles, which are the source of thin film formation, adhere to the sidewalls of the through holes, the sputtered particles are generated in the through holes. It is resputtered by the ions in the plasma. Therefore, a thin film is not formed in many through holes of the collimator.

[0015]

Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic configuration diagram of a sputtering apparatus in the embodiment, FIGS. 2A and 2B are schematic plan views and side views of a collimator in the embodiment, and FIG. 3 is a through hole for explaining resputtering of the collimator in the embodiment. FIG. 4 is an enlarged sectional view of a hole portion, and FIG. 4 is a schematic plan view of a collimator in another embodiment.

First, as shown in FIG. 1, in this sputtering apparatus, an electrode 2 provided with a target 1 which is a thin film base material is installed.
And an electrode 4 on which a wafer 3, which is a substrate for forming a thin film, is installed, are arranged in a chamber 5 so as to face each other at a predetermined interval. Further, the chamber 5 includes a gas introduction pipe 6 and an exhaust pipe 7.
Also, a vacuum pump 9 is provided, and a predetermined DC voltage is applied between the electrode 2 and the electrode 4 by a DC power supply 8. Then, the collimator 10 has the electrode 2
And the electrode 4 are arranged in parallel.

Next, as shown in FIGS. 2A and 2B, the collimator 10 is formed by arranging a plurality of metal plates 11 so as to face each other. Each metal plate 11
Are alternately formed to be bent in opposite directions into a substantially half-hexagonal shape, and a large number of honeycomb-shaped through holes 12 are formed by facing a large number of these metal plates 11.
Is configured. In this embodiment, each metal plate 11
Is a stainless steel plate, and the space between the metal plates 11 is 10 mm for S ₁ which is the through hole 12 portion and 0.5 mm for S ₂ which is the adjacent portion. Further, as shown in FIG. 2B, the width T of each metal plate 11 is 15 mm. Note that S ₂ is 0.
If it is about 5 mm, the aspect ratio of this portion is very high, so that sputtered particles hardly adhere to the gap of this adjacent portion.

The plurality of metal plates 11 are supported by insulating plates 13a and 13b at both ends thereof,
Every other one end of the metal plate 11 is connected to the electrode 14a outside the one insulating plate 13a, and the other end of the metal plate 11 that is not connected to the electrode 14a is outside the insulating plate 13b. Is connected to the electrode 14b.

Then, as shown in FIG. 1, the electrode 14a and the electrode 1 of the collimator 10 arranged in the chamber 5 are arranged.
An AC power supply 15 is connected to the 4b.

With the above structure, the AC power supply 15 applies a potential difference between the electrodes 14a and 14b of the collimator 10, for example, by applying a positive potential and a negative potential, so that the metal plates 11 facing each other have positive and negative charges. Take on. Therefore, by applying an appropriate voltage between the electrodes 14a and 14b in a certain vacuum state, it is possible to cause discharge in each through hole 12 of each metal plate 11 facing each other.

In the sputtering apparatus constructed as described above, as shown in FIG.
After evacuating from the exhaust pipe 7 by means of, for example, Ar gas is introduced into the chamber 5 through the gas introducing pipe 6, and a predetermined power is applied between the electrode 2 and the electrode 4 by the DC power supply 8 to generate plasma. Let The target 1 is sputtered by Ar ⁺ ions in the plasma. At this time, the AC power supply 15 also applies a predetermined power to the collimator 10.

The sputtered particles emitted from the surface of the target 1 fly to the collimator 10 from various directions. Of these sputtered particles, particularly those flying in a direction substantially perpendicular to the wafer 3 reach the wafer 3 through a large number of through holes 12 of the collimator 10. Therefore, good burying characteristics can be obtained in forming a thin film on the bottom of a contact hole or a via hole.

By the way, during the sputtering film formation as described above,
Sputtered particles flying obliquely to the wafer 3 are
Although it is blocked by each through hole 12 of the collimator 10 and adheres to its side wall, a local plasma discharge occurs in each through hole 12 of the collimator 10 in addition to the plasma discharge in the chamber 5. For this reason, as shown in FIG.
Even if the sputtered particles 16 adhere to the metal plate 11 on the minus side, the sputtered particles 16 adhere to the metal plate 11 constituting the through hole 1
It is re-sputtered by Ar ⁺ ions 17 in the plasma generated in the No. ² plasma. Therefore, a thin film is not formed in each through hole 12 of the collimator 10, and the re-sputtered sputtered particles 16 are substantially the same as the sputtered particles from the target 1. Occurrence is prevented.

Incidentally, a large number of through holes 12 of the collimator 10 are provided.
When each through hole 12 is constituted by two metal plates 11 facing each other when a discharge is generated in one of the metal plates 11 facing each other, one of the potentials applied to every other metal plate 11 is positive and the other is the other. Is fixed to minus, Ar in the through hole 12
Only the sputtered particles 16 attached to the minus side metal plate 11 by the ⁺ ions 17 are re-sputtered. Therefore, an AC voltage is applied to each metal plate 11 by the AC power supply 15 to switch between positive and negative of each metal plate 11 to uniformly re-sputter the sputtered particles 16 attached to each metal plate 11.

Next, in the above-described sputtering apparatus and sputtering film forming method, the particles inside the chamber 5 were checked depending on whether or not a voltage was applied to the collimator 10.

As shown in FIG. 1, the target (Ti) 1
The collimator 10 is disposed between the wafer 3 and the wafer 3, and the chamber 5 is once evacuated to the order of 10 ⁻⁸ Torr, and then pure Ar gas is introduced to set the degree of vacuum to about 5 mTorr. Approximately 13K between electrodes 2 and 4 by DC power supply 8
W power was applied. The sputtering time was a condition for forming a Ti thin film of 1 μm on the wafer 3. The collimator 10
When applying a voltage to the
W power was applied.

Under the above sputtering conditions, the wafer 5000
The film deposition process was performed on the sheets, and the particle check in the chamber 5 was performed every time the film deposition process was completed. Here, Table 1 shows a comparison of the number of particles generated in the chamber 5 having a size of 0.3 μm or more when the voltage is not applied to the collimator 10 and when the voltage is applied.

[0028]

[Table 1]

As is clear from the results shown in Table 1, when the voltage is applied to the collimator 10, the number of particles generated in the chamber 5 is small, and the number of particles is greatly increased even when the processing of 5000 wafers is performed. Was not seen.

After the film deposition process for 5000 wafers 3 is completed, the chamber 5 is opened to the atmosphere and the collimator 10 is observed. When no voltage is applied, the sputtered film is adhered and many cracks are observed on the film surface. Was given. On the other hand, when a voltage was applied to the collimator 10, no sputtered film was attached to the collimator 10.

If the voltage applied to the collimator 10 is too high, the sputtered particles that should normally pass through the through holes 12 may be disturbed, and further, the film adhered to the metal plate 11 may be re-sputtered. There is a risk of sputtering the material itself of the metal plate 11. Therefore, the discharge voltage in the through hole 12 of the collimator 10 needs to be set in consideration of the size of the through hole 12 as well as the plasma discharge and the pressure in the chamber 5.

Further, in the above-mentioned embodiment, the collimator 1
Although the material of No. 0 was stainless steel and Ti was used as the target 1, if the material of the collimator 10 is the same as the material of the target 1, even if the collimator 10 itself is sputtered as described above, it is formed on the wafer 3. It is possible to prevent contamination of the sputtered film to be formed.

Regarding the structure of the collimator 10 shown in FIG. 2, for example, as shown in FIG. 4, a plurality of through holes 12 are formed by arranging a plurality of metal plates 11 bent and formed in a wave shape so as to face each other. You may. In addition, various effective structures capable of discharging in a plurality of through holes can be used.

The embodiments of the present invention have been described above.
The present invention is not limited to the above embodiments, and various effective modifications and applications are possible based on the technical idea of the present invention. In addition, although the two-electrode discharge type sputtering apparatus has been described in the embodiment, various methods can be adopted as a basic configuration of the sputtering apparatus.

[0035]

As described above, according to the present invention,
It is possible to effectively prevent the generation of particles in the chamber by preventing the sputtered film from being formed on the collimator during sputter film formation by causing an electric discharge in the many through holes of the collimator. The yield can be significantly improved. In particular, by making the material of the collimator the same as the material of the target, it is possible to prevent contamination of the sputtered film formed on the wafer even if the applied voltage is too high and the collimator itself is sputtered. .

Further, since it is not necessary to regularly replace or clean the collimator, it is possible to significantly reduce the cost, and it is possible to reduce the number of times the chamber is opened to the atmosphere and significantly improve the operating rate. .

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a sputtering apparatus according to an embodiment of the present invention.

FIG. 2 shows the collimator in the above embodiment, (a)
Is a schematic plan view, and (b) is a schematic side view.

FIG. 3 is an enlarged cross-sectional view of a through hole portion for explaining resputtering of the collimator in the above embodiment.

FIG. 4 is a schematic plan view of a collimator according to another embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of a conventional sputtering apparatus.

FIG. 6 is a configuration diagram illustrating an operation of a collimator in a conventional sputtering device.

[Explanation of symbols]

1 Target 2 Electrode 3 Wafer 4 Electrode 5 Chamber 6 Gas Inlet Pipe 7 Exhaust Pipe 8 DC Power Supply 9 Vacuum Pump 10 Collimator 11 Metal Plate 12 Through Holes 13a, 13b Insulating Plates 14a, 14b Electrode 15 AC Power Supply 16 Sputtered Particles 17 Ar ⁺ Ions

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 21/203, 21/363 C23C 14/00-14/56

Claims (6)

(57) [Claims] 1. A sputtering apparatus comprising a collimator having a large number of through holes between a target electrode and a substrate electrode arranged in a chamber, wherein the collimator is made of the same material as the target. At the same time, the sputtering device is configured to be capable of discharging in the large number of through holes of the collimator. 2. A sputtering apparatus including a collimator having a large number of through holes between a target electrode and a substrate electrode arranged in a chamber, wherein discharge is possible in the large number of through holes of the collimator. Therefore, the plurality of through holes of the collimator are formed by arranging a plurality of bent metal plates so as to face each other, and discharge is performed between two metal plates facing each other of the plurality of metal plates. Sputtering device characterized by causing. 3. The sputtering apparatus according to claim 2, wherein an AC voltage is applied between two metal plates of the plurality of metal plates facing each other. 4. A power supply unit for applying a voltage to the collimator, wherein discharge is caused in the plurality of through holes to remove the film attached to the collimator. 4. The sputtering apparatus according to any one of 3 to 3. 5. A sputter particle, which is sputter particles emitted from a target, is shielded by a collimator having a large number of through-holes, and spatter particles that fly obliquely with respect to the substrate, and fly substantially perpendicular to the substrate. In a sputtering film forming method of selectively passing only particles to form a thin film on the substrate, the material of the collimator is the same as the material of the target, and the collimator has a plurality of through holes. A sputtering film forming method characterized in that a discharge is generated, and the sputtered particles that are blocked by the large number of through holes and adhere to the through holes are re-sputtered. 6. A sputter particle emitted from a target, which is shielded by a collimator having a large number of through-holes and which spatters obliquely to the substrate, and which is substantially perpendicular to the substrate. In the sputtering film forming method of selectively passing only particles to form a thin film on the substrate, the plurality of through holes of the collimator are formed by arranging a plurality of bent metal plates so as to face each other, Discharge is generated between two metal plates facing each other of the plurality of metal plates, and the sputtered particles blocked by the plurality of through holes and adhering to the through holes are re-sputtered. Deposition method.