JP3080945B1 - High efficiency plasma gas condensing cluster deposition system - Google Patents

Abstract

To generate clusters of uniform size in a glow discharge region under a high rare gas partial pressure, and to enable the clusters to fly to a substrate 32 stably. It prevents abnormal discharge, accumulation of clusters around the target 20, and the like. SOLUTION: A target 20 and a substrate 32 are arranged in a separate sputtering chamber 22 and a film forming chamber 35, respectively, and a gas pressure of the former is a glow discharge region of about several Torr, and the latter is maintained at a sufficiently high vacuum. . Further, the shield cover 2 surrounding the target 20 is provided, and the gap δ between the shield cover 34 and the target 20 is sufficiently narrowed to suppress abnormal discharge under glow discharge. Clusters are prevented from being deposited on the surface of the target 2 or the target 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method of combining metal vapor generated from a target by a sputtering method.
An apparatus for condensing to form clusters and depositing them on a substrate. In particular, by performing sputtering in a glow discharge region with a relatively high Ar gas pressure of several Torr,
The present invention relates to a high-efficiency plasma gas condensed cluster deposition apparatus suitable for generating clusters having a diameter of about several nm and depositing the clusters on a substrate to form a film.

[0002]

2. Description of the Related Art As a means for forming a metal or semiconductor thin film, a sputtering method is used. In this sputtering method, a high voltage is applied between a cathode and an anode which are arranged to face each other in a vacuum chamber, and the inside of the vacuum chamber is maintained in a glow discharge region of about 10 ^-2 to 10 ^-3 Torr, Atoms and molecules generated by sputtering a target held on a cathode are deposited on a substrate.

The sputtering method has an advantage that an element or a compound having a high melting point and a low vapor pressure can be formed into a film. However, the conventional sputtering method performed in the glow discharge region has a disadvantage that the size and dispersion state of the cluster cannot be controlled because the coalescence and condensation of metal atoms occur on the substrate to form a cluster. Therefore, by sputtering in a glow discharge region having a relatively high gas pressure of about several Torr, atoms and molecules generated from the target are aggregated under a relatively high gas pressure, thereby forming a cluster having a relatively large particle size. A method has been proposed in which the light is generated and deposited on a substrate.

[0004]

However, when sputtering is performed at a relatively high gas pressure, the generated cluster collides with a rare gas molecule before flying to the substrate, secondary growth of the cluster occurs, and the size distribution is reduced. Not only becomes remarkable, but also it becomes difficult to perform efficient deposition in a clean atmosphere. Further, since these clusters are deposited on the wall around the target in the sputtering chamber, the apparatus cannot be operated for a long time. In addition, abnormal discharge easily occurs, and stable discharge is not easily performed.

In view of the problems to be overcome in the high-efficiency plasma cluster condensing cluster deposition apparatus of the sputtering type, the present invention has achieved uniform size by sputtering in a glow discharge region having a relatively high gas pressure of about several Torr. In addition to generating clusters, it enables the clusters to fly stably onto the substrate, thereby increasing the generation efficiency and preventing abnormal discharge, accumulation of clusters around the target, etc., and enabling stable film formation. With the goal.

[0006]

In order to achieve the above-mentioned object, according to the present invention, the target 20 and the substrate 32 are disposed in separate sputtering chambers 22 and film forming chambers 35, respectively, and the gas pressure of the former is reduced by several. A glow discharge region of the order of Torr is used,
Maintain a high vacuum of the order of 0 ^-7 Torr. Further, the shield cover 2 surrounding the target 20 is provided, and the gap δ between the shield cover 2 and the target 20 is sufficiently narrowed to suppress abnormal discharge such as glow discharge. Clusters were prevented from being deposited on the surface of the target 20.

That is, in the cluster deposition apparatus according to the present invention, the rare gas Ar is introduced into the vacuum chamber 1 for confining the discharge region, and the negative voltage cathode 18 in the sputtering chamber 22 and the target 20 mounted thereon are provided. Glow discharge is generated between the cooling case 3 and the zero voltage cooling case, and metal atoms generated by sputtering the target 20 with positive rare gas atom ions collide with a rare gas such as Ar or He, and are cooled. Form clusters.

In this high efficiency plasma gas condensing cluster deposition apparatus, the sputtering chamber 22 on the side of the target 20 is maintained in a glow discharge region in a rare gas at a relatively high pressure. The metal atoms are cooled by the collision with the rare gas, are coalesced and condensed, and a cluster having a uniform size with a diameter of about several nm can be constantly generated. On the other hand, since the film formation chamber 35 in which the substrate 32 is installed is maintained at a sufficiently high degree of vacuum, clusters can be deposited in a clean atmosphere.

More specifically, nozzles 26 to 29 are provided between the sputtering chamber 22 on the target 20 side and the film forming chamber 35 on the substrate 32 on a path where molecules emitted from the target 20 enter the substrate 32. Rooms 23, 24, and 25 are provided which are partitioned by a plurality of arranged partitions. Then, by changing the gas pressure in a stepwise manner, the sputtering chamber 22 on the target 20 side is maintained in a glow discharge region, and the film forming chamber 35 on the substrate 32 side is set to a sufficiently higher vacuum degree.

In this high-efficiency plasma-gas-condensed cluster deposition apparatus, a plurality of chambers 23, 24,
Since the degree of vacuum of 25 was changed stepwise, target 2
The sputter chamber 22 on the 0 side and the film forming chamber 35 on the substrate 32 side can be stably maintained at required gas pressures.
In addition, since the nozzles 26 to 29 are arranged on the partition walls defining the rooms 23, 24, and 25 on the path where the molecules emitted from the target 20 enter the substrate 32, the target 2
The cluster can reliably fly from 0 to the substrate 32.

The target 20 is disposed so as to be movable back and forth with respect to a partition partitioning the nozzle 26 and the adjacent room 23. Thereby, in the sputtering chamber 22, it is possible to change the distance in which the metal atoms protruding from the target 20 pass through the relatively high rare gas pressure.
Thereby, the number of collisions between metal atoms or clusters and rare gas atoms can be adjusted, the cluster growth region can be changed, and the size of generated clusters can be changed.

The shield cover 2 is disposed around the target 20 except for a path where the molecules that have jumped out of the target 20 are emitted in a beam toward the substrate 32. The shield cover 2 is disposed between the shield cover 2 and the sputtering surface of the target 20. Is set to about 0.3 mm. Thereby, occurrence of abnormal discharge such as glow discharge is suppressed, and stable discharge is enabled.

Further, the shield cover 2 and the target 2
By flowing a rare gas into the gap δ between the target and the 0 sputtering surface, the wall surface around the target 20 is always kept clean, and clusters are prevented from being deposited on the wall surface. Thereby, glow discharge can be maintained for a long time.

[0014]

Embodiments of the present invention will now be described specifically and in detail with reference to the drawings.
FIG. 1 shows an overall outline of a high-efficiency plasma gas condensed cluster deposition apparatus according to the present invention, and FIG.

A cylindrical cooling case 3 is housed and fixed in the center of the vacuum chamber 1. The inside of the cooling case 3 is a sputtering chamber 22. A cooling pipe 4 wound around the outer periphery of the cooling case 3
A coolant such as liquid nitrogen circulates through the chamber to cool the inside of the sputtering chamber 22.

The sputtering chamber 22 is evacuated by the turbo molecular pump 5 and is shut off from the pump 5 after reaching a vacuum of the order of 10 ^-8 Torr. After that, the He gas whose flow rate is controlled by the mass flow controller 15 through the rare gas introducing pipe 14 and the Ar gas whose flow rate is controlled by the mass flow controller 12 through the rare gas introducing pipe 11 are introduced into the sputtering chamber 22.
Gas or the like is introduced. On the other hand, since the adjacent room 23 is evacuated by the high-efficiency mechanical booster pump, the sputter chamber 22 is also evacuated through the nozzle 26.
The pressure in the sputtering chamber 22 is measured by the vacuum gauge 16 and the measurement result is transmitted to the mass flow controllers 12 and 1.
5 is fed back. In this way, the sputtering chamber 22 is maintained at a rare gas partial pressure of about 1-10 Torr.

On the central axis of the cooling case 3,
1 and 2, a nozzle 26 is opened at the right end face, and communicates with the chamber 23 adjacent to the sputtering chamber 22 via the nozzle 26. This room is evacuated by a mechanical booster pump 6. At the center of the sputtering chamber 22, a cathode 18 for holding a target 20 for generating clusters is arranged. The cathode 18 is provided at one end of a cylindrical transfer rod 21 and is installed toward the nozzle 26.

The transfer rod 21 is arranged on the central axis of the vacuum chamber 1 and the cooling case 3, and the other end is hermetically sealed by a sealing guide 10 provided on the left end face of the vacuum chamber 1 in FIG. It is slidably supported in the upright position. The transfer rod 21 is connected to the sealing guide 10.
1 can slide in the longitudinal direction, as indicated by the arrow in FIG. 1, so that the position of the cathode 18 can be adjusted in the same direction.

A plurality of magnets 34 are arranged concentrically inside the cathode 18, whereby a magnetic field is formed on the cathode 18. Electrons generated by the target serving as a cathode receive Lorentz force due to the magnetic field and perform magnetron motion. Therefore, ionization of Ar gas by the electrons is promoted, and the amount of metal atoms generated by sputtering increases. The transfer rod 21 is provided inside the cathode 18.
Cooling water is circulated through a cooling pipe 13 passing through the inside of the target to be cooled, thereby preventing the target from being heated and melted.
On the front surface of the cathode 18, a target 20 for sputtering by bombarding ions on the surface is held.

The periphery of the cathode 18 and the target 20 on the front surface thereof are covered with a cylindrical shield cover 2, and the front surface of the shield cover 2 projects toward the center of the target 20, and the inner peripheral edge thereof is formed by the cathode 18. And the outer peripheral side of the target 20. As a result, the cathode 18 and the target electrode 20 are covered with the shield cover 2 except for a path through which atoms and molecules ejected from the target electrode 20 are emitted toward the substrate 32 described later.

As shown in FIG. 2, this shield cover 2
Is formed between the front portion of the target 20 and the target 20, and the gap δ is set to about 0.3 mm. The shield cover 2 and its surrounding members are preferably coated with a high-voltage resistant insulating film such as a fluororesin, for example, a trade name of “Teflon”.

As shown in FIGS. 1 and 2, a pipe 11 for introducing a rare gas is disposed inside the transfer rod 21, and the pipe 11 is connected to an inner peripheral portion of the shield cover 2. Further, an inner peripheral portion of the shield cover 2 communicates with a distance δ between a front portion of the shield cover 2 and the target 20. When Ar gas is introduced as a rare gas from the pipe 11 while controlling the flow rate by the mass flow controller 12, the Ar gas passes through the inside of the shield cover 2 and is measured from the distance δ between the front surface of the shield cover 2 and the target 20. It flows into the sputtering chamber 22.

A film forming chamber 35 is formed at an end of the vacuum chamber 1 opposite to the side where the sealing guide 10 of the transfer rod 21 is provided. This film forming chamber 3
5, a holder 31 is arranged.
1 holds the substrate 32. The holder 31 can be moved in the radial direction of the film forming chamber 35 by the transfer rod 30. When the substrate 32 is arranged at the center of the film forming chamber 35 as shown in FIG. The target 20 faces.

A film thickness meter 33 is disposed behind the holder 31 to monitor the weight of the clusters deposited on the substrate 32. A vacuum pump 9 such as a turbo molecular pump is connected to the film forming chamber 35, and 10 ⁻⁷ Torr is maintained even during cluster deposition.
It is maintained at a high degree of vacuum of about r.

The partition between the sputtering chamber 22 on the target 20 side and the film forming chamber 35 on the substrate 32 is divided into a plurality of chambers 23, 24, 25. A nozzle 26 on a straight path connecting the target 20 and the substrate 32,
27, 28, and 29 are arranged, and a plurality of adjacent chambers 23, 24, and 25 including the sputtering chamber 22 and the film forming chamber 35 are provided.
Communicates only through these nozzles 26, 27, 28, 29. The target 20 and the substrate 32 face each other through the nozzles 26, 27, 28, and 29.

As described above, the sputtering chamber 22 is
Rare gases such as Ar and He are introduced through 1 and 14, and the chamber 23 is evacuated by a mechanical booster pump.
The degree of vacuum is maintained at about 0 Torr. The film forming chamber 35 is connected to a vacuum pump 9 such as a turbo molecular pump, and is maintained at a vacuum degree of the order of 10 ⁻⁷ Torr. The chamber 2 from the sputtering chamber 22 to the film forming chamber 35
A mechanical booster pump 6 and turbo molecular pumps 7 and 8 are connected to 3, 24 and 25, respectively, and are maintained at a vacuum degree of 10 ⁻² Torr, 10 ⁻⁴ Torr and 10 ⁻⁶ Torr, respectively. That is, the degree of vacuum in the chambers 23, 24, and 25 is maintained so as to gradually increase (the gas pressure decreases) as the distance from the sputtering chamber 22 to the deposition chamber 35 increases. A vacuum gauge 17 is attached to the room 23, and the degree of vacuum at that portion is measured.

The target 20 made of metal is sputtered by using the high-efficiency plasma-gas-condensed cluster deposition apparatus having the above-mentioned structure, and the generated target atoms and molecules are combined and condensed to form a cluster. Is deposited on the surface. Next, the procedure will be described.

As described above, the mass flow controller 1
The He gas is introduced into the sputtering chamber 22 through the pipe 14 while controlling the flow rate by 5. While controlling the flow rate by the mass flow controller 12, Ar gas is introduced from the pipe 11, and the Ar gas is supplied to the sputtering chamber 2 from the distance δ between the front surface of the shield cover 2 and the target 20.
Pour into 2

On the other hand, the gaseous atoms and clusters in the sputtering chamber 22 are connected to the exhaust port of the chamber 23 through the nozzle 26 and are discharged by the mechanical booster pump 6. Thereby, the sputtering chamber 22 is set to 1 to 10 Torr.
Maintain a gas pressure of about r. On the other hand, the film forming chamber 35 is evacuated by the vacuum pump 9 to maintain a high degree of vacuum of about 10 ⁻⁷ Torr. The intermediate of the room 23, 24, 25 extending from these sputtering chamber 22 into the deposition chamber 35, respectively evacuated by a vacuum pump 6, 7, 8, respectively ^10-2
Torr, 10 ^-4 Torr, 10 ^-6 Torr, and a high degree of vacuum (low gas pressure) is maintained stepwise.

In this state, the cooling case 3 is grounded (0 potential) and a high negative voltage is applied to the cathode 18. Also,
The shield cover 2 is also grounded. In a normal arrangement, an arc discharge occurs between the front portion of the shield cover 2 and the target 20. Therefore, the gap δ between the front portion of the shield cover 2 and the target 20 is set to an interval of about 0.3 mm, so that abnormal discharge hardly occurs and glow discharge is stably maintained.

This glow discharge and the magnet 3 inside the cathode 18
By the magnetic field of No. 4, rare gas atoms near the surface of the target 20 are excited and ionized. The positive ions of Ar are accelerated by the negative high voltage applied to the cathode 18 and collide with the surface of the target 20 to sputter the target 20. By this sputtering, the target 20
Atoms and molecules fly out of

The metal atoms and molecules jumping out of the target 20 collide with the rare gas atoms while passing through the sputter chamber 22 in a rare gas atmosphere having a relatively high pressure of 1 to 10 Torr, and are cooled and united and condensed. Grow as large clusters of uniform size. Here, when the transfer rod 21 is moved along the sealing guide 10 in the direction shown by the arrow in FIG. 1 and the target 20 is moved, the distance L between the target 20 and the nozzle 26 shown in FIG. 2 can be changed. Since the number of collisions between the metal atoms and molecules and the rare gas atoms that have jumped out of the target 20 depends on L and the distance of the cluster growth region can be changed, a cluster having an arbitrary uniform size can be formed on the film forming chamber 35 side. Can be taken out.

The clusters generated in the target chamber 22 pass through the nozzles 26, 27, 28 and 29, and pass through the chambers 23, 24 and 25 where the degree of vacuum is gradually increased.
Deposition chamber 3 maintained at a high degree of vacuum of about 10 ^-7 Torr
5 and reaches the surface of the substrate 32 on the holder 31 and is deposited there. The weight of the cluster deposited on the substrate 32 is measured by a separately calibrated film pressure gauge 33.

In this high-efficiency plasma gas condensing cluster deposition apparatus, the sputtering chamber 2 with a relatively high Ar gas partial pressure is used.
The cluster generated in step 2 is made to fly toward the film formation chamber 35 maintained at a high vacuum degree, where it can be deposited on the substrate 32. Since the degree of vacuum in the plurality of chambers 23, 24, and 25 between the sputtering chamber 22 and the film forming chamber 35 is changed stepwise, the sputtering chamber 22 on the target 20 side and the film forming chamber 35 on the substrate 32 side are changed. Can be stably maintained at required gas pressures.

By setting the gap δ between the shield cover 2 and the sputtering surface of the target 20 at about 0.3 mm, the occurrence of abnormal discharge in the glow discharge region can be suppressed, and stable discharge can be achieved. . Further, the gap δ between the shield cover 2 and the sputtering surface of the target 20 is
By flowing a rare gas such as r, clusters can be prevented from being deposited on the surfaces of the shield cover 2 and the target 20.

In the above description of the embodiment, the case where a metal is used as the target 20 has been described. However, by taking measures such as applying a high frequency power between the cathode 18 and the holder 31, the semiconductor or the semiconductor can be used. These clusters can also be generated and deposited on the substrate 32 using an insulator target 20.

[0037]

As described above, according to the present invention, by performing sputtering in a glow discharge region having a relatively high gas pressure of about several Torr, clusters having a uniform size can be efficiently generated, and abnormal discharge, This prevents clusters from being deposited around the target and enables the clusters to fly stably onto the substrate, thereby enabling stable cluster deposition. Accordingly, deposition can be performed even at a high film forming rate of about 1.0 nm / sec.

[Brief description of the drawings]

FIG. 1 is a schematic vertical sectional side view showing an outline of a high-efficiency plasma gas condensed cluster deposition apparatus according to the present invention.

FIG. 2 is a schematic enlarged vertical sectional side view showing a main part of the high-efficiency plasma gas condensed cluster deposition apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum chamber 2 Shield cover 18 Cathode 20 Target 22 Sputter chamber 23 Room 24 Room 25 Room 26 Nozzle 27 Nozzle 28 Nozzle 29 Nozzle 31 Holder 32 Substrate 35 Film formation chamber δ Distance between shield cover and target

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tateyuu Saito 4946-3 Nakane, Hitachinaka-shi, Ibaraki Prefecture (72) Inventor Tomoyuki Nimura 5011 Yamato Koibuchi Uchihara-cho, Higashiibaraki-gun, Ibaraki Pref. 280139 (JP, A) Tokuhyo Hei 3-503425 (JP, A) ISSPIC 9 "NINTH IN TERNATIONAL SYMPOS IUM ON SMALL PARTICLES AND INORGANIC CLUSTERS SECON sci- ent sci- ent sci- ent sci- ents" (1998) Crypto sci- sion (1998) "plasma-gas-condensation method" (58) Fields investigated (Int. Cl. ⁷ , DB name) C23C 14/00-14/58 B22F 9/02 JICST file (JOIS)

Claims (4)

(57) [Claims] 1. A rare gas is introduced into a vacuum chamber (1) capable of maintaining a high vacuum state while maintaining a high gas partial pressure, and a cathode (18) is connected to a grounded cooling case (3). A negative voltage is applied to a target (20) placed thereon to generate a glow discharge in a sputtering chamber (22), and neutral or ionized atoms generated by sputtering of the target (20) with rare gas ions are converted into a rare gas. The target (20) has a cluster source capable of colliding with and cooling to form a cluster.
2) moving the target (20)
Formation region due to condensation of atoms sputtered from
The staying time of the cluster and control the size of the generated cluster
And a high efficiency plasma gas condenser cluster deposition apparatus characterized by depositing the generated clusters on a substrate (32). 2. A sputtering chamber (22) in which a target (20) is arranged and a film forming chamber (3) in which a substrate (32) is arranged.
5) was evacuated, the cluster generated in the sputtering chamber (22) was taken out to the room (23) through the nozzle (26), and the growth of the cluster was terminated. Later, the nozzles (27), (28), (2
9) is placed and passed through a plurality of chambers (24) and (25) in which the degree of vacuum is changed stepwise, and on a substrate (32) installed in a film forming chamber (35) in a high vacuum and clean atmosphere. 2. The apparatus according to claim 1, wherein clusters are deposited on the clusters. 3. A shield cover (2) is arranged around the target (20) while leaving a path for firing from the target (20) toward the substrate (32), and the shield cover (2) and the target (20) are disposed. 3. ) The apparatus according to claim 1, wherein the gap (.delta.) Between the sputtering surface and the sputtering surface is set to about 0.3 mm to prevent arc discharge. 4. A shield (2) and a target (2).
0) a rare gas is passed through the gap (δ) between the sputtering surface and
The high-efficiency plasma gas condensed cluster deposition apparatus according to claim 3 , wherein an electrical short due to adhesion of metal vapor or clusters is suppressed.