JPH07122135B2 - Ion-assisted sputtering method and apparatus - Google Patents

Description

The present invention relates to an ion assisted sputtering method and apparatus, and more particularly to a film-shaped or plate-shaped substrate or a substrate inserted in a plate-shaped tray as a target. An ion-assisted sputtering method in which the passing type sputtering device for film formation while having a relative movement has the ion assist function, and the structure and quality of the thin film can be arbitrarily controlled to suit the purpose of use. And its device.

[Conventional technology]

Conventionally, when a thin film is efficiently formed on a substrate surface on a base in which a plurality of substrates are arranged side by side on a film or plate wound in a roll or on one tray, a rectangular cathode and a rectangular type are formed in a vacuum container. There is a passing type sputtering method in which a target is fixedly arranged, and the substrate material is opposed to the rectangular target in a direction perpendicular to the longitudinal direction of the rectangular target while moving at a constant speed. Further, in order to improve the film formation speed, a magnet group for forming a tunnel magnetic field is arranged on the back surface of the rectangular target, and the tunnel magnetic field traps plasma.
A high-density long track-shaped plasma ring can be formed. Further, the magnetic poles on the back surface of the rectangular target are composed of a substantially rectangular central magnetic pole and a long track-shaped outer peripheral magnetic pole arranged concentrically with the central magnetic pole on the outer periphery thereof, so that the polarities of the respective magnetic poles are opposite to each other. It is arranged. Also,
Generally, the central magnetic pole is a permanent magnet, the outer magnetic pole is a soft magnetic material, and the magnetic poles are magnetically coupled by a soft magnetic material yoke. Therefore, the central magnetic pole and the outer magnetic pole are magnetically balanced so that the outer magnetic pole tip portion and the central magnetic pole tip portion have the same magnetic flux to form a tunnel-like leakage magnetic field. Hereinafter, this state will be referred to as a complete magnetron, and such an electrode (cathode) will be referred to as a magnetron cathode.

The conventional design concept is aimed at a perfect magnetron, and the plasma is very well confined in this tunnel magnetic field, becomes a high-density plasma on the surface of the rectangular target, and realizes a high deposition rate.

[Problems to be Solved by the Invention]

However, according to such a sputtering method, the plasma density is low in the vicinity of the substrate and the ion density is low even when a bias voltage is applied to the substrate, so it is attempted to hit the substrate with ions to improve the film density and adhesion. I cannot expect the ion assist effect. Therefore, the central magnetic pole and the outer magnetic pole that form the magnetic pole body on the back surface of the rectangular target are unbalanced to weaken the plasma confinement and expand the plasma to the vicinity of the substrate.
A method is conceivable in which a self-bias voltage of the substrate itself or a bias voltage is positively applied to the substrate to accelerate and bombard the ions with the substrate. In addition, when the main discharge is a high frequency (RF) discharge, the plasma expansion becomes larger than that of a direct current (DC) discharge, and a slight improvement can be seen. However, each of the above-mentioned methods has a problem that the substrate has a limit of the ion density and the ion density distribution on the substrate is not uniform.

That is, the amount of ions reaching the substrate is J ₊ , the number of particles deposited on the substrate by sputtering from the target is J _m, and the number of ions reaching each second per unit area (1 cm ² ) of the substrate is j ₊ , and the ion flux ( Ion flux), and the unit area (1c
The number of spatter particles that reach every second per m ² ) is called j _m and is called a spatter particle flux. In addition, the ratio j ₊ / j _m between the ion flux j ₊ and the spatter particle flux j _m is calculated by the ion flux ratio (ion
flux ratio). The energy for accelerating and bombarding these ions on the substrate is E. Further, the combination of the ion flux ratio j ₊ / j _m and the acceleration energy (bias voltage) E to bombard the substrate with ions will be referred to as ion assist.

When various combinations of the ion flux ratio j ₊ / j _m and the acceleration energy (bias voltage) E are used for film formation, various properties of the film such as electric resistance, hardness, surface reflectance, magnetic properties, and optical properties can be controlled. can do. Further, when used in combination with the working gas pressure in the vacuum container, the deformation of the film and the substrate, that is, the internal stress can be adjusted.

However, the success or failure of these is determined by the ion flux ratio j ₊ / j _m
And the extent to which the acceleration energy E is in the adjustment range. Since the acceleration energy E can be solved by the specification of the bias power supply, it is a problem to make the ion flux ratio j ₊ / j _m large.

The increase or decrease in the amount of ions near the substrate is determined by the degree of magnetic balance between the central magnetic pole and the outer magnetic pole of the magnetic pole body on the back surface of the target. As the outer magnetic pole is strengthened with respect to the central magnetic pole, the plasma confining force between the central magnetic pole and the outer magnetic pole becomes weaker, the plasma expands to the vicinity of the substrate, and the ion density near the substrate increases. When the magnetic pole body is a permanent magnet, the saturation flux of the outer magnetic pole may be set larger than that of the central magnetic pole.
However, in this case, the increase / decrease of the ion density cannot be controlled, and has a constant value according to the discharge current. Therefore, if it is desired to increase or decrease the amount of ions, the magnetic pole body on the back surface of the target may be provided with a solenoid coil near the outer circumference of the outer circumference magnetic pole. The magnetic balance can be adjusted by the magnitude of the exciting current and the exciting direction of the solenoid coil. Further, since the number of the sputter particles and the number of ions increase / decrease almost in proportion to the discharge current, the ratio, that is, the ion flux ratio j ₊ / j _m itself hardly changes even if the discharge current is increased or decreased. Further, the exciting current of the solenoid coil for adjusting the magnetic balance of the magnetic pole body on the substrate surface side is limited to the range in which the track-shaped plasma ring contributing to the sputtering is formed, so that the ion flux ratio j ₊ / j _m 0.3 to 0.5
Is the upper limit.

[Means for Solving the Problems]

In order to solve such a problem, an ion assisted sputtering method according to the present invention is arranged such that a magnetic pole body is arranged on the back surface of a target to form plasma, and the magnetic body is formed on the back surface side of the substrate facing the magnetic pole body through the substrate. Is placed to guide and focus the plasma formed on the target surface to the substrate side, and a shutter that opens and closes in the same direction as the moving direction of the substrate is provided between the substrate and the target, and the opening and closing of this shutter is controlled from the target. The ratio of the ion flux reaching the substrate and the sputtered particle flux is adjusted.

The ion assisted sputtering device according to the present invention generates plasma formed by a magnetic pole body disposed on the back surface of a target and plasma formed on the target surface on the back surface side of the substrate which faces the target back pole body through the substrate. A plasma focusing means by a magnet body that focuses and guides to the substrate side, and a shutter whose opening is set in the same direction as the substrate moving direction are arranged between the substrate and the target, and the opening and closing of the shutter is controlled to control the ion flux. And a sputter particle flux adjusting means for adjusting the ratio between the sputter particle flux and the sputter particle flux.

[Action]

In the present invention, for example, in the direction in which the magnetic pole of the magnetic pole body on the back surface of the target is strengthened, the diffused plasma near the substrate is focused and becomes a high density. Also, by setting the opening of the shutter that is opened and closed in the same direction as the moving direction of the substrate between the substrate and the target to be approximately the same as the inner dimension of the ion focusing magnet body, it is possible to pass through the opening of the shutter. And high density of ions reach the substrate. The smaller the opening of the shutter and the inner dimension of the ion focusing magnet body, the larger the ion flux j _t and the smaller the spatter particle flux j _m become. Therefore, the ion flux ratio j ₊ / j _m can be increased. . When the shutter opening is made smaller, the spatter particle flux j _m becomes, and the ion flux ratio j ₊ / j _m becomes larger, but the film forming rate becomes smaller accordingly, so the opening can be adjusted appropriately according to the desired thin film. And the size of the focusing magnet body may be determined.

〔Example〕

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an overall configuration diagram of an ion assisted sputtering device for explaining an embodiment of the ion assisted sputtering method according to the present invention. In the figure, 1 is a valve 1a
A vacuum container having a substrate 2 that moves in the direction of arrow A, 3
Is a magnetic pole body as a plasma forming means, which is arranged to face the front surface side of the substrate 2, 4 is arranged between the substrate 2 and the magnetic pole body 3, and is in the same direction (arrow A direction) as the moving direction of the substrate 2 (arrow A direction).
A shutter which can be opened and closed in the (-B 'direction), 5 is an ion focusing magnet body as a plasma focusing means which is arranged to face the back side of the substrate 2, 6 is a heater for heating the inside of the vacuum container 1, and 7 is a magnet body 5. Is a power source for exciting the magnetic pole body 3, 9 is a power source for discharging the magnetic pole body 3, and 10 is a power source for applying a bias voltage to the thin film of the substrate 2.

FIGS. 2A to 2D are views for explaining the configuration of the peripheral portion of the plasma forming magnetic pole body 3 and the ion focusing magnet body 5 arranged on the front and back surfaces of the substrate 2 of FIG. The same figure (a)
In the reference numeral 31, 31 is a central magnetic pole made of a permanent magnet, 32 is an outer magnetic pole made of a permanent magnet, 33 is a yoke made of a soft magnetic material that magnetically couples the outer magnetic pole 32 of the central magnetic pole 31, 34 is a plasma generating electrode, Reference numeral 35 is a target, 36 is a solenoid coil arranged near the outer circumference of the outer magnetic pole 32 for adjusting the magnetic balance with the central magnetic pole 31, and 51 is an ion focusing solenoid coil arranged opposite to the back surface of the substrate 2. The ion focusing solenoid coil 51, the magnetic balance adjusting solenoid coil 36, the plasma generating electrode 34, and the substrate 2 are connected to predetermined power sources 7, 8, 9, and 10, respectively, as shown in FIG. The magnetic pole body 3 has a rod-shaped central magnetic pole 31 arranged in the central portion as shown in FIG. 2B, and a long track-shaped outer magnetic pole 32 and a magnetic balance adjusting solenoid coil 36 are provided in a predetermined space on the outer peripheral portion thereof. And is arranged. Further, in the magnet body 5, as shown in FIG. 3C, the ion-collecting solenoid coil 51 has a long track-shaped outer shape, is substantially concentric with the outer peripheral magnetic pole 32, and is in the same direction as the moving direction of the substrate 2. Have the same or smaller dimensions and are arranged opposite to each other as shown in FIG. As shown in FIG. 3D, the shutter 4 is a first shutter 41 that opens and closes in the moving direction of the substrate 2 (arrow BB 'direction) and a direction perpendicular to the moving direction (arrow CC' direction). ) And a second shutter 42 that opens and closes.

In such a configuration, the polarity of the tip of the central magnetic pole 31 is S
If the tip poles of the poles and the outer magnetic pole 32 are N poles and the magnetic capacity is arranged so that the outer magnetic pole 32 is larger than the central magnetic pole 31, a tunnel-shaped magnetic line of force between the central magnetic pole 31 and the outer magnetic pole 32. 111 is formed, the plasma 112 is confined, the long track-shaped high density plasma 112 is formed, and the function as magnetron sputtering can be exhibited. Here, since the magnetic capacity of the outer magnetic pole 32 is larger than that of the central magnetic pole 31, the extra magnetic force lines 113 of the outer magnetic pole 32 are guided toward the substrate 2 by the magnetic force lines 114 generated by the excitation of the solenoid coil 36. In this state, a bias voltage is applied to the substrate 2 or, when the substrate 2 is a dielectric, a plasma bias such as a self-bias or a high frequency bias voltage is applied between the plasma potential and the substrate potential so that the substrate 2 side becomes low. The ions inside can be heated and bombarded on the substrate 2.

However, in this state, the ion flux ratio j ₊ / j _m is 0.3.
Although the operating range is limited, the solenoid coil 51 has a smaller dimension in the same direction as the substrate moving direction (arrow A direction) than the outer peripheral solenoid coil 36, but is arranged on the back side of the substrate 2 in the arrow direction 115. The extra magnetic field lines 113 are focused by energizing them to increase the ion flux j ₊ , and the opening of the shutter 4 is narrowed to almost the same as the inner diameter width of the solenoid coil 51 to reduce the spatter particle flux j _m. Therefore, the ion flux ratio j ₊ / j _m can be dramatically increased. For example, when the shutter 4 is opened to 1/4, the ion flux j ₊ is quadrupled by simple calculation, and the sputtering particle flux j _m is 1/4 and the film formation rate is 1/4. The ratio j ₊ / j _m is 16 times. Conventionally, as shown in FIG. 3, the ion focusing solenoid coil 51 and its power supply 7 are not provided, so that the magnetic force lines 113 directed to the substrate 2 are transferred to the shutter 4.
It is not possible to improve the ion flux j ₊ because it cannot be collected in the opening of the ion flux, and therefore the ion flux ratio j ₊
Although the maximum of / j _m is 0.3 to 0.5, it can be increased to 5 to 8 according to the present embodiment.

4 (a) to 4 (d) are views showing the configuration of another embodiment of the present invention, and the same portions as those in FIG. 1 are designated by the same reference numerals. In FIG. 3A, a solenoid coil 52 having a small width is provided on the inner peripheral side of the focusing solenoid coil 51 on the back surface of the substrate 2 so that the solenoid 53 can be switched by a switch 53 and the opening of the shutter 4 can be switched in two steps. It was done like this. Therefore, when the ion flux ratio j ₊ / j _m is good, the opening of the shutter 4 is also used together with the inner circumferential dimension of the solenoid coil 51 by using the solenoid coil 51 having a large width, and the ion flux ratio j ₊ / When j _m is set large, the opening of the shutter 4 may be narrowed accordingly by using the solenoid coil 52 having a small width. The other parts are the first
It is similar to the figure.

FIG. 4 (b) shows an example in which a fixed plate 4'having an opening 4a 'whose opening cannot be adjusted is used instead of the shutter 4 of FIG. 4 (a), and when the operating conditions are predetermined. , This device can also perform ion assist with a high ion flux ratio j ₊ / j _m . Further, FIG. 2B shows a case where the solenoid coil 36 on the target 35 side is also used as the solenoid coil 51 on the rear surface side of the substrate 2.

FIG. 4 (c) shows a case where a permanent magnet 54 is used instead of the solenoid coil 51 of FIG. 4 (b). In FIG. 4 (c), the permanent magnet 54 corresponds to the opening / closing of the shutter 4. Is movable in the same phase in the direction of arrow DD '.

In FIG. 4 (d), an auxiliary solenoid coil 55 is provided on the inner peripheral side of the solenoid coil 51 to adjust and give an exciting current, thereby changing the magnetic field distribution between the openings of the shutter 4 so that the ions are generated. The distribution can be made uniform. When the ion distribution on the center side of the opening of the shutter 4 is large, the exciting direction 115 of the auxiliary solenoid coil 55 is 115.
If the ion distribution on the open end side of the shutter 9 is large, the ion distribution can be averaged by exciting in the same direction as the exciting direction 115 of the solenoid coil 51. .

FIG. 5 is a diagram showing the configuration of another embodiment of the present invention when a bias voltage is applied to the substrate 2. In the figure, the ion flux in the vicinity of the substrate 2 can be adjusted by the magnitude of the exciting currents of the solenoid coil 36 and the solenoid coil 51, but in order to accelerate and hit the substrate 2, the surface of the substrate 2 and plasma
A potential difference must be applied to 112. In the example of FIG. 1 (a), a predetermined negative voltage is applied from the substrate bias power source 10 through the terminal that contacts the substrate 2,
In FIG. 5, a positive bias voltage is applied to the conductive shutter 4 which is insulated from the others, and a part of the shutter 4 is electrically contacted with the plasma 112 so that the plasma 112 is
Is set so that the potential of the surface of the substrate 2 becomes relatively low so that the ion flux is accelerated and collided with the surface of the substrate 2. It is effective when 10 (see FIG. 1 (a)) is difficult to connect.

FIG. 6 shows an embodiment in which the present invention is applied to an apparatus for forming a film on a film-shaped substrate wound on a roll. In the figure, 12 is a film-shaped substrate that moves in the direction of arrow E, 13 is a roller that contacts the substrate 12 and rotates in the direction of arrow F, and 14 is a shutter having an opening in the same direction as the direction of movement of the substrate 12. is there. The configurations of the magnetic pole body 3 on the target 35 side and the magnet body 5 on the back side of the substrate 71 are the same as those shown in FIG. 1. In this case, the ion focusing solenoid 51 of the magnet body 5 is located inside the roller 13. The roller 13 is fixedly arranged on the fixed portion 15 so that only the outer cylindrical portion of the roller 13 can be rotationally moved. The bias voltage may be applied from the bias power supply 10 through the terminal 16 that rotates in contact with the substrate 12. Further, as described with reference to FIG. 5, a positive bias voltage may be applied to the shutter 14.

With this structure, the central magnetic poles 31 of the substantially rectangular shape, which form the magnetic pole body 3 on the rear surface side of the target 35, have different polarities.
The number of magnetic field lines starting from the tips of the outer magnetic pole 32 and the outer magnetic pole 32 is adjusted so that the outer magnetic pole 32 is large and the central magnetic pole 31 is small, and a tunnel-shaped magnetic field 111 is generated between the central magnetic pole 31 and the outer magnetic pole 32. Extra magnetic lines of force 113 that are formed and start from the tip of the outer magnetic pole 32.
Is adjusted to adjust the exciting current of a substantially rectangular solenoid coil 51 arranged on the back surface side of the substrate 2 so as to be directed in a direction substantially perpendicular to the substrate 2 and focused so that the opening of the shutter 4 is substantially solenoid coil 51. as the equivalent to the internal dimensions increase ion flux j ₊ in the vicinity of the substrate 2, sputtered particle flux j _m
Ratio, i.e., so as to take a large ion hula try ratio j ₊ / j _m for the ₊ ion flux j a voltage is applied to the surface or shutter 4 of the substrate 2, and so hit the substrate 2 to accelerate ions Therefore, the tissue structure and crystallinity of the film can be controlled by the ion assisted sputtering method.

〔The invention's effect〕

As described above, according to the present invention, since the ion flux / spatter particle flux and the energy applied to the ions can be independently applied in a wide range, the electric resistance of the film, the specular reflectance, the hardness, the adhesive force, and the denseness It is possible to improve various characteristics such as the degree of smoothness and surface smoothness. Further, the internal stress of the film can be adjusted by giving a combination of ion flux / sputtering particle flux and energy, and the shape of the target is substantially rectangular. Therefore, it is possible to form a substrate having a large size with high productivity. Further, in the case of the conventional reactive sputtering using a DC power supply, the film formation rate is extremely small because it has a small amount of ions, which is not industrially possible.However, according to the method of the present invention, since the amount of ions can be controlled, the reaction It is accelerated, and an extremely excellent effect such that the film forming rate can be improved can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of an apparatus for explaining an embodiment of the ion assisted sputtering method according to the present invention, and FIGS. 2 (a) to 2 (d) are diagrams showing the configuration of the main part of FIG. FIG. 3 is an explanatory view, FIG. 3 is a view showing a conventional device, and FIG. 4 (a)
(D) is sectional drawing explaining the other Example of the ion assisted sputtering device by this invention, FIG. 5, and FIG.
The drawing is a cross-sectional view for explaining still another embodiment of the present invention. 1 ... vacuum container, 2 ... substrate, 3 ... pole body, 4,4 '...
… Shatter, 5 …… Ion focusing magnet body, 6 …… Heater, 7,8,9,10 …… Power supply, 12 …… Substrate, 13 …… Roller, 14
...... Shutter, 15 ...... Fixed part, 16 ...... Terminal, 31 ...... Central magnetic pole, 32 ...... Outer magnetic pole, 33 ...... Yoke, 34 ...... Plasma generation electrode, 35 ...... Target, 36 ...... Magnetic balance Adjusting solenoid coil, 41 ...... first shutter, 42 ......
Second shutter, 51 ... Ion focusing solenoid coil, 52 ... Solenoid coil, 53 ... Switch, 54 ...
Permanent magnets, 55 ... auxiliary solenoid coils, 111 ... magnetic field lines, 112 ... plasma, 113, 114, 115 ... magnetic field lines.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 21/203 S 8719-4M

Claims (2)

[Claims] 1. A pass-through sputtering apparatus for forming a film on a front surface of a substrate while moving a position of a substrate and a target relative to each other, wherein a magnetic pole body is arranged on a rear surface side of the target to form plasma. A magnet body is arranged on the backside of the substrate opposite to the substrate to focus and guide the plasma formed on the target surface to the substrate side, and the plasma is opened and closed between the substrate and the target in the same direction as the moving direction of the substrate. An ion assisted sputtering method comprising providing a shutter to control the opening and closing of the shutter to adjust the ratio of the ion flux reaching the substrate from the target and the sputtered particle flux. 2. A pass-through sputtering apparatus for forming a film on the front surface of a substrate while moving the positions of the substrate and the target relative to each other, wherein a plasma forming means by a magnetic pole body arranged on the rear surface side of the target, and the rear surface of the target. Between the substrate and the target, there is a plasma focusing means by a magnet body which is arranged on the back surface side of the substrate facing the side pole body through the substrate and focuses and guides the plasma formed on the target surface to the substrate side. A shutter having an opening set in the same direction as the substrate moving direction, and a sputtering particle flux adjusting means for controlling the opening / closing of the shutter to adjust the ratio of the ion flux and the sputtering particle flux. Ion-assisted sputtering equipment.