JPH0310071A - Ion-assisted sputtering method and apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ion-assisted sputtering method and apparatus for producing thin films with various functions, and the present invention relates to an ion-assisted sputtering method and apparatus for producing thin films with various functions, and the structure and internal stress of the thin films are suitable for the purpose of use. The present invention relates to an ion-assisted sputtering method and apparatus that can be controlled arbitrarily.

[Conventional Technique #i1 For example, in the process of depositing desired material atoms onto a substrate using a device that combines a vapor deposition device and an ion gun, while hitting the deposited atoms with ions from an ion generator provided separately such as an ion gun ( (This is called ion bombardment, ion peening, or ion assist.Hereafter referred to as ion assist.) When a thin film is formed, the adhesion to the substrate and the deposited thin film increase compared to those without ion assist. It is known that the density is improved and, as a result, a number of functional improvements such as surface hardness, surface roughness, optical reflectance, and electrical resistance can be achieved. This is because ions with kinetic energy collide with the deposited atoms, causing the deposited atoms to move horizontally with respect to the film surface (referred to as migration) and stay in the most stable place, causing the atoms to This is thought to be due to the dense arrangement.

However, even if you aim to achieve the same effect by combining a sputtering device with an ion gun, with current technology, the gas pressure level used in the sputtering device and the gas pressure level used in the ion gun are different, and they operate simultaneously in the same vacuum chamber. That's difficult.

Furthermore, the combination of an ion gun and conventional vapor deposition equipment or sputtering equipment has the drawback of being complicated in structure and expensive.

In addition, a method called bias sputtering has been proposed in which a bias voltage is applied to the substrate to improve various properties of the film, but this method only controls the energy given to the ions, and the amount of ions is controlled. The increase and decrease cannot be controlled. Especially in magnetron sputtering, the amount of ions is extremely small, so even if ion energy is applied, no effect can be expected.

Therefore, instead of using a separate ion source as described above, a negative bias voltage is applied to the substrate by guiding the working gas ions in the plasma that are inevitably generated during sputtering to the vicinity of the substrate by adjusting the magnetic field. B, Window is an attempt to change the structure of a thin film by applying kinetic energy to ions near the substrate during film formation and hitting the atoms deposited on the substrate with the ions (ion assist).
and N.

According to S avv 1des et al., J, Vac, S
ci, Technol.

A4 (2), Mar, /Apt, 1986, p19
It has been proposed since 6.

Another method, as disclosed in Japanese Patent Application Laid-Open No. 63-223173, is to set the magnetic field between the substrate and the target in a cusp magnetic field mode, confine the plasma within this cusp magnetic field, and confine the ions in the plasma. A method has been proposed in which ion assist is provided by applying kinetic energy to ions by applying a negative bias potential to the substrate.

B. Method of Window et al. and JP-A-63-22
Although the method of Publication No. 3173 differs in the means for guiding ions to the vicinity of the substrate, it sputters target atoms using a ring-shaped main plasma confined in a tunnel-shaped magnetic field formed by magnetron sputtering, and at the same time, the method uses a magnetic field near the main plasma to be sputtered. The process involves adjusting and guiding ions near the substrate, applying a bias potential to the substrate to give kinetic energy to the ions, and striking sputtered atoms depositing on the substrate surface, that is, ion assisting, to form a film. are the same.

However, the common drawback of the above is that the position of this main plasma is shifted in the radial direction from the center of the target due to the influence of the magnetic field adjusted to guide ions from the annular main plasma position confined by the tunnel magnetic field for sputtering. The point is that the amount of ions that expand and contract and are guided near the substrate is small. The kinetic energy imparted to the ions can be adjusted by adjusting the voltage applied to the substrate (hereinafter referred to as bias voltage), but the amount of ions can be adjusted by changing the magnetic field by changing the excitation current of the solenoid coil, which confines the main plasma. As a result, the position of the annular main plasma formed on the target surface moves so as to expand and contract in the radial direction from the target center.

In the magnetron sputtering method, there is an S-tangential relationship between the main plasma ring position and the film thickness distribution deposited on the substrate, and the film thickness distribution corresponds to the main plasma ring position. In conventional magnetron sputtering without ion assist, the position of the plasma ring does not move, and in order to increase the area where the film thickness distribution is uniform, the distance between the substrate and the target is adjusted when fishing by boat. However, if the plasma position changes in the radial direction each time the ion amount is adjusted as described above, the distance between the substrate and the target must be adjusted each time the ion amount is set. In the case of an apparatus in which the distance between the substrate and the target is fixed, the area where the film thickness distribution is uniform depending on the amount of ions is limited. Furthermore, if it is desired to adjust the amount of ions at the beginning and during the film-forming operation and to obtain a large area of uniform film thickness, it is necessary to temporarily stop the film-forming operation and adjust the distance between the substrate and the target.

If the distance between the substrate and target is adjusted during film deposition operation, the gas pressure within the vacuum chamber will fluctuate, making steady operation virtually impossible.

The amount of ions that reach the substrate is J◆, the number of particles deposited on the substrate is Jm, and the number of ions that arrive per second per unit area (1 cm') of the substrate is called ion flux (r 1ux). The number of sputtered particles arriving per second per unit area (1 cm") of is called the sputtered particle flux. Also, the ratio of ion flux to sputtered particle flux j◆/j
■ is the ion flux ratio
). The energy for accelerating these ions is defined as acceleration energy E.

The process of bombarding the substrate with ions by combining the ion flux ratio j◆/js and the acceleration energy E will be referred to as ion assist.

When controlling the tissue structure of membranes by ion assist,
The ratio of the amount of ions reaching the substrate per unit area time, that is, the ion flux j◆, and the number of target particles deposited on the substrate, that is, the sputtered particle flux j, that is, the ion flux ratio j◆/j Two important controlling factors are the intestinal value and the kinetic energy E imparted to the ions. However, when the distance between the substrate and the target or the gas pressure is changed in order to enlarge the area of uniform film thickness distribution as described above, the ion flux j◆ on the substrate also changes.

Generally, the larger the distance between the substrate and the target and the higher the gas pressure, the smaller the ion flux j♦.

Furthermore, the movement of the main plasma causes the target particles, ie, the spa γ particle flux j11, to change toward the substrate. This is because, in addition to the difference in film thickness distribution, the intensity of the main discharge plasma also changes. See B for changes in main discharge plasma.

This is clear from the fact that there is a difference in the discharge voltage in Table 5.6.7 of the paper by Window et al.

In other words, in order to control the increase or decrease in the amount of ions, changing the excitation current of the solenoid coil causes a change in the main discharge, changing the energy that impacts the target, and increasing the sputtering rate (
The number of target atoms ejected by one ion) changes, and the deposition rate of target atoms on the substrate also changes. Therefore, due to the movement of the main plasma, the sputtered particle flux j layer changes, and the ion flux ratio j÷lj It becomes complicated and difficult to control the fine membrane tissue structure by controlling the mouth. Therefore, in magnetron sputtering, which forms a film while performing ion assist, the position of the main plasma ring must be fixed so that it does not move in the radial direction.

However, in conventional magnetron sputtering in which the main plasma position does not move, the main plasma is completely confined by a strong tunnel-like magnetic field, and because it is magnetically balanced between the magnetic poles, there are fewer lines of magnetic force directed toward the vicinity of the substrate. ,
There are almost no ions near the substrate, so
Even if a bias voltage is applied to the substrate, no ion assist effect can be expected.

In addition, in the method of Window et al., when trying to control the ion flux j+ due to plasma movement, the sputtered particle flux j■ changes, and as a result, the ion flux ratio j
◆There is a drawback that the lj layer cannot be set to a desired value.

[Problems to be Solved by the Invention] The present invention relates to an ion-assisted magnetron sputtering method and apparatus that improve the above-mentioned drawbacks, and suppress movement of the position of the main plasma ring formed by magnetron sputtering as much as possible.

In addition, it is designed to guide ions to the substrate.

Therefore, it is possible to independently control the ion flux ratio j + / j and its kinetic energy E according to the purpose without affecting the film thickness distribution, and it is possible to adjust the tissue structure and internal stress of the thin film. This is what I did.

Hereinafter, the method and apparatus of the present invention will be explained in comparison with conventional methods.

Figure 7 shows a typical example of the electrode configuration of conventional magnetron sputtering. 1 is a central magnetic pole made of a permanent magnet or a magnetic material, 2 is an outer magnetic pole made of a magnetic material or a permanent magnet, and 4 is a central magnetic pole 1 and an outer periphery. A magnetic yoke magnetically couples the magnetic poles 2; 6 is a target; 8 is a substrate; 11 is a cross-sectional schematic diagram of a tunnel-shaped magnetic field formed between the central magnetic pole 1 and the outer magnetic pole 2; A schematic cross-sectional view of a confined annular plasma is shown.

In FIG. 7, either the central magnetic pole 1 or the outer magnetic pole 2 is a permanent magnet and is magnetically balanced. That is, it is designed so that the number of magnetic flux lines emitted from the central magnetic pole 1 (m flux density x cross section 71) is equal to the number of magnetic flux lines entering the outer magnetic pole 2, making it a complete magnetron. Therefore, the magnetic lines of force form a tunnel-like magnetic field 11 on the upper surface of the target 6, the plasma 14 is completely confined, and the number of ions near the substrate 8 is extremely small.Therefore, in the type shown in FIG. 7, a bias voltage is applied to the substrate. However, since the amount of ions is small, no ion assist effect can be expected.

Figure 8 shows B, F in the paper by Window et al.
ig.

This is one of the ones shown in 2. In Figure 8, 12
is a schematic diagram of lines of magnetic force directed in a direction approximately perpendicular to the substrate 8, and other symbols are the same as in FIG. It is made magnetically unbalanced.

The saturation magnetic flux (saturation magnetic flux density x cross-sectional area) used in the present invention refers to the maximum number of magnetic flux lines that can pass through (permeate) one magnetic pole, and in the case of soft magnetic materials, the maximum permeable magnetic flux. Number of magnetic flux lines (
(magnetic permeability x cross-sectional area).

In the case of a permanent magnet, the number of magnetic flux lines generated from itself (magnetic flux density ×
Also, being magnetically saturated means that it is filled with magnetic flux up to the above-mentioned saturation magnetic flux.

In Figure 8, the central magnetic pole l is magnetically saturated;
Even if all the magnetic flux lines emitted from the central magnetic pole 1 enter the outer magnetic pole 2, the outer magnetic pole 2 is not magnetically balanced, and the outer magnetic pole 2
has a magnetic margin, and the lines of magnetic force 12 that are substantially perpendicular to the substrate 8 bypass the substrate 8 from other than the tip of the central magnetic pole 1 and head toward the outer magnetic pole 2, and as a result, the magnetic field lines 12 near the substrate 8 can lead to. However, in the case shown in Figure 8, the magnetic pole is composed only of permanent magnets and magnetic materials, so the amount of ions is constant and the main plasma does not move.
It is not possible to control the increase or decrease of the ion amount jm.

FIG. 9 is another example shown in Fig. 2 of the paper p197 of the same <B, Window et al.

In FIG. 9, l is a central magnetic pole made of soft magnetic material, 2 is an outer magnetic pole made of soft magnetic material, 4 is a magnetic yoke that magnetically couples the central magnetic pole 1 and outer magnetic pole 2, 6 is a target, and 7 is an outer magnetic pole. Solenoid coil placed nearby, 8 is the board, 17
11 is a cross-sectional schematic diagram of a tunnel-shaped magnetic field formed between the central magnetic pole 1 and the outer magnetic pole 2; 12 is a schematic diagram of lines of magnetic force directed in a direction substantially perpendicular to the substrate; 13 is a schematic diagram showing the excitation direction of the solenoid coil 7, and 14 is a schematic cross-sectional diagram of the annular main plasma confined in the tunnel magnetic field 11.

18 is a schematic diagram showing the excitation direction of the solenoid coil 17. In FIG. 17 until the central magnetic pole 1 is magnetically saturated, all lines of magnetic force emitted from the central magnetic pole l enter the outer magnetic pole 2 to form a tunnel-shaped magnetic field 11 and confine the annular main plasma 14. In this state, the outer magnetic pole 2 has a large saturation magnetic flux, so it is not magnetically saturated and is in magnetron mode.
Next, when the solenoid coil 7 is excited in the direction indicated by the reference numeral 13, lines of magnetic force 12 substantially perpendicular to the substrate 8 are directed toward the outer magnetic pole 2.

As a result, ions in the plasma that are not magnetically confined in the vicinity of the outer magnetic pole 2 are guided to the vicinity of the substrate 8. Therefore, by adjusting the excitation current of the solenoid coil 7, the amount of ions can be adjusted, and by applying a bias voltage to the substrate 8, it is possible to give kinetic energy to the ions and perform ion assist. However, since each magnetic pole is made of a magnetic material, if the excitation current of the solenoid coil 7 is changed when changing the amount of ions, the leakage magnetic field mode of the central magnetic pole 1 tends to change, and the position of the main plasma is shifted to the target. 6 Move radially from the center. For the type shown in FIG. 9, the excitation r of the solenoid coil 17
FIG. 11 shows the ion distribution state when the excitation current of the solenoid coil 7 is varied while keeping the ji current constant at -1OA, and FIG. 12 shows the film thickness distribution and plasma position.

The main conditions in this case are that the target 6 is oxygen-free copper, the distance between the substrate 8 and the target 6 is 60 mm, the outer diameter of the outer magnetic pole 2 is φ160 mm, the outer diameter of the substrate 8 is φ120 mm, and the gas pressure is 2 mTorr (At ), the discharge current is DCo
, 5AXlsin, the current of the solenoid coil 17 is constant at -10A, and the excitation current of the solenoid coil 7 is +8A, +6A.

■ Figure 11 shows the ion current distribution when changing to three types of +2A, and Figure 12 shows the film thickness distribution and plasma position. From Figure 11, it is possible to increase or decrease the number of ions by adjusting the solenoid coil 7. It is.

However, as shown in FIG. 12, the amount of movement of the plasma position in the radial direction is large, and it can be seen that this effect causes a large difference in the film thickness distribution.

FIG. 1O shows another conventional method disclosed in Japanese Unexamined Patent Publication No. 63-223173, where l is the central magnetic pole.

2 is an outer magnetic pole, 4 is a magnetic yoke that magnetically couples the central magnetic pole l and the outer magnetic pole 2, 6 is a target, and 19 is a substrate 8.
Second solenoid coil near the back.

8 is a substrate, 17 is a first solenoid coil for exciting the central magnetic pole l, and 21 is a third solenoid coil arranged near the outer periphery of the substrate 8.
11 is a schematic cross-sectional view of a tunnel-shaped magnetic field formed between the central magnetic pole 1 and the outer magnetic pole 2; 12 is a schematic diagram of magnetic lines of force extending from the central magnetic pole l in a direction substantially perpendicular to the substrate 8; 20 14 is a schematic diagram showing the excitation direction of the second solenoid coil 19, 14 is an annular main plasma confined in the tunnel magnetic field 11, and 22 is a schematic diagram showing the excitation direction of the third solenoid coil 21. The solenoid coil 17 plays the role of forming the tunnel magnetic field 11, and the second solenoid coil 19 is connected to the substrate 8 from the central magnetic pole l.
The third solenoid coil 21, which plays the role of guiding the magnetic field lines 12 directed toward the substrate in a direction perpendicular to the substrate, directs the magnetic field 11 that confines the plasma in a tunnel shape to the target 6@
A cusp magnetic field is formed by these solenoid coils 17, 19° 21, which play the role of strongly confining the main plasma 14 by being pressed against the main plasma 14. The amount of ions can be increased or decreased by changing the excitation current of the second solenoid coil 19 alone or in combination with other solenoid coils to increase or decrease the vertical component magnetic field directed toward the substrate 8. Kinetic energy can be imparted to the ions by applying a bias voltage to the substrate 8.

However, in this method, as in the case of FIG. 9, when the magnetic field is adjusted, the main plasma 14 moves in the radial direction.
In FIG. 10, if the second solenoid coil 19 is strengthened, the main plasma 14 moves toward the center. If the third solenoid coil 21 is strengthened, the main plasma 14 will move toward the center. As the main plasma 14 moves, the film thickness distribution mode also changes as described above. In addition, in the case of FIG. 1O, among the magnetic lines of force 12 emitted from the central magnetic pole l, those directed toward the outer magnetic pole 2 are crimped to the target 6 side by the third solenoid coil 21, and the lines of magnetic force 12 directed toward the substrate 8 are pressed into the second It is guided to the board 8 side by a solenoid coil 19. This method cannot be applied to applications where the amount of ions j+ is small and the ion flux ratio j◆/jm needs to be large.This means that the saturation magnetic flux of the central magnetic pole 1 in the paper by B. It belongs to those whose saturation magnetic flux is larger than No. 2, and it is described in 3.4.5 of Table I that the amount of ions is small. That is, in the conventional magnetron sputtering method that can perform ion assist as shown in FIGS. ◆Each time the increase or decrease of is adjusted, the main plasma position moves a large amount, and as a result, the conditions for making the film thickness distribution uniform must be adjusted.Conversely, the conditions for making the film thickness distribution uniform For example, it is not possible to control the increase or decrease in the amount of ions while keeping the distance between the substrate 8 and the target 6, the gas pressure, etc. constant.

When hitting the substrate 8 with ions, the ion assist effect varies depending on the ratio of the number of sputtered particles jm per unit area per unit time and the number j◆ of ions, that is, the ion flux ratio j+/jm and the way the acceleration energy E is applied. For example, when the ion flux ratio J+/j■ is small and the kinetic energy E is large, and when the ion flux ratio J+/1m is large and the kinetic energy E is small, the various properties of the resulting film will be different. The characteristics will be different. In particular, with regard to the internal stress of the thin film, when the ion energy E is increased, the internal stress of the film shifts significantly toward the compressive stress side.

In other words, in order to be able to handle a wide variety of functional thin films,
A common drawback of conventional techniques is that the ion flux ratio j◆/Js+ must be controlled over a large range. , the number i of sputtered particles
m also changes, and as a result, the ion flux ratio j
◆/jm cannot be controlled to increase or decrease.

The reason for this is that in the case shown in FIGS. 9 and 10, the magnetic pole forming the main plasma 14 is directly adjusted by a solenoid coil. Also.

In the case shown in FIG. 10, the amount of ions generated j◆ is small, and there are restrictions on those in which the ion flux ratio j◆/J intestine is desired to be large.

Therefore, one aspect of the present invention is to make the position of the main plasma 14 difficult to move, and to increase the amount of ions j+.
Suppressing changes in film thickness distribution and reducing ion flux ratio
◆/j quantity control g# range can be widened.

[Means and effects for solving the problem] The present invention provides a new intermediate magnetic pole between the central magnetic pole and the outer circumferential magnetic pole, and arranges the polarities of these magnetic poles alternately, so that the intermediate magnetic pole and the outer circumferential magnetic pole The magnetic circuit formed by the center magnetic pole and the intermediate magnetic pole are configured to form a high-density main plasma that increases the saturation magnetic flux of one magnetic circuit and contributes to sputtering, and the magnetic circuit of the other magnetic circuit The saturation magnetic flux of the target was made small to form a low-density sub-plasma that does not contribute to sputtering, thereby forming a double annular plasma on the target. In other words, a secondary plasma is formed on the inner or outer periphery of the main plasma to increase the amount of ions, and the plasma is fixed by using two adjacent magnetic poles that form the main plasma as permanent magnets with large saturation magnetic flux. One of the saturation magnetic fluxes of the permanent magnets that form the plasma is made larger than the other to make it magnetically unbalanced, and other magnetic poles adjacent to this magnetic pole are magnetically saturated, so that the permanent magnet has the maximum saturation magnetic flux. Generates extra lines of magnetic force from the magnetic poles.

When a solenoid coil placed near the outer periphery of these magnetic poles is excited in a direction that strengthens these extra lines of magnetic force, the other magnetic pole is magnetically saturated, so it does not go in the direction of this magnetic pole, but bypasses the vicinity of the board. A magnetic field distribution is formed in a direction substantially perpendicular to the substrate.

In addition, the pair of magnetic poles that form the main plasma are permanent magnets with large saturation magnetic flux, and one magnetic pole is magnetically saturated to make it less susceptible to the excitation of the solenoid coil. Movement is likely to occur.

Therefore, ions necessary for ion assist can be guided to the substrate without moving the main plasma position.

Regarding the energy for hitting the substrate, by adjusting the bias voltage of the substrate in the prior art, it is possible to adjust the kinetic energy given to the ions.

[Example] Examples of the present invention are shown in FIG. 1, FIG. 2, FIG. 4, and FIG. 6, and an example that is similar to these examples and cannot achieve the present invention is shown in FIG. and shown in Figure 5.

In Figures 1 to 6, l is a solid or hollow central magnet made of a soft magnetic material or a permanent magnet, 2 is an outer magnetic pole made of a permanent magnet or a soft magnetic material, and 3 is a central magnetic pole l and an outer magnetic pole 2. The outer magnetic pole 2 and the intermediate magnetic pole 3 are annular or oblong annular. 4 is a magnetic yoke that magnetically couples the central magnetic pole 1 and the intermediate magnetic pole 3; 5 is a magnetic yoke that magnetically couples the intermediate magnetic pole 3 and the outer circumferential magnetic pole 2; 6 is a target;
7 is a solenoid coil for controlling the amount of ions arranged near the outer magnetic pole 2; 8 is a substrate; 9 is an auxiliary solenoid coil; 10 is a tunnel-shaped magnetic circuit formed by the magnetic circuit between the intermediate magnetic pole 3 and the outer magnetic pole 2; A schematic diagram of lines of magnetic force; 11 is a schematic diagram of tunnel-shaped lines of magnetic force formed by the magnetic circuit between the central magnetic pole 1 and the intermediate magnetic pole 3; 12 is a schematic diagram of lines of magnetic force running substantially perpendicular to the substrate 8; 13 is a solenoid; coil 7
14 is a schematic cross-sectional diagram of the annular main plasma, 15 is a schematic cross-sectional diagram of the sub-plasma, 16 is a schematic diagram showing the direction of excitation.
shows a schematic diagram showing the excitation direction of the auxiliary solenoid coil 9.

In Figures 1 to 6, tunnel magnetic lines of force to, it
The solid line indicates the magnetic intensity is large, and the broken line indicates the small magnetic intensity. Those with high magnetic strength strongly confine plasma and form main plasma 14, and those with weak magnetic strength weakly confine plasma and form sub-plasma 15.

The main plasma contributes to sputtering, and the sub-plasma hardly contributes to sputtering and is a plasma for ion formation.

The main plasma is shown by diagonal lines, and the secondary plasma is shown by broken points.

FIG. 1 shows an embodiment of the present invention, in which the saturation magnetic flux of each magnetic pole is set such that the outer magnetic pole>intermediate magnetic pole) is the center magnetic pole, and the saturation magnetic flux of each magnetic pole is set such that the outer circumferential magnetic pole>intermediate magnetic pole+center magnetic pole. The main plasma is formed on the outer circumferential side of the target 6, the sub-plasma is formed on the inner side, and magnetic flux lines 1□2 directed toward the substrate 8 are emitted from the outer circumferential magnetic pole 2. For this reason, the outer magnetic pole 2 and the central magnetic pole 3 that form the main plasma
is made of strong permanent magnet. In Fig. 1, the central magnetic pole 1 is a permanent magnet with a small saturation magnetic flux, but it may also be made of a soft magnetic material.The central magnetic pole 1 can form a weak tunnel magnetic field 11 between it and the intermediate magnetic pole 3 to form sub-plasma. That's what I do.

In order to generate magnetic flux lines 12 directed from the outer magnetic pole 2 toward the substrate 8, the saturation magnetic flux of the outer magnetic pole 2 is made larger than the saturation magnetic flux of the intermediate magnetic pole 3, so that the intermediate magnetic pole 3 is in a magnetically saturated state. Therefore, the extra magnetic flux of the outer magnetic pole 2 cannot be directed to the intermediate magnetic pole 3, but instead goes in a direction that bypasses the substrate 8. At this time,
When the solenoid coil 7 is excited in the direction of the arrow 13 shown in FIG. On the other hand, the magnetic flux lines 11 that weakly confine the secondary plasma also approach the direction in which confinement is released, that is, toward the substrate 8.

At this time, the magnetic flux lines lO that confine the main plasma form a strong magnetic field, and because a permanent magnet is used for the intermediate magnetic pole 3 and the saturation magnetic flux is smaller than the outer magnetic flux 2, the magnetic flux line lO becomes stronger. Since it is saturated, the movement of the main plasma in the radiation direction can be made extremely small under the influence of the excitation of the solenoid coil 7.

Furthermore, when the solenoid coil 7 is excited in the direction opposite to the arrow 13 in FIG. Tunnel magnetic field on the top surface of target 6
cannot be formed, and as a result, the secondary plasma disappears, resulting in a normal magnetron mode with only the main plasma. Also at this time, the movement of the main plasma position in the radial direction is small.

That is, in the present invention shown in FIG. 1, by adjusting the magnitude and direction of the excitation current of the solenoid coil 7, the amount of ions guided to the vicinity of the substrate 8 can be controlled to increase or decrease. The kinetic energy of the ions hitting the substrate 8 can be controlled by applying a negative bias voltage to the substrate 8 and adjusting the increase or decrease of this voltage. Note that it is also possible to ground the substrate 8 and use a self-bias voltage to keep the kinetic energy given to the ions constant. In addition, the board 8
If the anode is placed in electrical contact with the plasma generated between the substrate 8 and the target 6, and a positive voltage is applied to the anode to relatively increase the potential of the plasma itself, the substrate 8 It is possible to give kinetic energy to ions even when it is grounded. In short, when the potential between the substrate 8 and the plasma becomes relatively low on the substrate 8 side, ions are accelerated toward the substrate 8.

Regarding the one in Figure 1, Figure 13 shows the ion current distribution when the excitation current of the solenoid coil 7 is changed, and Figure 14 shows the results of investigating the film thickness distribution and plasma position. 6 is oxygen-free copper, the distance between the substrate 8 and the target 6 is 60 mm, and the outer diameter of the outer magnetic pole 2 is φ180.
mm, the outer diameter of the substrate 8 is φ120 mm, and the gas pressure is 2 mTo.
rr, the discharge current is DCo, 5AX1min, and the current of the solenoid coil 7 is -4A, ■±OA, ■÷4A
Changed to three types. From this, it can be seen that the plasma position moves less than the conventional ones shown in Figs. 9 and 10.
Moreover, it can be seen that the ion amount can be adjusted over a wide range.

In Figure 2, the saturation magnetic flux of each magnetic pole is defined as central magnetic pole>intermediate magnetic pole) outer magnetic pole, and central magnetic pole>intermediate magnetic pole+outer magnetic pole.
This is the case where the main plasma 14 is formed on the inner peripheral side of the sub plasma 15.

In FIG. 2, the intermediate magnetic pole 3 and the central magnetic pole 1 are made of strong permanent magnets in order to increase the saturation magnetic flux that forms the main plasma. The central magnetic pole 1 is hollow and has a large area in order to increase the saturation magnetic flux. Magnetic field lines 1 toward the substrate 8
2 to the magnetic pole on the side not adjacent to the sub-plasma, that is, the second
In the figure, in order to emit from the central magnetic pole l, the saturation magnetic flux of the central magnetic pole l is set larger than the saturation magnetic flux of the intermediate magnetic pole 3, so that the saturation magnetic flux of each magnetic pole becomes central magnetic pole>intermediate magnetic pole>outer magnetic pole. In this type, the amount of plasma movement is small, but the amount of ions is smaller than that shown in FIG. 1 in which the solenoid coil 7 is excited in the direction opposite to the direction of arrow 13.

Therefore, it can be applied only to those that require a small amount of ions.

3 and 5 are shown with the direction 13 in which the solenoid coil 7 is energized reversed from those shown in FIGS. 1 and 2, respectively, and a main plasma and a sub-plasma are formed. However, if the solenoid coil 7 is strengthened in an attempt to increase the amount of ions, the secondary plasma will disappear, and if the solenoid coil 7 is weakened in the direction of decreasing the ion amount, a secondary plasma will be formed. In other words, the adjustment range of the ion amount is small, and as it is, it is not suitable for ion assist.

FIG. 4 shows an improvement of FIG. 3, and FIG. 6 shows an improvement of FIG. 5.

Figure 3 shows the saturation magnetic flux of each magnetic pole (middle magnetic pole>outer magnetic pole).
Central magnetic pole, and intermediate magnetic pole〉outer magnetic pole + central magnetic pole,
The intermediate magnetic pole 3 and the outer peripheral magnetic pole 2 are used as permanent magnets, and a main plasma is formed between them, and a sub-plasma is formed between the intermediate magnetic pole 3 and the central magnetic pole 1. The lines of magnetic force toward the substrate 8 are the intermediate magnetic pole 3 with the maximum capacity.
It occurs more. In this type, when the magnet is excited so as to strengthen the lines of magnetic force directed toward the substrate 8, the outer circumferential magnetic pole 2 and the central magnetic pole 3, which have different magnetic properties, are weakened. Since the outer magnetic pole 2 is a strong permanent magnet, its influence is small, but the weak magnetic lines of force generated from the central magnetic pole 1, which form the sub-plasma, are suppressed and the sub-plasma disappears.Therefore, the amount of ions can be increased. On the other hand, if the solenoid coil 7 is excited in the opposite direction to reduce the ion amount, a secondary plasma will be formed and the ion amount cannot be reduced. Not on point.

Therefore, as shown in FIG. 4, the above problem can be solved by providing a solenoid coil 9 around the outer periphery of the central magnetic pole l and applying excitation in the opposite direction to the excitation direction 13 of the solenoid coil 7.

Figure 5 shows the saturation magnetic flux of each magnetic pole (intermediate magnetic pole>center magnetic pole).
The outer magnetic pole is made to be an outer circumferential magnetic pole, and the intermediate magnetic pole is made to be a central magnetic pole + an outer circumferential magnetic pole.The intermediate magnetic pole 3 and the central magnetic pole I are used as strong permanent magnets, and the main plasma is formed between them, and the intermediate magnetic pole A sub-plasma is formed between the magnetic pole 3 and the outer magnetic pole l. The central magnetic pole l is hollow and has a large cross-sectional area in order to increase the saturation magnetic flux.

Lines of magnetic force directed toward the substrate 8 are generated from the intermediate magnetic pole l.

In order to increase the amount of ions, when the solenoid coil 7 is excited so that the intermediate magnetic pole 3 becomes stronger, the magnetic poles adjacent to it are weakened, and when increasing the amount of ions, the outer magnetic pole 2 The sub-plasma formed between the magnetic pole 3 and the intermediate magnetic pole 3 disappears, and the increase in the amount of ions becomes immeasurable. Therefore, this type also has a small amount of ion adjustment and is not practical as an electrode structure for ion-assisted sputtering.

Therefore, as shown in FIG. 6, a solenoid coil 9 is provided near the outer magnetic pole 2, and the excitation direction 13 of the solenoid coil 7 is
The above problem can be solved by applying excitation in the opposite direction.

FIG. 15 shows an example in which the solenoid coil 7 shown in FIG. 1 of the present invention is excited in the direction of the arrow, and the ion flux ratio j◆/Jm is varied to evaluate the density of the film. The operating conditions are as follows: The target 6 is made of oxide-free copper (Cu), the gas pressure is 20 mTarr, the distance between the substrate 8 and the target 6 is 60 mm, and the substrate bias voltage is - It is 100V. When the ion flux ratio j◆/j is increased, the resistivity ρ becomes smaller. Furthermore, the density of the film and the electrical resistance are closely related, as shown in the results shown in Figure 15.

It can be seen that ion assist improves the density.

Figure 16 shows the bending of the substrate (
This figure shows the operation results showing the change in internal stress calculated from the residual radius of curvature. From the results in Figure 16,
It can be seen that the internal stress can be adjusted by giving the ion flux ratio j♦/J+w.

That is, the ion-assisted sputtering method of the present invention makes it possible to control the structure and internal stress of a film, and to form a dense film with low internal stress. In order to realize these, it is necessary to be able to adjust the ion amount j÷ over a large range.

Measures for this purpose will be explained below.

As a result of the investigation using the examples shown in Figs. 1 to 6, it was possible to increase the amount of ions by forming a main plasma for sputtering and a sub-plasma for ion formation that does not contribute to sputtering, and to adjust the magnetic field. In order to prevent the main plasma from moving in the radial direction when performing this process, the magnetic poles that form the main plasma are made into strong permanent magnets, and magnetic lines of force are formed in a direction approximately perpendicular to the substrate 8 to direct ions to the vicinity of the substrate 8. In order to guide the main plasma, the saturation magnetic flux of one of the permanent magnets forming the main plasma is increased to make it relatively unbalanced, and
In order to saturate other magnetic poles, the saturation magnetic flux of each magnetic pole is set to the maximum saturation magnetic flux magnetic pole > the sum of other magnetic poles, and when the solenoid coil is excited to increase ions, a sub-plasma is formed and ions are decreased. At this time, the secondary plasma can be extinguished and the magnetron mode can be established.

With the magnetic pole arrangement described above, the amount of ions in ion-assisted sputtering can be adjusted by adjusting the solenoid coil.

By applying kinetic energy to these ions using conventional techniques such as substrate bias, it is possible to give migration to the deposited particles while hitting the substrate with the ions while sputtering atoms are being deposited, and to arrange the deposited atoms in the most stable position. By combining this and the kinetic energy applied thereto, thin films with various desired tissue structures can be formed under conditions with good film thickness distribution.

In addition, by combining the gas pressure with the above ion assist conditions, the internal stress of the film generated during film formation can be shifted to the compression side by bombarding the film with ions, for example, reducing the stress of a thin film with large tensile stress. is also possible.

In the above embodiment, the case where there is one solenoid coil was explained, but in the present invention, for the same purpose, a plurality of solenoid coils may be used, and the magnetism of the magnetic poles shown in the embodiment may be reversed. However, the effect is the same. In addition, since the central magnetic pole generally cannot achieve a large saturation magnetic flux due to its dimensions, a permanent magnet and a solenoid coil may be combined to supplement this.Also, if a magnetic circuit is installed, the desired value may not be achieved. Alternatively, a separate solenoid coil may be provided to adjust these.

[Effects of the Invention] In the present invention, as described in the claims, it is possible to control the structure and internal stress of the film, and it is possible to form a dense film with low internal stress. Furthermore, the movement of the generated main plasma in the radial direction can be kept extremely small, and the amount of ions can be adjusted over a wide range.

[Brief explanation of the drawing]

Figures 1, 2, 4 and 6 are electrode configuration diagrams for explaining different embodiments of the present invention, and Figures 3 and 5 are similar to Figures 1 and 2, respectively. Figures 7 to 10 are electrode configuration diagrams to explain a case in which an unfavorable result is obtained using a similar device; FIG. 11 is a diagram showing the ion current distribution state in the case shown in FIG. 9, FIG. 12 is a diagram showing the film thickness distribution state and plasma position in the case shown in FIG.
Fig. 3 is a diagram showing the ion current distribution state in the case shown in Fig. 1, Fig. 14 is a line diagram showing the film thickness distribution state and plasma position in the case shown in Fig. 1, and Fig. 15 is a diagram showing the state of the film thickness distribution and plasma position in the case shown in Fig. FIG. 16 is a diagram showing how the electrical resistivity changes with respect to the ion flux ratio in the case shown in FIG. 1. FIG. 1... Central magnetic pole, 2... Outer magnetic pole, 3... Intermediate magnetic pole, 4, 5... Magnetic yoke 6... Target. 7.9.17, 19.21...Solenoid coil, 8
...Substrate, 10.11.12...Schematic lines of magnetic force, 13.16.1
8,20.22... Excitation direction. 14... Main plasma, 15...
Vice plasma. '$1 Figure 2

Claims (2)

[Claims] (1) At least two magnetic poles with different dimensions are arranged at a distance from each other on the outer periphery of a central magnetic pole so that their polarities alternate in the radial direction from the center, and are formed by adjacent magnetic poles with different polarities. Due to multiple tunnel-like magnetic fields,
A plurality of plasmas are formed, at least one of which is a high-density main plasma that can be sputtered, and at least one other is a low-density sub-plasma that does not contribute to sputtering. 2
A permanent magnet has magnetic poles of Excess magnetic flux lines generated from the magnetic poles of the magnet are directed in a direction substantially perpendicular to the substrate by adjusting the excitation current of at least one solenoid coil disposed near the outer periphery of the magnetic poles, thereby adjusting the amount of ions directed toward the vicinity of the substrate. , an ion-assisted sputtering method that deposits a film by adjusting the potential difference between the substrate and the plasma and adjusting the kinetic energy given to the ions. (2) At least two magnetic poles, each consisting of an intermediate magnetic pole and an outer peripheral magnetic pole, each having different dimensions, are arranged at a distance from each other on the outer periphery of the central magnetic pole so that their polarities alternate in the radial direction from the center, and at least One of the outer magnetic poles and the center magnetic pole is made of a permanent magnet with a large saturation magnetic flux, the other magnetic pole is made of a permanent magnet with a small saturation magnetic flux or an orbital magnetic material, and the central magnetic pole, intermediate magnetic pole, and outer magnetic pole are made of a permanent magnet with a small saturation magnetic flux. are magnetic poles with different saturation magnetic fluxes, and among these three types of magnetic poles, the one with the largest saturation magnetic flux is made larger than the sum of the saturation magnetic fluxes of the other two types of magnetic poles, and the saturation magnetic flux is the second largest. An ion-assisted sputtering device with a large magnetic pole that can be magnetically saturated and a solenoid coil for controlling the amount of ions placed near the outer magnetic pole.