JPH02111878A - Sputtering device - Google Patents

Abstract

PURPOSE:To obtain large intensity of a magnetic field and to enhance film forming velocity and to extend the controlling range of sputtering by constituting a target of a plurally divided annular body and forming a magnetic field generating means of the individual plural constitutions according to the divided parts. CONSTITUTION:A target arranged in a vacuum chamber 91 is divided into a plurality of targets (1-8) and the whole body is made an annular body. A plurality of power sources 10-80 correspondent to the respective targets 1-8 are connected therewith respectively. A magnetic field generating means consisting of the combination of permanent magnets 96, 97, a yoke part 95 having soft magnetism and a solenoid coil 94 is provided to the rear sides of the respective targets 1-8. As this magnetic field generating means, an annularly nearly continued closed magnetic field is formed by both the north poles arranged in the nearly whole range of the outer edge parts 97b of the targets 1-8 and the south poles arranged to the inner edge parts 96a. Plasma is trapped in this magnetic field. When a plurality of independent electromagnet power sources 12-17 are controlled, the intensity of respective magnetic fields in the divided parts of the targets 1-8 can be controlled. Thereby consumption of the targets can be uniformized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sputtering apparatus, and more particularly to a magnetron type sputtering apparatus with an improved cathode structure.

[Prior art]

Sputtering technology is a technology that generates a glow discharge of Ar or the like in a low-pressure atmosphere, causes ions in the plasma to collide with a cathode target, knocks out atoms from the target material, and forms a thin film of desired atoms on a substrate. Widely used industrially. In particular, it forms a magnetic field component on the target parallel to the target plane (surface),
The magnetron sputtering method in which the electric field and the magnetic field are substantially orthogonal is a useful method because it has a high film formation rate. Conventional magnetron-type sputtering equipment includes a magnetic field generation stage incorporating a permanent magnet or electromagnet with a cathode located close to the back surface of the target material. FIGS. 6 and 7 schematically show the basic structure of a conventional magnetron type sputtering apparatus.

The cathode 100 common to FIGS. 6 and 7 each has a circular target 101 of a film forming material, and is equipped with a permanent magnet 102 to enable magnetron discharge. The shield portion 103 and a chamber (not shown) are at ground potential, and the target 101 is connected to a sputtering power source 104 outside the chamber. Substrate 10
5 is fixed to a planetary jig 106a that rotates above the target in FIG. 6, and to a rotating substrate holder 106b in FIG. 7, respectively. The planetary jig 106a is used for all the boards 105 to which a plurality of boards are attached.
The structure is designed to rotate around its axis so that the thickness distribution of the thin film deposited on it is uniform. The apparatus shown in FIG. 7 is provided with a movable and adjustable film thickness distribution correction plate 107 between the rotating substrate holder 106b and the target 101, in order to make the film thickness distribution of the deposited film on the substrate 105 uniform. Such efforts have been made.

Furthermore, recently, co-sputtering (Co-S
There is a sputtering apparatus equipped with a plurality of electrodes called a sputtering apparatus. Fig. 8 shows the outline. This device is basically the same as the one shown in FIG. 7, but for example, the cathode 100 is composed of two circular sputtering electrodes, each of which is made of a different material, a1 and a substance. The completed target l01a,
101b, which are arranged at predetermined intervals. Then, a plurality of substrates 105 are placed in the rotating substrate holder 1.
A thin film of a mixture of substances a and b is formed on the substrate 105 while the substrate 105 is fixed on the substrate 105 and rotated. The composition of the mixed thin film can be changed by controlling the ratio of sputtering powers input from the sputtering power sources 104a and 104b. In order to make the composition distribution uniform over the entire surface of the substrate 105, a film thickness distribution correction plate 10 is provided.
7a and 107b are arranged. As can be seen from the above, in the conventional apparatus, in order to make the film thickness distribution uniform, the substrate is simply rotated, and the film thickness distribution correction plate 107a
, 107b, or a method of film formation using a complicated rotational film formation method such as rotation and revolution.

However, according to the conventional method, relying too much on mechanical operating structures to achieve film thickness uniformity is undesirable from the viewpoint of cleanliness within the vacuum chamber, especially in the apparatus shown in FIG. The work of attaching a board to a moving member such as a planetary jig is complex, difficult to automate, and has low productivity. In addition, the drive mechanism is complicated and the equipment cost is high, and there are also problems in maintainability. Furthermore, in the conventional cathode structure, the distance between the substrate mounted on a planetary jig as shown in FIG. 6 and the sputtering source is generally required to be at least about 400 mm or more in order to make the film thickness distribution uniform. Therefore, it is difficult to increase the film deposition rate by reducing the distance, and the longer the distance, the lower the energy of the sputtered particles, resulting in poor adhesion to the substrate, and the sputtering during film formation. This method has a drawback in terms of the production process, in that particles and residual gas components tend to form unexpected bonds, making it impossible to form a highly pure film. Further, the adjustment of the film thickness distribution correction plate used in the apparatuses shown in FIGS. 7 and 8 is complicated, and there is a drawback that the adhesion efficiency to the substrate is greatly reduced due to blocking of sputtered particles.

Furthermore, Japanese Patent Laid-Open No. 199860/1983 discloses a method for forming a high-quality mixed thin film without relying heavily on mechanical operations such as the above-mentioned planetary and film thickness distribution correction plates. This method controls the excitation current of an electromagnetic coil installed on the back side of a target in which different types of materials are arranged in a ring shape, and magnetically moves the position of the ring-shaped plasma (erosion area) on the target surface. This method attempts to form a mixed thin film with a predetermined composition ratio of materials on a substrate. However, in the conventional apparatus as typified by JP-A-58-199860, in order to form the evaporation region 120 (erosion region) of the target 101C shown in FIG. As shown in the figure, a device is used that incorporates a permanent magnet, an electromagnet, or a magnetic field generating means that is a combination of these for generating a leakage magnetic field 110 that is substantially parallel to the surface of the target 01c.

Here, the leakage magnetic field 110 on the surface of the target 101c
Since the strength of the magnetic field can be adjusted appropriately according to the material and thickness of the target material, it has been considered to utilize the magnetic field by an electromagnetic coil having a solenoid coil wound concentrically around the center of the target as shown in FIG. 9. In this case, the electromagnetic power sources are, for example, a power source 114 for the center coil 111 and a power source 115 for the outer coil 112, and the magnetic field strength is adjusted by the two power sources, either uniformly set over the entire target surface or by varying the strength. It also changed the whole thing uniformly. A disadvantage of this method is that as the radius of the target 101C increases, the radius of the solenoid coils 111 and 112 increases accordingly. At this time, if the amperage of the solenoid coils 111 and +12 is the same as when the diameter is small, the magnetic flux density will decrease, and the magnetic field strength will therefore become weaker.

On the other hand, if it is desired to obtain the same magnetic field strength even when the diameter of the target 101C increases, it is necessary to increase the number of turns of the solenoid fills 111 and 112 or increase the coil current. However, when the target diameter is large and the space in which the coil can be wound is relatively narrow, or when a ferromagnetic material is used as the target material, the ferromagnetic material affects the magnetic flux, resulting in a strong magnetic field strength. If necessary, i.e. when using a ferromagnetic target,
Since ferromagnetic materials have high magnetic permeability, most of the lines of magnetic force coming out of the magnetic poles pass through the inside of the target, resulting in a lack of leakage magnetic flux parallel to the target surface required for magnetron sputtering. Therefore, when using a ferromagnetic target,
It is necessary to apply a magnetic field strong enough to exceed the saturation magnetic flux of the target itself and cause further leakage magnetic flux to appear on the target surface. In such cases, sufficient magnetic field strength cannot be obtained using conventional methods. Furthermore, even if a large magnetic field strength is obtained, the cost of equipment and running costs will increase, and the controllability of film composition in forming a mixed thin film as shown in JP-A-58-199860 will be affected. There was a section.

(Objective of the Invention) The object of the present invention was made in view of the various problems mentioned above, and it is possible to achieve uniformity of film thickness without relying heavily on mechanical operation means, and to apply a large magnetic field. The purpose of the present invention is to provide a sputtering apparatus that provides high strength, high film formation rate, good controllability of magnetic field strength, and high quality film formation, and is particularly suitable for forming composite thin films of different materials.

[Means to solve the problem]

The above-mentioned object of the present invention is to provide a magnetic field generating means on the back side of a target disposed to face a substrate on which a thin film is formed, and a magnetron equipped with a cathode that generates a magnetic field substantially orthogonal to an electric field on the surface of the target. type sputtering apparatus, the target is composed of a plurality of divided parts and has an annular overall shape, and the magnetic field generating means has a plurality of individual structures corresponding to the divided parts of the target, This is accomplished by a sputtering apparatus characterized in that each of the electromagnets has at least an electromagnet whose magnetic force can be independently controlled, and the two poles of the magnetic field generating means are separated into an inner edge portion and an outer edge portion of the annular body. Can be done.

Embodiments of the present invention will be described in detail below.

FIG. 1 is a schematic view of the main parts of a sputtering apparatus according to this embodiment, and shows a cathode portion as a sectional view.

The sputtering apparatus shown in FIG. 1 is constructed entirely within a vacuum chamber 91, which can be evacuated to a desired pressure through an exhaust port 93 using a vacuum pump (not shown), and into which appropriate gas can be introduced through a gas inlet 92. It consists of a plurality of divided parts 130 so that the shape becomes an annular body, and the target (1, 2,
3, 4, 5, 6, 7, 8), and a rotatable holder 19 that removably holds a substrate 9, which is a member to be sputtered, so as to face the cathode 100. and is provided.

Each of the targets (1, . . . 8) is trapezoidal as shown in FIG. 2, and the overall shape is an octagonal annular body.
It has an appropriate inclination angle (α) so as to face the substrate 9).

Each target (1, 2, 3, 4, 5, 6, 7, 8)
are connected to eight separate target power supplies (only 10.20.70.80 is shown), and on the back side of each target (on the side opposite to the 7 node) there is a main magnet 2.
A magnetic field generating means is provided, which is an assembly of two permanent magnets 96 and 97 and an electromagnet, which is an auxiliary magnet, consisting of a soft magnetic yoke portion 95 and a solenoid coil 94. This magnetic field generating means includes the target (1,
...8) The permanent magnet 96 corresponding to the inner edge and the permanent magnet 97 corresponding to the outer edge are connected to the yoke part 95.
The solenoid coil 94 is wound around the yoke portion 95 as a core. A magnetic field (Xa) approximately perpendicular to the electric field generated between the 7 node side and the cathode side is generated near the surface of each target (1, . . . 8) by the permanent magnets 96, 97 and the solenoid coil 94. However, the structure is such that the strength of this magnetic field can be changed by controlling the excitation current of the solenoid coil 94. In this way, the magnetic field generating means has an N pole arranged over almost the entire outer edge part 97b of the target (1,...8) and an S pole arranged on the inner edge part 96a, so that the magnetic field generating means forms an annular shape along the target shape. A continuous closed magnetic field (Xa) is formed, and plasma can be trapped in a tunnel-shaped magnetic field that approximately corresponds to the overall shape of the target. Therefore, the erosion area substantially matches the overall shape of the target, uniformity of target consumption can be achieved, and the targets (1, . . . 8) can be used effectively. And each solenoid coil 94
, the strength of each magnetic field (Xa) of the eight divided parts 130 is controlled for each part by controlling eight independent electromagnetic power supplies (only 12 and 17 are shown) corresponding to each divided part 130. Can be controlled freely.

Further, the substrate 9 is located on the target center axis, and the inclination angle (α) of each target (1, . . . 8) is adjusted appropriately depending on the distance from the substrate 9. To prevent uneven incidence of particles scattered from each of the targets (1, . . . 8) on the substrate 9, and to prevent uneven film thickness, especially in composite film formation, as shown by the shaded area in FIG. For example, the target (1, 2, 3
, 4) and the other groups B (5, 6, 7, 8) are made of different metals such as transition metals and rare earth metals, the rotation of the substrate holder 19 greatly depends on the rotation of the substrate holder 19. The film quality and thickness can be stabilized without any problems.

The configuration for setting the inclination angle (α) of each target (1, . . . 8) includes a configuration in which the height (h) of the permanent magnets 96 and 97 is changed, or a configuration in which the inclination angle (α) is fixed. However, as shown in FIG. 1, the heights (h) of the permanent magnets 96 and 97 are the same, and the magnetic field generating means is attached to the bottom of the vacuum chamber 91 in an inclined manner, for example, by tightening with bolts. It is preferable that the inclination angle (α) can be adjusted for each divided portion 130 using a well-known structure such as the above. Note that if the gap between the magnetic poles in the adjacent divided portions 130 is increased, the continuity of the magnetic field (Xa) will deteriorate, so this gap varies somewhat depending on the magnetic field strength, etc., but is preferably about 3 mm or less.

The temperature of each of the targets (1, . . . 8) increases due to sputtering discharge, resulting in a decrease in sputtering efficiency.

For this purpose, although not shown, a well-known structure is provided in which cooling water flows under the target.

In order to cool or heat the substrate 9 depending on the characteristics of the deposited film, the substrate 9 is provided with a well-known structure or heater (not shown) through which cooling water flows on the back surface.

Major features other than those mentioned above of the sputtering apparatus of this embodiment described above will be described. Multiple pieces as mentioned above (8 pieces)
The divided sections 130 each have an independent magnetic field generating means. Therefore, in the sputtering film formation process using magnetron discharge, as a method for controlling the film formation rate and, in the case of composite materials, the composition,
A method of controlling the electric power applied to each target (1, . . . 8) and controlling the magnetic field xa, which is a leakage magnetic field on the target surface, by varying the excitation current of the solenoid coil of each of the dividing sections 130. By doing so, there are methods that use either one of the methods of increasing or decreasing the plasma density, or a method that combines both methods, and the control range can be made far wider than in the past. Among these methods, if the magnetic field control method is mainly used, which does not increase the load on the power supply device, the magnetic field strength of each of the divided sections 130 is independently controlled.
The evaporation rate of each target (1, . . . 8) from the target can be independently controlled. For example, if the annular target shown in Fig. 2 is divided into 8 parts and numbered in order counterclockwise, 1 of
．． 2.3.4 materials in group A, 5.6.7.8 materials in 8
When configured as a set, the current value of each of the solenoid coils 94 is set to the same condition for each set of materials, and the rotating shaft 19a of the holder 19 is set above the target so that its center axis coincides with the target center axis. Film formation is performed while rotating around the center. As a result, a high-quality mixed film (composite film) of materials A and B can be uniformly created with a desired composition. The composition ratio can be controlled by changing the number of combinations of the materials A%B or by increasing the magnetic field (xa).
This can be done very easily by changing the strength of the film, and since the conventional film thickness distribution correction plate shown in FIG. 8 and the like is not used, a thin film of any composition can be formed at high speed without wasting sputtered particles.

In addition, since each of the divided portions 130 is small, it is easy to obtain amperage to strengthen the magnetic field (xa), and the magnetic field strength can be made stronger than before. It is also extremely effective that it can be achieved at low cost. Moreover, the target (1
, . . . 8) and the erosion region caused by the magnetic field Xa almost match and are continuous, so that the distribution of the erosion region has no uneven scattering of sputtered particles with respect to the substrate 9. That is, the sputtering yield can be increased compared to conventional targets in which a plurality of targets are arranged, each of which forms a separate erosion region. As a result, even if the distance between the substrate 9 and the targets (1, . . . 8) is smaller than before, unevenness in film thickness distribution can be suppressed, and there is no waste of target material, making it extremely economical. .

Furthermore, especially when the substrate 9 is located approximately on the target center axis, the inclination angle (α) allows the flying of sputtered particles to the substrate 9 to vary in distance and direction from the circumferential direction to the entire substrate area. Since it is stable, a uniform film thickness can be obtained even in a configuration in which the substrate 9 does not rotate.

In the embodiment described above, the number of divided portions 130 is eight, but in the present invention, the number may be at least eight. or,
It goes without saying that the overall shape of the target is not a polygonal annular body, but may be annular as shown in FIG. In the case of an annular target, the magnetic field generating means includes permanent magnets 96 and 97, a yoke part 95, and the like shown in FIG.
It is composed of a solenoid coil 94, and as shown in FIG. 5, the shape of the permanent magnets 96 and 97 constituting the magnetic poles is preferably an arc shape corresponding to the target shape. Also, for example, as shown in FIG. 4, the material of the target material is A.

Of course, it is possible to easily form three types of mixed films by dividing into groups B and 03, or to form a mixed film of more than three types.

In the embodiment, the substrate 9 is connected to the canard 1.
00, and each target (1, . . . 8) was set at a desired inclination angle (α). However, the present invention is not limited to this, and the inclination angle (α) of the annular target may be set to zero, and the substrate 9 may have a revolution radius corresponding to the size of the target. In this case, when the substrate 9 revolves, the substrate 9 is placed under the same conditions with a high sputtering yield at any position, so that high-speed film formation can be performed and a good film thickness distribution can be obtained. In addition, when the said inclined j angle (α) is zero, it is also possible to use a ring-shaped target made of a single material or a mixture of materials.

In the device of the present invention, the combination of an electromagnet and a permanent magnet as in the embodiment described above includes a permanent magnet as the main magnetic field generating means,
The adjustment magnetic field generating means is not limited to electromagnets.
The main magnetic field generating means may be an electromagnet, and the adjustment magnetic field generating means may be a permanent magnet, or the structure may include only electromagnets.

〔Effect of the invention〕

As described above, in the sputtering apparatus of the present invention, the target provided in the cathode is composed of a plurality of divided parts, and its overall shape is an annular body, and the magnetic field generating means on the back side of the target is formed by dividing the target into two parts. a plurality of individual configurations corresponding to the respective parts, each having at least an electromagnet whose magnetic force can be independently controlled, and configured such that both poles of the magnetic field generating means are separated into an inner edge portion and an outer edge portion of the annular body. Therefore, even if the overall size of the cathode is large, it is easy to obtain amperage, and it is possible to obtain a large magnetic field strength and increase the deposition rate. By being able to independently control the sputtering, the control range of sputtering can be wider than before, and controllability during film formation can be improved and high-quality films can be obtained.Especially when forming mixed thin films of different materials, The composition ratio can also be easily controlled and the reproducibility of the film composition can be improved.

Furthermore, the cathode according to the present invention can have a denser distribution of erosion regions than a conventional target in which a plurality of targets are arranged, each forming a separate erosion region, and the scattering of sputtered particles can be reduced. Since the sputtering yield can be increased, the unevenness of the film thickness distribution can be suppressed even if the distance between the substrate and the target is smaller than before. Can be done. Furthermore, since it is possible to form an erosion region that substantially matches the overall shape of the target, the target material can be used effectively. Furthermore, by appropriately tilting the target surface toward the substrate positioned on the target center axis, the film thickness distribution can be made more uniform without relying on the complicated structure of conventional planetary jigs. can do.

Hereinafter, the effects of the present invention can be further clarified through Examples.

(Example 1) In the sputtering apparatus shown in FIG. 1, a device in which the overall shape of the cathode was annular was used. The number of divisions is 6,
The inner diameter of the cathode is 120mmφ, the outer diameter is 200mmφ,
(The inner and outer diameters of the cathode are approximately the same as the inner and outer diameters of the target.) The material of the target is titanium (Ti) with a purity of 4N.
, the thickness was 5 mm, and the inclination angle α was 30'.

The ampere frequency (AT) of the solenoid coil of each divided portion was set to 1500 to 2500 AT.

The substrate is made of circular glass material and its diameter is 12Qmmφ
And so.

Distance (L) between substrate and target is 70mm, 110m
A test was conducted for the case of 150 mm.

Other sputtering conditions are that the ultimate vacuum level is 1,0×1O-
6 Torr, sputtering gas is Ar, gas pressure is 2.0×1
The sputtering power applied to the target was O-3 Torr and 600 W. Film formation time: 10 minutes.

Table 1 shows test results regarding film thickness distribution and film formation rate.

Table 1 (Comparative Example-1) In an apparatus having a planetary jig as shown in Fig. 6, a disk-shaped target with an outer diameter of 200 mmφ was used, and the material of the target was titanium (Ti), purity 4N, and thickness 5.
mm, and a permanent magnet was used.

The distance between the substrate and target is 300 mm, 400 mm.
mm.

A test was conducted for a distance of 500 m. When sputtering was performed under almost the same conditions except for the above, the results shown in Table 2 were obtained.

Table 2 As is clear from Table 1 of Examples and Table 2 of Comparative Examples,
It can be seen that the sputtering apparatus of the present invention has an excellent film thickness distribution even when the distance between the substrate and the target is small, and also has an excellent film formation rate.

(Example 2) In the sputtering apparatus shown in FIG. 1, the overall cathode shape was also polygonal as shown in FIG. 2, and the number of divided parts was eight. The inner diameter of the cathode is 100mmφ, and the outer diameter is 180mmφ.
The target material of group A of target 1.2.3.4 is molybdenum (Mo) with a purity of 4N and a thickness of 3 m.
The target material for the eight sets of targets 5.6.7° and 8 was made of silicon (Si) with a purity of 5N and a thickness of 3 mm, and the inclination angle α was 300.

A circular silicon wafer is used as the substrate, and its diameter is φ4.
”.

The distance (L) between the substrate and the target was 60 to 12 Qmm, and the amperage for each group A and 8 groups was as shown in Table 3.

Other sputtering conditions are that the ultimate vacuum level is 6.0 x 10-
Torr, sputtering gas is Ar, gas pressure is 2.0x1
The sputtering power applied to the target was 0-3 Torr, 600 W for each divided portion of group A, 400 W for each divided portion of group B.

Table 3 shows test results regarding film thickness distribution and film composition ratio.

Table 3 As shown in Table 3, according to this example, the composition ratio of the film can be freely changed by simply changing the amperage (AT) of the eight sets, and a good film thickness distribution can be maintained. is possible,
Moreover, the distance between the substrate and the target is 60nwn compared to about 400nwn in a conventional device using a planetary jig.
It was possible to make it extremely small, 120 mm.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a sputtering apparatus that is an embodiment of the present invention, FIG. 2 is a plan view of the target shown in FIG. 1,
3 is a perspective view of the main part of the divided part, FIG. 10 is a plan view showing the shape of another target in the present invention, and FIG. 5 is a perspective view of the main part of the divided part corresponding to the shape of the target shown in FIG. 4. figure,
6 to 8 are schematic diagrams of conventional sputtering equipment,
FIG. 9 is a schematic cross-sectional view of a cathode portion in a conventional sputtering apparatus, and FIG. 10 is a plan view showing an erosion area in the target shown in FIG. 9. 1.2.3.4.5.6.7.8...Target,
9... Board, 10.20.70.80... Target power supply, 12.17... Electromagnet power supply, 1
9... Substrate holder, 19a... Rotating shaft, 91
...Vacuum chamber 92...Gas inlet, 93
・・Exhaust port, 94・・Solenoid coil,
95...Yoke part, 96.97...Permanent magnet 96a...
Inner edge, 97b... Outer edge, 100... Cathode, 130... Divided part. Figure Sea Figure Figure Figure

Claims (1)

[Claims] In a magnetron type sputtering apparatus, a magnetron-type sputtering apparatus is provided with a magnetic field generating means on the back side of a target disposed to face a substrate on which a thin film is formed, and is equipped with a cathode that generates a magnetic field substantially perpendicular to an electric field on the surface of the target. The target is composed of a plurality of divided parts and has an annular overall shape, and the magnetic field generating means has a plurality of separate structures corresponding to the divided parts of the target, and each has independent control of magnetic force. 1. A sputtering apparatus characterized in that the sputtering apparatus has at least an electromagnet and is configured such that both poles of the magnetic field generating means are separated into an inner edge portion and an outer edge portion of the annular body.