JPH034620B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a film forming method using planar magnetron sputtering, which aims to extend the life of a target flat plate used in a thin film material sputtering device and to control the deposited film thickness distribution on the sample surface. This is related to the device.

Sputtering technology ionizes (plasma-like) low-pressure atmospheric gas by causing glow discharge.
A high voltage applied between the anode and cathode electrodes accelerates the plasma-like ions and causes them to collide with a plate of target material placed at the cathode.

This is a technique in which the constituent atoms or particles of the target material ejected by the collided ions are deposited on a substrate provided near the anode to form a thin film of the target material.

In this case, it is important to confine the ions generated by the glow discharge in a space with a high density and carry them effectively onto the target material plate in order to improve the deposition rate and reduce damage to the substrate caused by electrons. It is becoming.

For this purpose, it is effective to confine the ions to a spatial region on the flat surface of the target material and increase the density. The magnetic field configuration has also been studied.

In particular, planar magnetron sputtering equipment has come to have a deposition rate comparable to conventional resistance heating vacuum evaporation equipment, and has recently been used as a thin film forming equipment for thin film integrated circuits and semiconductor devices in the production process. It came to be used frequently.

FIG. 1 is a conceptual cross-sectional view showing the structure of a planar magnetron type sputtering apparatus in the vicinity of a flat plate of target material according to the well-known prior art. A ring-shaped magnetic pole 2 magnetically coupled to the back surface of a target material flat plate (hereinafter referred to as target flat plate) 1 by a yoke 6, and a cylindrical magnet 3 at the center of the ring-shaped magnetic pole 2 are arranged to constitute a magnetic circuit. ing. These magnetic poles 2 and 3 create a distribution of magnetic lines of force in the space on the surface side of the target 1 (lower side of Fig. 1), in other words, the torus is divided in half on a plane perpendicular to the height direction. However, a semicircular magnetic field distribution, commonly called a tunnel-shaped magnetic field distribution 11, whose half-cut plane is parallel to the surface of the target flat plate 1 is generated. This tunnel-like magnetic field distribution 11 confines the plasma-like ions in a high concentration therein (not shown). These plasma ions are further exposed to an electric field almost perpendicular to the surface of the target flat plate 1 generated by a high voltage applied between the anode 10 and the cathode 7 installed on the back surface of the target flat plate 1 via an insulating spacer 8. As a result, the atoms or particles are accelerated and collide with the surface of the target flat plate 1, and as a result, the atoms or particles are sequentially ejected from the surface of the target 1, forming an eroded region 12.

Note that 5 is a water cooling mechanism. This erosion area 12
As estimated from the above explanation, the degree of erosion increases as time passes in the sputtering process, but
In the target flat plate structure shown in FIG. 1, this erosion usually progresses only in a specific area of the target flat plate, so that it is said that only the volume of the eroded area can be effectively used.

Therefore, even if the desired uniform film thickness distribution is initially obtained, the formation of such erosion regions changes the direction and amount of the atoms of the target material that are ejected.
The film thickness distribution of the thin film to be deposited on the surface of the sample substrate changes over time, and the variation in the allowable film thickness distribution becomes large. There is a drawback that the lifetime of the target material is determined by deterioration over time.

For this reason, when it is desired to continuously form films on a large number of sample substrates or to perform a long sputtering process, it becomes impossible to do so, and this has been considered a limitation of the conventional sputtering process. After that, in order to remove this defect, the erosion area 1 is
It has been proposed to change the magnetic field distribution 11 so that the magnetic field 2 is generated over a wide area on the surface of the target flat plate 1 (Japanese Patent Laid-Open Nos. 51-86083 and 1982-7586).

The theoretical background and technical idea of this technology are described in JP-A No. 51-86083, page 2, lower right column, 19th page.
As stated in the 2nd line of the 3rd page, top left column, ``The greatest target erosion occurs when the magnetic field lines align with and lie below the above point or area where the magnetic field lines are parallel to the target plate. It is said that "occurs in areas where
No. 86183, as stated in claim 1, generates an auxiliary variable magnetic field in the direction perpendicular to the source for the first magnetic field means, 4 of the drawings as a specific technique.
An embodiment in which the electromagnets shown in the figure are arranged in an upright manner is disclosed. On the other hand, in Japanese Patent Application Laid-Open No. 53-7586, the technique is simply to mechanically move the magnet means itself.

However, the inventors reconsidered the technical ideas in the above-mentioned known examples in light of the experimental facts of the inventors, and found that the effects are even more effective than the technical means shown in the above-mentioned known examples. In addition, we were able to realize a new technology that allows almost arbitrary control of the thickness and distribution of the deposited thin film.

An object of the present invention is to solve the problems of the prior art described above, by using a planar magnetron sputtering method that can be easily and practically controlled so that a uniform film thickness distribution can be obtained on a substrate on which a film is to be deposited. An object of the present invention is to provide a film forming method and an apparatus thereof.

That is, in order to achieve the above object, the present invention has the following features:
When magnetic flux lines are generated from a single magnetic flux source, the magnetic fluxes do not intersect with each other, and an attractive or repulsive force called Maxwell stress acts on each other. 1 magnetic pole body and a ring-shaped second pole body installed around it.
A magnetic pole body and a third magnetic pole body provided around it are arranged, a target is installed at the tips of these magnetic pole bodies, and the rear ends of these magnetic pole bodies are attached to a plate-shaped body formed of a magnetic material. At least two magnetic pole bodies, at least one of which is an electromagnet, are connected magnetically to the three magnetic pole bodies in order to generate an annular tunnel-shaped main magnetic flux that confines the prism ring on the target and move the annular plasma generation region. Using a planar magnetron type sputtering electrode equipped with a magnetic field generating means, the time interval of the periodic current waveform applied to the electromagnet is controlled by the electromagnet control means, so that the residence time in the large annular plasma generation region is changed to the small annular plasma generation region. A uniform film is formed by making the residence time longer than the residence time in the plasma generation region, moving the annular plasma generation region at least once or more, and combining the film thicknesses obtained in each annular plasma generation region obtained according to the time interval. This is a film forming method using sputtering. Further, the present invention provides a first magnetic pole body provided at the center of the target, an annular second magnetic pole body provided around the first magnetic pole body, and a third magnetic pole body provided around the first magnetic pole body. , targets are installed at the tips of these magnetic pole bodies, and the rear ends of these magnetic pole bodies are magnetically connected to a plate-shaped body formed of a magnetic material, and an annular tunnel-shaped main magnetic flux confines the plasma ring above the target. A planar magnetron type sputtering electrode equipped with at least two magnetic field generating means, at least one of which is an electromagnet, is provided on each of the three magnetic pole bodies in order to generate and move an annular plasma generating region. The time interval of the current waveform is controlled to make the residence time in the large annular plasma generation region longer than the residence time in the small annular plasma generation region, and the annular plasma generation region is moved at least once to increase the time. This is a sputtering film forming apparatus characterized by being provided with an electromagnetic control means that synthesizes the film thicknesses of the respective annular plasma generation regions obtained according to the intervals and forms a uniform film. The present invention also provides an electromagnet control means for the sputtering film forming apparatus, including a digital control signal generating means for generating a digital control signal, and a digital control signal generating means for controlling the electromagnet based on the digital control signal generated by the digital control signal generating means. This is a film forming apparatus using sputtering, characterized by having current amplification means for controlling the time interval of the applied current waveform.

The present invention will be specifically described below based on embodiments shown in the drawings.

FIGS. 2 and 3 are schematic cross-sectional views of an embodiment of an electrode portion of a sputter electrode structure according to the present invention. The main component of the electrode part is a target flat plate 21 (254 mmφ, 20 mm thick).
A backing plate 22 (made of copper), which serves as a cathode, is placed in a predetermined hollow space on the first main surface of the target flat plate 21. a magnetic field generating yoke 23, which is a means for generating a magnetic flux distribution;
inner electromagnetic coil 24, outer electromagnetic coil 25,
Center pole tip 26, inner pole tip 27, outer pole tip 2
8, a shield 30 serving as an anode, and an insulating spacer 31.

In the embodiment shown in FIG. 2 and FIG. 3, the target flat plate 21 is circular, but this is because the substrate on which the film is to be formed used in this embodiment is circular, and when a rectangular substrate is used, a rectangular target is used. It would be appropriate to prepare a flat plate. That is, the circular electrode structure electrode portion described in this example is one example,
The shape of the electrode portion, such as a rectangle, does not deviate from the scope of the present invention.

Further, a flow path 32 for passing a coolant such as water is formed on the back side of the packing plate 22, and a pipe is provided in this flow path 32 for supplying and discharging the coolant from the outside via a magnetic field generating yoke 23. 21 to be cooled.

FIG. 4 shows a schematic configuration of the excitation power source for this electrode structure. The main configuration of the excitation power supply section includes two current supply circuits for controlling the inner electromagnetic coil 24 and the outer electromagnetic coil 25 completely separately. The current applied to the excitation power source and the inner and outer electromagnetic coils 24 and 25 can be applied completely arbitrarily, that is, a constant current that does not change over time, or a current waveform such as a rectangular waveform or a triangular waveform with a constant period. It uses a microprocessor 41 and a memory 42 so as to be able to set a predetermined current waveform, and provides information regarding a predetermined current waveform from a keyboard 43 or a suitable external storage device 40 (e.g. magnetic tape, magnetic disk). Digital output of microprocessor 41
In addition to analog signal converters 44a and 44b (D-A converters), a current amplifier 45
a, 45b, the inner and outer electromagnetic coils 24, 2
5 is amplified to a predetermined intensity sufficient to excite the magnet.

The excitation power supply unit shown in FIG. 4 has the following objects to be controlled:
Since we are dealing with the inner and outer electromagnetic coils 24 and 25,
The power supply has constant current characteristics, and the output current detection units 46a and 46b detect the output current, that is, the current value of each electromagnet, and the output current is detected by the D/A converter 44.
a, 44b are compared with a predetermined current value output,
In order to perform correction, it has means for feeding back information to the current amplifiers 45a and 45b. That is, it is configured such that a constant current or a constant rectangular wave current is applied to the electromagnetic coils 24 and 25.

As is well known, a high-voltage power supply for supplying the discharge force for sputtering, that is, a sputtering power supply, has an output voltage of about 0 to 800V and an output current of about 0 to 15A. there was. Furthermore, as is well known, this high voltage power supply has constant current output characteristics in order to control the power input to the glow discharge.

As mentioned above, the eroded region where sputtering occurs on the target plate is located almost directly below the location where the plasma ring is generated. In addition, the generation of plasma rings occurs within 10 to 20 mm from the first main surface of the target flat plate between the hollow spaces on the first main surface of the target flat plate under a sputtering pressure of 1 to 10 mTorr used in a normal planar magnetron. The magnetic field vectors at a distance of about 100 mm are focused in a region parallel to the first major surface of the target plate.

Therefore, in order to know the location where the erosion region occurs on the target flat plate, it is effective to know the magnetic flux distribution in the hollow space on the first main surface side of the target flat plate.

Therefore, before conducting experiments to determine various characteristics such as the film thickness distribution of the sputtered electrode structure according to this embodiment, the magnetic flux distribution in the hollow space 29 on the first main surface of the target flat plate 21 should be evaluated. It was measured. A Gauss meter was used to measure the magnetic flux distribution.

5 and 6 are almost the same as the present embodiment shown in FIG. This is an example of a yoke material manufactured and measured. The difference between the embodiment shown in Fig. 2 and this pseudo-manufactured yoke is as shown in Fig. 2.
The groove in which the outer electromagnetic coils 24 and 25 are embedded is shallow. The vertical axis of Figures 5 and 6 is
The height (mm) above the magnetic pole tips 26, 27, 28, the horizontal axis is the central axis of the sputter electrode part of the sputter electrode structure shown in FIG. The distance to (mm). Fifth
In the figures and FIG. 6, the directions of the currents flowing through the inner coil 24 and the outer coil 25 are opposite to each other. In FIG. 5, the magnetomotive forces of the inner electromagnetic coil 24 and the outer electromagnetic coil 25 are set to be 40:1, respectively. In FIG. 6, the magnetomotive force of the inner electromagnetic coil 24 and the outer electromagnetic coil 25 is 1.5:
I set it to 1.

As mentioned above, since the plasma ring occurs in the region where the magnetic field vector is parallel to the first main surface of the target flat plate 21, the plasma ring is generated in the regions indicated by 53 and 54 in FIGS. 5 and 6, respectively. occurs.

Therefore, as is clear from FIGS. 5 and 6, by changing the magnetomotive force that energizes the inner and outer electromagnetic coils 24 and 25, the location where the plasma ring is generated can be moved.

In the example shown in FIGS. 5 and 6, the magnetomotive force of the inner electromagnetic coil 24 is constant, and the magnetomotive force of the outer electromagnetic coil 25 is reduced from 1/40 to 1/1.5 of the magnetomotive force of the inner electromagnetic coil 24. However, conversely, even if the magnetomotive force applied to the outer electromagnet coil 25 is kept constant and the magnetomotive force applied to the inner electromagnet coil 24 is changed, the magnetic field vector will not change to the target as in FIGS. 5 and 6. A region parallel to the flat plate 21 can be moved.

Next, the thickness distribution characteristics of each film formed in this example will be described. Figure 7 shows a structure placed parallel to the first main surface of the target flat plate at a distance of 85 mm from the first main surface of the target flat plate, with respect to the diameter D of the annular erosion area generated on the target flat plate. Film target substrate 2
How the thickness distribution characteristics of the deposited film on 0 change,
This is an example obtained by calculation, and explains the first basic technical idea of the present invention. The vertical axis shows the film thickness with the film thickness at the center of the target substrate as 100%, and the horizontal axis shows the outward radius from the center of the target substrate on the target substrate. The distance in the direction (mm) is indicated.

As is clear from FIG. 7, if the diameter D of the annular eroded region is downward, the radius
The thickness distribution characteristic of the deposited film has a shoulder at about 100 mm, which has a so-called bimodal shape. On the other hand, when D=125 mm or less, this shoulder in the film thickness distribution characteristic disappears, and a so-called unimodal film thickness distribution characteristic with a peak at the center on the substrate to be formed is obtained.

The above discussion was about the diameter D of the annular eroded region, but as mentioned earlier, this eroded region occurs almost directly under the plasma ring, so the diameter of the annular eroded region is the same as the diameter of the plasma ring. I can't help but think about it. Therefore, the fifth
With the controllability of the magnetic field distribution characteristics shown in Fig. 6 and Fig. 6, it is expected that by changing the diameter of the plasma ring, it will be possible to arbitrarily obtain various film thickness distribution characteristics as shown in Fig. 7. .

A curve 61 shown in FIG. 8, for example, allows the current in the inner electromagnetic coil 24 and the current in the outer electromagnetic coil 25 shown in FIG. , is a conceptual diagram of the film thickness distribution characteristics expected to be obtained when the ratio with the inner electromagnetic coil 24 is 1:40, and the curve 62 shown in FIG. , is a conceptual diagram of the film thickness distribution characteristics obtained when the diameter of the plasma ring is reduced by setting the ratio of magnetomotive force to the outer electromagnetic coil 25 to 1.5:1.

During the film formation process on one film formation target substrate,
If the magnetomotive force of the outer electromagnet is changed and an operation is performed to give the film thickness distribution as shown in curves 61 and 62 shown in FIG. A uniform film thickness can be obtained over a wide range on the substrate to be film-formed, as shown by a curve 63 shown in FIG.

FIG. 9 shows an example of the film thickness distribution characteristic in this embodiment, and a curve 71 shows a magnetic field of about 200 Gauss generated by the inner electromagnetic coil 24, with the magnetomotive force of the outer electromagnetic coil 25 being 0. strength,
This is what happens when you make it available on the target. Further, song 71 shows the film thickness distribution characteristics when the ratio of the magnetomotive force between the inner electromagnetic coil 24 and the outer electromagnetic coil 25 is set to 5:1. 9th
Curves 71 and 72 in the figure indicate a distance of 80 mm from the first main surface of the target flat plate 21 to the substrate to be film-formed.
Argon gas with a purity of 99.999% was used as the sputter gas, and the sputter gas pressure was 5.4 wTorr.

The vertical axis in FIG. 9 shows the film formation speed on the substrate to be film-formed, and the horizontal axis shows the direction radially outward from the central axis of the electrode portion of the sputter electrode structure of this example. Distance on the substrate to be filmed (mm)
It is.

As is clear from FIG. 9, by increasing the magnetomotive force applied to the outer electromagnetic coil 25 and relatively reducing the difference between it and the magnetomotive force applied to the inner electromagnetic coil 24, the diameter of the plasma ring becomes smaller. A film thickness distribution characteristic as shown by the curve 62 in FIG. 8 can be obtained, and conversely, by reducing the magnetomotive force applied to the outer electromagnetic coil 25, the diameter of the plasma ring becomes large. A film thickness distribution characteristic as shown by the curve 61 is obtained.

Although the plasma ring moves even if the magnetomotive force of the outer electromagnetic coil 25 is changed to obtain the film thickness distribution 71 and 72 in FIG. There is no change of more than ±5% in ``voltage'' ÷ ``current flowing to the target.'' As mentioned above, in this example, a sputter power supply with constant current output characteristics is used. The generated sputter power hardly changes.

For this purpose, under the conditions of this embodiment in which a constant sputtering power is applied, when the diameter of the plasma ring is made small, the area of the plasma ring, that is, the first main surface on the target flat plate, is eroded by sputtering. Since the area of the region receiving the irradiation becomes smaller, the power per unit area on the first main surface of the target flat plate 21 increases. As is well known, in planar magnetron sputtering, the deposition rate on the substrate to be deposited is approximately proportional to the power per unit area applied to the eroded region on the target flat plate. Therefore, when the plasma ring diameter is small, the deposition rate in the central region of the substrate to be deposited is 9 times faster than when the plasma ring diameter is large.
As shown in the figure, it is large.

In order to synthesize the monomodal and bimodal film thickness distribution characteristics shown in Figure 8 and obtain a film thickness distribution as uniform as possible over a wide area, it is necessary to During the film process, it is necessary to carefully select the ratio between the time when the plasma ring diameter is made small and the time when the plasma ring diameter is made large. As mentioned above, when the plasma ring diameter is small, the film formation rate at the center is higher than when the plasma ring diameter is large. The optimum film thickness distribution characteristics cannot be obtained on the target substrate unless the ratio of "the time during which the film is increased" is set to 1 or less.

Furthermore, it is thought that the amount of erosion in the area subject to erosion, that is, the progression of erosion in the thickness direction of the target plate, is proportional to the amount of sputtering power input per unit area onto the target plate. It is preferable that the amount of erosion in the area on the target plate corresponding to the position where the plasma ring diameter is small is equal to the amount of erosion in the area on the target plate corresponding to the position where the plasma ring diameter is large. This is because if the amount of erosion is unbalanced, the erosion depth in one of the eroded areas will reach the thickness of the target plate first, and the life of the target plate will be longer than 100% if the erosion progresses uniformly in both eroded areas. compared,
It can be said that the life of the target plate is short.

FIG. 10 shows a typical composite film thickness distribution characteristic obtained by actually forming a film and synthesizing the film thickness distribution characteristics shown by curves 71 and 72 in FIG. 9. Curves 71 and 72 in Figure 9 are calculated and synthesized to allow a film thickness deviation of ±5% and obtain a uniform film thickness over the widest area. A film was formed by selecting a material that would take a long time for a small ring diameter. The circle mark in Fig. 10 is based on the thickness distribution characteristics of the deposited films shown in Fig. 9.
This is a plot obtained by calculation, and the solid line 81 is
These are actual measurements taken during actual film formation, and show very good agreement.

The film forming conditions indicated by the curve 81 in FIG. 10 are the same as those for determining the film thickness distribution characteristics shown in FIG. 9. Furthermore, the excitation conditions for the inner and outer electromagnetic coils are such that the magnetomotive force of the inner electromagnetic coil 24 is constant via the D/A converter 44a and the current amplifier 45a according to a command from the MPU 41, and the magnetomotive force of the outer electromagnetic coil is
As shown in FIG. 11, the command from the MPU 41 causes
The time T ₁ is 10 seconds when the plasma ring diameter is at its maximum due to the rectangular waveform pulse current, and the time T ₂ is when the plasma ring diameter is the minimum at 2000 ampere turn.
is 2 seconds, the period T ₀ is 12 seconds, and 10
I was able to repeat it several times.

Note that the time T ₁ may be zero current or negative current.

As described above with the experimental results, the film thicknesses described in Figs. The first basic technical idea of the present invention, which is to synthesize distributions, is that under the condition that the input sputtering power is constant, the ratio of "time when the plasma ring diameter is small" ÷ "time when the plasma ring diameter is large" is 1. The purpose is to change the magnitude of each of the inner and outer electromagnet currents so that the ratio of the above times is less than 1, and conversely, the utilization efficiency or lifespan of the target plate is determined by the excitation method of each electromagnet such that the above-mentioned time ratio is less than 1. There are conditions under which it is possible to obtain a flat film thickness distribution while improving the film thickness distribution.

In the prior art planar magnetron electrode with a fixed magnetic field, as local erosion of the target plate progresses, a valley is formed in the cross section of the target plate with a steep V-shape.
It has already been mentioned that as the V-shaped valley formation progresses, the film thickness distribution deteriorates. To explain this more specifically, when the consumption time of the target flat plate is short, as is well known, the manner in which the target flat plate material is scattered by sputtering is distributed according to the cosine law as shown in Fig. 12b. The curve 101) shows that the particles sputtered over a relatively wide solid angle are scattered.

On the other hand, as the aforementioned V-shaped valley is formed on the target flat plate, the scattering direction distribution shown in FIG. 12b becomes narrower as shown by the curve 111 in FIG. 13b. . curve 101
The outline of the film thickness distribution corresponding to the curve 111 is shown by the curves 102 and 112 in FIGS. 12a and 13a.
As shown in FIG. 2, due to the formation of the V-shaped valley, the thickness distribution of the deposited films becomes uneven, and the thickness distribution of the deposited films deteriorates.

FIG. 14 shows the change over time in the film thickness distribution when the magnetomotive forces of the inner and outer electromagnetic coils shown in FIGS. 2 and 3 are the same. Curve 121 is a constant power of 6kw1, and after 0 hours of use,
122 is the film thickness distribution characteristic after use for 10 hours, 123 is for 20 hours, and 124 is after 30 hours of use. Also curve 1
The maximum erosion depth at points 21, 122, 123, and 124, that is, the depth of the bottom of the V-shaped valley, is 0, respectively.
They were 2, 4, and 6 mm.

As is clear from Figure 14, the maximum erosion depth is 6.
mm, the film thickness distribution characteristic exceeds the practical range of ±5% (+10% in curve 123 in FIG. 12) for a substrate with a diameter of 150 mm.

FIG. 15 shows the second basic idea of the present invention and the most remarkable effect.

Figure 15 shows the conditions for obtaining the composite film thickness distribution shown in Figure 10, that is, the thickness distribution characteristics of each film when film formation is continued while decreasing or increasing the plasma ring diameter at a ratio of 1:5. This shows the change over time, and as in Fig. 14, the sputtering power of 6 kW was kept constant. Curve 131 is the film thickness distribution characteristic when the target plate is consumed for 0 hours, curve 132 for 20 hours, curve 133 for 40 hours, and curve 134 for 60 hours.

Comparing Figures 14 and 15, it is clear that if the eroded area of the target plate is expanded by periodically changing the size of the plasma ring, the V-shaped valley can be formed. This means that due to the delay or the large apex angle of the V-shaped valley, changes over time in the thickness distribution of the deposited films occur to an extent that is hardly a problem in practice.

The above can also be confirmed from FIG. 16. FIG. 16 shows the actual measurement of the cross-sectional shape of the eroded area of the target flat plate 21 when the target was exhausted for 30 hours under the conditions shown in FIGS. 14 and 15. Curve 141 corresponds to the condition shown in FIG. 14, that is, when the size of the plasma ring is constant, and curve 142 corresponds to the condition shown in FIG. 15, that is, when the size of the plasma ring is changed periodically. be. It can be confirmed that the V-shaped valley of the curve 141 has a narrower apex angle than the curve 142, and a larger shoulder appears in the film thickness distribution characteristic.

The embodiment shown in FIG. 2 has been described above, but as shown in FIG. 10, the film was formed on a substrate of about 150 mm in diameter. However, the present invention can also be applied to film formation on a larger area substrate. As can be seen from the curve 142 in FIG.
For a substrate with a size of about 150 mm, sufficient thickness distribution characteristics can be obtained even if the amplitude of the erosion area is not large. However, when forming a film on a substrate with a larger area using the sputter electrode according to the present invention, the size of the target flat plate 21 must be increased to match the size of the substrate.

In this case, the above-described simple method of controlling the generation location of the plasma ring to only two positions will not produce a continuous eroded area as shown by the curve 142 in FIG. 16. In other words, curve 1 in Figure 16
Since annular erosion areas such as 41 are formed on the target flat plate 21 in two separate locations, the material utilization efficiency of the target flat plate 21 is reduced. Therefore, by forming one or multiple eroded areas in the area between the double annular eroded areas, it is possible to improve the material utilization efficiency. In this case, an example of a current waveform that is converted into an analog signal by the D/A converter 44b in response to a digital command signal from the MPU 41 and applied to the outer electromagnetic coil 25 by the current amplifier 45b is shown in FIG. _The diameter of _the plasma ring is at its maximum at the time T ₁ ′ shown in FIG _.
It assumes an intermediate size and returns to its initial state. If T ₂ ′ is the time during which the plasma ring diameter is at the medium diameter, then T ₂ ′ = T ₂ ″ + T ₂ In order for the erosion area to be the same in the erosion area corresponding to each plasma ring diameter, and for the widest possible area of the target plate to be uniformly consumed, the condition T ₁ ′>T ₂ ′>T ₃ ′ is satisfied. is essential.

In both of the plasma ring diameter control methods shown in FIGS. 11 and 17, under the condition that the sputtering power is constant, the plasma ring diameter is maintained when the plasma ring diameter is larger. Keeping the plasma ring diameter longer than the time it takes to maintain a plasma ring diameter smaller than the plasma ring diameter is important in order to uniformly wear out the target plate over as wide an area as possible and to maintain a uniform coating on the substrate to be deposited. The basic technical idea of the present invention is to apply a thick film.

In the embodiment of FIG. 2 according to the present invention, in order to change the size of the plasma ring diameter, it is sufficient to change the relative strength of the magnetomotive force caused by the inner electromagnetic coil and the magnetomotive force caused by the outer electromagnetic coil. Also mentioned. Furthermore, regarding the ease of configuring the excitation power supply section of the electromagnet, it is advantageous to change the size of the plasma ring diameter by simply changing the current applied to the coil of either the outer or inner electromagnet. The control methods shown in FIGS. 11 and 17 have been explained by taking as an example the control of the current value applied to the outer electromagnetic coil 25.

Another embodiment of the present invention is the 18th embodiment.
As shown in the figure, a part or the whole of the central magnetic pole is replaced with a constant strength magnetic flux generating means, that is, a permanent magnet 2001 in FIG. 18, and an outer electromagnetic coil 25
If only the current applied to the plasma ring has a waveform as shown in FIGS. 11 to 17, it is possible to control the diameter of the plasma ring in the same manner as in the embodiment shown in FIG.

As yet another embodiment of the present invention, the nineteenth
As shown in the figure, the outer magnetic pole is connected to a magnetic flux generating means with a constant strength,
That is, in FIG. 19, the permanent magnet 2002 is partially or completely replaced, and the inner electromagnetic coil 2 is replaced with the permanent magnet 2002.
11 to 17.
If the waveform shown in the figure is used, it is possible to control the diameter of the plasma ring in the same way as in the embodiment shown in FIG. However, in the case of the embodiment shown in FIG. 19, if the current value applied to the inner electromagnetic coil 24 is made small, the plasma ring diameter becomes small.
Conversely, if the current value applied to the inner electromagnet coil 24 is increased, the diameter of the plasma ring becomes larger.

Therefore, in order to make the time when the plasma ring diameter is large, which is the main point of the present invention, longer than the time when the plasma ring diameter is small, for example, the inner electromagnet shown in FIG. Regarding the excitation current waveform of the coil 24, the condition T ₁ ′<T ₂ ′<T ₃ ′ is essential, contrary to the case of the outer electromagnetic coil.

As described above, according to the present invention, in planar magnetron sputtering with an annular double magnetic pole structure, the time interval of the periodic current waveform flowing through the electromagnet is controlled by the electromagnet control means. The annular plasma generation region can be made to oscillate at intervals, and as a result, a uniform deposited film thickness can be easily obtained on the substrate, which is advantageous for practical use.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a conventional planar magnetron sputter electrode, FIG. 2 is a cross-sectional view showing a planar magnetron sputter electrode according to the present invention, and FIG.
The figure is a perspective view of FIG. 2, FIG. 4 is a diagram showing the configuration of a drive device for driving the electromagnet shown in FIGS. 2 and 3, and FIGS. Figure 7 is a diagram showing an example of magnetic field measurement, Figure 7 is a diagram showing an example of calculation of changes in film thickness distribution characteristics, Figure 8 is a diagram conceptually showing synthesis of film thickness distribution characteristics,
FIG. 9 is a diagram showing film thickness distribution characteristics according to an embodiment of the present invention, FIG. 10 is a diagram showing an example of a composite film thickness distribution obtained by combining the film thickness distributions shown in FIG. 9, and FIG. Figures 12 and 13 show current waveforms when the magnetomotive force of the inner electromagnetic coil is kept constant and the magnetomotive force of the outer electromagnetic coil is periodically controlled in order to obtain the composite film thickness distribution shown in Fig. 10. The figure is a conceptual diagram explaining the change in the film thickness distribution characteristics as the target erosion progresses. Figure 14 is a conceptual diagram explaining the change in the film thickness distribution characteristics as the target erosion progresses. FIG. 15 is a diagram showing the change over time in the film thickness distribution characteristic of the deposited film. As in the present invention, the magnetomotive force of the inner electromagnetic coil is kept constant, and the outer electromagnetic coil is
Figure 16 is a diagram showing the state of wear of the target flat plate in an embodiment of the present invention, and Figure 17 is a diagram showing changes over time in the film thickness distribution characteristics when the periodic current waveform shown in the figure is applied. FIG. 18 is a diagram showing an example of the current control waveform applied to the outer electromagnetic coil in order to form a film on a larger-area film-forming target substrate. The figure shown in FIG. 19 is a diagram showing an embodiment in which the outer magnetic pole is replaced with a permanent magnet in the present invention. 20...Substrate to be film-formed, 21...Target flat plate, 22...Backing plate, 23...Yoke for magnetic field generation, 24...Inner electromagnetic coil, 25
...Outer electromagnetic coil, 41...Microprocessor, 42...Memory, 43...Keyboard, 4
4a, 44b...D/A converter, 45a, 45b
...Current amplifier, 46...Detection section.

Claims (1)

[Claims] 1. A first magnetic pole body provided at the center of a target, an annular second magnetic pole body provided around the first magnetic pole body, and a third magnetic pole body provided around the first magnetic pole body. A target is installed at the tips of these magnetic pole bodies, and the rear ends of these magnetic pole bodies are magnetically connected to a plate-shaped body formed of a magnetic material. In order to generate a main magnetic flux and move an annular plasma generation region, a planar magnetron type sputtering electrode having at least two magnetic field generating means, at least one of which is an electromagnet, is provided on the three magnetic pole bodies, and an electromagnetic control means is used. By controlling the time interval of the periodic current waveform flowing through the electromagnet, the residence time in the large annular plasma generation region is made longer than the residence time in the small annular plasma generation region, and the annular plasma generation region is
A film forming method using sputtering, characterized in that a uniform film is formed by combining the film thicknesses obtained in each annular plasma generation area according to time intervals by moving the film more than once. 2 A first magnetic pole body provided at the center of the target, an annular second magnetic pole body provided around the first magnetic pole body, and a third magnetic pole body provided around the first magnetic pole body, and these magnetic pole bodies A target is installed at the tip of the magnetic pole body, and the rear ends of these magnetic pole bodies are magnetically connected to a plate-shaped body formed of a magnetic material, which generates an annular tunnel-shaped main magnetic flux that confines the plasma ring above the target. In order to move the annular plasma generation region, a planar magnetron type sputtering electrode equipped with at least two magnetic field generating means, at least one of which is an electromagnet, is provided on the three magnetic pole bodies, and the periodic current waveform flowing through the electromagnet is The time interval is controlled so that the stay time in the large annular plasma generation area is longer than the stay time in the small annular plasma generation area, and the annular plasma generation area is moved at least once or more according to the time interval. A film forming apparatus using sputtering, characterized in that an electromagnetic control means is provided for synthesizing the film thicknesses of the resulting annular plasma generation regions to form a uniform film. 3. The electromagnet control means controls a time interval of a current waveform applied to the electromagnet based on a digital control signal generation means for generating a digital control signal and a digital control signal generated by the digital control signal generation means. 3. A film forming apparatus by sputtering according to claim 2, further comprising current amplification means. 4. A film forming apparatus by sputtering according to claim 2, wherein the electromagnet is installed between the second magnetic pole body and the third magnetic pole body.