JPH02107764A - Magnetron sputtering equipment - Google Patents

Abstract

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

Description

Detailed Description of the Invention (Industrial Application Minute Hand) This invention aims to extend the service life of the ferromagnetic target material by suppressing the occurrence of local erosion. This invention relates to a magnetron sputtering device that maintains the magnetic field distribution near the top surface of a material almost constant, so that changes over time in film-forming conditions can be almost ignored.

[Conventional technology]

A conventional magnetron sputtering apparatus will be explained with reference to FIG. In this figure, reference numeral 1 denotes a target material made of ferromagnetic material, on the back surface of which are arranged an inner magnetic pole 2 and an outer magnetic pole 3 having an opposite polarity so as to surround it. The target material 1 is usually used by pasting it on a backing plate made of non-magnetic material such as steel or stainless steel, but in this specification, the backing plate is omitted because it does not affect the distribution of the magnetic field. It is depicted. Reference numeral 4 denotes a coil, which excites the inner magnetic pole 2 by passing a current through it. Note that each magnetic pole 2.3 may use a permanent magnet instead of an electromagnet. Each of these parts is housed in a vacuum container. In use, while applying an excitation current to the coil 4 and applying a magnetic field to the target material 1 in the direction of the arrow shown in the figure, the target material 1 is heated with, for example, Ar ions.
is used to apply sputtering to a workpiece (not shown).

FIG. 11 shows another example of a conventional magnetron sputtering device, and the difference is that the device in FIG. 10 has a rectangular shape, whereas it has a circular shape.

Now, in Figures 10 and 11, the inner and outer magnetic poles 2
, 3, the component parallel to the target material 1 captures electrons ejected from the surface of the target material 1, thereby promoting ionization of gas molecules, thereby enabling high-speed sputtering.

[Problem to be solved by the invention]

In such a conventional magnetron scanner, electrons captured near the surface of the target material 1 are confined within a semicircular arc-shaped magnetic field dome shown by the arrow in FIG. 10, and move along the dome. .

Therefore, the degree of sputtering on the surface of the target material 1 depends not only on the horizontal distribution of the magnetic field on the upper surface of the target material 1, but also on the distribution of the vertical component.

In FIGS. 12(a) and 12(b), the target material 1 is a ferromagnetic material (
The horizontal and vertical components of the magnetic field on the upper surface of the target material 1 (on the PA Pa line in FIG. 10) in the case of iron, cobalt, etc.) before and after the progress of erosion are shown by solid lines and dotted lines, respectively.

Moreover, FIG. 13 is a sectional view showing the state of erosion of the target material 1 between PA and PR in FIG. 10. As can be seen from this figure, there was a problem in that the second lotion portion progressed locally and the life of the target material 1 was significantly shortened.

Furthermore, when the target material 1 is a ferromagnetic material, as shown in FIG. 12, the magnetic field distribution on the top surface of the target changes as erosion progresses, the sputtering conditions change, and the distribution of the film thickness changes. There was a problem that physical properties changed over time.

The inventor believes that when erosion progresses, it is not directly related to the distribution of the strength of the horizontal component of the magnetic field, but is often caused by a change in the polarity of the vertical component of the magnetic field, that is, the vertical component becomes more dominant. I found a solution. This is because, in Fig. 10, the electrons move along the dome-shaped magnetic field on the surface of the target material 1, and at the same time, they also move periodically in the direction of the vertical magnetic field gradient. This is thought to be because the concentration of the electrons becomes high near the point where the component becomes a drop. Further, when erosion of the target material 1 occurs, the leakage magnetic field increases as shown in FIG. 12(b), and the gradient of the vertical magnetic field at that location also becomes steeper, so that the local two-lotion progresses further.

This invention was made to solve the above-mentioned drawbacks, and it prevents the occurrence of erosion as much as possible, extends the life of the target material, and at the same time expands the sputtered area on the target surface. In order to keep the magnetic field distribution near the top surface of the target almost constant even as erosion progresses,
It is an object of the present invention to provide a magnetron sputtering apparatus which has the advantage that the thickness distribution and physical properties of a film formed on a substrate are uniform, and there is almost no change over time.

[Means to solve the problem]

The magnetron sputtering apparatus according to the present invention is a planar magnetron sputtering apparatus having an inner magnetic pole, an outer magnetic pole surrounding the inner magnetic pole and having an opposite polarity, and a target material disposed astride both magnetic poles. In order to reduce the gradient of the component perpendicular to the target material of the leaking magnetic field from 4M at the center between both magnetic poles outside the target material, and gradually increase the gradient of the perpendicular component of the leakage magnetic field toward both magnetic poles, the length A soft magnetic material divided into a plurality of parts in the direction is provided between the inner magnetic pole and the outer magnetic pole on the back side of the target material.

(Function) In the present invention, outside the target material, the intensity and the gradient of the vertical magnetic field at the central part between the inner and outer magnetic poles are reduced, and the gradient of the vertical magnetic field is increased at the part near the two magnetic poles. Furthermore, even as erosion progresses, the magnetic field distribution near the top surface of the target is kept constant, so the magnetron mode is kept stable during sputtering, preventing local erosion, and improving the thickness of the deposited film and its physical properties. Changes in value over time are also prevented.

〔Example〕

FIG. 1 shows an embodiment of the present invention, and is a sectional view corresponding to the PA-pH portion in FIG. 10. In this figure, numerals 1 to 4 are the same as in FIG. 10, and 5 is a plurality of soft magnetic bodies according to the present invention arranged so that the mutual gap length is 1150 to 1 of the plate thickness, It is placed with a gap in between and the target material 1 . Note that the soft magnetic material 5 may be anything as long as it is easily magnetized by the magnetic field created by the magnetic poles.

Next, the effect will be explained.

The soft magnetic body 5 has magnetization in the same direction as the magnetization direction in the target material 1 due to the magnetic field created by both magnetic poles 2.3, and the soft magnetic body 5 has magnetization in the same direction as that in the target material 1,
．． It acts to reduce the absolute value of the horizontal magnetic field and the gradient of the vertical magnetic field at the center between the three. Further, near the tops of both magnetic poles 2 and 3, the influence of the magnetic field due to the soft magnetic body 5 is small, and as a result, the gradient of the vertical magnetic field near both magnetic poles 2.3 increases.

The soft magnetic material 5 acts as a magnet to cancel the magnetic field on the upper surface of the target material 1, and as the erosion of the target material 1 progresses and the leakage magnetic field on the target material 1 increases, the magnetization strength of the soft magnetic material 5 increases. This has the effect of preventing the leakage magnetic field on the target material 1 from increasing and preventing erosion from increasing locally.

FIGS. 2(a) and (b) show pA-p of the example of FIG.
FIG. 4 is a diagram showing the horizontal component and vertical component of the magnetic field before and after erosion in between.

In these figures, the solid curve shows the state before erosion, and the dotted curve shows the state after the second lotion. In addition, Fig. 3 (a), (b)
) shows the state of erosion in the PA-28 portion of FIG.

As shown in FIG. 3(a), the V-shaped erosion that is seen when sputtering is performed using a conventional magnetron sputtering device is not observed, and the erosion occurs relatively uniformly over a wide range. As shown in (b), even if the thickness of the target material 1 becomes about 10% of the original thickness, no local erosion occurs.

Figures 4 and 5 show Tb in a thin film formed on a substrate using a Tb-Fe alloy target material 1.
This is a comparative example of the change in concentration distribution in the radial direction from the center position of the target material 1 over time using the conventional magnetron sputtering apparatus shown in FIG. 10 and the magnetron sputtering apparatus according to the present invention. Two lotions are progressing according to the curve a''-c.Target material,
The lifespan of 1 is about twice that of conventional magnetron sputtering equipment, and the magnetic field distribution on the target material 1 remains almost constant even as the second rouge progresses. As can be seen, the device according to the present invention hardly changes over the life of the target, whereas the conventional type undergoes changes over time.

Figure 6 shows the patent application filed in 1988, proposed by the present inventor.
This figure shows the change over time in the Tb distribution in a thin film when using the magnetron sputtering device improved using a plate-shaped soft magnetic material, as shown in No. 31 (corresponding to FIGS. 4 and 5). As shown in FIG. 6, no change occurs over time until the erosion of the target material 1 reaches about 1/2 of the original thickness;
If it exceeds 0%, the Tb distribution will change over time. This is because the target material 1 becomes thinner and the perpendicular magnetic field created by the soft magnetic material 5 becomes curve B I + B as shown in FIG. 7(a).
2 * When the magnetic field becomes gradually stronger as shown in B3, the magnetic field created by the soft magnetic material 5 becomes dominant over the vertical magnetic field created by the magnetic pole and target material 1 shown by curve A, and the combined magnetic field is as shown in Figure 7 (b
) is the vertical magnetic field distribution with an inflection point as shown in
This is thought to be due to a bias in plasma density. In addition,
Ll+L2 is where the plasma density becomes high. This is because, in the case of a continuous soft magnetic material 5' with a constant cross-sectional area, the magnetic flux φ protrudes into the space near both ends, as shown in FIG. This is because the continuous soft magnetic material 5' is easily strongly magnetized by the increased magnetic field due to the thinning of the material.

FIGS. 8(b) and (C) show the case where a plurality of soft magnetic bodies 5 according to the present invention are used, and since the plurality of soft magnetic bodies 5 have a gap between them, the magnetization of the soft magnetic bodies 5 is large. In this case, the accumulation of magnetic flux near the gap also increases, and the resulting demagnetizing field inside the soft magnetic body 5 prevents the soft magnetic body 5 from becoming suddenly magnetized. Therefore, as the target material 1 becomes thinner and the vertical gradient on the upper surface of the target becomes larger, as shown in FIG. 9(a), the soft magnetic material 5
The vertical magnetic field in the opposite direction created by curve 81B2. The combined magnetic field with the vertical magnetic field created by the magnetic pole and target shown by curve A, which gradually increases as shown in B3, is shown in Figure 9 (b).
As shown in FIG. 2, there is no large curve with an inflection point, and even if the target material 1 becomes sufficiently thin, there is no deviation of the plasma, and there is almost no change in sputtering conditions over time. The magnetization strength of the soft magnetic material 5 is controlled by the gap length between the soft magnetic materials 5 and the number of divisions of the soft magnetic material 5.

In other words, if the number of divisions and the gap length are increased, the soft magnetic material 5
The magnetization becomes gentler, which has the effect of preventing the magnetization in the portions near the magnetic poles 2.3 from becoming too large.

Furthermore, although the present invention is particularly effective for the target material 1 made of ferromagnetic material, the erosion region can also be expanded in the case of target material made of non-magnetic material.

〔Effect of the invention〕

As explained above, this invention reduces the gradient of the component perpendicular to the target material of the leakage magnetic field from the inner magnetic pole and the outer magnetic pole outside the target material at the center of both magnetic poles, and gradually increases the gradient near both l1fi poles. In order to increase the vertical magnetic field, a plurality of soft magnetic bodies were installed in the length direction in the magnetic field formed between the inner and outer magnetic poles on the back side of the target material, so that the gradient of the vertical magnetic field of the target material decreased and the vertical magnetic field The area where the lif! Near the gap between the poles, the gradient of the vertical l1ri field becomes large, which prevents electrons from deviating from the top surface of the target, so the magnetron mode is kept stable and the target material is eroded uniformly, extending the life of the target material. In addition, since the magnetic field distribution hardly changes even if the erosion of the target material progresses, there is no change in sputtering conditions over time, and there is an advantage that a stable thin film can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the main parts showing one embodiment of the present invention;
Figures (a) and (b) are diagrams showing the horizontal and vertical components of the magnetic field before and after erosion in the embodiment of Figure 1, and Figures 3 (a) and (b) illustrate the erosion state according to the present invention. 4 and 5 are cross-sectional views of essential parts, and FIGS. 6 and 5 are diagrams showing Tb temperature distribution when using a Tb-Fe alloy target material by a conventional magnetron sputtering apparatus and a magnetron sputtering apparatus of the present invention, respectively. The figure shows the same Tb concentration distribution as in Figure 5 using the previously proposed magnetron sputtering device. Figures 7 (a) and (b) show the strength of the magnetic field and Relationship diagram with distance, Figure 8 (a), (b), (C) is a diagram for explaining the shape of soft magnetic material and the state of magnetic flux, Figure 9 (a), (b)
10 and 11 are perspective views of essential parts showing an example of a conventional magnetron sputtering device, respectively,
12(a) and 12(b) are diagrams showing the horizontal and vertical distribution of the magnetic field before and after the progress of erosion on the upper surface of the target material by a conventional magnetron sputtering device;
The figure is a sectional view showing the state of erosion between PA and PB in FIG. 10. In the figure, 1 is a target material, 2 is an inner magnetic pole, 3 is an outer magnetic pole, 4 is a coil, and 5 is a soft magnetic material. Figure Figure Figure 1 Tardesito and 1νfP+5's subject theory Figure Figure 1 Tarde W)? lV force゛94N! Male Fig. 1 (Bouquet 1.) Fig. Fig. Fig.]O

Claims (1)

[Claims] In a planar magnetron sputtering apparatus having an inner magnetic pole, an outer magnetic pole surrounding the inner magnetic pole and having an opposite polarity, and a target material disposed astride both of these magnetic poles, the leakage magnetic field from both the magnetic poles may be applied to the target material. In order to reduce the gradient of the component perpendicular to the magnetic field outside the target material at the center between the magnetic poles, and gradually increase the gradient of the vertical component of the leakage magnetic field toward the magnetic poles, A magnetron sputtering apparatus characterized in that a divided soft magnetic material is provided between the inner magnetic pole and the outer magnetic pole on the back side of the target material.