JPH0360916B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to an improved sputtering apparatus for forming a thin film on the surface of a substrate.

(b) Prior art and problems In general, sputtering equipment collides gas ions with a cathode target (hereinafter referred to as the target) to make the target material into atoms and deposit it on the surface of the substrate to which the anode is attached. This device is designed to generate a thin film on the top.

Such sputtering equipment is used, for example, when manufacturing semiconductor devices, and has become an essential equipment for forming aluminum electrode films and insulating films. This is because films deposited using the sputtering method have advantages over films deposited using other methods, such as a film with uniform crystal grains and ease of depositing alloy films. In particular, it is widely used for depositing aluminum electrode films. In addition, the ease of in-line (automation) is a major advantage in terms of mass production.

By the way, there are various types of sputtering equipment, but they are suitable for semiconductor substrates (semiconductor wafers).
When forming a film on a surface, a planar sputtering device is used.

On the other hand, as semiconductor substrates become increasingly larger with the advancement of semiconductor devices, the thickness of the film deposited by such a sputtering apparatus also increases.

Incidentally, in order to avoid increasing the size of the entire device, there is a tendency to process each wafer individually, but when using a normal disc-shaped target, the larger the substrate to be deposited, the smaller the distance between the negative and positive electrodes. It is necessary to make the thickness of the deposited film uniform by widening the sputtering area, but this has the disadvantage of increasing the size of the sputtering apparatus and also reduces the efficiency of using the target.

(c) Purpose of the Invention The present invention solves these drawbacks and proposes a sputtering device that is compact and capable of forming a thin film of uniform thickness even on a large substrate. It is something to do.

(d) Structure of the invention The object of the invention is to arrange a plurality of magnets on the back side of the sputtering target from the center of the sputtering target toward the periphery, and to attach each of the magnets to the sputtering target. An N-pole portion and an S-pole portion are provided opposite to each other on the back surface, and adjacent magnets in the direction from the center to the periphery of the sputtering target are arranged such that the N-pole portions or the S-pole portions face each other and are separated from each other. A sputtering ring characterized in that a plurality of ring-shaped etched areas are formed on the surface of the sputtering target in correspondence with a plurality of magnets arranged from the center toward the periphery of the sputtering target. This can be achieved by a device.

(e) Examples of the invention Hereinafter, examples will be described in detail with reference to the drawings. FIG. 1 shows a schematic sectional view of an example of a conventional sputtering apparatus, in which a substrate 3 to be deposited is held on the anode 2 side in a reaction chamber 1, and a target 5 is placed on a cathode 4 facing parallel to this. It is evacuated to vacuum through the exhaust port 6, and argon (Ar) gas is introduced through the gas inlet 7. The degree of pressure reduction is 10 ^-1 ~
10 ^-3 Torr, high frequency power of frequency 13.56MHz8
is applied to the cathode 4 to deposit the target material on the deposition substrate 3. In that case, one magnet 9 is placed on the back surface of the target, and the electron density in the electrode space is increased by the magnetic field lines of the magnet, and the Ar ⁺ ion density is increased, so the sputtering efficiency is increased by several points. It goes up twice. As the magnet 9, for example, a ring-shaped permanent magnet as shown in FIG. 2 is used. In this way, the magnet 9 has the effect of improving productivity and making the sputtering apparatus extremely efficient.

However, the presence of the magnet 9 tends to make the thickness of the deposited film non-uniform when the substrate to be deposited or the target becomes large, and this situation will be explained with reference to FIG. Figure 3 shows a 4-inch diameter semiconductor substrate as the adherend substrate 3, and an 8-inch diameter aluminum (Al) as the target 5.
The data is an example of depositing an aluminum film on a semiconductor substrate using a plate. The horizontal axis (x) is the distance from the center of the substrate, the vertical axis is the film thickness, and a in the figure shows the deposit. The distance between the board and the target is 40mm, and the figure b is 60mm.
mm, and c in the figure is for 80 mm. From this, it can be seen that the most appropriate distance between the substrate and the target is 60 mm. However, this apparatus cannot uniformly grow a 6-inch wafer. Even in Figure b, where the distance is most appropriate, the thickness of the deposited film is thinner at the outer periphery. Therefore, it is necessary to further increase the size of the target and the gap (distance) between the target substrate and the target, but this results in an increase in the size of the entire sputtering apparatus, resulting in an extremely inefficient apparatus. In addition, as shown in FIG. 4, the ratio of the etched surface portion of the target 5 with the magnet 9 close to its back side decreases, resulting in poor target usage efficiency and increased target running costs. Become.

The present invention provides a sputtering apparatus that eliminates these drawbacks, and FIG. 5 shows a schematic sectional view of a sputtering apparatus in which the target has a diameter of 10 inches as an embodiment of the present invention. The same members as in FIG. 1 are given the same reference numerals, but two ring-shaped magnets 11 and 12 are arranged concentrically with the target 5. FIG. 6 shows a perspective view of the magnets 11 and 12. FIG. 7 shows data of an example in which an aluminum film was deposited using this sputtering apparatus under the same conditions as in FIG. 3. In conventional equipment, the most appropriate distance between the substrate and target, that is, the gap at which the most uniform deposited film is formed, is supposed to be 90 to 150 mm, but because the inner ring-shaped magnet 11 is provided, , 60
The gap can be ~90mm. The data is shown in Figure 7. In figure a, the distance between the adherend substrate and target is 40 mm, in figure b 60 mm, and in figure c 80 mm.
mm, Figure d shows the case of 100 mm, but the most uniform film thickness is obtained when the distance is 60 mm, and the distribution becomes worse as the distance increases.

The greatest advantage of the present invention is that a uniform film thickness can be obtained due to the short distance, and the target usage efficiency is also improved. As mentioned above, in the conventional device using one ring-shaped magnet as shown in FIG. 1, a uniform film thickness can be obtained when the distance between the two electrodes is 90 to 150 mm. FIG. 7 shows that in a device using two ring-shaped magnets as shown in the figure, a uniform film thickness can be obtained when the distance between both electrodes is set to 60 to 90 mm.

Further, the target is formed with a plurality of etched areas (erosion areas) in the state shown in FIG. 8, and is worn out evenly, so that the efficiency of use is improved.

Furthermore, if the number of ring-shaped magnets is increased instead of just two, a more significant effect can be obtained. Also, instead of ring magnets, two sets of bar magnets can be arranged radially from the center of the target as shown in Figure 9.
It has a similar effect.

(f) Effects of the Invention As is clear from the above explanation, according to the present invention, the film thickness can be made uniform even if the distance between the two electrodes is shortened, so the sputtering device can be made smaller and the sputtering efficiency can be improved. Moreover, the efficiency of target usage improves. Therefore, the sputtering apparatus according to the present invention can be incorporated into an automated process of semiconductor manufacturing, and can be useful for high-speed processing of the process.

Note that although the above example is explained using an RF sputtering method using a high frequency power source, it goes without saying that a sputtering method using a DC power source is also similar.

[Brief explanation of drawings]

Fig. 1 is a schematic sectional view of a conventional sputtering device, Fig. 2 is a perspective view of its magnet, Fig. 3 is data obtained from the device shown in Fig. 1, and Fig. 4 is a sectional view of a conventional target after use. FIG. 5 is a schematic sectional view of the sputtering device according to the present invention, FIG. 6 is a perspective view of its magnet, FIG. 7 is data obtained by the device shown in FIG. 5, and FIG. 8 is a diagram showing the target according to the present invention after use. FIG. 9 is a perspective view of another arrangement of magnets according to the present invention. In the figure, 1 is a reaction chamber, 2 is an anode, 3 is a substrate to be adhered to,
4 is a cathode, 5 is a target, 6 is an exhaust port, 7 is a gas inlet, 8 is a high frequency power, and 9, 11, and 12 are targets.

Claims (1)

[Claims] 1. A plurality of magnets are arranged on the back side of the sputtering target from the center of the sputtering target toward the periphery, each of the magnets facing the back side of the sputtering target. N-pole portions and S-pole portions are provided, and adjacent magnets in the direction from the center to the peripheral portion of the sputtering target are arranged such that the N-pole portions or the S-pole portions face each other and are separated from each other, A sputtering apparatus characterized in that a plurality of ring-shaped etched areas are formed on the surface of the sputtering target in correspondence with a plurality of magnets extending from the center of the sputtering target toward the periphery thereof.