JPS62263966A - Magnetron sputtering method - Google Patents

Abstract

PURPOSE:To prevent the local erosion of a target by regulating the distance of the parallel spacing from the respective surfaces of an annular permanent magnet and a central permanent magnet to the surface of a target so as to levelly enlarge the region where the vertical parts of magnetic flux density come close to zero on a target. CONSTITUTION:A magnetron 18 consisting of an annular permanent magnet 12, a permanent magnet 14 located in the center of the above magnet 12, and a yoke supporting both permanent magnets 12, 14 is disposed in a vacuum tank. The distance of the parallel spacing H from the respective surfaces of both these permanent magnets 12, 14 to the target 22 surface is set up to the range of magnet diameter (D)X0.30-0.02. By the above spacing regulation, the range where the vertical components of magnetic flux density in the magnetic field generated from the magnetron 18 come as close as possible to zero on the target 22 is enlarged. As a result, the target 22 can be eroded over the wide range at the time of sputtering.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a magnetron that effectively prevents local erosion of a target during sputtering, thereby making it possible to use the target economically. This invention relates to a sputtering method.

BACKGROUND OF THE INVENTION Sputtering methods, along with vacuum evaporation methods, are widely used as technologies for forming various alloy thin films with good reproducibility on substrates such as silicon wafers in semiconductor ICs, for example. In this sputtering, for example, in a vacuum chamber filled with argon gas, a target that will become the base material for the alloy thin film is placed on a cathode plate, and a high voltage is applied to this cathode plate and a substrate placed opposite the target. This is a phenomenon in which ions are ionized from argon gas, and these ions collide with the target, thereby ejecting (sputtering) metal atoms. The released metal atoms are attracted to the surface of the anodically charged substrate, forming a uniform thin metal film.

As a means of accelerating the rate of thin film formation on this substrate, the Magneto-Ron sputtering method has been adopted. This involves generating a magnetic field using a magnetron using a permanent magnet, making the magnetic field and electric field orthogonal to generate high-density plasma near the target, concentrating a large amount of argon ions on the target, and removing metal from the target. It promotes the release of atoms. For example, the magnetron sputtering apparatus shown in FIG. 1 includes an annular permanent magnet 12, a permanent magnet 14 located in the center of the annular magnet 12, and both permanent magnets 12 and 14 supported in an airtight vacuum chamber 10. The magnetron 18 includes a yoke 16 and a magnetron 18. The magnetron 18 is internally supported by a conductive frame 20, and a target 22 made of a metal base material such as molybdenum is mounted on the magnetron 18 and the frame 20.
is mounted removably (a backing plate, not shown, may be interposed between the target and the magnetron).

In this case, if the magnetic pole on the side of the annular permanent magnet 12 facing the target 22 is the north pole, the magnetic pole on the side of the central permanent magnet 14 facing the target 22 is set in advance to be the south pole. The frame body 20, which contacts and supports the target 22, is connected to the cathode side of a DC high voltage power source, and the substrate 24, such as a silicon wafer, placed opposite to the target 22 is connected to the anode side. It has become.

Problems to be Solved by the Invention This magnetron sputtering device has a
When a high voltage of 0V is applied to the substrate 24 and the support frame 20, a glow discharge is generated between the substrate 24 and the target 22. As a result of the discharge concentrating in an annular manner near the target where the electric field and magnetic field are perpendicular to each other, a high-density argon plasma is generated in the discharge space, and the positive argon ions in this plasma are accelerated and cathodically charged. The ejection of metal atoms is promoted by impinging on the surface of the target 22 and sputtering the target surface.

For this reason, as shown in FIG. 2, the surface of the target 22 is locally eroded (2 lotions) where the argon positive ions collide, which has the drawback that the effective use area of the target is limited. . Furthermore, if this eroded portion penetrates the target, the target cannot be used anymore, which is extremely wasteful, even if other portions maintain a healthy wall thickness. In order to overcome this drawback, attempts have been made to change the number of permanent magnets used in the magnetron, change the magnetic pole arrangement, etc., but these methods result in an increase in cost. It could not be an effective method.

Purpose of the Invention The present invention provides a magnetron that can be used economically by preventing local erosion by eroding a target over a wide range of areas when performing sputtering using the magnetron sputtering apparatus described above. The purpose is to provide a sputtering method.

Means for Solving the Problems In order to overcome the above-mentioned problems and achieve the desired objectives, the method according to the present invention comprises a magnetron comprising an annular permanent magnet and a permanent magnet located in the center thereof. When performing sputtering between an anodically charged substrate and a cathodically charged target using a magnetron sputtering device, the perpendicular component of the magnetic flux density in the magnetic field generated from the magnetron flattens a region on the target that is as close to O as possible. The parallel spacing distance from the surfaces of the annular permanent magnet and the center permanent magnet to the target surface is adjusted so as to increase the target surface.

EXAMPLE Next, a preferred example of the magnetron sputtering method according to the present invention will be described. The magnetron sputtering apparatus in which the invention is implemented is the apparatus itself described in connection with FIG. First, as mentioned above, the reason why the target is locally eroded during magnetron sputtering is that the magnetic flux density distribution of the magnetic field generated from the magnetron 18 on the surface of the target 22 is not uniform, but is concentrated in an annular shape. . This magnetic flux density is generally expressed as a vector that is a combination of a component in a direction perpendicular to the magnet surface and a component in a direction parallel to the magnet surface. The inventor has found that the vertical component B soil appears to be closely related to defining the plasma generation area described above.

In other words, the vertical component B soil with high magnetic flux density serves as a wall that defines the plasma generation area, and therefore, the vertical component B soil that serves as the wall is positioned as far as possible radially outward from the target. It turns out that the more you do this, the wider the plasma generation area becomes.

For example, the magnetic flux density distribution diagram shown in FIG. 3 shows the magnetic flux density (Gauss) on the vertical axis and the radial distance (m) of the annular permanent magnet 12 on the horizontal axis. The distribution of B soil in the vertical direction is plotted for each measurement point above the magnet surface. The diameter of the annular permanent magnet 12 used in the example is 200Iff1.
It is 1. According to this graph, B10. B top 20
and 27 on B (10nwn above from the magnet surface, respectively)
In both cases, the magnetic flux density (measured at a position of 20+nm and 27Tm) is planarly expanded in a region that approaches 0 as much as possible on the magnet surface.

Therefore, we further investigated the soil so as to planarly expand the area where the vertical component of the magnetic flux density approaches O as much as possible on the target, and found that the range that satisfies this is the area where both permanent magnets 12. It has been found that there is a close relationship between the parallel spacing H from the surface to the target 22 surface and the external diameter of the annular permanent magnet 12. That is, as a result of various actual measurements, when the value obtained by dividing the parallel distance H by the magnet diameter is within a range larger than 0.02 and smaller than 0.30, the perpendicular component of the magnetic flux density is We have found that it is possible to expand the area that approaches O as much as possible in a two-dimensional manner. Expressing this as an inequality, 0.02<H/D
<0.30, where the magnet diameter is determined by the magnetron used. Therefore, the parallel distance H from the surface of the annular permanent magnet 12 to the target surface ranges from magnet diameter DX0.30 to magnet diameter DX0.0.
It will be set within the range of 2.

For example, when using an annular permanent magnet 12 with a diameter of 200 m, the parallel distance H from the surface of the permanent magnet to the target surface is 200 m x O, 30 to 200 m x 0.02 = 6
The optimum distance is between 0m and 4cm. And 10 on B shown in the graph diagram of FIG. B top 20 and B top 2
7, the parallel spacing H is 10+m+, 20■, and 2
It can be seen that the distance is 7+m, which is within the optimum interval range described above.

Effects of the Invention As described above, according to the method according to the present invention, when performing sputtering using a magnetron sputtering device,
The parallel spacing distance from the surfaces of the annular permanent magnet and the central permanent magnet to the target surface is such that the vertical component of the magnetic flux density in the magnetic field generated from the magnetron expands in plan the area on the target that approaches O as much as possible. The content is to adjust. As a result, the wall of the vertical component of the magnetic flux density, which is considered to define the plasma generation region, is present at a position expanded radially outward on the target, thereby preventing the target from being eroded over a wide range as much as possible. This has the beneficial effect of effectively preventing argon positive ions from being locally concentrated on the target surface), thus making it possible to use the target economically.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional explanatory view showing a schematic structure of a magnetron sputtering apparatus that can suitably carry out the magnetron sputtering method according to the present invention, and FIG. 2 is a schematic view showing a state in which a target is locally eroded by magnetron sputtering. Figure 3 is a magnetic flux density distribution diagram in which the vertical axis represents the magnetic flux density (Gauss) and the horizontal axis represents the radial distance (Wll) of the annular permanent magnet, and the distribution of magnetic flux in the direction perpendicular to the magnet surface. Figure 4 shows the relationship between the parallel distance H from the surfaces of both permanent magnets in the magnetron to the target surface and the external diameter of the annular permanent magnet. FIG.

Claims (2)

[Claims] (1) When performing sputtering between an anodically charged substrate and a cathodically charged target using a magnetron sputtering device equipped with a magnetron consisting of an annular permanent magnet and a permanent magnet located in the center, The parallel spacing distances from the surfaces of the annular permanent magnet and the central permanent magnet to the target surface are adjusted so that the area where the vertical component of the magnetic flux density in the magnetic field generated by the magnetron approaches 0 as much as possible on the target is expanded in plan. A magnetron sputtering method characterized by: (2) The parallel distance from the surface of the annular permanent magnet and the center permanent magnet to the target surface is set within the range of the external diameter of the annular permanent magnet x 0.30 to the external diameter of the annular permanent magnet x 0.02. Claim 1 characterized by
The magnetron sputtering method described in .