KR20080009292A - Sputtering magnetron - Google Patents

Abstract

The present invention relates to a magnetron having a planar target and a planar magnet system. The planar magnet system comprises a rod-shaped first pole and a frame-shaped second pole with enlarged ends, and the relative movement between the poles and the target is such that all points of the moving magnet system move on the circular path when the target is stationary. Is made to move. If the magnet system is stationary, each point of the target moves on such a circular path. The magnet system and the target are in parallel planes during relative movement with respect to each other. The diameter of the circular path corresponds to the average distance between two parallel arms of the plasma tube that occur during the sputter operation between the first and second poles. The magnets in the curved area of the plasma tube are arranged at this location so that the polar lines form a circular arc or circular area, so that holes in the target are prevented.

Description

Sputtering Magnetron {SPUTTERING MAGNETRON}

The present invention relates to a sputtering magnetron according to the preamble of claim 1.

purpose

Coating of substrates with thin material layers or several thin material layers plays an important role in countless technical fields.

For example, CD disks may be provided with clock housings or protective layers having a ceramic layer. Coating glass with layers that pass or reflect only certain wavelengths has become of considerable importance. Large glass outer walls are installed in buildings using so-called architectural glass provided with thin layers. The coating may also function to make the composite films or composite bottles gas-tight.

A very often employed method of coating the above listed materials is the sputtering method. In the sputtering method, plasma is generated in the vacuum chamber. Relatively high concentrations of positive and negative charge carriers and photons as well as mixtures of neutrons are understood as plasmas. The cations in the plasma are attracted by the negative potential of the cathode on which the so-called target is installed. When the cations in the plasma impinge on the target, they impinge on small particles and fall off the target, which can then be deposited on a substrate placed on the opposite side of the target. As such, knocking-out of particles is called "sputtering". Distinguish between reactive and non-reactive sputtering here. In non-reactive sputtering, work proceeds with inert gases that function as working gases, and their amounts of gas ions cause particles of the target to fall off in a collision. Reactive sputtering also employs reactive gases such as, for example, oxygen, which form a compound with the particles of the target before they are deposited on the substrate.

The ions required for the sputtering process are generated with the help of an accelerated electric field to the target forming the cathode, for example, by the collision of gas atoms and electrons in a glow discharge.

Free electrons are mainly responsible for ionization. They can be concentrated in front of the target with the aid of magnets to enhance ionization. The combination of cathode and magnets is called as magnetron. The problem encountered in magnetrons is that the target material is eroded unevenly because the magnetic field is not homogenous. For example, erosion of the target material does not occur near pole lines of magnetic fields. Polar lines mean regions in which magnetic force lines pass perpendicular to the target surface on the sputtering side. As a result of the uneven erosion of the target material, the substrate is also unevenly coated.

The aim is therefore to eliminate the disadvantages of uneven erosion.

Magnetrons in which the magnet system is moved parallel to the target material are already known (EP1120811 A2). The magnet system includes several magnets that are moved on a path parallel to the target plane. This magnet system makes the magnetic field more homogeneous, ensuring uniform erosion of the target material.

Tubular targets are employed where high target utilization may also be achieved. The magnet system moved relative to the target is located within this target, or the magnet system is fixed but the tubular target moves around the magnet system (DE41 17 367 C2)

Recently, planar magnetrons are also known which comprise several magnets which define a magnetic field in the form of a closed loop to create a plasma tube on a target. Here, devices are provided for generating a cyclical movement between the magnets and the target surface. One of these movements is circular.

Problem

The present invention addresses the problem of improving the utilization of planar and rectangular targets in sputtering.

Problem solving

The problem is solved according to the features of claim 1 of the present invention.

Accordingly, the present invention relates to a magnetron having a planar target and a planar magnet system. The planar magnet system comprises a bar-shaped first magnetic pole and a frame-shaped second magnetic pole with enlarged ends, and the relative movement between the magnetic poles and the target, in the case of a fixed target, Each movement point proceeds in a manner that moves on a circular path. If the magnet system is stationary, each point of the target moves on such a circular path. The magnet system and the target are in parallel planes while relative to each other. The diameter of the circular path corresponds to the average distance between two parallel arms of the plasma tube occurring between the first and second poles during the sputtering operation. Magnets in the curved region of the plasma tube can be arranged such that pole lines form a circular arc or circular region in this region, so that holes in the target can be prevented.

Advantages of the Invention

Advantages according to the invention include the sputtering of the target, particularly at positions where the lines of magnetic force pass perpendicularly through the magnet plane during static operation. In particular, the erosion rate occurring at the narrow side of the rectangular magnet is prevented from increasing.

1 shows a magnet configuration with inner and outer magnets and a plasma tube;

2 illustrates a magnet configuration movable on a target.

3 shows a magnet with a plasma tube in which the inner magnet is enlarged at its end;

4 shows a plasma tube with a circular integration contour.

5 shows a magnet configuration in which the ends of the inner magnets are enlarged through the magnets arranged in parallel;

6 illustrates a magnet configuration in which ends of inner magnets are enlarged by an annular magnet;

FIG. 7 shows a magnet configuration in which ends of the inner magnets are enlarged by round discs; FIG.

8 shows a drive for driving a magnet configuration with respect to a target.

1 shows a magnet configuration 1 as used in sputtering of planar targets. Such a magnet configuration is shown, for example, in FIG. 10 of US5382344.

The magnet configuration 1 is composed of a first magnetic pole (for example, N pole 2) and a second magnetic pole (for example, S pole 3). The north pole 2 has the form of a rectangular frame surrounding the rod-shaped S pole 3. The north pole 2 is composed of two long sides 4 and 5 and two short sides 6 and 7. The S pole 3 also has two long sides 8, 9 and two short sides 10, 11, while the short sides 10, 11 have short sides 6, 7 of the N pole 2. Much shorter than

Plasma tube 12 is apparent between the N pole 2 and the S pole 3, which occupies almost the entire space between the N pole 2 and the S pole 3. This plasma tube 12 is generated from a magnetic field of a magnet configuration when connected to a voltage applied to a cathode which is not shown in FIG. 1, which cathode is connected to the magnet configuration 1. The north pole 2 and the south pole 3 are connected to each other through a yoke.

A target, which is also not shown in FIG. 1, has at least the same size as the magnet configuration 1 and is arranged parallel to it. Thus, the magnet configuration 1 and the target are in parallel planes.

The plasma tube 12 may be subdivided into four regions. The two regions 13, 14 extend parallel to the long sides 4, 5 of the N pole 2, while the two other regions 15, 16 half the ends of the S pole 3. Surround semi-elliptically.

D represents the distance between the centerlines of the parallel regions 13, 14 of the plasma tube 12.

If the magnet configuration 1 is employed in the magnetron, portions of the target which are positioned opposite to the plasma tube 12 during the static operation are substantially sputtered off. The remaining areas are not substantially eroded.

2 shows the arrangement according to the invention of the magnet configuration 1 with respect to the target 20. This target 20 is rectangular and its dimensions are slightly larger than the magnet configuration 1. The N pole 2 and the S pole 3 are connected to each other via a yoke plate (not shown) so that the relative position of the S pole 3 with respect to the N pole 2 is always coincident.

In order to make the sputtering of the target 20 more uniform, the imaginary axis 21 through the S-pole configuration is rotated on the circle 22 to diameter D.

The magnet system 1 is thus moved such that each of its points circles a same diameter D. The magnet system 1 and the target 20 are in planes that are oriented parallel to each other.

When a voltage is applied to the cathode (not shown), the plasma is ignited. This forms the self-contained plasma tube 12 shown in FIG. 1, whose shape is determined by the magnetic field of the magnet configuration 1.

When moving the magnet configuration 1 with respect to the target 20, the plasma tube 12 is also moved and guided over a large portion of the fixed target surface here. Thus, the plasma tube 12 also sweeps over the areas of the target 20 that will not be sputtered in static operation.

In order to prevent the eroded target material from being redeposited onto the target surface, each position of the surface of the target 20 must be covered by the plasma tube 12 for a period of time.

The magnet arrangement 1 shown in FIGS. 1 and 2 still has the disadvantage that intensive material erosion occurs in the curved regions 23, 24 of the magnet system 1. Thus, holes are generated in the target 20 by the curved areas 23 and 24.

To prevent this hole, the inner pole is deformed in the manner shown in FIG.

In the case of the magnet arrangement 25 shown in FIG. 3, the outer magnet 2 is configured like the outer magnet according to FIG. 1.

However, the inner magnet 26 has a different form. This also comprises a rod with two long sides 27, 28 and two short sides 24, 30, but the long sides 27, 28 are shorter than in the case of the inner magnets 3 according to FIG. 1. .

The short sides 24 and 30 are in each case connected by five small bar magnets 31 to 35 or 36 to 40, respectively, forming a substantially circular body, so that the inner pole is approximately in the shape of a bone. Has Small bar magnets 33 and 38 extend parallel to the short sides 7, 6 of the outer pole, and small bar magnets 32, 34 or 37, 39 extend the long sides 4, 5 of the outer pole. Extends parallel to. The small bar magnets 31, 35 or 36, 40 make a connection between the bar magnets 32, 34 or 37, 39 and the short sides 24, 30 of the inner magnetic pole 26. They are arranged at an angle of approximately 45 degrees with respect to the longitudinal axis of the inner magnet 26.

The plasma tube 45 due to the magnet configuration 25 is shown once again in FIG. 4 without the magnet configuration 25.

The example of FIG. 4 illustrates how the amount of material eroded from the target 20 can be calculated at a particular location 42, 43, 44 of the target with the circular movement of the magnet configuration 25 over the target 20. It is to.

Plasma density is mathematically integrated along circular path 46 with diameter D for this purpose (in this regard Shunji Ido, Koji Nakamura: Computational Studies on the Shape and Control of Plasmas in Magnetron Sputtering Systems, Jpn. J. Appl. Phys. 32; 5698-5702, 1993). There, a closed contour path integral is formed. In the case of the circular path 46, this integration is zero because no plasma is found in the circular path 46.

In the case of the circular path 47, the plasma tube 45 passes through the circular path 47, so that a specific amount of value is calculated as the plasma density. Again for the circular path 48, as in the circular path 46, the value is zero.

Since the plasma in the curved regions 49 and 50 contracts, holes in the target 20 which occur when using the magnet configuration 1 according to FIG. 1 are prevented.

The contraction must be large enough to guide the plasma tube 45 on the circular path 46 around the curve, in which case the inside of the plasma tube 45 has a diameter D corresponding to the distance D shown in FIG. 1. Depict a circular path.

Such contraction can be achieved through a very wide magnet or through several narrow magnets arranged next to each other.

5 shows such a magnet configuration 52. Instead of the bar magnets 31 to 35 or 36 to 40 arranged in a quasi-circle according to FIG. 3, in the magnet configuration 52 of FIG. 5, five bar magnets 53 to 57 or 58 to 62 are in each case arranged at the short sides 29, 30 of the pole 26, in particular parallel to the long sides 4, 5 of the N pole 2.

In each case the center magnets 55 and 60 are the largest, while the laterally continuous magnets 54, 53; 56, 57 or 58, 59; 61, 62 are gradually shortened outwards.

6 shows another variant of the inner magnetic pole 26 of the magnet configuration 41. Each end 29, 30 of the rod 26 is in each case connected by a magnet ring 70, 71. In the variant of FIG. 7, disks 72 and 73 are provided instead of rings.

In FIG. 8 the magnet arrangement according to FIG. 6 is shown once again with the target 20 and the schematic drive. The yoke plate 75 is clearly shown here on the two magnetic poles 26, 2. Reference numeral 76 denotes a drive wheel in which a pin 77 connected downwardly with the yoke plate 75 is positioned around the periphery. The drive wheel 76 is connected with the upward shaft 78 which is driven by the motor 79.

If the pin 77 is arranged at a distance D / 2 from the center of the drive wheel 76 and the motor 79 is driven, the yoke plate 75 is in the manner already described, ie each point of the yoke and magnet system. Moves with the magnet system to move on a circular path. The pin 77 is not rigidly connected to the yoke plate 75 here, but rather is inserted into a hole (which can be rotated here) of the yoke plate 75, in which the yoke plate 75 is connected to the shaft ( 78) to prevent rotation around the whole. The geometric orientations (x-axis, y-axis) of the short and long sides of the yoke plate 75 remain unchanged during the rotational movement.

The pin 77 does not necessarily have to be inserted into the opening in the yoke plate 75 itself. It may also be possible to provide an additional plate connected to the yoke plate 75 for this purpose. Any other drive (EP0918351 A1, see Fig. 6) which acts on the desired movement of the magnet configuration relative to the target can be used. It is only essential that each point on the magnet configuration represents a movement on the perimeter of diameter D.

The magnets forming the ends of the rod-shaped inner pole 26 are preferably implemented such that their magnetic lines of force form an angle greater than 20 degrees with respect to the target 20 surface.

Claims (9)

Having a planar target and a planar magnet configuration, the magnet configuration comprising a rod-shaped first pole and a frame-shaped second pole, wherein the target and the magnet configuration are in communication with each other such that each point of the target moves in a circle relative to the magnet configuration. As a sputter magnetron that can be moved relative to, Sputter magnetron, wherein the ends of the rod-shaped first magnetic poles (3, 26) extend in the form of a circle. 2. The enlarged ends of claim 1, wherein the enlarged ends correspond to an average distance between two parallel arms 12, 13 of the plasma tube that occur during a sputter operation between at least the first and second magnetic poles 3, 2. Sputter magnetron having diameter D to say. The sputter magnetron according to claim 1, wherein the ends of the rod-shaped first magnetic poles (3, 26) are each formed of several small rod magnets. 4. The end portions of claim 3, wherein each end portion extends in parallel to the bar magnets 33 and 38 and the long sides 4 and 5 extending in parallel to the short sides 6 and 7 of the frame-shaped magnetic pole 2. Sputter magnetron consisting of two bar magnets (32, 34; 37, 39) and two bar magnets (31, 35) extending at an angle of about 45 degrees with respect to the longitudinal axis of the first rod-shaped pole (26). The sputter magnetron according to claim 4, wherein the small bar magnets (33, 38, 32, 34; 37, 39, 31, 35) are spatially arranged series. 4. The rod of claim 3, wherein each end extends parallel to the long sides 4, 5 of the frame-shaped magnetic pole 2 and decreases in length in the direction towards the long sides 4, 5. Sputter magnetron made of magnets 53-57. The sputter magnetron according to claim 1, wherein each end of the rod-shaped first magnetic pole (3, 26) consists of an annular magnet (70, 71). A sputter magnetron according to claim 1, wherein each end of the rod poles (3, 26) consists of circular disks (72, 73). The sputter magnetron according to claim 1, wherein the magnetic field lines of the circularly enlarged ends of the first magnetic pole (3, 26) have an angle greater than 20 degrees with respect to the surface of the target (20).

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