JP3272202B2 - Magnetic field generator for magnetron plasma - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic field generator for a magnetron plasma for generating a magnetic field having good magnetic field uniformity. It is suitable for use in magnetron sputtering or magnetron etching performed in the industrial field.

[0002]

2. Description of the Related Art Conventionally, magnetron plasma has been used for performing sputtering and etching.
The magnetron plasma is produced by a magnetron device as follows. First, an electrode is inserted into a gas such as argon in a container and discharged, whereby the gas is ionized and secondary electrons are generated. The secondary electrons also collide with gas molecules and the gas is further ionized. At this time, the electrons and secondary electrons emitted by the discharge receive a force due to a magnetic field and an electric field generated by the magnetron device, and drift. Therefore, when the electrons make a drift motion, they can collide with gas molecules one after another, and can ionize the gas one after another. Upon the ionization, another electron is generated, and the electron also collides with a gas molecule to further ionize the gas. The magnetron plasma repeats such a process and has a very high ionization efficiency. As described above, when the magnetron device is used, the ionization rate of the gas is high, and high-density plasma can be generated. For this reason, the method using the magnetron device for sputtering and etching has an advantage that the efficiency can be obtained two to three times as compared with the case where the normal high-pressure discharge method is used.

FIG. 5 shows an example of a sputtering apparatus using a conventional magnetron discharge device. FIG. 5A is a longitudinal sectional view of the sputtering apparatus, and FIG. 5B is a view showing the movement of electrons in this apparatus. A substrate 14 and a target 16 are provided between the parallel plate electrodes 10 and 12 to form an electrode.
A magnetic field generator 18 for magnetron plasma is installed on the back surface of 12. Although a high frequency is normally applied between the electrodes 10 and 12, the direction of the electric field when the electrode 10 is an anode and the electrode 12 is a cathode is indicated by an arrow 20 in FIG. The conventional magnetron plasma magnetic field generator 18 shown in FIG.
Disc-shaped permanent magnet 24 in the hole of donut-shaped permanent magnet 22
Are provided, and their lower surfaces are connected by a yoke 26. This conventional magnetic field generator for magnetron plasma 18
The state in which the magnetic field generated by is leaking onto the target 16 is shown by magnetic force lines 28a and 28b. The magnetic field lines 28a and 28b of the leakage magnetic field on the surface of the target 16 by the conventional magnetron plasma magnetic field generator 18 are perspectively like the magnetic field lines 30 in FIG. 5B, where the direction of the electric field is When in the direction of the arrow 20, the electron 32 follows an endless orbit 34 while drifting in the direction of the cross product of the electric field and the magnetic field. As a result,
Is bound near the surface of the target 16 and promotes gas ionization. Therefore, the apparatus shown in FIG. 5 can generate high-density plasma.

[0004] By the way, what contributes to the drift motion of electrons is a component perpendicular to the electric field of the magnetic field. That is, in the case of FIG. 5, only the component horizontal to the target contributes to drifting the electrons to ionize the gas. In a magnetron sputtering apparatus using a magnetron plasma magnetic field generator as shown in FIG. 5, a donut-shaped magnetic field is formed (see FIG. 6 (a)), and the horizontal component of the magnetic field varies greatly depending on the location, and the horizontal magnetic field component is strong. Higher density plasma is generated in the region (see FIG. 6B). Therefore,
In a region where the horizontal magnetic field component is strong, larger sputtering occurs, and the target is partially consumed, thereby lowering the use efficiency of the target. In general, targets are expensive and are an economic problem. Further, even in a magnetron etching apparatus using a similar magnetron plasma magnetic field generator, quality problems occur, such as intensive etching of a part of the wafer. Further, since the non-uniform plasma causes a potential distribution in the wafer surface (charge-up), the device is destroyed.

[0005] In order to solve such a problem, a horizontal magnetic field generator in which a magnetic field component is uniform is desired. For example,
As an apparatus for obtaining a uniform horizontal magnetic field, a dipole ring magnet in which a plurality of anisotropic segment columnar magnets are arranged in a ring shape is known. Incidentally, the magnetic field of the dipole ring magnet is a horizontal magnetic field oriented in only one direction, unlike the donut-shaped magnetic field of the conventional device (FIG. 5). For this reason, in this state, the electrons perform a drift motion and proceed in one direction, resulting in uneven plasma density. Therefore, it is necessary to rotate the dipole ring magnet along the circumferential direction of the ring in order to change the direction of the electron drift motion. However, in practice, it is not possible to make the plasma density uniform over a wide range simply by rotating the dipole ring magnet.

FIG. 3A is a top view of the dipole ring magnet, and FIG. 3B is a sectional view of FIG. 3A taken along the line AB. A plurality of anisotropic segment columnar magnets 40 are housed in a non-magnetic mount 42 to form a dipole ring magnet. Here, the case where the number of the anisotropic segment columnar magnets 40 is 16 is shown. The arrow drawn in the anisotropic segment columnar magnet 40 indicates the direction of magnetization of the anisotropic segment columnar magnet. When the direction of magnetization is arranged as shown in FIG. 3, a magnetic field having a direction indicated by an arrow 43 is generated in the ring.

When this dipole ring magnetic field is used in a magnetron plasma magnetic field generator, a substrate 38 and a target 39 are provided between parallel plate electrodes 36 and 37. Normally, a high frequency is applied between the electrodes 36 and 37.
Arrows 44 and 45 show the directions of the electric field when the electrode plate 36 is an anode and the electrode plate 37 is a cathode. At this time, it is preferable that the center cross section of the dipole ring magnet in the length direction coincides with the center cross section of the plasma space 46 where the plasma is generated (FIG. 3).
(B)). That is, the position of the target is adjusted in the case of sputtering, and the position of the wafer is adjusted in the case of etching so as to match the cross section of the dipole ring magnet in the longitudinal direction. This is because the magnetic field uniformity at the central part in the length direction of the dipole ring magnet is better than the magnetic field uniformity at the end parts, and in the central part in the longitudinal direction, only the horizontal component of the magnetic field exists in principle For this reason, if the central portion is a space where the plasma is generated, the generated plasma can be made more uniform.

A uniform magnetic field can be obtained in the plasma space 46 by the magnetic field generator composed of the dipole ring magnet, but the electrons drift in the direction of the cross product of the electric field and the magnetic field, and the electrons move in the Y-axis direction shown in FIG. Proceeding in the negative direction, the plasma density is low in the positive direction of the Y-axis, and the plasma density is high in the negative direction of the Y-axis (see FIG. 4B). Therefore, it is necessary to rotate the dipole ring magnet along the circumferential direction of the ring in order to change the direction of the electron drift motion, but in practice, the rotation of the dipole ring magnet alone cannot make the plasma density uniform over a wide range. .

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the above-mentioned points and to obtain a uniform plasma over a wide area by using a dipole ring magnet in a magnetic field generator used for a sputtering or etching apparatus utilizing magnetron plasma. It is an object of the present invention to provide a magnetron plasma magnetic field generator capable of performing the above.

[0010]

SUMMARY OF THE INVENTION The present invention is an improvement of a dipole ring magnet. In a magnetic field generator for magnetron plasma used in a magnetron device for generating high density plasma, a plurality of anisotropic segmented columnar magnets are provided. A magnetic field generated by a dipole ring magnet arranged in a ring shape and generated by the dipole ring magnet
And the outer product direction of the electric field formed in this device
If the direction, the length of the plurality of columnar anisotropic segment magnets as low magnetic field gradient in the negative direction increases in the positive direction of the Y-axis to the magnetic field intensity distribution in the longitudinal direction of the central plane of the dipole ring magnet is attached A gap is provided at a central portion in the direction, and the size of the gap is set to a size corresponding to the location of each of the anisotropic segment columnar magnets in the dipole ring magnet. This is used in a magnetron device that produces a high-density plasma to obtain a uniform plasma density distribution.

The details of the present invention will be described below. FIG. 1A shows a dipole ring magnet of the magnetron plasma magnetic field generator of the present invention. FIG. 1A is a top view of a dipole ring magnet, and FIG. 1B is a cross-sectional view of FIG. 1A taken along line G-H. 16 anisotropic segmented columnar magnets 50 (1) to 50 (1)
6) is accommodated in a non-magnetic frame 52 to form a dipole ring magnet. Arrows drawn in the respective anisotropic segment columnar magnets indicate the directions of magnetization of the anisotropic segment columnar magnets. When the direction of magnetization is arranged as shown in FIG. 1A, a magnetic field having a direction indicated by an arrow 53 is generated in the ring. The dipole ring magnet of the present invention has a gap in the center of the anisotropic segmented columnar magnet in the length direction of the conventional dipole ring magnet (FIG. 3), and the magnetic field of the center cross section in the length direction of the dipole ring magnet is provided. Fig. 2 (a)
As shown in FIG. 3, the distribution has a magnetic field gradient that is high in the positive direction of the Y-axis and low in the negative direction. It is necessary that the size of the gap be smaller in a region with a higher magnetic field strength and be larger in a region with a lower magnetic field strength.Therefore, the size 55 of the gap depends on the position of the anisotropic segment columnar magnet in the Y-axis direction. I can decide. These anisotropic segmented columnar magnets 50 are cut at the center in the longitudinal direction to form gaps 54.
(1) to 54 (16) are provided. These are also shown in FIG.
(A), the gap 54 is obtained from the symmetry of the structure in the Y-axis direction.
54 (1) = 54 (9) 54 (2) = 54 (8) 54 (3) = 54 (7) 54 (4) = 54 (6) 54 (10) = 54 (16) 54 (11) = 54 (15) 54 (12) = 54 (14) The dimensions 55 (1) to 55 (16) of the gap between the anisotropic segmented columnar magnets in the present invention are as follows, for example. Here, L represents the length of the anisotropic segment columnar magnet. 55 (1), 55 (9) = 0.81 Lmm 55 (2), 55 (8) = 0.72 Lmm 55 (3), 55 (7) = 0.61 Lmm 55 (4), 55 (6) = 0.55 Lmm 55 ( 5) = 0.51Lmm 55 (10), 55 (16) = 0.78Lmm 55 (11), 55 (15) = 0.95Lmm 55 (12), 55 (14) = 0.94Lmm 55 (13) = 0.89Lmm

The composition, number, arrangement, and configuration of the anisotropic segmented columnar magnets may be the same as those of a conventional dipole ring magnet. This is a dipole ring magnet in which a plurality of anisotropic segment columnar magnets 50 are housed in a non-magnetic mount 52. The number of the anisotropic segmented columnar magnets 50 is eight or more and is usually selected from 8 to 64. FIG. 1 shows the case of 16 pieces. The cross-sectional shape of the anisotropic segment columnar magnet is arbitrary, and may be, for example, a circle, square, rectangle, or trapezoid. In this embodiment, a square is used. The arrow drawn in the anisotropic segment columnar magnet 40 indicates the direction of magnetization of the anisotropic segment columnar magnet. When the direction of magnetization is arranged as shown in FIG. 1, a magnetic field having a direction indicated by an arrow 53 is generated in the ring. Examples of the anisotropic segment columnar magnet include a rare earth magnet such as a cylinder, a prism, and a trapezoidal column, a ferrite magnet, and an alnico magnet. FIG.
Shows only the dipole ring magnet and omits other parts of the magnetic field generator for magnetron plasma, but this may be performed in the same manner as in the case of the conventional dipole ring magnet as shown in FIG.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to examples and comparative examples. Example In FIG. 1 (a), 16 of anisotropic segmented columnar magnets 50 (1) to 50 (16) made of a prismatic Nd-Fe-B based magnet and measuring 30 mm × 30 mm in length (L) 150 mm. Piece, the size of the gap 55 (1)
1 (a), a dipole ring magnet arranged as shown in FIG. 1 (a) was installed in a magnetron plasma magnetic field generator, and a horizontal magnetic field in a plasma space 56 having a central cross section was prepared. The distribution and plasma distribution were measured as follows. The results are shown in FIGS.
As shown in (b), the magnetic field distribution in the Y-axis direction shows a high magnetic field gradient in the positive direction and a low magnetic field gradient in the negative direction, resulting in a uniform plasma distribution.

Comparative Example 1 A dipole ring magnet was prepared by arranging 16 anisotropic segment columnar magnets (having no gap) as in the example as shown in FIG. The horizontal magnetic field distribution and the plasma distribution were measured by installing it on the generator. The results are shown in FIGS. 4 (a) and 4 (b),
According to this, the horizontal magnetic field distribution is uniform in both the X-axis and Y-axis directions, but the plasma distribution is not uniform.

Comparative Example 2 As a comparison, the horizontal magnetic field distribution and the plasma distribution by a magnetron plasma magnetic field generator (shown in FIG. 5A) which is currently used industrially are shown in FIGS. 6A and 6B.
(B). The measurement of the horizontal magnetic field distribution and the plasma distribution was performed as follows. Horizontal magnetic field distribution measurement method The Hall element is moved in the evaluation space, and the value at the measurement point is read by a Gauss meter. Measurement method of plasma distribution The probe is moved in the evaluation space by the electrostatic probe method, and the current-voltage characteristics when a voltage is applied to the probe are measured. From the current-voltage characteristics, the plasma such as electron temperature and electron density is measured. Obtain various quantities and obtain the plasma distribution.

[0016]

According to the magnetic field generator for magnetron plasma of the present invention, it is possible to generate a uniform plasma over a wide area as compared with the prior art. Therefore, when the magnetic field generator for magnetron plasma of the present invention is used for sputtering. Has a great advantage that the use efficiency of the target can be increased and high quality etching can be performed even when used for etching.

[Brief description of the drawings]

FIG. 1 is a top view of a magnetron plasma magnetic field generator including a dipole ring magnet of the present invention.
FIG. 2B is a diagram illustrating a cross-sectional portion when FIG. 1A is cut along GH.

FIG. 2 is a diagram showing (a) a horizontal magnetic field intensity distribution and (b) a plasma distribution generated by the magnetic field generator of the present invention.

3A and 3B are a top view and a top view, respectively, of a magnetron plasma magnetic field generator including a conventional dipole ring magnet.
FIG. 4 is a cross-sectional view of FIG. 3A taken along the line AB.

FIG. 4 is a diagram showing (a) a horizontal magnetic field intensity distribution and (b) a plasma distribution generated by a conventional dipole ring magnet magnetic field generator.

5A is a longitudinal sectional view of a magnetron plasma apparatus including a conventional magnetic field generator, and FIG. 5B is a view illustrating movement of electrons in the apparatus.

FIG. 6 is a diagram showing (a) a horizontal magnetic field intensity distribution and (b) a plasma distribution generated by the conventional magnetic field generator using the magnet of FIG.

[Explanation of symbols]

 10, 12, 36, 37 ... electrodes 14, 38 ... substrate 16, 39 ... target 18 ... magnetron plasma generator 20, 44, 45 ... direction of electric field 22 ... donut-shaped permanent magnet 24 ... disk-shaped permanent magnet 26 ... yoke 28a , 28b, 30 ... magnetic field lines 32 ... electrons 34 ... endless orbits 40, 50 ... anisotropic segmented columnar magnets 42, 52 ... mount 43, 53 ... magnetic field direction 46, 56 ... plasma space 54 (1) ~ 54 (16) … Gap 55 (1) to 55 (16)… Gap dimensions

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H05H 1/46 C23F 4/00 H01J 23/02

Claims (2)

(57) [Claims] 1. A high-density plasma magnetic field generator for magnetron plasma, which is used by installing to a magnetron apparatus for generating, consists dipole ring magnet in which a plurality of columnar anisotropic segment magnets in a ring shape, the
The magnetic field generated by the dipole ring magnet and this device
If the direction of the outer product with the electric field formed in the direction is the negative direction of the Y axis, the magnetic field strength distribution in the center cross section of the dipole ring magnet in the longitudinal direction includes a magnetic field gradient that is high in the positive direction of the Y axis and low in the negative direction. A magnetic field generator for a magnetron plasma, wherein a gap is provided at a central portion of the plurality of anisotropic segmented columnar magnets in the longitudinal direction so as to be attached. 2. A magnetron magnetic field generator installed and used in a magnetron apparatus for generating high-density plasma, comprising: 16 anisotropic segmented columnar magnets;
Consisting of dipole ring magnets arranged in a ring shape,
A magnetic field generated by the dipole ring magnet;
The direction of the cross product with the electric field formed in the device is defined as the negative direction of the Y axis.
The length of the 16 anisotropic segmented columnar magnets
A gap is provided at the center in the direction, and the dimension of the gap is relative to the Y axis.
And the magnet moves from the positive direction of the Y-axis to the negative direction.
One in the order of 0.51L, 0.55L,
0.61L, 0.72L, 0.81L, 0.78L, 0.95L, 0.94L gap
2 pieces each with a size between them, with a gap size of 0.89L
1 piece (where L is the length of the anisotropic segmented columnar magnet)
Represents ) . A magnetic field generator for a magnetron plasma.