JP2000355764A - Magnetron cathode unit - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a magnetron cathode unit capable of suppressing significant local erosion and increasing the target use efficiency. In a rectangular magnetic field generating means, a target magnet is formed by making corner magnets (2a and 2b) stronger than linear magnets (1a and 1b).
A rectangular magnetron cathode unit with a uniform magnetic flux density in the track-shaped erosion area above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rectangular magnetron cathode unit.

[0002]

2. Description of the Related Art The magnetron sputtering method is a method of forming a magnetic field for confining electrons on the surface of a target, increasing the plasma density, and improving the film forming rate, and is used in various fields. For example, when a transparent conductive film such as an indium oxide film doped with tin or an oxide film containing zinc oxide as a main component is formed by a magnetron sputtering method, the magnetic flux density is increased and the discharge voltage is reduced to form a film. It is well known that a transparent conductive film having a low specific resistance can be obtained by performing the method (Japanese Patent Application Laid-Open Nos. 2-232358 and 9-8).
No. 7833).

It is known that in a rectangular magnetron cathode unit, auxiliary magnets are arranged to weaken the magnetic flux density at two rectangular portions where the electron density is high (Japanese Patent Laid-Open No. 8-325726). However, JP
According to the method disclosed in JP-A-325726, the portion where the magnetic flux density is weakened by the auxiliary magnet (adjacent to the center of the long side) is still locally deeply eroded. Did not connect.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a magnetron capable of suppressing a significant local erosion, making the amount of the target cut by sputtering substantially uniform within the erosion region, and improving the target utilization efficiency. The purpose is to provide a cathode unit.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above-mentioned object, and is a rectangular magnetron cathode unit used in a magnetron sputtering apparatus, wherein the magnetron cathode unit comprises:
A rectangular magnetic field forming means arranged on the back side of the target with respect to the substrate on which the thin film is to be formed, and for forming a magnetron magnetic field on the substrate-side surface of the target; The means includes a first portion that mainly forms a magnetic field on a linear portion of a track-shaped erosion region where a target is cut by sputtering, and a second portion that mainly forms a magnetic field on a curved portion of the track-like erosion region. A component horizontal to the target surface at a position where the magnetic flux density of the component perpendicular to the target surface is zero, the magnetic field being on the bisector of the long side of the rectangle formed by the first portion of the magnetic field forming means. absolute value B _a of the magnetic flux density is at 0.02 T (tesla) or more, the magnetic field forming means for forming the track-shaped erosion area Field, the magnetic flux density of the component perpendicular to the target is at the position of zero, and the absolute value B _b of the magnetic flux density of the horizontal components in the target, the absolute value B _a ratio of (B _b / B _a of the magnetic flux density ) Provides a magnetron cathode unit that is 0.9-1.1 at all points within said track-shaped erosion region.

FIG. 4 shows the erosion shape (only half) of a target when sputtering is performed using the magnetron cathode unit of the present invention. FIG. 4 shows only half of the rectangular target, and the erosion shape is annular, that is, track-like in the entire rectangular target. The “track-shaped erosion area” in the present invention refers to such a track-shaped area.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The magnetic field forming means in the present invention is not particularly limited as long as it can form a magnetron magnetic field on the surface of a target on a substrate side, and may be a coil or a magnet. Hereinafter, FIGS. 1 and 2
The magnetron cathode unit of the present invention will be described with reference to the case where a magnet is used as the magnetic field forming means as an example, but the same applies when a coil is used as the magnetic field forming means.

FIG. 1 is a plan view of an example of a magnetic field forming means in the magnetron cathode unit of the present invention, and FIG.
FIG. 2 is a schematic cross-sectional view of the magnetron cathode unit of the present invention including a cross section taken along the line AA of the magnetic field forming unit of FIG. 1. Reference numeral 1 denotes a linear magnet (1a) as a first part of the magnetic field forming means.
Is a straight portion peripheral magnet, 1b is a straight portion central magnet), 2 and 2 are corner magnets as a second part of the magnetic field forming means (2a is a corner peripheral magnet, 2b is a corner central magnet), 3 is Magnetic yoke, 4 is a backing plate, 5
Is a target, and 6 is a substrate on which a thin film is to be formed by sputtering.

The magnetron cathode unit of the present invention for a magnetron sputtering apparatus has a target 5,
Further, a target 5 is formed on a substrate 6 on which a thin film is to be formed.
And a rectangular magnetic field forming means for forming a magnetron magnetic field on the surface of the target 5 facing the substrate 6.

The magnetic field forming means mainly forms a magnetic field with respect to a linear portion of a track-shaped erosion region where a target is cut by sputtering, and mainly forms a curved portion of the track-shaped erosion region. And a second part forming a magnetic field. The magnetic field formed by the first portion is mainly for the straight portion of the track-shaped erosion region, but may also affect the curved portion. Conversely, the second part can affect the straight part.

In the case of FIG. 1, the first part of the magnetic field forming means is:
Peripheral magnet 1a located at the center of the long side of the rectangle
And a straight portion central magnet 1b disposed at the center inside the track-shaped erosion region. The second part of the magnetic field forming means includes a corner peripheral magnet 2a disposed near the end of the long side and a short side of the rectangle, and a corner part disposed near both ends inside the track-shaped erosion area. A central magnet 2b;
The corner magnet 2 is composed of:

A component perpendicular to the target surface (hereinafter simply referred to as a vertical component) of the magnetic field on the long bisecting line (A-A line) of the rectangle formed by the linear magnet 1 as the first part of the magnetic field forming means. in magnetic flux density at the zero position of the also called component), a horizontal component to the target surface (hereinafter, when simply the absolute value B _a magnetic flux density of the horizontal component and also referred to) is more than 0.02 T (in particular more than 0.05 T) In addition, the effect of the later-described uniform magnetic flux density becomes remarkable.

In the present invention, the magnetic field formed by the magnetic field forming means in the track-shaped erosion region has a component perpendicular to the target (vertical component) at a position where the magnetic flux density is zero (horizontal component). )) And the ratio of the absolute value B _b of the magnetic flux density to the absolute value B _a of the magnetic flux density (B _b /
B _a ) makes the magnetic flux density uniform at 0.9 to 1.1 at all points in the track-shaped erosion region, whereby local erosion of the target can be suppressed.

As an example of a specific means for making the magnetic field uniform, the corner magnet 2 may be a stronger magnet than the linear magnet 1. In this case, the corner magnet 2
Is preferably 10% or more larger than the maximum energy product of the linear magnet 1. Further, by changing the size of the magnet, that is, by making the sectional area of the corner magnet 2 larger than the sectional area of the linear part magnet 1, the magnetic flux density can be made uniform.

As the target 5 in the present invention, there is a target suitable for sputtering in a strong magnetic field as in the present invention. For example, a conductive oxide target such as an ITO (oxide of indium and tin) target or a zinc oxide target doped with Ga or the like can be given.

[0016]

In a magnetron sputtering apparatus, secondary electrons (hereinafter, simply referred to as electrons) emitted from a target move in a direction perpendicular to the magnetic field and the electric field (drift motion) while being trapped by the magnetic field, causing ionization collision. Generates plasma. In the case of the magnetron cathode unit, a magnetic field is formed so that electrons orbit around the target, and a dense plasma is formed even at a low gas pressure.

However, when the magnetic flux density is strong, more drift motion is required to obtain sufficient energy for electrons emitted from the target to cause ionization collision. When the magnetic flux density of the rectangular magnetron cathode unit is increased, the magnetic flux density at the corner portion (curved portion) becomes considerably weaker than the magnetic flux density at the straight portion because of the rectangular shape.

Therefore, since the effect of confining electrons by the magnetic field is small at the corner, the electrons at the corner can easily obtain the energy required for ionization collision, and the electrons cause many ionization collisions near the corner. As a result, a very dense plasma is locally generated near the corner, causing significant erosion and reducing the target use efficiency. According to the present invention, by uniformizing the magnetic flux density in the portion along the erosion, the occurrence of ionization collision can be uniformed, and local erosion of the target near the corner can be suppressed.

[0019]

EXAMPLE The following experiment was conducted using a magnetron cathode unit as shown in FIGS. The size of the unit was 740 mm in length, 140 mm in width, and 40 mm in height. The straight portion peripheral magnet 1a and the straight portion central magnet 1b are samarium-cobalt permanent magnets (maximum energy product is 183 kJ / m ³ ), and the corner portion peripheral magnet 2a
And the corner central magnet 2b are made of a neodymium iron-based permanent magnet (a maximum energy product of 342 kJ /
m ³ ), and the magnetic yoke 3 was made of SUS430. A linear magnet 1 and a corner magnet 2 as magnetic field forming means were provided on a magnetic yoke 3, and a tunnel-shaped magnetic field was formed on a target 5.

FIG. 3 is a diagram showing a magnetic field distribution on a target of the magnetron cathode unit according to the present embodiment.
FIG. 3A shows a magnetic field distribution mainly along the center line (AA line) of FIG. 1 formed by the linear magnet 1, and shows a position where the magnetic flux density of the vertical component of the magnetic field is zero. The absolute value B _a of the magnetic flux density of the horizontal component was 0.097T. FIG. 3B shows a magnetic field distribution along a BB line (a bisector of a short side of a rectangle) of FIG. 1, which is mainly formed by the corner magnet 2, and shows a vertical component of the magnetic field. magnetic flux density at the position of zero, the absolute value B _c of the magnetic flux density of the horizontal component, 0.09
8T, and the ratio (B _c / B _a ) was 1.01.

Further, when a portion other than the portion along the BB line was also examined, the absolute value of the magnetic flux density of the horizontal component at the position where the vertical component of the magnetic field was zero in the track-shaped erosion region where the target was cut was obtained. the ratio of _{B b (B b / B a} )
Was in the range of 0.9 to 1.1 at all points in the erosion area.

Using this magnetron cathode unit, the I.sub.2 I.sub.3 atmosphere is placed in an atmosphere of 5 mTorr Ar gas 100%.
TO (However, based on the total amount of In ₂ O ₃ and SnO ₂
5 kW using a target containing 10 wt% of SnO ₂ )
After the electric power was discharged for 80 hours to perform sputtering, the erosion shape of the target was measured. FIG. 4 is a diagram showing the measured erosion shape of the target. The most eroded point was 5 mm deep, and was indicated by contour lines every 1 mm of erosion depth. It can be seen that they are almost uniformly removed. The target utilization efficiency is 20%
It was a high value.

[Comparative Example] Regarding the corner magnet 2,
The same as the above example except that a samarium cobalt-based permanent magnet similar to the linear magnet 1 was used instead of the neodymium iron-based permanent magnet. FIG. 5 is a diagram showing the measured erosion shape of the target. The most eroded point was 5 mm deep, and was indicated by contour lines every 1 mm of erosion depth. As can be seen from FIG.

FIG. 6 is a diagram showing a magnetic field distribution on a target of the unit of the comparative example. FIG. 6A is a center line (AA line) of FIG. 1 mainly formed by the linear magnet 1.
Shows the magnetic field distribution of the portion along the, in the magnetic flux density at the zero position of the vertical component of the magnetic field, the absolute value B _a magnetic flux density of the horizontal component was 0.097T. FIG. 6B shows the magnetic field distribution mainly along the line BB in FIG. 1 formed by the corner magnet 2, and shows the horizontal component of the magnetic field at the position where the magnetic flux density of the vertical component is zero. Absolute value B of magnetic flux density
_c is 0.073T, and the ratio (B _c / B _a ) is 0.7
It was 8. The target use efficiency was 15%, which was a low value.

[0025]

According to the magnetron cathode unit of the present invention, even when the magnetic field on the target is strong, local significant erosion near the corner can be suppressed, and the amount of the target to be cut by sputtering is substantially reduced within the erosion region. It is possible to increase the target utilization efficiency by making the target uniform.

[Brief description of the drawings]

FIG. 1 is a plan view of an example of a magnetic field forming means in a magnetron cathode unit of the present invention.

FIG. 2 is a schematic cross-sectional view of the magnetron cathode unit of the present invention including a cross section taken along the line AA of the magnetic field forming means of FIG.

3A and 3B are diagrams showing a magnetic field distribution on a target of a unit according to an embodiment of the present invention ((a) is a magnetic field distribution along a line AA in FIG. 1, and (b) is a line B- in FIG. 1). Magnetic field distribution along the line B).

FIG. 4 is a diagram showing an erosion shape of a target in the example of the present invention.

FIG. 5 is a diagram showing an erosion shape of a target in a comparative example.

6A and 6B are diagrams showing a magnetic field distribution on a target of a unit of a comparative example ((a) is a magnetic field distribution along a line AA in FIG. 1, and (b) is a line BB in FIG. 1). Along the magnetic field distribution).

[Explanation of symbols]

 1: Linear part magnet (first part of magnetic field forming means) 1a: Linear part peripheral magnet 1b: Linear part central magnet 2: Corner part magnet (second part of magnetic field generating means) 2a: Corner part peripheral magnet 2b: Corner part center Magnet 3: Magnetic yoke 4: Backing plate 5: Target 6: Substrate

Claims (2)

[Claims] 1. A rectangular magnetron cathode unit used in a magnetron sputtering apparatus, the magnetron cathode unit having a target, further disposed on a back side of the target with respect to a substrate on which a thin film is to be formed, And a rectangular magnetic field forming means for forming a magnetron magnetic field on the substrate-side surface of the target. The magnetic field forming means mainly applies a magnetic field to a linear portion of a track-shaped erosion region where the target is cut by sputtering. And a second part that mainly forms a magnetic field with respect to the curved part of the track-shaped erosion region. The first part of the magnetic field forming means forms two or more long sides of a rectangle. The target at the position where the magnetic flux density of the component perpendicular to the target surface of the magnetic field on the branch line is zero Absolute value B _a magnetic flux density of the horizontal components bets surface is at least 0.02 T, the magnetic field the magnetic field forming means is formed in the track-shaped erosion area, flux density component perpendicular to the target is zero The ratio (B _{b )} between the absolute value B _b of the magnetic flux density of the component horizontal to the target at the position and the absolute value B _a of the magnetic flux density
/ _Ba ) is 0.9 to 1.1 at all points in the track-shaped erosion region. 2. The magnetron cathode unit according to claim 1, wherein the magnetic field forming means is a magnet, and the maximum energy product of the magnet of the second part is larger than the maximum energy product of the magnet of the first part by 10% or more.