JPH0959772A - Magnetron sputtering method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a magnetron sputtering method which is capable of expanding the erosion region of a target without considerably changing the structure and size of a magnetron sputtering device of a conventional type and is capable of prolonging the life of a target material and forming uniform films on a substrate as the film quality, such as resistivity, is improved as well. SOLUTION: A magnet 5 is alternately arranged with N poles and S poles and is made oscillable in a lateral direction, i.e., in a direction perpendicular to the longitudinal direction of the magnet 5. A ground shield 11 and a shielding anode 8 are both held at ground potential together with the base 6b of a chamber 6. The target 10 is stuck to a backing plate 12. Gas shower pipes 7 are arranged on the outside of the shielding anode 8. Auxiliary electrode rods 9 insulated from both of the ground shield 11 and the target 10 are arranged between the shielding anode 9 and the target 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetron sputtering method for forming a coating film on a substrate, and more particularly to a magnetron sputtering method capable of making a film thickness uniform and enhancing target utilization efficiency.

The present invention also relates to a magnetron sputtering method capable of forming an ITO transparent conductive film having a low resistivity.

[0003]

2. Description of the Related Art FIG. 4 is a schematic sectional view showing an example of a conventional planar type magnetron sputtering apparatus. As shown in the figure, the planar magnetron sputtering device is
A gate valve 101, a cathode 103, a substrate heater 104 as main structures in a chamber 100 having an exhaust port.
Is provided. The substrate 102 is attached at a position facing the cathode 103.

The cathode 103 is a backing plate 1
05, 106, target 107, shield anode 1
08, the gas introduction pipe 109. A negative voltage is applied to the target 107 via a backing plate 105 by a sputtering power source having an anode. The magnet 106 is filtered and extended in a direction perpendicular to the paper surface.

In the above-mentioned conventional sputtering apparatus, the shield anode 108 is also usually installed and used together with the target 107. Therefore, the plasma generation region is determined by the total potential between the shield anode 108 and other (for example, the chamber 100, a substrate holder that holds the substrate 102 (not shown), etc.) installed electrodes and the cathode 103.

[0006]

In the prior art shown in FIG. 4, the magnet 1 on the surface of the target 107 is used.
The region between the rows of 06 becomes the erosion area of the target. However, since the magnet 106 is fixedly arranged, this erosion area is considerably narrowed, and there is a problem that the utilization efficiency of the target is low. there were.
Further, since the plasma is generated in a considerably expanded state, the amount of ions reaching the substrate 102 is increased, which causes a problem that the quality of the formed film is deteriorated.

The present invention has been made in order to solve the above-mentioned problems of the conventional technique, and its purpose is to significantly change the structure and size of the conventional magnetron sputtering apparatus. Since the erosion area of the target can be expanded without any improvement and the film quality such as resistivity is improved, the magnetron sputtering method that can extend the life of the target material and perform uniform film formation on the substrate is provided. Is what you are trying to do.

[0008]

According to the magnetron sputtering method of the present invention, a sputtering target is set on the surface of a rectangular parallelepiped cathode capable of confining a magnetic field by a magnet, and a negative potential is applied to the target in a depressurized atmosphere. In the magnetron sputtering method in which the target is sputtered by the generated plasma and the substrate is coated on the surface of the substrate while moving the substrate in a direction perpendicular to the longitudinal direction of the cathode, the magnet of the cathode is sputtered by erosion. The regions are arranged so as to form two closed curves, and are reciprocated in a direction perpendicular to the longitudinal direction of the cathode.

In the present invention, it is preferable that the relationship between the moving speed Vm of the reciprocating motion and the moving speed Vc of the substrate is Vm / Vc ≦ 0.1 3 or more and an odd number of 17 or less, or 19 or more.

In the present invention, an electrically grounded earth shield for stabilizing the plasma formed on the target surface is provided, which has an opening on the target surface, and which has a target surface and an earth shield. It is preferable to provide a rod-shaped or pipe-shaped anode in parallel with the longitudinal direction of the cathode so as to form a predetermined space, and apply a positive voltage to the anode.

In this case, it is preferable to apply a positive voltage of 20 to 40 V to the anode. Further, it is preferable that the reciprocating motion of the magnet is performed within a range in which the position of the magnet does not reach the lower part of the anode.

In the present invention, ITO is used as the target.
Using a sintered body, the oxygen concentration in the atmosphere is 0.1-1.0%
Then, a low resistance ITO film can be formed by coating the ITO film on the substrate.

Further, an ITO target is used as a target, and a plurality of magnetic field generating means of 5 or more, which are swingable in a direction orthogonal to the longitudinal direction of the ITO target, are provided.
A shield anode is provided surrounding the ITO target and having an opening for the ITO vaporized particles to reach the substrate from the target, and an auxiliary electrode is provided between the shield anode and the target for insulation from the shield anode. By applying a positive bias voltage to the auxiliary electrode, a low resistance ITO transparent conductive film can be formed.

In the magnetron sputtering method of the present invention, the number of erosion grooves is reduced from the usual two to four by forming the magnetic field generating means with five magnets.
By swinging this in a direction perpendicular to the longitudinal direction of the target, the target utilization efficiency is dramatically increased. Further, by applying a positive bias voltage to the auxiliary electrode which is insulated from the shield anode and provided between the shield anode and the target, the sputtering voltage is lowered, and the ITO film having a low resistivity is formed by suppressing the abnormal discharge. Can be membrane.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an example of a magnetron sputtering apparatus used in the method of the present invention. As shown in the figure, in this sputtering apparatus, a chamber 6 is provided with a gate valve 1, a cathode 3 and a substrate heater 4 as main components. 2 is a substrate.

FIG. 2 is an enlarged view of the cross section of the cathode portion of this sputtering apparatus. The magnets 5 are extended in a line in the direction perpendicular to the paper surface. In this embodiment, the N poles and the S poles are alternately arranged in opposite directions in the vertical direction, and can swing in the left-right direction in FIG. 2, that is, in the direction perpendicular to the longitudinal direction of the magnet 5. The earth shield 11 and the shield anode 8 are at earth potential together with the bottom surface 6b of the chamber 6. The target 10 is attached to the backing plate 12. The gas shower pipe 7 is arranged outside the shield anode 8.

Further, the shield anode 8 and the target 1
Between 0, the auxiliary electrode rod 9 insulated from both the earth shield 11 and the target 10 is arranged.

The auxiliary electrode rod 9 may have any shape, but as shown in FIG. 11, the auxiliary electrode bar 9 has a hollow inside and a hollow communicating with the outside. It is effective in ensuring a clean surface.

FIG. 3 shows a method of applying a voltage to the cathode portion. A minus voltage −Vc is applied to the target 10 by the sputtering power source 14 via the backing plate 12. A positive voltage + Va is applied to the auxiliary electrode 9 by the auxiliary power supply 13. In addition,
The magnet 5 may be either a permanent magnet or an electromagnet. The shield anode 8 and the earth shield 11 are electrically separated from the backing plate 12 by an electric insulating material 15.

FIG. 5 (a) shows the surface of a target sputtered by the sputtering apparatus for a certain period of time. FIG. 5 (b) is an arrangement pattern diagram of the magnets 5, FIG. 5 (c).
FIG. 6 is a correspondence diagram between the erosion area E and the position of the magnet 5.

FIG. 6 shows a magnet 5 in this apparatus.
While reciprocating in the left and right directions in FIGS. 1 and 2 at a speed Vm, the substrate 2 is moved in the right direction in FIGS.
The thickness difference ratio (the difference between the maximum film thickness d _max and the minimum film thickness d _{min) that} is the film thickness unevenness on the surface of the substrate 2 when the swing stroke of the magnet 5 is set to 50 mm. The film thickness d _{max, that} is, the measured value of (d _max −d _min ) / d _max ) is shown. As shown in FIG. 6, it is apparent that the film thickness unevenness is extremely small (0.1 or less) when Vm / Vc is set to the following value.

(1) Vm / Vc ≦ 0.1
Vm / Vc ≦ 0.05 (2) Vm / Vc = 3,5,7,9,11,13,1
5, 17 (3) Vm / Vc ≧ 19 Note that FIG. 9 is a schematic cross-sectional view showing the film formation state (the degree of film overlap) in the regions ,.

The method of attaching the film at the points is as follows.

When the magnet is moving in the same direction as the substrate, that part is stationary with respect to the substrate. Therefore, assuming that there is no width between the evaporation point and the film formation point immediately above it, the film thickness on that point becomes infinite, so that the film thickness difference / film thickness at that point = ∞ / ∞ → 1. Actually, the evaporation point has a width, so the film thickness is finite, but the film thickness difference is still very large,
It takes a value close to 1.

The method of attaching the film in the region is as follows.

When the magnet swing speed exceeds the substrate transport speed, the magnet overtakes the substrate when moving in the same direction as the substrate. Therefore, the film may be moved in the opposite direction to be formed again on a part of the formed film.

The manner of attaching the film at points, ... Is as follows.

When the magnet is moving in the same direction as the substrate transport direction, the edges of the layers formed are aligned, so that the film thickness is uniform (below), but depending on how the edges overlap, minute unevenness may occur. Can be done.

In the present invention, it is necessary that the magnets 5 have an odd number of rows of 5 or more. In the third row, the film thickness difference ratio becomes extremely large, which is inappropriate.

The reason why the film thickness difference is bad when the magnets are arranged in three rows, that is, in a single erosion, is presumed as follows.

When the magnet is arranged as shown in FIG. 7 (A), electrons move in the direction of the arrow on the target as shown in FIG. 7 (B), and the plasma clings to the space on the surface of the target. Is formed as. At this time, there are two regions where the plasma density is slightly higher at the circled corners. An earth shield is installed on the target,
When the magnet moves in the a direction parallel to the paper surface, the circled portion approaches the earth shield, which causes the film on the right half of the substrate to become thick. On the other hand, when the magnet moves in the b direction, the circle on the left side approaches the earth shield, and the left half film becomes thick. This balances the film thickness in the longitudinal direction of the target, but it is difficult to secure the balance of the film. That is, if the swing width is made large in order to increase the target utilization efficiency, it becomes difficult to achieve balance, and it is difficult to simultaneously realize the uniformity of the film thickness and the improvement of the target utilization efficiency.

On the other hand, in the double erosion in which the magnets are arranged in five or more rows and two closed loop-shaped erosion regions are formed as in the present invention, plasma is generated as shown in FIG. 7 (C). There are four high-density areas, but the plasma in the circled area comes close to the earth shield due to the rocking of the magnet at two of them, and such uniformity of the film thickness in the longitudinal direction of the target. Since one half of the total loss is caused, the difference in film thickness in the transport direction can be reduced while suppressing the occurrence of film thickness unevenness in the target longitudinal direction.

(Experimental Examples 1 to 8) The apparatus shown in FIGS. 1 and 2 (Experiment Nos. 1 to 6) and the apparatus having three magnet rows (Experiment Nos. 7 and 8) were used, and IT was used as a target.
Sputtering using O (In ₂ O ₃ 90%, SnO ₂ 10%) 0.04 Pa, O ₂ 0.5%, Ar 99.
It was carried out under the conditions of 5% and substrate moving speed of 0.5 m / min. Other main experimental conditions are shown in Table 1 together with the experimental results.

[0034]

[Table 1]

FIG. 8 is a sectional view of the target in Experimental Example 2 after 116 hours of sputtering. First
FIG. 3 is a cross-sectional view of the target after the sputtering of Experimental Example 7 (3 magnet arrangement). In these sectional views, the scale in the depth direction is about four times the scale in the target width direction. FIG. 8 (a) is VIII-VIII of FIG. 5 (a).
A line section is shown.

The target use efficiency ε is shown in FIG. 8 (b).
It is defined by the following equation using S ₁ and S ₂ shown in FIG. 8A in which S ₁ and S ₂ are written in the same section.

Ε = S ₂ / (S ₁ + S ₂ ) × 100 (%) That is, the target use efficiency is defined as a percentage obtained by dividing the wear amount of the target by the original amount of the target.

(Experimental Examples 9 to 15) Except that the anode voltage, cathode voltage, input power, and film thickness were as shown in Table 2,
No. Sputtering was performed in the same manner as in 2.

The experimental results are shown in Table 2.

[0040]

[Table 2]

(Experimental example 16) The cathode applied voltage was set to 300.
V, the voltage applied to the anode was 30 V, and the oxygen concentration in the atmosphere was variously changed between 0 and 1.3%. Sputtering was performed in the same manner as in 2, and the specific resistance of the formed ITO thin film was measured. Results are shown in FIG.

(Experimental Example 17) The cathode applied voltage was set to 300.
Sputtering was performed in the same manner as in Experimental Example 16 except that V and the voltage applied to the anode were 0 V, and the specific resistance of the formed ITO thin film was measured. Results are shown in FIG.

From FIG. 12, the oxygen concentration is 0.1 to 1.0.
It can be seen that the specific resistance decreases when the content is set to%.

When the voltage is set to 30 V, the specific resistance is shifted to the side where the oxygen concentration is low as a whole. In addition,
Therefore, there is an advantage that the oxygen consumption amount is also small.

As a result of various experiments, the following was found regarding the dimensions a, b, c and d in FIG.

| (A−b) / (a + b) | <0.5
In particular, | (a−b) / (a + b) | <0.1 is preferable. Outside this range, the effect is reduced and arcing appears.

It is preferable that c ≧ 0. When c <0, arcing increases.

0.5 <[d / (c + d)] and particularly 0.6 <[d / (c + d)] <0.8 are preferable. Outside this range, the arcing increases and the rate (film thickness) decreases.

[0049]

As described above, the magnetron sputtering method of the present invention has a large number of erosion grooves and can swing them in the direction perpendicular to the longitudinal direction of the grooves. Can be expanded. Therefore, the life of the target material can be extended.

In addition, the magnetron sputtering apparatus of the present invention lowers the sputtering voltage by applying a positive bias voltage to the auxiliary electrode which is insulated from the shield anode and is provided between the shield anode and the target, thereby reducing the resistivity. It is possible to form an ITO film having a low resistance.

Further, since discharge during sputtering occurs between this auxiliary electrode and the target, it is possible to suppress abnormal discharge which tends to occur due to an increase in the plasma density in the center of the target due to an increase in the number of erosion grooves. effective.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a magnetron sputtering apparatus according to the present invention.

FIG. 2 is a sectional view showing an example of a cathode peripheral portion according to the present invention.

FIG. 3 is a sectional view showing how a voltage is applied to an auxiliary electrode according to the present invention.

FIG. 4 is a schematic sectional view showing an example of a conventional planar type magnetron sputtering apparatus.

FIG. 5 is a cross-sectional view showing an erosion profile of a target according to the present invention.

FIG. 6 is a correlation diagram of a film thickness difference ratio and Vm / Vc.

FIG. 7 is an explanatory diagram of a generation state of magnetic force lines.

FIG. 8 is a cross-sectional view showing erosion of a target.

FIG. 9 is a film stacking diagram showing a film formation state of a sputtered film.

FIG. 10 is a cross-sectional view of a main part of the embodiment apparatus in which dimensions a, b, c, d are entered.

FIG. 11 is a perspective view showing a preferred example of an auxiliary electrode.

FIG. 12 is a diagram showing the oxygen concentration dependence of the resistivity of the ITO film formed by the magnetron sputtering apparatus according to the present invention.

FIG. 13 is a cross-sectional view showing erosion of a target.

[Explanation of symbols]

 1 Gate Valve 2 Substrate 3 Cathode 4 Substrate Heater 5 Magnet 6 Chamber Wall 7 Gas Shower Pipe 8 Shield Anode 9 Auxiliary Electrode 11 Earth Shield 12 Backing Plate 13 Auxiliary Power Supply 14 Sputtering Power Supply

Claims (9)

[Claims] 1. A sputtering target is installed on the surface of a rectangular parallelepiped cathode capable of confining a magnetic field with a magnet, a negative potential is applied to the target in a depressurized atmosphere, and the target is sputtered by the generated plasma, In the magnetron sputtering method of coating a film on the surface of the substrate while moving the substrate in a direction perpendicular to the longitudinal direction of the cathode, magnets of the cathode are arranged so that the sputtering erosion region forms two closed curves. And a reciprocating motion in a direction perpendicular to the longitudinal direction of the cathode. 2. The relationship between the moving speed Vm of the reciprocating motion and the moving speed Vc of the substrate according to claim 1, wherein Vm / Vc ≦ 0.
1. The magnetron sputtering method characterized in that 3. The magnetron according to claim 1, wherein the relationship between the moving speed Vm of the reciprocating motion and the moving speed Vc of the substrate is such that the ratio Vm / Vc is an odd number of 3 or more and 17 or less. Sputtering method. 4. The magnetron sputtering method according to claim 1, wherein the relationship between the moving speed Vm of the reciprocating motion and the moving speed Vc of the substrate is such that the ratio Vm / Vc is 19 or more. 5. The electrically grounded earth shield for stabilizing the plasma formed on the target surface according to claim 1, comprising an opening on the target surface, and An auxiliary electrode that is provided so as to form a predetermined space with the earth shield and is insulated from the rod-shaped or pipe-shaped earth shield in parallel to the longitudinal direction of the cathode, and applies a positive voltage to the auxiliary electrode The magnetron sputtering method characterized in that 6. The auxiliary electrode according to claim 5,
A magnetron sputtering method characterized in that a positive voltage of -40 V is applied. 7. The magnetron sputtering method according to claim 5, wherein the reciprocating motion of the magnet is performed within a range in which the position of the magnet does not extend below the auxiliary electrode. 8. The ITO film according to claim 1, wherein an ITO sintered body is used as the target, the oxygen concentration in the atmosphere is 0.1 to 1.0%, and the ITO film is applied to the substrate. The magnetron sputtering method characterized in that 9. The ITO target according to claim 1, wherein an ITO target is used as the target, and five or more magnetic field generating means capable of swinging in a direction orthogonal to a longitudinal direction of the ITO target are provided. A shield anode disposed so as to surround the ITO target and having an opening for the ITO vaporized particles to reach the substrate from the target, in a space surrounded by the shield anode and the target by being insulated from the shield anode; A magnetron sputtering method comprising providing an auxiliary electrode and applying a positive bias voltage to the auxiliary electrode to form an ITO transparent conductive film.