JPS63282259A - Sputtering device - Google Patents

Abstract

PURPOSE:To prevent the generation of crevasses and cracks in the deposited film at the stepped part of a substrate by depositing the sputtered particles from a target on the substrate, and simulataneously projecting a particle beam on the substrate in the title counter target-type sputtering device. CONSTITUTION:A couple of counter targets 1, the substrate 4, a particles beam generator 20, and a sputtered particles filter 8 are arranged in a vacuum vessel 15. A permanent magnet 3 is placed on the rear of a target holder 2, and a magnetic field is generated in the direction vertical to the surface of the target 1. The inside of the vessel 15 is firstly evacuated, the flow rate of gaseous Ar is adjusted to provide a specified pressure in the generator 20 and between the targets 1, a high-frequency coil 22 is energized to produce plasma, the ion in the plasma is allowed to collide with the target 1, and the particles sputtered from the targets are deposited on the substrate 4. Meanwhile, the ion beam drawn out from the generator 20 is projected on the substrate 4. By this method, the generation of crevasses and cracks can be prevented even in the film formed on the stepped part on the substrate 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sputtering apparatus, and particularly to a facing target type sputtering apparatus suitable for high-speed film formation.

[Conventional technology]

2. Description of the Related Art In the manufacturing process of semiconductor devices, thin film magnetic heads, etc., film formation using a sputtering apparatus is essential. Many sputtering apparatuses have been developed so far. Among them, pages 1715 to 1716 (JAPAN, J, A
PPL, PHYS, VOL, 16, Nα9 (19
77) pp1715-1716), the substrate is not placed on the discharge electrode, so it has the advantage of being able to form a film at a low temperature and without the substrate coming into contact with the plasma generated by the discharge. be.

Regarding the improvement of this sputtering equipment, please refer to Japanese Patent Application Laid-Open No. 58-15
As described in Japanese Patent No. 1473, a method has been proposed in which a control electrode is provided between a target and a substrate to adjust the kinetic energy of electrons and ions impacting the substrate.

[Problem that the invention seeks to solve]

The conventional facing target type sputtering equipment has many advantages, but with this equipment, it is possible to
For example, depositing an alumina film results in narrow openings called frebus.

The above-mentioned conventional technology does not give consideration to film formation that provides good film properties, particularly mechanical properties, at the stepped portions, and there is a problem in that the film formed at the stepped portions is prone to fraying and cracking.

The present invention has been made in view of the above-mentioned points, and an object thereof is to provide a sputtering apparatus that can form a film without causing fraying or cracking at the stepped portion even if the substrate has a stepped portion. It is in.

[Means for solving problems]

The above object is achieved by depositing sputtered particles scattered from a target on a substrate and simultaneously irradiating the substrate with a particle beam such as an ion beam. That is,
A particle beam generator is provided at a position substantially facing the substrate placed on the side of the discharge space between the pair of targets, and at the same time, a discharge is generated between the pair of targets in order to generate sputtered particles. This is achieved by irradiating the substrate with a particle beam.

[Effect]

A vacuum vessel with a pair of opposed targets, a substrate 9 and a particle beam generator is evacuated and a voltage is applied to the pair of targets while supplying a working gas to the discharge space between the pair of targets. Electrons trapped in the discharge space by a magnetic field applied in a direction perpendicular to the target surface and an electric field formed between the target and the substrate (ground potential) ionize the working gas, generating high-density plasma. . Ions contained in the plasma are accelerated by a sheath near the target and collide with the target, causing
Sputtered particles are scattered from the target. A film is formed by depositing these sputtered particles on a substrate, but at this time, by simultaneously irradiating the same substrate with a particle beam,
Even if there is a step on the substrate, the kinetic energy of the particle beam is applied to the film, which mixes the boundaries of films with different growth directions and promotes the surface diffusion of sputtered particles, resulting in frebus and No cracks will occur.

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments of the drawings.

FIG. 1 shows an embodiment of the sputtering apparatus of the present invention. In the figure, a pair of opposing targets 1, a substrate 4, a substrate holder 5, a particle beam generator 20, and a sputter particle filter 8 are provided in a vacuum vessel 15. The target 1 has a hollow disc shape and is fixed to a target holder 2. However, each target does not necessarily have to be a single hollow disk, and a hollow disk-shaped target may be formed by bonding small targets together. A permanent magnet 3 is attached to the back surface of the target holder 2 so that the upper and lower targets 1 have opposite polarity, and generates a magnetic field in a direction perpendicular to the surface of the target 1. Although not particularly shown, the target holder 2 and permanent magnet 3 are water-cooled. The upper and lower targets 1 are
The matching box 11 is further connected to a high frequency power source 12 via a current introduction terminal ↓0, and high frequency power is supplied thereto. The entire substrate holder to which the substrate 4 is attached is rotatable around the central axis of the vacuum container 15. Each substrate 4 can be tilted with respect to the vertical direction, and when the substrate 4 on which a film has been formed is taken out from the substrate outlet 6, the substrate 4 can be turned over from inward to outward. A shield 13 and a shutter 7 that moves up and down are provided between the target 1 and the substrate 4. The ion beam generator 20 located approximately in the center of the vacuum container includes an insulating tube 21 around which a high-frequency coil 22 is wound, and a plasma holding container 25 attached via an insulating material 24 while maintaining airtightness.
An ion beam extraction electrode 23, which is made of a cylindrical carbon with many holes, is attached thereto. The ion beam extraction electrode 23 is composed of a double cylinder, and a positive DC potential is applied to the inner electrode and a negative DC potential is applied to the outer electrode. The high frequency coil 22 is connected to the high frequency power supply 12 via the matching box 11. Between the target 1 and the ion beam generator 2o, there is a hole 2 with many holes similar to the ion beam extraction electrode 23.
A sputtered particle filter 8 made of a heavy cylinder is attached. The vacuum container 15 also has a gas inlet 9 for introducing the operating gas, and an exhaust port 14 for drawing a vacuum using an exhaust device (not shown).

FIG. 2 is a diagram explaining the operation in this embodiment. First, the vacuum container 15 is evacuated to about I x 10-'Torr. Introduce argon gas from the gas inlet 9,
Ion beam generator 20, 5X10-"~1x10"
"2 Torr, 10-"-10-2 between targets 1
Adjust the argon gas flow rate so that Torr.

Plasma (ionized gas) is generated inside the insulating tube 21 when current is passed through the high-frequency coil 22 while operating an electron supply device (not shown) inside the insulating tube 21 . The generated plasma is diffused into the plasma holding container 25, and a nearly uniform plasma density is obtained. When an appropriate voltage is applied to the ion beam extraction electrode 23, the ion beam 31 is extracted in the direction of the arrow (radially).

The energy of the extracted ions is determined by the potential of the inner electrode of the ion beam extraction electrode 23. In our experiment, when extracting argon ions at 300 electron volts, the ion beam current density was 0.2 mA.
/aJ.

While pulling out the ion beam, aim 1 at the upper and lower targets.
When 3.56 MHz high frequency power is injected, discharge starts. A magnetic field is applied by the permanent magnet 3 in a direction perpendicular to the surface of the target 1, and its strength is approximately 150 Gauss at a location approximately equidistant from the two targets 1. The electrons emitted from the target 1, which is a discharge electrode, move in a circular motion as if wrapped around magnetic lines of force, and are confined in the discharge space by the electric field formed between the target 1 and the substrate 4, so that electrons may be caused by collision with neutral gas. Ionization increases and high-density plasma is generated. A sheath is formed near the target 1, and ions in the plasma are accelerated by the electric field of the sheath and collide with the target 1. Among the sputtered particles 30 scattered from the target 1, those directed toward the substrate 4 are
By opening the shutter 7, it is deposited on the substrate 4.

During this time, the substrate 4 is irradiated with the ion beam 31 extracted from the ion beam generator 20.

When an alumina film is formed using this equipment, the film formation speed is
It is about 4 to 5 μm/hour. In addition, in order to evaluate the film quality at the step portion, step coverage was measured while changing the energy of irradiated ions. FIG. 3 is a diagram showing the relationship between ion energy and step coverage.

The step coverage was defined as the minimum film thickness at the sloped part of the deposited film relative to the film thickness at the flat part. In addition, when frebus or cracks occurred, the step coverage was considered to be zero. As FIG. 3 shows, irradiation with ions above a certain energy significantly improves step coverage. The minimum energy of ions that improves step coverage is about 200 electron volts, although it varies depending on the alumina film formation conditions.

Here, the function of the sputtered particle filter 8 in the embodiment described above will be explained. If the particle filter 8 were not provided, the sputtered particles 3o from the target 1 would adhere to the ion beam extraction electrode 23, which would require frequent cleaning of the ion beam extraction electrode. On the other hand, since the sputtered particle filter 8 can be easily removed, it can be replaced periodically. The sputtered particle filter 8 is composed of two plates in which a large number of holes are formed at positions where the ion beam 31 extracted from each hole of the ion beam extraction electrode 23 advances straight. FIG. 4 is a schematic diagram showing the function of the sputtered particle filter 8. - As an example, from two points on the target 1 it is shown how the sputtered particles 30 pass through the two holes from below the particle filter 8. Most of the sputtered particles 30 adhere to the sputtered particle filter 8 . The remaining sputtered particles 30 adhere to the ion extraction electrode 23, but the density of the sputtered particles 30 decreases as the distance from the target 1 increases, so there is no need to frequently clean the ion extraction electrode 23. Since the ion beam 31 travels horizontally, it can easily pass through the sputtered particle filter 8.

In this example, the substrate holder 5 was rotated around the central axis of the apparatus, and the nonuniformity of the film thickness formed on the 3-inch substrate 4 was ±5% or less. In order to obtain even higher uniformity, it is conceivable to rotate each substrate 4 about its center or to perform a rocking motion.

In addition, the ion beam 31 is applied to the insulating film formed on the substrate 4.
Electrons were supplied from an electron supply device (not shown) in order to prevent charging caused by the irradiation.

According to this example, the ion beam is irradiated at the same time as the sputtered particles from the target are deposited on the substrate. This has the effect of promoting the mixing of particles and the surface diffusion of sputtered particles, resulting in a high-quality film that does not cause fraying or cracking.

In the embodiment shown in FIG. 1, concentric cylinders having a large number of holes and having different diameters were used as the ion beam extraction electrode 23.

FIG. 5(a) shows the ion beam extraction electrode 23 of the embodiment shown in FIG. The problem is that it is quite high. Figure 5 (b
) shows another structure of the ion beam extraction electrode 23.

Regular hexagonal prism-shaped electrodes of different sizes are attached to the body 33, and flat plate electrodes 34 with a large number of holes are attached to the sides of the regular hexagonal prism. Using this structure makes it easy to manufacture the electrode.

In the example shown in Fig. 1, only one type of target was used, but multiple types of small targets made of different materials could be used.
It is also conceivable to configure target 1.

FIG. 6 shows another embodiment of the present invention. While the embodiment of FIG. 1 irradiates the substrate with an ion beam, this embodiment shows a case where a neutral particle beam is irradiated. There are particularly effective cases in which neutral particles are chemically involved in film formation.

Regarding the structure of this embodiment, a vacuum container 15 includes a pair of hollow disk-shaped targets 1 facing each other, permanent magnets 3 for applying a magnetic field to the targets, a substrate 4 and a substrate holder 5, a high frequency coil 22, and an insulator. The ion beam generator 2o consisting of a tube 21 and the ion beam extracting electrode 23 and the sputtered particle filter 8 are the same as in the embodiment shown in FIG.
The difference is that a pair of hollow disk-shaped discharge electrodes 4o are provided inside the matching box 11 and are connected to a high-frequency power source 12 via current introduction terminals 10.

Regarding the operation of this embodiment, the process in which the sputtered particles 30 fly from the target 1 to the substrate 4 and the process in which the ion beam 31 is extracted from the ion beam generator 20 are as follows:
This is exactly the same as the embodiment shown in the figure. What is different is the sputtered particle filter 8. In this embodiment, the sputtered particle filter has the role of not only adhering the sputtered particles 30 but also neutralizing the ion beam passing through the sputtered particle filter 8. That is, when 13.45 MHz high frequency power is applied between the discharge electrodes 40, plasma 41 is generated in the sputter filter 8 by discharge. Since the cross-sectional area of neutralization between ions and plasma is considerably larger than that in gas, the ion beam 31 entering the sputtered particle filter 8 is neutralized and becomes a neutral particle beam 42. In other words, the sputtered particle filter 8 also serves as a neutralization chamber. A neutral particle beam 42 is irradiated onto the substrate 4 on which sputtered particles 30 are being deposited. If ions remain in the neutral particle beam 42, they can be removed using a deflector.

According to this embodiment, as in the embodiment shown in FIG. 1, even if the substrate has a difference, a high-quality film without fraying or cracking can be obtained.

In the previous embodiments, beam ions or neutral particle beams are extracted from the particle beam generator and irradiated onto the substrate, but it is also possible to extract an electron beam and irradiate the substrate. Further, although high frequency discharge is used to generate plasma in the particle generator in the embodiments described above, microwave discharge or direct current low pressure arc discharge may also be used.

〔Effect of the invention〕

According to the sputtering apparatus of the present invention described above, sputtered particles from a target can be deposited on a substrate, and at the same time, the substrate can be irradiated with a particle beam having kinetic energy. It mixes the boundaries of films growing in different directions and promotes the surface diffusion of sputtered particles, so it has the effect of obtaining good film properties without fraying or cracking.

[Brief explanation of the drawing]

1 is a perspective sectional view showing an embodiment of the sputtering apparatus of the present invention, FIG. 2 is a longitudinal sectional view for explaining the operation of the embodiment of FIG. 1, and FIG. 3 is an embodiment of the embodiment of FIG. 1. 4 is an explanatory diagram showing the operation of the sputtered particle filter of the embodiment of FIG. 1, and FIG. 5(a) is the ion beam extraction electrode structure of the embodiment of FIG. 1. FIG. S (b) is a cross-sectional view showing another ion beam extraction electrode structure, and FIG. 6 is a vertical cross-sectional view showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Target, 3...Permanent magnet, 4...Substrate, 8...Sputtered particle filter, 13...Shield, 15.Vacuum container, 2o...Ion beam generator,
30... Sputtered particles, 31... Ion beam, 4
2... Neutral particle beam.

Claims (1)

[Claims] 1. A pair of targets serving as discharge electrodes are arranged in a vacuum container so that their surfaces to be sputtered face each other in parallel across a discharge space, and A film is formed on a substrate that has magnetic means for generating a magnetic field in a direction perpendicular to the surface to be sputtered and is placed on the side of the space between the pair of targets so as to face the space. A sputtering apparatus comprising: a particle beam generator capable of depositing sputtered particles from the target onto a substrate and simultaneously irradiating the substrate with a particle beam continuously or intermittently. 2. The device according to claim 1, further comprising a sputtered particle filter between the target and the particle beam generator that attaches and captures sputtered particles flying toward the particle beam generator. A sputtering device characterized by: 3. The sputtering apparatus according to claim 1, characterized in that an ion beam generator is used as the particle beam generator. 4. A sputtering apparatus according to claim 1, characterized in that an electron beam generator is used as the particle beam generator. 5. A sputtering apparatus according to claim 1, characterized in that a neutral particle beam generator is used as the particle beam generator. 6. A sputtering apparatus according to claim 1, characterized in that the target is a hollow disc-shaped target. 7. A sputtering apparatus according to claim 6, characterized in that a particle generator is provided in a hollow portion of the target. 8. The device according to claim 7, characterized in that the particle beam generator is equipped with electric or magnetic means for scattering particles substantially radially from the particle beam generator. Sputtering equipment. 9. The particle beam generator according to claim 8, wherein at least a part of the particle beam generator has a substantially polygonal prism shape, and a mechanism for extracting the particle beam is provided on a side surface of the particle beam generator of the polygonal prism. A sputtering device characterized in that: 10. In the item described in claim 1 above,
A sputtering apparatus comprising a mechanism capable of rotating a plurality of substrates arranged on the sides of the space between the targets about the central axis of the apparatus. 11. In the item described in claim 1 above,
A sputtering apparatus comprising a mechanism for rotating or oscillating each of the above-mentioned substrates about their central axes. 12. In the item described in claim 1 above,
A sputtering apparatus characterized in that a permanent magnet is used as means for generating a magnetic field perpendicular to the surface of the target to be sputtered. 13. A sputtering apparatus according to claim 12, characterized in that a cylindrical permanent magnet is used as the permanent magnet. 14. In the item described in claim 6 above,
A sputtering apparatus characterized in that the target, which is a hollow disk, is made of a plurality of types of target materials. 15. In the item described in claim 1 above,
A sputtering apparatus characterized in that the particle beam generator has a mechanism for generating plasma using direct current, high frequency, or microwave discharge and extracting ions or electrons as the particle beam. 16. In the thing described in claim 5 above,
The sputtering apparatus is characterized in that the particle beam generator comprises an ion beam generator and a neutralization chamber that neutralizes the ion beam by passing it through plasma. 17. A vacuum container, and 1 arranged in the vacuum container so that the surfaces to be sputtered face each other in parallel across the discharge space.
a pair of targets, a magnetic means for generating a magnetic field in a direction perpendicular to the sputtered surface of the pair of targets, and arranged on the side of the space between the pair of targets so as to face the space. a substrate on which a film is to be formed and a pair of targets on which the substrate is placed, and is installed on the side opposite to the side of the space between the pair of targets on which the substrate is placed and approximately in the center of the apparatus; 1. A sputtering apparatus comprising: a particle beam generator that irradiates a particle beam continuously or intermittently. 18. In the item described in claim 17, a plurality of holes are provided between the target and the particle beam generator to attach and capture sputtered particles flying toward the particle beam generator. A sputtering apparatus characterized in that a sputtered particle filter formed of a heavy cylinder is installed, and a pair of discharge electrodes are provided inside the sputtered particle filter. 19. The sputtering apparatus according to claim 18, wherein the pair of discharge electrodes are connected to a matching box and a high frequency power source via current introduction terminals.