JP2000273624A - Magnetron sputtering equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To retain discharge under relatively low gas pressure and to form a film with high controllability by forming the magnetron magnetic field on the surface of a target at the magnet part in a vacuum vessel, blowing off gas for discharge toward the plane of the target, generating discharge and executing sputtering. SOLUTION: A vacuum vessel 16 is connected to a vacuum pump 18 via a gate valve 17, the inside thereof is set with a substrate 15 via a substrate holder 19, oppositely thereto, a target 21 is arranged on a backing plate 23, and the circumference thereof is provided with an earth shield 24. The magnetron magnetic field is formed on the surface of the target 21 by a magnet 22, discharge gas of Ar or the like is fed from nozzles 14, D C or high frequency voltage is applied on the target 21 from a power source 26, discharge is generated, and sputtering is executed by the generated ions. At this time, the center axes of the blow-off of the plural nozzles 14 fitted to a distributor 13 are allowed to place in the plane of the target 21. In this way, gaseous molecular density in the surface of the target 21 is increased, and discharge is made maintainable under low gas pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetron sputtering apparatus for forming a thin film by a magnetron sputtering method.

[0002]

2. Description of the Related Art A magnetron sputtering apparatus is one of thin film forming apparatuses used in the manufacture of electronic components such as semiconductor manufacture, liquid crystal display element manufacture, magnetic heads and magnetic disks.

[0003] A magnetron sputtering apparatus is an apparatus for processing a substrate on which a thin film is to be formed in a vacuum vessel reduced in pressure by a vacuum pump. Immediately before the film is formed on the substrate in the magnetron sputtering apparatus, the pressure inside the vacuum vessel is set to a high vacuum of 1 × 10 ⁻⁴ Pa or less. There is. The reason why such a pressure is selected will be described below.

A magnetron sputtering apparatus is a thin film forming apparatus that scatters, that is, sputters a target material when ions collide with the target and deposits the target material as a thin film on a substrate. These ions are obtained by ionizing an inert gas such as argon. In the magnetron sputtering apparatus, secondary electrons are also emitted from the target when ions collide with the target, and the secondary electrons are accelerated at high speed in the sheath region and jump into the gas.

[0005] Since high-speed electrons stay on the target surface for a long time due to the magnetron magnetic field on the target surface, the probability of collision with gas molecules increases. The fast electrons collide with the gas molecules to ionize the gas molecules and obtain ions.
The discharge is maintained by repeating a cycle in which the ions collide with the target and generate secondary electrons. As described above, in a magnetron sputtering apparatus, electrons can be kept near a target by a magnetic field and discharge can be maintained even at a relatively low gas pressure. However, the gas pressure is generally 0.1 Pa or more.

In forming a thin film, it is necessary to control the properties of the thin film such as crystallinity and stress. This is because the size and properties of the crystal affect the physical properties of the thin film, and the stress has an effect such as deformation of the substrate. The properties of such thin films are complicated, such as the temperature during film formation, the entrainment of atmospheric gas into the film, and the energy of sputtered particles, and have not been completely elucidated.

[0007] In order to control the properties of the thin film, it is actually performed by changing the film forming conditions. Specifically, it is controlled by controlling the substrate temperature, gas pressure during film formation, film formation speed, energy of ions to be sputtered, and the like.

[0008] Of these, the gas pressure during film formation is required to be 0.1 Pa or more because of the necessity of maintaining discharge as described above, and a pressure lower than 0.1 Pa cannot be controlled.

[0009]

It is known that, among film characteristics, film stress, in particular, is easily affected by gas pressure during film formation. Depending on the type of the film, a high stress of 1000 MPa or more may occur. As described above, the gas pressure is a very important parameter as a film forming condition, and the wider the variable range, the easier it is to obtain desired film characteristics.

However, in the magnetron sputtering apparatus, about 0.1 Pa is the limit of the discharge maintenance as described above. Even if a pressure of 0.1 Pa or less is required in view of the pressure dependency of the stress, the discharge maintenance is conventionally performed. And it was impossible to form a film. Therefore, a magnetron sputtering apparatus capable of maintaining discharge even at a lower gas pressure has been desired.

[0011]

The above object can be attained by setting the central axis of the gas introduction nozzle, which is the emission direction of the gas introduction nozzle, as the target surface in the gas introduction mechanism of the magnetron sputtering apparatus.

Since the conductance inside the nozzle is small,
On the upstream side, the gas molecule density is high and the flow is viscous or intermediate. Therefore, the gas immediately after being emitted from the nozzle has directivity. Once gas molecules collide with the inner wall of the vacuum vessel, they turn in random directions. By guiding to the target surface before colliding with the inner wall of the vacuum vessel, the gas molecule density on the target surface can be increased. As a result, the pressure on the substrate surface can be made lower than the conventional gas pressure while maintaining the discharge on the target surface.

[0013]

FIG. 1 is a sectional view of a magnetron sputtering apparatus embodying the present invention.

The vacuum vessel 16 is evacuated by a vacuum pump 18 mounted via a gate valve 17. The substrate 15 is placed on the substrate holder 19. The substrate 15 is heated by the heater 20 on the back.

The target 2 is located at a position facing the substrate 15.
1 is arranged. The target 21 is adhered to the backing plate 23. By cooling the backing plate 23, the target 21 is also cooled. The backing plate 23 also serves as a pressure partition against the atmosphere.

The insulating seal 25 is provided on the backing plate 23.
Is electrically insulated from the vacuum vessel 16 and serves as a vacuum seal for the backing plate 23.

The procedure of film formation will be described below.

First, the substrate 15 is set at a predetermined position, and the temperature is adjusted by the heater 20. Next, an argon gas is introduced into the vacuum chamber 16. Argon gas cylinder 1
From 1, it is guided to the surface of the target 21 via the mass flow controller 12, the distributor 13 and the nozzle 14. The pressure in the vacuum vessel 16 depends on the flow rate of the argon gas and the vacuum pump 1.
8 and the exhaust conductance of the gate valve 17. Next, the target 21 is
Is set to a negative potential with respect to the vacuum vessel 16, discharge plasma is formed on the surface of the target 21.

In this plasma, positively charged argon ions are present and collide with a target having a negative potential.
Due to the collision, the material constituting the target 21 is repelled at the atomic level and deposited on the substrate 15. Also target 2
Secondary electrons are also emitted from 1 by collision of argon ions. Secondary electrons get much kinetic energy from the target and jump out into the argon gas.

However, a tunnel-like magnetic field called a so-called magnetron magnetic field is formed on the surface of the target 21 by the magnet 22. Because of this magnetic field, the secondary electrons stay on the surface of the target 21 for a long time, and thus collide with argon gas molecules with high probability. This collision ionizes the gas and generates argon ions again.

FIG. 2 is a top view of a cross section of the magnetron sputtering apparatus embodying the present invention.
Gas is introduced from around 1 by a nozzle 14.
The pipe 27 distributes gas equally to each nozzle.

[0022]

The argon gas molecular density on the surface of the target 21 can be increased by the nozzle 14. In the example, the discharge could be maintained even when the pressure inside the vacuum vessel 16 was 0.05 Pa. On the other hand, in the conventional magnetron sputtering apparatus shown in FIG.
6 almost uniformly collides with the inside of
At the following pressures, discharge could not be maintained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a cross section of a magnetron sputtering apparatus according to an embodiment of the present invention as viewed from the side.

FIG. 2 is a diagram showing a cross section of a magnetron sputtering apparatus according to an embodiment of the present invention as viewed from above.

FIG. 3 is a view of a cross section of a conventional magnetron sputtering apparatus viewed from above.

[Explanation of symbols]

11, 31 ... gas cylinder, 12, 32 ... mass flow controller, 13 ... distributor, 14 ... nozzle, 15, 35 ...
Substrates, 16, 36: vacuum vessel, 17, 37: gate valve,
18, 38: vacuum pump, 19, 39: substrate holder, 2
0, 40 ... heater, 21, 41 ... target, 22, 4
2 ... magnet, 23, 43 ... backing plate, 2
4,44 ... earth shield, 25,45 ... insulation seal,
26, 46 ... power supply, 27 ... piping.

Claims (1)

[Claims] 1. A vacuum vessel having a substrate disposed therein, a target made of a base material to be formed into a thin film, a magnet section for forming a desired magnetron magnetic field on the surface of the target, and a DC voltage applied to the target. Alternatively, in a magnetron sputtering apparatus having a power supply for generating a discharge on the target surface by applying a high-frequency voltage, and a discharge gas introduction mechanism, the discharge gas introduction mechanism includes:
A magnetron sputtering apparatus having a nozzle shape in the vacuum vessel, wherein a center axis of a blowout of the nozzle is located in the target surface.