JPS61104074A - Sputtering device - Google Patents

Abstract

PURPOSE:To obtain the titled device capable of forming a film at high speed and capable of increasing the availability of a target by providing a magnetic circuit for generating magnetic flux along the moving direction of the microwave which is introduced from an opening provided to the target and a cathode and magnetic flux to cover the target. CONSTITUTION:A voltage is impressed in a vacuum vessel 6 by an electric power source 9 between target 1 placed on a cathode 4 and an anode 7 in a sputtering device. In the device, an opening of a plasma generating chamber 11 is provided at the central part 10 between said target 1 and the cathode 4, microwave from a microwave generating source 16 is introduced from waveguides 12 and 15 connected to the opening to generate plasma 25, and sputtering is carried out. In the device, magnetic devices 17 and 18 are further furnished to generate magnetic flux 22 along the moving direction of the microwave and arcuate magnetic flux 23 to cover the target 1. Consequently, the plasma 25 can be highly densified almost over the whole surface of the target 1, and sputtering is efficiently carried out at high speed over the whole surface of the target 1.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a sputtering apparatus in the process of forming thin films of semiconductor devices, etc., and in particular, to increase the sputtering film forming rate and target life, and to make the thickness of thin films uniform. The present invention relates to a sputtering source suitable for.

[Background of the invention]

In sputtering film formation, the target material placed on the cathode is
This is carried out by colliding ions with energy greater than a predetermined value, and the constituent atoms or particles of the target material emitted by the collision adhere and deposit on the semiconductor substrate to form a thin film i.

As a device for sputtering film formation, the Japanese Patent Publication No. 53-193
This is mentioned in Publication No. 19 and is a reminder. According to this device, a pair of magnetic poles of a magnetic device are provided on the back side of the target material surface of the cathode, and arc-shaped lines of magnetic force are formed by the magnetic device along the cathode surface. The charged particles of the plasma generated by applying a voltage between the positive and negative electrodes are
By maintaining the cyclotron motion using the magnetic lines of force, a higher density of plasma can be generated and a higher film forming rate can be obtained than in a two-pole sputtering device.

In this method, ■ the plasma region becomes ring-shaped;
■High-frequency or @flow power is used to generate plasma and provide energy for ion collisions to the target.Increasing the power supplied for the purpose of increasing the film formation rate increases the ion target energy. If the collision energy is too large, the temperature of the target surface will increase, resulting in destruction of the target due to large temperature stress. or,
In this method, the plasma region becomes ring-shaped and the target is eroded! Since the area also has a similar shape, only a part of the target material contributes to film formation, and the target life was short.
As one method of reducing the collision energy of one ion, as shown in Japanese Patent Application Laid-open No. 75839/1983,
Some use microwaves to generate plasma. In this method, microwaves are applied to a cathode that holds charged particles of plastic by magnetic lines of force, and the energy is absorbed to generate a high-density plasma, while a voltage is applied between positive and negative electrodes. All charged particles in the plasma are accelerated and collided with the target to form a sputter film.

In this method, the number of ions that collide with the target (v) increases due to the high plasma density, so a faster film formation rate can be obtained than with the above-mentioned apparatus. The problem of low contribution to the film remains unsolved.

[Purpose of the invention]

The purpose of the present invention is to generate high-density plasma over almost the entire surface of the target, to make the erosion region of the target almost the entire target surface, and to reduce the temperature stress of the target material without making the ion collision energy extremely large. It is an object of the present invention to provide a sputtering apparatus that enables high-speed film formation in a stable condition, increases the efficiency of target use, and makes the thickness of a thin film uniform during sputtering film formation.

[Summary of the invention]

In the present invention, plasma generation uses microwave number t',
A magnetic device is used to hold plasma at high density and over a large area, and the magnetic device described above is used to make the thickness of a thin film uniform in sputtering film formation.) The plasma holding shape and plasma density can be controlled. This method is used to form a film by sputtering.

That is, in the present invention, microwaves are incident in a direction parallel to or along the static magnetic field of the plasma generation part, and the intensity of the static magnetic field is set to 2-45 GEz under the cyclotron resonance condition. In this case, the magnetic field strength is 875 gauss or more, and by using it to generate a magnetic field to restrain the plasma on the target surface of the magnetic device that generates this mirror magnetic field, the plasma transport distance is minimized and the diffusion of the plasma is reduced. In addition, by configuring this magnetic device with a plurality of magnetic circuits, it is possible to control the intensity distribution, shape, etc. of the magnetic lines of force on the tagelt.

Next, a supplementary explanation will be given regarding the generation and density of plasma.

When generating plasma using microwaves, it is important how effectively the microwaves contribute to plasma generation.
This determines the plasma density.

Electromagnetic waves in plasma without a magnetic field are 1. Expressed as a wave number vector, it is 1, =! However, ω is the incident electromagnetic wave frequency, which is given by the plasma frequency, and when ω is negative, electromagnetic waves cannot propagate into the plasma. In other words, for example, '1.4
In the microwave of 5011z, the plasma density is 7.4
It cannot propagate into plasma exceeding X1 o10/cd. In other words, plasma generated by 2.45 GHz microwave has a plasma density of 7.4 in the absence of a magnetic field.
It can be seen that it does not exceed X101°/cd.

On the other hand, the propagation state of electromagnetic waves in a plasma with a static magnetic field differs depending on the angle between the traveling direction of the electromagnetic waves and the magnetic field. In particular, when electromagnetic waves are introduced into the plasma parallel to the magnetic field, the dispersion formula for right-handed circularly polarized waves is:

However, ・3・Paω. :Electron cyclotron frequency -ωc :
An electromagnetic wave with a frequency given by the ion cyclotron frequency, 0 × ω × ω, propagates in the plasma regardless of the plasma density.

In other words, if a static magnetic field is provided and a microwave is incident parallel to this static magnetic field, the strength of this static magnetic field can be reduced to electron cyclotron resonance (875 GHz at 245 GHz).
G) By doing the above, the right-handed circularly polarized wave propagates in the plasma and supplies microwave power to the plasma, so
The plasma frequency ω2 is ω2>ω9, and the plasma density is 7. axlo”/ctl (1o
t2/, 1 or more).

The plasma generated as described above needs to be restrained by a magnetic device. If this is not done, the plasma will diverge and will not be dense, resulting in large microwave power losses. Furthermore, after the plasma is generated, it must be quickly transported to the vicinity of the target. This is because the plasma density decreases due to diffusion during transportation.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 4.

1 and 2 are cross-sectional views showing the structure of a sputter film forming section of a sputtering apparatus according to a first embodiment. The target 1 and the substrate 2 face each other in a plane, and the target 1 is placed in close contact with a cathode 41C on its back surface with a backing plate 3 in between, and the cathode 4 is placed in a vacuum chamber 6 with an insulator 5 in between. The anode 7 is connected to the anode 7 through the insulator 5 of the cathode 4.
is installed, and the anode 7 is installed in the vacuum chamber 6 via an insulating plate 8. A power source 9 is installed between the positive and negative electrodes.

Here, the center part 10 of the target 1 becomes hollow,
A plasma generation chamber 11 is disposed in this portion, and a waveguide 12 is installed on the outer periphery of the plasma generation chamber 11 via an insulator 13 to the cathode 4. Another waveguide 15 is attached to the waveguide 12 by a flange 14, and a microwave generator 15 is installed at the other end of the waveguide 15. Further, a magnetic device 17 is installed on the outer periphery of the seven flange 14 of the waveguide 15, and another magnetic device 18 is installed on the back surface of the cathode 4.

Here, the magnetic device 18 includes a plurality of magnetic coils 18α,
It is composed of 18b and 18C, and the magnetic field strength of each can be controlled independently.

The plasma generation chamber 11 is made of a material (for example, quartz, alumina porcelain, etc.) that allows microwaves to pass through but maintains a vacuum, and is installed in the vacuum chamber so as to maintain a vacuum.

Further, the substrate 2 is placed on a substrate holder 19, and the substrate holder 19 is installed in a state in which it is electrically insulated by a shaft 20 via an insulator 21 and can hold JE2.

In the above configuration, the magnetic devices 17 and 18 constitute a mirror magnetic field, and the magnetic lines of force are as shown in FIG.
The lines of magnetic force 22 of No. 7 spread out at the center of the magnetic device 18, where the magnetic flux density is small, and become embedded again at the center of the magnetic device 18, and furthermore, the lines of magnetic force 23 on the target 1 emerge from the cavity 1o of the target 1. The magnetic device is configured so that it is approximately parallel to the surface of the target 1 on the target 1 and plunges into the cathode 4 at the end of the target 1. Here, the sputtering film forming chamber 24 is kept in a predetermined vacuum state u (about 10-'' to 10-' Tarr) of atmospheric gas (for example, argon gas, etc.).
Exhaust the air.

When the microwave generation source 16 generates microwaves, the microwaves are guided through the waveguide 15, sent to the waveguide 12, and further passed through the plasma generation chamber 11. On this occasion,
Due to the silent magnetic field created by the magnetic devices 17 and 18, the microwave ionizes the atmospheric gas in the plasma generation chamber 11 and turns it into a plasma state.

Here, by making the center magnetic field strength of the magnetic device 17 larger than the center magnetic field strength of the magnetic device 18, the plasma is sent to the cavity 10 of the target 1 along the lines of magnetic force 22, and further along the lines of magnetic force 23 to the target 1. is transported to the entire surface of the target 1, and a plasma 25 is generated on the surface of the target 1. Here, since the plasma in the plasma generation chamber 11 has a static magnetic field and the lines of magnetic force 22 are along the direction of propagation of the microwave, it is a high-density plasma (plasma density le).

==1011/- or more). Due to the proximity of the plasma generation chamber 11 to the surface of the target laser 810 and the application of electric power to the cathode 4, the charged particles undergo cyclotron motion along the magnetic lines of force 25 and rotate while drifting in the circumferential direction of the target 1. The plasma 25 on one surface also becomes a high-density plasma state.

Applying υ power from the power source 9 between the positive and negative electrodes.

A negative electric field is generated on the surface of the target 1, and ions in the plasma are accelerated and collide with the surface of the target 1. As a result, atoms or particles ejected from the surface of the target 1 adhere and deposit on the surface of the substrate 2 to form a thin film.

Since the plasma 25 on the surface of the target 1 has a high density, the number of ions in the plasma is large, and a low voltage is sufficient to be applied by the power source 9. As a result, the negative electric field on the surface of the target 1 does not become excessively strong, and the plasma 25
Since the erosion area covers the entire surface of the target, the eroded area of the target 1 is also large and the temperature stress applied to the IK remains small.

In addition, since the target is hollow in the center, there is no ova or particles flying from the center as seen in the past, and even if the entire surface of the target becomes an erosion area, the thickness of the thin film deposited on the surface of the substrate 2 is uniform. It is not necessary to make the target diameter extremely large, and the rate at which atoms or particles ejected from the target 1 adhere to and deposit on the substrate 2 is high, and the effectiveness of sputtering film formation is improved.

A plurality of magnetic coils 1f3a, 18 of the magnetic device 18
A.

It is possible to control each 18C independently. Therefore, it is possible to control the strength of the magnetic field parallel to the target 1, which is shunted in the radial direction of the target, and thereby the plasma 2
The radial density distribution of 5 can be controlled. As a result, the higher the plasma density, the greater the number of atoms or particles ejected from the target 1, and the thickness of the film deposited on the substrate 2 in the radial direction can be controlled.

Next, a second embodiment of the present invention will be described (see FIGS. 5 and 4). The configuration of the sputter film forming section of the sputtering apparatus of this embodiment is the same as that of the first embodiment, but the target 1
A backing plate 3' is installed on the outer peripheral surface of the target 1', and a cathode 4- is installed in close contact with the outer peripheral surface of the backing plate 3'. The cathode 4' is installed in a vacuum chamber 6FC via an insulator 5', and an anode 7' is also installed in a vacuum IA6 via an insulating plate 8 on the cathode 4' via the insulator 5'. . Power supply 9 between these positive and negative electrodes
Set up. The central part 10' of the target 1' is hollow as in the first embodiment, and the plasma generation chamber 11 is made of a material that allows microwaves to pass through and maintains a vacuum, and the waveguide 12 is made of an insulator 1f. Another waveguide 15 is attached to the waveguide 12 by a flange 14, and a microwave generation source 16 is installed at the other end of the waveguide 15.

A magnetic device 17 is installed on the outer periphery of the seven flange 14 of the waveguide 12.15, and another magnetic device 18 is installed on the conical outer peripheral surface of the cathode 4', and a plurality of magnetic coils 18α,
18b and 18C, each of which is installed on the cathode 47 in the same way. The substrate 2 is the same as in the first embodiment. Furthermore, the structure of the magnetic devices 17 and 18 is the same as that of the first embodiment, and forms a mirror magnetic field.
Inside, the lines of magnetic force (22') pass through the cavity in the central portion 10' of the target 1', and the lines of magnetic force (23') enter the cathode 4' at the outer periphery of the target 1'.

In the above configuration, plasma 25' is generated by microwave discharge and sputtering is performed as in the first embodiment.

In this embodiment, in addition to the features of the first embodiment, the target 1' has a conical shape, and these surfaces are inclined so as to surround the substrate.

As a result, the height of deposition on the surface of the substrate 2 is increased, and the rate of deposition of the thin film on the substrate is increased even when the same power is supplied and the same target atoms or particles are repelled from the target.

It is known from experimental results that the co-outerg' law holds regarding the flight direction and amount of atoms or particles ejected from the surface of the target 1' (for example, the University of Tokyo Press, Kami Kanehara [ Sputtering phenomenon J, 19134, 3
(published monthly).

〔Effect of the invention〕

According to the present invention, a high-density plasma (plasma density of 5l = 10''/c++ or more) is generated by combining microwaves and a fast field, and this is transported over a short distance to the target 1' and a magnetic field for plasma generation is generated. By applying electric power to the target and the target, charged particles can be confined and almost the entire area on the target surface can be in a high-density plasma state.As a result, the number of ions in the plasma increases, so a large amount of electric power is applied between the positive and negative electrodes. Even if a voltage is applied, the voltage can be suppressed to a low level by increasing the current.
Therefore, the collision energy of ions can be kept low, and sputtering can be performed with less thermal shock to the target. Furthermore, since the eroded area of the target by ions can be increased, the number of atoms or particles ejected from the target increases, which not only speeds up sputtering film formation, but also increases the target eroded area, which greatly reduces the usage height of the target. You can improve.

Furthermore, by adjusting the tilt of the target in consideration of the flight direction and amount of atoms or particles, it is possible to increase the rate at which atoms or particles ejected from the target adhere to the substrate. Furthermore, since microwaves are used to generate plasma and a separate power source is used to generate the energy of ions colliding with the target, the number of ions colliding with the target and their energy can be individually controlled and sputtering conditions can be set to match the target material. This makes it possible to improve production efficiency, material usage efficiency, and power usage efficiency.

[Brief explanation of the drawing]

1 is a sectional view showing the structure of a film forming section of a sputtering apparatus according to a first embodiment of the present invention, FIG. 2 is a sectional view showing magnetic lines of force and plasma in the film forming section of FIG. 1, and FIG. This figure is a sectional view showing the structure of the film forming section of a sputtering apparatus according to the second embodiment of the present invention, and FIG. 4 is a sectional view showing magnetic lines of force and plasma in the film forming section of FIG. 1.1'...Target 2...Substrate 4.4'
...Cathode, 7.7'...Anode 11.
...Plasma generation chamber i4,15...Waveguide 16.
...Microwave source 9...Power supply 17.18...
Magnetic device 6... Vacuum chamber 22, 22', 25.
25'...Magnetic field line 25.2 da...Plasma island 1 Curse 2 Mejima E verbal abuse 4-■

Claims (1)

[Claims] 1. A sputtering apparatus comprising a target made of a sputtering material and facing a deposition surface of a sample substrate, a cathode on which the target is placed, and a power source that applies electric power to the cathode, comprising: A sputtering apparatus comprising: an opening for introducing microwaves into the cathode; a magnetic circuit that generates magnetic lines of force along the direction of propagation of the microwaves; and a magnetic circuit that generates arcuate lines of magnetic force that cover the target. 2. In the sputtering apparatus according to claim 1, the opening for introducing the microwave is installed to face the deposition surface of the sample substrate, and its dimensions are equal to or smaller than the microwave blocking dimension. A sputtering device characterized by: 3. In the sputtering apparatus according to claim 1, the magnetic circuits that generate lines of magnetic force along the direction of propagation of the microwaves are a pair of magnetic circuits, and the magnetic force by the magnetic circuits on the target side is applied to the microwaves. A sputtering device characterized by making the magnetic force weaker than that of the magnetic circuit on the entrance side. 4. The sputtering apparatus according to claim 1, wherein a plurality of magnetic circuits are provided to generate arcuate lines of magnetic force covering the target, and lines of magnetic force are generated individually. 5. The sputtering apparatus according to claim 1, wherein the strength of the magnetic lines of force is set to be equal to or higher than a critical magnetic field strength that satisfies an electron cyclotron resonance condition according to the frequency of the microwave.